Hung’s Difficult and Failed Airway Management [3rd Edition] 9781259640551

Table of contents :
Hung's Management of the Difficult and Failed Airway, 3rd Edition......Page 1
Half Title......Page 2
NOTICE......Page 3
Title Page......Page 4
Copyright......Page 5
ASSOCIATE EDITORS......Page 6
DEDICATION......Page 7
CONTENTS......Page 8
CONTRIBUTORS......Page 14
FOREWORD......Page 20
PREFACE......Page 22
ACKNOWLEDGMENTS......Page 24
SECTION 1 PRINCIPLES OF AIRWAY MANAGEMENT......Page 26
Chapter 1 Evaluation of the Airway......Page 27
Chapter 2 The Al gorithm s......Page 42
Chapter 3 Pre paration for Awa ke Intubation......Page 64
Chapter 4 P harmacology of Drug s U sed in Airway Manage ment......Page 111
Chapter 5 As piration : Ris ks an d Prevention......Page 132
Chapter 6 Human Factors an d Airway Manage ment......Page 153
SECTION 2 AIRWAY TECHNIQUES......Page 160
Chapter 7 Context-Sen sitive Airway Manage ment......Page 161
Chapter 8 Bag -Mas k-Ventilation......Page 168
Chapter 9 Direct Laryn goscopy......Page 180
Chapter 10 F lexib le Bron choscopic Intubation......Page 197
Chapter 11 Rig id Fiberoptic an d VideoLaryn goscopes......Page 223
Chapter 12 Nonvisua l Intubation Techn iques......Page 247
Chapter 13 Extraglottic Devices for Ventilation an d Oxygenation......Page 263
Chapter 14 Cricothyrotomy......Page 284
Chapter 15 Tracheotomy......Page 295
SECTION 3 PRE-HOSPITAL AIRWAY MANAGEMENT......Page 302
Chapter 16 What I s Unique About Airway Manage ment in the Pre Hos pita l Settin g ?......Page 303
Chapter 17 Airway Manage ment of a Patient with Traumatic Brain Injury (TB I )......Page 312
Chapter 18 Airway Management of an Unconscious Patient Who I s Trapped In side the Vehicle Following a Motor Vehicle Collision......Page 325
Chapter 19 Airway Manage ment of a Race Car Driver with a Ful l Face Helmet Fol lowin g a Crash......Page 330
Chapter 20 Airway Management of a Morbid ly Obese Patient Suffering from a Cardiac Arrest......Page 336
Chapter 21 Airway Manage ment with B lunt Anterior Nec k Trauma......Page 345
SECTION 4 AIRWAY MANAGEMENT IN THE EMERGENCY ROOM......Page 350
Chapter 22 Airway Manage ment in the Emergen cy De part ment......Page 351
Chapter 23 Patient with Dead ly Asth ma Requires Intubation......Page 356
Chapter 24 Trachea l Intubation in an Un cooperative Patient With a Nec k Injury......Page 362
Chapter 25 Airway Manage ment for the Burn Patient......Page 366
Chapter 26 Airway Manage ment in a Patient with An gioede ma......Page 370
Chapter 27 Airway Manage ment for Penetratin g Facia l Trauma......Page 375
Chapter 28 Airway Manage ment in a Patient with a Dee p Nec k Infection......Page 380
SECTION 5 AIRWAY MANAGEMENT IN THE INTENSIVE CARE UNIT (ICU)......Page 388
Chapter 29 Unique Airway I ssues in the Inten sive Care Unit......Page 389
Chapter 30 Manage ment of Extubation of a Patient Fol lowin g a Prolon ged Period of Mechanical Ventilation......Page 395
Chapter 31 Airway Manage ment of a Patient in a Ha lo-Jac ket with Acute O bstruction of a Reinforced Trachea l Tube......Page 402
Chapter 32 Manage ment of a Patient Ad mitted to I C U with E bola Virus an d I m pen d in g Res piratory Failure......Page 408
Chapter 33 Performin g an E lective Percutaneous Dilationa l Tracheotomy in a Patient on Mechanical Ventilation......Page 415
Chapter 34 Manage ment of a Patient with a Res piratory Arrest in the Intermediate Care Unit......Page 425
SECTION 6 AIRWAY MANAGEMENT IN THE OPERATING ROOM......Page 432
Chapter 35 Airway Manage ment of an Un cooperative Down Syn drome Patient with an Upper Bleed......Page 433
Chapter 36 Airway Manage ment of a Patient with a H istory of Ora l an d Cervica l Radiation Thera py......Page 438
Chapter 37 Airway Manage ment in Penetratin g Nec k Injury......Page 449
Chapter 38 Airway Manage ment of a Patient in Prone Position......Page 465
Chapter 39 Lun g Se paration in the Patient with a Difficult Airway......Page 475
Chapter 40 Airway Manage ment of a Patient with Superior Vena Cava O bstruction Syn drome......Page 482
Chapter 41 Airway Manage ment in a Patient with As piration of Gastric Contents Followin g I n duction of Anesthesia......Page 488
Chapter 42 Airway Manage ment of a Patient with H istory of Difficult Airway Who Refuses to Have Awa ke Trachea l Intubation......Page 494
Chapter 43 Manage ment of a Patient with OSA for Tota l Thyroidectomy......Page 506
Chapter 44 Airway Manage ment of a Patient with a Difficult Airway Requirin g Microlaryn goscopy, Tracheoscopy, an d P haryn goe......Page 517
SECTION 7 AIRWAY MANAGEMENT IN THE PEDIATRIC POPULATION......Page 532
Chapter 45 Unique Airway I ssues in the Pediatric Population......Page 533
Chapter 46 Manage ment of a 1 2-Year-O i d Child with a Foreign Body in the Bron chus......Page 549
Chapter 47 Manage ment of a C h ild with a H istory of Difficult Intubation an d Post-Ton sil lectomy B leed......Page 555
Chapter 48 Airway Manage ment of a 6-Year-O i d with Pierre Robin Syn drome for Bilatera l I n guinal Hernia Re pair......Page 560
Chapter 49 Cannot Intubate an d Cannot Oxygenate in an Infant After I n duction of Anesthesia......Page 572
Chapter 50 A Neonate with a Difficult Airway an d As piration Ris k......Page 580
SECTION 8 AIRWAY MANAGEMENT IN OBSTETRICS......Page 586
Chapter 51 What I s Unique About the O bstetrical Airway?......Page 587
Chapter 52 Airway Manage ment of the O bstetrical Patient with an Anticipated Difficult Airway......Page 599
Chapter 53 Unanticipated Difficult Airway in an O bstetrica l Patient Requirin g an Emergen cy Cesarean Section......Page 604
Chapter 54 Airway Manage ment of the Pregnant Trauma Victim......Page 610
Chapter 55 Ap pen d icitis in Pregnan cy......Page 614
SECTION 9 AIRWAY MANAGEMENT IN UNIQUE ENVIRONMENT......Page 620
Chapter 56 Unique C h a l len ges of Ectopic Airway Manage ment......Page 621
Chapter 57 Airway Manage ment of the Patient wit h a Nec k He matoma......Page 626
Chapter 58 Airway Manage ment Un der Com bat Con dition s......Page 637
Chapter 59 Airway Manage ment in Austere En vi ron ments......Page 644
Chapter 60 Res piratory Manage ment in the Magnetic Resonan ce I magin g Suite......Page 653
Chapter 61 Post-O bstructive Pu......Page 661
SECTION 10 PRACTICAL CONSIDERATIONS IN AIRWAY MANAGEMENT......Page 670
Chapter 62 Difficult Airway Carts......Page 671
Chapter 63 Documentation of Difficult an d Failed Airway Manage ment......Page 681
Chapter 64 Teachin g and Simulation for Airway Manage ment......Page 687
INDEX......Page 706

Citation preview

Hung's

DIFFICULT AND FAILED AIRWAY MANAGEMENT

NOT IC E

Medicine is an ever-changing science. As new research and clinical experience broaden our knowl­ edge, changes in treatment and drug therapy are required. The authors and the publisher of this work have checked with sources believed to be reliable in their efforts to provide information that is complete and generally in accord with the standards accepted at the time of publication. However, in view of the possibility of human error or changes in medical sciences, neither the authors nor the publisher nor any other party who has been involved in the preparation or publication of this work warrants that the information contained herein is in every respect accurate or complete, and they disclaim all responsibility for any errors or omissions or for the results obtained from use of the information contained in this work. Readers are encouraged to confirm the information contained herein with other sources. For example and in particular, readers are advised to check the product information sheet included in the package of each drug they plan to administer to be certain that the information contained in this work is accurate and that changes have not been made in the recom­ mended dose or in the contraindications for administration. This recommendation is of particular importance in connection with new or infrequently used drugs.

THIRD EDITION

Hung's

DIFFICULT AND FAILED AIRWAY MANAGEMENT ORLA N DO R. HU N G, B S c ( PHARMACY), M D, FRC P (C) Professor, Departments of Anesthesia, Surgery, and Pharmacology Director of Research Department of Anesthesia, Pain Management and Perioperative Medicine Dalhousie University Queen Elizabeth II Health Sciences Centre Department of Anesthesia Halifax, Nova Scotia, Canada

MICHA EL F. MURPHY, M D, FRC P (C) Professor Emeritus, Department of Anesthesiology and Pain Medicine University of Alberta Walter C Mackenzie Health Sciences Centre Edmonton, Alberta, Canada

New York Chicago San Francisco Athens London Madrid Mexico City Milan New Delhi Singapore Sydney Toronto

Copyright© 2018 by McGraw-Hill Education. All rights reserved. Except as permitted under the United States Copyright Act of 1976, no part of this publication may be reproduced or distributed in any form or by any means, or stored in a database or retrieval system, without the prior written permission of the publisher. ISBN: 978-1-25-964055-1 MHID:

1-25-964055-8

The material in this eBook also appears in the print version of this title: ISBN: 978-1-25-964054-4, MHID: 1-25-964054-X. eBook conversion by codeMantra Version 1.0 All trademarks are trademarks of their respective owners. Rather than put a trademark symbol after every occur­ rence of a trademarked name, we use names in an editorial fashion only, and to the benefit of the trademark owner, with no intention of infringement of the trademark. Where such designations appear in this book, they have been printed with initial caps. McGraw-Hill Education eBooks are available at special quantity discounts to use as premiums and sales promo­ tions or for use in corporate training programs. To contact a representative, please visit the Contact Us page at www.mhprofessional.com. TERMS OF USE This is a copyrighted work and McGraw-Hill Education and its licensors reserve all rights in and to the work. Use of this work is subject to these terms. Except as permitted under the Copyright Act of 1976 and the right to store and retrieve one copy of the work, you may not decompile, disassemble, reverse engineer, reproduce, modify, create derivative works based upon, transmit, distribute, disseminate, sell, publish or sublicense the work or any part of it without McGraw-Hill Education's prior consent. You may use the work for your own noncommercial and personal use; any other use of the work is strictly prohibited. Your right to use the work may be terminated if you fail to comply with these terms. THE WORK IS PROVIDED "AS IS." McGRAW-HILL EDUCATION AND ITS LICENSORS MAKE NO GUARANTEES OR WARRANTIES AS TO THE ACCURACY, ADEQUACY OR COMPLETENESS OF OR RESULTS TO BE OBTAINED FROM USING THE WORK, INCLUDING ANY INFORMATION THAT CAN BE ACCESSED THROUGH THE WORK VIA HY PERLINK OR OTHERWISE, AND

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CLAIM ANY WARRANTY, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO IMPLIED WAR­ RANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. McGraw-Hill Education and its licensors do not warrant or guarantee that the functions contained in the work will meet your requirements or that its operation will be uninterrupted or error free. Neither McGraw-Hill Education nor its licensors shall be liable to you or anyone else for any inaccuracy, error or omission, regardless of cause, in the work or for any damages resulting therefrom. McGraw-Hill Education has no responsibility for the content of any information ac­ cessed through the work. Under no circumstances shall McGraw-Hill Education and/or its licensors be liable for any indirect, incidental, special, punitive, consequential or similar damages that result from the use of or inability to use the work, even if any of them has been advised of the possibility of such damages. This limitation of liabil­ ity shall apply to any claim or cause whatsoever whether such claim or cause arises in contract, tort or otherwise.

ASSOCIATE EDITORS Thomas J . Coonan, M D, F RC P (C)

J. Ada m Law, M D, F RC P (C)

Professor, Departments of Anesthesia and Surgery Dalhousie University Queen Elizabeth II Health Sciences Centre Department of Anesthesia Halifax, Nova Scotia, Canada

Professor, Departments of Anesthesia and Surgery Associate Head Department of Anesthesia, Pain Management and Perioperative Medicine Faculty of Medicine, Dalhousie University Queen Elizabeth II Health Sciences Centre Halifax, Nova Scotia, Canada

N a ra s i m h a n Jagan nathan, M D

Associate Chairman, Academic Affairs Director, Pediatric Anesthesia Research Ann & Robert H. Lurie Children's Hospital of Chicago Associate Professor of Anesthesiology Northwestern University Feinberg School of Medicine Chicago, Illinois George Kovacs, M D, FRCP(C)

Professor, Emergency Medicine Dalhousie University Attending Emergency Physician Nova Scotia Health Authority Queen Elizabeth II Health Sciences Centre Halifax, Nova Scotia, Canada

la n R. Morris, B Eng, M D, F RC P(C), DABA, FAC E P

Professor, Department of Anesthesia Dalhousie University Queen Elizabeth II Health Sciences Centre Department of Anesthesia Halifax, Nova Scotia, Canada Ron a l d D. Stewa rt, OC, O N S, E C N S (hon), BA, BSc, M D, FACEP, DSc (hon)

Professor Emeritus Departments of Anesthesia and Emergency Medicine Faculty of Medicine, Dalhousie University Queen Elizabeth II Health Sciences Centre Victoria General Hospital Site Halifax, Nova Scotia, Canada

DEDICATION We would like to thank our families for their understanding and support of our aca­ demic and clinical work by dedicating this edition to: Jeanette, Christopher, David, and Ana Hung and to Debbi, Amanda, Ryan, and Teddy Murphy. We also dedicate this edition to the tireless efforts of all who teach airway management. We are grateful for their commitment to the prevention of death and disability related to airway man­ agement failure.

CON TEN TS Contributors .................................................................................... xiii Foreword ........................................................................................xix Preface

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Acknowledgments ............................................................................. xxiii

PRINCIPLES OF AIRWAY MANAGEMENT 1. Evaluation of the Airway ....

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4. Pharmacology of Drugs Used

Michael F Murphy and

in Airway Management

Johannes M. Huitink

Jonathan G. Bailey, Ronald B. George,

2. The Algorithms

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and Orlando R. Hung

5. Aspiration: Risks and Prevention .....

Michael F Murphy, Edward T. Crosby, and J. Adam Law

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Saul Pytka and Edward Crosby

3. Preparation for Awake Intubation ....

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6. Human Factors and Airway Management .... .

/an R. Morris

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..... .128 .

Peter G. Brindley

AIRWAY TECHNIQUES 7. Context-Sensitive Airway Management

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10. Flexible Bronchoscopic Intubation ... .

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Orlando R. Hung and Michael F Murphy

8. Bag- Mask-Ventilation .. .... .

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George Kovacs, Michael F Murphy, and

Video-Laryngoscopes

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Richard M. Cooper and J. Adam Law

12. Nonvisual Intubation Techniques ....

Richard M. Levitan and George Kovacs

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11. Rigid Fiberoptic and ....

Nicholas Sowers

9. Direct Laryngoscopy

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Chris C. Christodoulou, Orlando R. Hung, and Jinbin Zhang

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viii

Contents

1 3. Extraglottic Devices for Ventilation and Oxygenation .......................238 Liem Ho, Thomas J. Coonan, and Orlando R. Hung

14. Cricothyrotomy.........................259 Gordon 0. Launcelott, Liane B. Johnson,

David T Wong, and Orlando R. Hung

15. Tracheotomy ...........................270 Timothy F. E. Brown and Liane B. Johnson

PRE-HOSPITAL AIRWAY MANAGEMENT 16. What Is Unique About Airway

19. Airway Management of a Race

Management in the Pre-Hospital

Car Driver with a Full-Face Helmet

Setting? ................................278

Following a Crash.......................305

Mark Vu, David Petrie, Michael F. Murphy,

Mark P Vu, Angelina Guzzo, and

and Erik N. Vu

Orlando R. Hung

17. Airway Management of a Patient with

20. Airway Management of a Morbidly

Traumatic Brain Injury (T B I) .............287

Obese Patient Suffering from

J. Adam Law, Edward T Crosby, and Andy Jagoda

a Cardiac Arrest.........................311

18. Airway Management of an Unconscious Patient Who Is Trapped

Saul Pytka and Danae Krahn

21. Airway Management with Blunt

Inside the Vehicle Following a Motor

Anterior Neck Trauma...................320

Vehicle Collision ........................300

David A. Caro

Arnim Vlatten and Matthias Helm

AIRWAY MANAGEMENT IN THE EMERGENCY ROOM 22. Airway Management in the

26. Airway Management in a Patient

Emergency Department ................326

with Angioedema ......................3 45

John C. Sakles and Michael F. Murphy

Genevieve MacKinnon, Michael F. Murphy,

23. Patient with Deadly Asthma Requires Intubation ..............................3 31 Kerryann B. Broderick and Jennifer W Zhan

24. Tracheal Intubation in an Uncooperative Patient With a Neck Injury...............3 37 Kerryann B. Broderick

25. Airway Management for the Burn Patient ............................3 41 Laeben Lester and Darren Braude

and David Petrie

27. Airway Management for Penetrating Facial Trauma...........................350 David A. Caro and Aaron E. Bair

28. Airway Management in a Patient with a Deep Neck Infection .............355 Kirk J. MacQuarrie

Contents

AIRWAY MANAGEMENT IN THE INTENSIVE CARE UNIT (ICU) 29. Unique Airway Issues in the

32. Management of a Patient Admitted to

Intensive Care Unit .....................364

ICU with Ebola Virus and Impending

Shawn D. Hicks, J. Adam Law, and

Respiratory Failure ......................38 3

Michael F. Murphy

30. Management of Extubation of a Patient

Louise Ellard and David T Wong

3 3. Performing an Elective Percutaneous

Following a Prolonged Period of

Dilational Tracheotomy in a Patient

Mechanical Ventilation..................370

on Mechanical Ventilation ..............390

Richard M. Cooper

Angelina Guzzo, Liane B. Johnson,

31. Airway Management of a Patient in a Halo-Jacket with Acute Obstruction

and Orlando R. Hung

3 4. Management of a Patient with

of a Reinforced Tracheal Tube...........377

a Respiratory Arrest in the

Dietrich Henzler

Intermediate Care Unit..................400 Peter G. Brindley

AIRWAY MANAGEMENT IN THE OPERATING ROOM 35. Airway Management of an

41. Airway Management in a Patient with

Uncooperative Down Syndrome

Aspiration of Gastric Contents

Patient with an Upper Gl Bleed..........408

Following Induction of Anesthesia ......46 3

Michael F. Murphy

Kathryn Sparrow and Orlando R . Hung

36. Airway Management of a Patient

42. Airway Management of a Patient

with a History of Oral and Cervical

with History of Difficult Airway

Radiation Therapy ......................413

Who Refuses to Have Awake

/an R. Morris

Tracheal Intubation .....................469

37. Airway Management in Penetrating Neck Injury .............................424 /an R. Morris

38. Airway Management of a Patient in Prone Position .......................4 40 Dennis Drapeau and Orlando R. Hung

39. Lung Separation in the Patient with a Difficult Airway ..................450 ian R. Morris

40. Airway Management of a Patient with Superior Vena Cava Obstruction Syndrome ..............................457 Mathieu Asselin and Gordon 0. Launcelott

Dmitry Portnoy and Carin A. Hagberg

4 3. Management of a Patient with OSA for Total Thyroidectomy ................481 Jinbin Zhang, Frances Chung, and Orlando R. Hung

4 4. Airway Management of a Patient with a Difficult Airway Requiring Microlaryngoscopy, Tracheoscopy, and Pharyngoesophageal Dilation ......492 Jeanette Scott, David Vokes, and L V Duggan

ix

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Contents

AIRWAY MANAGEMENT IN THE PEDIATRIC POPULATION 45. Unique Airway Issues in the

48. Airway Management of a 6-Year-Oid

Pediatric Population ....................508

with Pierre Robin Syndrome for

Narasimhan Jagannathan, Andrea Huang,

Bilateral Inguinal Hernia Repair ..........5 35

Anthony Longhini, and John Hajduk

Ban C.H. Tsui

46. Management of a 12-Year-Oid

49. Cannot Intubate and Cannot

Child with a Foreign Body in

Oxygenate in an Infant After

the Bronchus ...........................524

Induction of Anesthesia.................5 47

Liane B. Johnson

Paul A. Baker and Cedric Ernest Sottas

47. Management of a Child with

50. A Neonate with a Difficult Airway

a History of Difficult Intubation

and Aspiration Risk .....................555

and Post-Tonsillectomy Bleed ...........5 30

Andrea Huang, Sebastian Bienia, John Hajduk

Arnim Vlatten and Matthias Helm

and Narasimhan Jagannathan

AIRWAY MANAGEMENT IN OBSTETRICS 51. What Is Unique About the Obstetrical

5 4. Airway Management of

Airway?.................................562

the Pregnant Trauma

Dolores M. McKeen and Jo Davies

Victim ..................................585

52. Airway Management of the Obstetrical Patient with an Anticipated Difficult

Holly A. Muir

55. Appendicitis in

Airway..................................57 4

Pregnancy ..............................589

Jo Davies and Brian K. Ross

A/lana Munro, Ronald B. George and

5 3. Unanticipated Difficult Airway in an Obstetrical Patient Requiring an Emergency Cesarean Section ...........579 Holly A. Muir

Narendra Vakharia

Contents

AIRWAY MANAGEMENT IN UNIQUE ENVIRONMENT 56. Unique Challenges of Ectopic

59. Airway Management in Austere

Airway Management....................596

Environments ..........................619

Michael F Murphy

Kelly McQueen, Alison B. Froese, Thomas J. Coonan and Jinbin Zhang

57. Airway Management of the Patient

60. Respiratory Management in the

with a Neck Hematoma .................601

Magnetic Resonance Imaging Suite .....628

J. Adam Law and Kitt Turney

Richard D. Roda and Andrew D. Milne

58. Airway Management Under Combat

61. Post-Obstructive Pulmonary

Conditions .............................612

Edema ( P O P E) ..........................636

Matthias Helm and Arnim Vlatten

Matthew G . Simms and J . Adam Law

PRACTICAL CONSIDERATIONS IN AIRWAY MANAGEMENT 6 4. Teaching and Simulation for

62. Difficult Airway Carts....................646

Airway Management....................662

Saul Pytka and Michael F Murphy

Brian Ross, Jo Davies, Sara Kim, and

6 3. Documentation of Difficult and Failed

Michael F Murphy

Airway Management....................656 Lorraine J. Foley, Michael F Murphy and Orlando R. Hung

Answers Index

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CON TRIBUTORS Mathieu Asselin, MD, FRCP(C)

Kerryann B. Broderick, BSN, MD

Department of Anesthesia University of Laval Universitaire de Quebec, Pavillon H6pital Enfant-Jesus Quebec, Quebec, Canada

Associate Professor, Department of Emergency Medicine Denver Health Medical Center University of Colorado, School of Medicine Denver, Colorado

Chapter 40

Chapters 23, 24

Jonathan G. Bailey, MD, MSc

Timothy F.E. Brown, MD, FRCSC

Department of Anesthesia, Pain Management and Perioperative Medicine Dalhousie University Queen Elizabeth II Health Sciences Centre Halifax, Nova Scotia, Canada

Department of Otolaryngology Dalhousie University Queen Elizabeth II Health Sciences Centre Victoria General Site Halifax, Nova Scotia, Canada

Chapter 4

Chapter I5

Aaron E. Bair, MD, MS

David A. Caro, MD

Assistant Professor, Emergency Medicine U.C. Davis Medical Center Sacramento, California

Associate Residency Director Assistant Professor Department of Emergency Medicine University of Florida Health Science Center-Jacksonville Jacksonville, Florida

Chapter 27 Paul A. Baker, MBChB, MD, FANZCA

Clinical Senior Lecturer Department of Anesthesiology University of Auckland, New Zealand Consultant Anaesthetist Starship Children's Hospital Auckland, New Zealand

Chapter 49 Sebastian Bienia, MD

Department of Pediatric Anesthesia Ann & Robert H. Lurie Children's Hospital of Chicago Fellow in Pediatric Anesthesiology Northwestern University Feinberg School of Medicine Chicago, Illinois

Chapter 50 Darren Braude, MD, EMT-P, FACEP

EMS Section Chief/Fellowship Director Professor of Emergency Medicine University of New Mexico Corrales, New Mexica

Chapter 25 Peter G. Brindley, MD, FRCP(C), FRCP, Edin

Adj unct Professor, Department of Anesthesiology and Pain Medicine University of Alberta Hospital Walter C Mackenzie Health Sciences Center Edmonton, Alberta, Canada

Chapters 6, 34

Chapters 2I, 27 Chris C. Christodoulou, MBChB, Cum Laude DA (UK), FRCP(C)

Assistant Professor in Anesthesia Department of Anesthesia and Perioperative Medicine University of Manitoba I.H. Asper Clinical Research Institute Winnipeg, Manitoba, Canada

Chapter I2 Frances Chung, MBBS, FRCP(C)

Professor, Department of Anesthesiology University of Toronto Toronto Western Hospital Toronto, Ontario, Canada

Chapter 43 Thomas J. Coonan, MD, FRCP(C)

Professor, Departments of Anesthesia and Surgery Dalhousie University Queen Elizabeth II Health Sciences Centre Department of Anesthesia Halifax, Nova Scotia, Canada

Chapters I3, 59 Richard M. Cooper, BSc, MSc MD, FRCP(C)

Professor, Department of Anesthesia University of Toronto Department of Anesthesia and Pain Management Toronto General Hospital Toronto, Ontario, Canada

Chapters II, 30 xiii

xiv

Contri b utors Edward T. Crosby, MD, FRCP(C)

Angelina Guzzo, MD, PhD, FRCP(C)

Professor, Department of Anesthesiology University of Ottawa Ottawa Hospital-General Campus Ottawa, Ontario, Canada

Assistant Professor, McGill University Health Centre Department of Anesthesia Montreal General Hospital Montreal, Quebec, Canada

Chapters 2, 5, 11

Chapters 19, 33

Jo Davies, MBBS, FRCA

Carin A. Hagberg, MD

Associate Professor, Department of Anesthesiology University of Washington Seattle, Washington Chapters 51, 52, 64

Joseph C. Gabel Professor and Chair Department of Anesthesiology The University of Texas Medical School at Houston Medical Director of Perioperative Services Memorial Hermann Hospital Houston, Texas

Dennis Drapeau, BSc, MD, FRCP(C)

Staff Anesthesiologist/Assistant Professor Department of Anesthesia Queen Elizabeth II Health Sciences Centre Dalhousie University Halifax, Nova Scotia, Canada

Chapter 38 Laura Duggan, MD, FRCP(C)

Chapter 42 John Hajduk

Clinical Research Coordinator Department of Pediatric Anesthesia Ann & Robert H. Lurie Children's Hospital of Chicago Chicago, Illinois

Chapters 45, 50

Anesthesiology and Pediatrics Assistant Professor Department of Anesthesiology, Pharmacology and Therapeutics University of British Columbia Royal Columbian Hospital New Westminster, British Columbia, Canada

Chief Emergency Medicine Department of Anaesthesiology, Intensive Care Medicine, Emergency Medicine and Pain Therapy Armed Forces Hospital Ulm, Germany

Chapter 44

Chapters 18, 47, 58

Louise Ellard, MBBS, FANZCA, AdvPTEeXAM

Dietrich Henzler, MD, PhD, FRCP(C)

Staff Anaesthetist Department of Anaesthesia Austin Health Victoria, Australia

Professor of Anesthesiology Ruhr University Bochum, Germany Dalhousie University, Halifax, Nova Scotia, Canada Department of Anesthesia, Surgical Critical Care, Emergency and Pain Medicine Klinikum Herford Schwarzenmoorstr, Herford, Germany

Chapter 32 Lorraine J. Foley, MD

Clinical Assistant Professor of Anesthesia Tufts School of Medicine, Boston, Massachusetts Winchester Anesthesia Associates Winchester Hospital Department of Anesthesia Winchester, Massachusetts

Chapter 63 Alison B. Froese, MD, BSc Med, FRCP(C)

Professor Emerita, Queen's University Departments of Anesthesiology, Pediatrics, and Physiology Kingston, Ontario, Canada

Chapter 59 Ronald B. George, MD, FRCP(C)

Assistant Professor, Women's & Obstetric Anesthesia Department of Anesthesia, Pain Management and Perioperative Medicine Dalhousie University IWK Health Centre Halifax, Nova Scotia, Canada

Chapters 4, 55

Prof. Dr. med. Matthias Helm

Chapter 31 Shawn D. Hicks, MD, MSc, FRCP(C)

Assistant Professor, Department of Anesthesiology University of Ottawa The Ottawa Hospital, Civic Campus Ottawa, Ontario, Canada

Chapter 29 Liem Ho, MD

Department of Anesthesia Dalhousie University Queen Elizabeth II Health Sciences Centre Halifax, Nova Scotia, Canada

Chapter 13 Andrea Huang, MD

Department of Pediatric Anesthesia Ann & Robert H. Lurie Children's Hospital of Chicago Instructor in Anesthesiology Northwestern University Feinberg School of Medicine Chicago, Illinois

Chapters 45, 50

Contri b utors Johannes M. Huitink, MD, PhD

Danae Krahn, BHSc (Hons), MD

Assistant Professor Anesthesiology Department of Anesthesiology VU University Medical Center Amsterdam Founder Airway Management Academy Amsterdam, The Netherlands

Chief Resident Anesthesiology Residency Training Program Cumming School of Medicine University of Calgary Calgary, Alberta, Canada

Chapter 1

Chapter 20

Orlando R. Hung, BSc (Pharmacy), MD, FRCP(C)

Gordon 0. Launcelott, MD, FRCP(C) Department of Anesthesia Dalhousie University Queen Elizabeth II Health Sciences Centre Halifax, Nova Scotia, Canada

Professor, Departments of Anesthesia, Surgery, and Pharmacology Director of Research, Department of Anesthesia, Pain Management and Perioperative Medicine Dalhousie University Queen Elizabeth II Health Sciences Centre Department of Anesthesia Halifax, Nova Scotia, Canada

Chapters 4, 7, 12, 13, 14, 19, 33, 38, 41, 43, 63 Narasimhan Jagannathan, MD

Associate Chairman, Academic Affairs Director, Pediatric Anesthesia Research Ann & Robert H. Lurie Children's Hospital of Chicago Associate Professor of Anesthesiology Northwestern University Feinberg School of Medicine Chicago, Illinois

Chapters 45, 50 Andy Jagoda, MD, FACEP

Professor and Chair Department of Emergency Medicine Mount Sinai School of Medicine New York, New York

Chapter 11 Liane B. Johnson, MDCM, FRCSC, FACS

Department of Otolaryngology Dalhousie University Department of Pediatric Otolaryngology IWK Health Centre Halifax, Nova Scotia, Canada

Chapters 14, 15, 33, 46 Sara Kim, PhD

Associate Professor, Department of Anesthesiology and Biolnformatics University of Washington Seattle, Washington Chapter 64 George Kovacs, MD, MD, FRCP(C)

Professor Emergency Medicine Dalhousie University Attending Emergency Physician Nova Scotia Health Authority Queen Elizabeth II Health Sciences Centre Halifax, Nova Scotia, Canada

Chapters 8, 9

Chapters 14, 40 J. Adam Law, MD, FRCP(C)

Professor, Departments of Anesthesia and Surgery Associate Head Department of Anesthesia, Pain Management and Perioperative Medicine Faculty of Medicine, Dalhousie University Queen Elizabeth II Health Science Centre Halifax, Nova Scotia, Canada

Chapters 2, 11, 17, 29, 57, 61 Laeben Lester, MD

Assistant Professor Co-Director, Johns Hopkins Airway Program The Johns Hopkins University School of Medicine Department of Anesthesiology and Critical Care Medicine Division of Cardiothoracic Anesthesia Affiliate Department of Emergency Medicine Baltimore, Maryland

Chapter 25 Richard M. Levitan, MD

Associate Professor, Emergency Medicine Thomas Jefferson University Department of Emergency Medicine Philadelphia, Pennsylvania

Chapter 9 Anthony Longhini, MD

Department of Anesthesiology Northwestern University Feinberg School of Medicine Chicago, Illinois

Chapter 45 Genevieve MacKinnon, MD, FRCP(C)

Assistant Professor Department of Pain Management and Perioperative Medicine Dalhousie University Attending Physician Anesthesiology Nova Scotia Health Authority Queen Elizabeth II Health Sciences Centre Halifax, Nova Scotia, Canada

Chapter 26

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xvi

Contri buto rs Kirk J. MacQuarrie, MD, FRCP(C)

Michael F. Murphy MD, FRCP(C)

Departments of Anesthesia, Surgery and Emergency Medicine Dalhousie University Queen Elizabeth II Health Sciences Centre Victoria General Hospital Halifax, Nova Scotia, Canada

Professor Emeritus, Department of Anesthesiology and Pain Medicine University of Alberta Walter C Mackenzie Health Sciences Centre Edmonton, Alberta, Canada Chapters 1, 2, 7, 8, 16, 22, 26, 29, 35, 56, 62, 63, 64

Chapter 28 Dolores M. McKeen, MD, MSc, FRCP(C)

David Petrie, MD, FRCP(C)

Professor Department of Anesthesia, Pain Management and Perioperative Medicine Dalhousie University IWK Health Centre Halifax, Nova Scotia, Canada

Associate Professor of Emergency Medicine Dalhousie University Attending Physician Emergency Medicine Nova Scotia Health Authority Queen Elizabeth II Health Sciences Centre Halifax, Nova Scotia, Canada

Chapter 51

Chapter 16

Kelly McQueen, MD, MPH

Dmitry Portnoy, MD

Professor, Department of Anesthesiology Director, Vanderbilt Anesthesia Global Health & Development Director, Vanderbilt Global Anesthesia Fellowship Affiliate Faculty, Vanderbilt Institute for Global Health Vanderbilt University Medical Center Nashville, Tennessee

Associate Professor Department of Anesthesiology and Perioperative Care Staff Anesthesiologist UC Irvine Medical Center Orange, California

Chapter 59

Chapter 42 Saul Pytka, MD, FRCP(C)

Assistant Professor, Department of Anesthesia Dalhousie University Queen Elizabeth II Health Sciences Centre Halifax, Nova Scotia, Canada

Associate Professor Department of Anesthesiology University of Calgary Attending Anesthesiologist Rockyview Hospital Calgary, Alberta, Canada

Chapter 60

Chapters 5, 20, 62

Andrew D. Milne, BEng, MSc, MD, FRCP(C)

Jan R. Morris, BEng, MD, FRCP(C), DABA, FACEP

Richard D. Roda, BEng, MASc, MD

Professor, Department of Anesthesia Dalhousie University Queen Elizabeth II Health Sciences Centre Department of Anesthesia Halifax, Nova Scotia, Canada

Department of Anesthesia, Pain Management and Perioperative Medicine Faculty of Medicine, Dalhousie University Queen Elizabeth II Health Sciences Centre Halifax, Nova Scotia, Canada

Chapters 3, 10, 36, 37, 39

Chapter 60

Holly A. Muir, MD, FRCP(C)

Brian K. Ross, PhD, MD

Chair and Professor Department of Anesthesiology, Keck School of Medicine, University of Southern California Los Angeles, California

Chapters 53, 54

Professor, Department of Anesthesiology and Pain Medicine Executive Director Institute for Surgical and Interventional Simulation University of Washington Seattle, Washington Chapters 52, 64

Allana Munro, MD, FRCP(C)

John C. Sakles, MD, FACEP

Women's & Obstetric Anesthesia Department of Anesthesiology, Dalhousie University IWK Health Centre Halifax, Nova Scotia, Canada

Professor, Department of Emergency Medicine University of Arizona College of Medicine Tucson, Arizona

Chapter 55

Chapter 22

Contri b utors Jeanette Scott, MBChB, FANZCA

Kitt Turney, MD

Anesthesiologist Department of Anaesthesia and Pain Medicine Middlemore Hospital Department of Cardiac and ORL Anaesthesia Auckland City Hospital Auckland, New Zealand

Resident Anesthesiologist, Department of Anesthesia, Pain Management and Perioperative Medicine Queen Elizabeth II Health Sciences Centre Halifax, Nova Scotia, Canada

Chapter 44 Matthew G. Simms, MSc, MD, FRCP(C)

Staff Anesthesiologist Department of Anesthesia, Faculty of Medicine Dalhousie University Queen Elizabeth II Health Sciences Centre Halifax, Nova Scotia, Canada

Chapter 61 Cedric Ernest Sottas, MD

Anaesthesia Fellow Department of Pediatric Anaesthesia Starship Children's Hospital Auckland, New Zealand

Chapter 49 Nicholas Sowers, MD

Resident, Emergency Medicine Dalhousie University Halifax Infirmary Halifax, Nova Scotia, Canada

Chapter 8 Kathryn Sparrow, BSc, MD, FRCP(C)

Department of Anesthesia Memorial University of Newfoundland Faculty of Medicine St. John's, Newfoundland and Labrador, Canada

Chapter 41 Ronald D. Stewart, OC, ONS, ECNS (hon), BA, BSc., MD, FACEP, DSc (hon)

Professor Emeritus Departments of Anesthesia and Emergency Medicine Faculty of Medicine, Dalhousie University Queen Elizabeth II Health Sciences Centre Victoria General Hospital Site Halifax, Nova Scotia, Canada

Chapter 57 Narendra Vakharia, MD, FRCP(C)

Associate Professor Dalhousie University Halifax, Nova Scotia, Canada

Chapter 55 Arnim Vlatten, MD

Associate Professor Departments of Anesthesia, Pediatric Anesthesia, and Pediatric Critical Care Dalhousie University Queen Elizabeth II Health Sciences Centre Halifax, Nova Scotia, Canada

Chapters 18, 47, 58 David Vokes, MBChB, FRACS

Laryngologist, Head and Neck Surgeon Department of Otorhinolaryngology Auckland City Hospital Auckland, New Zealand

Chapter 44 Erik N. Vu, CCP, MD, FRCP(C), DAvMed

Assistant Professor, Faculty of Medicine, University of British Columbia Departments of Emergency and Critical Care Medicine British Columbia Emergency Health Services Vancouver, British Columbia, Canada

Chapter 16 Mark P. Vu, MD, FRCP(C)

Assistant Professor Department of Anesthesiology, Pharmacology and Therapeutics University of British Columbia Department of Anesthesiology Vancouver Island Health Authority Victoria, British Columbia, Canada

Chapters 16, 19

Ban C. H. Tsui, Dip Eng, BSc(Math), BSc(Pharm),

David T. Wong, MD, FRCP(C)

MSc(Pharm), MD, FRCP(C), PG Dip Echo

Associate Professor Department of Anesthesia Toronto Western Hospital University of Toronto Toronto, Ontario, Canada

Professor of Anesthesiology Department of Anesthesiology, Preoperative and Pain Medicine Stanford University School of Medicine Stanford, California

Chapter 48

Chapters 14, 32

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Contri butors Jennifer W. Zhan, MD

Jinbin Zhang, MBBS, MMED (Anaesthesiology)

Resident in Emergency Medicine Denver Health Medical Center Denver, Colorado

Consultant, Tan Tock Seng Hospital Clinical Lecturer, Yong Loo Lin School of Medicine National University of Singapore Tan Tock Seng Hospital Singapore

Chapter 23

Chapters 12, 43, 59

FOREWORD Although the practice of anesthesia professionals and others who do airway management is full of unexpected challenges, perhaps nothing strikes more fear in our hearts than a patient with a difficult airway. Unlike other events, which may be limited to certain narrow sub-specialties, challenging airway management occurs across nearly all domains of patient care, all patient ages, and many sites of care such as perioperative, emergency department, ward settings, as well as in unusual sites such as pre-hospital or combat casualty care. Hence, books such as this are vital as contextual compilations of up-to-date infor­ mation on approaches and techniques for the myriad needs of patients for oxygenation and ventilation. Most simply put, the most fundamental goal of airway management is to accomplish what for most patients is routine, but for some is so elusive, which is-as one of my supervising attending and later faculty colleague (Mervyn Maze) put it years ago, to "get some green gas in the right hole [U.S . oxygen color code is green] ." This spirit is exemplified in the modern evolution from the notion of "can't intubate, can't ventilate" to "can't intubate, can't oxygen­ ate" emphasizing that oxygenation comes first with ventilation as important, but still secondary. As noted in the Preface, the third edition of this book con­ tains some important new information and new chapters. I am particularly pleased by the addition of a chapter on human factors and airway management. Over the last few decades we have collectively recognized that all the clinical knowledge or technical dexterity in the world can come to no avail with­ out appropriate design and use of equipment, systems, pro­ cesses, and teamwork. Another key tenet of human factors is the importance of cognitive scientist Don Norman's concept of putting "knowledge in the world" rather than just relying on "knowledge in the head." The creation of a variety of standard protocols for airway management, and their representation in various graphical cognitive aids, is now a well-accepted and critical aspect of modern airway management preparation and execution. Thus, the chapter on the algorithms that describes and compares the many different protocols, mnemonics, and graphics is particularly useful. No one protocol will suit all cli­ nicians and all sites so knowing their individual strengths and weaknesses is important.

A particular strength of this book is the numerous descrip­ tions of airway management alternatives and their pros and cons in a wide variety of specific clinical situations. This is based on the concept-described in its own chapter-of context­ sensitive airway management; this ties in very strongly with human factors and algorithms because every situation is indeed different. The approach of high-reliability organizations is to standardize where possible, but to remain flexible and resilient as circumstances demand. Even for readers who do not usually work in some of the settings described, the well-articulated syn­ thesis of the processes of airway assessment, evaluation of the overall situation, and choice of options will help everyone to hone their decision-making skills whatever their usual setting. In fact, these case discussions are a simple form of "simula­ tion" by storytelling-as clinicians hear or read of a colleague's tough case, they simulate in their own heads what they would think or do in a similar situation. Such case studies thus natu­ rally dovetail with the chapter on the use of simulation to teach, practice, and hone skills of airway management-with simula­ tion techniques ranging from simple procedural task trainers to full-blown interprofessional mannequin-based simulations. This book has already stood the test of time, but the third edition offers a fully modern view of the complexities and nuances of this life-threatening and life-saving arena of clini­ cal care. The authors, contributors, and I share the hope that through the knowledge, skills, attitudes, and behaviors con­ veyed by this book the rightful fear of the difficult airway will be surmounted by mastery and expertise, leading to the preser­ vation or rescue of uncounted hearts, brains, and lives. David M. Gaba, MD Associate Dean for Immersive & Simulation-based Learning Professor of Anesthesiology, Perioperative & Pain Medicine Stanford School of Medicine Staff Physician and Founder & Co-Director, Patient Simulation Center VA Palo Alto Health Care System Palo Alto, California

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PREFACE Since the last edition of our textbook, strategies and guidelines in managing the difficult and failed airway from the American Society of Anesthesiologists, the Canadian Airway Focus Group, the Difficult Airway Society in the United Kingdom, and other organizations have been updated and revised using the currently available evidence. These revised recommenda­ tions for the management of the difficult and failed airway are reflected in all chapters of this edition of the textbook includ­ ing the new chapters. For example, two chapters (Chapters 6 and 34) were added to this edition to address "human factors" as they relate to the stresses and strains of difficult and failed airway management. The Difficult Airway Society guidelines specifically acknowledge the importance of human factors in crisis resource management. Interpreted in context, the appli­ cation of the four basic methods of oxygenation (bag-mask­ ventilation, use of extraglottic devices, tracheal intubation, and front of neck access) remains the most logical approach for managing a failed airway. Furthermore, the National Audit Project 4 (NAP4) and other studies have consistently identified difficulties associated with needle (Seldinger technique) crico­ thyrotomy such that it has become clear that when faced with a "cannot intubate, cannot oxygenate" (CICO) situation, surgical (open) cricothyrotomies are much more successful than needle or Seldinger cricothyrotomies. Many chapters of this edition

emphasized the importance of early front of neck access using open cricothyrotomy in the adult population. This edition is divided into ten sections: the first section consists of the foundational information in airway manage­ ment; the second section reviews airway devices and techniques; the third to the ninth sections discuss airway management in different clinical settings, including prehospital care, in the Emergency Department, the Intensive Care Unit, the operat­ ing room, the Post Anesthetic Care Unit, as well as other parts of the hospital; and the last section highlights practical issues in airway management. A number of new chapters and clinical cases have been added to this new edition. As indicated above, two chapters have been added to discuss human factors in air­ way management. To avoid confusion related to "front of neck" access, a tracheotomy chapter has been added to this edition. In addition, chapters discussing the management of patients with the aspiration of gastric contents, obstructive sleep apnea, tracheal stenosis requiring jet-ventilation, and airway manage­ ment under combat conditions have been added to this edition. Videos depicting all airway management techniques are available at http://DifficultAirwayVideos.com. Bag mask ventilation, topical anesthesia of the upper airway, and open cricothyrotomy videos have been added to this edition.

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ACKNOWLEDGMEN TS We would like to thank all the contributing authors for making this book possible. In addition, we would like to thank all the associate editors (with rwo additional associate editors) for their tireless efforts to ensure that the information in this book is clear and accurate. We wish to thank Sara Whynot for her editorial

assistance, Christopher Hung and David Hung for the production of the images and videos. We also like to thank all of the McGraw­ Hill editorial and production staff for rheir continuing support. Orlando Hung, MD, FRCP(C) Michael F. Murphy, MD, FRCP(C)

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2

CHAPTER 1

Evaluation of the Airway Michael F. Murphy and Johannes M. Huitink

INTRODUCTION.................................. 2 INCIDENCE OF DIFFICULT AND FAILED AIRWAY.. STANDARD OF CARE.

3

.................... 4

DEVELOPMENT OF DIRECT LARYNGOSCOPIC INTUBATION .

5

DEFINITIONS OF DIFFICULT AND FAILED AIRWAYS .. PREDICTION OF DIFFICULT AND FAILED AIRWAY ...... 9 SUMMARY ....... SELF-EVALUATION QUESTIONS.

INTRODUCTION ''Airway management" may be defined as the application of ther­ apeutic interventions that are intended to effect gas exchange in patients who are unable to do it for themselves. Gas exchange is fundamental to this definition.1 A number of devices and techniques are commonly employed in health care settings to achieve this goal. These include the use of bag-mask-ventilation (BMV), extraglottic devices (EGOs), oral or nasal endotracheal intubation (ETI), and invasive or surgical airway techniques. The failure to adequately manage the airway has been identified as a major factor leading to poor outcomes in anesthesia, critical care, emergency medicine, hospital medicine, and emergency medical services (EMS).2·3 Adverse respiratory events constituted the largest single cause of injury in the ASA Closed Claims Project.4 The 4th National Audit Project (NAP4) conducted in the United Kingdom over a 1-year period of time identified major airway management

complications in the operating oom (OR), critical care units, and emergency dep� nts leading to death, brain damage, emergency surgical airway, 30 kg·m - 2) , snoring and sleep apnea, age ( > 56 years), and Mallampati of Grade III or IV were risk factors for difficult ventilation and, in addition, noted that a history of radiation therapy to the neck and severely limited jaw protrusion predicted difficult BMV (see Chapter 8 for a detailed discussion) . Han5 and KheterpaJ3 proposed DMV scales for the purposes of clarity and commu­ nication (see Tables 2- 1 and 2-2) _5.3 DMV in patients under general anesthesia is likely to occur in 2% to 5% of patients and impossible mask-ventilation on the order of one event per thousand anesthetics. 2·3•6 In the emergency situation, other factors may become rele­ vant when considering whether difficulty with mask-ventilation is more likely to be encountered. Trauma to the face with resul­ tant edema, bleeding or debris in the airway, and the need to maintain in-line C-spine immobilization when required may increase the degree of difficulty with mask-ventilation. In addi­ tion, the use of cricoid pressure, often perceived to be necessary in emergency intubations, is recognized to increase the like­ lihood of DMV Petito and RusseW evaluated the impact of

TA BLE 2-1 . C l a ssification of Diffic u lt Bag-Mask-Venti l ation Accord i n g to H a n

Classification

Description/Defi n ition

N o. of Selections

% of Cases

G ra d e 0 G ra d e 1 G ra d e 2 G ra d e 3 G ra d e 4 Co m m e nts Tota l

Ve ntilation by m a s k not atte m pted Ve ntilation by m a s k Ve ntilation by m a s k with o ra l a i rway or oth e r a dj uva nt Difficult mask-ventilation (inadeq uate, u n sta ble, or req u i ri n g two practitioners) U na b l e to m a s k ve nti l ate

449 1 01 0 366 22 1 6 1 854

24.2 54.4 20.0 1 .2 0.05 0.3

Reprod u ced with perm ission fro m Han R, Tre m per KK, Kheterpa l S, et a l . G ra d i n g sca l e fo r mask ve nti lati o n . Anesthesiology. 2004; 1 0 1 ( 1 ) :267.

TA BLE 2-2. C l a ssification of Diffic u lt Bag-Mask-Venti l ation Accord i n g to Kheterpal

Grade

Descri ption

N (%)

1 3 3 4

Ve nti l ated by m a s k Ve nti l ated b y m a s k with o ra l a i rway/a dj uva nt w i t h o r w i t h o u t m u sc l e re l axa nt Diffi c u l t venti lation (inadeq uate, u n sta ble, or req u i ri n g two providers) with or without m u scle re laxa nt U na b l e to m a s k ve nti l ate with o r without m u sc l e re l axa nt Tota l cases

37,857 1 3,966 1 ,1 41 77 53,04 1

(7 1 .3) (26.3) (2.2) (0. 1 5)

Reprod u ced with perm ission fro m Kheterpa l S, M a rt i n L, S h a n ks AM, Tre m p e r KK. Pred iction a n d outcomes of i m poss i b l e m a s k ve nti latio n : a review o f 5 0,000 a n esthetics. Anesthesiology. 2009; 1 1 0 (4):89 1 -897.

The A l g orith m s

cricoid pressure on lung ventilation during BMV Fifty patients were randomized to either with or without cricoid pressure applied during a 3-minute period of standardized mask-ventila­ tion. Patients who had cricoid pressure applied were considered more difficult to ventilate (36% vs. 1 2%), and these patients tended to have more air in the stomach than those patients considered easy to ventilate without applied cricoid pressure. Most of the studies dealing with assessment of the airway in anticipation of tracheal intubation using a laryngoscope have limited applicability to currently available alternative devices (e.g., rigid endoscopic devices, intubating EGDs, and video-laryngoscopes) . S - J O Modification of Mallampati's original schema1 1 as well as alternate strategies to assess the airway (see section "Difficult DL Intubation: LEMON" in Chapter I ) have been proposed. These have ranged from using simple anatomical descriptors, ranking and summating anatomical scoring systems, and using logistic regression to create predic­ tive scales to derive performance indices. These strategies share some common characteristics: they have high sensitivity but low specificity and low positive predictive value with respect to predicting failure. For example, Shiga et al. 1 2 employing a meta-analysis to assess combined Mallampati and temperoman­ dibular joint displacement scores found a positive association with difficult intubation of only 9.9%. Additionally, many of the tests have only moderate inter-observer reliability. 13' 14 Such limitations may help to explain why these tests often fail to pre­ dict difficult tracheal intubation, and why perhaps some practi­ tioners question the ability of preanesthetic airway assessments to accurately and with certainty predict or rule out difficulty. 15 A number of new schemes and techniques used to predict potential airway difficulty have been described; their accuracy and widespread applicability are not yet determined. However, it is likely that they will have a low positive predictive value, similar to current strategies, because of the low incidence of airway diffi­ culty.15' 16 Furthermore, we know that even with careful evaluation, difficulty will not be predicted in many instances. 16·17 Therefore, strategies to manage the unanticipated difficult airway should be preformulated and practiced to minimize adverse outcomes result­ ing from the inevitable occurrence of false-negative predictions.

AI RWAY EMERG E N C I ES • How Is Airway Management in an

Emergency Setting Different?

Airway management in an emergency setting may be compli­ cated by a multitude of factors. Trauma to the face and neck may distort anatomical features or obscure them with blood and debris. Additionally, blood in the airway may absorb a signifi­ cant amount of the light cast by airway devices making recog­ nition of anatomic features more difficult. The requirement for in-line stabilization in patients with spinal injury or perceived to be at-risk for a spinal injury may make DL more difficult.18 Unprepared patients are often associated with a full stomach and are at a higher risk of regurgitation and aspiration of gastric contents. The controversy regarding cricoid pressure has been debated and a rational statement based on the current state of evidence published by the Canadian Airway Focus Group (CAFG) , echoing an editorial by Ovassapian in 2009 . 1 9•20 These

statements take into account that the evidence supporting the use of cricoid pressure is observational only. There is evi­ dence that the maneuver imposes an element of obstruction to the passive regurgitation of gastric contents2 1 and anecdotal evidence that it has prevented aspiration. 22 • 23 On the other hand it has been shown to be difficult to teach and perform, 24 may not protect against aspiration in all patients at risk, 2 5-27 and hinders BMV, EGD insertion and ventilation, and tracheal intubation. 2 8-30 Even a recently published Cochrane Review is unable to resolve the controversy as to whether cricoid pressure should or should not be abandoned in high-risk patients.31 The position of the CAFG is as follows: ''As cricoid pressure is likely to have potential benefits, its continued use seems pru­ dent during rapid sequence intubation in the patient at high risk of aspiration (strong recommendation for, level of evidence C) . However, if difficulty is encountered with face-mask-ventilation or tracheal intubation, or if EGD insertion is needed, progres­ sive or complete release of cricoid pressure is justified." 2 0 The removal of cricoid pressure may improve the view obtained at laryngoscopy and seems unlikely to make the view worse. Harris et al.32 reported the experience of 402 pre-hospital emer­ gency anesthetics and noted that, in settings where the appli­ cation of cricoid pressure was associated with poor laryngeal view, removal of the pressure resulted in improved view in 50% of patients. In the remainder, there was no improvement in view and other measures (BURP or laryngeal manipulation) were employed in an attempt to improve the view and did so in about rwo-thirds. In no patient was the removal of cricoid pressure associated with a worse view. Emergency situations and hemodynamically unstable patients may contraindicate the use of drugs to facilitate laryngoscopy, resulting in intubating conditions which may be less than ideal. Finally, a chaotic emergency environment may distract the prac­ titioner, making it more difficult to manage the airway.

D I F F I C U LT A N D FAI LED AI RWAY • What Does Experience Tel l Us About

Rescuing the Difficult Airway?

Evidence has emerged that having automatic default-to strategies improves the success of rescue airway interventions and reduces the occurrence of adverse outcomes.33 Conversely, there are also data demonstrating that persisting with failing techniques rather than defaulting to rescue strategies results in higher rates of morbidity and mortality.34·35 Rose and Cohen1 reported that difficult laryngoscopy in anesthesia practice was most often managed with persistent attempts at DL, and the use of alter­ native approaches to tracheal intubation was uncommon. In these patients, there was a higher incidence of desaturation, esophageal intubation, dental damage, and unexpected ICU admissions. Similarly, Mort,36 in reviewing the airway man­ agement of 2833 critically ill patients outside of the operating room, noted that the most common strategy implemented for managing difficult intubations was, again, repeated DL. There was a significant increase in the rate of airway-related complica­ tions as the number of laryngoscopic attempts increased (:::; 2 vs. >2).36·37 1hese complications included hypoxemia, regurgi­ tation, aspiration, bradycardia, and cardiac arrest.36-38

19

20

Pri n c i p l es of Ai rway M a n a g e m e n t

Contrary to the experiences reported by Rose and Cohen and Mort, Hung et al.39 noted that immediately choosing an alternate technique (e.g. , a lightwand device) when DL had failed was typically rewarded with rapid tracheal intubation. Complications were both rare and minor and generally attribut­ able to the preceding attempts at DL. Heidegger et al.40 reported on a protocol for management of both anticipated and unan­ ticipated difficult intubations that emphasized defaulting to the flexible bronchoscope early when difficult laryngoscopy was anticipated or observed. Applied in 1 3,248 intubations, the pro­ tocol failed in only six patients (0.045%) ; again this strategy was associated with minimal morbidity. Similarly, Combes et al.41 reported on the efficacy of an institutional protocol employ­ ing the intubating laryngeal mask and a "bougie" (Eschmann Tracheal Introducer) . One hundred cases of unanticipated dif­ ficulties occurred among 1 1 ,257 tracheal intubations. There were three deviations from the protocol and two patients were awakened without further airway management. The tracheas of all patients managed by the protocol were successfully intu­ bated and ventilated. Finally, Mort42 compared the outcomes of patients undergoing emergency tracheal intubation in his insti­ tution before and after the application of the American Society of Anesthesiologists (ASA) guidelines. The rate of cardiac arrest during emergency intubation was reduced by 50%. Connelly et al.43 noted that alternatives to DL were far more likely to be successful than persistent use of DL in setting of multiple failed attempts. It is clear that early conversion to adjuncts and alternatives to direct-vision laryngoscopy when DL proves difficult results in a higher salvage rate with low patient morbidity than persistent use of the direct laryngoscope. The evidence is that the choice of the alternative may be less important than the fact that it is a practiced alternative and chosen early in a planned approach when DL has proven to be difficult or has actually failed. • Is There a Pattern to the Way Airway

Practitioners Behave in the Face of a Difficult or Failed Airway?

Tracheal intubation is still predominantly performed orally under DL. Difficulties related to airway management largely involve failure to achieve tracheal intubation due to difficult DL. A number of innovative new tools for tracheal intubation have been presented in recent years, which address many of the factors that give rise to difficult DL.44 The direct laryngoscope is designed to facilitate tracheal intubation by establishing a line-of-sight from the mouth to the larynx. As has already been noted, there are multiple patient factors, which individually or in combination may conspire to obstruct a laryngeal view. The ability to predict all patients in whom it will be impossible to establish a line of sight during laryngoscopy is sufficiently imprecise that sole reliance on the laryngoscope to perform tracheal intubation is a precarious strategy. It is likely that reliance on limited conventional airway tech­ niques is a risk-enhancing behavior, which predisposes patients to increased rates of morbidity and mortality. There is evi­ dence that such behavior has been common among anesthesia

practitioners. Rosenblatt et al.45 surveyed a random sample of the active membership of the ASA. The survey presented difficult airway scenarios involving cooperative adult patients who required tracheal intubation and physicians were asked to identify their preferred management technique. In a scenario described as a patient with a history of previous difficult intuba­ tion, 60% of practitioners would induce general anesthesia and 59% would proceed with DL. Experienced practitioners tended to use higher risk induction techniques and were more likely to use the laryngeal mask airway (LMA) in situations commonly agreed to be unconventional or contraindicated. Use of alterna­ tive devices including the Bullard laryngoscope, a lightwand, and other adjuncts was uncommon, occurring in less than 5o/o in all scenarios. Jenkins et al.46 surveyed 833 Canadian anesthesiologists to assess difficult airway management, training, and access to airway equipment. Respondents were asked to indicate their management choices in 1 0 difficult airway scenarios. DL was the preferred technique overall, with the flexible bronchoscope being the second most commonly used device. More experi­ enced, male, and older practitioners were more likely to choose asleep induction for high-risk scenarios, a finding similar to that of Rosenblatt. Respondents were not asked to indicate their degree of comfort in using the alternatives that were chosen to manage the clinical scenarios described in the survey. Wong et al. surveyed Canadian anesthesiologists by mail regard­ ing their management preferences in two situations: difficult intubation and cannot intubate, cannot ventilate (now more commonly referred to as cannot intubate, cannot oxygenate [CICO] ) . In the difficult intubation scenario, the preferred alternative airway devices were lightwand (45%) , flexible bron­ choscope (26%) , and intubating LMA (20%) . Only 57% of respondents had encountered a CICO situation in real life. In the CICO scenario, preferred invasive techniques were needle cricothyrotomy (5 1 o/o) , open cricothyrotomy (28%), and tra­ cheotomy by surgeon ( 1 4%) . In general, anesthesia practitio­ ners had little experience with and were uncomfortable with open surgical airways, although those that had practiced on mannequins were more comfortable using them in patients.47 There has also been a substantial change in our thinking with respect to surgical airway management as presented in Chapter 1 . To review, in the past it was left to the airway prac­ titioner as to whether to perform a Seldinger technique or an open cricothyrotomy. In fact, it was taught that anesthesia prac­ titioners ought to preferentially select a Seldinger technique as using a needle as opposed to a scalpel was felt to be psychologi­ cally more acceptable. However, Lamb,48 Aslani,49 and Elliot50 demonstrated that fellowship trained and certified anesthesiolo­ gists cannot reliably locate the cricothyroid membrane in elec­ tive surgical patients, particularly if they are female or obese. Subsequently, the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society (DAS) in the United Kingdom (NAP4)34•35 identified that needle tech­ niques were often unsuccessful and open techniques were more successful, although in many instances in the NAP4 reports, surgeons were more likely than anesthesia practitioners to per­ form the open techniques. It is currently recommended that an open cricothyrotomy be performed in the CICO situation or

The A l g orith m s

that, in the event of problems with needle techniques, conver­ sion to an open technique take place.345 1 It is recognized that most anesthesia practitioners would likely be neither trained nor competent to do so at this time. Cricothyrotomy employed in the setting of a failed airway has become emblematic of airway management failure. It is now taught that if the airway practitioner considers a CICO situation even remotely possible that the cricothyroid space be identified and the incision line marked preemptively. In other words, should a cricothyrotomy be needed it is a deliberate "part of the plan" as opposed to "emblematic of failure." The psychology of this approach is compelling in motivating indi­ viduals to move earlier to a cricothyrotomy as soon as a CICO situation is identified. Analysis of the 2005 ASA Closed Claims Database and NAP4 identified delay in performing cricothy­ rotomy as substantial issues leading to poor outcomes. 34·35•5 2 Kristensen and Moller53 similarly assessed airway manage­ ment behavior, experience, and knowledge among Danish anes­ thesiologists by surveying all members of the Danish Society of Anesthesiologists. Respondents were asked if they had experi­ enced situations during anesthesia in which insufficient oxy­ genation had caused serious problems that could have been prevented by different airway management. About a quarter of those surveyed answered in the affirmative with 20% of reg­ istrars and 26% of specialists agreeing. When asked whether they would perform awake intubation if they expected a dif­ ficult intubation, 34% of registrars, 50% of senior registrars, but only 25% of specialists said that they would. Only 48% of registrars and 59% of specialists agreed that a previous difficult intubation was a reliable predictor of difficult intubation in the future. These high-risk attitudes and behaviors are especially concerning. Among the specialists, only 2 1 % use a lightwand at least once a year, 1 1 % a BL, and 7% a retrograde technique. Forty percent of specialists had intubated the trachea of an awake, spontaneously breathing patient 1 0 times or less in their career, and 23% of specialists had never done so using an FB. Finally, about half the registrars and a third of the specialists reported that they did not routinely have immediate access to an LMA when providing anesthesia. Ezri et al. 's54 more recent survey of American anesthesia practitioners suggests that there may be an increasing willing­ ness to use alternatives to the direct laryngoscope in airway scenarios perceived as high risk. However, Ezri also observed that such willingness persisted even when the anesthesia prac­ titioners acknowledged that they were neither comfortable nor experienced with the alternate technology that they proposed using in these difficult situations. Finally, although repeated reports in the past cited poor clin­ ical decision making by anesthesia practitioners in the setting of difficult airway (both anticipated and unanticipated) resulting in patient harm, evidence is beginning to emerge suggesting that there has been a change in the approach to airway care on the part of at least a segment of anesthesia practitioners; this change emphasizes greater and earlier conversion to the use of an alternative (emphasizing but not exclusively employing the VL) to the direct laryngoscope in the setting of unanticipated difficult intubation with lesser reliance on multiple attempts with the direct laryngoscope before conversion occurs.55

The evidence would also support the conclusion that practitio­ ners with greater experience using video-laryngoscopes achieve greater success with them. • What Is the Medical-Legal Experience with

Respect to Ai rway Ma nagement Fai l u re?

The largest series of published medical-legal cases involving airway management is that of the ASA Closed Claims Project. Data from the airway cases reviewed in the ASA Closed Claims Project were originally published in 1 990, with addi­ tional publications in 1 99 1 , 2000, 2005, and 20 1 1 .56-59 In the original ( 1 990) report, respiratory claims accounted for 34% (522/ 1 54 1 ) of all claims. Inadequate ventilation was the most common single event overall, accounting for 1 2.7% of all claims and more than a third of the respiratory claims. In the original report, esophageal intubation and difficult intubation claims occurred each at about half the rate of those for inad­ equate ventilation.56 Caplan et al.56 speculated that improved monitoring would reduce the incidence of inadequate ventila­ tion and esophageal intubation and enhanced training would reduce the occurrence of difficult intubation and its sequelae. In 2000, additional Closed Claims data was published in the ASA Newsletter.58 Respiratory claims then accounted for 1 7.9% of total claims (798/4459), half the original proportion. Inadequate ventilation and esophageal intubation by then had accounted for considerably fewer claims than in the first report but claims for difficult intubation were now responsible for 6.4% of total claims, 1 4% higher than in the original report. In 48% of the difficult intubation claims, some difficulty was anticipated preoperatively by the anesthesia practitioner. Despite this expectation of difficulties, the most common (69% of instances) management strategy employed in these situations was induction of anesthesia followed by persistent attempts at oral laryngoscopic intubation. A similar strategy of multiple attempts orally was employed in scenarios in which difficulty was not anticipated but encountered. Of the cases in which difficulty was anticipated, 69% eventually deteriorated into a "CICO" situation. Airway management was deemed to be below the accepted standard ofcare in 49% of the cases reported in the update. This is significantly higher than that seen for other claims in the database. An updated analysis of the closed claims relating to manage­ ment of the difficult airway was published in 2005.5 2 Two-thirds of the documented events took place during induction of anes­ thesia and the remaining third during surgery, extubation of the trachea, or recovery. Care was judged to be less than appropriate or substandard in nearly half of the difficult airway claims. In the claims with an anticipated difficult airway, the first strategy was still more likely to be intubation after induction of general anesthesia with ventilation ablated (6 1 %) than awake intuba­ tion (32%) . There was no difference in the outcome in claims when succinylcholine was used compared with those in which a non-depolarizing muscle relaxant was employed at induction. Awake intubation was attempted but unsuccessful in 12 claims, resulting in death or brain damage in 75% of these claims. In 5 of these 1 2 claims, airway difficulties arose when general anesthesia was induced after attempts at awake intubation were

21

22

Pri n c i p l es of Ai rway M a n a g e m e n t

abandoned. Finally, in claims in which an emergency airway situation developed, the outcome was worse with persistent attempts at intubation before attempting emergency nonsurgi­ cal ventilation or emergency surgical airway access. The final update was provided in 20 1 1 .59 Respiratory events accounted for 1 7% of total claims and the most common events leading to claims were difficult intubation, inadequate oxygenation or ventilation, and aspiration. Difficult intubation accounted for 27% of respiratory events reported from 1 990 to 2007. Airway injury was the fourth most common injury in claims accounting for 7o/o of all claims; in previous reviews, unanticipated difficult laryngoscopy and intubation were associated with airway injury. Cook et al.60 reported on the closed claims in the United Kingdom against the National Health Service between 1 995 and 2007. Of 84 1 relevant claims 95 ( 1 1 o/o) were related to dental damage, 7 1 (8%) were associated with airway man­ agement (excluding dental damage and 29 (3%) were associ­ ated with respiratory events) . Defining which cases are, from a medicolegal viewpoint, high risk is uncertain, but the clini­ cal categories with the largest number of claims were regional anesthesia, obstetric anesthesia, inadequate anesthesia, dental damage, and airway. Those with the highest overall cost were regional anesthesia, obstetric anesthesia, and airway, and those with the highest mean cost per closed claim were respiratory, central venous cannulation, and drug error excluding allergy. Although airway claims were relatively infrequent overall, they tended to be associated with some of the most severe outcomes and the highest costs to close. Claims involving airway management were also more likely to be associated with a permanent adverse outcome than others, and it is recognized that severe adverse outcomes can affect the j udgment as to the appropriateness of care. 59 However, criticism of care may be well founded as a preoperative airway review was not conducted (or recorded as having been conducted) in 25% of cases, 28% of practitioner's had no explicit plan for deal­ ing with anticipated difficulties, and 25% did not alter their conventional method of airway management despite recogniz­ ing the potential for difficulty. Furthermore, when difficulties were encountered, the most common management strategy was persistent nonsurgical attempts at tracheal intubation. In 69% of cases where difficulties were anticipated, a CICO situation arose. Finally, and significantly, no strategy for extubation was outlined in almost half of the cases in which the practitioner encountered difficulties intubating the trachea.59 NAP4 in the United Kingdom built on the earlier work of Cook.34·35 This year long study gathered patient cases of major airway complications in all 309 NHS hospitals in the United Kingdom. It identified cases from the operating room, inten­ sive care unit (ICU) , and emergency department (ED) . The authors defined major airway complications as those leading to death, brain damage, emergency surgical airway, or unex­ pected ICU admission. After final review, 1 84 cases were included: 1 33 from anesthesia, 36 from ICU, and 1 5 from the ED. Importantly, when it came to surgical airway, the study identified a high failure rate of percutaneous cricothyrotomy performed by anesthetists. Of 25 attempts, only 9 were suc­ cessful (36%) . An open surgical technique, often performed by a surgeon, was associated with a 1 OOo/o success rate of tracheal

cannulation, although not all patients survived. In total, 1 4 tra­ cheotomies were accidentally dislodged, all in the ICU, with a 50% mortality. Other important conclusions could be drawn from this landmark study: •

•

•

•

•

•

poor assessment and poor planning led to poor outcomes! if an awake intubation was indicated, it was a good idea to do it! repeated attempts at orotracheal intubation or EGO use were rarely successful, better to perform a surgical airway early! it was good to plan for failure! failure to detect carbon dioxide meant that the endotracheal tube was not in the trachea, even in the newly dead! and inhalation induction of anesthesia on adult patients with upper airway obstruction was a bad idea! So we are not alone in North America!

AI RWAY ALGORITHMS • Why Are Algorithms Usefu l in Airway

Management?

Automatic responses are not typical when we are confronted by rare events such as the "CICO" situation, or even many types of emergency airways. Therefore, fundamental to successfully managing the emergency or failed airway is the development of a systematic approach to clinical situations rarely encountered in day-to-day practice. Algorithms, decision trees, and mne­ monics feature prominently in these approaches and they must be evidence based and quickly and easily applied. It is fair to say that after years of formal medical education and practice, most of us harbor an aversion to algorithms. While it is recognized that rigidity stifles innovation and constrains personal prefer­ ence, adherence to sensibly constructed decision trees mini­ mizes variation, conserves valuable time, and has been shown to provide the greatest chance for success. Decision aids such as algorithms and mnemonics are meant to inform rather than dictate to the practitioner. The practitio­ ner is required to correctly identifY the clinical problem (i.e., a failed airway) before choosing the algorithm. The algorithm should be designed and validated to ensure a high degree of success, provided that it is applied in the correct clinical situa­ tion. Many of these situations occur relatively infrequently in clinical practice, and it is unlikely that practitioners will have an opportunity to generate rules for managing the situations based on experience alone. By providing a limited number of likely-to-be successful options, the algorithm can increase the likelihood of a good outcome. Reason61 has defined two basic mechanisms whereby prac­ titioners deal with critical incidents. The first is a rule-based solution, whereby on recognizing the event for what it is, one identifies and applies a solution that experience has shown will likely be useful in solving the problem. Recognizing the event involves a process called "similarity-matching"; based on identi­ fYing that the characteristics of the events are similar to those of past events (in a sense, pattern recognition) . The practitioner then decides upon a particular solution that is likely to be effective in solving the problem and resolving the threat. This presupposes

The A l g orith m s

that the practitioner has had sufficient experience with both the situation and the application of the rule to both immediately recognize the problem and to know which rule to apply. This ability constitutes what is called "expertise." Unfortunately, dif­ ficult and failed airways are encountered infrequently in prac­ tice, and the individual experiences of practitioners may have not been sufficient to earn them expert status. The second mechanism for dealing with critical incidents is to apply a knowledge-based solution. This is a ground-up, first-principle strategy whereby the practitioner, without signifi­ cant past experience with similar situations, attempts to find an appropriate solution. Not surprisingly, such strategies often involve multiple decisions, are time consuming, and when made under pressure of time, are more likely to fail. Many airway practitioners will not have sufficient experience with difficult and failed airway scenarios to have, of themselves, created a rule-based, organized approach to these airway dilem­ mas for which knowledge-based solutions may be inadequate. For this reason, preformulated airway algorithms are helpful in these situations and deserve to be considered by all airway prac­ titioners. It is probably safe to say that with the attention paid to airway management by anesthesia, emergency medicine, and EMS over the past two decades, there has been a general reduc­ tion in emphasis on algorithms as guides to action, though they remain valuable aids in teaching and learning difficult and failed airway management. Coincident with the development of the decision trees (strategies) and vital to airway management success is skill in the application of an array of devices and techniques (tactics) that can optimize clinical outcomes. Techniques and devices advocated in this chapter, as in the case of the decision trees, are anchored by evidence and expert opinion, rather than personal preference. Algorithms meant to guide practice in crisis situations must exhibit the following design elements: •

•

•

•

•

•

Entry and exit points are easily recognized. They are based on the best available evidence. Branch points are binary. There are a limited number of actions at each step. They are easy to remember and represent graphically. Not all algorithms are intended as practice guides, rather as a graphic representation of an overall strategy (e.g., the ASA Algorithm) .

• What Are the Strengths a n d Wea kn esses

of the ASA Difficult Ai rway Algorit h m s a n d H ow Have They Evolved Over Ti me?

The ASA, in an attempt to avert airway management disas­ ters, has produced the ASA Difficult Airway Algorithm first in 1 993 (Figure 2- 1) , a revision in 2003 (Figure 2-2) and again in 20 1 3 (Figure 2-3) .62-64 All iterations of the ASA Difficult Airway Algorithm are derived from the Practice Guidelines for the Management of the Difficult Airway, developed by the ASA Task Force on Difficult Airway Management. In all three iterations, Panel A is directed at anticipating and managing the difficult airway, and Panel B deals with the foiled

airway. The algorithms guide management strategies when dif­ ficulty is predicted and recommend rescue tactics in the event of failure. They emphasize the importance of possessing expertise in more than one airway management technique and that each time an airway is managed, the practitioner formulate a variety of backup plans should the primary plan fail (Plan B and Plan C) . As the ASA guidelines evolved from the first to the second iteration, a number of important changes were made. Guidance was offered to those anatomic elements that may prove useful in the evaluation of the airway (Table 2-3) , although no direction is given as to how to interpret the findings. The concept of a reassuring versus non-reassuring assessment was now included, with the recommendation that a non-reassuring assessment be a relevant factor in the construction of a plan for airway manage­ ment. The need for the continuous application of oxygen to the patient during management of the difficult airway was empha­ sized in the second iteration. Finally, the LMA for ventilation was moved from the emergency pathway of Panel B to an entry point determining whether the emergency pathway is entered. This change was likely due to the worldwide recognition that the LMA is an effective rescue device. The third iteration evolved somewhat further. The term LMA was replaced by the noncommercial term, supraglottic devices (SGD which has been used interchangeably with EGO by oth­ ers) . While the overall arrangement and construction of the 20 1 3 algorithm is very much the same as the 2003 Algorithm, there are substantive issues mentioned in the narrative: •

•

•

•

•

The disclaimer that this guideline is not meant to represent the standard of care is reiterated as the ASA does for all of their guidelines. It is clarified that this guideline applies to anesthesia practi­ tioners and those supervised by anesthesiologists. It is clarified that this guideline only applies during the con­ duct of an anesthetic, and by exclusion not to anesthesia practitioners called to manage airways outside the OR. An extubation strategy is recommended. VL is mentioned in the guidelines.

Importantly, the guidelines remain virtually silent on the management of the difficult pediatric and obstetrical airway. As with prior iterations, the recommendations remain substan­ tially expert based, as do most association guidelines. A number of other groups have generated evidence-based consensus guidelines for the management of the difficult air­ way.44·65 Some, such as the 1 998 CAFG guidelines and the 2004 DAS guidelines in the United Kingdom differ from the ASA guidelines in being relevant only to the unanticipated dif­ ficult airway. They are similar to the ASA publications in that they recognize the utility of alternatives to both BMV and DL for intubation as well as emphasizing the role of salvage plans and physician training with the alternative devices. All of the authorities and guideline developers have similar recommendations: •

If difficulty is anticipated (a non-reassuring airway assess­ ment) secure the airway awake. It is well appreciated that even following a careful assessment suggesting that an airway will not be difficult, some airways will be difficult to manage.

23

24

Pri n c i p l es of Ai rway M a n a g e m e n t

A

'

B

l

Awake intu bation

Intu bation attem pts after ind uction of general anesthesia

Ai rway a p p roached by

Ai rway secu red by

I n itial i n t u bation

I n itial i n t u bation

nonsurgical i n t u bation

s u rg ical access*

attem pts successfu l*

attem pts u n s u ccessfu l

t

l

�

From t h i s point onwards repeatedly consider

Fail

S u cceed*

!

l

t

Cancel case

the advisa b i l ity of:

1 . Retu r n i n g to spontaneous venti lation.

2 . Awake n i n g the patient.

3 . Ca l l i n g for help.

S u rg i c a l a i rway*

Consider fea s i b i l ity of other options (al

'

'

Nonemergency pathway

Emergency pathway

Patient a nesthetized, i n t u bation u n s u ccessfu l,

Patient a nesthetized, i n t u bation u n s uccessfu l,

�

mask ventilation adeq uate

mask venti lation i nadeq uate

Alternative a pproaches

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If mask

to i n t u bation (bl

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venti lation

I

becomes i nadeq uate

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i n t u bation attempt

!

S u rg i c a l a i rway*

Su rgery u n d e r

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patient(5

Normal mandibular opening in the adult is about 4 em, or at least 2 finger breadths, between the upper and lower inci­ sors.3·9 Decreased mandibular mobility and anatomic variants, in particular micrognathia, can make intubation under direct laryngoscopy difficult or impossible. • The Pharynx

The pharynx is a U-shaped fibromuscular tube which extends from the base of the skull to the lower border of the cricoid cartilage where at the level of the sixth cervical vertebrae in the adult it is continuous with the esophagus (see Figure 3- 1 ) . 2•3·5 Posteriorly, it rests against the fascia covering the prevertebral muscles. Anteriorly, it communicates with the nasal cavity, mouth, and the larynx at the naso-, oro-, and laryngopharynx,

45

46

Pri n c i p l es of Ai rway M a n a g e m e n t

mylohyoid

F I G U R E 3-1 1 . The fl oor of the mouth. (Reproduced with perm is­ sion from Fried m a n S M . Visual A n a tomy Head and Neck. New York, NY: Ha rper & Row; 1 970.)

respectively (see Figure 3- 1 5) _ 3.4 From the pharyngeal lumen outward, the wall of the pharynx consists of mucosa, sub­ mucosa (pharyngobasillar fascia) , muscle, and a loose areolar sheath (the buccopharyngeal fascia) .5 This buccopharyngeal fascia is the thin fibrous capsule of the pharynx, contains the plexi of pharyngeal veins and nerves, and is continuous with the areolar sheath of the buccinator muscles and the adven­ titia of esophagus. 2 ·3•5 Superiorly, it is attached to the base of the skull. 2 Edema associated with infection in the floor of the mouth, such as Ludwig's angina, is limited by the buccopha­ ryngeal fascia, can spread into the pharynx and larynx, and can

Lesser pe!tosal nerve

-------....

G� ------­ nerve (CN IX) IIBvet'Sing jugula.r IOiamen with intemal jugular vein

� to ------��--�:r�

slyloplwyngeus carotid

body -----�=--

and sinus

Pharyngeal branches on middle const�or

-----­

F I G U R E 3- 1 2 . D i stribution of the g lossop h a ryngeal nerve (C N IX).

lead to airway obstruction.3 ,4 The muscular layer of the phar­ ynx is made up primarily of three paired constrictor muscles that curve around the pharyngeal lumen and telescope into one another (see Figure 3- 1 6) . The inferior constrictor consists of an upper oblique part and a lower transverse part (the cricopha­ ryngeus) that is continuous with the esophagus and functions as an upper esophageal sphincter.3•5 The j unction of the pharynx with the esophagus is the narrowest part of the gastrointestinal tract and is a common place for foreign bodies to impacr.3•5 The nasopharynx extends from the posterior choanae to the tip of the uvula3•6 and forms a backward extension of the nasal cavities (see Figure 3-17) .3·5 It is bounded inferiorly by the soft palate.3-5 It communicates with the oropharynx at the pharyn­ geal isthmus, which is closed during swallowing by the soft pal­ ate, the palatopharyngeus, and a ridge of the superior pharyngeal constrictor at the level of the second cervical vertebra, the ridge of Passavant.3-5 The roof of the nasopharynx is formed by the sphenoid bone and curves into the posterior pharyngeal wall at the level of the atlas and axis.3 . 5 ,G The nasopharyngeal tonsils (ade­ noids) are located in the roof of the nasopharynx and can extend laterally.3 . 5 The Eustachian tube enters through the lateral wallY A prominent arch of the atlas vertebra (C I ) may protrude anteri­ orly into the nasopharynx and during nasal intubation, the endo­ tracheal tube can impact the mucosa and resist advancement at this level. 23 Rotation of the tube may facilitate passage around this prominence. However on occasion digital manipulation of the tip of the tube by the index and middle fingers inserted through the mouth may be required and this also may not succeed. If these maneuvers fail, or as an alternative, a soft nasal trumpet can be passed first through the nose into the pharynx beyond the anterior tubercle of the atlas. A nasogastric (NG) tube cut off at its proximal end can then be passed into the pharynx through the trumpet and the trumpet removed. A nasal endotracheal tube can then be passed over the NG tube beyond the tubercle of the atlas. The NG tube can then be removed and the endotracheal tube passed into the trachea. The airway caliber in OSA has been shown to be reduced at all levels of the pharynx, with the narrow­ est portion posterior to the soft palate. 19

--------+- Nerve 10 pharyngo­ tympanlc tube ...----'r-- Nerve to posterior wall of pharyngeal plexus

Pre pa ration for Awa ke I ntu bation

HEAD OR CONOYL£

.

-�. ·�. . .

.

. .

.

.

• .

.. . . . . . . .

��-:·d: ·: :< � ·t··· .: .

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.

.

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.. . .. "· .

.

. . ..

F I G U R E 3-1 4. The te m po ro m a n d i b u l a r joi nt, on sag itta l sect i o n . F I G U R E 3-1 3 . Latera l view of m a n d i ble.

B a s e o f s ku l l -.....=....,..;.,..;.;..,.o::'---;..;...;,.;;;.;..,.,. Pharyngeal tonsil --"'"'""�-_. Nasal septum ---+-+-:c:ii­ Nasal conchae --===�HI:Nasopharynx Open i n g of Eustachian tube Soft pal ate ---l'='""l Uvu l a ---....r,:!I­ Palatine tonsil -----'�• Root of tongue -------'� Epiglottis ------+

Oropharynx

Pro m i nence of hyoid bone """"'-----;; a n d thyroid carti lage horns

La ryngopharynx Prom i nence of -------'ro cricoid ca rti lage

Esophagus

F I G U R E 3- 1 5 . Opened posterior view of the pha rynx.

The oropharynx extends from the soft palate to the tip of the epiglottis3•4•9 and lies behind the mouth cavity and poste­ rior third of the tongue. The palatoglossal folds arch downward from the soft palate to the junction of the anterior two-thirds and posterior third of the tongue and provide the dividing line between the mouth and oropharynx (see Figure 3-9) .3·5 This oropharyngeal isthmus is completed by the soft palate and the

sulcus terminalis of the tongue.3•5 The palatine tonsils lie on either side of the oropharynx in the triangle formed by the tongue and the palatoglossal and palatopharyngeal arches. 3-5 These two palatine arches and the triangular area between them are called the fauces. 5 A fold of mucus membrane, the median glossoepiglottic fold, overlying the hyoepiglottic ligament, con­ nects the epiglottis to the tongue in the midline and the lateral

47

48

Pri n c i p l es of Ai rway M a n a g e m e n t

Foramen

Plerygopalali ne fossa

ovate

Superior con st rictor ---���� muscle

I nferior constrictor muscle

F I G U R E 3 - 1 6. The l atera l view of the p h a ry n g ea l m u scles. (Reprod uced with perm ission from C u m m i ng s CW. Oto l a ry n g o l ogy Head and Neck S u rgery. 3 rd ed. St. Lou i s, MO: Mosby; 1 998.)

F I G U R E 3-1 7. The med i a l view of the p h a ryngeal m u cosa . (Reprod uced with perm ission fro m C u m m i n g s CW. Oto l a ry n g o l ogy Head and Neck S u rgery. 3 rd ed. St. Lo u is, MO: Mosby; 1 998.).

glossoepiglottic folds (pharyngo-epiglottic folds)5 connect it to the lateral pharyngeal walls.35 The depressions formed between these folds are termed the valleculae5·6 and are considered to be within the oropharynx.6 During direct laryngoscopy, the Macintosh blade is inserted into the base of the vallecula to engage the hyoepiglottic ligament and thereby move the epi­ glottis anteriorly to expose the glottis. The laryngopharynx (also referred to as the hypopharynx) extends from the epiglottis to the lower border of the cricoid car­ tilage, and is continuous with the esophagus (see Figures 3- 1 5 and 3- 1 7) .3 ,4·16 The upper border of the laryngopharynx has been located at the tip of the epiglottis by some authors 2 •3·9•16•24 and the base of the epiglottis by others.6·2 5 The oblique inlet (aditus) of the larynx is bounded by the epiglottis, aryepiglottic folds, arytenoid cartilages, and the posterior commissure. 3•5·24 The cylindrical larynx itself bulges posteriorly into the center of the laryngopharynx creating a deep recess, the piriform fossa (or sinus) , on either side leading into the esophagus.3 .4 As seen during direct laryngoscopy, the larynx can be conceptualized to be a smaller cylinder eccentrically placed within and at the anterior aspect of the larger cylindrical pharynx. The piriform fossae are bounded medially by the free upper end of the lar­ ynx5 formed primarily by the quadrangular membrane6 and lat­ erally by the thyroid cartilage and the thyrohyoid membrane.35 Superiorly the piriform fossae are bounded by the lateral glos­ soepiglottic folds. 2 Sensation to the nasopharynx and oropharynx is supplied primarily by the glossopharyngeal nerve.3•5 The glossopha­ ryngeal nerve enters the neck in company with the internal carotid artery and the internal j ugular vein. 26 At the level of the styloid process, it leaves this position and winds anteriorly and inferiorly lateral to stylopharyngeus which it supplies (see Figure 3- 1 8) .8 The nerve then passes forward between the superior and middle constrictors and gives off pharyngeal branches as well as lingual branches to the posterior third of the tongue (see Figure 3- 12).8 Glossopharyngeal nerve blocks can be performed posterior to the midpoint of the palato­ pharyngeal fold or at the base of the palatoglossal fold in the mouth. The maxillary branch of the trigeminal nerve supplies sensation to the roof of the nasopharynx and contributes to the sensory supply of the soft palate and the adjacent part of the tonsil.3·5 The laryngopharynx receives sensory innervation from the internal branch of the superior laryngeal branch of the vagus nerve, which pierces the thyrohyoid membrane and runs in the submucosa of the piriform fossae. 3 This nerve also supplies sensation to the larynx above the level of the false or true cords. 5·8• 27-2 9 Cotton pledgers soaked in local anesthetic can be held against the mucosa of the piriform fossa using Kraus or Jackson forceps to produce a block of the internal branch of the superior laryngeal, or the nerve can be approached percuta­ neously. The glossopharyngeal nerve also supplies sensation to the upper portion of the laryngopharynx.6 Some authors state that the superior aspect (pharyngeal surface) of the epiglottis is innervated by the glossopharyngeal nerve, whereas the infe­ rior aspect (laryngeal surface) receives sensory innervation from the superior laryngeal nerve (SLN) . 2 8'30 Others have stated that both surfaces of the epiglottis are innervated by the superior laryngeal branch of the vagus. 27

Pre pa ration for Awa ke I ntu bation

• The larynx

The larynx is a complex structure made up of a framework of cartilages and fibroelastic membranes covered by a layer of muscles and lined by mucous membrane.3 ,4 It functions as an open valve during respiration, a partially closed valve during phonation, and as a closed value during swallowing and when increased intrathoracic pressure is required (Valsalva maneuver) . 2·3•6·16 The larynx extends from its oblique entrance to the lower border of the cricoid cartilage and bulges posteriorly into the laryngopharynx (see Figure 3 - 1 5) _3. 5 It is suspended from the hyoid bone which is itself attached to the mandible, tongue, and the base of the skull. 16 The laryngeal cartilages include the thyroid, cri­ coid, epiglottic and the paired arytenoid, corniculate, and cuneiform cartilages (see Figure 3-19) . The quad­ rilateral laminae of the thyroid cartilage meet in the midline anteriorly to form the laryngeal prominence (Adam's apple) and thyroid notch. Posteriorly, the border of the thyroid cartilage is free and prolonged into paired upper and lower horns. 5 •6 Superiorly, the thyroid cartilage is attached to the hyoid by the thyro­ hyoid membrane.3 Posteriorly the lower horns of the thyroid cartilage articulate with the posteriorly ori­ ented signet ring shaped cricoid cartilage. Anteriorly the thyroid cartilage is attached to the cricoid by the CTM, a suitable site for emergency surgical airway access in the adult. The cricoid cartilage is the only complete skeletal ring of the airway and can be used to provide cricoid pressure (Sellick's Maneuver) dur­ ing rapid sequence induction/intubation. The paired arytenoid cartilages articulate with the superior aspect of the cricoid cartilage posteriorly. The corniculate cartilages in turn articulate with the apices of the pyra­ midal-shaped arytenoids and are located within the aryepiglottic fold.3•6 The shallow depression between the two corniculate cartilages (the posterior commis­ sure) is a useful landmark during laryngoscopy.3•6 1he cuneiform cartilages are located lateral to the cornicu­ late cartilages and also lie within the aryepiglottic folds. The leaf-shaped epiglottis is attached to the thyroid cartilage inferiorly by the thyroepiglottic ligament, and to the hyoid bone superiorly by the hyoepiglottic liga­ ment. 3 1he remaining framework of the larynx consists of two paired fibroelastic membranes, the quadran­ gular and triangular membranes (see Figure 3-20) . 3·6 The quadrangular membrane spans the space between the lateral border of the epiglottis and the arytenoid cartilages.3·6 Its slightly thickened free upper edge forms the aryepiglottic ligament at the laryngeal adi­ tus, and its markedly thickened lower border forms the vestibular ligament (false vocal cord) .3• 5 The trian­ gular ligament is attached in the midline anteriorly to the thyroid and cricoid cartilages and extends posteri­ orly to attach to the arytenoid. 5 •6•19 1he inferior border of the triangular ligament is attached obliquely to the cricoid cartilage, whereas the upper border is free and

iDI . carotid

a.

l'l!Cutrtnf {G"'jiiCjCQ{

F I G U R E 3-1 8. The g lossopharyngeal nerve. (Reprod uced with perm ission from Fried m a n S M . Visual Anatomy. Head and Neck. New York, NY: Ha rper & Row; 1 970)

1\merior -.iew

Anterosuperior .., ifw

R ighl l.tl�r•l view

ibp I olC.ll rt• 9 5 % @ 6 minutes versus only one in the control popu­ 2 lation. Finally, the lowest saturation in the study oxygenated group was 94.3% versus 87. 7o/o in the control population. 1 2 5

CRICO I D PRESS URE • Discuss t h e Applied Anatomy o f Cricoid

Pressure

The cricoid cartilage is shaped like a signet ring with the narrow part of the ring being oriented anteriorly. The anterior arch of the cricoid cartilage is attached to the thyroid cartilage by the cricothyroid membrane. Laterally the cricothyroid muscles are situated in the cricothyroid gap (see Figure 3-23) . The inferior horns of the thyroid cartilage articulate with the lateral surfaces

of the cricoid cartilage. The cricoid cartilage is attached to the first tracheal ring by the cricotracheal ligament. The esophagus begins at the lower border of the posterior aspect of the cricoid cartilage. Sellick4 proposed the application of CP during induc­ tion of anesthesia, to prevent regurgitation of gastric or esopha­ geal contents by compressing the esophagus between the cricoid and the cervical spine, obliterating the esophageal lumen. To perform the maneuver, the neck was extended, increasing the anterior convexity of the cervical spine and stretching the esophagus. Sellick hypothesized that this prevented lateral dis­ placement of the esophagus when CP was applied. However, Vanner and Ptyle1 26 reported that contrast CT scanning in one patient revealed that when CP was applied, although the cricoid cartilage and cervical vertebrae were approximated, only part of the esophageal lumen was obliterated. Smith et al. 1 27 reviewed 5 1 cervical CT scans of normal patients to assess the anatomic relationships between the cricoid cartilage and the esophagus. Lateral esophageal displacement relative to the cricoid cartilage was evident in half (25 of 5 1 ) of the patients; 64% of those with lateral displacement had esophageal displacement beyond the lateral border of the cricoid cartilage. Smith subsequently reported on MRI taken of 22 volunteers with and without CP applied. The esophagus was again seen to be displaced laterally relative to the cricoid cartilage in 52.6% of the subjects; this increased to 90.5% with the application of CP. Lateral laryn­ geal displacement and airway compression were observed in 66.7% and 8 1 o/o of the necks, respectively, with the applica­ tion of CP. 1 2 8 Boet et al. 1 29 studied esophageal patency with and without CP in 20 conscious volunteers using MRI. Target CP was achieved in 1 6 of 20 individuals, corresponding to a mean percentage reduction in crico-vertebral distance of 43% (range 25o/o-80o/o) . Incomplete esophageal occlusion was seen in 1 0 o f 1 6, o r 62. 5 % o f individuals when what was deemed to be appropriate CP was applied. Incomplete esophageal occlusion was always associated with a lateral deviation of the esopha­ gus. Rice et al. 1 30 investigated the anatomic impact of CP in 24 awake adult volunteers using MRI with and without applied pressure. With CP applied, the mean anterioposterior diameter of the hypopharynx was reduced by 3 5 % and the lumen likely obliterated, and this compression was maintained even when the cricoid ring was lateral to the vertebral body. The location of the esophagus was irrelevant to the efficiency of the CP with regard to the prevention of gastric regurgitation into the phar­ ynx. The magnetic resonance images showed that compression of the alimentary tract occurs with midline and lateral displace­ ment of the cricoid cartilage relative to the underlying vertebral body. Finally, Zeidan et al. 131 used real-time visual and mechan­ ical means to assess the patency of the esophageal entrance with and without CP in 1 07 patients who were anesthetized and paralyzed. Attempts to insert two gastric tubes (GT) into the esophagus were made by a "blinded" operator without and with CP, the timing of which was randomized while images were recorded with a GlideScope. A successful insertion of a GT in the presence of CP was considered evidence of a patent esophageal entrance and ineffective CP, whereas an unsuccess­ ful insertion of a GT was considered evidence of an occluded esophageal entrance and effective CP. Advancement of either size GT into the esophagus could not be accomplished during

117

1 18

Pri n c i p l es of Ai rway M a n a g e m e n t

CP in any patient but was easily done in all subjects when CP was not applied. This occurred whether the esophageal entrance was in a midline position or in a left or right lateral position relative to the glottis. Esophageal patency was visually observed in the absence of CP, whereas occlusion of the esophageal entrance was observed during CP in all patients. The efficacy of the maneuver was independent of the position of the esopha­ geal entrance relative to the glottis, whether midline or lateral. There is a potential for lateral positioning and displacement of the esophagus relative to the cricoid cartilage and this may possibly explain case reports where, despite the application of CP during RSI, regurgitation and aspiration occurred.81 It is also possible that the failure to prevent aspiration was attrib­ utable in some of these instances to the improper application of the technique rather than the failure of the technique. The esophageal lumen may be occluded with the application of CP even when the esophagus rests partially lateral to the midline or is displaced laterally with the pressure application and some of the effect of the applied pressure in occluding the lumen of the upper gastrointestinal tract may occur at the hypopharynx. • What Is the Sellick Technique?

Sellick132 outlined a number of steps in his original descrip­ tion of CP applied concurrently with anesthetic induction. The patient was placed in the tonsillectomy position with the cervical spine in extension. Before induction of anesthesia, the cricoid was palpated and lightly held between the thumb and index finger; as induction commenced, pressure was exerted on the cricoid cartilage mainly by the index finger. As the patient lost consciousness, Sellick recommended firm pressure sufficient to seal the esophagus. CP was initially felt to be contraindicated by Sellick in the setting of active vomiting, in the belief that the esophagus may be damaged by vomit under high pressure. He later modified this stand, stating that he felt the risk of rupture to be almost nonexistent. 1 32 Since his original description, the technique has been exposed to much study and critique. Data have now accumulated to provide evidence to support many of Sellick's recommendations.

hematemesis represents as likely a cause, as the stomach adja­ cent to the area of esophageal injury was noted to be bruised and swollen during the surgery, suggesting a temporally more remote injury. There are a number of factors that would explain why CP cannot provide absolute protection against aspiration, in addi­ tion to the anatomic factors already outlined. The landmarks on the patient's neck may not be identified properly and, as a result, pressure not exerted on the cricoid cartilage itself CP may not have been commenced prior to induction, allowing for an interval between loss of consciousness and application of pressure, during which the patient is at risk for aspiration. Personnel may be inadequately trained. CP may be released inadvertently before the trachea is intubated and the cuff inflated. Finally, it may be difficult to maintain occlusive pres­ sures for prolonged periods and the maneuver may become less effective in preventing aspiration during instances of difficult intubation. There is evidence that CP may decrease the barrier pressure of the LES as well, increasing the risk of passive regurgitation. Tournadre et al. 134 showed that LES pressure decreased from 24 to 1 5 mm Hg at 20 N of CP and to 12 mm Hg when 40 N of CP was applied. There is a paucity of data to evaluate the role of CP in pre­ venting patient complications and evidence that it may make securing the airway more difficult in some circumstances. At present, it is still recommended as part of the airway algo­ rithm135 and in the opinion of the authors, still plays an impor­ tant role. • How Much Cricoid Pressu re Is Needed to

Prevent Gastric Regu rgitation?

Twenty newtons (N) of applied CP are probably adequate in many instances and 30 N is more than enough to prevent regurgitation into the pharynx in most patients. Pressures of greater than 30 N (approximately 3 kg, or 7 !b) are unlikely to be necessary.40·136-138 The originally described forces (40 N) would rarely be necessary to prevent gastric regurgitation.

• Does Cricoid Pressu re Reliably Protect

• How Do You Measu re the Performance of

There are no outcome studies confirming the clinical benefit of CP when used either in anesthesia or resuscitation. Brimacombe and Berrl9 cite numerous case reports documenting the occur­ rence of aspiration despite the application of CP. There are also multiple studies documenting a negative impact of CP on patient interventions, usually relating to airway management. There is also a single case report in the literature attributing rupture of the esophagus to CP. 133 It involved an elderly female subjected to laparotomy after repeated episodes of hemateme­ sis. The patient, who vomited on induction, was positioned laterally, CP was released, and the trachea was intubated after pharyngeal suctioning. At surgery, a longitudinal split was found in the lower esophagus. It was concluded, by the report­ ing authors, that the esophageal rupture represented an esopha­ geal inj ury attributable to the CP. However, the diagnosis of rupture of the esophagus as a result of the repeated episodes of

Meek et al. 139 investigated the CP technique of anesthetic assis­ tants. A large variation in the force applied (from < 1 0 N to > 9 0 N) was observed. Performance was improved markedly by providing simple instruction and further improved by practical training in the application of target force on a simulator. Meek et al. 140 also studied six operating room assistants performing simulated CP (on a model of the larynx) to determine how long and under what conditions CP could be sustained. Subjects were asked to maintain forces of 20, 30, and 40 N for a target time of 20 minutes, with the arm either extended or flexed; most could not do so. Mean times to release of CP varied from 3.7 minutes (flexed) to 7.6 minutes (extended) at 40 N, 6.4 to 1 0.2 minutes at 30 N, and 1 3 .2 to 1 4.6 minutes at 20 N, respectively. These findings suggest that the ability to gener­ ate forces sufficient to provide esophageal occlusion and airway protection is limited.

Against Regurg itation and Aspiration?

Cricoid Pressu re?

As p i rat i o n : R i s ks a n d P reve ntion

• Is Bimanual Cricoid Pressu re Better Than a

One-Ha nded Techniq ue?

Flexion of the head on the neck may occur as a result of CP and this may impede laryngoscopy. Bimanual (two-handed) CP with the free hand of the assistant placed behind and support­ ing the neck or alternatively, with the use of a small support placed behind the patient's neck, has been recommended to overcome the tendency to neck flexion. 141 However, Vanner et al. 142 found no benefit for laryngoscopy when a cushion was placed behind the neck to prevent neck flexion during the application of CP. Cook143 compared the view of the larynx at laryngoscopy in 1 2 1 patients with one- or two-handed CP applied. In 28 cases, the laryngeal view was better with one­ handed CP, and in 1 1 cases the laryngeal view was better with two-handed CP. In 8 1 cases, the view was unaffected by the type of CP applied. Two-handed CP was not demonstrated to routinely provide an advantage over the one-handed technique. Yentis144 also studied the effect of the two different meth­ ods of CP on laryngoscopic view in 94 patients and reached contrary conclusions to those of Cook. In 2 1 cases, a better laryngoscopic view was obtained with the bimanual technique; in 8 cases it was better with the single-handed technique; and in 65 cases the method of CP made no difference. The force applied may have some impact on both the amount of neck flexion and the balancing potential of a bimanual technique. In the study by Yentis, considerably larger forces were applied (50-5 5 N) than in either Vanner's (30 N) or Cook's (40 N) studies. It is possible that more neck flexion occurred with the larger applied force and more benefit was thus realized when a bimanual technique was employed. In summary, the technique of CP which produces the best laryngoscopic view in an individual patient cannot be pre­ dicted. However, an alternative technique should be considered if it is suspected that the technique of CP application is having a deleterious effect on direct laryngoscopy. • Does It Matter Which Hand Is Used to Apply

Cricoid Pressu re?

Cook et al. 145 assessed the cricoid force applied by trained anes­ thesia assistants, as well as the ability to maintain the applied force, and compared the two hands. Overall, the assistants applied a lower force than is classically taught but were able to maintain the force with either hand for a sustained period. The use of the left hand resulted in slightly lower applied forces but the differences were not felt to be clinically relevant. Thus, no recommendation can be made regarding position of the assis­ tants as it relates to the handedness of the CP. • How Does Cricoid Pressu re Affect Ventilation

and Airway I nterventions?

A concern about CP in general, and at higher applied pressures in particular, has been the potential for compromise of either the quality of the airway or the effectiveness of airway interven­ tions. 146-148 In a recent report of 23 failed intubations over a 1 7-year period in one maternity unit, CP was maintained during the failed intubation drill. 149 In 14 patients (60%) , ventilation

via a face mask was not difficult, indicating that CP was at least not harmful in these patients. In the remaining nine patients, ventilation was difficult in seven patients (30%) and impossible in two (9%) . Although some patients had laryngeal edema, it is possible that CP contributed to the difficult ventilation in these patients. 146 Vanner148 reported that difficulty breathing occurred in about half of awake patients with 40 N forces applied, and Lawes et al. 1 50 reported that aitway obstruction occurred in about 1 0%. Hartsilver and Vanner151 investigated whether airway obstruction is related strictly to the force applied or whether the technique of application was also relevant. They recorded expired tidal volumes and inflation pressures during mask-ventilation in anesthetized patients. Airway obstruction occurred in 2o/o of patients with pressure applied at 30 N, and in 35% with 44 N. If the force is applied in an upward and backward direction, obstruction at 30 N occurs in 56%. Aoyama et al. 15 2 assessed the effect of CP (prior to inser­ tion) on the positioning of and ventilation through the LMA. Ventilation was considered adequate in all patients in the group with no CP applied but in only 25% of those with pressure applied. Using a flexible bronchoscope, the glottis was visible below the aperture bars of the LMA in all patients when no pressure was applied, suggesting correct placement. Correct placement was evident in only 1 5% of patients who had the LMA placed with CP applied. Evaluation using a flexible bron­ choscope showed that the mask was not inserted far enough in the remaining 85% of patients. Radiographs taken showed that the tip of the mask in the no-CP group was located below the level of the cricoid cartilage (C6 or C7 vertebra) , whereas the mask tip in the CP group was above this level (C4 or C5) . Asai et al. 153 studied 50 patients to assess if the CP applied after placement of the laryngeal mask prevented gastric insuffia­ tion, without affecting ventilation. CP significantly decreased mean expiratory volume delivered through an LMA. This inhibitory effect was greater when the pressure was applied without support of the neck. CP also reduced the incidence of gastric insuffiation. In no patient was the mask dislodged. The inhibitory effect of CP on ventilation without support of the neck was greater than CP with support of the neck. MacG Palmer and Ball154 studied the effect of CP on airway anatomy in 30 anesthetized patients examined using a flexible bronchoscope through an LMA. They assessed the effect of 20, 30, and 44 N on the internal appearance of the cricoid and vocal cords. At 44 N, cricoid deformation occurred in 90% of patients and 50% had cricoid occlusion; 43% had cricoid occlusion at 30 N and 23% at 20 N. Associated difficulty in ventilation was present in 50% of patients and 60% had vocal cord closure with associated difficult ventilation, at forces up to 44 N.155-157 Smith and Boyer158 evaluated the ease of rigid fiberoptic (WuScope System) intubation in anesthetized adults receiv­ ing CP. Each patient had their trachea intubated under two conditions: with and without CP. An easy intubation occurred in 9 1 o/o of patients without CP and in 66% of patients with CP applied. CP compressed the vocal cords in 27% of patients and impeded tracheal tube placement in 1 5%. In three patients

1 19

1 20

Pri n c i p l es of Ai rway M a n a g e m e n t

(9%) , pressure had to be released in order to successfully intu­ bate their tracheas. Hodgson et al. 159 assessed the effect of application of CP on the success of lightwand (SurchLite) intubation in 60 adult female patients presenting for abdominal hysterectomy. All 30 patients allocated to intubation without CP were intubated successfully, at the first attempt, within a median time of 28 seconds. Lightwand intubation with CP was successful in 26 of 30 patients at the first attempt, but the median time to success­ ful intubation was significantly longer at 4 8 . 5 seconds. Three patients required two attempts for successful intubation and one could not be intubated with the lightwand, while CP was applied. Turgeon et al. 157 assessed the impact of CP on laryngoscopy and intubation, comparing the experience with and without applied pressure in 700 patients and found no appreciable effect on tracheal intubation success, laryngeal view, or time to tracheal intubation. However, Noguchi et al. , 160 in a study designed to examine the effect of CP on passing a bougie, reported that CP significantly worsened the laryngeal view. Finally Harris et al. 161 evaluated the effects of CP and laryngeal manipulation on laryngeal view using a Macintosh laryngoscope during pre-hospital airway management in 402 patients cared for by a physician led pre-hospital trauma service. The major­ ity (98 . 8%) of the tracheal intubations were successful on the first or second attempt and CP was maintained in most. In 22 intubations, CP was removed when difficulty was experienced and the laryngeal view improved in 50% of these. Bimanual laryngeal manipulation was used after CP release in 25 intu­ bations and the view improved in 60% of these. Backwards upwards rightwards pressure was applied in 1 4 intubations after release of the CP and the laryngeal view improved in 64%. Two patients regurgitated when CP was released. Both had prolonged periods of bag valve mask-ventilation and difficult intubations. The results suggest that CP should be removed if the laryngeal view obtained is not sufficient to allow immedi­ ate intubation but that, in a significant proportion of patients, the view will remain suboptimal, implying that the CP did not degrade the view in many. Further manipulation of the larynx is likely to improve the chances of successful tracheal tube place­ ment in many of these patients after the release of CP. Corda et al. 162 assessed the impact of CP on glottic visual­ ization during GlideScope video-laryngoscopy (GVL) in 1 00 patients undergoing general anesthesia. There was no difference overall in glottic grade when CP was applied with views improv­ ing in 39o/o of patients and worsening in 20%. However, glottic opening area was reduced when CP was applied compared to during video-laryngoscopy alone. There were no glottis views worse than a Grade 2b registered in any patient during the study. CP does not appear to compromise the effectiveness of the GVL. In summary, properly applied CP has a limited impact on the ability to ventilate the lungs, the quality of the airway real­ ized, and may decrease the effectiveness of airway interventions. As applied pressures are increased, the potential for compromise of both the airway and airway interventions is also increased. At the time of publication, CP remains in the difficult airway algo­ rithm of the ASA, the Difficult Airway Society guidelines of the

United Kingdom, as well as the guidelines from the Canadian Airway Focus Group. 135 However, emphasis is now on the release of CP if airway intervention becomes difficult. 135•163 • What Is the Im pact of Cricoid Pressure on

Cervical Spine Movement?

In the setting of potential or actual cervical injury, concerns have been expressed that the application of CP may result in cervical spine displacement, causing or worsening cord inj ury. Although CP is widely used during airway management in trauma settings, there are no data either affirming its safety or implying that it actually poses a risk. Gabbott164 assessed the impact of single-handed CP applied concurrent with manual in-line stabilization of the neck in a neutral position in 30 healthy patients undergoing general anesthesia with neuromus­ cular paralysis. Vertical displacement was measured from the midpoint of the neck (directly below the cricoid cartilage) , and mean neck displacement (vertebral) was 4.6 mm with a range of O to 8 mm. Gabbott then measured the effect of single-handed CP on cervical spine movement after applying manual in-line stabili­ zation in cadavers. 165 The median vertical displacement mea­ sured from the body of C5 was 0 . 5 mm (range 0-1 . 5 mm) . There was no disruption of the lines formed by the anterior or posterior borders of the cervical bodies. In this second study, Gabbott164 was unable to demonstrate that single-handed CP caused clinically significant displacement of the cervical spine in a cadaver model. Wood166 studied the effect of CP on the view obtained at direct laryngoscopy with concurrent cervical stabiliza­ tion maneuvers. Laryngoscopic view was best in the unre­ strained position, with 77.4% of these views being Grade 1 . More frequently, Grade 3 views were obtained in the presence of cervical stabilization with or without CP. When in the sta­ bilized position, application of CP improved the view in 26% of patients. Wood concluded that CP may actually improve the view of the larynx when the neck is stabilized even though it is often detrimental to the view in the absence of stabilization. In summary, there is no evidence which would either encourage or discourage the use of CP in the setting of real or potential cervical injury. However, its use in this setting is common and there is no evidence of harm caused. CP may actually facilitate laryngoscopy when cervical immobilization is employed, in much the same fashion that anterior laryngeal pressure does.

OTH E R CO N S I D E RATIONS • What Is the Aspiration Risk Associated with

the Use of Extraglottic Devices?

Most of the following discussion for extraglottic devices (EGO) (also known as supraglottic devices [SGD] ) will involve the LMA, which has the largest body of literature. It should be noted that the recent literature supports the use of second-gen­ eration EGO which include the LMA-Proseal, LMA-Supreme, Laryngeal Tube, and iGel, to name a few. An EGO ideally

As p i rat i o n : R i s ks a n d P reve ntion

should produce reliable first-time placement, high seal qual­ ity, separation of GI and respiratory tracts and, importantly, ability to intubate through the device with an optically guided technique. 167 The LMA has enjoyed decades of widespread use in anesthe­ sia worldwide and has been hailed for its ease of use, efficacy, and low incidence of complications. As its use expanded, so did the nature of its application and it began to be employed for positive pressure ventilation, prolonged anesthesia (more than 2 hours duration) , laparoscopic and non-laparoscopic abdomi­ nopelvic surgery, and for surgery in the prone position. These applications have been labeled nonconventional applications and as these patterns of practice have become more common, increasing concerns about aspiration are being expressed. Investigators have addressed these concerns in three ways: 1 . Esophageal pH probes have been employed to determine the incidence and extent of GER during anesthesia with LMAs in place; 2. Deliberate pharyngeal soiling has been used to measure the protection afforded to the respiratory tract by the LMA. Clinical studies have compared the incidence of reflux with LMAs, endotracheal tubes, and alternative airways; 3. Finally, retrospective series and case reports have addressed the incidence of aspiration associated with LMA use and describe the clinical events and sequelae when aspiration occurred. The bulk of the published literature refers to the LMA-Ciassic'" and more recently the newer iterations of the LMA, including the LMA-ProSear· (PLMA) and the intubating LMA (LMA-Fastrach'") . Roux et al. 168 studied esophageal reflux using esophageal pH probes in 60 patients administered anesthesia with either a face mask or an LMA. They concluded that the use of the LMA was associated with an increased incidence of gastric reflux in the lower esophagus, but not mid-esophagus, and that reflux was not influenced by either volume of air or pressure inside the LMA cuff. Joshi et al. 169 found no evidence of gastric content in the hypopharynx using pH probes in a study that compared the LMA with the endotracheal tube in spontaneously breath­ ing patients. Ho et al. 170 reported that the use of positive pres­ sure ventilation in a similar model did not increase the risk of reflux. Hagberg et al. 171 studied both reflux and tracheal aspira­ tion using pH electrodes measuring in the proximal and distal esophagus, as well as the trachea. The patients were managed with either an LMA or a Combitube'". No changes in esopha­ geal or pharyngeal pH were observed, but 1 2% of the LMA group and 4% of the Combitube group had pH changes in the trachea. No patient demonstrated clinical signs or symptoms of aspiration. Using pH probes, McCrory and McShane172 determined the incidence and level of reflux during spontaneous respira­ tion with the LMA and compared the supine and lithotomy positions. The pH was measured in both the esophagus and the bowl of the LMA. Reflux into the esophagus occurred in 38% of the patients in the supine position and 1 00% of the patients in the lithotomy position. A change in pH was also measured in the bowl of the LMA in 57% of patients in the lithotomy position, but was not seen in the supine patients.

Cheong et al. 173 compared the incidence of reflux and regur­ gitation in adults at the time of LMA removal and compared the incidence when two strategies were employed for removal. In one group, the LMA was removed when signs of rejection were observed (swallowing, struggling, restlessness) and in the second, when the patients could open their mouth to com­ mand. A pH probe was used to assess reflux and a gelatin cap­ sule containing methylene blue swallowed before anesthesia induction was used to identify regurgitation. Instances of reflux measured with the pH probe were more common in the late­ removal group. There were no regurgitation events observed in either group. Evans et al. 1 74 assessed the ability of the LMA-Proseal to isolate the respiratory tract from the digestive tract. Methylene blue-dyed saline was instilled into the hypopharynx via the drainage tube once the mask was in place in 1 02 patients. A flexible bronchoscope was used to view the bowl of the mask to assess for evidence of methylene blue. Although an effective barrier was observed in all patients initially, mask displacement occurred in two patients (2%) and dye leaked into the bowl of the mask. Verghese and Brimacombe175 surveyed the use of the LMA in 1 1 ,9 1 0 patients, with special emphasis on nonconventional use of the LMA, and the occurrence of airway-related complica­ tions. Of the 1 1 ,9 1 0 uses recorded 2222 were considered to be nonconventional. Eighteen of the 44 documented critical inci­ dents related to the airway included laryngospasm (8) , regur­ gitation (4) , bronchospasm (3) , vomiting (2) , and aspiration ( 1 ) . There was no difference between the rates of occurrence of critical incidents in conventional (0. 1 6%) versus noncon­ ventional (0. 1 4%) use of the LMA. Brimacombe and Berry176 performed a meta-analysis of the published literature relevant to the association of LMA use and aspiration. In the reviewed papers, there were three cases of aspiration in 1 2,90 1 patients with no death or permanent disabilities recorded. Keller et al. 177 described three cases of aspiration: the first death and the first case of severe permanent neurological injury associated with aspiration and the use of the LMA. All three patients were considered by the authors to be at increased risk of aspiration; two had previous gastric surgery and the third had a hiatus hernia. Keller also reported a literature review designed to assess risk factors for LMA-associated aspiration. Twenty case reports were identified in the literature. In 1 4 cases, there were factors that could increase the risk of aspiration, includ­ ing inadequate depth of anesthesia (7) , intra-abdominal surgery ( 3 ) , upper GI tract disease (2 ) , lithotomy position ( 2 ) , exchang­ ing the LMA (2 ) , a full stomach ( 1 ) , multiple trauma ( 1 ) , mul­ tiple insertion attempts ( 1 ) , obesity ( 1 ) , opioid use ( 1 ) , and cuff deflation ( 1 ) . I n summary, there i s evidence that gastric reflux into the lower esophagus occurs with some frequency during anesthesia provided with an LMA even in healthy patients without obvi­ ous risk factors. Reflux to higher levels of the esophagus or into the pharynx appears to be less common but does occur. It may be increased by patient positioning, such as the lithotomy and lateral decubitus positions. Although the LMA cuff may pro­ vide a protective barrier to refluxing materials, the barrier is not absolute and aspiration may occur even with a LMA-Proseal

1 21

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Pri n c i p l es of Ai rway M a n a g e m e n t

in place. The incidence of aspiration associated with LMA use seems low and not significantly altered when the LMA is used in an unconventional manner. However, it is likely that many cases of LMA-associated aspirations have occurred and gone unreported. When aspirations are reported, it is common that factors traditionally associated with a higher risk of aspiration are present. In the opinion of the authors, in situations where the patient is at an increased or high risk of aspiration, it would seem pru­ dent to employ alternate methods to the LMA when managing the airway. • Is It Safe to Use a Lig htwand I ntubation

Technique in Patients at Risk of Aspiration?

Light-guided intubation has proven its efficacy in many clini­ cal situations. Studies have shown that the technique is both safe and effective, with minimal trauma and its ability to secure the airway in clinical situations where anatomical features make the use of the laryngoscope less likely to be successful. Indeed, features that predict difficult laryngoscopy have little or no cor­ relation with the ease or difficulty of light-guided intubation.178 The question of the safety of this technique in the patient at risk of aspiration is one not well addressed in the literature. Only one paper159 exists which reviews the use of this technique in the presence of CP and RSI in a randomized trial and it suggests that the use of the device is hampered by the pres­ ence of CP. Sixty healthy patients were randomized into a CP group and a non-CP group. Of the non-CP group, there was a 1 00% success rate on the first attempt. In the CP group of 30 patients, only 26 were intubated on the first attempt, 3 on the second, and 1 failed. The conclusion was that the light-guided technique should not be used as a first-line choice for RSI. As discussed earlier, a failed or difficult intubation increases the risk of aspiration. Under circumstances where a difficult laryngoscopic intubation is predicted, one could argue that the use of a light-guided technique might represent a safer choice. Hung et al. 178 reported that the success of a lightwand device, Trachlighf• (see Chapter 1 2) was at least as good, if not better than, as the laryngoscope in a series of 950 patients random­ ized into Trachlighf" and direct laryngoscope intubation. In another study, Hung et al. 179 studied 265 patients deemed to be difficult laryngoscopic intubations. Of these, 206 were felt to be difficult either because of previously documented prob­ lems or anatomical factors predicting difficulty, such as cervi­ cal fusion, small mandibles, and limited mouth opening. The remaining 59 were unanticipated failed direct laryngoscopic intubations whose airways were secured with the light-guided technique. A total of two failures occurred, both of which could have predicted due to anatomical abnormalities that made the transillumination difficult (obese patients) . Clearly, clinical judgment is required. In addition, coughing and gagging in relation to prolonged attempts at laryngoscopy are as likely, if not more so, to expose the patient to the poten­ tial of aspirating than if the assistant releases CP momentarily to facilitate insertion of a lightwand device. Unfortunately, apart from the solitary paper cited above, there is not enough evidence to draw a firm conclusion.

• Is Awake I ntubation with an Anesthetized

Ai rway Associated with a Lower Risk of Aspiration Than U nder Genera l Anesthesia?

Airway anesthesia is a routine part of awake intubation. Many sources caution against these airway anesthesia techniques in the patient with a "full stomach," fearing that anesthetizing the upper airway impairs protective reflexes leaving the patient at risk should regurgitation occur. 180-183 The question then arises how should one proceed in a patient who has an anticipated difficult airway in the presence of the elevated risk of regur­ gitation? Only one relevant study181 has been published in 1 989. The tracheas of 1 2 3 patients at high risk for aspiration were intubated awake, but sedated, with a flexible broncho­ scope. In 1 1 4 cases, the vocal cords were anesthetized by either injection of 4% lidocaine through the working channel of the bronchoscope or by transtracheal injection of lidocaine. No local anesthetics were used on 1 5 occasions. Topical anesthe­ sia was applied to the oropharynx by benzocaine-amethocaine (Cetacaine) spray and benzocaine ointment for oral intuba­ tions. Patients having nasal intubations received topical 4% cocaine to the nasal mucosa. No incidences of aspiration were identified in this study. While many use propofol boluses for "awake" intubation, this technique must be used with great caution. Propofol and other sedatives, including dexmedetomidine, decrease LES tone, predisposing to aspiration. In addition, the patient with airway compromise may depend on voluntary muscle tone for airway patency. 183 Clearly, each situation is unique. An anesthetized airway in an awake patient can prevent gagging, retching, and coughing during intubation. In addition, the awake, cooperative patient maintains the LES tone, can anticipate vomiting, and assist in maneuvers to prevent aspiration, such as turning the head to the side, opening the mouth for suctioning, etc. 181 On the other hand, sedation can produce an uncooperative patient that in addition has depressed airway reflexes. In the patient at high risk for aspiration, one must weigh each technique carefully in securing an airway while minimiz­ ing the risk of aspiration. • How Should Aspiration be Managed?

When aspiration is suspected prompt measures should be taken to prevent further aspiration. The head of the bed should immediately be adjusted to a 30-degree head down position and the patient's head turned to the left side to facilitate drain­ age of secretions. The upper airway should be suctioned thor­ oughly. If the patient aspirates on induction, intubation should follow immediately with aggressive tracheal suctioning before ventilation, if possible. If intubation was not intended (as in procedural sedation) and the patient is spontaneously breath­ ing, then supplemental oxygen by face mask should be applied after suctioning as one prepares for further assessment.5.l84·185 As was mentioned earlier, damage to the lungs after the aspi­ ration of gastric contents occurs within seconds, with subse­ quent neutralization of acid within 1 5 seconds. Consequently, bronchoscopy is not indicated except to remove large particu­ late matter.

As p i rat i o n : R i s ks a n d P reve ntion

The decision to proceed with or cancel the surgery should depend on the severity of the aspiration, the patient's clinical status, and the urgency of the procedure. Once able to com­ municate, the patient should be notified that aspiration has occurred and observed for signs of pneumonitis and pneumo­ nia over the ensuing days. Since gastric acid normally prevents the growth of bacte­ ria, antibiotics are not indicated simply because aspiration has occurred. The incidence of progression to bacterial pneumo­ nia following chemical lung injury is unknown. Symptoms of pneumonitis include wheezing, coughing, dyspnea, and cya­ nosis. Further complications may include pulmonary edema, hypotension, hypoxemia, and severe ARDS. 26 Treatment of pneumonitis largely consists of supportive therapy, varying from simple oxygen supplementation to full ventilatory support. The ventilation techniques used are beyond the scope of this chapter, however the primary goals should be to promote oxygenation and prevent further lung parenchymal damage. As with most types of acute lung injury, avoidance of baro­ trauma by delivering low lung volume ventilation with less than 6 mLkg -l coupled with cautious use of PEEP are important. In a porcine animal model where acid aspiration was induced, high levels of PEEP lead to histologic evidence of more severe lung injury than did recruitment maneuvers. 1 86 • Should Corticosteroids be Administered

Following the Aspiration of Gastric Contents?

The use of steroids following aspiration has been historically based on theoretical considerations, which remain unproven. These relate to anti-inflammatory properties, stabilizing effects on lysosomal membranes, ability to reduce platelet aggregation, and an improvement of peripheral release of oxygen from eryth­ rocytes. 1 87 Studies conducted in the 1 960s, 1 970s, and 1 980s consistently failed to prove a benefit of high-dose steroids after aspiration . 1 88-190 Nevertheless, the practice continues26 despite a significantly higher death rate from secondary infections in the group receiving steroids.191 The use of high-dose steroids has not been proven effective and can adversely affect mortality in the critically ill popula­ tion.5·191 Therefore, its use in episodes of aspiration is not recommended. • Should Anti biotics be Administered

Empi rica l ly to Prevent Pneumonia Following the Aspiration of Gastric Contents?

The majority of literature on the treatment of aspiration pneu­ monia is related to the aspiration of colonized oropharyngeal secretions/6 not gastric contents. Treatment should focus on supportive care to maintain oxygenation followed by organism­ specific antibiotic therapy should bacterial pneumonia develop. The incidence of post-aspiration pneumonia is more common in debilitated patients with comorbid conditions, and patients who have been on ventilatory support, due to leakage around the tracheal tube cuff that occurs in these patients. The prophylactic use of antibiotics following aspiration has not been demonstrated to prevent pneumonia and is not

recommended. 192 Some exceptions may include patients with bowel obstruction26 and elderly or debilitated patients. 192 The choice of antibiotics varies according to the syndrome and the clinical situation. For example, institutionalized elderly patients with aspiration pneumonia more commonly have anaerobic microorganisms193 than other population. The recommendations for antibiotic selection change fre­ quently and current guidelines for antibiotic therapy should be consulted. Such guidelines have been published by the follow­ ing medical societies: American Thoracic Society, 194 Infectious Diseases Society of America, 195 Canadian Infectious Disease Society, 196 and the Canadian Thoracic Society. 196 Most com­ monly, it is recommended that antibiotic selection be guided by culture and sensitivity determinations. 26 • How Long Should the Patient be Observed

Following the Aspiration of Gastric Contents Episode?

In a retrospective study of the perioperative course of 1 72,334 patients receiving general anesthesia, Warner et al. 6 reviewed 67 cases of aspiration. Forty-two of these patients who were asymptomatic at 2 hours post-aspiration or procedure never manifested any sequelae, acute or delayed. Eighteen of these were day surgeries, and 1 2 were discharged home on the day of surgery. Twenty-four patients developed symptoms within 2 hours including cough or wheeze ( 1 7) , decrease in arterial oxygen saturation of > 1 Oo/o on room air (1 O), an increase in the A-a gradient > 300 ( 1 ) , or radiographic changes ( 1 2) . Of the 24 with symptoms, 1 8 required respiratory support or ICU admis­ sion, with 6 being ventilated for more than 24 hours because of the development of ARDS. Only one patient developed pneu­ monia and required antibiotics. Patients who have been discharged home after suspected episodes of aspiration should be informed of the symptoms of pulmonary complications and instructed to report them promptly should they occur.

S U M MARY The prevention of aspiration is a significant focus of the air­ way practitioner. Certain factors markedly increase the risk of this event occurring. Some are inherent to the patients them­ selves, primarily premorbid conditions known to predispose to aspiration, some related to the patients' pathology and planned intervention, such as emergency surgery, bowel pathology, high ASA risk scores, pregnancy, difficult airway, and decreased level of consciousness. Airway management in the semiconscious patient may lead to coughing and gagging during attempts to secure the airway, accounting for over 2/3 of the perioperative aspirations. Recognition of high-risk patients is important. Maneuvers to reduce gastric acidity and volume, both pharmacologically and with drainage, may have their role but need to be targeted to specific situations. Bile and particulate materials are poten­ tially as harmful to the lung as is the acid that tends to be the primary focus. Thus use of particulate antacids has been aban­ doned in the perioperative setting.

1 23

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Pri n c i p l es of Ai rway M a n a g e m e n t

Although the efficacy of the Sellick maneuver has come under recent criticism, it is still a standard of care in the pro­ tection of the airway at risk in airway algorithms. A well-trained assistant is crucial. Under conditions when it hampers intuba­ tion or ventilation, it should be emphasized that CP should be released. The wisdom of the use of EGO in the high aspiration­ risk patient, when other options are available, should be criti­ cally analyzed. Finally, in the unlikely event that aspiration does occur, guidelines that are evidence based should be used in the assess­ ment and management of these patients.

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Smith KJ, Ladak S, Choi PT, Dobranowski J. The cricoid cartilage and the esophagus are not aligned in close to half of adult patients. Can j Anaesth. 2002;49: 5 03-507. 128. Smith KJ, Dobranowski J, Yip G, Dauphin A, Choi PT. Cricoid pressure displaces the esophagus: an observational study using magnetic resonance imaging. Anesthesiology. 2003;99:60-64. 1 2 9 . Boer S, Duttchen K, Chan J, et a!. Cricoid pressure provides incomplete esophageal occlusion associated with lateral deviation: a magnetic reso­ nance imaging study. J Emerg Med. 20 1 2;42:606-6 1 1 . 1 30. Rice MJ, Mancuso AA, Gibbs C , Morey TE, Gravenstein N , Deitte LA. Cricoid pressure results in compression of the postcricoid hypopharynx: the esophageal position is irrelevant. Anesth Analg. 2009; 1 09: 1 546- 1 552. 1 3 1 . Zeidan AM , Salem MR, Mazoit JX, Abdullal1 MA, Ghattas T, Crystal GJ. The effectiveness of cricoid pressure for occluding the esophageal entrance in anesthetized and paralyzed patients: an experimental and observational glidescope study. Anesth Analg. 20 1 4; 1 1 8 : 5 80-586. 1 32. Sellick BA. Rupture of the oesophagus following cricoid pressure? Anaesthesia. 1 982;37:2 1 3-2 1 4 . 1 33 . Ralph SJ, Wareham CA. Rupture of the oesophagus during cricoid pres­ sure. Anaesthesia. 1 9 9 1 ;46:40-4 1 . 1 34. Tournadre J P, Chassard D , Berrada KR, Bouletreau P. Cricoid carti­ lage pressure decreases lower esophageal sphincter tone. Anesthesiology. 1 997;86:7-9.

1 3 5 . Law JA, Broemling N, Cooper RM , et al. The difficult airway with rec­ ommendations for management-part 2-the anticipated difficult air­ way. Can ]Anaesth. 20 1 3;60: 1 1 1 9- 1 1 3 8 . 1 36. Hein C, Owen H. Th e effective application of cricoid pressure. J Emerg Prim Health Care. 2005;3 ( 1 -2) . 1 37. Vanner RG, O'Dwyer JP, Pryle BJ, Reynolds F. Upper oesophageal sphinc­ ter pressure and the effect of cricoid pressure. Anaesthesia. 1 992;47:95-1 00. 138. Vanner RG, Pryle BJ . Regurgitation and oesophageal rupture with cricoid pressure: a cadaver study. Anaesthesia. 1 9 92;47:732-73 5 . 1 39. Meek T, Gittins N, Duggan J E . Cricoid pressure: knowledge and perfor­ mance amongst anaesthetic assistants. Anaesthesia. 1 999;54: 59-62. 1 40. Meek T, Vincent A, Duggan JE. Cricoid pressure: can protective force be sustained? Br j Anaesth. 1 998;80:672-67 4. 1 4 1 . Crowley OS, Giesecke AH . Bimanual cricoid pressure. Anaesthesia. 1 990;4 5 : 5 88-589. 142. Vanner RG, Clarke P, Moore WJ, Raftery S. The effect of cricoid pressure and neck support on the view at laryngoscopy. Anaesthesia. 1 997;52:896-900. 1 43 . Cook TM. Cricoid pressure: are two hands better than one? Anaesthesia. 1 996;5 1 :365-368. 1 44. Yentis SM. The effects of single-handed and bimanual cricoid pressure on the view at laryngoscopy. Anaesthesia. 1 997;52: 332-33 5 . 1 4 5 . Cook T M , Godfrey I, Rockett M, Vanner RG. Cricoid pressure: which hand? Anaesthesia. 2000; 5 5 :648-653. 1 46. Allman KG. The effect of cricoid pressure application on airway patency. J Clin Anesth. 1 995;7: 1 97- 1 99. 1 47. Moynihan RJ, Brock-Urne JG, Archer JH, Feld LH, Kreitzman TR. The effect of cricoid pressure on preventing gastric insuffiation in infants and children. Anesthesiology. 1 993;78:652-656. 148. Vanner RG. Tolerance of cricoid pressure by conscious volunteers. Int J Obstet Anesth. 1 992; 1 : 1 9 5 - 1 98. 149. Hawthorne L, Wilson R, Lyons G, Dresner M. Failed intubation revisited: 1 7-yr experience in a teaching maternity unit. BrjAnaesth. 1 996;76:680-684. 1 50. Lawes EG, Duncan PW, Bland B, Gemme! L, Downing JW The cricoid yoke-a device for providing consistent and reproducible cricoid pres­ sure. Br J Anaesth. 1 986;58:925-93 1 . 1 5 1 . Hartsilver EL, Vanner RG. Airway obstruction with cricoid pressure. Anaesthesia. 2000;55 :208-2 1 1 . 1 52. Aoyama K, Takenaka I , Sara T, Shigematsu A. Cricoid pressure impedes positioning and ventilation through the laryngeal mask airway. Can J Anaesth. 1 996;43: 1 035- 1 040. 1 53 . Asai T, Barclay K, McBeth C, Vaughan RS . Cricoid pressure applied after placement of the laryngeal mask prevents gastric insuffiation bur inhibits ventilation. Br J Anaesth. 1 996;76:772-776. 1 54. MacG Palmer JH, Ball DR. The effect of cricoid pressure on the cricoid cartilage and vocal cords: an endoscopic study in anaesthetised patients. Anaesthesia. 2000;55 :263-268. 1 5 5 . Levitan RM , Kinkle WC, Levin WJ, Everett WW Laryngeal view during laryngoscopy: a randomized trial comparing cricoid pressure, backward­ upward-rightward pressure, and bimanual laryngoscopy. Ann Emerg Med. 2006;47: 548-5 5 5 . 1 56. McNelis U , Syndercombe A , Harper I, Duggan J. The effect of cricoid pressure on intubation facilitated by the gum elastic bougie. Anaesthesia. 2007;62:456-459. 1 57. Turgeon AF, Nicole PC, Trepanier CA, Marcoux S, Lessard MR. Cricoid pressure does not increase the rate of failed intubation by direct laryngos­ copy in adults. Anesthesiology. 2005 ; 1 02:3 1 5-3 1 9. 1 5 8 . Smith CE, Boyer D. Cricoid pressure decreases ease of tracheal intuba­ tion using fibreoptic laryngoscopy (WuScope System). Can j Anaesth. 2002;49:6 1 4-6 1 9 . 1 5 9. Hodgson RE, Gopalan P O , Burrows RC, Zuma K . Effect o f cricoid pressure on the success of endotracheal intubation with a lightwand. Anesthesiology. 200 1 ;94:25 9-262. 1 60. Noguchi T, Koga K, Shiga Y, Shigematsu A. The gum elastic bougie eases tracheal intubation while applying cricoid pressure compared to a stylet. Can ] Anaesth. 2003;50:71 2-7 1 7 . 1 6 1 . Harris T, Ellis DY, Foster L , Lockey D. Cricoid pressure and laryngeal manipulation in 402 pre-hospital emergency anaesthetics: essential safety measure or a hindrance to rapid safe intubation? Resuscitation. 20 1 0;8 1 : 8 1 0-8 1 6. 1 62. Corda OM, Riutort KT, Leone AJ, Qureshi MK, Heckman MG, Brull SJ. Effect of j aw thrust and cricoid pressure maneuvers on glottic visualiza­ tion during GlideScope video laryngoscopy. jAnesth. 20 1 2;26:362-368. 1 63 . Ovassapian A, Salem MR. Sellick's maneuver: to do or not do. Anesth Analg. 2009; 1 0 9 : 1 360- 1 362. 1 64. Gabbott DA. The effect of single-handed cricoid pressure on neck movement after applying manual in-line stabilisation. Anaesthesia. 1 997;52: 5 86-588.

As p i rat i o n : R i s ks a n d P reve ntion 1 65 . Helliwell V, Gabbott DA. The effect of single-handed cricoid pressure on cervical spine movement after applying manual in-line stabilisation-a cadaver study. Resuscitation. 200 1 ;49:53-57. 1 66. Wood PR. Direct laryngoscopy and cervical spine stabilisation. Anaesthesia. 1 994;49:77 -78. 1 67. Cook TM, Kelly FE. Time to abandon the 'vintage' laryngeal mask airway and adopt second-generation supraglottic airway devices as first choice. Br J Anaesth. 20 1 5 ; 1 1 5 :497-499. 1 68 . Roux M, Drolet P, Girard M, Grenier Y, Petit B. Effect of the laryngeal mask airway on oesophageal pH: influence of the volume and pressure inside the cuff. Br} Anaesth. 1 999;82:566-569. 1 69. Joshi GP, Morrison SG, Okonkwo NA, White PF. Continuous hypopha­ ryngeal pH measurements in spontaneously breathing anesthetized out­ patients: laryngeal mask airway versus tracheal intubation. Anesth Analg. 1 996;82:254-257. 1 70. Ho BY, Skinner HJ, Mahajan RP. Castro-oesophageal reflux during day case gynaecological laparoscopy under positive pressure ventilation: laryn­ geal mask vs. tracheal intubation. Anaesthesia. 1 998;53:921 -924. 1 7 1 . Hagberg CA, Vartazarian TN, Chelly JE, Ovassapian A. The incidence of gastroesophageal reflux and tracheal aspiration detected with pH electrodes is similar with the Laryngeal Mask Airway and Esophageal Tracheal Combitube-a pilot study. Can } Anaesth. 2004;5 1 :243-249. 1 72. McCrory CR, McShane A]. Gastroesophageal reflux during spon­ taneous respiration with the laryngeal mask airway. Can } Anaesth. 1 999;46:268-270. 1 73 . Cheong YP, Park SK, Son Y, et a!. Comparison of incidence of gastro­ esophageal reflux and regurgitation associated with timing of removal of the laryngeal mask airway: on appearance of signs of rejection versus after recovery of consciousness. J Clin Anesth. 1 999; 1 1 :657-662. 1 74. Evans NR, Gardner SV, James MF. ProSeal laryngeal mask protects against aspiration of fluid in the pharynx. Br J Anaesth. 2002;88: 584-587. 1 75 . Verghese C, Brimacombe JR. Survey of laryngeal mask airway usage in 1 1 , 9 1 0 patients: safety and efficacy for conventional and nonconven­ tional usage. Anesth Analg. 1 996;82: 129- 1 33. 1 76. Brimacombe JR, Berry A. The incidence of aspiration associated with the laryngeal mask airway: a meta-analysis of published literature. J Clin Anesth. 1 995;7:297-305. 1 77. Keller C, Brimacombe J, Bittersohl J, Lirk P, von Goedecke A. Aspiration and the laryngeal mask airway: three cases and a review of the literature. Br J Anaesth. 2004;93: 579-582. 1 78 . Hung OR, Pytka S, Morris I, et a!. Clinical trial of a new lightwand device (Trachlight) to intubate the trachea. Anesthesiology. 1 995;83: 509-5 1 4 . 1 79. Hung OR, Pytka S, Morris I, Murphy M, Stewart RD. Lightwand intu­ bation: II-clinical trial of a new lightwand for tracheal intubation in patients with difficult airways. Can } Anaesth. 1 995;42:826-830. 1 80. Bourke DL, Katz ], Tonneson A. Nebulized anesthesia for awake endo­ tracheal intubation. Anesthesiology. 1 985 ;63:690-692. 1 8 1 . Ovassapian A, Krejcie TC, Yelich SJ, Dykes MH. Awake fibreoptic intu­ bation in the patient at high risk of aspiration. Br } Anaesth. 1 989;62: 1 3- 1 6. 1 82. Simmons ST, Schleich AR. Airway regional anesthesia for awake fiberop­ tic intubation. Reg Anesth Pain Med. 2002;27: 1 80- 1 92. 1 83 . Walsh ME, Shorten GO. Preparing to perform an awake fiberoptic intu­ bation. Yale J Biol Med. 1 998;7 1 : 537-549. 1 84. BenumofJL. Management ofthe difficult adult airway with special empha­ sis on awake tracheal intubation. Anesthesiology. 1 9 9 1 ;75: 1 087- 1 1 1 0 . 1 8 5 . McCormick PW. Immediate care after aspiration of vomit. Anaesthesia. 1 975;30:65 8-665. 1 86. Ambrosio AM , Luo R, Fantoni DT, et a!. Effects of positive end-expira­ tory pressure titration and recruitment maneuver on lung inflammation and hyperinflation in experimental acid aspiration-induced lung injury. Anesthesiology. 2 0 1 2; 1 1 7: 1 322- 1 334. 1 87. Wynne JW, Modell JH. Respiratory aspiration of stomach contents. Ann Intern Med. 1 977;87:466-474. 1 88 . Lee M, Sukumaran M, Berger HW, Reilly TA. Influence of corticosteroid treatment on pulmonary function after recovery from aspiration of gastric contents. Mt Sinai} Med. 1 980;47:34 1 -346. 1 89. Sukumaran M, Granada MJ, Berger HW, Lee M, Reilly TA. Evaluation of corticosteroid treatment in aspiration of gastric contents: a controlled clinical trial. Mt Sinai J Med. 1 980;47:33 5-340. 1 90. Wolfe JE, Bone RC, Ruth WE. Effects of corticosteroids in the treatment of patients with gastric aspiration. Am ] Med. 1 977;63 : 7 1 9-722.

1 9 1 . Bone RC, Fisher CJ Jr., Clemmer TP, Slotman GJ, Metz CA, Balk RA. A controlled clinical trial of high-dose methylprednisolone in the treatment of severe sepsis and septic shock. N Engl } Med. 1 987;3 1 7 : 653-658. 1 92. Johnson JL, Hirsch CS. Aspiration pneumonia. Recognizing and man­ aging a potentially growing disorder. Postgrad Med. 2003; 1 1 3:99-1 02, 1 0 5 - 1 06, 1 l l - 1 1 2 . 1 93 . El-Solh AA , Pietrantoni C , Bhat A , e t al. Microbiology of severe aspira­ tion pneumonia in institutionalized elderly. Am } Respir Crit Care Med. 2003 ; 1 67: 1 650-1 654. 1 94. Niederman MS, Bass JB Jr., Campbell GO, et a!. Guidelines for the ini­ tial management of adults with community-acquired pneumonia: diag­ nosis, assessment of severity, and initial antimicrobial therapy. American Thoracic Society. Medical Section of the American Lung Association. Am Rev Respir Dis. 1 993; 1 4 8 : 1 4 1 8- 1 426. 1 95 . Bernstein JM. Treatment of community-acquired pneumonia-IDSA guidelines. Infectious Diseases Society of America. Chest. 1 999; 1 1 5 : 9S- 1 3S. 1 96. Mandell LA, Marrie TJ, Grossman RF, Chow AW, Hyland RH . Canadian guidelines for the initial management of community-acquired pneu­ monia: an evidence-based update by the Canadian Infectious Diseases Society and the Canadian Thoracic Society. The Canadian Community­ Acquired Pneumonia Working Group. Clin Inftct Dis. 2000;3 1 : 383-42 1 .

SELF - EVALUATION QU ESTIONS 5 . 1 . How much cricoid pressure has been shown t o prevent gastric regurgitation? A. 10 N B. 20 N C. 30 N D. 40 N E. 50 N 5.2. Which of the following is NOT true about cricoid pres­ sure and airway techniques? A. The difficulty in ventilation using the LMA is depen­ dent on the amount of pressure applied. B. Cricoid pressure reduces the incidence of gastric insuf­ flation when using an LMA. C. Improper LMA placement can occur when cricoid pressure is applied. D. Ventilation via a face mask has not been shown to be affected by cricoid pressure. E. In the event of difficulty with laryngoscopy, cricoid pressure should be released. 5 . 3 . Which of the following is NOT a known factor that increases the risk of aspiration? A. Emergency surgery B. Timing of surgery C. Lack of fasting D. Pregnant patients E. Children

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C H A PT E R 6

Human Factors an d Airway Manage ment Peter G . Brindley

CAS E PRESE NTATION

1 28

I NTRO DUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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TEAMWO RK .

1 29

LEADERS H I P .

1 30

SITUATI ONAL AWAREN ESS . . .

131

MANAG I N G I M P E N D I N G AI RWAY DI SASTERS . .

131

CHALLENGES .

1 32

S U M MARY .

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SELF-EVALUATIO N Q U ESTI O N S . . . . . . . . . . . . . . . . . . . 1 32

CASE PRESENTATION A lady in her thirties presented for endoscopic sinus surgery and septoplasty. Preoperative assessment found only a congeni­ tally fused neck vertebra and use of nasal decongestant spray for long-standing sinusitis. Despite a slight restriction in neck movement, there was nothing to suggest a problem with air­ way management. For example, there was minimal restriction in neck flexion extension and rotation. Mouth opening and thyromental distance were normal, and the Mallampati was Grade II. An experienced and diligent anesthesia practitioner planned to avoid tracheal intubation by inserting a laryngeal mask air­ way (LMA) . However, following induction with a remifentanil infusion (0.3 mcg·kg- 1 min- 1) and propofol (200 mg) , the LMA could not be inserted. Fifty additional milligrams of pro­ pofol were given but repeated attempts (including two different

sizes of LMA) were also unsuccessful. By 2 minutes the patient's oxygen saturation had decreased to 75% and she looked cya­ nosed. By 5 minutes her oxygen saturation deteriorated to 40%. Administration of 1 00% oxygen using a face mask and oral airway failed to raise the oxygen saturation, and the heart rate decreased to 40 seconds. The anesthesiologist then administered atropine and succi­ nylcholine. He attempted tracheal intubation and was joined by a second anesthesia practitioner (who had additional air­ way training) . Laryngoscopy provided only a Cormack and Lehane Grade 3 view (meaning tracheal intubation is likely to be very difficult, if not impossible) . Other staff entered the room, including the surgeon. Between attempts at laryngos­ copy, patient ventilation was extremely difficult, despite use of a four-handed technique. At no point did anyone announce that this was a "failed airway," a "can't intubate, can't oxygenate" situation, or an "airway emergency." Both anesthesiologists made further unsuccessful laryngo­ scopic intubation attempts. The second anesthesia practitioner attempted tracheal intubation using a flexible bronchoscope but without success, and other staff collected additional equip­ ment including a tracheotomy set. Next the surgeon attempted intubation by direct laryngoscopy with an Eschmann tracheal introducer; he was also unsuccessful. By 20 minutes, an intu­ bating laryngeal mask was inserted which allowed partial venti­ lation. The patient's blood pressure and heart rate increased as did the oxygen saturation but not above 90%. Blind attempts were made to insert a tracheal tube through the intubating laryngeal mask (as the device is intended to work) and then using a flexible bronchoscope. The surgeon failed to pass the scope through the end of the LMA (a recog­ nized problem with this device) . After more than 30 minutes, it was decided to abandon the procedure and let the patient wake up. The LMA was removed and an oral airway inserted. Oxygen saturation gradually improved to 95%. The anesthesi­ ologist transferred her to the recovery room and told staff that

H u m a n Fa ctors a n d Ai rway M a nagement

he expected the patient to wake. Both anesthesia practitioners carried on to their next cases. While the patient did breathe on her own, her level of consciousness did not improve and her vital signs remained erratic. After at least an additional hour, a third anesthesia practitioner transferred the patient to an intensive care unit (ICU) . On ICU admission, it was clear that the patient had marked brain damage. Finally the ICU staff inserted a naso­ tracheal tube. Her clinical course failed to improve and led to her ultimate removal from the ventilator, and her death from anoxic brain damage.

I NTRODUCTION • Why Should We Focus on Human Factors in

Medical Crises Such as the Management of Difficult and Fai led Airway?

This chapter as well as a subsequent chapter on airway manage­ ment in the ICU patient (see Chapter 34) offer a basic primer on human factors as they relate to the management of diffi­ cult and failed airway. These chapters are important because nontechnical skills likely have the greatest impact upon patient safety and outcome.1'2 Similarly, inadequate crisis resource management (which includes teamwork, leadership, situational awareness, resource utilization, and communication) appear to be the most common reason for preventable error. 1 '6 To illus­ trate this point, it is worth emphasizing that the above case is not fictional: it is the tragic case of Elaine Bromiley. While it is impossible to say what would have happened if her manage­ ment had been optimized, there were many things that could have been done better? Regardless, the team "lost control"7 and it contributed to the death of a 37-year-old woman, wife and mother of two. It was the wish of her husband Martin, a pilot and expert in Aviation Human Factors, that she " . . . not die in vain." The hope is to offer practical insights from this case for those who manage the difficult and failed airway. In short, the true airway expert should understand that factual knowledge in isolation is rarely enough to rescue the patient-in-peril. It is, therefore, time that our "team dexterity" and "verbal dexterity" matched our manual dexterity. • Can I nsights be Learnt from Other High­

Sta kes Industries and Appl ied to the Management of Difficult and Failed Ai rway?

These two chapters, the second specifically focusing on com­ munication (given that it is likely the most important of the nontechnical skills) , offer crisis management strategies from other high-stakes professions. While, the idea of directly trans­ lating ideas from aviation to medicine can be oversimplified, health care workers ought to be open to usable insights, no matter their origin. This is especially important since health care has been a latecomer to the study of human factors and team dynamics. 1' 2 For example, human factors training has been compulsory for pilots since the 1 990s. Accordingly, avia­ tion currently offers the most readily available strategies regard­ ing how we can make a "science of reducing complexity," and a "science of team performance." The first lesson is that airway

management, much like aviation, is increasingly a team sport. Second, teamwork is rarely innate, and therefore should not be left to chance. The largest aviation disaster (to date) occurred in 1 977 when KLM 4805 and Pan Am 1 736 collided. Investigators concluded that it was wholly preventable, and occurred largely because cockpit crews had "failed to take the time to become a team." 1 Eerily similar is the clinical case presented above.7 As pointed out at the Bromiley inquest, she likely died not just because of difficulty intubating, but because her team "lost control." Of note, the inquest concluded that there was nothing lack­ ing in the staffing, training, facilities, preoperative assessment, anesthetic choice, the initial use of an LMA, or with tracheal intubation once the LMA failed. What was found was that despite being senior anesthesia practitioners and nurses, they failed to identifY (and verbalize) that they had a failed airway; they failed to expedite appropriate alternatives strategies, and they failed to sound the alarm. Ultimately, it was the patient (and her husband and children) who paid the price. Much like the KLM flight investigators summarized: it might have been "preventable . . . if they had taken time to become a team."1

TEAMWORK Teamwork is commonly defined as "cooperative efforts to achieve a common goal." It is more than simply subordinates obeying an "all-knowing leader." 2 Instead, it is about maximiz­ ing mental and physical problem-solving capabilities, such that the sum exceeds the parts. 2 Moreover, task demands (rescuing the patient) and social demands (running the team) work in parallel. This means that airway experts must manage both. 2 •8 Leaders need strategies to turn individuals into team players, and this starts with accepting that individuals will not share their abilities unless they feel "safe" to do so. 2 This does not mean that we no longer need hierarchy and leadership, but does mean we cannot create the teams that we want unless we create the culture that we need.8 Culture is complex. However, it includes the knowledge, beliefs, customs, and habits of a group, and it powerfully influ­ ences behaviors, attitudes, and action. 8 Culture cannot be forced and takes time to develop. Moreover, culture typically matters more than the latest greatest study: "culture eats data for breakfast." All these observations mean that true airway experts invest time in building a culture of safety before the air­ way disaster occurs. To do so requires that they understand the pros and cons of our medical culture. For example, acute care medicine has a laudable culture of patient-ownership and self­ reliance. However, like the western culture it mirrors, we typi­ cally focus on the individual agenda rather than the cohesion of the team. 2 Similarly, we typically presume that success results from individual efforts (and failure from individual shortcom­ ings), rather than the team, environment, or culture. 2 1his also means that we do not naturally ask for help, or naturally offer help, and that we commonly blame individuals not systems. 2'6•9 All these need to change. One of the most common team failings is the inability to optimize resource utilization including personnel. This matters because airway management requires a coordinated

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Pri n c i p l es of Ai rway M a n a g e m e n t

TABLE 6-1 .

Practica l Crisis Resou rce Ma nagement Strateg ies for the Difficu lt a n d Fa i led Ai rway

Tea m Factor C l i mate and c u l t u re

Esta b l i s h stru ctu re

C reate a sha red menta l model

C ross m o n itor

M a i nta i n res i l i e n ce

Recom mendation M o re "we" less "me" M ut u a l respect; ca l m a n d decis ive H i e ra rchy sti l l has a ro l e "What" i s rig ht n o t "who" i s rig ht Ass i g n ro les Ass i g n respo n s i b i l ities Esta b l i s h priorities Com m u n i cate t h ro u g h o u t E n s u re a l l o n "sa m e page" I nvite i n put w h e n poss i b l e Outl i n e p r i o rities I nfl u e n ce tea m e m otions M o n itor perfo r m a n ce M o n itor workload F l atte n the h i e ra rchy Encou ra g e feed back Routi ne practice sess i o n s Req u est feed back Encou ra g e d e b rief Prov i d e t i m e for ca s u a l i nteracti o n

combination of skills, opinions, medications, and technologies. More specifically, low functioning teams are less likely to assign roles and responsibilities; to hold team members to account; to articulate a position or a corrective action; to use check-backs, for example, "closed-loop communication" (see Chapter 34) ; to seek usable information as opposed to j ust "data''; to priori­ tize tasks; and to cross-monitor other team members. 2 In short, airway experts realize that a "team of experts is not an expert team" (see Table 6- 1) . 2

LEADERS H I P Good leadership i s often much easier t o recognize than t o define. In broad strokes, leadership provides structure to chaos such that it maximizes the team's outcome and the "sum exceeds the parts."8 A key leadership strategy is the "shared mental model" meaning that all team members have a common understand­ ing. In other words, team members are "on the same page." 2 This leads to a task-focused, rather than power-focused or ego­ focused team, as well as a structure that is adept at prioritizing duties, managing information, assigning roles, stabilizing emo­ tions, and building confidence. 2 If time allows, the team leader can invite members to suggest a mental model ("what should we do now?") because diverse inputs can provide a more comprehensive view. 2 •8 However, under time-pressure, the leader has to be dexterous enough to rapidly establish a reasonable mental model that members will support ("this is a failed airway, please do the following").3

Studies have shown that the best situational awareness and the shortest reaction time come from practice and prior exposure.8 As a result, we should look to regular airway simulation not as a luxury, but as key to developing team "reflexes."9 The greater the overlap in mental models, the more likely that team members will predict, adapt, and coordinate, even if dealing with stress or novelty. 2 It is also essential to regu­ larly update the mental model ("okay, the airway is secured; our next priority is . . . ") and to ensure that it still makes sense as new knowledge comes to light ("we have saturations below 90%: this is now a failed airway") . Task-assignment is usually specified by profession (e.g., anesthesia practitioners manage the airway and surgeons operate) . 2 1herefore this does not usu­ ally need to be negotiated in the mental model. However, if there is confusion (i.e., rwo anesthesia practitioners are present; both surgeon and anesthesia practitioner could perform crico­ thyrotomy) , then it needs to be explicitly stated by the leader: "Dr Jones, you intubate, Dr Smith you get ready to insert an extraglottic device"; "Dr Jones, you perform cricothyrotomy and I will assist." Without leadership, diffusion of responsibil­ ity can occur. Some tasks, typically the easiest, will be addressed by several people even though one would suffice. Other tasks, typically harder ones, remain undone. 2 It may be tempting to scream out blunt instructions, particularly under stress. However, in order to engage other highly skilled individuals, we are best to employ a calm but credible approach. 8 This is because leadership cannot be claimed: it needs to be earned. In return, leaders are empow­ ered by the team to be decisive, and, when necessary to over­ ride others. The quid pro quo is that good leaders empower the team to speak up, and make it clear that others' contribu­ tions are essential.8 In short, good leaders create a culture that focuses on "what" is right, not "who" is right. In this way, the best leadership style promotes a culture of safety, and a culture of teamwork. 2,4 Good leaders also routinely change the focus berween clinical task completion and team coordi­ nation. This reduces fixation errors and prevents overtaxing individual members . Good leaders know that relationship conflicts should not be resolved during an emergency (which is why a debrief is so useful) . 2 In contrast, task-related con­ flicts must be dealt with promptly. 2 Good leaders know that an inexperienced team can still function, but usually needs more direction. This means more hierarchy and centralized control. 2 '9' 10 As the team matures, so should the team structure. The leader can now create a culture where members learn to and feel free to volunteer relevant information, verbalize contingencies, and apportion responsibility (so called "explicit coordination") , 2 Mature teams also voice relevant concerns and ask critical questions. This "cross-monitoring," or "mutual-monitoring," is one way to flatten the team's authority gradient. 2 As teams mature they can anticipate each other's resource needs and actions, and can act with minimal talking (so called "implicit coor­ dination") . 2 Typically, the more routine the task, the more experienced its members, and the more familiar they are with each other, the less explicit coordination needs to be. If engaged in an unfamiliar task, or with unfamiliar members, more explicit coordination is required.

H u m a n Fa ctors a n d Ai rway M a nagement

SITUATIONAL AWAREN ESS Broadly defined, situational awareness encompasses how we perceive relevant cues (e.g. , oxygen desaturation) , how we com­ prehend their meaning (e.g., "the patient is worsening"), how we synthesize a mental model (e.g. , "the patient needs intubat­ ing"), and how we predict what should happen next (e.g., "we need to prepare for a possible surgical airway") . 1 1 • 1 2 Situational awareness requires "metacognition" : an aware­ ness and understanding of one's thought processes. For example, one technique used in counseling to minimize disruptive behavior encourages people to "H.A.L.T." : because thinking and actions can be impaired when you are Hungry, Angry, Late, or Tired? Similarly, airway practitioners can learn to calm them­ selves using breathing exercises (previously taught to soldiers) , by consciously slowing their own breathing rate (breath in for four; hold for four; out for four) , or through mental rehearsal and cognitive imagery (e.g. , thinking about an anticipated dif­ ficult airway the night before, on the drive to the hospital, or during the elevator ride) . 1 3-15 The first level of situational awareness involves the percep­ tion of stimuli. 2 This requires focused attention, recognizing that by focusing "here" we risk missing "there." Because of the avalanche of stimuli, we must make conscious and uncon­ scious decisions upon where to prioritize, and what to ignore (or postpone) . This can lead to fixation errors: where we focus our attention inappropriately and miss relevant cues (e.g. , you are so focused on the airway that you miss the cardiac dys­ rhythmia) . Fixation errors are especially likely to occur during stress because we experience cognitive tunnel vision (e.g., the repeated attempts to intubate during the Bromiley case rather than employing the surgical airway option) . Attention is like a searchlight: it indiscriminately illuminates both important cues and irrelevant noise. As complexity increases, the number of possible cues also increases. Unfortunately, like the diameter of the searchlight's beam, our attention is limited. This risks selection bias either because our attention is misdirected toward irrelevant stimuli or fails to identifY crucial cues. 2 • 1 1 • 1 2 Fortunately, we can mitigate attention bias. For example, there are two main types of attention: scanning vigilance and focus, and both are essential in an airway crisis. Scanning vigi­ lance is typified by prey where focus is routinely changed in order to be vigilant to the next threat.16 By constantly redirect­ ing attention and sampling different inputs, the likelihood of selection bias and fixation errors are reduced.3•5•1 2 During air­ way management, we scan the patient and the monitors, look­ ing for cues that suggest distress. Just like lifeguards who scan the beach, we avoid looking at just one spot. However, when danger strikes, the second type of attention takes over: focus. This is typified by the focused gaze of a predator on a single prey, 16 or the life-guard who ignores others as he/she focuses on the person in distress. This is where nonessential stimuli are minimized and tunnel-vision supervenes. 1 7 This second type of attention minimizes waste, but has fixation error as a potential downside. The concern is that little is seen or heard outside of one's immediate focus. For those unconvinced about human cognitive fallibil­ ity, an excellent book by Chabris and Simons reviews their

famous psychological experiment (also known as "the invisible gorilla'') .8 In brief, viewers are asked to watch a video and sim­ ply count basketball passes between actors wearing white and black shirts. Given the complex things that most profession­ als do in their daily jobs, this may seem elementary. However, regardless of seniority, typically only half are correct. This is because the others were distracted by an actor who walks into the video frame midway through. He is wearing a gorilla suit and spends 8 seconds pounding his chest. Typically, viewers see either the gorilla or get the number of passes correct, but rarely both. What is equally insightful is when the video is replayed, many refuse to believe that there was ever a gorilla on the original. In short, our attention is imperfect, but so is our insight. The video demonstrates how we have blind spots in our vision (and in our j udgment) so that we only see what we are primed to see . 1 8

MANAG I N G IMPEND ING AI RWAY DI SASTERS • What Are the Basics of Decision Making and

Action, and How Could They Apply to the Difficult and Failed Airway?

In disasters, whether medical or otherwise, a three-phase sur­ vival arc appears to exist: denial, deliberation, and decision. 8 Preparation, whether through simulation or cognitive imagery or experience, decreases denial. It means that one has already done the work of deliberation, and that a cognitive-roadmap for decisive action is more likely to be applied. Expressed another way, how our brains respond depends greatly upon complexity and familiarity. So-called "automatic responses" occur imme­ diately because responses are embedded due to simplicity or repetition.1 2 For example, once the patient's oxygenation desat­ urates, they should be placed on "flush-oxygen" without much conscious thought. As such, our attention is freed up to con­ template next steps. "Simple decisions" occur rapidly when there are a few possi­ bilities, such as which laryngoscope blade to request. This occurs subconsciously in a second or two. "Complex decisions," such as the choice of airway rescue technique in the face a compli­ cated patient whose oxygenation continues to desaturate, take longer. That is because there is no preformulated response in one's personal database, and a response has to be created anew. In an emergency this consumes precious time. Finally, there is the "inability to make decisions" where no behavioral schema exists, and no temporary schema can be created. 19 1his typically causes stress, panic, or even paralysis. 2 As each team member builds an individual awareness (e.g. , observes something or thinks of something relevant) , they should report findings and plans back to the team leader. The leader then integrates these individual models into a shared mental model that summarizes the patient's current state (level two of situational awareness) and predicts their trajectory (level three of situational awareness) . In this way, the team's awareness amplifies each individual's awareness . Most of this is done through verbal communication, which, as stated above, is the subj ect of an entire subsequent chapter (see Chapter 34) .

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Pri n c i p l es of Ai rway M a n a g e m e n t

CHALLENGES • What Are the Challenges When Teaching

and Promoting Human Factors in Airway Management?

The "Semmelweis effect," 20 named after the doctor who was ridi­ culed for promoting hand washing, is the reflex-like tendency to reject new approaches because they conflict with established practice (i.e., "I have always approached the airway this way: why change now?") . In a similar vein, the Dunning-Kruger2 1 effect is a cognitive bias where unskilled individuals overestimate their ability, and where highly skilled individuals underestimate theirs. This means we are prone to erroneously assuming that tasks, like airway management, which are easy for them are easy for others. For all the above reasons, those promoting new approaches to the difficult airway are likely to encounter resistance.

S U M MARY As outlined, human factors and nontechnical skills may have the greatest impact upon patient safety and outcome in the management of difficult and failed airway. Moreover, improv­ ing our crisis resource management skills including teamwork, leadership, situational awareness, resource utilization, and com­ munication appears to be key to making airway management safer for our patients. These skills should not, and fortunately need not, be left to chance. Practical strategies can be readily borrowed from other high-stakes professions. As a result our "team dexterity" and "verbal dexterity" will match our manual dexterity and factual know-how. Teamwork is usually defined as "cooperative efforts to achieve a common goal." We need to understand that teamwork skills are neither innate nor typically promoted by traditional medical edu­ cation. As a result a "team of experts" is rarely an "expert team." This means that leadership skills are needed to provide structure to chaos. A key strategy is the "shared mental model," coupled with a credible but calm approach that appropriately prioritizes actions, integrates data, and controls emotions. Situational aware­ ness requires mastery in three domains: ( I ) how we perceive rel­ evant cues; (2) how we comprehend their meaning; and (3) how we synthesize a mental model to predict what might happen next. Studies suggest that there are three Ds in disaster: denial, deliberation, and decision. Practice, whether through clinical experience, cognitive imagining (mental rehearsal) , or through simulation are ways to reach the fourth 0, namely "decisive action," faster and safer. Regarding human factors and airway management, the question is not whether they matter (they clearly do!)-and not whether practical strategies can be applied (they certainly can!) but rather whether we have the humility and resolve to make the effort.

REFERENCES 1. Gawande A. The checklist. In: Gawande A, ed. The Checklist Manifosto. New York, NY: Henry Holt and Company; 2009:32-48. 2. St Pierre M. Hofinger G, Buerschaper C. Crisis Management in Acute Care

Settings: Human Factors and Team Psychology in a High Stakes Environment. New York, NY: Springer; 2008.

3 . Brindley PG, Reynolds SF. Improving verbal communication in critical care medicine. J Crit Care. 20 1 1 ;26: 1 5 5 - 1 59. 4. Gaba DM, Fish KJ, Howard SK. Crisis Management in Anesthesiology. New York, NY: Churchill Livingstone; 1 994. 5 . Gaba DM. Dynamic decision-making in anesthesiology: cognitive models and training approaches. In: Evans DA, Patel VI, eds. Advanced Models of Cognition for Medical Training and Practice. Berlin: Springer-Verlag; 1 992: 1 23 - 1 47. 6. Aron D, Headrick L. Educating physicians prepared to improve care and safety is no accident: it requires a systematic approach. Qual Saf Health Care. 2002; 1 1 : 1 68 - 1 73 . 7. Bromiley M. Just a routine operation (you tube) . Available at: http://www. youtube.com/watch?v=JzlvgtPiof4. Accessed July 20 1 5 . 8. Ripley A. The Unthinkable: Who Survives When Disaster Strikes-And Why. New York, NY: Crown publishers; 2008. 9. Brindley PG. Patient safety and acute care medicine: lessons for the future, insights from the past. Crit Care. 20 1 0 ; 1 4 (2) : 2 1 7-222. 1 0 . Heffernan M. Willfol Blindness: Why We Ignore the Obvious at Our Peril. New York, NY: Doubleday/Random House; 20 I I . 1 1 . Endsley MR. Toward a theory of situation awareness i n dynamic systems. Hum Factors. 1 995;37 ( 1 ) :32-64. 12. Endsley MR. Theoretical underpinnings of situation awareness: a critical review. In: Situation Awareness Anarysis and Measurement. Mahwah, NJ: Lawrence Erlbaum Associates; 2000:3-32. 13. What is tactical breathing. Available at: http://www.breathmastery.com/ what-is- tactical-breathing/Slow Breathing. Accessed July 20 1 5 . 1 4 . Immenroth M, Burger T, Brenner J, Nagelschmidt M, Eberspacher H, Troide H. Mental training in surgical education: randomized controlled trial. Am ] Surg. 2007;245 (3) :385-39 1 . 1 5 . Sanders C, Sadoski M , van Wlasum K, Bramson R, Wiprud R, Fossum TW Learning basic surgical skills with mental imagery: using the simulation centre in the mind. Med Educ. 2008;42 (6) :607-6 1 2 . 1 6. Proctor RN, Schiebinger L . Agnotology: The Making and Unmaking of Ignorance. Palo Alto, CA: Stanford University Press; 2008. 17. Stanton NA, Chambers PR, Piggott J . Review of situational awareness: concept, theory, and application. SafSci. 200 1 ;39(39) : 1 89-204. 1 8 . Chabris CF, Simons DJ. The Invisible Gorilla: And Other Wtzys Our Intuitiom Deceive us. New York, NY: Crown Publishers, Random House; 20 1 0 . 1 9. Leach J . Why people 'freeze' in a n emergency: temporal and cog­ nitive constraints on survival responses. Aviat Space Environ Med. 2004;75 (6) : 539-542. 20. Semmelweis Reflex. Wikipedia. Available at: http://en.wikipedia.org/wiki/ Semmelweis_reflex. Accessed July 20 1 5 . 2 1 . Dunning-Kruger Effect. Available at: https://en.wikipedia.org/wiki/ Dunning-Kruger_effect. Accessed July 20 1 5 .

SELF - EVALUATION QU ESTIONS 6. 1 . The inquest following the death o f Elaine Bromiley con­ cluded that: A. the anesthesia practitioner was grossly incompetent and should be sued for inability to intubate the patient. B. the nursing staff were grossly incompetent and should be fired for failing to sound the alarm. C. the surgeon was the best person to attempt intubation after the two anesthesia practitioners tried and failed to intubate. D. clearly the patient would have lived if teamwork had been better. E. the team "lost control" and failed to follow established guidelines for the failed airway. 6.2. Major categories in crisis resource management strategies include: A. leadership, communication, resource utilization, situ­ ational awareness B. hierarchy, obedience, implicit coordination, explicit coordination

H u m a n Fa ctors a n d Ai rway M a nagement

C. shared mental model, team dexterity, fixation error, communication

C. The Dunning-Kruger effect is the effect of a medical error on subsequent team performance

D. focus, vigilance, deliberation, communication, cross monitoring

D. The three Ds of a disaster survival arc are: denial, delib­ eration, decision

E. none of the above

E. The H .A.L.T. mnemonic means that you perform better if the team has Hierarchy; Aptitude; Lots of resources; and Training

6.3. Which of the following is true? A. Experienced teams need more explicit coordination; whereas inexperienced teams need more implicit coordination B. The "Semmelweis reflex" refers to the ability of people to learn new skills, but only once the rationale is prop­ erly explained

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136

CHAPTER 7

Context-Sensitive Airway Management Orlando R. Hung and Michael F. Murphy

CASE PRESENTATION ...........................

136

INTRODUCTION......................

137

AIRWAYMANAGEMENT TOOLS...................

139

CLINICAL APPLICATION OF AIRWAYMANAGEMENT TOOLS..

140

SUMMARY. SELF-EVALUATION QUESTIONS............

CASE PRESENTATION A 14-year-old girl is scheduled to have an excision of a man­ dibular mass in a hospital in Kigali, Rwanda. She is otherwise healthy, takes no medications, and has no allergies. She weighs about 42 kg and is 144 cm tall (BMI 20.3). On examination, she appears to be nervous, but cooperative. She has a large right mandibular mass restricting her mouth opening (3 cm) (Figures 7-1 and 7-2). She has a Mallampati IV score and jaw protrusion is limited, but, the range of motion of her cervical spine is normal. She agrees to have an awake intubation with some reluctance. Routine monitors (noninvasive blood pressure monitor, ECG, and pulse oximeter) are placed on her upon arrival at the operating room (OR). Intravenous (IV) access is established and a judicious amount of IV ketamine (bolus of 10 mg) is administered for sedation. Topical anesthesia is achieved with lidocaine sprays alone. Since a flexible broncho­ scope is unavailable, the following plans are prepared to secure her airway and communicated to everyone involved in her care. Plan A: blind nasal intubation using a BAAM (Beck Airway Airflow Monitor) whistle 1 ; Plan B: orotracheal intubation using

a video-laryngoscor. (0-MAQ; and Plan C: a surgical airway. Unfortunately, bli cl nasal intubation is not successful after a number of attem ts as the endotracheal tube (ETT ) repeatedly enters the e(c;p}iagus. Tracheal intubation using the C-MAC is also difficulr with poor visualization of the glottis, particularly whe die rosterior aspect of the tongue begins to bleed. With ongoing suction around the bleeding site, an attempt with direct laryngoscopic intubation also fails. It becomes obvious that the appropriate course of action is for the otolaryngologist to perform an awake tracheotomy under ketamine sedation and local anesthesia. With oxygen supplementation through a face mask (8 L-min-1) and repeated boluses of IV ketamine (1 0 mg), tracheotomy is secured while oxygen saturation remains above 90% during the procedure. Anesthesia is induced with thiopen­ tal and anesthesia is maintained with 1 to 1.5 MAC of halo­ thane. The otolaryngologist excises the mandibular mass and the patient is transferred to the intensive care unit in stable condition at the conclusion of the surgical procedure with ven­ tilation maintained through the tracheostomy tube.

FIGURE 7-1. Lateral view of a 14-year-old patient with a large right mandibular mass.

Context-Se n s itive Ai rway M a nagement

•

F I G U R E 7-2. Front view of a 1 4-year- o ld patient with a l a rg e right m a n d i b u l a r mass restricti n g her mouth o pe n i n g .

I NTRODUCTION The fundamental goals of airway management are the main­ tenance of adequate ventilation, oxygenation, and protection from aspiration. In the majority of clinical settings, these three goals are achieved in tandem, usually via orotracheal intubation using a conventional direct laryngoscope. As the location, time of day, skill set of the practitioner, and the devices available (i.e., the "context") change, the practitioner must be prepared to modifY his or her approach and employ alternative techniques as appropriate. Continuous oxygenation by whatever method possible takes precedence, particularly in emergency situations. • What Is Context-Sensitive Ai rway

Management?

The concept of "context-sensitive" airway management repre­ sents a paradigm shift in the approach to airway management. The skilled practitioner is less focused on specific devices and techniques, and is more aware of the context in which the patient presents and how that context influences the approach to airway management. The "context-defining" questions can be conceptualized as the "who, what, when, where, why, and how" which are unique to each airway management encounter. These questions, or con­ text modifiers, influence the decision making of a skilled airway practitioner. In a more pragmatic sense, examples of these con­ textual factors might include: •

•

•

•

•

the urgency of the case, availability of equipment (in the case presented, the practitio­ ner attempts blind nasal intubation because a flexible bron­ choscope is unavailable) , the expertise of an assistant or assistants, the time of day (influences the availability of additional skilled airway practitioners), the skill sets and personal experience of the practitioners (in the presented case, the skill set of the practitioner in blind nasal intubation, intubation using C-MAC, and the creation of a surgical airway) ,

the location in which the patient encounter occurs (in the presented case, resources such as airway equipment, drug availability, infusion pumps, etc. are limited in Rwanda) .

Patient factors, such as anatomy and physiology and the degree to which the patient can cooperate, conspire to influ­ ence the context of the situation. In the case presented, the 1 4-year-old girl is anxious, but cooperative. If she had been uncooperative, an awake intubation may not have been pos­ sible and her airway management would be quite different. Although a mask seal may be challenging in this patient, some practitioners may have considered inhalation induction of anesthesia or deep sedation using IV anesthetics maintaining spontaneous ventilation while performing tracheal intubation or tracheotomy, although caution in choosing this technique was recommended by the 4th National Audit Project of the Royal College of Anaesthetists of Great Britain and Ireland and the Difficult Airway Society (NAP4) . 2 • Which Tec h n i q u e Does the Context of

the Case Presented Suggest That S h o u l d be U s e d to Provide Ventilation a n d Oxygenation to a Ped iatric Patient w i t h a Difficult Ai rway?

The case presentation demonstrates how airway management by its nature, is context-sensitive. "Who, what, when, where, why, and how" are all context-defining questions that affect the way the airway management is best approached. In the case presented, the airway was successfully managed by a surgical tracheotomy, an option that may not have been considered by the same team in a different environment. In other words, the context has changed. Traditionally, bag-mask-ventilation (BMV) has been advo­ cated as the initial approach to a patient unable to independently sustain adequate gas exchange. Indeed, among the four domains of airway management (BMV, extraglottic device use, tracheal intubation, and surgical airway) , BMV has been the most com­ mon initial maneuver employed by most airway practitioners. Unfortunately, mounting evidence and opinion suggest that BMV is a difficult skill to master, particularly in the hands of nonexpert practitioners.3·6 In many cases, BMV is performed poorly with ineffective oxygenation and ventilation, and with gastric insuffiation being the end result. In the case presented, the use of BMV may be difficult because of altered anatomy (large mandibular mass) with disfiguration of the face. As extra­ glottic devices (EGDs) continue to improve in quality and ease of use, many experts agree that the placement of an EGD ought to supplant BMV as the initial technique of choice for the air­ way management of an unconscious and apneic patient, partic­ ularly by nonexpert airway practitioners? In the case presented, it may also be difficult to use an EGD as the device may not seat properly above the hypopharynx due to the altered anatomy. Clearly, no single device or technique can be relied upon as the sole modality for airway management by any practitioner. The choice of device and technique depends on the context of the situation. The airway management encounter in the case presented was likely to result in a failure of gas exchange using BMV or EGD, or any oral intubation approach. The

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Ai rway Tec h n i q ues

practitioner elected to employ nasal route options such as blind nasal intubation (in this case using a BAAM Whistle) , nasal bronchoscopic-assisted intubation, or nasal intubation using a lighrwand while at the same time preparing for surgical options. Unfortunately, neither a flexible bronchoscope nor a lightwand was available. A blind nasal approach is therefore reasonable with a surgical airway as an alternative plan. • H ow Has I n creasi n g Appreciation of

the Context-Sensitive Nature of Ai rway Man agement G u ided Tec h n o logical Adva n ces Lea d i n g to I m p roved Ai rway Man agement Tools?

Technological advances over the past two decades have dramati­ cally improved the quality and clinical utility of many airway management tools, including: 1 . The manufacturing and marketing of newer and improved EGDs for use in a variety of situations. 8 ' 9 Gone are the days where the LMA-Classic'M was the only, or even the preftrred, EGD for use in difficult or failed airways. In the United Kingdom, the iGel (lntersurgical Ltd.) has been the EGD of choice for pre-hospital airway management since 20 1 0. 10 The airway practitioner now has the option of choosing among devices that serve as tracheal intubation conduits in addition to those that have been shown to be effective rescue oxygenation devices in situations where intubation is not possible. 1 1 2. Advances in video resolution and LCD monitor technology, combined with high-quality color fidelity and optics have led to the development of several video-camera endoscopic­ based devices. These include the Glidescope• (Verathon Medical, Bothell, WA) , the Video Macintosh Intubating Laryngoscope System (C-MAC, Karl Storz Endoscopy Co., Culver City, CA) , and the McGrath• Series 5 and McGrath MAC Video-Laryngoscope (Aircraft Medical, Edinburgh, UK) . These devices remain subject to limitations due to fog­ ging, and obscuration of glottic visualization in the presence of blood, vomitus, or secretions. 1 2 Their utility remains ques­ tionable in these contexts (see Chapter 1 1 ) . Nonetheless, video-laryngoscopy continues to be an evolving field with intriguing possibilities in the absence of bodily fluids that may obscure their optics. 3. Improved portability of sophisticated airway management devices, coupled with the introduction of disposable variants, has broadened their utility. Devices are becoming more light­ weight, portable, and robust in construction. Battery-powered flexible endoscopes and compact video-laryngoscopes, such as the McGrath• Series 5 and McGrath• MAC, and the Glidescope• Ranger Video-Laryngoscopes, can be carried to the patient regardless of location and irrespective of external power sources or large video displays. 4. Enhanced light intensity of some airway instruments. The transillumination technique employed by lightwand devices, such as the Trachlight'M13 in the past, and new lightwand devices on the horizon, substantially improved with the use of high-intensity LED bulbs. 14 Adequate transillumination

is often possible under ambient lighting conditions, obviat­ ing the need to dim the lights or darken the room when these devices are being used. One study involving 950 patients demonstrated that nearly 88% of Trachlight'M intu­ bations were effectively accomplished under ambient light with or without simple shading of the neck. 15 5 . Reduction in cost in some of the newer video-laryngoscopes. While video-laryngoscopes have been shown to improve the laryngoscopic view and tracheal intubation success rates in patients with both normal and difficult airways, the cost of some of the devices is high and may be a barrier to their routine use. With the retail costs falling, some of the newer video-laryngoscopes (e.g. , the King Vision and the AirTraq) may become more affordable even for centers with limited resources (see Chapter 1 1 ) . • I n What Contexts Are Blind I ntubating

Techniq ues Indicated?

Over the years, direct laryngoscopic intubation has been shown to be an effective and safe technique that is relatively easy to per­ form. It has become the standard method of tracheal intubation in ORs, intensive care units, hospital wards, emergency depart­ ments, and in the field. Unfortunately, even in the hands of experienced laryngoscopists, the rapid and accurate placement of an ETT remains a significant challenge in some patients. This is particularly true in unprepared patients, or in situations where resources are limited, such as "austere" environments (see Chapter 59) in which blind or nonvisual techniques may be more practical and successful. Flexible bronchoscopic intubation has gained a measure of popularity as an alternative intubation technique over the past several decades. While effective and reliable, this technique requires expensive equipment, and special skill and training. Additionally, bronchoscopic intubation can be difficult in emergency situations in which unprepared or uncooperative patients may have copious secretions, blood, or vomitus in the upper airway. One large study involving more than 1 600 bron­ choscopic intubations recorded a success rate of approximately 94% in all comers. 16 The limitations of laryngoscopic intubation under direct vision, particularly under emergency conditions, have fostered the development of blind techniques using a variety of devices such as intubating guides and light-guided intubation using the principle of transillumination which have proven to be effec­ tive, safe, and simple. • Would It Not be Safer to Place a Tracheal

Tube Using a Technique That Is U nder Direct or Indirect Vision?

One would anticipate that the placement of an ETT into the trachea under direct or indirect vision using a laryngoscope or video-laryngoscope ought to be safer and achieve higher success rates than nonvisual techniques. Such is not the case: success and complication rates are not substantially different with blind techniques when performed by skilled practitioners, 15 as elabo­ rated below. It is well recognized that the technique of direct

Context-Se n s itive Ai rway M a nagement

or indirect vision intubation can be difficult or impossible in the face of difficult or distorted anatomy as illustrated in the presented case. In addition, contextual factors influence the suc­ cess rates and safety of indirect laryngoscopic intubation includ­ ing the inability to visualize the passage of the ETT through the glottic opening in the presence of blood, secretions, and vomitus. Many practitioners fail to understand that after having placed the flexible bronchoscope into the trachea under indi­ rect vision that the actual passage of the ETT over the bron­ choscope is done blindly employing the scope as a guide (see section "Define Blind Tracheal Tube Placement" in this chap­ ter) . In other words, during bronchoscopic intubation, after advancing the tip of the bronchoscope into the trachea, the bronchoscope functions only as a stylet to guide the ETT into the trachea similar to an Eschmann introducer. 17 The use of advanced airway devices to enable continuous glottic visual­ ization during ETT exchange has recently been reviewed. 1 8 This intriguing application o f these devices may b e applied to primary intubation to further increase the safety of blind intubation techniques, such as intubation over a bronchoscope, although further research is required. • Define Blind Tracheal Tube Placement

We define "blindness" as the inability of direct or indirect visualization of the glottic structures during tracheal tube placement. In the section above, we describe how intubation over a flexible bronchoscope is in fact performed blindly since the act of ETT passage through the glottis is not visualized. There are other airway management techniques that employ a similar application of the word blind. Even though direct visualization of the transilluminated light is employed to confirm placement of a lightwand into the trachea, neither the passage of the wand nor the passage of the ETT over the wand is visualized directly or indirectly. Blind nasal intubation is aided by the tactile sensation of expired gas against the cheek or the auditory assistance of a BAAM Whistle, but the passage of the ETT is not visualized. Finally, tactile digital intubation uses fingers to guide the ETT into the trachea in which passage of the ETT through the glottis is not visualized. Even when a direct or indirect laryngoscopy technique is employed, the actual passage of the ETT through the glottis may be blind (e.g. , a Cormack-Lehane Grade 3 view in which the ETT is inserted under the epiglottis blindly into the trachea with or without a bougie; or blood, vomitus, or secretions in the airway) . Many other procedures performed in medicine are in fact blind techniques including the placement of pulmonary arte­ rial catheters, arterial cannulae, epidural catheters, and femoral nerve sheath catheters. All of these procedures demand place­ ment blindly under the guidance of anatomical landmarks and physiological responses, although the recent introduction of sonography has changed the landscape of the performance of some of these procedures. 1 9 Blind intubating techniques have been shown t o b e effective and safe, and are acceptable methods of airway management when employed in the appropriate contexts.

AI RWAY MANAGEMENT TOOLS • Which of the EGOs Has Been Shown to

Provide Better Ventilation and Oxygenation and in What Contexts?

Implicit to any discussion about airway management tools and techniques is the realization that the best instrument for the situation depends entirely on the context. Unfortunately, there is no "one size fits all" device. The context affects a variety of issues when one contemplates the use of an EGO. These include: patient anatomy and pre­ dicted ease of insertion, full-stomach precautions and the need for airway protection from aspiration (e.g., Sellick's Maneuver) , need for positive-pressure ventilation, and the presence or absence of airway-obstructing pathology. These are just a few of the foctors which define the context of EGO use in airway management. In general, EGOs are best reserved for fasted patients at low risk of aspiration, and those with acceptable airways resistance and pulmonary compliance should positive-pressure ventilation be desired. However, EGOs are invaluable rescue devices in the case of unexpected airway management difficulty or failure. They have proven to be valuable as primary airway management devices in emergency medical services (EMS) . In these contexts, placement of an EGO with intubation capabilities and a parallel lumen for gastroesophageal venting may be advisable. In clinical practice, the actual device is less important than the thought­ ful consideration of all contextual factors. In the opinion of the authors, the EGOs currently available which best fulfill these objectives are the LMA-Supreme'" (non-intubating EGO) , the LMA-Fastrach'" (intubating EGO) , and the King LTS-0'". • What EGOs Should I Incorporate

I nto My Practice?

The most thoroughly studied EGOs currently in use are the Laryngeal Mask Airway and the Combitube'". Many competing designs and variations of these devices have been released to mar­ ket and are in use worldwide. We now have the option of using intubating LMAs as well as alternatives to the Combitube'", such as the King Laryngeal Tube Airway (King LT'", King Systems) which are placed blindly into the oropharynx and seated in the hypopharynx, directing respiratory gases into the trachea. In addition, a new generation of disposable, single-use EGOs has entered the marketplace, including the LMA-Unique (Teleflex) , Ambu LMA (Ambu USA) , and the i-Gel (Intersurgical Ltd) . Of particular use in the difficult or failed airway scenario are the various models of intubating LMAs such as the LMA-Fastrach'" and Air-Q® Intubating Laryngeal Airway (Cookgas) . Intubating LMA systems are fundamentally designed to permit the practitio­ ner to ventilate the patient and to provide a conduit for tracheal intubation. This may be accomplished using a flexible broncho­ scope, a lighrwand, or even by blind insertion. In the author's institution, an intubating LMA (LMA-Fastrach'") is kept in each anesthesia machine with the intention of immediate availability in the event of a failed airway or an airway emergency where other methods of preserving oxygenation have failed unexpectedly.

1 39

1 40

Ai rway Tec h n i q ues

The final consideration of note when deciding on the best EGDs to purchase and implement in one's institution is the differentiation between disposable and reusable devices. Several high-quality disposable EGDs are now on the market. These were developed partially in response to concerns of potential transmission of prion-based infection, such as Creutzfeldt­ Jakob disease (see Chapter 62) . Disposable devices, such as the LMA-Supreme'", may be best suited to use in the pre-hospital context where a reusable device requiring sterilization may be discarded or lost. Environmental concerns with the routine use of disposable devices are worth noting. • What Tracheal I ntubation Techniques

Should I Incorporate I nto My Practice?

Recalling the principles of context-sensitive airway manage­ ment, it is apparent that an expert practitioner should be comfortable with several techniques of tracheal intubation, including visual and nonvisual methods. For most practitioners involved in airway management, tra­ cheal intubation equates to direct laryngoscopy. It is true that the conventional laryngoscope, with interchangeable curved and straight blades, is likely the tool with the greatest recogni­ tion and use worldwide. Expertise with this tool is an essential skill for any airway practitioner. In addition, all practitioners should become familiar with the use of tracheal introducer, such as the Eschmann Tracheal Introducer or the Introes'M Pocket Bougie (BOMimed) . This device should be kept readily at hand wherever airway management and direct laryngoscopy may be required which includes the OR, emergency department, inten­ sive care unit, and in crash-carts throughout the hospital. Beyond direct laryngoscopy, the best tracheal intubation tool for an individual's practice depends on the context of that practice. Specifically, what types of patients do you routinely expect to see? Does your institution deal with "difficult" airway situations on a regular basis? How will budgetary constraints dictate which tools may or may not be available for purchase? While it is not possible to mandate a standard list of devices, it is reasonable to ensure access to a complementary armamen­ tarium of tools to confront the challenges that might arise. This should include laryngoscopes with curve and straight blades, the Eschmann Introducer, a flexible bronchoscope, a video-laryngoscope, such as the Glidescope•, Storz C-MAC, McGrath.MAC, or King Vision Video-laryngoscope (Ambu) , a nonvisual technique, such as a lightwand and an EGD with intu­ bating capacity. The remaining devices available should be con­ sidered on a case-by-case basis. A surgical airway kit, such as the Melker Emergency Cricothyrotomy Catheter Set-Universal (Cook Critical Care) or the H&H EmergencyCricothyrotomy Kit (H & H Medical Corporation) , is mandatory in all areas where airway management may occur.

CLIN ICAL APPLICATION OF AI RWAY MANAG E M E NT TOOLS There is a staggering array of airway management tools and techniques available today. For the average practitioner, it is unrealistic to expect proficiency with all devices. However, to

be a competent airway management practitioner, one must be familiar with a number of airway management tools and tech­ niques in order to be prepared for the inevitable challenges. • What Is the Most Appropriate Ai rway

Management Tool for an Unconscious Patient?

The simple answer to this question is whichever device restores ventilation and oxygenation promptly! A subsidiary concern is that the device protects against gastric insuffiation and aspira­ tion. These goals suggest that tracheal intubation is the most­ desired solution, currently most commonly achieved through direct laryngoscopy. However, in reality, the context will define the "best" way to manage an airway. In the example given at the beginning of this chapter, blind nasal intubation, direct and indirect laryn­ goscopy were not possible. A surgical airway as a planned alter­ native was performed. Traditionally, individuals charged with emergency airway management have been taught that BMV ought to be the initial airway management strategy in the unconscious patient. This paradigm may be shifting, particularly as evidence sup­ porting the ease of use and effectiveness of EGDs in the hands of those who infrequently manage the airway mounts. EGDs and BMV have similar drawbacks in that they leave the patient with an unprotected airway in terms of aspiration risk, and the ability to administer effective positive-pressure ventilation is variable. Overall, it is the authors' opinion that EGDs should be taught to rescue personnel because the authors believe that they are more effective and successful than BMV in most cases. All airway management practitioners ought to be familiar with the use of EGDs in appropriate patients, or as rescue devices in the setting of an intubation failure. • How Would You Manage Th is Patient if This

Patient Is Cya notic and Uncooperative?

The situation (context) has changed. The management of the uncooperative patient will be covered in detail in Chapters 3 5 and 4 2 . I n this case, the practitioner i s faced with the unenvi­ able decision as to whether or not to induce anesthesia with or without muscle relaxation in the face of a potentially difficult airway. In other words, should a rapid-sequence induction/ intubation (RSI) be performed? There is no simple answer to this question. In short, it is always desirable to have a controlled situation to permit exam­ ination and evaluation of the patient's anatomy prior to the induction of anesthesia or the start of an airway management procedure. Due to patient factors, this may not always be pos­ sible. In this context, one must judge whether maneuvers or interventions to correct the patient's cyanosis without invasive intervention are likely to succeed. These include administration of supplemental oxygen or simple airway maneuvers, such as a chin lift or jaw thrust. If these are unlikely to succeed, or are impossible due to the underlying pathology or the behavior of the patient, an RSI may be the only course of action while pre­ paring for an immediate surgical airway in the event of failure

Context-Se n s itive Ai rway M a nagement

(double setup) . In Chapter 2, the "forced to act" dilemma was discussed and may be considered in this situation. No mat­ ter the course of action employed as Plan A, calling for help, meticulous preparation for the primary plan, and preparation for several backup plans is critical. • What Other Factors I nfl uence the Selection

of an Airway Management Tool?

Successful context-sensitive airway management depends on the interplay between three general categories of modifiers. Each modifier demands a "who, what, where, when, why, and how" analysis. Consider the following: 1 . Practitioner foctors. These are factors unique to each airway practitioner and include, but are not limited to: degree of expertise, past experiences, ability to rapidly assess the needs of the situation, and the ability to modify or adapt one's approach to a dynamic and variable situation. In general, the skilled practitioner will be able to quickly assess a given airway management situation and select the most appropri­ ate technique from his or her personal arsenal of skills. 2 . Patient foctors. These factors are those unique to each indi­ vidual patient including, but not limited to: degree of cooperation, anatomical features pertinent to airway man­ agement (e.g. , a parturient) , size of the patient (children or morbidly obese patients) , medical comorbidities and past medical/surgical history, full stomach considerations, pres­ ence of blood or vomitus in the airway, lung compliance, airways resistance, and the anticipated need for aggressive positive-pressure ventilation. In general, the patient factors are "what the patient brings to the table." They refer to those things the practitioner may be able to modify. Patient fac­ tors must be considered for each individual for an airway management plan to be crafted that is best suited to that individual. There is no one sizefits all in airway management! 3. Situational foctors. This category refers to factors that are unique to the particular situation in which the airway must be managed. Situational factors include, but are not limited to: location of the encounter (e.g., pre-hospital vs. emergency department, etc.), urgency (elective vs. emer­ gency situations) , availability of skilled assistants, the airway management tools and equipment available, presence of confounding/complicating factors such as C-spine immobi­ lization collars, and availability of expert backup in the event of difficulty. The situational factors present in the environ­ ment where one practices may be modifiable to some extent. For example, a practitioner can petition the hospital to pur­ chase an airway management tool not currently available or advocate for higher standards of airway management train­ ing for pre-hospital care personnel.

S U M MARY The aim of this chapter is to introduce the concept of context­ sensitive airway management. The most fundamental dilemma facing the practitioner wishing to improve his or her dif­ ficult or failed airway management skills is making logical,

evidence-based, and clinically appropriate management deci­ sions. The case at the beginning of this chapter is based on the author's (OH) encounter during his participation in a Global Outreach Program in Rwanda. It is used as an example of the principles involved in context-sensitive airway manage­ ment. This case presented an airway management strategy for a patient with a difficult airway in an austere environment with limited resources. Gaining familiarity and experience with a variety of airway management techniques and devices will best equip the prac­ titioner for rhese inevitable and challenging situations. At rhe very least, a competent practitioner should be facile with the techniques of BMV, direct laryngoscopy and tracheal intuba­ tion, placement of an EGO, and performance of an emergency cricorhyrotomy. In addition, all practitioners should have prede­ termined plans "A," "B," and "C" when approaching any airway situation. The rare but extremely important can't intubate, can't oxygenate situation must be routinely considered.

REFERENCES 1 . Cook RT J r, Stene J K Jr. The BAAM and endotrol endotracheal tube for blind oral intubation. Beck Airway Air Flow Monitor. J Clin Anesth. 1 993;5 :43 1 -432. 2. Cook TM, Woodall N, Frerk C, Fourth National Audit P.Major compli­ cations of airway management in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society. Part 1 : anaesthesia. Br j Anaesth. 2 0 1 1 ; 1 06:6 1 7-63 1 . 3 . Augustine JA, Seidel DR, McCabe JB. Ventilation performance using a self-inflating anesthesia bag: effect of operator characteristics. Am } Emerg Med. 1 987;5 :267-270. 4. Lawrence PJ, Sivaneswaran N. Ventilation during cardiopulmonary resus­ citation: which method? Medj Aust. 1 98 5 ; 1 43:443-446. 5 . Lee HM, Cho KH, Choi YH, Yoon SY, Choi YH. Can you deliver accurate tidal volume by manual resuscitator? Emerg Med]. 2008;2 5 : 632-634. 6. Noordergraaf GJ, van Dun PJ, Kramer BP, et a!. Airway management by first responders when using a bag-valve device and two oxygen-driven resuscitators in 1 04 patients. Eur} Anaesthesia/. 2004;2 1 : 36 1 -366. 7. Petrar S, Murphy M, Hung 0. Is a seismic shift in EMS airway man­ agement coming? A closer look at oxygenation, ventilation, intubation & alternative airways. ]EMS. 2009;34:54-59. 8. Bogetz MS. Using the laryngeal mask airway to manage the difficult air­ way. Anesthesiol Clin North Am. 2002;20:863-870, vii. 9. Cook TM. The classic laryngeal mask airway: a tried and tested airway. What now? Br J Anaesth. 2006;96 : 1 49- 1 52. 10. Lockey D, Crewdson K, Weaver A, Davies G. Observational study of the success rates of intubation and failed intubation airway rescue techniques in 7256 attempted incubations of trauma patients by pre-hospital physi­ cians. Br ]Anaesth. 2 0 1 4; 1 1 3 :220-225. 1 1 . Gerstein NS, Braude DA, Hung 0, Sanders JC, Murphy MF. The Fastrach Intubating Laryngeal Mask Airway: an overview and update. CanJAnaesth. 2 0 1 0;57:5 88-60 1 . 1 2 . Sakles JC, Patanwala AE, Mosier J , Dicken J , Holman N . Comparison of the reusable standard GlideScope(R) video laryngoscope and the dispos­ able cobalt GlideScope(R) video laryngoscope for tracheal intubation in an academic emergency department: a retrospective review. Acad Emerg Med. 20 14;21 :408-4 1 5 . 1 3 . Hung OR, Stewart RD. Lightwand intubation: 1-a new lightwand device. Can ]Anaesth. 1 99 5 ;42:820-82 5 . 1 4 . Milne AD, D'Entremont M l , Hung O R . Optimum brightness of a new LED lightwand device in a cadaveric model-a pilot study. Can J Anaesth. 20 1 6;63 (6) :770-77 1 . 1 5 . Hung OR, Pytka S, Morris I, et al. Clinical trial of a new lightwand device (Trachlight) to intubate the trachea. Anesthesiology. 1 995;83:509-5 1 4 . 1 6. Heidegger T, Gerig HJ, Ulrich B, Schnider TW Structure and pro­ cess quality illustrated by fibreoptic intubation: analysis of 1 6 1 2 cases. Anaesthesia. 2003; 5 8 :734-739. 1 7. Hung OR. Misconception of tracheal intubation using a fiberoptic bron­ choscope. Can ] Anesth. 1 998;45 :496.

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Ai rway Tec h n i q ues 1 8 . Mort T C . Tracheal tube exchange: feasibility of continuous glottic view­ ing with advanced laryngoscopy assistance. Anesth Ana/g. 2009; 1 0 8 : 1 228- 1 23 1 . 1 9. Mehta N , Valesky WW, Guy A, Sinert R. Systematic review: i s real-time ultrasonic-guided central line placement by ED physicians more suc­ cessful than the traditional landmark approach? Emerg Med ]. 20 1 3;30: 3 5 5-359.

7.2. For the same patient, and in the absence of hypoxemia (with Sa0 > 95%), which of the following is a reasonable 2 intubating technique? A. direct laryngoscopy using a Macintosh blade B. tracheal intubation using the intubating LMA (Fastrach'M) C. retrograde intubation

SELF-EVALUATION QU ESTIO N S 7. 1 . A stridorous, mentally challenged patient was brought to the operating room for an urgent neck exploration because of a neck hematoma following a neck dissection 2 days prior. In the presence of hypoxemia with Sa0 less 2 than 80%, which of the following is a reasonable airway management option? A. bag-mask-ventilation

D. intubation using a lightwand (Trachlight'M) E. digital intubation 7 . 3 . For the same patient, in the presence of severe hypoxemia with Sa0 less than 70%, while setting up for a cricothy­ 2 rotomy, which of the following is a reasonable intubating technique? A. direct laryngoscopy using a Macintosh blade

B. the use of an extraglottic device

B. tracheal intubation (Fastrach 'M)

using the

intubating LMA

C. tracheal intubation using a Macintosh laryngoscope

C. intubation using a lightwand (Trachlight'")

D. surgical airway

D. intubation using a Glidescope®

E. all of the above

E. all of the above

1 43

C H A PT E R 8

Bag -Mas k-Ventilation George Kovacs, Michael F. Murphy, and Nicholas Sowers

I NTRO D U CTION . . . . . . . . .

1 43

BAS I C P R I N C I PLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1 45

TECH N I Q U E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 48 COM P LICATI ONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1 51

S U M MARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1 52

SELF-EVALUATIO N Q U ESTI O N S . . . . . . . . . . . . . . . . . . . 1 54

I NTRODUCTION Providing effective ventilation and oxygenation using a bag mask is probably the single most important component of air­ way management. Bag-mask-ventilation (BMV) refers to the use of a bag-mask unit, most of which but not all have valves (in which case they are referred to as Bag-Valve-Mask units or BVMs) system/device to deliver gas rich in oxygen either pas­ sively or actively by manually ventilating the patient using a face-mask interface. Examples of non-valved bag-mask devices include Mapleson E (Jackson Rees Modification of Ayres T-piece) and other t-piece occlude systems. Manual noninvasive ventilation also accurately describes the use of a BMV device to provide positive pressure ventilation (PPV) . This should be differentiated from mechanical noninvasive ventilation, which also uses a face-mask interface but provides respiratory effort assistance (PPV) delivered by specialized ventilator. • Is There Sti l l a Role for Bag-Mask-Ventilation

in Th is Advanced World of Difficult Airway Devices?

Definitive airway management has traditionally been defined as the secure placement of an endotracheal tube (ETT) in the

trachea. Although few would argue that there has been a philo­ sophical and evidence-based shift away from defining airway management by the method of gas exchange to focus on the goals of resuscitation namely, maintaining patient's oxygen­ ation and ventilation while preserving hemodynamic status. In other words, ETTs don't save lives, whereas providing adequate perfusion and gas exchange does. Optimal oxygenation and ventilation may be provided using ETTs, extraglottic devices (EGOs) , BMV devices, and surgical methods. Which method is most appropriately employed will depend on patient charac­ teristics, the clinical situation, and practitioner's skill. Bag-mask-ventilation particularly in the pre-hospital setting has been shown to be no less effective than endotracheal intu­ bation (ETI) or EGO use. 1-4 In a large prospective population­ based study of out-of-hospital cardiac arrest (OHCA) patients (649,654) , survivors who received BMV had more favorable neurologic outcomes compared to those who had their airway managed by ETI or EGD.5 With increasing controversy regard­ ing the value of pre-hospital ETI, other means of maintaining oxygenation and ventilation including BMV are being reaf­ firmed as an airway management priority.6-1 2 For OHCA, ventilation has been de-emphasized in the early phase of adult non-asphyxia-related resuscitation where oxygen delivery is more dependent on blood flow than on arterial oxygen content. There is consensus that advanced airway management should not be considered a priority over high-quality chest com­ pressions as preformed in cardioplumonary resuscitation (CPR) and defibrillation and has the potential of causing harm by interrupting CPR, from complications of airway management, impairing cerebral perfusion (EGOs) , and perhaps inadvertent hyperventilation. l , l l While there i s a theoretical advantage in using EGOs in the context of cardiac arrest where chest com­ pressions can continue uninterrupted, prospective data to sup­ port the preferred approach for pre-hospital airway management in OHCA is lacking and awaits further study (AIRWAYS-2 & PART) . While the focus of current studies is determining which advanced airway best serves this patient population, large

1 44

Ai rway Tec h n i q ues

retrospective data sets suggest the need to prospectively com­ pare less invasive techniques of oxygen delivery such as BMV and passive oxygen insuffiation to more active invasive airway procedures (ETI, EGD) . 1 3-15 For non-OHCA patients advanced airway management has not consistently shown to be of benefit when compared to a basic approach that includes BMV3 ,4·16 Many believe that pre­ hospital airway management outcomes are less related to the device and more to do with the decisions and skills with which these airway devices are employed. 10• 1 1 Worsening hypox­ emia and inadvertent hyperventilation occurring during and post advanced airway management placement are thought to be major contributors to the observed poor outcomes in the pre-hospital setting. 17 The technical imperative of succeeding in placement of an advanced airway device may be distracting clinicians away from the homeostatic goal of improving and maintaining oxygen and ventilation status. This goal may often be best achieved with BMV Most of the existing data comes from North American ground-based ambulance services. Bag-mask-ventilation can be a challenging skill to learn and perform effectively. 18-20 Despite the advent of numerous alternative devices, j ust as direct laryngoscopy (DL) remains the current gold standard for ETT placement, BMV still remains the primary method of providing initial basic life sup­ port (BLS) oxygenation and ventilation in most resuscitation settings. 2 1 Although this may change, there currently is no compelling evidence of superiority of advanced airway tech­ niques over BMV 1 3' 22-27 Compared to BMV used by relatively inexperienced health care providers, laryngeal mask airways (LMAs) have been reported to be rapidly placed, "easy to use" and effective as ventilation device. 2 8 Similar results have been shown with the laryngeal tube. 2 5 Other reports of EGO "field use" have, however, demonstrated lower than expected success rates and worse outcomes when compared to BMV despite self­ reported ease of use.13' 23'29'30 In contrast, there is some evidence that for the neonatal population, EGO use is more effective than BMV during resuscitation efforts.31 Success and complications of any airway device are more often related to training and experience than the device itself. Despite its effectiveness in skilled hands, BMV is facing a grow­ ing competition from EGOs that even in unskilled hands, are relatively easy to teach, learn, and ultimately deliver as a pri­ mary method for oxygenation and ventilation. • What Are the Key Components

of a Bag-Mask System?

Also referred to as manual resuscitators, these devices usually employ a bag and an integrated one-way valve connected to an ETT, an EGO, or a mask to manually provide PPV Despite there being various rypes of BMV systems, for most part they share common features (Figure 8-1) :3 2 •

•

Universal connector: with a 22-mm outside diameter (00) , which fits standard face-masks, and a 1 5-mm internal diameter (ID) that connects to standard ETTs, EGOs, and cricothyrotomy or tracheotomy cannulae. Non-rebreathing patient valve: to prevent rebreathing while allowing exhalation.

Non-rebreathing valve

�� �

Tra nsparent mask

1 00% 0 2

02 > 1 L/m i n

F I G U R E 8-1 . B a g - m a s k schematic (Repro d u ced w i t h perm ission fro m Safa r P, B i rc h e r N G . Ca rd i o p u l m o n a ry Cerebra l Resu scitation, 3 rd e. P h i l a d e l p h ia, PA: S a u n d e rs; 1 988.)

•

•

•

•

•

•

•

Self-inflating bag: supplied in adult ( 1 600 mL) ; child (500 mL) ; and infant (240 mL) sizes that when manually compressed deliver a corresponding tidal volume; or an oxy­ gen reservoir bag that is inflated by receiving high oxygen flow through an adjacent connector. Oxygen inlet valve: providing unidirectional flow from the oxygen reservoir to the self-inflating bag. Air intake valve (at reservoir end) : a safety valve intended to allow entrainment of room air if supplied oxygen source is disconnected. Safety outlet valve (at reservoir end) : a flow-limiting valve Other features of BMV systems may include: positive pres­ sure relief or "pop-off' valves with the intent of limiting airway pressures to avoid barotrauma when the manual resus­ citator is connected to an ETT. An expiratory port at the patient connector that allows attachment of a PEEP valve. Flow-limiting valve located at the patient end of the self­ inflating bag designed to limit inspiratory flow decreasing the risk of both hyperventilation and excessive airway pressures (Smart Bag-+ ) .

Th e face masks used i n conjunction with the manual resuscitator vary in material, size, seal type, and transparency. Traditionally, black/opaque rubber masks with an anatomically contoured seal were used in the operating room setting con­ nected to an anesthetic circuit. These have been replaced to a large extent in most environments by transparent silicone, or plastic latex-free non-disposable and single-use masks that provide the added benefit of being able to visualize the mouth/ nose-mask interface and therefore react to the presence of vomi­ tus and other secretions. Rather than anatomically conform­ ing to the patients face, the seals in these disposable masks are either made of foam or an air-filled "cushion" that molds to the underlying facial anatomy. While the unidirectional valves are similar amongst avail­ able BMV devices, it is important to appreciate whether the device has a dedicated expiratory valve. This valve provides an unidirectional flow for expired gases and will not allow room air entrainment for the spontaneously breathing patient. If there is an open expiratory port, it usually means there is no dedicated

Bag-Mask-Venti l ation

intrinsic expiratory valve and in the spontaneously breathing patient they may entrain room air.33 This is easily dealt with by adding a PEEP valve.

BASI C PRINCI PLES • How Do You Accu rately Anticipate

Difficult Mask-Ventilation?

Perhaps the simple answer is you can never ensure 1 00% accuracy when you are trying to predict anything.34 The safest approach is perhaps to "always anticipate the unexpected." In the anticipated difficult airway, proceeding depends on con­ text. In an elective operating room setting, predicted difficulty will often mean a very different course (including canceling the case) than in an emergency situation in which a choice of not proceeding is usually not an option. In trying to anticipate dif­ ficulty, the core two traditional questions that all practitioners should ask themselves prior to proceeding are: •

Will I be able to maintain oxygenation and ventilation by BMV if intubation attempts fail? If not, will I be able to oxygenate and ventilate rapidly using a rescue device or tech­ nique, such as an EGD or surgical airway?

Early literature on predicting the difficult airway focused on laryngoscopy and intubation.35-37 Recognizing that main­ tenance of oxygenation and ventilation is the priority in air­ way management and that this is often best achieved rapidly and early by BMV, the identification of predictors of difficult mask-ventilation (DMV) has also been a focus of research.38-43 Most airway management decision algorithms require a "for­ mal" patient assessment focused on identifying predictors of difficulty. This assessment is a major contributor in deciding whether neuromuscular blockade can safely be used to facilitate intubation. While it is important to assess all aspects of the difficult airway, BMV has been considered the most important as this intervention is usually the primary "go to" technique when tracheal intubation attempts to fail. More recently, how­ ever, some guidelines suggest either BMV or an EGD follow­ ing failed tracheal intubation or moving to an EGD instead of BMV at this stage.44,45 At this point, oxygen desaturation has often already begun and clinical deterioration often fol­ lows rapidly. Despite there being numerous alternative rescue options available to the practitioner, BMV is universally avail­ able, familiar to most, and very effective. Earlier data estimated that "cannot intubate/cannot oxy­ genate" clinical situations occurred at a rate between 0 . 0 1 and 2 in 1 0,000 general anesthetic cases.46 More recent data have reported the incidence of DMV in the operating room setting has varied from a low of 0 . 9 % to a high of 7.8%.39-42,47,48 This reported variation likely relates to differences in case definition, outcome criteria, and sample size. A large multi-center study of over 1 76,000 patients reported and incidence of DMV if 2.5% with an incidence of DMV with concurrent difficult intuba­ tion of 0.4%? In a previous study of over 50,000 patients, "impossible" BMV defined as an inability to establish BMV using two-hand technique and "multiple airway adjuvants" , occurred in 0. 1 5% of the study population. 39

Langeron et al.42 prospectively evaluated 1 502 patients requiring routine general anesthesia to determine both the incidence and factors associated with DMV The reported inci­ dence of DMV in this population was 5%. Five independent factors associated with DMV were identified: presence of a beard; age older than 5 5 ; body mass index (BMI) > 26 kg·m- 2 ; lack of teeth; and a history of snoring. The presence of two of these factors in a patient was 72% sensitive and 73% specific for DMV42 Other studies involving large patient populations have validated the above findings and identified additional risk factors, including male gender, a history of neck radiation, high Mallampati grade (Grade III or IV) , increased BMI ( > 30 kg·m- 2) , and limited jaw protrusion (Table 8-1) .38-41 In Kheterpal et al.38 study of patients with difficulty for both BMV and DL, Mallampati grade (III or IV) , neck radiation or mass, male gender, limited thyromental distance, presence of teeth, and BMI > 30 kg·m- 2 were among the more significant risk factors (odds ratio [OR] > 2) . In the study by Kheterpal et al. 39 the presence of three or more predictors (neck radiation, male, OSA, Mallampati III or IV, beard) significantly increased the risk of impossible mask­ ventilation (IMV) with an OR of 8.9 compared to patients without these risk factors. Another important finding from this study is that of the IMV group, 25% were also difficult to intu­ bate. In a more recent follow-up study examining combined dif­ ficult BMV and difficult laryngoscopy, the odds of encountering difficulty increased significantly with the number of risks iden­ tified. However, these retrospective data are difficult to apply prospectively. While many airway practitioners may accept inad­ equacies in terms of positive predictive value, it would be unwise to apply these findings as a negative predictive tool. These recent reports differentiating DMV from IMV recog­ nize the fact that clinically BMV challenges are part of a contin­ uum from easy to impossible.47 A numeric representation this DMV continuum has been proposed; however, it has not been consistently used or accepted to date in the literature.49 The dif­ ference between DMV and IMV is simply that DMV is usually correctable (i.e. , two-hand and two-person technique) , whereas IMV represents a failure and the need to abandon BMV in favor of another intervention (DL, or video-laryngoscopy [VL] if not attempted, EGD, or a surgical airway) . Another impor­ tant observation that has caused some degree of controversy is the value of "checking" for BMV difficulty prior to administer­ ing a neuromuscular blocking agent. Current evidence seem to support the use of muscle relaxants to facilitate both BMV and laryngoscopy.48'50-5 2 It is important to appreciate the fact that these studies did not examine the incidence of DMV in patients requiring emer­ gency airway management. Levitan et al.53 examined the abil­ ity to assess for predictors of the difficult airway in emergency department patients requiring intubation and found that only 32% of this population would have been able to be assessed adequately for difficulty because of limitations such as an inability to follow commands or being immobilized for cervical spine (C-spine) precautions. The incidence of DMV is not known in this population, However, emergency cricothyrotomy outside of the OR (as a

1 45

1 46

Ai rway Tec h n i q ues

TAB L E 8-1 .

Stu d i es Reporti n g I n d ependent Pred ictors of Difficult BMV

I nvestigators

Design

Population

DMV I n cidence

Risk Factors

Comments

La n g e ron et a l . 2000

Prospective observat i o n a l

5%

Yi l d iz et a l . 2004

Prospective observati o n a l

1 5 02, a d u lt ro uti n e GN patie nts 5 76, a d u lt ro uti n e GA

Fi rst study eva l uati n g i n d e pe n d e n t risk fa ctors S m a l l sa m p l e size,

Kheterpa l et a l . 2006

Prospective observati o n a l

22,660, adult GA

Kheterpa l e t a l . 2009

Prospective obse rvat i o n a l

53,04 1 , a d u lt GA

2 .2%, 0. 1 5 % I MVb

Kheterpa l et a l 20 1 3

Prospective observati o n a l

1 76,679, adult GA

2.5%, 04% both DMV a n d DDL

Ag e > 5 5 , BM I > 26 kg · m - 2 , bea rd, edentu l o u s, snoring M a l e, M a l l a m pati IV, i n c rea s i n g a g e, s n o r i n g , i n c rea s i n g we i g ht B M I > 30 kg · m - 2 , bea rd, M a l l a m a pati I l l IV, a g e > 5 7, l J Pc, s n o r i n g I MV: neck ra d iation, m a l e, OSAd, M a l l a m pati I l l IV, bea rd Co m b i ned DMV!DDL: M a l l a m a pati I l l IV, Neck pat h o l ogy/ra d s, M a l e, Li m ited thyromenta l d i sta n ce, p resence of teeth B M I > 30 kg · m - 2

7.8%, 1 5 .5% of d iffi c u l t i ntu bations 1 4%

D iverse c l i n i c i a n g ro u p Od d s ratio (OR) 8.9 vs. no r i s k fa ctors ( R F) OR i n c reases with # R F 4 RF:OR 2 . 5 6 5 RF:OR 4. 1 8 6 RF:OR 9.23 7-1 1 RF:OR 1 84

A b b reviat i o n : D D L, Diffi c u l t d i rect l a ryn g oscopy a G e n e ra l a n esthesia bl m poss i b l e BMV cJ aw p rotru s i o n dObstru ctive s l e e p a p nea

TAB L E 8-2. DMV Path o p hysiology a n d Res ponse

DMV Pred ictor

Pathophysiology

Response

Obes ity

R a p i d d esatu ration, l com p l i a n ce, j u p per a i rway soft tissues S n o r i n g : j u p per a i rway co l l a pse S o u n d s : st r i d o r, w h eezi n g j res i sta nce l tissue e l a stic ity, l jaw and neck m o b i l ity, i edentu l o u s rate M a s k sea l M a s k size, fit Non-co m p l ia nt d i storted tissues Excess soft tissues, u p per a i rway co l l a pse ? a ssoci ated comorbid ities l a b i l ity to m a n a g e to n g u e, u p pe r a i rway col l a pse As per a bove, seco n d a ry i nj u ry fro m d iffi c u l t l a ryng oscopy

Position i n g : sitt i n g d e n itrog enation, ra m p

S n o r i n g , (a i rway so u n d s) Age Bea rd Ed entu l o u s Neck rad i ation M a l l a m pati I l l o r IV Male Di m i n i s h ed Jaw p rot r u s i o n Diffi c u l t i ntu bati o n

marker for cannot intubate, cannot oxygenate) rates have fallen to between 0. 1 o/o and .5 o/o, and may underrepresent the inci­ dence DMV and are still much higher than that reported in the controlled operating room setting. 5 4- 5 7 Table 8-2 summa­ rizes the likely pathophysiology behind the various predictors of DMV

O PA 2-h a n d BMV, j exp i ratory t i m e Leave d e n t u res i n p l a ce A p p l y o i ntment Leave d e n t u res i n , OPA O PA, 2-h a n d BMV, early EGD O PA 2-h a n d BMV O PA, 2-h a n d BMV, early EGD

• What Anatomic Factors Need to

be Considered in Providing Safe and Effective BMV?

The primary goal of BMV is to facilitate oxygenation and ven­ tilation by providing an unimpeded transfer of gas (oxygen/ carbon dioxide) to and from the lungs. In the unconscious or

Bag-Mask-Venti l ation

anesthetized patient with normal anatomy, it has been tradi­ tionally thought that obstruction to the easy to-and-fro move­ ment of gas with BMV was primarily related to the effect of a "relaxed" tongue falling back against the posterior pharyngeal wall. Data gathered during fluoroscopy in studies of obstructive sleep apnea (OSA) patients have improved our understanding of the pathophysiology of upper airway dynamics in the sleep­ ing patient. In addition to obstruction caused by the tongue, there is also a loss of velopharyngeal and hypopharyngeal muscle tone.58·59 This results in soft tissue collapse leading to the posterior displacement of both the soft palate and epiglot­ tis to oppose the posterior pharyngeal wall and contribute to obstruction (velopharyngeal and hypopharyngeal collapse) .58 The hypopharyngeal site of obstruction is clinically supported by the observation that placement of an OPA without perform­ ing an adequate jaw thrust may not alleviate obstruction caused by "normal" upper airway soft tissues. When a patient is placed in the "sniffing" position, there is flexion in the cervico-thoracic region with extension occipto­ cervical region. This position has been traditionally thought to facilitate "alignment" of the axes necessary to visualize the glottic inlet during DL. Although there has been some question as to whether this position provides any advantage over simple head extension, data do support the combination of neck flexion with head elevation in enabling glottic exposure during laryngos­ copy.60·61 It is less clear, however, if this position improves upper airway patency for BMV. There is some evidence that the retro­ palatal and retroglossal region is enlarged by placing anesthetized non-obese patients with OSA in the sniffing position and mask­ ventilation may be improved.62'63 Collectively these pharyngeal dilator muscles lose their tone with anesthesia thereby increasing the pharyngeal closing pressure. Pharyngeal patency is improved most significantly by maintaining a sitting position coupled with mandibular advancement, and less so head and neck positioning.64 In addition, it is well known that obese patients desaturate early, a clinical phenomenon that can be delayed by denitrogenating in the sitting (as opposed to supine) position.65 At this point, it is reasonable to state that head and neck reposi­ tioning from neutral to a position that involves a degree of neck flexion with head elevation may improve BMV and is appropri­ ate in anticipation to perform DL should it become necessary. While head and neck positioning may be considered of vital importance for DL, the key anatomic manipulation that facili­ tates BMV is performing a jaw thrust.66 The genioglossus mus­ cle is attached to the mandible and the hyoepiglottic ligament attaches the tongue to the epiglottis. Therefore, translating the mandible anteriorly pulls the tongue and in turn the epiglot­ tis anteriorly and opens the airway. This maneuver originally described over a century ago (Esmarch-Heiberg's maneuver) has been demonstrated to be superior to "chin lift" and "head tilt" when performed alone, during observations made of anes­ thetized patients undergoing (pre-procedure) head and neck fluoroscopy.67·68 Recognizing that obstruction in the uncon­ scious patient is related to more than the tongue falling poste­ riorly, the "triple airway" maneuver (open mouth, head tilt, jaw thrust) was suggested to be th e b est approach . 69,7 o More recent evidence supports the jaw thrust alone as being equally effective to the triple airway maneuver in relieving obstruction.68

• What Is the Role of BMV in Difficult

Ai rway Algorithms?

Numerous algorithms have been published to guide prac­ titioners in the management of the difficult airway (see Chapter 2) .44.45·71·72 Most of these guidelines or recommenda­ tions are generated using available evidence and expert opinion from specialized "working groups" and/or anesthesiology soci­ eties. Historically algorithms have had limitations for being too complicated or impractical for application in emergency situa­ tions outside of the operating room, where it is not possible to "cancel" the case or "awaken" the patient. A difficult airway may be any or all of difficult BMV, difficult laryngoscopy, difficult intubation, difficult EGD use, or diffi­ cult surgical airway placement. Most algorithms or approaches separate the anticipated from the unanticipated (or encountered) difficult airway. In the former scenario, predicted difficulty leads a defined, usually more controlled path, whereas in the latter, whether predicted or not, "real-time" difficulty is being experienced and demands an immediate and specific course of action, depending on the type of difficulty encountered. In approaching the difficult airway, the ability to success­ fully perform BMV is a critical management j unction in most, if not all algorithms. The most prominent place for BMV as part of any difficult airway algorithm is between failed intuba­ tion attempts. However, it is important to appreciate the role of BMV even before a first attempt at laryngoscopy and intuba­ tion. Assuming the patient can generate sufficient tidal volumes with an adequate respiratory rate, the bag portion of the BMV device does not have to be squeezed to deliver close to 1 00% oxygen. It is not uncommon (and in some situations is poten­ tially hazardous) that when switching from a non-rebreathing mask (or another mask type) to BMV, positive pressure is often instinctively applied. If assisted BMV is applied without syn­ chrony, gastric insuffiation is much more likely to occur. In the pre-intubation phase of airway management, the use of a BMV device to denitrogenate should be encouraged. This approach offers several advantages: •

•

•

•

Passive delivery of high concentration of oxygen (approaching 1 00%) Opportunity to size the mask properly Provides "hands-on feel" for predicting DMV Provides opportunity to improve gas exchange with assisted BMV

Various methods of denitrogenation have been suggested in an attempt to minimize desaturation during laryngoscopy and intubation. This is relatively easy to accomplish in healthy adults with normal pulmonary mechanics and oxygen con­ sumption rates. It should be recognized that flow from the oxy­ gen source will decay by as much as 50% through most BVM devices. While this is not an issue at normal minute ventila­ tions, it can result in dilution of Fi02 by room air entrainment, leaks around the mask, and an open expiratory port in BVMs without a dedicated expiratory valve.33'73 In the physiologically normal patient (normal lungs, respiratory rate, and tidal vol­ umes) , the key to denitrogenation is having a closed delivery system (i.e., a bag-mask unit with an expiratory valve) attached . . . 74,75 to h igh flow oxygen cwr a mm1mum o f 3 mmutes.

1 47

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Ai rway Tec h n i q ues

In patients with shunt physiology, effective denitrogenation can be improved through the addition of PEEP valve in the spontaneously breathing patient. 76 With the addition of a second high flow oxygen source applied through nasal prongs (HFNO) under a well-fitted mask, the BVM/PEEP and HFNO combina­ tion will provide CPAP and through alveolar recruitment may provide for improved denitrogenation?6 While the addition of manual assisted ventilation synchronized with the patient's inspiration (PPV) may provide only marginal denitrogenation benefit, the addition of a PEEP valve to this sequence in an attempt to replicate ventilator delivered BiPAP may be of value for denitrogenation in certain patient populations?7 Ventilation during the apneic patient as part of a rapid sequence induction has been somewhat controversial. This teaching, however, was based more on theory than science. In fact, Sellick's78 original paper stated that manual PPV in com­ bination with cricoid pressure could be done without gastric distention risk. Data have since supported active denitrogena­ tion using a manual resuscitator with or without the applica­ tion of cricoid pressure as long as "good" technique is used avoiding high airway pressures.79-81 BMV is in fact clinically indicated during Rapid Sequence Intubation (RSI) in certain patients (obese, hypoxemic, pediatric) who may have low base­ line oxygen saturation, high oxygen consumption rates, and/or low functional residual capacity.77'8 2'83 Finally, the knowledge of adequate BMV soon after the drugs are given is reassuring, particularly in situations where difficult intubation may be encountered, and represents a common practice.8 2

TECH N I Q U E • What Defines Optimal BMV Technique

and How do You Assess the Adequacy of Ventilation?

There are three important components to proper BMV tech­ nique: mask seal, airway opening, and ventilation. M a s k Seal

An appropriately sized face mask is attached to the bag-mask device and applied to the patient's face. The lower border of the mask's cuff is first applied to the groove between the lower lip and the chin, then the mask can be placed down across the nasal bridge. The thumb and index finger of the airway practitioner's hand apply sufficient pressure on the face mask to achieve a good seal (Figure 8-2) . Note, however, that sealing pressure must be achieved without excessive downward pres­ sure on the patient's mandible, as this may worsen functional obstruction-rather, the mandible is lifted to meet the mask. Small adjustments to the position of the mask on the patient's face (e.g. , with small movements to left or right) are made as needed to achieve a seal. Ai rway O pe n i n g

When employing a one-person technique, the ring and long fingers of the nondominant hand grasp the bony ridge of the patient's mandible, and, if practical, the fifth finger hooks under the angle of the mandible to provide a jaw thrust (Figure 8-2) .

F I G U R E 8-2. Proper bag-mask-venti l ation tec h n i q ue: A g ood m a s k sea l i nvolves a p p l y i n g sufficient pre s s u re o n the face m a s k b y the t h u m b a n d i n d ex fi n g e r o f the practitioner's h a n d . T h e r i n g a n d l o n g fi n g e rs o f the n o n d o m i n a n t h a n d g ra s p the b o n y r i d g e o f the patient's m a n d i b l e, a n d , if practica l, the fifth fi n g e r hooks u n der the a n g l e of the m a n d i b l e to provide a jaw thrust.

In the event the airway practitioner has a small hand, the long finger is hooked under the mentum to provide a jaw pull. These three digits provide counter-pressure to the digits applying the mask to the face, but also apply an upward lift to the man­ dible to help perform an airway opening jaw thrust. Note that these three fingers should not be placed directly under the patient's chin unless lifting it forward, as midline pressure under the chin can contribute to airway obstruction. This latter directive is particularly important in small children and infants. Concomitantly, the entire hand also attempts to keep the head extended (if no C-spine precautions) . Ve nti lation

The practitioner's dominant hand is free to gently squeeze the bag. Volumes should be delivered with attention to the inflat­ ing pressure as well as the patient's status: if apneic, the patient should be carefully ventilated (attached to high flow oxygen) at a rate of 1 0 to 1 2 breaths per minute, at a tidal volume of 6 mLkg- 1 , or 500 to 600 mL in the average adult. 1 Smaller tidal volumes (e.g. , 3-400 mL in the adult) at increased rates ( 1 5- 1 8 breaths per minute) may lead to less gastric insufflation. Although adult ( 1 . 6 liter) manual resuscitators may deliver

Bag-Mask-Venti l ation

varied volumes, excessive and rapid compression of the bag must be avoided. The goal, as stated previously, is to produce visible chest rise. In the patient still demonstrating respiratory effort, assisted BMV should be performed, synchronizing the positive pressure breath to the patient's inspiratory effort. If the patient is tachypneic, it will be appropriate to simply deliver an assisted ventilation with every third or fourth breath. • How to Respond to Difficult

BMV Situations?

With optimal technique, significant difficulty with BMV is rarely encountered in the absence of airway pathology.39•48 In the acute setting, BMV is often delegated to another health care practitioner while the practitioner prepares for definitive airway management. While this may be appropriate, it is important to accept that BMV is a difficult skill for those who perform it infrequently and vigilance rather than inattention is recom­ mended. Abandoning BMV in the uncommon scenario of fail­ ing BMV should only occur after the most experienced "set of hands" has failed. Difficult BMV (DMV) is often defined as the inability to maintain an acceptable oxygen saturation despite using "good technique." However, it is the "dynamic" inability to maintain oxygen saturation that is important. Failure to maintain accept­ able oxygen saturations or falling saturations demands a change in approach. Although one response to a DMV situation is to proceed to intubation, DMV may itself predict difficulty with laryngoscopy and/or intubation.39 .4?.4 S Good BMV skills and an approach to DMV are crucial skills in ensuring oxygenation of a patient prior to, or between laryngoscopy attempts. In the setting of a failed airway in which one is not able to maintain acceptable oxygen saturations, immediate preparation for a cricothyrotomy is mandatory while one simultaneously attempts "better" BMV Response to DMV requires a staged response that may include the following: •

•

•

•

•

•

•

•

•

Reposition the head by performing an exaggerated head tilt/chin lift (if not contraindicated) ; Open the mouth permit anterior translation of the mandible and tongue in concert with an aggressive jaw thrust; Insert an appropriate size oropharyngeal airway (OPA; see Figure 8-3) and as many as two nasopharyngeal airways (NPAs) ; Perform two-person mask ventilation technique; If cricoid pressure is being applied, ease up on, or release it; Consider a mask change (size or type) if seal is an issue; Rule out foreign body in the airway; Consider a "rescue" ventilation device, for example, an EGO, such as a LMA; Consider an early attempt at intubation.

Steps A, B, and C, as listed above, should occur almost simultaneously and very early in the DMV situation. DMV is often due simply to the failure to adequately open a func­ tionally obstructed airway. Attempted ventilation against this obstruction results in a leak at the mask/face interface, often resulting in the practitioner's attempting to remedy the prob­ lem by pushing down harder on the mask to attain a seal, though this can aggravate an already obstructed airway. Rather,

F I G U R E 8-3. I n sertion of a n a ppro p riate s ize o ro p h a ryngeal a i r­ way is necessary to a l l eviate a i rway obstruction.

F I G U R E 8-4. Two-h a n d a n d two-person bag-mask-ventilation.

what must occur is a more pronounced jaw lift or thrust, with resultant airway opening occurring as anterior movement of the mandible elevates the tongue, epiglottis, and soft palate away from the posterior pharyngeal wall. This is best performed with the aid of a second person. Two-person mask-ventilation is easy to perform and is often much more effective than one person BMV84·85 As shown in Figure 8-4, the two-person technique can be performed in a number of ways; however, the "thumbs forward thenar eminence" (T-E) grip appears to be more effec­ tive than the traditional C-E grip (place the thumb and first finger around the top of the mask, forming a "C," while using the 3rd, 4th, and 5th fingers, forming an "E," to lift the angles of the jaw) .86'89 Oropharyngeal airways help alleviate functional airway obstruction caused by relaxation of the tongue against the soft palate and to a lesser extent the posterior pharyngeal wall. They are most often used as an adjunct to BMV of an obtunded or unconscious patient. Made of plastic, the component parts are a curved hollow lumen (in the Guedel version) or side gutters

1 49

1 50

Ai rway Tec h n i q ues

F I G U R E 8-5. Different s izes of Guedel o ro p h a ryngeal a i rways.

F I G U R E 8-6. Different s izes of n a s o p h a ryngeal a i rways.

(the Berman version) (Figure 8-5) , both with a proximal flange which abuts the patient's lips, and a proximal bite block which may also be used as a color-coded size indicator. Oropharyngeal airways are sized by length in centimeters, and are available in sizes for all ages. Choosing the appropriate size is important, as an OPA that is too long may precipitate laryngospasm or create obstruction; and if too small it may be ineffective. Although never formally validated, many airway practitioners approximate correct OPA length by placing it alongside the patient's cheek66: from the corner of the mouth, the tip of the OPA should reach the angle of the mandible or the tragus of the ear (Figure 8-3) . A typical adult female will take an 8-cm OPA, and an adult male, 9 or 1 0 em. The OPA should be inserted inverted, (i.e., with its concave surface directed cephalad) and advanced until the distal tip will proceed no further in this inverted position. At that point, the OPA is rotated 1 80 degrees, so that the concavity faces caudad. Advancement continues around the curve of the tongue until fully inserted. Inverted insertion helps avoiding aggravating obstruction due to posterior tongue displacement into the hypo­ pharynx during OPA placement. Alternatively, it can be inserted non-inverted with a tongue depressor to manage the tongue: this is the preferred technique in infants and younger children to help avoid trauma to delicate tissues. OPAs are not well tolerated in the awake or semiconscious patient with intact airway reflexes, where insertion may stimu­ late gagging, laryngospasm, or vomiting and aspiration. In addition, care must be taken to rule out a foreign body in the oropharynx prior to OPA insertion. A nasopharyngeal airway (NPA) may be a useful option where trismus precludes OPA insertion (e.g. , hypothermia, severe head injury) , and may be better tolerated than an OPA in the awake or semiconscious patient with intact airway reflexes. While effective at alleviating functional airway obstruction, disadvantages of the NPA include transient patient discomfort during insertion and the potential to incite epistaxis. While application of a vasoconstrictor (e.g., xylometazoline) can min­ imize the risk of epistatxis, this may not be practical when a

NPA is urgently needed. NPAs, also known as "nasal trumpets," are made from soft material, for example, latex or silicon, have a hollow interior, beveled leading edge, and a proximal flange to abut the patient's nostril (Figure 8-6) . Adult NPAs are generally sized by their 10 i n mm. Typical adult sizes for small, medium, and large NPAs are 6, 7, and 8 mm 10, respectively. One commonly used (but nonvalidated) sizing method is to use an NPA of a length corresponding to the distance from nose tip to the tragus of the ear. Sizing based on patient height makes more anatomic sense, resulting in a recommendation for a 6-mm 10 NPA for an average adult female and 7 mm for an average male. The NPA is lubricated and advanced into the patient's nos­ tril, perpendicular to the face, resulting in passage along the floor of the major nasal airway. Authorities vary in their recom­ mendation whether the bevel of the NPA should face toward or away from the nasal septum. A slight twisting motion can be used during insertion. If significant resistance is encoun­ tered, insertion should be attempted through the other nos­ tril. Insertion continues until the flange of the NPA abuts the nasal ala. NPA use is relatively contraindicated in known bleeding diathesis, including heparinized, anticoagulated, or recently thrombolyzed patients, and in suspected cribriform plate frac­ tures. In the head-injured patient, common sense dictates bal­ ancing the substantial risk of hypoxemia with the benefits of producing a patent NPA in the event an oral airway is ineffec­ tive or impossible. Cricoid pressure can cause difficulty with both BMV and laryngoscopy as previously discussed. Excessive cricoid pressure (as may be applied during an RSI) may distort the airway and result in a partial or complete obstruction. If significant dif­ ficulty with BMV is encountered during application of cricoid pressure, the assistant should momentarily ease (initially by 50%) or release the applied pressure. It may become apparent once BMV is underway that the chosen mask size is incorrect. This is often the case where initial sizing occurred with a patient's dentures in place. Especially

Bag-Mask-Venti l ation

with encountered difficulty, the improved seal allowed by an appropriately sized mask makes the change worthwhile. The decision to move to a rescue EGD, such as a laryngeal mask airway (LMA) or laryngeal tube (King LT) , will depend on the patient's clinical status and whether DL has yet been attempted. If there has been no initial attempt at DL, it may be appropriate to proceed to an intubation attempt. If, on the other hand, DMV is encountered in the setting of an already failed attempted at intubation, placement of a rescue ventila­ tion device, such as an LMA, should be considered. DL is also the method of choice to rule out obstructing lesions, including foreign bodies and lingual tonsillar hypertrophy. • Is Cricoid Pressu re Appropriate to

Use With BMV?

Aspiration incidence rises with the number of attempts at intu­ bation to a high of 22% in the emergency setting.90 Mortality from aspiration has fallen but still remains relatively high. Does the application of cricoid pressure prevent regurgitation and more importantly does it reduce morbidity and mortality? Since Sellick's78 description in 1 9 6 1 , cricoid pressure has been recommended as a safe and necessary airway maneuver meant to reduce the risk of aspiration during airway management. However, based on accumulating evidence, this "standard" has been questioned.81.91-94 In addition, there is reasonable evidence for potential negative effects of cricoid pressure administered during BMV that include reduced tidal volumes, increased peak inspiratory pressure, and difficult ventilation. Given that there is little evidence to support the widespread use of cri­ coid pressure to prevent aspiration and that there is evidence of potential harm in certain situations, many have suggested that the procedure should either be omitted or at least disengaged if a difficult airway is encountered.80·91.92 Anatomically as studied by imaging, the value of cricoid pressure was also being questioned based on observations that the cricoid cartilage moves laterally with compression and causes incomplete luminal esophageal opposition.9 5 -97 More recent literature, however, has documented that with appropri­ ate force applied cricoid pressure, the esophageal entrance is occluded regardless of whether it midline or lateral position.97 The question of whether cricoid pressure reduces morbid­ ity and mortality by preventing aspiration has not, and may not be answered. Aspiration has been documented to occur in cases where cricoid pressure has been applied; however, it has been argued that this could have been from inadequate tech­ nique.94 The clinical risk/benefit debate over the use of cricoid pressure will likely continue. At this point, it can be said that when performed correctly, by occluding the hypopharynx and in preventing gastric inflation during BMV, cricoid pressure may reduce the risk associated with aspiration during airway management. In addition, during BMV, care should be taken to employ good technique by opening the airway, paying attention to inspiratory time, inflation pressure, and delivering appropriate tidal volumes to avoid gastric inflation. If cricoid pressure is being applied, it should be done by an experienced assistant and if BMV becomes difficult, cricoid pressure should be released to assess whether it may be impeding ventilation.

COM P LICATIONS • How to Maximize Gas Exchange While

Minimizing the Risk of Gastric I nflation and Reg urgitation BMV?

With an unprotected airway, the risks of gastric inflation and subsequent aspiration are a real risk during BMV In autopsies of patients having failed resuscitation, the incidence of aspira­ tion has been reported to be 29%.98 Delivering an intended tidal volume and avoiding gastric inflation during BMV depends on various factors, such as lung compliance, airway resistance, and lower esophageal sphincter pressure (LESP) . 99· 100 In healthy adults, the LESP is 20 to 25 em H 0?9·100 2 The risk of gastric inflation is finely balanced with the need to generate sufficient upper airway pressures to achieve ventila­ tion, while maintaining airway pressures low enough to avoid gastric insufflation. Traditionally it has been taught that peak airway pressures below 20 em H 0 would minimize the risk of 2 gastric insufflation. However, Bouvet et al. 101 have shown using ultrasound examination of the stomach of non-obese elective surgical patients that airway pressures of 1 5-cm H 0 caused 2 gastric inflation in 35% of patients. A 1 5-cm H 0 peak air­ 2 way pressure was shown to generate sufficient ventilation. This information led the author's to conclude that airway practitio­ ners performing BMV ought to employ smaller tidal volumes at higher rates to minimize inflation pressures and the risk of gastric insufflation. Recognizing that the risk of aspiration and its related poten­ tial morbidity are related to high airway pressure during BMV, every attempt should be made to provide effective ventilation at minimum peak airway pressures .. Conditions that reduce compliance or increase resistance require higher peak pressures, which would increase the risk of gastric insufflation, and aspira­ tion. Meticulous attention to technique, such as the use of oral or nasal airways, maximum airway opening maneuvers, and reduced tidal volumes, may attenuate this risk. The breathing patient who is receiving "assisted" manual PPV using a BMV device is at particularly high risk. In this situation, the airway practitioner must pay close attention to the timing and delivery of a positive pressure breath at the end of the patient's expira­ tory phase to prevent higher airway pressures more likely to result in gastric inflation. A vicious cycle of "gastric insuffla­ tion" reduced compliance requiring higher airway pressures, that diverts even more gas to the stomach ensues. 100 In extreme circumstances, this can lead to decreased cardiac output from increased intrathoracic pressure and a "can't ventilate" scenario. Previous studies in the pre-hospital setting have documented that stress and an excited state may contribute to "overzeal­ ous" ventilation with large tidal volumes and rapid respiratory rates . 1 1·17·102 The practitioners perceived feedback of inadequate oxygenation and/or ventilation (which is often from inad­ equate relief of upper airway soft tissue obstruction) generates a response of pushing "harder" on the face-mask, while at the same time generating more forceful and frequent ventilations. This response often leads to further gastric insufflation, breath stacking, and the cycle described above. The result is worsening oxygenation and ventilation and a further decrease in cardiac

1 51

1 52

Ai rway Tec h n i q ues

output. The other consequence of increased minute ventilation is the development of respiratory alkalosis, gaining attention recently as a contributor to poor patient outcomes in certain acute care settings . 1 1'103'104 Research related to the delivery of appropriate tidal volumes when using a BMV device has yielded different results depend­ ing on the clinical situation. 105 The American Heart Association recommends the delivery of sufficient tidal volumes to produce a visible chest rise. 1 This recommendation is based on evidence that in an unprotected airway, smaller tidal volumes produc­ ing chest rise (approximately 500 mL) result in less gastric insufflation. Secondly, it is reasoned that during CPR perfu­ sion approximates 30% of normal, meaning that less oxygen is needed and less C0 produced, and lower tidal volumes and 2 respiratory rates are needed. In patients with a sudden dysrhythmic cardiac arrest (e.g., ventricular fibrillation) , hypoxemia and acidosis develop over several minutes. 105 In the very early phases of resuscitation, oxygen delivery is more dependent on tissue perfusion than arterial oxygen content. These findings are, in part, behind the recommendations that prioritize early CPR in advance of ven­ tilation in this subgroup of patients. 1 5 On the other hand, the asphyxiated, respiratory arrest patient has maximal oxygen con­ sumption associated with a lactic acidosis and C0 accumula­ 2 tion such that delays in oxygenation and ventilation should not occur during resuscitation efforts.

S U M MARY Bag-mask-ventilation remains an important potentially life-saving airway management skill. However, it can be a difficult skill to teach, learn, and perform adequately unless one does so on a regu­ lar basis. The advent of EGDs that are easy to teach, learn, and use may supplant BMV as a first-line airway management technique. Difficult mask-ventilation will usually respond to corrective measures and IMV is uncommon in experienced hands. Predicting difficult or impossible BMV is never foolproof but is fundamental to the practice of advanced airway management, influencing decision making as to how to proceed.

REFERENCES I. Link MS, Berkow LC, Kudenchuk PJ, et al. Part 7: Adult advanced cardiovascular life support: 20 1 5 American heart association guidelines update for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation. 20 1 5 ; 1 32 ( 1 8 suppl 2) :S444-S464. 2. Studnek JR, Thestrup L, Vandeventer S, et al. The association between prehospital endotracheal intubation attempts and survival to hospital dis­ charge among out-of-hospital cardiac arrest patients. Acad Emerg Med. 20 1 0 ; 1 7(9) : 9 1 8-92 5 . 3 . Gausche M, Lewis RJ, Stratton SJ, e t a l . Effect of out-of-hospital pedi­ atric endotracheal intubation on survival and neurological outcome: a controlled clinical trial. JAMA. 2000;283 (6) :783-790. 4. Stockinger ZT, McSwain NE Jr. Prehospital endotracheal intubation for trauma does not improve survival over bag-valve-mask ventilation. J Trauma. 2004;56(3) : 53 1 -536. 5 . Hasegawa K, Hiraide A, Chang Y, Brown DFM. Association of prehospi­ tal advanced airway management with neurologic outcome and survival in patients with out-of-hospital cardiac arrest.]AMA. 20 1 3;309(3):257-266. 6. Fouche PF, Simpson PM, Bendall J, Thomas RE, Cone DC, Doi SA. Airways in out-of-hospital cardiac arrest: systematic review and meta­ analysis. Prehospital Emerg Care. 20 1 4; 1 8 (2):244-256.

7. Tiah L, Kajino K, Alsakaf 0, et a!. Does pre-hospital endotracheal intu­ bation improve survival in adults with non-traumatic out-of-hospital car­ diac arrest? A systematic review. West] Emerg Med. 2 0 1 4; 1 5 (7):749-757. 8 . Carlson JN, Wang HE. Does intubation improve outcomes over supra­ glottic airways in adult out-of-hospital cardiac arrest? Ann Emerg Med. 2 0 1 6;67(3) :396-398. 9. Wang HE, Yealy OM. Managing the airway during cardiac arrest. ]AMA. 20 1 3;309 (3) :285-286. 10. Pepe PE, Roppolo LP, Fowler RL. Prehospital endotracheal intubation: elemental or detrimental? Crit Care. 20 1 5 ; 1 9 ( 1 ) : 1 -7. 1 1 . Benoit JL, Prince OK, Wang HE. Mechanisms linking advanced airway management and cardiac arrest outcomes. Resuscitation. 20 1 5 ;93: 1 24- 1 27. 12. Benoit JL, Gerecht RB, Steuerwald MT, McMullan JT. Endotracheal intubation versus supraglottic airway placement in out-of-hospital car­ diac arrest: A meta-analysis. Resuscitation. 20 1 5 ;93 :20-26. 1 3 . 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Shin SO, Ahn KO, Song KJ, Park CB, Lee EJ. Out-of-hospital airway management and cardiac arrest outcomes: A propensity score matched analysis. Resuscitation. 2 0 1 2;83(3) : 3 1 3-3 1 9. 24. Grein AJ, Weiner GM. Laryngeal mask airway versus bag-mask venti­ lation or endotracheal intubation for neonatal resuscitation. Cochrane Database Syst Rev. 200 5 ; (2) :CD0033 1 4 . 2 5 . Kurola ] 0 , Turunen MJ, Laakso JP, Gorski JT, Paakkonen HJ, SilfVast TO. A comparison of the laryngeal tube and bag-valve mask ventilation by emergency medical technicians: a feasibility study in anesthetized patients. Anesth Ana/g. 2005; I 0 1 (5): 1 477- 1 48 1 . 26. Oiirges Y, Wenzel Y, Knacke P, Gerlach K . Comparison o f different airway management strategies to ventilate apneic, nonpreoxygenated patients. Crit Care Med. 2003;3 1 (3): 800-804. 27. Murray MJ, Vermeulen MJ, Morrison LJ, Waite T. Evaluation of prehos­ pital insertion of the laryngeal mask airway by primary care paramedics with only classroom mannequin training. C]EM. 2002;4 (5): 338-343. 28. Dorges V, Wenzel V, Knacke P, Gerlach K. Comparison of different airway management strategies to ventilate apneic, nonpreoxygenated patients. Crit Care Med. 2003; 3 1 (3): 800-804. 29. Murray MJ, Vermeulen MJ, Morrison LJ, Waite T. Evaluation of prehos­ pital insertion of the laryngeal mask airway by primary care paramedics with only classroom mannequin training. C]EM. 2002;4 (5): 338-343. 30. Mi.iller J-U, Semmel T, Stepan R, et al. The use ofthe laryngeal tube dispos­ able by paramedics during out-of-hospital cardiac arrest: a prospectively observational study (2008-20 1 2 ) . Emerg Med]. 20 1 3;30 ( 1 2) : 1 0 1 2- 1 0 1 6. 3 1 . Trevisanuto 0, Cavallin F, Nguyen LN, et al. Supreme laryngeal mask airway versus face mask during neonatal resuscitation: a randomized con­ trolled trial. ] Pediatr. 20 1 5 : 1 -7. 32. Khoury A, Hugonnot S, Cossus J, et al. From mouth-to-mouth to bag­ valve-mask ventilation: evolution and characteristics of actual devices­ a review of the literature. Biomed Res Int. 20 1 4 : 1 -7. 33. Chrimes N. Not all bag-valva-mask devices are created equal: beware a possible lower Fi02 during spontaneous vetilation. Anaesth intensive Care. 2 0 1 4;42 (2) :276.

Bag-Mask-Venti l ation 34. Priebe HJ. Assessment of anaesthetists' ability to predict difficulty of bag­ mask ventilation. Br J Anaesth. 20 1 4 ; 1 1 2 (4):769-770. 35. Benumof JL. Management of the difficult adult airway. With spe­ cial emphasis on awake tracheal intubation. Anesthesiology. 1 9 9 1 ; 75(6) : 1 087- 1 1 1 0 . 3 6 . Cormack RS, Lehane J. Difficult tracheal intubation i n obstetrics. Anaesthesia. 1 984;39 ( 1 1 ) : 1 1 05- 1 1 1 1 . 37. Mallampati SR, Gatt SP, Gugino LD, et a!. A clinical sign to predict difficult tracheal intubation: a prospective study. Can Anaesth Soc }. 1 98 5 ;32(4) :429-434. 38. Kheterpal S, Healy D, Aziz MF, et al. Incidence, predictors, and outcome of difficult mask ventilation combined with difficult laryngoscopy: a report from the multicenter perioperative outcomes group. Anesthesiology. 20 1 3; 1 1 9 (6) : 1 360- 1 369. 39. Kheterpal S, Martin L, Shanks AM, Tremper KK. Prediction and out­ comes of impossible mask ventilation: a review of 50,000 anesthetics. Anesthesiology. 2009; 1 1 0 (4) :89 1 -897. 40. Kheterpal S, Han R, Tremper KK, et a!. Incidence and predictors of difficult and impossible mask ventilation. Anesthesiology. 2006; 1 0 5 (5 ) : 8 8 5-89 1 . 4 1 . Yildiz TS, Solak M , Taker K. Th e incidence and risk factors o f difficult mask ventilation. ] Anesth. 2005 ; 1 9 ( 1 ) :7- 1 1 . 42. Langeron 0 , Masso E , Huraux C , et a!. Prediction o f difficult mask ven­ tilation. Anesthesiology. 2000;92 (5): 1 229- 1 236. 43. Valois-G6mez T, Oofuvong M, Auer G, Coffin D, Loerwiriyakul W, Correa JA. Incidence of difficult bag-mask ventilation in children: a pro­ spective observational study. Paediatr Anaesth. 20 1 3;23 ( 1 0) : 920-926. 44. Law JA, BroemlingN, Cooper RM, et a!. The difficult airway with recommen­ dations for management-part !--difficult tracheal intubation encountered in an unconscious/induced patient. Can J Anesth. 20 1 3;60(1 1 ) : 1 089- 1 1 1 8 . 45. Frerk C, Mitchell VS, McNarry AF, e t al. Difficult Airway Society 20 1 5 guidelines for management o f unanticipated difficult intubation in adults. Br} Anaesth. 20 1 5 ; 1 1 5 (6): 827-848. 46. Benumof JL. Management of the difficult adult airway. With special emphasis on awake tracheal intubation. Anesthesiology. 1 99 1 ;75 (6) : 1 087- 1 1 1 0 . 4 7 . El-Orbany M, Woehlck H). Difficult mask ventilation. Anesth Ana/g. 2009 ; 1 09(6): 1 870- 1 8 80. 48. Kheterpal S, Healy D, Aziz MF, et al. Incidence, predictors, and outcome of difficult mask ventilation combined with difficult laryngoscopy: a report from the multicenter perioperative outcomes group. Anesthesiology. 20 1 3; 1 1 9 (6) : 1 360- 1 369. 49. Han R, Tremper KK, Kheterpal S, O'Reilly M. Grading scale for mask ventilation. Anesthesiology. 2004; 1 0 1 ( 1 ) :267. 50. Priebe H-J. Should anesthesiologists have to confirm effective face­ mask ventilation before administering the muscle relaxant? J Anesth. 20 1 6;30 ( 1 ) : 1 32- 1 37. 5 1 . Joffe AM, Ramaiah R, Donahue E, et al. Ventilation by mask before and after the administration of neuromuscular blockade : a pragmatic non­ inferiority trial. BMC Anesthesia!. 20 1 5 : 1 -9. 52. Ramachandran SK, Kheterpal S. Difficult mask ventilation: Does it mat­ ter? Anaesthesia. 20 1 1 ;66(suppl 2) :40-44. 53. Levitan RM , Everett WW, Ochroch EA. Limitations of difficult airway prediction in patients intubated in the emergency department. Ann Emerg Med. 2004;44(4) :307-3 1 3 . 5 4 . Brown CA , Bair AE, Pallin DJ, Walls RM , NEAR I I I Investigators. Techniques, success, and adverse events of emergency department adult intubations. Ann Emerg Med. 20 1 5 ;65 (4): 363-370.e l . 5 5 . Brown CA 3rd, Cox K, Hurwitz S, Walls RM . 4,87 1 Emergency airway encounters by air medical providers: a report of the air transport emer­ gency airway management (NEAR VI: "A-TEAM") project. West} Emerg Med. 20 1 4; 1 5 (2) : 1 88- 1 93. 56. Kerslake D, Oglesby AJ, Di Rollo N, et al. Tracheal intubation in an urban emergency department in Scotland: a prospective, observational study of 3738 intubations. Resuscitation. 20 1 5;89 :20-24. 57. Brown CA III, Cox K, Hurwitz WR. 4,87 1 emergency airway encoun­ ters by air medical providers: a report of the air transport emergency airway management (NEAR VI: "A-TEAM") project. WestJ Emerg Med. 20 1 3;26( 1 ) : 2 1 7-220. 58. Hillman DR, Plan PR, Easrwood PR. The upper airway during anaesthe­ sia. Br} Anaesth. 2003;9 1 ( 1 ) : 3 1 -39. 59. McGee JP II, Vender JS. Chapter 1 4 - nonintubation management of the airway: mask ventilation. 2007:345-370. 60. Adnet F, Baillard C, Barron SW, et a!. Randomized study comparing the "sniffing position" with simple head extension for laryngoscopic view in elective surgery patients. Anesthesiology. 200 1 ; 9 5 (4): 836-84 1 . 6 1 . Levitan RM , Mechem CC, Ochroch EA, Shafer FS, Hollander JE. Head-elevated laryngoscopy position: improving laryngeal exposure

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during laryngoscopy by increasing head elevation. Ann Emerg Med. 2003;4 1 (3) :322-330. lsono S, Tanaka A, Ishikawa T, Tagairo Y, Nishino T. Sniffing posi­ tion improves pharyngeal airway patency in anesthetized patients with obstructive sleep apnea. Anesthesiology. 2005 ; 1 03 (3):489-494. Mitterlechner T, Paal P, Kuehnelt-Leddhin L, et al. Head position angles to open the upper airway differ less with the head positioned on a sup­ port. Am J Emerg Med. 20 1 3 ;3 1 ( 1 ) :80-8 5 . Sara Y, Ikeda A , Ishikawa T, !son o S . How can w e improve mask ventila­ tion in patients with obstructive sleep apnea during anesthesia induction? } Anesth. 20 1 3;27 ( 1 ) : 1 52- 1 56. Alterman FR, Munoz HR, Delfino AE, Cortinez LI. Pre-oxygenation in the obese patient: effects of position on tolerance to apnoea. Br}Anaesth. 2005;95(5):706-709. Davies JD, Costa BK, Asciutto AJ. Approaches to manual ventilation. Respir Care. 20 1 4 ; 5 9 (6) : 8 1 0-824. Kovacs G, Law JA, eds. Airway Management in Emergencies. 1 st ed. New York, NY: McGraw Hill; 2007. Uzun L, Ugur MB, Altunkaya H, Ozer Y, Ozkocak I, Demirel CB. Effectiveness of the jaw-thrust maneuver in opening the airway: a flex­ ible fiberoptic endoscopic study. ORL J Otorhinolaryngol Relat Spec. 2005;67( 1 ) : 39-44. Boidin MP. Airway patency in the unconscious patient. Br J Anaesth. 1 98 5 ; 57(3) : 306-3 1 0 . Morikawa S, Safar P, Decarlo J. Influence of the headjaw position upon upper airway patency. Anesthesiology. 1 9 6 1 ;22:265-270. Apfelbaum JL, Hagberg CA, Caplan RA, et al. Practice guidelines for management of the difficult airway: an updated report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology. 20 1 3 ; 1 1 8 (2) :25 1 -270. Piepho T, Cavus E, Noppens R, et a!. S 1 guidelines on airway manage­ ment. Anaesthesist. 20 1 5 ;64(S l ) :27-40. Sim M a B, Dean P, Kinsella J, Black R, Carter R, Hughes M. Performance of oxygen delivery devices when the breathing pattern of respiratory fail­ ure is simulated. Anaesthesia. 2008;63 (9) :93 8-940. Pandit )J, Duncan T, Robbins PA. Total oxygen uptake with rwo maximal breathing techniques and the tidal volume breathing technique: a physi­ ologic study of preoxygenation. Anesthesiology. 2003;99(4) :84 1 -846. Groombridge C. Chin CW, Hanrahan B, Holdgate A. Assessment of common preoxygenation strategies outside of the operating room envi­ ronment. Acad Emerg Med. 20 1 6;23(3) :342-346. Weingart SD, Levitan RM . Preoxygenation and prevention of desatu­ ration during emergency airway management. Ann Emerg Med. 2 0 1 2;59(3): 1 65 - 1 75 . Harbut P, Gozdzik W, Stjernfalt E , Marsk R , Hesselvik J F. Continuous positive airway pressure/pressure support pre-oxygenation of morbidly obese patients. Acta Anaesthesia! Scand. 2 0 1 4 ; 5 8 (6) :675-680. Sellick BA. Cricoid pressure to control regurgitation of stomach contents during induction of anaesthesia. Lancet. 1 9 6 1 ;2(7 1 99):404-406. lsono S . facemask ventilation during induction of anesthesia how "gentle" is "gentle" enough? Anesthesiology. 20 1 4; (2):20 1 3-20 1 5 . El-Orbany M, Connolly LA. Rapid sequence induction and intubation: Current controversy. Anesth Ana/g. 20 1 0 ; 1 1 0 (5): 1 3 1 8- 1 32 5 . Algie C M , Mahar RK, Tan H B , Wilson G, Mahar P D , Wasiak ). Effective­ ness and risks of cricoid pressure during rapid sequence induction for endo­ tracheal intubation. Cochrane database Syst Rev. 20 1 5; 1 1 (4) :CD0 1 1 656. Brown P, Werret G. Bag-mask ventilation in rapid sequence induction: A survey of current practice among members of the UK Difficult Airway Society. Eur JAnaesthesia!. 20 1 5 ;32(6):446-448. Brown JPR, Werrett G. Bag-mask ventilation in rapid sequence induc­ tion. Anaesthesia. 2009;64(7) :784-785. Otten D, Liao MM, Wolken R, et a!. Comparison of bag-valve­ mask hand-sealing techniques in a simulated model. Ann Emerg Med. 20 1 4;63 ( 1 ) : 6 - 1 2.e3. Hart D, Reardon R, Ward C, Miner J. Face mask ventilation: A compari­ son of three techniques. } Emerg Med. 2 0 1 3;44(5): 1 028- 1 033. Davidovic L, LaCovey D, Pitetti RD. Comparison of 1 - versus 2-person bag-valve-mask techniques for manikin ventilation of infants and chil­ dren. Ann Emerg Med. 2005;46 ( 1 ) :37-42. Gerstein NS, Carey MC, Braude DA, et a!. Efficacy of facemask ventila­ tion techniques in novice providers. J Clin Anesth. 20 1 3;25(3) : 1 93 - 1 97. Braude DA, Tawil !, Gerstein NS, Carey MC, Petersen TR. Comparison of bag-valve-mask hand-sealing techniques in a simulated model. Ann Emerg Med. 20 1 4;63 (6) :784-78 5 . Joffe AM , Hetzel S, Liew EC. A rwo-handed jaw-thrust technique is superior to the one-handed "EC-clamp" technique for mask ventilation in the apneic unconscious person. Anesthesiology. 20 1 0; 1 1 3 (4): 873-879.

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Ai rway Tec h n i q ues 90. Mort T C . Emergency tracheal intubation: complications associated with repeated laryngoscopic attempts. Anesth Analg. 2004;99 (2) :607-6 1 3 . 9 1 . Ellis DY, Harris T, Zideman D. Cricoid pressure i n emergency depart­ ment rapid sequence tracheal intubations: a risk-benefit analysis. Ann Emerg Med. 2007;50 (6) :653-665. 92. Buder J, Sen A. Towards evidence-based emergency medicine: best BETs from the Manchester Royal Infirmary. BET I : cricoid pressure in emer­ gency rapid sequence induction. Emerg Med]. 20 1 3;30(2) : 1 63- 1 6 5 . 93. Stewart J C , Bhananker S, Ramaiah R . Rapid-sequence intubation and cricoid pressure. Int J Crit Illn Inj Sci. 20 14;4 ( 1 ) :42-49. 94. Ovassapian A, Salem MR. Sellick's maneuver: to do or not do. Anesth Analg. 2009; I 09(5): 1 360- 1 362. 95. Boer S, Duttchen K, Chan J, et a!. Cricoid pressure provides incomplete esophageal occlusion associated with lateral deviation: a magnetic reso­ nance imaging study. } Emerg Med. 20 1 2;42(5):606-6 1 1 . 96. Smith KJ, Dobranowski J, Yip G, Dauphin A, Choi PT-L. Cricoid pres­ sure displaces the esophagus: an observational study using magnetic reso­ nance imaging. Anesthesiology. 2003;9 9 ( 1 ) :60-64. 97. Zeidan AM , Salem MR, Mazoit JX, Abdullal1 MA, Ghattas T, Crystal GJ. The effectiveness of cricoid pressure for occluding the esophageal entrance in anesthetized and paralyzed patients: an experimental and observational glidescope study. Anesth Analg. 20 1 4; 1 1 8 (3 ) : 5 80-586. 98. Lawes EG, Campbell I, Mercer D. Inflation pressure, gastric insuffiation and rapid sequence induction. Br} Anaesth. 1 987; 5 9 (3) : 3 1 5-3 1 8 . 9 9 . Saddawi-Konefka D , Hung SL, Kacmarek RM , Jiang Y. Optimizing Mask Ventilation: Literature Review and Development of a Conceptual Framework. Respir Care. 20 1 5 ;60 ( 1 2) : 1 834- 1 840. 1 00. Wenzel V, ldris AH, Diirges V, et a!. The respiratory system during resus­ citation: A review of the history, risk of infection during assisted ventila­ tion, respiratory mechanics, and ventilation strategies for patients with an unprotected airway. Resuscitation. 200 I ;49 (2) : 1 23- 1 34. 1 0 1 . Bouvet L, Albert M-L, Augris C, et a!. Real-time detection of gastric insuf­ flation related to facemask pressure-controlled ventilation using ultra­ sonography of the antrum and epigastric auscultation in nonparalyzed patients: a prospective, randomized, double-blind study. Anesthesiology. 20 1 4 ; 1 20 (2):326-334. 1 02. Davis DP, Douglas DJ, Koenig W, Carrison D, Buono C, Dunford J V. Hyperventilation following aero-medical rapid sequence intubation may be a deliberate response to hypoxemia. Resuscitation. 2007;73(3) :3 54-36 1 . 1 03 . Davis D P. Early ventilation in traumatic brain inj ury. Resuscitation. 2008;76(3) :333-340. 1 04. Davis DP, Heister R, Poste JC, Hoyt DB, Ochs M, Dunford JV. Ventilation patterns in patients with severe traumatic brain injury following para­ medic rapid sequence intubation. Neurocrit Care. 2005 ;2(2) : 1 6 5- 1 7 1 .

1 0 5 . Gabrielli A, Layon AJ, Wenzel V, Dorges V, ldris AH. Alternative venti­ lation strategies in cardiopulmonary resuscitation. Curr Opin Crit Care. 2002;8(3): 1 99-2 1 1 .

SELF - EVALUATION QU ESTIONS 8 . 1 . Functional upper airway obstruction i n the unconscious patient involves soft tissue collapse between A. the tongue and the posterior pharynx B. the epiglottis and the posterior pharynx C. the soft palate and the posterior pharynx D. the tongue and the palate E. all of the above 8.2. The most effective means of relieving a non-pathologic upper airway obstruction in the unconscious patient is A. placing the patient in sniffing position B. placing a nasopharyngeal airway C. simple extension of the neck D. performing a jaw thrust E. placing an extraglottic device 8 . 3 . Difficult mask-ventilation is associated with A. increasing age B. Mallampati II or III C. difficult laryngoscopy D. the presence of dentures E. A and C

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C H A PT E R 9

Direct Laryn goscopy Richard M. Levitan and George Kovacs

H I STO RY A N D BACKG ROU N D.

1 55

EQUI PMENT .

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BIOMECHANICS A N D O PTICS . . . . . . . . . . . . . . . . . . . . . 1 60 D I F F I C U LT LARYNGOSCOPY-ASSESSMENT AND PREDICTION. . . . . . . . . . . . . . . . . . . . . . . . .

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PREPAR I N G FOR LARYNGOSCOPY-O PT I M I Z I N G CON DITI O N S . . . . . . . . . . . . . . . . . . . . . . 1 63 ANATO M I C C O N S I D E RATI O N S A N D L AYNGOSCOPY TEC H N I Q U E . . .

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EN DOTRACH EAL TU B E PLACEMENT .

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S U M MARY . . . . . . . . . . . . . . . . .

1 69

SELF-EVALUATIO N Q U ESTIO N S .

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H I STORY AND BACKG ROU N D I n this day and age with video-laryngoscopy (VL) rapidly becom­ ing the standard of care for orotracheal intubation (OTI) one might rightly ask if there is still a need for a chapter on direct laryngoscopy (DL) . However, while VL is gaining ground on DL it has yet to replace it as the most common device employed to facilitate OTI, and it will remain a vitally important skill to master for difficult and failed intubation rescue, and in parts of the world that cannot afford or do not have access to VL. • What Is the History and Evolution of Direct

Laryngoscopy and Tracheal I ntubation?

In the modern era, DL is almost exclusively associated with tracheal intubation, even though the procedure was initially

developed for diagnosing and treating laryngeal pathology. Following the development of mirror laryngoscopy in the 1 800s (Czermark and others) , Kirstein reported the first DL in 1 89 5 . 1 Over the next 20 years, the basic tenets of the procedure were refined by surgeons interested in laryngeal examination and surgical exposure. A step-wise approach, the focus on epiglottoscopy, recog­ nition of posterior laryngeal landmarks, optimal positioning for laryngeal exposure, and the benefits of external laryn­ geal manipulation and head elevation, etc., are all detailed by Chevalier Jackson2 in his 1 922 text, Bronchoscopy and

Esophagoscopy, A Manual for Peroral Endoscopy and Laryngeal Surgery. With the evolution of modern anesthesia, the original straight laryngoscope designs by ENT surgeons gave way to instruments specifically designed for tracheal intubation, such as the straight Magill ( 1 930)3 and Miller blades ( 1 94 1 )4 and the curved Macintosh blade ( 1 943) .5 It was also in this time period that the modern design of a detachable blade and bat­ tery handle became commonplace. Berween the 1 9 30s and 1 970s, many different laryngoscope blades were designed to facilitate intubation (e.g. , Wisconsin, Phillips, Guedel, etc.), but the Magill, Miller, and Macintosh models (albeit with some modifications) remain universally used, and in most settings, are the only laryngoscope blades available. The development of flexible fiberoptics, subsequent attach­ ment of fiberoptics to rigid blades (Bullard laryngoscope, WuScope, etc.) , and more recently video laryngoscopes (Glidescope, McGrath, Storz Video MAC, etc.) have narrowed the clinical role of standard, line-of-sight (LOS) , DL, and now there is a wide array of indirect visual devices for both diag­ nostic imaging of the larynx and tracheal intubation. Direct laryngoscopy remains the predominant method of tracheal intubation. Alternative devices, however, are being increas­ ingly deployed for both routine and anticipated "difficult laryngoscopy."

1 56

Ai rway Tec h n i q ues

Straight blades, such as the Magill blade (see Chapter 1 , Figure 1 - 1 ) , were originally designed to "pick up" the epiglot­ tis and elevate it directly, while the curved Macintosh type blades are intended to be advanced into vallecula and indirectly elevate the epiglottis by applying pressure to the hyoepiglottic ligament. These factors illustrate two distinguishing features of these blade designs: that straight blades are inserted more deeply than curved blades; and that curved blades have an atraumatic tip design to reduce the risk of vallecular injury. Because laryngoscopy was originally an operative technique where the practitioners needed their dominant right hand (85% of the population is right hand dominant) to be free to operate, the laryngoscope became by default a left-handed instrument. Laryngoscopy and intubation are performed through the right side of the mouth. The left hand is used to ins �rt the laryngoscope blade into the mouth to expose the glows. The right hand is then free to perform a variety of tasks includ­ ing the insertion of an intubation aid (e.g., Eschmann Trac� eal Introducer, [ETI] ) , manipulate the larynx, lift the head, suction the airway, and ultimately, pass the tube.

EQU I PM E NT • What Are the Principal Design Com ponents

of Laryngoscopy Blades and How Do th �y Work to Facilitate Endotracheal lntubat1on?

Laryngoscope blade design, light, and battery systems affect procedural performance since they impact on illumination, laryngeal exposure, and endotracheal tube (ETT) delivery. This holds true for both straight and curved laryngoscope blade designs, but because these designs function differently, there are different considerations (see below) . The principal components of a laryngoscope blade are the spatula (that passes over the lingual surface of the tongue) and the Bange that is used to direct the tongue (Figure 9-1) , a Buid filled non-compressible structure, to the side of the mouth and into the mandibular space (the space below the tongue) . This concept of "mandibular space volume" is particularly impor­ tant in clinical practice as the practitioner evaluates for difficult laryngoscopy and intubation (see Chapter 1 ) .

Cu rved (Maci ntosh) Distal end

Proxi mal end

Fla nge

Hook-on base Electrical contact

Straight (Mil ler)

� o�

Tongue

Fla nge

-

Web

Usable length

F I G U R E 9-1 . Des i g n of the l a ryngoscope b l a des.

Di rect La ryng oscopy

Early pioneers, such as MagilV employing straight blades recognized that tongue displacement to one side facilitated laryngeal visualization, particularly if the blade of the laryn­ goscope was inserted in the corner of the mouth and along the paraglossal gutter. Importantly, it was recognized that this "paraglossal" or "retromolar" technique optimized the laryngeal view mostly because it shortened the distance between the teeth and the larynx (i.e., the molars are closer to the larynx than the incisors) . The other benefit of right paraglossal laryngoscopy is that the rigid laryngoscope blade impacts the molar teeth rather than the relatively more fragile central incisors. The flange of the laryngoscope remains a threat to dentition and should never be leveraged backward against the teeth. Straight blade laryngoscopes tend to have smaller displace­ ment volumes (defined by the dimensions of the spatula and flange) than curved designs. It is logical, therefore, that straight blades (and a paraglossal approach) are favored in patients who have a small mandibular volumes into which the tongue is dis­ placed (or "compressed") during DL. Examples of such patients are small children (below the age of 8, but especially below age 5) and adults who have a receding chin. • What Are the Varia bles that Determ ine

the I l l u m i nation Created by a Laryngoscope Blade?

Illumination is critically important for DL. Bright light is nec­ essary for tissue edge and color discrimination, and the identi­ fication of tissues and structures. This is particularly important in preterm infants where the appreciation of subtle color differ­ ences is critical to intubation success. Laryngoscope lighting systems can be divided into those with a light source mounted directly on the blade (bulb-on­ blade) , and those in which the light source is at the top of the handle (bulb-on-handle) . Bulb-on-blade designs (sometimes referred to as conven­ tional blades) have a simple electrical connection between the bulb socket on the blade and the handle (with enclosed batteries) . This connection is very robust and less subject to malfunction than the spring-loaded, on-off lights used with bulb-on-handle systems. These removable bulbs can usually be replaced if they fail. This feature confers the risk that should the bulb become loose it may flicker during operation, or worse yet, become dislodged and lost into the patient.6'7 To eliminate this risk, some manufacturers fuse the bulb to the blade rendering the bulb non-replaceable. Laryngoscope bulbs for both designs are of several types: incandescent filament (tungsten with halogen gas) , xenon gas, and light-emitting diodes (LED) . The bulb itself can have either a frosted or clear lens, and may incorporate a reflector (common with bulb-on-handle designs) . Compared to other light producing systems, LED bulbs use very little energy, operate with less heat, and have a much longer life span, thereby eliminating bulb replacement as a major concern. They now can be produced at less cost than other bulbs and produce brilliant light. The light from an LED tends to be whiter and bluer than traditional bulbs. All of the newer intubation devices (video laryngoscopes, mirror

laryngoscopes, chip-on-stick CMOS imaging devices, etc.) use LED lights . With bulb-on-handle systems, a light-conducting fiber, made of either glass or plastic, conveys the light from the top of the handle to the distal portion of the blade. Although such blades are often called "fiber-optic," they have no optical fibers, per se, and a more appropriate term is "fiber-lit." Glass fibers conduct light more efficiently, but cost significantly more. Disposable blades commonly use a light-conducting bundle made of plastic, whereas non-disposable fiber-lit blades all use glass fiber bundles. In the United States, any blade or handle that uses fiber illumination has a green dot on the blade base and a green circle at the top of the handle (commonly referred to as a "green-line handle"). It is important for practitioners to appreciate that fiber-lit blades and handles and conventional blades and handles are not interchangeable. A critical and essentially unexamined area of laryngoscope illumination involves batteries. 8 Alkaline batteries have a gradually declining discharge curve. Failure to appreciate and rectify this declining illumination may compromise DL by low light, heralded by a difficult or failed intubation. Lithium batteries have a much flatter, higher discharge curve than alkaline batteries, but fail precipitously once the energy output falls below a certain threshold. Lithium batteries are much more expensive and generate more heat than alkaline batteries. Some manufacturers, especially those producing high­ quality fiber-lit blades, offer nickel-metal-hydride rechargeable battery systems, which produce very intense light when com­ bined with a xenon bulb and glass fibers. While the light output from these high-end fiber-lit systems is impressive, they are very expensive. Newer LED technology has the potential to rival the light output of these systems at a fraction of their cost, draw little energy, and are offered in a single-use, disposable, bulb-on­ blade design. Regardless of the type of light, the intensity of light reach­ ing the distal end of a laryngoscope blade is dependent on the distance the light must travel. This phenomenon is governed by the inverse square law of physics: that is if the distance from the light source to an object is doubled, the resultant amount of light energy reaching the object is reduced to one quarter of the original amount. So, generally, blade designs with shorter light-to-tip distances create more intense distal light. This pro­ duces substantial variability in the amount of light emitted by different combinations of blades and handles used in clinical practice. In a study conducted in emergency departments, there was a 500-fold difference in light output between the best and worst blade-handle combinations.9 Few clinical settings monitor the light output with light meter testing. Lighting standards in dentistry or surgery rec­ ommend 5000 lux. 10 While there is no well-accepted light intensity standard for the laryngoscopes, the International Organization for Standardization has suggested 700 lux as a minimum light output for laryngoscopes. 1 1 In the presence of blood, secretions, and vomitus, common to emergency airways, more light is needed to discriminate landmarks.

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• What Are the Distinguishing Features

of Commonly Used Curved (Maci ntosh) Blade Designs?

The term "Macintosh blade" is generally used to mean any curved blade. However, since Macintosh's5 original description in 1 943, several variations have been produced that are distin­ guishable by their flange height, flange shape, light position, and light type. These designs are commonly designated by their geographic manufacturing origins, i.e., American (commonly known as "Standard") , English (commonly known as "Classic") , and German designs. The common features are a gently curved spatula and a large reverse Z-shaped flange (Figure 9- 1 ) . American blades closely follow Macintosh's original descrip­ tion, that is, a large vertical, square-shaped, proximal flange that does not extend to the distal tip, coupled with a bulb-on­ blade illumination system. The English design has a smaller, curvilinear proximal flange that runs all the way to the distal tip, and also uses a conventional light. Heine of Germany devel­ oped a fiber-lit blade that follows the English contour in terms of a short proximal flange. A large rectangular-shaped 5-mm glass fiber bundle is incorporated in the flange. The English and German designs have a much shorter light-to-tip distance than the American design (Figure 9-2) . Most American designs use a frosted bulb, while most English designs have a clear lens. American and English designs now offer fiber illumination options. Numerous manufacturers around the world now offer "American," "English," and "German" curved blades, and many blades have a mix of features. It is interesting to note that Macintosh envisioned one adult size for his blade (corresponding to approximately a Macintosh size 3) . Market demand leads to the current variety of pediat­ ric and adult sizes available. Size selection is largely a matter of patient's size and practitioner's choice. No matter the size chosen, it should be noted that the most common error of the novice is inserting the blade too deeply and into the upper esophagus before visualization is performed. The shorter light-to-tip dis­ tance (and light source common to German or English designs) also provides better illumination relative to the American design.

A recent variation of the Macintosh design is the McCoy (also known as Corazelli-London-McCoy [CLM] ) levering laryngoscope blade (Figure 9-3) . This blade is a Macintosh design with an articulating distal tip that when activated is intended to elevate the tissue at the base of the tongue (improving epiglottis lift and laryngeal exposure) . This blade has become quite popular in the United Kingdom (where it originated) , but published clinical investigations have reported mixed results. 1 2-17 • What Variations Exist Between Mil ler Blade

Laryngoscope Designs?

Robert Miller's straight blade design in 1 94 1 adapted the straight shape of early laryngoscopes, in particular that of Magill (see Figure 1 - 1 ) , but added a slightly upturned distal tip and narrower flange.4 The flange had a compressed 0 shape (when viewed longitudinally) with a height large enough to accept a 37 French Argyle tube. Compared to tubular-shaped blades (Jackson-Wisconsin, for example) , the much shallower proxi­ mal flange was intended to minimize dental injury (Figure 9-4) . The light was situated at the distal tip o n the right side o f the

F I G U R E 9-3. The McCoy (a l s o known as Coraze l l i-London-McCoy [CLM]) l everi n g l a ryngoscope b l a d e. Light-to-ti p distance

Cranwa l l

M i l ler

P h i l l i ps

Wisconsin

Guedel

Germ a n #4

F I G U R E 9-2. Des i g n of the cu rved Maci ntosh l a ryngoscope b l a d es: the Germ a n d e s i g n has a much s h o rte r l i g ht-to-t i p d i sta nce t h a n the Am erica n d es i g n .

F I G U R E 9-4. Different design of the stra i g h t l a ryngoscope blades with different tubular s h a pes.

Di rect La ryng oscopy

spatula, opposite the flange side, and tilted toward midline (Figure 9- 1 ) . Since Miller's original description, various manufacturers have compressed the flange height, and some have changed the bulb location (to the left flange edge, or recessed within the flange) . Designs with light sources located on the exposed edge of the left flange are less preferred by some since a light at this location can become embedded in the tongue with resultant poor illu­ mination. Most Miller designs currently made for adults cannot accommodate an adult-sized cuffed ETT down the barrel. In addition, tube passage down the barrel blocks the LOS to the target. The very narrow design of modern Miller blades neces­ sitates careful paraglossal placement (the small flange cannot sweep the tongue) and the extreme right corner of the mouth (which often requires manual retraction by an assistant) must be used for tube delivery. Alternatively, an ETI can be employed. Another challenge of the narrow flange straight blades is that it makes landmark recognition down the barrel difficult. • What Is the "Straight-Blade Paradox?"

Landmark recognition and ease of tube delivery improve as the flange height and spatula size of a straight blade are increased. Paradoxically, it gets harder to introduce the blade alongside the tongue, and reach the larynx, as the displacement volume of the blade increases. This was known to Miller, who shortened his flange height, but left the resulting 0-shaped barrel large enough to accept an ETT. Straight blade designs with larger flanges (and spatulas) than the Miller design include the Phillips (a 2/3 small "C"-shape flange) , Wisconsin (a higher, nearly full "C" -shaped flange) , and the Guedel (a very large, sideways "U" -shaped flange and spatula) (Figure 9-4) . The Henderson straight blade has small incomplete 2/3 "C" -shaped flange that is large enough for tube delivery. It also has a uniquely visible distal tip (a knurled edge at the distal blade tip is visible when viewed down the barrel) , and a large, recessed, fiber bundle light source (Figure 9-5) .

F I G U R E 9-S. The Henderson l a ryngoscope.

• Apart from the McCoy and Henderson

Blades Already Mentioned, Are there Other Recent Blade Designs that Might be of Use?

The Dorges universal blade is intended to replace Macintosh size 2-4 blades with one blade for all patients from age 1 to adult. 18 The curve is much reduced, the spatula is tapered from proximal end to distal tip, and the proximal flange height is very short ( 1 5 mm) , allowing it to be used with children and those with limited mouth opening, while at the same time per­ mitting deeper insertion in larger adults owing to its length (Figure 9-6) . The Grandview blade is an emergency blade for adult patients that is available in two sizes . 1 9 It combines a very widen spatula with a slight overall curve and a narrow proximal flange (Figure 9-7) . The resulting blade can be used to lift the epiglot­ tis directly or indirectly.

1 25 m m ------

1 5 mm

F I G U RE 9-6. The Dorges u n iversa l l a ryngoscope blade.

F I G U R E 9-7. The G ra n dview u n iversal la ryngoscope blade.

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BIOM ECHAN I CS AND OPTICS • What Optica l and Biomechan ical

Considerations Should Practitioners Appreciate When Perform ing Direct Laryngoscopy?

Direct laryngoscopy is a procedure with inherent visual restric­ tions. Visual restrictions are created by the degree to which the mouth opens, the teeth, the tongue, the long axis view down a laryngoscope blade, and the structures about the laryngeal inlet that surround the glottic opening. Laryngeal anatomy, which is exposed in piecemeal fashion initially, must be recognized when viewed down this restricted visual space. In many instances, only a small posterior portion of the glottic opening may be vis­ ible. Passage of the ETT further adds to the visual challenge. It is critical for practitioners to know laryngeal anatomy in detail, to anticipate the sequence and appearance of structures as they come into view, and to be aware of how visual restrictions and biomechanics impact on laryngeal exposure and tube delivery. • What Is the Best Way to Maxim ize Mouth

Open ing and Jaw Distraction for Laryngeal Exposure and Tube Insertion?

As has been previously mentioned, employing the right corner of the mouth for laryngoscope blade insertion and tube passage is essential. A paraglossal approach is absolutely essential with straight blades. Even with curved blades, midline placement of the blade must be avoided because it will create "tongue flop" on each side of the blade, restricting glottic exposure and tube delivery. The amount of mouth opening possible is a function of jaw distraction, and head and neck positioning. Positioning that facilitates jaw distraction and mouth opening is important in all patients, but most critical in the obese. Supine patients without cervical spine immobilization or known cervical pathology are optimally positioned for laryngoscopy when the external audi­ tory meatus and sternal notch are horizontally aligned when viewed from the patient's side (see Chapter 20, Figures 20- 1 and 20-2) . This is called "ear-to-sternal notch" or "ramped" position. The traditional "sniffing position" is created by a combina­ tion of neck flexion and head extension at the atlanto-occipital joint. Ear-to-sternal notch positioning usually requires 8 to 1 0 centimeters of elevation under the occiput, generally much more head elevation than that produced by the standard "sniff­ ing" position. Furthermore, standard sniffing position posture fails to take into account size-related anatomical variations of the respiratory tract as it transitions from the thorax through the head and neck. On the other hand, ear-to-sternal notch positioning takes this variation into account permitting exter­ nal landmark-based patient positioning to be individualized. These anatomical variations are most frequently appreciated in individuals who are obese and morbidly obese. In such patients, a ramp may be several feet high and incorporate support under the upper torso and shoulders as well as the head to achieve proper alignment. Head elevation and ramping in this man­ ner optimize laryngoscopy, and while at the same time offer improved gas exchange mechanics.

When performing laryngoscopy with the patient supine, along with ear-to-sternal notch positioning, the face plane of the patient should be parallel to the ceiling (see Figure 20-2) . A common error is to overextend or tilt the head backwards. 2 Atlanto-occipital extension may push the base of tongue and epiglottis against the posterior hypo-pharyngeal wall. Not only does this make recognition of the epiglottis more difficult upon blade insertion, but also narrows the space available to pass the laryngoscope and restricts laryngeal exposure. Extension alone may also create tension on the anterior neck muscles opposing simultaneous efforts to open the mouth and distract the jaw. Successful laryngoscopy in this position requires that the patient's head be below the practitioners xiphoid process, a position recommended by some texts. The reason for this is that increasing head elevation dynamically during laryngoscopy if laryngeal exposure is inadequate is made easier. 2 0 Dynamic head elevation cannot be done on the morbidly obese and these patients must be ramped into a proper position in advance (see Figure 20-2) . Mouth opening in the anesthetized or unresponsive patient usually occurs with head and neck positioning. In the event it does not, it can be achieved by simply pushing the chin in a caudad direction or by employing the cross-fingered or "scis­ sors" technique. This technique provides a more controlled and effective force than simply extending the head on the neck.

• What Is the Optimal Position for

Laryngoscopy in Patients with Known or Suspected Cervica l Spine I nju ry? Is It Safe to Perform Di rect Laryngoscopy?

Direct laryngoscopy has been shown to be safe in patients with known or suspected cervical spine injury, but it should be performed with manual in-line immobilization (MILl) (see Chapter 1 7) . There has been considerable attention and contro­ versy regarding airway management in the known or presumed c-spine injured patient. 21-23 Some would argue that this concern has led to unnecessary delay in managing the trauma airway, a decision which in some cases could result in increased morbid­ ity and mortality (e.g. , hypoxemia and/or hypercarbia in head injured patients) . As a result, Advanced Trauma Life Support (ATLS) has backed away from an earlier recommendation that C-spine imaging precede airway management. Furthermore, there is little evidence to support secondary spinal cord injury directly attributable to airway management. 22-24 Despite the fact that MILl does not completely prevent c-spine motion, it remains a recommendation. Care should be taken to ensure proper application of MILl in such a manner that mouth open­ ing is not limited. Mouth opening is markedly limited with a collar in place where epiglottis-only views (or worse) can occur in more than 60% of cases. 2 5 Properly performed MILl will reduce the incidence of an epiglottis-only view to 22%. 26 Research comparing intubation devices have revealed no convincing superiority of any device over well-performed DL in terms of limiting c-spine motion. 2 1 The major priority in managing suspected c-spine injured patients is how to optimize view on laryngoscopy. Indicated airway management should not be delayed in fear of causing secondary spinal cord injury.

Di rect La ryng oscopy

The use of alternative devices, such as optical stylets or VL may help overcome a challenging view, although simple maneuvers, such as the application of optimal external laryngeal manipu­ lation27 (OELM or BURP, Backwards Upwards Rightwards Pressure2 8) and the use of an ETI (commonly referred to as a "gum elastic bougie") are equally effective in managing the airway in a trauma patient with a suspected c-spine injury. 2 1 Ear-to-sternal notch positioning cannot be used in such patients. The front of a cervical collar should be removed in order to permit jaw distraction. It is also helpful to drop the foot end the stretcher while keeping the stretcher straight (i.e., "Reverse Trendelenberg") . This positions the airway higher than the stomach and may prevent passive regurgitation and improves pulmonary mechanics. An assistant must maintain MILl while laryngoscopy is carefully performed. • How Should the La ryngoscope be Gri pped

to Minimize the Work of La ryngoscopy Wh ile Maintaining Fine Control of the Blade Tip?

The mechanics of laryngoscope lift are slightly different with curved versus straight blades. With the curved blade, the tip of the blade is guided into vallecula to depress the underlying hyo­ epiglottic ligament, lifting the epiglottis forward away from the glottic inlet. With straight blades, the tip of the blade lifts the epiglottis directly. Both curved and straight blade handles should be gripped with the tips of the fingers where the handle meets the proximal blade (Figure 9-8) . The handle should be gripped low enough so that the blade is essentially an exten­ sion of the forearm. Holding the handle higher increases the length of the lever arm requiring significantly more muscular effort. When properly gripped with the thumb pointing upward on the handle, fine control and effective mechanical advantage are achieved, and levering on the upper incisors is less likely to occur. Laryngoscopy is a delicate procedure, mostly dependent on gentle positioning of and correct vector forces at the blade

F I G U R E 9-8. La ryngoscope g ri p: both cu rved a n d stra i g h t b l a d e h a n d les s h o u l d be gri pped w i t h the tips o f the fi n g ers where the h a n d l e meets the proxi m a l blade. The h a n d l e should be g ri pped l ow e n o u g h that the b l a d e i s essenti a l l y an exte n s i o n of the fore a r m .

tip. When properly positioned, the amount of force required for most patients is minimal and can be achieved by a light grip. When the blade tip is not correctly positioned, excessively forceful lifting will usually not correct the problem. Another way to maximize lifting efficacy with minimal muscular effort is to keep the left elbow adducted to your side (roughly the anterior axillary line) , not pointing outward. With the elbow in, the handle is gripped down low, the forearm is kept straight, and body weight can be used to rock forward slightly so that minimal arm strain occurs. Force is efficiently transferred along the forearm and down the long axis of the blade.

• How Is the Larynx Sig hted During Direct

Laryngoscopy and Is Performance Improved by Assu ming a Distance as Fa r as Possible from the Target?

Contrary to popular belief and traditional instruction, even with an extended arm position, it is not possible to simulta­ neously see the larynx during laryngoscopy with both eyes. 2 9 This is due to the inherent visual restrictions of DL, created by the opening of the mouth, the teeth, the tongue, the laryn­ goscope blade itself, and the structures of the laryngeal inlet. Visually, DL is similar to looking down a narrow pipe at a tar­ get the size of a quarter, from a distance of 1 4 to 1 6 inches. Both eyes can be open during the procedure, but sighting of the larynx is with the dominant eye only; the brain sub­ consciously blocks out the non-dominant image through a process called "binocular suppression." The same phenomenon occurs when looking through a peep-hole in a door, or when sighting during target sports. In situations without visual restriction, the right and left eyes have slightly different perspectives on an object, due to the distance separating the eyes in the skull. These slightly disparate views are fused into a single stereoscopic image. This cannot happen with the visual restrictions created during laryngoscopy; stereoscopic sight cannot be achieved. Because binocular suppression occurs subconsciously, even experienced latyngoscopists may not be aware of which eye they use to sight the larynx. The monocularity of laryngeal sight during laryngoscopy is evident when viewing novice intubators attempting laryngos­ copy for the first time by noting a subtle side-to-side head rota­ tion, intermittently sighting the target with one eye and then the other. The old adage that "experienced laryngoscopists maintain a distance from the target, while novices climb into the mouth" is due not to experience but rather restrictions on accommoda­ tion that occur with age. By the mid-forties, the near visual accommodation point begins to move out approximately 2 to 3 centimeters per year. By mid-fifties regardless of your under­ lying acuity, presbyopia results in the near focus point being at about arm's length. Younger practitioners have the accom­ modation flexibility to focus on near objects. These changes are exacerbated in low light conditions. The amount of light needed for laryngoscopy by the same practitioner is different at age 40 versus age 50 and 60; more light improves the near focus ability significantly and is another reason for using laryn­ goscope systems with good light output.

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• Is It Beneficial to Identify Ocu lar Dominance,

Acuity, and Accommodation Dista nce in Trainees and How Is Th is Done?

Ocular dominance, visual acuity, and accommodation should be assessed at the start of procedure training and in all practi­ tioners on the steep curve of presbyopia (mid-forties) . Ocular dominance is tested by having the practitioner perform DL on a training mannequin. After the practitioner confirms that the larynx is sighted, instruct him or her not to move their head. Selectively cover each eye, individually. When the non-dominant eye is covered, the laryngeal view is not compromised; when the dominant eye gets covered, the larynx will no longer be sighted (or it will be seen partially, off angle) . One cannot change one's natural ocular dominance. Eyedness tends to follow handedness assuming there is not unequal acuity, and since majority of the population is right­ handed, most practitioners are also right-eyed. Persons who have a difference in visual acuity (wear lenses) , or are left­ handed, have a greater likelihood of being left-eyed when it comes to laryngoscopy. Identification of ocular dominance, formal visual acuity, and accommodation testing is valuable to the trainee to proactively prevent procedural performance problems. Norwithstanding severe visual acuity problems, most accommodation issues can be addressed by corrective lenses. Unfortunately, many prac­ titioners have lenses made for either driving, or reading, not for the proper procedural distance of laryngoscopy. The proper procedural distance for a given practitioner is berween their arm held at full extension, and the arm flexed at 90 degrees. For most practitioners this is about 1 4 to 1 6 inches (35 -40 em) . Corrective lenses become a valuable aid to DL in most practitioners by their mid- to late-forties.

D I F F I C U LT LARYNGOSCOPY-ASSESSMENT A N D PREDICTION • What Factors Contribute to Difficult

Laryngoscopy and How Reliable Is Prediction?

Difficult laryngoscopy can result from rwo different issues: ( 1 ) problems with landmark recognition and (2) mechanical problems that prevent laryngeal exposure. Landmark recognition is much more difficult in the pres­ ence of blood, secretions, vomitus, or distorted anatomy from a myriad of causes, including burns, edema, and other pathol­ ogy. Successful laryngoscopy hinges on recognizing the epi­ glottis and structures of the laryngeal inlet, in addition to the glottic opening and vocal cords. The epiglottis has a mucosal appearance that is very similar to the posterior hypopharynx even without the additional challenges of fluids, vomitus, or distorted anatomy. Fluids from the oropharynx and hypophar­ ynx will collect above the epiglottis when a patient is positioned in a supine position with poor muscular tone (or after the use of muscle relaxants) . This can easily cause epiglottis edge recogni­ tion failure as the blade is inserted. Elevation of the epiglottis out of the fluids by proper jaw distraction during the first phase

of laryngoscopy, which is, in turn, a function of proper head and neck position, and avoidance of overextension may help. Because fluids are often present in the airway, it is appropriate to have a Yankauer suction immediately available. Mechanical problems that can limit laryngeal exposure include limited mouth opening, prominent dentition and overbite, a large tongue to pharynx relationship (i.e., the Mallampati score) , short thyromental distance (a small displace­ ment volume for the tongue) , and limitations of neck mobility. Although great effort has been put into devising scoring systems for predicting difficult laryngoscopy, the clinical utility of such screening tests remains very limited, particularly in emergency situations. Only about one in three emergency patients who undergo intubation can follow simple commands permitting even a basic screening assessment. Emergency patients with poor muscular tone, lying in a supine position, will almost universally have a poor and different Mallampati score and a short thyromental distance. Compounding this are those with suspected c-spine injury because they cannot undergo neck mobility testing. As reviewed by Yentis,30 it is statistically challenging to devise an effective screening test, or combination of tests, for detecting a rare outcome (failed laryngoscopy) . The trachea of a vast majority of patients can be successfully intubated with DL, and unless a screening test has extremely high specific­ ity and sensitivity, most predicted failures will be false posi­ tives. Conversely, some patients who would seem to be easy may be difficult or impossible because laryngoscopy primarily involves interaction with tissue not visible to oral inspec­ tion (the base of tongue and epiglottis, e.g., lingual tonsillar hypertrophy) . While it is important to be aware of factors that can con­ tribute to difficulty, screening performs poorly, and practitio­ ners should always plan a means of rescue gas exchange and rescue technique should DL and/or bag-mask-ventilation prove difficult or impossible.31 Much of the historical concern about diffcult laryngoscopy is no longer relevant now that there are so many effective alternative options for intubation. Combined with the availability of newer supraglottic ventilation devices, the safety margin for declaring a "can't intubate, can't oxygen­ ate" has been improved. Given the effectiveness of rescue ventilation devices, and alternative intubation methods, DL efforts should generally not exceed three attempts and in many settings (prehospital) lim­ ited to one or rwo attempts depending on practitioner's experi­ ence. Poor outcomes, i.e., hypoxemia, regurgitation, aspiration, cardiac arrest, etc., have been associated with three or more laryngoscopy attempts in emergency situations.3 2 • How Is Direct Laryngoscopic View

Articulated and How Is This Clin ically Relevant? Is Difficult Laryngoscopy Synonymous with Difficu lt I ntubation?

Laryngeal exposure is only one step in the sequence of steps leading to successful intubation employing DL. It is possible to have an excellent laryngeal view and be unable to intubate the trachea, as it can occur with tracheal stenosis, for

Di rect La ryng oscopy Grade 2A

Grade 1

Easy

Grade 3A

Grade 2B

Restricted

Grade 3B

G rade 4

Difficult

F I G U R E 9-9. Mod ified Cormack and Leh a n e g ra d i n g system of l a ryngosco pic view. (Reprod uced with perm ission from Coo k TM . A new practica l c l a s s ification of l a ry n g ea l view. A naes thesia. 2000;55 (3):274-2 79.)

example. Conversely, an epiglottis-only view can sometimes be easily intubated on first attempt using a blind technique (e.g. , with an ETI) . For laryngoscopy research and for documentation pur­ poses, different systems have been created for reporting the extent of laryngeal view. The original system of grading laryn­ geal view, developed by Cormack and Lehane,33 categorizes laryngeal exposure into four grades: grade 1 - all of the vocal cords/glottic opening; grade 2 - only the posterior aspect of the glottis is in view (depending on external laryngeal pressure, part of the vocal cords, and/or arytenoids may be in view) ; grade 3 - epiglottis-only; and grade 4 - no landmarks (not even epiglottis) . Some researchers have subdivided the CL grading system to 2A and 2B, and 3A and 3 B . A 2A view reveals at least some of the vocal cord; a 2B view is arytenoids only; a 3A view is when the epiglottis is able to be lifted off the pos­ terior hypopharynx; and 3B when it is touching the posterior wall (Figure 9-9) .34 This difference in the position of the epi­ glottis is important as a posteriorly directed epiglottis creates a relatively more anterior glottic inlet that will not be easily accessed using an adj unct such as an ETI. A moderate degree of interobserver and intraobserver variability with this scoring system is known to exist. A more statistically useful method of reporting laryngeal view is the Percentage of Glottic Opening (POGO) score, which is a numerical value from Oo/o to 1 00%. 29•35 A full 1 00% POGO score would be a full view of the glottic opening from the anterior commissure of the vocal cords to the interaryte­ noid notch between the posterior cartilages. This system better distinguishes between CL grades 1 and 2, which make up the vast majority of cases, but makes no distinction between CL 3 (including 3A vs. 3B) and 4 (both would be POGO 0) . Adnet et al.36 devised an Intubation Difficulty Scale (IDS) , which incorporates laryngeal view as well as other aspects of intubation. They proposed an IDS score that is a func­ tion of seven parameters, resulting in a progressive, quantita­ tive determination of intubation complexity. The score was intended to be used to compare difficulty of intubation under varying circumstances by isolating variables of interest. The seven parameters include: 1. 2. 3. 4. 5.

The number of attempts The number of operators The number of techniques (or devices) Cormack Lehane view grade Lifting force

6. Need for external laryngeal manipulation 7. Position of the vocal cords (abducted/adducted) There are numerous challenges when applying grading sys­ tems of laryngoscopy or intubation to patients. Fundamentally, the effectiveness of the procedure is also about the skill and abil­ ity of the practitioner. A grade 3 CL view or difficult intubation employing Adnet's scoring system may be a grade 1 view and an easy intubation in a different practitioner's hands. Direct laryngoscopy and intubation are not an objective, easily graded diagnostic test, such as coronary angiography, for example. Not only does practitioner's technique impact dramat­ ically on the result, but also the performance is not routinely graded from the practitioner's perspective, and therefore cannot be objectively assessed by other persons. With angiography, the images of dye filling the coronaries is not likely to be different when performed by a different operator, and the results can be reviewed by others. Direct laryngoscopy is dynamic, with the larynx transiently visualized during 5 to 1 5 seconds, and sighted by only one eye of the practitioner. Even if it was possible to capture what the practitioner was or actually seeing during DL and evaluate the performance, it still captures the procedural performance of only one practitioner and one event.

PREPARI NG FOR LARYNGOSCOPY­ OPTI M I Z I N G CO N DITIONS • What Is "Opti mal Laryngoscopy" and How

Should the Practitioner Prepare for Direct La ryngoscopy?

The "Optimum laryngoscopic attempt" was characterized by Benumof37 as possessing six factors: Most skilled individual 1. 2. 3. 4. 5.

Best paralysis Best position Best laryngeal manupulation Best laryngoscope blade type Best laryngoscope blade length

"Optimal laryngoscopy'' refers to a combination of the proper equipment, a preplanned laryngoscopy strategy, and ideal patient conditions that collectively create optimal condi­ tions for laryngeal exposure and first-pass intubation success. Equipment must include suction (Yankauer) , functioning oxygen delivery devices, and well functioning laryngoscopes

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with optimal illumination. Tube delivery requires appropriately sized tubes, and stylets, along with a means of managing an epiglottis-only view (ETI, and/or optical stylet) . It is critical to have oral and nasal airways and an appropriately sized rescue extraglottic device (e.g. , LMA) immediately available, should intubation fail and rescue ventilation be required. Given the wide variety of alternative intubation devices, it is also appro­ priate to have an alternative device for intubation immediately available. The importance of proper positioning, for both ventila­ tion and DL, cannot be overstated. Not only will ventilation be more effective in the ear-to-sternal notch position, but will also lengthen the time to oxygen desaturation in the patient who has been rendered apneic from their underlying condi­ tion or apnea time during rapid sequence intubation/induc­ tion (RSI) .38-40 Different methods of denitrogenation have been suggested to extend apnea time.41 These include: having the cooperative patient take eight vital capacity breaths, and tidal volume breathing for 3 to 4 minutes using high flow oxygen via a bag-mask device. However, in some patient populations, such as the young pediatric patients and patients with mor­ bid obesity and critical illness, oxygen utilization is increased while reserves may be diminished.42 Oxygen desaturation will occur rapidly following apnea in these patients, requiring early mechanical ventilation, often before adequate intubation con­ ditions (muscle relaxation) are achieved.43 Assisted ventilation in patients with low baseline saturations may be indicated dur­ ing the preintubation phase. The risk of aspiration in carefully applied BMV is much less than the risk of oxygen desaturation in the critically ill patient. Denitrogenation will allow sufficient time for laryngoscopy and intubation in most patients without pulmonary pathology before oxygen desaturation occurs (lon­ ger apnea times) . While there has been debate about the indications for muscle relaxants outside of the operating room, there is no doubt that laryngoscopy is easier, more successful, done more quickly, and with fewer attempts when relaxants are used. The use of muscle relaxants offers two other very significant advantages. It elimi­ nates the risk of active vomiting during laryngoscopy, and it permits the use of rescue ventilation devices (i.e., LMA) , should laryngoscopy fail. In emergency patients with full stomachs and short apnea times, these advantages may be important. • Is there a Role for Decompression of the

Stomach Prior to Emergency La ryngoscopy, and How Should Nasogastric Tubes Al ready in Place be Hand led?

In patients with known bowel obstruction, significant gastro­ intestinal bleeding, and perhaps in patients who have received prolonged assisted BMV (long prehospital course) , it may be helpful to decompress the bowel as much as possible prior to muscle relaxation and laryngoscopy. These patients are at sig­ nificant risk of regurgitation with the onset of muscle relaxation (see section "What Is the Role of Rapid Sequence Induction in Airway Management?" in Chapter 5 ) . Sellick recommended evacuating the stomach with a gastric tube and then removing the tube before induction of anesthesia.44 Others demonstrated

no difference in the incidence of regurgitation with or with­ out a nasogastric tube.45 It is the opinions of the authors that the nasogastric tubes should, if placed, remain in situ for the intubation.

ANATOMIC CON S I D E RATIONS A N D LAYNGOSCOPY TECH N I Q U E • What Is "Epiglottoscopy" a n d Why Is I t

Importa nt When Perform ing Laryngoscopy?

"Epiglottoscopy" emphasizes the importance of visualizing the epiglottis prior to exposing the larynx and was one of Chevalier Jackson's basic rules of laryngoscopy. 2 As an anatomic land­ mark, the epiglottis has a unique importance to laryngoscopy for numerous reasons. The epiglottis is the bridge between the starting anatomic landmark (the tongue) and the goal (the larynx) . The "relational anatomy," between the tongue, epiglottis, and larynx remains a constant despite person to person anatomic and pathologic variations. The epiglottis attaches to both the tongue and the larynx. It is connected to the base of the tongue at the vallecula. It is also the most superior aspect of the laryngeal inlet, a ring of structures that encircles the glottic opening. This ring is made up of the epiglottis, the paired aryepiglottic folds, the paired posterior cartilages, and the interarytenoid notch. Within the laryngeal inlet lies the glottic opening and vocal cords. The epi­ glottis is additionally a marker for the midline. • What Is "Epiglottis Camouflage"?

As stated earlier, the mucosal appearance of the epiglottis ts identical to that of the posterior pharyngeal wall. In a supine position, with poor muscular tone, or after the administration of muscle relaxants, the jaw and base of tongue fall backward and the epiglottis lies against the posterior pharynx. Depending upon head and neck position, and the manner in which the laryngoscope is directed, it is easy to advance past the epiglot­ tis as it is camouflaged against the pharynx. Overextension of the head, at the atlanto-occiptal joint, moves the base of the tongue and epiglottis backward, making the situation worse, as do secretions, blood, and vomitus. To overcome epiglottis camouflage and make the epiglottis edge distinctly visible, it is necessary to distract the jaw effec­ tively and lift the base of the tongue. Keeping the face plane horizontal to the floor, and elevating the head to ear-to-sternal notch position (if possible) , permits optimal jaw distraction. • What Is the Best Method for Controlling

the Tongue and How Does Tongue Control I ntegrate with Epiglottoscopy?

Effective control of the tongue is critical for straight blade use, and important as well with curved blades. Any amount of tongue positioned to the right of a narrow lumen straight blade will make target visualization and tube delivery very difficult. The small flange height, especially of some Miller designs, pre­ vents any ability to sweep the tongue, and practitioners should

Di rect La ryng oscopy

not attempt to do so. Proper position is achieved with straight blades by deliberately directing the blade to the right paraglos­ sal space. 24 When correctly positioned, the proximal portion of the blade is lateral to the right of the patient's right nostril and no tongue is present to the right of the blade. Insertion of the blade should occur through the right lateral mouth over the molar dentition. The distal blade may then be directed medi­ ally, although the proximal blade should never be brought back toward the midline upper incisors. With a curved blade, the large reverse Z-shaped flange allows tongue sweeping. To avoid the thick chest or breasts, particu­ larly in patients with a short neck, many practitioners prefer to insert the blade with the handle tilted sideways toward the right and insert the blade into the mouth at a slight right lateral position. A potential problem with this approach is that the epiglottis and the larynx are then approached "off angle" and depending upon the depth of insertion this can create landmark confusion. The aryepiglottic fold can be misinterpreted as the epiglottis edge, and if inserted too deeply, the tip of the blade will pass under the posterior cartilages into the esophagus. With the patient's face plane parallel to the ceiling, the author prefers to follow the curve of the blade down the curve of tongue, slightly to the right of midline, with early compression/ lift of the tongue as necessary to visualize the epiglottis edge. In this first stage of laryngoscopy, only a gentle force is required to distract the jaw caudad, lifting the epiglottis edge off the posterior pharyngeal wall. The direction of the handle upon insertion and with initial jaw distraction is toward the patient's feet, and at a very shallow angle as the blade is advanced down the tongue (perhaps only approximately 20 degrees up from horizontal) . Inexperienced users will commonly place the blade tip too far, before looking for landmarks. This is particularly common when using a longer blade (e.g., #4 Macintosh blade) . After the epiglottis has been recognized, and before the blade is engaged with greater force, the practitioner should check tongue position and move the blade rightward as necessary to effectively control the tongue. In practice, epiglottoscopy and tongue control happen simultaneously.

structures, and the first visible under the epiglottis edge, are the interarytenoid notch and the accompanying right and left arytenoids cartilages. Above the interarytenoid notch, and just medial to the arytenoid cartilages, is the posterior aspect of the glottic opening. Moving more anteriorly, the aryepiglottic folds are visible laterally, and the true and false vocal cords medially. Finally, most anterior and farthest within the laryngeal inlet is the anterior commissure of the vocal cords. • What Are the Subtleties of Curved Blade

Laryngoscopy, and What Is Bimanual Laryngoscopy?

The effectiveness of indirect epiglottis elevation hinges on proper placement of the blade tip in the vallecula as well as cor­ rectly directing force down the blade. Following epiglottoscopy, the tip of the blade needs to be fully advanced into the vallecula and the lifting force increased compared to what was needed for distracting the jaw and visualizing the epiglottis. The force direction is along the forearm and down the blade, in a man­ ner that the practitioner's arm and forearm are extended away from the torso. The handle should not be tilted backwards, otherwise the tip of the blade will come out of the vallecula and there will be inadequate pressure on the underlying hyoepiglot­ tic ligament. With the force directed down the blade (i.e., the force vector approximately perpendicular to the practitioner) , the tip of the blade can be effectively driven into the vallecula and resulting pressure on the hyoepiglottic ligament will cause the epiglottis to indirectly elevate (Figure 9- 1 0) . I f the tip o f the blade is not fully seated into the vallecula "engaging" the hyoepiglottic ligament, no amount of lifting force will correctly elevate the epiglottis. A difference in blade tip placement of millimeters will affect the degree of epiglottic control This is likely one of the primary reasons for skill/expe­ rienced-based variations in the laryngoscopic views. One way to seat the blade tip correctly is by performing bimanual laryn­ goscopy.46 The practitioner uses their free right hand to reach

• How Can Direct Laryngoscopy be Made

More Pred ictable and Not a "Hit or Miss" Proced ure?

From insertion of the blade until visualization of the larynx, there is a predictable, sequential exposure of landmarks that results from progressive advancement of the LOS . As a laryn­ goscope blade is advanced over and down the surface of the tongue, into the pharynx and then the hypopharynx, the LOS moves from the uvula, to the posterior pharynx, and then at the base of the tongue, to the epiglottis. With the curved blade, the epiglottis is indirectly elevated, while with the straight blade the epiglottis is directly lifted. Once the epiglottis is visualized, the practitioner knows where the larynx will be located. Effective epiglottis control (either indirectly with a curved blade, or directly with a straight blade) will then permit progressive exposure of laryngeal landmarks. The structures of the larynx become visible from the most posterior to the most anterior. The most posterior laryngeal

F I G U R E 9-1 0. Di rect l a ryngoscopy with a cu rved Ma c i ntosh l a ryngoscope in a sagg ita l section of a cadave r: the t i p of the b l a d e s h o u l d be p l a ced i nto the va l l e c u l a a n d the resu lt i n g pres s u re on the hyoe p i g l ottic l ig a m ent (a rrow) wi l l cause the epig l otti s to i n d i rectly el evate.

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around to the anterior neck of the patient and apply external manipulation to the thyroid cartilage with a downward (back­ ward, posterior) force. The tip of the blade is like a key being inserted into the lock of the vallecula. Bimanual laryngoscopy serves to fully insert the key all the way into the lock, which only then will allow turning (elevating the epiglottis) and "opening" the lar­ ynx. In some cases, bimanual larynoscopy may be best at the cricoid cartilage, or even the hyoid, although Benumof and Cooper27found that optimal manipulation was at the thyroid cartilage in almost 90% of cases. The practitioner need not be concerned about the exact position of their right hand. There is instantaneous visual feedback about the effectiveness of epiglot­ tis elevation, and it is easy to move the right hand slightly up or down on the patient's neck to optimize the view. Bimanual laryngoscopy improves laryngeal view in two ways. First, it changes the mechanics as described, correctly sitting the blade tip where it needs to be. Second, it helps to move the larynx downward (backward) into the practitioner's LOS . The mobility of the larynx and the ability of the prac­ titioner to move it backward into view during the procedure were something known even to Czermark in the mid- 1 9th century, when mirror laryngoscopy was first developed. Early wood block prints of Czermark performing mirror laryngos­ copy show one hand on the patient's neck while his other hand holds the mirror within the mouth. 2 A critical component of bimanual laryngoscopy is the direct practitioner connection between neck manipulation and the immediately observed effect on laryngeal view. Cricoid pressure (discussed below) and Backward Upward Rightward Pressure (BURP28) involve an assistant applying pressure to the neck. Given the subtlety of laryngoscopy, and that minor changes in blade tip position or force can significantly alter exposure and epiglottis control, bimanual laryngoscopy performed by the prac­ titioner (referred by some as optimal external laryngeal manipula­ tion, OELM) is the most effective means of optimizing laryngeal view. 27 An assistant can be taught to maintain pressure at this loca­ tion, while the practitioner uses the right hand to pass the ETT. The term "bimanual laryngoscopy" has also been used to describe a technique where the left hand manipulates the laryn­ goscope while the right hand is placed behind the occiput to manipulate the head and neck position to obtain the best view of the glottis. • How Is Optimal External Laryngeal

Manipu lation Different than Cricoid Pressure (the "Sellick Maneuver")? Can Cricoid Pressu re and OELM be Used Together (see also section "Cricoid Pressu re" in Chapter 5)?

In 1 96 1 , Sellick described backward pressure on the cricoid ring by an assistant as a method of preventing passive regurgi­ tation of stomach contents during elective anesthesia.44 It has become a standard part of emergency laryngoscopy and RSI. It seems logical that pressure on the cricoid could occlude the esophagus and that this is advantageous in full stomach or aspi­ ration risk patients.

It is critical for airway practitioners to evaluate recent evi­ dence regarding cricoid pressure and whether it should be a standard part of emergency laryngoscopy for two reasons (see a detailed discussion in Chapter 5). First, imaging of the neck with computed tomography and magnetic resonance imaging (MRI) by Smith et al.47,48 has established that the mechanics are not what they seem. Total occlusion of the esophagus does not occur in 9 1 % of patients when cricoid pressure is applied because the esophagus is actually not midline, immediately behind the cricoid cartilage, but laterally displaced. However, Smith did find that the lumen of the esophagus was signifi­ cantly compressed even if displaced laterally. In a study with awake adult volunteers using MRI, Rice et al.49 found that the mean anteroposterior diameter of the hypopharynx was reduced by 35% and the lumen likely obliterated with cricoid pressure, and this compression was maintained even when the cricoid ring was lateral to the vertebral body. These findings suggest that the location of the esophagus is irrelevant to the efficacy of the cricoid pressure with regard to the prevention of gastric regurgitation into the pharynx and that there is no reason to suggest that traditional practice be abandoned. The second reason why cricoid pressure should be examined critically is that the parameters of ventilation and positioning have changed dramatically from when Sellick conceived his technique. In Sellick's time, ventilation volumes averaged 1 0 to 1 5 mL-kg- 1 and ventilation rates were 1 2 to 1 5 o r more breaths per minute. Current practice is to use much smaller ventilation volumes, only 6 to 7 mLkg- \ and higher ventila­ tion rates to reduce the risk of exceeding esophageal opening pressure (25 - 30 em H 0) , yet again reducing the risk of gas­ 2 tric insuffiation and regurgitation. Sellick believed cricoid pressure would only work if the head and neck were placed in hyperextension in order to pin the esophagus between the cricoid and the vertebrae.44 He further advocated that the head be in a head down position. Should any regurgitation recur, the material could drain out and not into the lungs.44 This hyperextended head and neck position, and positioning the head down are antithetical to what we now know is optimal for effective ventilation and maximizing upper airway patency. Laryngeal manipulation (BURP or bimanual laryngoscopy) should not be confused with cricoid pressure. Cricoid pressure is usually done by an assistant rather than the practitioner and it is not primarily intended to improve laryngeal exposure. It is also applied lower on the neck than laryngeal manipula­ tion. If initiated upon induction (before blade insertion) , cri­ coid pressure may prevent the blade tip from being correctly seated in the vallecula. Recent evidence has identified that the application of cricoid pressure may increase the incidence of a difficult emergency laryngoscopy (grade 3 or 4 Cormack/ Lehane view) . A growing body of literature has highlighted the detrimental effects of cricoid pressure on laryngoscopy, mask­ ventilation, and LMA placement although it has yet to dem­ onstrate increased problem with gas exchange or intubation failure rates.50'5 1 I n summary, i t seems reasonable t o continue with the prac­ tice of applying cricoid pressure (Sellick's maneuver) at least until the evidence demonstrates that it is futile at preventing

Di rect La ryng oscopy

aspiration or leads to increased gas exchange and intubation failure rates. • Apart from Paraglossa l Placement, What

Are the Specifics of Correctly Perform ing Straight Blade Laryngoscopy?

Much of the specifics of straight blade laryngoscopy have already been discussed, that is, paraglossal placement, and use of the extreme right corner of the mouth for blade positioning, tilting, and tube delivery. There is a critical aspect of straight blade laryngoscopy that needs to be addressed, however, and that is the direct lifting of the epiglottis. After the epiglottis edge is identified, the handle must be tilted forward (e.g. , the tip backward, toward the posterior hypo­ pharynx) , the blade inserted slightly (approximately 1 -2 em) , and the tip passed under the epiglottis. Once the epiglottis is "trapped" under the blade tip, the blade is rocked slightly backward (handle brought slightly more upright) and then the lifting force increased. Jackson described the lifting direction as suspending the patient's head with the flat section of the blade, at a point underneath the hyoid bone. 2 Miller blades have an upturned distal tip that varies among manufacturers. This renders the distal blade tip invisible to the practitioner when viewed down the long axis of the blade. A potential problem with this design is that the practitioner does not know if the blade has been advanced far enough to trap the epiglottis until the blade is rocked backward; frequently the tip of the epiglottis is not trapped and the advancement and tilting maneuver needs to be repeated. The Henderson blade is a novel straight blade design that has a deliberately visible distal tip. Underneath, within the barrel of the distal tip is a knurled edge that is easily seen when the prac­ titioner looks down the blade (Figure 9-5) . This allows the practitioner to place the tip under the epiglottis and know with certainty that the epiglottis is trapped. OELM is helpful with straight blades because the posterior laryngeal pressure displaces the target into view. • I n Addition to OELM, What Other Maneuvers

Can be Done During La ryngoscopy to Improve a Poor Laryngeal View?

Practitioners should understand and be ready to respond to poor laryngeal view within their first laryngoscopy attempt. There should be a specific planned approached to find the epiglottis and optimize blade tip position. In addition to OELM, and making sure the curved tip is driven fully into the vallecula, another technique for improving an epiglottis-only view is to dynamically lift the patient's head higher. This technique, which the author has called "Head Elevated Laryngoscopy Positioning" (HELP, and others have called "bimanual laryn­ goscopy"), was first described by Richard Johnston5 2 in 1 909, and later adopted by Jackson and included in his subsequent textbooks . 1 '2 As already noted, head elevation permits greater jaw distraction because of its mechanically favorable effect on mouth opening. It enlarges the area beneath the base of the tongue and epiglottis improving visualization. According

to Jackson, exaggerated head elevation also better aligned the blade axis with the axis of the upper trachea and larynx. The practitioner can perform head elevation by using their right hand to lift the patient's occiput. Alternatively, some prac­ titioners have used their abdomen to lean forward and prop up and elevate the patient's head. Alternatively, an assistant can easily help by using two hands to lift the head from the patient's side. In the morbidly obese, dynamic lifting is often not feasible given the weight involved. A large ramp is needed extending from under the occiput, to the upper shoulders which then tapers to the mid-low back, in order to provide proper position­ ing (see Figure 20-2) . An inflatable ramp has been designed for this purpose for airway management in the morbidly obese called the Rapid Airway Management Positioner. 53 A noninflat­ able version is called the Troop Pillow (see Figure 5 1 -2) . Regardless of which lifting technique is used, the patient's stretcher height must be kept low enough to permit head eleva­ tion and yet still provide a good perspective for the practitioner to look down the mouth into a patient whose face plane is parallel to the ceiling. For some practitioners, especially when dealing with larger patients, this may require a footstool for the practitioner to be at proper height. • What Are the Most Common Errors of Direct

Laryngoscopy by Novices?

The three most common errors that novice practitioners make during laryngoscopy include: 1 . Placing the blade too deep before looking (not performing epiglottoscopy) 2. Entering the vallecula and lifting without engaging the hyo­ epiglottic ligament 3. Not using their right hand (bimanual laryngoscopy, OELM, BURP, HELP) to optimize the view Novice practitioners move right past the epiglottis, insert the blade tip too deep, and then cannot recognize any laryngeal structures. They typically try to transfer their practice experi­ ence from an intubation trainer to an actual patient and find recognition of structures very difficult. This occurs because of unrecognized visual restrictions, epiglottis camouflage, and little understanding of the nuances of laryngeal anatomy. They also do not appreciate how minor manipulative adjustments of the blade tip affect laryngeal exposure, instead resorting to extra lifting effort. Their response to a poor laryngeal view is to move the blade in and out with large movements, leading to edema, tissue trauma, bleeding, and possibly perforation of the upper esophagus or hypopharynx. The best way to avoid landmark confusion is to be meticulous about epiglottoscopy. Novice practitioners should carefully study video imaging of DL prior to practicing on real patients paying particular attention to the nuances of anatomy and technique. The visual restrictions inherent to laryngoscopy make targeted feedback and supervision during the procedure impossible. With inten­ sive video training, novice intubators can achieve a 90% success rate on their first ten attempts, while initial success rates with standard mannequin only training are low (50%) ? Following mannequin-only practice, a statistical modeling showed that

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the number of laryngoscopic intubations required to achieve a 90o/o success rate in anesthetized patients with a normal airway in an operating room environment was 47.55 • Are There Specific Patients, Apart from Small

Children, in Whom Curved Blades Perform Poorly or in Whom a Straight Blade Would be the First Choice?

Patients who have lingual tonsillar hyperplasia have excess tissue at the base of the tongue and a small or nonexistent val­ lecula, making indirect epiglottis elevation very difficult. This is a rare condition, but can lead to unexpected failed laryn­ goscopy, since the base of tongue and epiglottis are not visible to oral examination during pre-procedural assessment. There are case reports of such patients being able to be intubated using a paraglossal straight blade technique.56 If the condi­ tion was known in advance, it would be prudent to avoid DL altogether since it could prevent laryngeal exposure with a laryngoscope and also lead to very difficult mask and LMA ventilation. Patients with large central dental gaps may be more easily intubated using a straight blade, since the large flange on the curved blade may lock into the gap creating a very restricted space for tube delivery. In such instances, ETI can be very help­ ful, or alternatively, a straight blade can be used with a paraglos­ sal approach.

E N DOTRACH EAL TU B E PLACEMENT

causing the tube to contact the sides of the mouth, tongue, and teeth. As efforts are made to direct the tip upward, for example, the mid-section of the tube will contact the teeth when used with a stylet, causing bending of the mid-section of the tube and stylet. The other problem with an arcuate­ shaped tube (and stylet) is that minor rotational change will cause the distal tip to move substantially. When this occurs at the last moment of insertion toward the target, the mid­ section of the tube may visually block the target itself, lead­ ing to inadvertent and unseen passage of the tube into the esophagus . A straight-to-cuff shaped tube and stylet has a narrow long axis and offers significant visual advantages than a tube alone, or a tube with an arcuate-shaped stylet.9•57 When viewed down the long axis it has a very narrow dimension. It can be passed into the mouth and easily maneuvered without obscuring the target as it advanced toward the target. The ideal method of inserting an ETT is to always pass the tube from beneath the LOS and bring the distal tube tip up from below, passing over the interarytenoid notch under direct vision without obscuring the target itself Many practitioners prefer using a styletted tube for all tracheal intubations because of this maneuverability and visualization advantage. When the tube is first inserted in the extreme right corner of the mouth, the tube is placed visually behind the maxilla, and the distal tip is not even seen. By rock­ ing the proximal tube backward, the distal tip moves posteriorly from behind the maxilla, up into the LOS, and anteriorly until it is placed above the posterior landmarks of the larynx and into the trachea.

• Tu be Delivery Is a Sepa rate and Distinct

• Where Exactly Should the Styletted

Polyvinyl chloride (PVC) ETTs have a gentle arcuate shape, as prescribed by American Society of Testing of Materials stan­ dards. The standard tube also has an asymmetric tip, with the bevel of the tube facing leftward when viewed from the practi­ tioner's perspective ("Magill bevel") , down the long axis of the tube, as the tube is inserted into a patient. The optical challenges of DL have already been described. When there is favorable laryngeal exposure, tube delivery is rarely problematic. Conversely, when only a small portion of the glottic opening is visible, or even just the interarytenoid notch can be seen, tube delivery may obscure simultaneous visualization of the target. All instruments designed to be passed into narrow body cav­ ities have a narrow long-axis dimension and an upward distal turn. Instruments that adhere to this shape are alligator forceps, laryngeal mirrors, and ETI . The optical benefit of this shape is that the long straight section allows good maneuverability toward a target, while the upturned distal tip makes the tip of the device visible. The large curvature of standard PVC ETTs (or those pre­ packaged with a matching arcuate-shaped stylet) is difficult to maneuver in the mouth and hypopharynx. They have a wide side-to-side dimension when viewed down the long axis,

The historic approach to stylet shaping is to use a "hockey stick." But this neither defines the optimal bending point nor the proper angle. A more precise terminology is to use the term "straight-to-cufF' stylet shaping, followed by an angle not exceeding 35 degrees to the tube tip.46 This narrow long­ axis shape is ideal for tube delivery toward the glottis, without blocking the LOS . It still provides enough of a bend upward allowing the distal tube tip to be easily seen. The bend point should be at the proximal end of the cuff and the stylet should stop at the distal end of the cuff. The stylet can be dangerous if it protrudes beyond the tube tip. It can cause the tip to be too stiff even if it extends just to the tip of the tube. By stopping the stylet tip at the distal cuff, it provides an effective bend without stiffening the tip of the tube. Angles beyond 35 degrees confer no visual advantage and hinder maneuverability within the mouth and hypopharynx. After the tip has passed into the trachea, bend angles above 35 degrees cause the tip of the tube to impact on the anterior tracheal rings.46 This phenomenon explains why it is possible to have a correctly sized tube between the vocal cords and be unable to pass the tube, even though the trachea itself is large enough to accept it.

Challenge from La ryngeal Exposu re. What Is the Role for Stylets, Tu be I ntrod ucers, and Optical Stylets?

Tube be Bent, and What Is the Appropriate Angle to Use to Maximize Tip Visualization, But Not Mecha nical ly Affect Insertion?

Di rect La ryng oscopy

• What Should the Practitioner Do If the Tube

Tip Catches in the Cricothyroid Space or on the Tracheal Rings after Insertion?

One option is to withdraw the stylet without withdrawing the tube itself. An assistant is necessary to do this since the practi­ tioner will be holding the laryngoscope in their left hand and the tube in their right hand. By reducing the stiffness of the distal tube it may then be able to advance into the trachea. This maneuver, however, can easily result in dislodgement of the tube with resultant esophageal intubation on advancement. Another option to rectifY this mechanical hang-up on the anterior tracheal wall is to rotate the tube clockwise if resistance is felt. By turning the tube 90 degrees clockwise, the standard left-facing bevel of the ETT moves from facing leftward to fac­ ing upward. The leading edge of the tube rotates downward, away from the rings by this movement, and it disengages.9 If time permits, Hung et al.58 suggested the combination of softening of the ETT by immersing the ETT in warm saline solution and reverse loading of the ETT onto the stylet may potentially overcome the problems with the "hang up" during intubation. With the reverse loading, the tip of the ETT is more likely to be directed down the trajectory of the trachea during the retraction of the stylet, making it easier to advance. • What Are the Options for an

Epiglottis-Only View?

Assuming every effort has been made to maxtmtze laryngeal view with the laryngoscope, there are several options for intuba­ tion. The first of these is to hug the undersurface of the epiglot­ tis with the straight-to-cuff styletted tube, and being mindful of the tip orientation (keeping it upright) , to insert the tube blindly. In general, blind insertion should be avoided. An ETI can be used for intubation in epiglottis-only views. Newer disposable tracheal tube introducers are inexpensive. When compared with the use of a stylet in simulated Cormack! Lehane grade 3 views, the success rates using this device is as high as 96% with the ETI and 66% using a stylet. 59 In the true epiglottis only view, the tip of the ETI is directed upward hugging the undersurface of the epiglottis. Practitioners should be aware that minor rotational change will cause the tip to move lateral to the aryepiglottic fold (missing the larynx) . The ETI is approximately 60-cm long, straight over its entire length, except for its distal end, which has a slight upward bend (Coude tip) . The original Portex product (made of resin cov­ ered fiberglass) has a bend angle of 38 degrees and this angle has been copied in the many disposable tracheal introducers now produced. After the tracheal introducer has passed into the trachea, the anterior tracheal rings may be felt (clicks) as the rounded tip passes over them. This occurs in 60% to 95% of cases, but it is practitioner and situation dependent, and also a function of the orientation of the distal tip. If the tip rotates downward after insertion, the tip will ride along the posterior membraneous portion of the trachea and not pass over the rings (i.e., no tactile feedback of tracheal placement) . In the trachea, as the tip passes beyond the mainstem bronchus, the narrowing diameter will cause it to stop between 30 and 35 centimeters. This distinct endpoint is more reliable in assessing tracheal

placement. On reaching this endpoint, the tracheal introducer should be pulled back by 2 to 3 em. When the tracheal intro­ ducer is placed into the esophagus, no rings are felt, and there should be no limit to advancement. After tracheal introducer placement, the ETT is placed over the proximally stabilized tracheal introducer (by an assistant) and slide down ("railroaded") its length into the mouth and ultimately the trachea. The laryngoscope should be maintained in the same position as was achieved during the initial laryngos­ copy attempt. This promotes a long-axis slide of the ETT over the tracheal introducer. Without the laryngoscope, the tracheal introducer will bend in the pharynx and be surrounded by adja­ cent soft tissues that can cause difficulties with tube advance­ ment. The beveled leading edge of the larger diameter ETT can "holdup" at the laryngeal inlet (right aryepiglottic fold, right arytenoid cartilage, or right vocal cord) as the tube is advanced over the tracheal introducer. This can be avoided by using a smaller ETT. This holdup is easily managed by turning (quarter turn) the ETT counter clockwise as it approaches the laryngeal inlet. This maneuver positions the bevel facing inferiorly allow­ ing uninhibited passage into the trachea. It is important to note that there is major difference between the Cormack/Lehane grade 3A and 3B-the latter being the sit­ uation where the epiglottis is visible but lies against the posterior hypopharyngeal wall. In this situation the tracheal introducer is not stiff enough to lift the epiglottis and it becomes more dif­ ficult to direct it into the glottis. The true incidence of this view is not known, and as stated earlier, may relate to improper blade tip placement deflecting the epiglottis posteriorly. A more effective means for approaching the epiglottis-only view for practioners who have acquired the skill is to use a mal­ leable optical stylet.46 This permits target visualization either through an eyepiece or a monitor and the stylet tip can be advance under indirect vision into the trachea. These devices require significant handling experience and recognition of fiberoptic landmarks and are addressed in Chapter 1 1 .

S U M MARY Placement of a tracheal tube under direct vision using a laryn­ goscope remains one of the most important skills to master for all airway practitioners. Many types of laryngoscopes with curve and straight blades have been development over the years with the objectives to improve visualization of the glottis and easy passage of the tracheal tube. While these devices are highly effective and safe, they all have limitations. To improve out­ come and minimize the risk of complications, basic principles and techniques must be applied when performing a laryngo­ scopic intubation.

REFERENCES I . Zeitels SM. Universal modular glottiscope system: the evolution of a cen­ tury of design and technique for direct laryngoscopy. Ann Otol Rhino! Laryngol Suppl. 1 999; 1 79:2-24. 2. Jackson C. Bronchoscopy and Esophagoscopy. A Manual ofPeroral Endoscopy and Laryngeal Surgery. Philadelphia, PA: W B . Saunders; 1 922. 3 . Magill IW Technique in Endotracheal Anaesthesia. Br Med ]. 1 930; 2:8 1 7-8 1 9.

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Ai rway Tec h n i q ues 4. Miller RA . A new laryngoscope. Anesthesiology. 1 94 1 ;2:3 1 8-320. 5 . Macintosh RR. A new laryngoscope. Lancet. 1 943; 1 :20 5 . 6. Delport SD, Gibson BH. Ingestion of a laryngoscope light bulb during tracheal intubation. S Afr Medj. 1 992; 8 1 :579. 7. Naumovski L, Schaffer K, Fleisher B. Ingestion of a laryngoscope light bulb during delivery room resuscitation. Pediatrics. 1 99 1 ;87: 5 8 1 -582. 8. Cheung KW, Kovacs G, Law JA, Brousseau P, Hill W. Illumination of bulb-on-blade laryngoscopes in the out-of-hospital setting. Acad Emerg Med. 2007; 14:496-499. 9. Levitan RM , Kinkle WC. 1he Airway Cam Pocket Guide to Intubation. 2nd ed. Wayne PA: Airway Cam Technologies, Inc. ; 2007. 10. Lighting for Hospitals and Health Care Facilities. http://www.techstreet. com/cgi-bin/detail?product_id= 1 1 890. Accessed June 6, 20 1 0 . 1 1 . International Organization for Standardization. Anesthetic and Respira­ tory Equipment-Laryngo-Scopes for Tracheal Intubation. ISO 7376 TC 1 2 l;SC 2, N8 1 3, September. Geneva: ISO, 200 5 . 1 2 . Chisholm D G , Calder I. Experience with the McCoy laryngoscope i n dif­ ficult laryngoscopy. Anaesthesia. 1 997;52: 906-908. 13. Haridas RP. The McCoy levering laryngoscope blade. Anaesthesia. 1 996; 5 1 : 9 1 . 14. Johnston H M , Rao U . Th e McCoy levering laryngoscope blade. Anaesthesia. 1 994;49 : 3 5 8 . 1 5 . Laurent S C , d e Melo AE, Alexander-Williams J M . The use of the McCoy laryngoscope in patients with simulated cervical spine inj uries. Anaesthesia. 1 996; 5 1 :74-75. 1 6. Uchida T, Hikawa Y, Saito Y, Yasuda K. The McCoy levering laryngoscope in patients with limited neck extension. Can } Anaesth. 1 997;44:674-676. 1 7. Ward M. The McCoy levering laryngoscope blade. Anaesthesia. 1 994; 49:357-358. 18. Gerlach K, Wenzel V, von Knobelsdorff G, Steinfath M, Dorges V. A new universal laryngoscope blade: a preliminary comparison with Macintosh laryngoscope blades. Resuscitation. 2003;57:63-67. 1 9. Kelley MA, Boskovich S, Allegretti PJ. Laryngoscope blade review. Am j Emerg Med. 2008;26:9 52-9 5 5 . 2 0 . Levitan RM , Mechem CC, Ochroch EA, Shafer FS, Hollander J E . Head­ elevated laryngoscopy position: improving laryngeal exposure during laryn­ goscopy by increasing head elevation. Ann Emerg Med. 2003;41 :322-330. 2 1 . Crosby ET. Airway management in adults after cervical spine trauma. Anesthesiology. 2006; 1 04: 1 293- 1 3 1 8 . 22. Manoach S, Paladino L. Manual in-line stabilization for acute airway man­ agement of suspected cervical spine injury: historical review and current questions. Ann Emerg Med. 2007; 50:236-24 5 . 23. Manoach S, Paladino L. Laryngoscopy force, visualization, and intubation failure in acute trauma: should we modifY the practice of manual in-line stabilization? Anesthesiology. 2009; 1 1 0: 6-7. 24. Henderson JJ. The use of paraglossal straight blade laryngoscopy in dif­ ficult tracheal intubation. Anaesthesia. 1 997;52:5 52-560. 25. Heath KJ. The effect of laryngoscopy of different cervical spine immobili­ sation techniques. Anaesthesia. 1 994;49: 843-845. 26. Robitaille A, Williams SR, Tremblay MH, Guilbert F, Theriault M, Drolet P. Cervical spine motion during tracheal intubation with manual in-line stabilization: direct laryngoscopy versus GlideScope videolaryngoscopy. Anesth Analg. 2008; 1 06: 935-94 1 . 27. BenumofJL, Cooper SD. Quantitative improvement in laryngoscopic view by optimal external laryngeal manipulation. } Clin Anesth. 1 996;8: 1 36- 1 40. 28. Knill RL. Difficult laryngoscopy made easy with a "BURP". Can JAnaesth. 1 993;40:279-282. 29. Levitan RM , Higgins MS, Ochroch EA. Contrary to popular belief and traditional instruction, the larynx is sighted one eye at a time during direct laryngoscopy. Acad Emerg Med. 1 99 8 ; 5 : 844-846. 30. Yentis SM. Predicting difficult intubation--worthwhile exercise or pointless ritual? Anaesthesia. 2002;57: 1 0 5- 1 09. 3 1 . Shiga T, Waj ima Z, Inoue T, Sakamoto A. Predicting difficult intubation in apparently normal patients: a meta-analysis of bedside screening test performance. Anesthesiology. 2005 ; 1 03:429-437. 32. Mort TC. Emergency tracheal intubation: complications associated with repeated laryngoscopic attempts. Anesth Analg. 2004;99: 607-6 1 3 , table of contents. 33. Cormack RS, Lehane J. Difficult tracheal intubation in obstetrics. Anaesthesia. 1 984;39: 1 1 05 - 1 1 1 1 . 34. Cook TM. A new practical classification of laryngeal view. Anaesthesia. 2000; 5 5 :274-279. 3 5 . Ochroch EA, Hollander JE, Kush S, Shafer FS, Levitan RM . Assessment of laryngeal view: percentage of glottic opening score vs Cormack and Lehane grading. Can } Anaesth. 1 999;46:987-990. 36. Adnet F, Barron SW, Racine SX, et al. The intubation difficulty scale (IDS) : proposal and evaluation of a new score characterizing the complex­ ity of endotracheal intubation. Anesthesiology. 1 997;87 : 1 290- 1 297.

37. Benumof JL. Difficult laryngoscopy: obtaining the best view. Can } Anaesth. 1 994;4 1 :3 6 1 -365. 38. Boyce JR, Ness T, Castroman P, Gleysteen JJ. A preliminary study of the optimal anesthesia positioning for the morbidly obese patient. Obes Surg. 2003; 1 3:4-9. 39. Dixon BJ, Dixon JB, Carden JR, et a!. Preoxygenation is more effec­ tive in the 25 degrees head-up position than in the supine position in severely obese patients: a randomized controlled study. Anesthesiology. 2005 ; 1 02: 1 1 1 0- 1 1 1 5; discussion SA. 40. Lane S, Saunders D, Schofield A, Padmanabhan R, Hildreth A, Laws D. A prospective, randomised controlled trial comparing the efficacy of pre­ oxygenation in the 20 degrees head-up vs supine position. Anaesthesia. 2005;60: 1 064- 1 067. 4 1 . Benumof JL. Preoxygenation: best method for both efficacy and efficiency. Anesthesiology. 1 999;9 1 : 603-605 . 4 2 . Benumof JL, Dagg R , Benumof R . Critical hemoglobin desaturation will occur before return to an unparalyzed state following 1 mg/kg intravenous succinylcholine. Anesthesiology. 1 997;87:979-982. 43. Mort TC. Preoxygenation in critically ill patients requiring emergency tra­ cheal intubation. Crit Care Med. 2005;33:2672-2675 . 44. Sellick BA. Cricoid pressure t o control regurgitation of stomach contents during induction of anaesthesia. Lancet. 1 9 6 1 ;2:404-406. 45. Satiani B, Bonner JT, Stone HH. Factors influencing intraoperative gastric regurgitation: a prospective random study of nasogastric tube drainage. Arch Surg. 1 978; 1 1 3:72 1 -723. 46. Levitan RM . Design rationale and intended use of a short optical stylet for routine fiberoptic augmentation of emergency laryngoscopy. Am J Emerg Med. 2006;24:490-495. 47. Smith KJ, Dobranowski J, Yip G, Dauphin A, Choi PT. Cricoid pressure displaces the esophagus: an observational study using magnetic resonance imaging. Anesthesiology. 2003;99: 60-64. 48. Smith KJ, Ladak S, Choi PT, Dobranowski J. The cricoid cartilage and the esophagus are not aligned in close to half of adult patients. Can J Anaesth. 2002;49 : 5 03-507. 49. Rice MJ, Mancuso AA, Gibbs C, Morey TE, Gravenstein N, Deitte LA. Cricoid pressure results in compression of the postcricoid hypopharynx: the esophageal position is irrelevant. Anesth Analg. 2009; 1 09: 1 546- 1 552. SO. Ellis DY, Harris T, Zideman D. Cricoid pressure in emergency department rapid sequence tracheal intubations: a risk-benefit analysis. Ann Emerg Med. 2007; 50:653-665. 5 1 . Neilipovitz DT, Crosby ET. No evidence for decreased incidence of aspira­ tion after rapid sequence induction. Can } Anaesth. 2007; 54:748-764. 52. Johnston RH. Extension and flexion in direct laryngoscopy: A comparative study. Ann Oto Rhino Laryn. 1 9 1 0 ; 1 9: 1 9-24. 53. Carrano D, Melnikov V, Khalil Y, Sridhar S, Hagberg CA. An evalua­ tion of the rapid airway management positioner in obese patients under­ going gastric bypass or laparoscopic gastric banding surgery. Obes Surg. 20 1 0;20: 1 436- 1 44 1 . 54. Levitan RM , Goldman TS, Bryan DA, Shafer F, Herlich A. Training with video imaging improves the initial intubation success rates of paramedic trainees in an operating room setting. Ann Emerg Med. 200 1 ;37:46-50. 5 5 . Mulcaster JT, Mills J, Hung OR, et al. Laryngoscopic intubation: learning and performance. Anesthesiology. 2003;98:23-27. 56. Ovassapian A, Glassenberg R, Randel Gl, Klock A, Mesnick PS, Klafta JM. The unexpected difficult airway and lingual tonsil hyperplasia: a case series and a review of the literature. Anesthesiology. 2002;97: 1 24- 1 32. 57. Levitan RM . 1he Airway Cam Guide to Intubation and Practical Emergency Airway Management. Wayne PA: Airway Cam Technologies, Inc.; 2004. 58. Hung OR, Tibbet JS, Cheng R, Law JA. Proper preparation of the Trachlight and endotracheal tube to facilitate intubation. Can } Anaesth. 2006; 5 3 : 1 07- 1 08. 59. Gataure PS, Vaughan RS, Latta IP. Simulated difficult intubation. Comparison of the gum elastic bougie and the stylet. Anaesthesia. 1 996; 5 1 :935-938.

SELF - EVALUATION QU ESTIONS 9 . 1 . Regarding the mechanics o f laryngoscopy all are true

EXCEPT A. A fully extended arm position permits binocular sight­ ing of the larynx for most operators B. A low grip, that is, where the blade meets the handle, provides greater control with less muscular effort

Di rect La ryng oscopy

C. Morbidly obese patients require proper ear-to-sternal notch positioning before laryngoscope insertion, since dynamic lifting of the head during the procedure is impossible D. The degree of lifting force applied during laryngoscopy is minimal when advancing the curved blade down the tongue and maximal after the blade is correctly posi­ tioned in the vallecula 9.2. Bimanual laryngoscopy is A. distinct from cricoid pressure because is applied by the laryngoscopist B. distinct from cricoid pressure because it is done to improve laryngeal view C. distinct from Backward Upward Rightward Pressure (BURP) because it is done by the operator, not an assistant

D. distinct from cricoid pressure because it is generally applied at the thyroid cartilage, not the cricoid ring E. All of the above 9 . 3 . The mechanical problem rail-roading an endotracheal tube over a tube introducer (or a flexible fiberscope) A.

can be overcome by rotating the tracheal tube counter­ clockwise (leftward) 90 degrees at 14 to 1 6 em of insertion

B. is a consequence of the asymmetric left-facing bevel of a standard tracheal tube C. is due to the gap between the outer diameter of the introducer (or scope) and the inner diameter of the tracheal tube D. occurs at the laryngeal inlet, specifically at the right aryepiglottic fold and right posterior cartilages E. all of the above

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C H A PT E R 1 0

F lexib le Bron choscopic Intubation Jan R. Morris

CASE PRESENTATION . . .

1 72

I NTRO DUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1 72

EQUI PMENT .

1 74

TECH N I Q U E

1 77

OTH ER TECH N I Q U ES A N D ADJ U NCTS TO FAC I LITATE BRONCHOSCO P I C I NTU BATION . .

1 83

UTI LIZATI O N OF B RONCHOSCO P I C I NTU BATION I N D I F FERENT S ETIINGS

1 86

OTH ER CO N S I D ERATIONS . . . . . . . . . . . . . . . . . . . . . . .

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S U MMARY . . . . . . . . . . . .

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SELF-EVALUATIO N Q U ESTI O N S . . . . . . . . . . . . . . . . . . . 1 97

CASE PRESENTATION A 65-year-old male with carcinoma of the colon presents for colon resection. He weighs 120 kg and is 1 57 em tall (BMI 48 kg·m- 2) . He has a history of hypertension and obstructive sleep apnea. On airway examination, he has a Mallampati IV score; 3-cm mouth opening, a large tongue, full dentition, about 0.5 em of mandibular protrusion, a receding mandible, decreased cervical spine extension, and has a short thick neck. His crico­ thyroid membrane is difficult to palpate. He has predictors of difficult direct laryngoscopy, difficult video-laryngoscopy, dif­ ficult bag-mask-ventilation, difficult extraglottic device (EGO) use, and a difficult surgical airway. He is likely to be intolerant of apnea. An awake bronchoscopic intubation was performed which was uneventful as was his subsequent surgery.

I NTRODUCTION • How Did Bronchoscopic I ntubation Develop?

Transmission of a visual image through a flexible fiberoptic bundle was first reported by Hopkins and Kapany in 1 9541 and the first recorded endoscopic tracheal intubation was reported by Murphy in 1 967. 2 In that case report, the trachea of a patient with Still's disease was successfully intubated through the nose using a flexible choledochoscope. 2 1he flexible fiberop­ tic bronchoscope was introduced into clinical practice in 1 964, and although it was not developed for the purpose of airway management, its value as a device to facilitate endotracheal intubation was soon appreciated. 3 ,4 A series of 1 00 tracheal intubations using the flexible bronchoscope was reported in 1 972, with a success rate of 96%.5 However, utilization of flexi­ ble fiberoptic technology for endotracheal intubation remained limited among health care providers throughout the 1 970s and 1 980s.6 Seventy-five percent of those who completed question­ naires at a series of fiberoptic bronchoscope workshops between 1 984 and 1 989 had either no or minimal experience with the technique.6 Following the publication of the ASA Guidelines on Difficult Airway Management in 1 993/ the use of flexible bronchoscopic intubation (FBI) among anesthesia practitioners greatly increased8 and the technique has come to play a pivotal role in the management of the difficult airway.9-1 1 Although i t has been advocated as the technique o f choice in the management of the difficult intubation, 1 2-15 this view is not universally shared and a reluctance to perform awake bronchoscopic intubation continues to occur. 16•17 In 20 1 1 , the 4th National Audit Project of the Royal College of Anesthetists and the Difficult Airway Society (DAS) 10 reported a failure to consider or employ awake bronchoscopic intubation as a first choice in difficult airway management when it was clinically indicated and that harm occurred as a result. However, sur­ veys from the United States, France, and Denmark published between 1 998 and 2003 confirm the widespread use of flexible

F l exi b l e B ro n c h osco p i c I ntu bation

bronchoscopes particularly for management of the anticipated difficult airway. 18-22 A Canadian survey published in 2005 (2066 surveys sent, 47% response rate) revealed that 9 1 . 5 % o f practicing anesthesiologists performed awake bronchoscopic intubation and 89.3% felt comfortable with the technique; 83.6% had performed asleep FBI and 82.7% were comfortable with the technique. 2 3 Anesthesiologists from teaching institu­ tions and younger practitioners had more experience with FBI and were more comfortable with it. Wong et al. 24 repeated this survey with modifications in 20 1 3 (2532 surveys sent, 39o/o response rate) . Ninety-eight percent of respondents had per­ formed awake FBI and 93o/o were comfortable with the tech­ nique. Ninety-one percent had performed asleep FBI and 88% were comfortable with the technique. When presented with an unanticipated difficult intubation with failed direct laryngos­ copy, 4 1 o/o chose FBI as the first choice alternative, whereas 90% chose a video-laryngoscope. 24 In a review of general anes­ thetics administered at a Canadian tertiary care center between 2002 and 20 1 3, 1 46,252 patients underwent endotracheal intubation and of these intubations, 1 5 54 ( 1 .06%) were per­ formed awake. A flexible bronchoscope was used in 99.2% of these awake intubations. The incidence of awake intubation did not change significantly over the period of the study. 2 5 An American study reported a decreasing use of bronchoscopic intubation over 12 years ending in February 20 1 3 . But, it is not clear if bronchoscopic intubation under general anesthesia (GA) was included?6 • When I s Bronchoscopic I nt u bation

I n d icated ?

The primary indication for awake bronchoscopic intubation is in the elective (or at least nonemergency) management of the anticipated difficult airway. The difficult airway can be defined as one in which an experienced practitioner anticipates or encounters difficulty with any or all bag-mask-ventilation, direct or indirect (e.g. , video) laryngoscopy and tracheal intu­ bation, EGO use, or surgical airway. 27 If difficult intubation after induction of GA is predicted with the practitioner's cho­ sen device(s) and ventilation by face-mask or EGO is also predicted to be difficult, awake intubation should be strongly considered. 2 8 Contextual issues such as a predicted short safe apnea time, aspiration risk, and lack of skilled help may also favor an awake technique. 2 8 Although awake intubation can be performed using other devices or combination of devices, awake intubation of the elective surgical patient will most often be performed using a flexible bronchoscope. 2 8 FBI continues to be the accepted standard in elective airway management of the awake spontaneously breathing patient with an anticipated difficult airway, 1 1 and maintains a wide margin of safety. 29-31 NAP4 suggested that there is a need to decrease the thresh­ old for considering awake bronchoscopic intubation as a first choice in difficult airway management. 10 FBI can also be used in the unanticipated difficult airway as an alternative technique when intubation by a primary tech­ nique has failed but ventilation by face-mask or EGO is suc­ cessful (can't intubate, but can oxygenate) . 27'32 ·33 The flexible bronchoscope may also be the preferred device for intubation

after induction of GA by practitioners who are expert in its use.33 However, NAP4 reported that bronchoscopic intuba­ tion under GA was technically more difficult than in an awake cooperative patient due to loss of muscle tone leading to upper airway obstruction. 10 Bronchoscopic intubation was attempted in seven patients reported to the audit after induction of GA either as the primary technique or after failed direct laryngos­ copy. The asleep bronchoscopic intubation failed in all seven patients and all seven required an emergency surgical airway. 10 In general, if airway compromise or respiratory distress exists, awake intubation maintains a wide margin of safety. 2 9 However, in this circumstance, the urgency with which airway control must be achieved and the extent of the airway compromise may limit the choice of technique, and bronchoscopic intuba­ tion may not be feasible or appropriate. In addition, incom­ plete local anesthesia of the upper airway makes bronchoscopic intubation more difficult, as does the presence of blood and secretions in the airway. Complete airway obstruction has been reported following the topical application of local anesthesia to the airway and suctioning in preparation for awake intubation in a stridorous patient with recurrent neck carcinoma and radi­ ation therapy.34 Complete airway obstruction after application of topical local anesthesia to the upper airway was also reported by Shaw et aJ.35 in a patient with a compromised airway sec­ ondary to goiter. Liistro et al.36 demonstrated a transitory but profound obstruction at the level of the glottis or supraglottis during forced inspiratory and expiratory vital capacity maneu­ vers that was produced in normal subjects with local anesthe­ sia of the upper airway. Beydon et al.37 and Kuna et al.38 also found a decrease in upper airway caliber following local anes­ thesia of the airway in normal subjects. Patients with severe airway obstruction due to edema or tumor must be approached with extreme caution if completion airway obstruction is to be avoided4 (see Chapter 3) and due consideration must be given to awake tracheostomy in this setting. 2 8 In the presence of potential cervical spine instability, no intubation technique has been shown to be clearly supe­ rior. 1 1 · 2 9·30·39-43 However, movement of the cervical spine must be minimized during intubation if neurologic injury is to be avoided. FBI can be a valuable alternative in this setting and has been extensively utilized. 1 1.4°.44 Complete airway obstruc­ tion has however been reported during attempted awake bron­ choscopic intubation in this patient population.44.45 In the presence of airway trauma, FBI can permit precise eval­ uation of the injury, facilitate placement of an endotracheal tube (ETT) beyond the level of the injury, 11 and has been said to be the method of choice for airway management in this setting. 1 1.46 Radiation treatment for head and neck cancers can cause edema and fibrosis which can limit mouth opening and neck mobility and distort the submandibular space making direct laryngoscopy difficult or impossible. 1 1.47 Neck radiation is also a predictor of difficult video-laryngoscopy, bag-mask-ventilation, EGO use, and cricothyrotoml8.48; and it is the most signifi­ cant clinical predictor of impossible mask ventilation.49 In the patient who has had neck radiation, awake bronchoscopic intu­ bation can be an invaluable option. Ludwig's angina is a rapidly progressive cellulitis of the floor of the mouth usually caused by odontogenic infection.50.5 1

1 73

1 74

Ai rway Tec h n i q ues

Spread of the infection into the submandibular space pro­ duces edema and swelling which cause superior and posterior displacement of the tongue. 5° Infection in the submandibular space can extend into the lateral and retropharyngeal spaces and thus encircle the airway.50·5 2 Pus accumulation can occur.50 The swelling can involve the larynx and the infection can reach the mediastinum.50 Neck movement can be restricted. 50 Trismus can be severe and may not improve with neuromuscu­ lar blockade. 53 Although less advanced deep neck infection can be managed by antibiotics alone, true Ludwig's angina typically requires definitive airway control and surgical drainage. 54 Face­ mask-ventilation, EGO use, direct and video-laryngoscopy, and surgical airway can all be difficult.5354 Awake tracheotomy under local anesthesia has been considered the gold standard airway management in this setting, however awake FBI has also been used with a high success rate55 and can be a feasible alternative. 5 2 FBI can also be used as an alternative to direct laryngoscopy in any patient for whom intubation is indicated, and in particu­ lar when a high risk of dental injury exists.4

F I G U R E 1 0- 1 . The a d u lt fl ex i b l e bron c hoscope. An Olym p u s BF-XT1 60 i s s h own here w i t h a n i n sertio n cord d i a meter o f 6.3 m m a n d a length o f 60 e m .

• When Is FBI Best Avoided?

Contraindications to FBI must be considered relative and weighed against the risks associated with alternative airway management techniques. 29 Some measure of patient coop­ eration is required for awake FBI, and the total absence of cooperation may preclude this technique, as can bleeding in the airway and massive tissue disruption.4• 29·1 1 • 2 8 Fixed laryn­ geal obstruction with stridor at rest implies a reduction in the caliber of the airway to 4.0 mm or less in diameter.56 FBI is unlikely to be successful in this setting and at best will produce a higher grade of obstruction when the scope is passed through the involved area. In this setting, a surgical airway (e.g. , awake tracheotomy) performed under local anesthesia is a better alter­ native.57 FBI is contraindicated when immediate airway control is necessary and the time required to complete the procedure is not available. 8 Patient refusal in the adult population without psychiatric disease is exceedingly rare if an appropriate explanation of the procedure has been provided.

EQU I PM E NT • How Do Flexible Bronchoscopes Work? What

Is the Best I n strument for FBI?

The standard "adult" flexible bronchoscope remains unsur­ passed as an instrument with which to perform bronchoscopic intubation in the vast majority of circumstances in the adult population. These bronchoscopes have a sufficient length (about 60 em) to accommodate an ETT ensleeved proximally while leaving an adequate distal segment for maneuverability. Shorter flexible fiberscopes tend to make FBI more difficult. A bronchoscope with an outside diameter of 5 . 9 and 6.0 mm will readily accommodate a 7-mm internal diameter (ID) ETT and has adequate stiffness to function well as a stylet over which to advance the ETT (see Figure 10-1) . 29·58 Bronchoscopes with

F I G U R E 1 0-2. T h e "ped iatric" fl exi b l e bronchoscope. An Olym p u s LF2 i s s h own h e re w i t h a n i n sertion cord d i a m ete r o f 4 m m a n d a length of 60 e m . N ote the i n c reased fl exi b i l ity of the t h i n n e r i n sertio n cord.

thinner insertion cords tend to be more flexible and form a floppy stylet that is easily buckled away from the glottis as the ensleeved ETT is advanced into the airway (see Figure 1 0-2) . 30 The flexible bronchoscope consists of a proximal handle and a distal insertion cord or shaft. An umbilical or universal cord is attached to the side of the handle and connects the bron­ choscope to an external light source (see Figure 1 0-3) . Modern flexible bronchoscopes include fiberoptic bronchoscopes, video bronchoscopes, and hybrid designs. Flexible bronchoscopes are also available with a battery-operated light source, which greatly improves portability. The handle of the bronchoscope is fitted with a lever which controls flexion of the tip of the scope (the bending section) 14•59 in a single plane; the movement of the tip being produced by two wires which connect the control lever to the tip of the scope (see Figure 1 0-3) . 14 The handle also contains the proximal port of the working channel which

F l exi b l e B ro n c h osco p i c I ntu bation

Ai r/water nozzle Objective lens

Focusing ring

F I G U R E 1 0-3. Feat u res of the fl ex i b l e bro n c h oscope: it consists of a proxi m a l h a n d l e a n d a d i sta l i n sertion cord o r shaft. An u m b i l ic a l or u n ivers a l cord i s attached t o the s i d e o f the h a n d l e a n d con­ nects the b ro n c h oscope to an exte r n a l l i g ht s o u rce. The h a n d l e a l s o conta i n s t h e proxi m a l port o f the worki ng c h a n nel, a s uction port, and the fl exio n l eve r.

video processor electronically

�

Light g u ide bundle ( i l l u m i nation fi beroptics)

60 seconds and more than one required attempt to achieve intubation. Their analysis considered difficulties encountered with either blade though their prior study identi­ fied that they were nonequivalent. 158 As mentioned previously, difficulties were encountered more commonly in patients in the supine sniffing position, with limited mouth opening, present­ ing for cardiac or otolaryngologic surgery or those intubated by attending anesthesiologists. The laryngeal view also tended to

be worse in patients in whom difficulties were encountered. It is interesting but not surprising that the sniffing position made intubation more difficult; this is likely a consequence of the dif­ ficulties placing an acutely angled-laryngoscope into the mouth without its handle abutting on the patient's chest. Furthermore, experience as a laryngoscopist does not necessarily confer exper­ tise as a video-laryngoscopists, however it also possible that the more challenging patients were intubated by attending anesthe­ siologists rather than trainees or other practitioners. • McGrath Video-La ryngoscope

The McGrath VL Series5" (MGL5) was developed by indus­ trial designer, Matt McGrath, and is manufactured by Aircraft Medical in Edinburg Scotland, now a division of Medtronic (Dublin) . Introduced in Europe in January 2006, the MGL is compact and lightweight. It is ergonomically designed and powered by a single 1 . 5 V AA NiMH or lithium battery housed in its handle. It consists of an adjustable stainless steel "CameraStick'M" that can be advanced or retracted to three different lengths. The handle is a comfortable, medical grade hard rubber. A 1 .7-inch (diagonal, 3 . 3 X 2.25 em) LCD screen (320 X 280 pixels) is mounted atop the handle and can be tilted and swiveled for an optimal viewing angle (Figure 1 1 -20) . The power button is located o n the top o f the handle. The CameraStick contains rwo high-intensity LEOs and a CMOS video camera. A single-use, low-profile, polycarbonate blade cover with a maximal height of 1 3 mm covers the CameraS tick and has been treated to reduce condensation on the blade. An ETT should be prepared with a stylet and used in a manner similar to that of the GlideScope and C-MAC 0-blade, both described above. The blade is introduced into the mouth in the midline until the tip passes beyond the base of the tongue. An ETT is introduced into the mouth under direct vision, close to the laryngoscope blade. Keeping the ETT close to the tongue and laryngoscope blade, the tip is introduced into the glottis and the stylet is partially or fully withdrawn. The McGrath Series5 has now been superseded by the McGrath MAC Enhanced Direct Laryngoscope (Figure l l-2 1 ) . Like other Macintosh-style VL devices, the McGrath MAC EDL claims to offer the advantages of direct and indirect view­ ing. Compared with its predecessor, the camera stick is in a fixed position, with a 2 . 5 -inch display having a portrait orien­ tation and swiveling in a single plane. It is powered by a pro­ prietary 250-minute lithium ion battery. The time remaining on the battery is displayed numerically on the screen. It has low-profile ( 1 1 .9 mm) , single-use polycarbonate blade covers that are available in sizes 2, 3, and 4 in the Macintosh con­ figuration. An acutely angled X3 blade should prove useful in settings where the laryngeal view is more difficult. Portability and relatively inexpensive capital and disposable costs make this device easy to justify for routine use. It lacks recording capabil­ ity and is susceptible to some degree of fogging. H ow Is t h e McGrath MAC Used?

There are very few English language publications concern­ ing the McGrath MAC involving human subjects. Most of these are single-case reports. The McGrath MAC has been

21 5

216

Ai rway Tec h n i q ues

F I G U R E 1 1 -2 1 . McG rath MAC E n h a nced Di rect La ryngoscope (McGrath MAC E D L) . The ca mera stick i s i n a fixed position and vari­ o u s s i n g l e-use blades (Maci ntosh 2, 3 , 4 a s wel l a s a s ize 3 X-b l a d e) provi d i n g a non-l i n e of s i g h t view for d iffi c u l t a i rways. (Used with perm ission fro m Medtro n ic, B o u l d e r, Col o rado)

had similar airway characteristics, however the investigators observed lower Intubation Difficulty Scores162 and utilized the least effort when indirect viewing was used. Interestingly, although the laryngeal view was best with indirect viewing and the IDS was lower in the indirect group, all three groups were easily intubated. Indeed, not 1 of the 1 5 8 patients presented even moderate difficulty with direct or indirect viewing. They also observed poorer performance using the McGrath MAC as a direct device compared with indirect viewing or a conven­ tional Macintosh DL. 163

COM P LICATIONS OF VL F I G U R E 1 1 -20. The McGrath Series 5 video-la ryngosco pe. I t i s enti re l y self-co nta i ned w i t h a n adju sta b l e "ca m e ra stick" a n d s i n g le­ use p l a stic a n g u l ated b l a d e cove rs. (U sed with perm ission fro m Medtro n ic, B o u l d e r, Colora d o)

used successfully after a failed attempt with a Pentax AWS in a patient with a halo vest, 159 in a child with Treacher Collins Syndrome in whom a CL 4 view by Macintosh-DL was con­ verted to a C-L 1 , 160 and better laryngeal views requiring fewer intubation attempts using a double-lumen tube. 161 In a study of 1 5 8 patients, Wallace and coworkers compared Macintosh-DL with McGrath direct and indirect views. The three groups

Perforation of the right anterior tonsillar pillar (or palatopha­ ryngeal fold) has been described with the GVL. 1 26•127 1his com­ plication is not a consequence of the stylet or introducer, but results from the laryngoscopist blindly introducing the ETT into the oropharynx while observing the monitor. This compli­ cation is not limited to the GVL and has occurred with other indirect techniques since the camera is located toward the distal end of the laryngoscope blade. Thus the monitor is blind to the ETT advancement between the lips and the camera. Aziz observed complications in 2 1 of 2,004 GVL uses, 1 3 of which were minor including lip and gum lacerations. This is prob­ ably comparable to that observed with DL though this study

R i g i d F i b e ro ptic a n d Video-Laryngoscopes

was not designed to enable such a conclusion. Perforation of the tonsillar pillar occurred in one patient. 20 Such perforation has generally been managed conservatively, with vigilance to ensure the absence of a delayed infection. When comparing the C-MAC to DL in patients with features suggesting a dif­ ficult airway, there was no difference in the complication rate between the devices. 157 It is the opinion of the current authors that a reduction in the incidence of blind, esophageal, and mul­ tiple attempts at intubation is a greater benefit than the risk of airway trauma, especially if the laryngoscopist directly observes ETT insertion into the mouth until it passes the camera.

S U M MARY Video-laryngoscopes enjoy growing acceptance in the anes­ thesiology communiry164 and are advocated by some as a new standard of care for facilitating tracheal intubation. 151·165•166 Our poor ability to reliably predict patients in whom a line-of­ sight technique will fail to reveal the larynx means that many will undergo multiple attempts with increasing force and may ultimately be intubated blindly or unsuccessfully. Even when features suggest that DL will not be difficult, it proves to be otherwise at least 6o/o to l Oo/o of the time.5•9•162 Multiple and blind attempts are associated with an increased risk of compli­ cations, particularly in critically ill patients. 167 VL provides a more predictable laryngeal view, even in less experienced hands but does not always ensure that intubation can be accom­ plished despite a good laryngeal view. Increased success comes with a better understanding that the skills required for DL and VL are related but different. Proficiency is best acquired and maintained by practicing with these devices when they are not thought to be necessary and incorporating selected devices into routine practice. This does not compromise patient safety; if the less familiar device fails, the laryngoscopist can revert to the more familiar. This strategy will better equip the laryngosco­ pist with the j udgement required to identifY situations that are within or beyond his/her skill level. It is unlikely that a single device or even a class of devices will emerge as a solution to every airway challenge. Thus, it is important to retain a range of skills that include ventilation using a face-mask or extraglottic device, direct and indirect laryngoscopy, flexible bronchoscopic intubation and if all these fail, the ability to quickly perform an emergency surgical airway.

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Ai rway Tec h n i q ues 3 1 . Levitan RM . Design rationale and intended use of a short optical stylet for routine fiberoptic augmentation of emergency laryngoscopy. Am J Emerg Med. 2006;24:490-495. 32. Kitamura T, Yamada Y, Du HL, Hanaoka K. Efficiency of a new fiberoptic stylet scope in tracheal intubation. Anesthesiology. 1 999;9 1 : 1 628-1 632. 33. Halligan M, Charters P. A clinical evaluation of the Bonfils intubation fibrescope. Anaesthesia. 2003 ; 5 8 : I 087 -I 09 1 . 34. Bein B , Worthmann F, Scholz J , et al. A comparison o f the intubating laryngeal mask airway and the Bonfils intubation fibrescope in patients with predicted difficult airways. Anaesthesia. 2004; 59:668-674. 3 5 . Takenaka !, Aoyama K, Kadoya T, Sara T, Shigematsu A. Fibreoptic assessment of laryngeal aperture in patients with difficult laryngoscopy. Can } Anaesth. 1 999;46:226-23 1 . 36. Rudolph C , Schlender M . Clinical experiences with fiber optic intu­ bation with the Bonfils intubation fiberscope. 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A comparison of Bonfils intubation fibers­ copy and fiberoptic bronchoscopy in difficult airways assisted with direct laryngoscopy. Korean ] Anesthesia!. 20 1 0; 5 8 :249-2 5 5 . 48. Shollik NA, Ibrahim S M , lsmael A , Agnoletti V, Piraccini E, Corso RM . Use of the bonfils intubation fiberscope in patients with limited mouth opening. Case Rep Anesthesia!. 20 1 2;20 1 2:297306. 49. Liew G, Leong XF, Wong T. Awake tracheal intubation in a patient with a supraglottic mass with the Bonfils fibrescope after failed attempts with a flexible fibrescope. Singapore Medj. 20 1 5 ; 5 6 : e l 39-e 1 4 1 . 5 0 . Mazeres JE, Lefranc A , Cropet C , e t al. Evaluation o f the Bon fils intubat­ ing fibrescope for predicted difficult intubation in awake patients with ear, nose and throat cancer. Eur} Anaesthesia!. 20 I I ;28:646-650. 5 1 . Corbanese U, Possamai C. Awake intubation with the Bonfils fibrescope in patients with difficult airway. Eur j Anaesthesia!. 2009;26: 837-84 1 . 52. 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58. Rudolph C, Schneider JP, Wallen born J, Schaffranietz L. Movement of the upper cervical spine during laryngoscopy: a comparison of the Bonfils intubation fibrescope and the Macintosh laryngoscope. Anaesthesia. 2005;60: 668-672. 59. Wahlen BM, Gercek E. Three-dimensional cervical spine movement during intubation using the Macintosh and Bullard laryngoscopes, the bonfils fibrescope and the intubating laryngeal mask airway. Eur } Anaesthesia!. 2004;2 1 : 907-9 1 3 . 6 0 . Turkstta T P, Pelz O M , Shaikh AA, Craen RA . Cervical spine motion: a fluoroscopic comparison of Shikani Optical Stylet' vs Macintosh laryn­ goscope. Can }Anesth. 2007; 54:44 1 -447. 6 1 . Subramani S, Poopalalingam R. Bonfils assisted double lumen endobron­ chial tube placement in an anticipated difficult airway. } Anaesthesia! Clin Pharmacal. 20 1 4;30:568-570. 62. Yang M, Kim J, Ahn H, Choi J, Kim D, Cho E. Double-lumen tube tracheal intubation using a rigid video-stylet: a randomized controlled comparison with the Macintosh laryngoscope. Br J Anaesth. 20 1 3; 1 1 1 : 990-995. 63. Hsu HT, Chou SH, Chen CL, et al. Left endobronchial intubation with a double-lumen tube using direct laryngoscopy or the Trachwal video stylet. Anaesthesia. 20 1 3;68:85 1 - 8 5 5 . 6 4 . H s u H-T, Lin C-H, Tseng K-Y, e t al. Trachway in assistance of nasotra­ cheal intubation with a preformed nasotracheal tube in patients undergo­ ing oral maxillofacial surgery. Br} Anaesth. 2 0 1 4; 1 1 3 :720-72 1 . 6 5 . Lee MC, Tseng KY, Shen YC, e t al. Nasotracheal intubation i n patients with limited mouth opening: a comparison between fibreoptic intubation and Trachway. Anaesthesia. 20 1 6;7 1 :3 1 -38. 66. Shukry M, Hanson RD, Koveleskie JR, Ramadhyani U. Management of the difficult pediatric airway with Shikani Optical Stylet'M. Pediatr Anesth. 2005 ; 1 5 :342-345 . 6 7 . Stricker P, Fiadjoe J, McGinnis S . Intubation of a n infant with Pierre Robin sequence under dexmedetomidine sedation using the Shikani Optical Stylet'M. Acta Anaesthesia! Scand. 2008;52: 866-867. 68. Aucoin S, Vlatten A, Hackmann T. Difficult airway management with the Bonfils fiberscope in a child with Hurler syndrome. Pediatr Anesth. 2009; 1 9:42 1 -422. 69. Jansen AH, Johnston G. The Shikani Optical Stylet: a useful adjunct to airway management in a neonate with popliteal pterygium syndrome. Pediatr Anesth. 2008; 1 8 : 1 88 - 1 90. 70. Camselli M, Zannini R, Giretti R, et al. Difficult intubation in a small for gestational age newborn by bonfils fiberscope. Pediatr Anesth. 2008; 1 8 : 990-99 1 . 7 1 . Bein B, Wortmann F, Meybohm P, Steinfath M, Scholz J, Doerges V. Evaluation of the pediatric Bonfils fiberscope for elective endotracheal intubation. Pediatr Anesth. 2008; 1 8 : I 040- 1 044. 72. Houston G, Bourke P, Wilson G, Engelhardt T. Bonfils intubating fibre­ scope in normal paediatric airways. Br J Anaesth. 20 1 0 ; 1 05 : 546-547. 73. Kaufmann J, Laschat M, Hellmich M, Wappler F. A randomized con­ trolled comparison of the Bonfils fiberscope and the GlideScope Cobalt AVL video laryngoscope for visualization of the larynx and intubation of the trachea in infants and small children with normal airways. Pediatr Anesth. 20 1 3;23:9 1 3-9 1 9 . 74. Kaufmann J, Laschat M, Engelhardt T, Hellmich M, Wappler F. Tracheal intubation with the Bonfils fiberscope in the difficult pediatric airway: a comparison with fiberoptic intubation. Pediatr Anesth. 20 1 5 ;25: 372-378. 75. Jagannathan N, Kho MF, Kozlowski RJ, Sohn LE, Siddiqui A, Wong DT. Retrospective audit of the air-Q intubating laryngeal airway as a conduit for tracheal intubation in pediatric patients with a difficult airway. Pediatr Anesth. 20 1 1 ;2 1 :422-427. 76. Drolet S, Michaud S . Bonfils intubation in parallel with a supraglottic air-Q• intubating laryngeal airway. Can } Anesth. 20 1 6;63 : 5 0 1 -502. 77. Hemmerling TM, Bracco D. Subcutaneous cervical and facial emphy­ sema with the use of the Bon fils fiberscope and high-flow oxygen insuf­ flation. Anesth Ana/g. 2008 ; 1 06:260-262. 78. Najafi A, Rahimi E, Moharari RS, Khan ZH. Bonfils fiberscope: intubat­ ing conditions and hemodynamic changes without neuromuscular block­ ade. Acta Med iran. 20 1 1 ;49:20 1 -207. 79. Boker A, Almarakbi WA, Arab AA, Almazrooa A. Reduced hemo­ dynamic responses to tracheal intubation by the Bonfils retromolar fiberscope: a randomized controlled study. Middle East J Anaesthesia!. 20 1 1 ;2 1 :38 5-390. 80. Kitamura T, Yamada Y, Chinzei M, Du HL, Hanaoka K. Attenuation of haemodynamic responses to tracheal intubation by the styletscope. Br } Anaesth. 200 1 ;86:275-277. 8 1 . Kimura A, Yamakage M, Chen X, Kamada Y, Namiki A. Use of the fibreoptic stylet scope (Styletscope) reduces the hemodynamic response

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101.

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105.

1 06.

to intubation in normotensive and hypertensive patients. Can j Anaesth. 200 1 ;48: 9 1 9-923. Gupta K, Girdhar KK, Anand R, Majgi SM, Gupta SP, Gupta PB. Comparison of haemodynamic responses to intubation: flexible fibre­ optic bronchoscope versus bon fils rigid intubation endoscope. Indian } Anaesth. 201 2;56:353. Cooper RM , Law JA. Rigid fiberoptic and video laryngoscopes. In: Hung 0, Murphy MF, eds. Management ofthe Difficult and Failed Airway. 2nd ed. New York, NY: McGraw Hill; 20 1 1 : 1 5 9- 1 85 . Cooper RM . The role of rigid fiberoptic laryngoscopes. I n : Glick DB, Cooper RM , Ovassapian A, eds. The Difficult Airway: An Atlas of Tools and Techniques for Clinical Management. New York, NY, Springer; 20 1 3 :65-76. Abrams KJ, Desai N, Katsnelson T. Bullard laryngoscopy for trauma airway management in suspected cervical spine injuries. Anesth Analg. 1 992;74:623. Cohn AI, Hart RT, McGraw SR, Blass NH. The Bullard laryngoscope for emergency airway management in a morbidly obese parturient. Anesth Ana/g. 1 995;8 1 :872-873. Cohn AI, Zornow MH. Awake endotracheal intubation in patients with cervical spine disease: a comparison of the Bullard laryngoscope and the fiberoptic bronchoscope. Anesth Analg. 1 995;8 1 : 1 283-1 286. Dullenkopf A, Lamesic G, Gerber A, Weiss M. Video-enhanced visualiza­ tion of the larynx and intubation with the Bullard laryngoscope-equip­ ment report. Can JAnesth. 2003;50: 507-5 1 0. Gorback MS. Management of the challenging airway with the Bullard laryngoscope. J Clin Anesth. 1 99 1 ;3 :473-477. Hastings RH, Vigil AC, Hanna R, Yang BY, Sartoris OJ. Cervical spine movement during laryngoscopy with the Bullard, Macintosh, and Miller laryngoscopes. Anesthesiology. 1 995;82:859-869. MacQuarrie K, Hung OR, Law JA. Tracheal intubation using Bullard laryngoscope for patients with a simulated difficult airway. Can} Anaesth. 1 999;46:760-765. Crosby E, Skene D. More on lingual tonsillar hypertrophy. Can j Anesth. 2002;49:758. Andrews SR, Mabey MF. Tubular fiberoptic laryngoscope (WuScope) and lingual tonsil airway obstruction. Anesthesiology. 2000;93:904-905. Sprung J, Weingarten T, Dilger J. The use ofWuScope fiberoptic laryngos­ copy for tracheal intubation in complex clinical situations. Anesthesiology. 2003;98 :263-265. Sprung ] , Wright LC, Dilger ]. Use of WuScope for exchange of endotracheal tube in a patient with difficult airway. Laryngoscope. 2003; 1 1 3 : 1 082- 1 084. Wu TL, Chou HC. WuScope versus conventional laryngoscope in cervi­ cal spine immobilization. Anesthesiology. 2000;93:588-589. Li JB, Xiong YC, Wang XL, et al. An evaluation of the TruView EV02 laryngoscope. Anaesthesia. 2007;62: 940-943. Saxena A, Madan M, Shrivastava U, et al. Role of the Truview EV02 laryngoscope in the airway management of elective surgical patients: a comparison with the Macintosh laryngoscope. Indian } Anaesth. 20 1 3;57:276-28 1 . Weiss M , Hartmann K, Fischer JE, Gerber AC. Use o f angulated video­ intubation laryngoscope in children undergoing manual in-line neck sta­ bilization. Br } Anaesth. 200 1 ; 87:453-45 8 . Cierniak M, Timler D, Wieczorek A , Sekalski P, Borkowska N, Gaszynski T. The comparison of the technical parameters in endotracheal intubation devices: the CMAC, the VividTrac, the McGrath MAC and the King Vision. } Clin Manit Comput. 20 1 5;30: 1 -9. Suzuki A, Katsumi N, Honda T, et al. Displacement of the epiglot­ tis during intubation with the Pentax-AWS Airway Scope. } Anesth. 20 1 0;24: 1 24- 1 27. Suzuki A, Abe N, Sasakawa T, Kunisawa T, Takahata 0, Iwasaki H . Pentax-AWS (Airway Scope) and Airtraq: b i g difference between rwo similar devices. } Anesth. 2008;22: 1 9 1 - 1 92. Suzuki A, Ohmura T, Tampo A, et al. Parker Flex-Tip Tube" provides higher intubation success with the Pentax-AWS Airwayscope' despite the AWS tip being inserted into the vallecula. } Anesth. 20 1 2;26:6 1 4-6 1 6. Adnet F, Barron SW, Racine SX, et al. The intubation difficulty scale (IDS) : proposal and evaluation of a new score characterizing the complexity of endotracheal intubation. Anesthesiology. 1 997;87: 1 290- 1 297. Levitan RM , Ochroch EA, Kush S, Shafer FS, Hollander JE. Assessment of airway visualization: validation of the percentage of glottic opening (POGO) scale. Acad Emerg Med. 1 998; 5 : 9 1 9-923. Lu Y, Jiang H, Zhu YS . Airtraq laryngoscope versus conventional Macintosh laryngoscope: a systematic review and meta-analysis. Anaesthesia. 20 1 1 ;66: 1 1 60- 1 1 67.

1 07. Suppan L, Tramer MR, Niquille M, Grosgurin 0, Marti C. Alternative intubation techniques vs Macintosh laryngoscopy in patients with cervi­ cal spine immobilization: systematic review and meta-analysis of random­ ized controlled trials. Br J Anaesth. 20 1 6; 1 1 6:27-36. 1 08 . Hirabayashi Y, Sea N. Airway Scope: early clinical experience in 405 patients. } Anesth. 2008;22: 8 1 -8 5 . 1 09. Suzuki A , Toyama Y, Katsumi N, e t al. The Pentax-Aws• rigid indirect video laryngoscope: clinical assessment of performance in 320 cases. Anaesthesia. 2008;63 : 64 1 -647. 1 1 0. Asai T, Liu EH, Matsumoto S, et al. Use of the Pentax-Aws· in 293 patients with difficult airways. Anesthesiology. 2009; 1 1 0: 898-904. 1 1 1 . Hoshijima H, Kuratani N, Hirabayashi Y, Takeuchi R, Shiga T, Masaki E. Pentax Airway Scope• vs Macintosh laryngoscope for tracheal intuba­ tion in adult patients: a systematic review and meta-analysis. Anaesthesia. 20 14;69:9 1 1 -9 1 8 . 1 1 2. Kleine-Brueggeney M, Greif R, Schoettker P, Savoldelli GL, Nabecker S , Theiler LG . Evaluation o f six videolaryngoscopes i n 720 patients with a simulated difficult airway: a multicentre randomized controlled trial. Br } Anaesth. 20 1 6; 1 1 6:670-679. 1 1 3 . Murphy LD, Kovacs GJ, Reardon PM, Law JA. Comparison of the King Vision video laryngoscope with the Macintosh laryngoscope. J Emerg Med. 2 0 1 4;47:239-246. 1 1 4. Sowers N, Kovacs G. Use of a flexible intubating scope in combination with a channeled video laryngoscope for managing a difficult airway in the emergency department. J Emerg Med. 20 1 6;50:3 1 5-3 1 9 . 1 1 5 . El-Tahan MR, Doyle OJ, Khidr AM, Abdulshafi M, Regal MA, Othman MS. Use of the King Vision video laryngoscope to facilitate fibreoptic intubation in critical tracheal stenosis proves superior to the GlideScope•. Can }Anaesth. 2 0 1 4;6 1 : 2 1 3-2 1 4 . 1 1 6. El-Tahan MR, Doyle OJ, Khidr AM, Regal MA, E l Morsy A B , E l Mahdy M. Awake tracheal intubation with combined use of King Vision vide­ o laryngoscope and a fiberoptic bronchoscope in a patient with giant lym­ phocele. Middle East J Anaesthesia!. 20 1 4;22:609-6 1 2 . 1 1 7. Gaszynski T. A combination of KingVision video-laryngoscope and flexi­ ble fibro scope for awake intubation in patient with laryngeal tumor-case report and literature review. Anaesthesia! Intensive Ther. 20 1 5 ;47:433-43 5 . 1 1 8 . Butchart A , Young P. Correspondence: use of a Venner A . P. Advance videolaryngoscope in a patient with potential cervical spine inj ury. Anaesthesia. 20 1 0;65:953-954. 1 1 9. Butchart AG, Tjen C, Garg A, Young P. Paramedic laryngoscopy in the simulated difficult airway: comparison of the Venner A.P. Advance and GlideScope ranger video laryngoscopes. Acad Emerg Med. 20 1 1 ; 1 8 :692-698. 1 20. Hughes J, Paul R, O'Flynn P. Use of the Venner A.P. Advance video laryngoscope for biopsy examination of the base of the tongue. Br J Oral Maxillofac Surg. 20 1 2 ; 5 1 (2) : e22-23. 1 2 1 . Zampone S, Corso RM , Parrinello L, Gambale G, Sorbello M. The A.P. advance video laryngoscope as a rescue airway device in an unpredicted difficult airway. J Anaesthesia! Clin Pharmacal. 20 1 5;3 1 : 1 34- 1 36. 1 22. Cooper RM . Icteric vocal cords recorded during video laryngoscopy. Anesthesiology. 2 0 1 3 ; 1 1 9 : 1 469. 1 23 . Telgarsky B, Cooper RM , Monteiro E, de AJR. Epiglottic melanosis. Can J Anesth. 20 1 5;62: 1 22 1 . 1 24. Rothfield KP. GlideScope improves EMS field intubation success after simulator training only. ASA Annual Meeting 20 1 1 , St. Agnes Hospital, Baltimore, MD. 20 1 1 . 1 2 5 . Ayoub CM, Kanazi GE, Al Alami A, Rameh C, El-Khatib MF. Tracheal intubation following training with the GlideScope compared to direct laryngoscopy. Anaesthesia. 20 1 0;65:674-678. 1 26. Cooper RM . Complications associated with the use of the GlideScope videolaryngoscope. Can J Anesth. 2007; 54: 54-57. 1 27. Chao MKF, Yeo VST, See JJ. Another complication associated with vide­ olaryngoscopy. Can J Anesth. 2007;54:322-324. 128. Cooper RM , Pacey JA, Bishop MJ, McCluskey SA. Early clinical experience with a newvideolaryngoscope (GlideScope). Can JAnesth. 2005;52: 1 9 1 - 1 98. 1 29. Mihai R, Blair E, Kay H, Cook TM. A quantitative review and meta­ analysis of performance of non-standard laryngoscopes and rigid fibreop­ tic intubation aids. Anaesthesia. 2008;63 :745-760. 1 30. Frerk C, Lee G. Laryngoscopy: time to change our view. Anaesthesia. 2009;64:3 5 1 -354. 1 3 1 . Apfelbaum JL, Hagberg CA, Caplan RA, et al. Practice guidelines for management of the difficult airway: an updated report by the American Sociery of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology. 20 1 3 ; 1 1 8:25 1 -270. 1 32. Cook TM, Woodall N, Frerk C. Fourth National Audit Project of the Royal College of Anaesthetists and Difficult Airway Society. Major com­ plications of airway management in the United Kingdom. Report and

21 9

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Ai rway Tec h n i q ues

1 33 .

1 34.

135. 1 36.

1 37.

1 38 .

1 39.

1 40.

141.

1 42.

1 43 .

1 44.

145.

1 46.

1 47.

1 48 .

1 49.

1 50.

151. 1 52.

1 53 .

1 54. 1 55.

1 56.

findings. Royal College of Anaesthetists London. 201 1 . Available at: http:/ /www. rcoa.ac. uk/ nap4. Law JA, Broemling N, Cooper RM , et al. The difficult airway with recommendations for management-part !-difficult tracheal intuba­ tion encountered in an unconscious/induced patient. Can } Anesth. 20 1 3 ;60: 1 0 8 9- 1 1 1 8 . Law JA, Broemling N, Cooper RM , e t al. Th e difficult airway with rec­ ommendations for management-part 2-the anticipated difficult air­ way. Can }Anesth. 2 0 1 3;60: 1 1 1 9- 1 1 38 . Asai T. Videolaryngoscopes: d o they have role during rapid-sequence induction of anaesthesia? Br} Anaesth. 20 1 6; 1 1 6: 3 1 7-3 1 9 . Andersen L , Rovsing L , Olsen K . GlideScope videolaryngoscope vs. Macintosh direct laryngoscope for intubation of morbidly obese patients: a randomized trial. Acta Anaesthesia! Scand. 20 1 1 ; 5 5 : 1 090- 1 097. Aziz MF, Kim D, Mako J, Hand K, Brambrink AM. A retrospective study of the performance of video laryngoscopy in an obstetric unit. Anesth Ana/g. 20 1 2; 1 1 5 :904-906. Hinkelbein J, Cirillo F, De Robertis E, Spelten 0. Update on video laryn­ goscopy in the emergency environment: the most important publications of the last 12 months. Trends Anaesth Crit Care. 2 0 1 5 ; 5 : 1 88- 1 94. Mosier J, Chiu S, Patanwala AE, Sakles J C. A comparison of the GlideScope video laryngoscope to the C-MAC video laryngoscope for intubation in the emergency department. Ann Emerg Med. 20 1 3; 6 1 (4) :4 1 4-420. Mosier J, Whitmore SP, Bloom JW, et al. Video laryngoscopy improves intubation success and reduces esophageal incubations compared to direct laryngoscopy in the medical intensive care unit. Crit Care. 2 0 1 3 ; 1 7:R237. Sakles JC, Mosier JM, Chiu S, Keim SM. Tracheal intubation in the emer­ gency department: a comparison of GlideScope0 video laryngoscopy to direct laryngoscopy in 822 incubations. J Emerg Med. 20 1 2;42:400-405. Griesdale DE, Liu D, McKinney J, Choi PT. Glidescope0 video­ laryngoscopy versus direct laryngoscopy for endotracheal intubation: a systematic review and meta-analysis. Can } Anesth. 20 1 2;59:4 1 -52. lbinson JW, Ezaru CS, Cormican DS, Mangione MP. GlideScope Use improves intubation success rates: an observational study using propen­ sity score matching. BMC Anesthesia!. 20 14; 1 4: 1 0 1 . Choi HJ, Kim YM, O h YM, Kang HG, Yim HW, Jeong SH. GlideScope video laryngoscopy versus direct laryngoscopy in the emergency depart­ ment: a propensity score-matched analysis. BM} Open. 20 1 5; 5 : e007884. Mosier JM, Stolz U, Chiu S, Sakles JC. Difficult airway management in the emergency department: GlideScope videolaryngoscopy compared to direct laryngoscopy. J Emerg Med. 20 1 2;42:629-634. Griesdale DE, Chau A, !sac G, et al. Video-laryngoscopy versus direct laryngoscopy in critically ill patients: a pilot randomized trial. Can J Anaesth. 2 0 1 2; 5 9 : 1 032- 1 039. Hypes CD, Stolz U, Sakles JC, et al. Video laryngoscopy improves odds of first-attempt success at intubation in the intensive care unit. A propen­ sity-matched analysis. Ann Am 7horac Soc. 20 1 5 ; 1 3 : 3 82-390. Silverberg MJ, Li N, Acquah SO, Kory PD. Comparison of video laryn­ goscopy versus direct laryngoscopy during urgent endotracheal intuba­ tion: a randomized controlled trial. Crit Care Med. 20 1 5 ;43:636-64 1 . D e Jong A, Molinari N , Conseil M , e t al. Video laryngoscopy versus direct laryngoscopy for orotracheal intubation in the intensive care unit: a systematic review and meta-analysis. Intensive Care Med. 20 1 4;40: 629-639. Frerk C, Mitchell VS, McNarry AF, et al. Difficult Airway Society 20 1 5 guidelines for management o f unanticipated difficult intubation in adults. Br J Anaesth. 20 1 5 ; 1 1 5 : 827-848. Kelly FE, Cook TM. Seeing is believing: getting the best out of videolar­ yngoscopy. Br J Anaesth. 20 1 6; 1 1 7 (suppl 1 ) : i9-i 1 3 . Cavus E , Kieckhaefer J, Doerges V, Moeller T, Thee C, Wagner K . The C-MAC videolaryngoscope: first experiences with a new device for vide­ olaryngoscopy-guided intubation. Anesth Analg. 20 1 0; 1 1 0:473-477. Cavus E, Neumann T, Doerges V, et al. First clinical evaluation of the C-MAC D-Biade videolaryngoscope during routine and difficult intuba­ tion. Anesth Ana/g. 2 0 1 1 ; 1 1 2:382-3 8 5 . Kaplan MB, Ward D S , Berci G. A new videolaryngoscope-an aid in intubation and teaching. J Clin Anesth. 2002; 14(8):620-626. Kaplan MB, Hagberg CA, Ward DS, et al. Comparison of direct and video-assisted views of the larynx during routine intubation. J Clin Anesth. 2006; 1 8 :3 57-362. Cavus E, Thee C, Moeller T, Kieckhaefer J, Doerges V, Wagner K. A ran­ domised, controlled crossover comparison of the C-MAC video laryngo­ scope with direct laryngoscopy in 1 5 0 patients during routine induction of anaesthesia. BMC Anesthesia!. 2 0 1 1 ; 1 1 : 6.

1 57. Aziz MF, Dillman D, Fu R, Brambrink AM. Comparative effectiveness of the C-MAC" video laryngoscope versus direct laryngoscopy in the setting of the predicted difficult airway. Anesthesiology. 2 0 1 2; 1 1 6:629-636. 1 5 8 . Aziz MF, Abrons RO, Caetano D, et al. First-attempt intubation suc­ cess of video laryngoscopy in patients with anticipated difficult direct laryngoscopy: a multicenter randomized controlled trial comparing the C-MAC D-Biade versus the GlideScope in a mixed provider and diverse patient population. Anesth Analg. 20 1 6 ; 1 22:740-750. 1 5 9. Hyuga S, Sekiguchi T, Ishida T, Yamamoto K, Sugiyama Y, Kawamata M. Successful tracheal intubation with the McGrath' MAC video laryngo­ scope after failure with the Pentax-AWS in a patient with cervical spine immobilization. Can ] Anaesth. 20 1 2 ; 5 9 : 1 1 54- 1 1 5 5 . 1 60. Tsujimoto T, Tanaka S, Yoshiyama Y, Sugiyama Y, Kawamata M. Successful intubation using McGrath MAC in a patient with Treacher Collins syndrome. Middle East} Anaesthesia!. 20 1 4;22: 523-525. 1 6 1 . Kido H, Komasawa N, Matsunami S, Kusaka Y, Minami T. Comparison of McGrath MAC and Macintosh laryngoscopes for double-lumen endo­ tracheal tube intubation by anesthesia residents: a prospective random­ ized clinical trial. J Clin Anesth. 20 1 5;27:476-480. 1 62. Adnet F, Racine SX, Barron SW, et al. A survey of tracheal intubation difficulty in the operating room: a prospective observational study. Acta Anaesthesia! Scand. 200 1 ;45:327-332. 1 63 . Wallace CD, Foulds LT, McLeod GA, Younger RA, McGuire BE. A comparison of the ease of tracheal intubation using a McGrath MAC® laryngoscope and a standard Macintosh laryngoscope. Anaesthesia. 20 1 5 ;70: 1 28 1 - 1 28 5 . 1 64. Pott L M , Randel G I , Straker T, Cooper RM . A survey of airway train­ ing among US and Canadian anesthesiology residency programs. j Clin Anesth. 20 1 1 ;23: 1 5-26. 1 65 . Zaouter C, Calderon J, Hemmerling TM. Videolaryngoscopy as a new standard of care. Br J Anaesth. 20 1 4; 1 1 4: 1 8 1 - 1 83 . 1 66. Bulatovic R , Taneja R . Videolaryngoscopy-for all incubations? Br } Anaesth. 20 1 5 ; 1 1 5 : 1 3 5- 1 36. 1 67. Mosier J, Joshi R, Hypes C, Pacheco G, Valenzuela T, Sakles J. The physi­ ologically difficult airway. WestJ Emerg Med. 20 1 5 ; 1 6 : 1 1 09 - 1 1 1 7.

SELF - EVALUATION QU ESTIONS 1 1 . 1 . Which o f the following statements about video-laryngo­ scopes is TRUE? A. The video-laryngoscopes facilitate the recording of the laryngoscopy. B . The technique for using the GlideScope® makes it well suited for teaching direct laryngoscopy. C. The laryngeal view obtained using the Storz Video Macintosh makes it well suited for managing the dif­ ficult airway. D. The laryngeal view is essentially the same as the line­ of-sight view. E. The images obtained using any of the video-laryngo­ scopes is hampered by fogging. 1 1 .2 . Which of the following statements about optical/ fiberoptic srylets (e.g. , the Bonfils, Shikani Optical Stylet, or Levitan FPS scope) is TRUE? A. Fiberoptic srylets should generally be used as stand­ alone tools. B. Once the tube is loaded, fiberoptic stylets have the advantage of requiring no other preparation of patient or instrument. C. Fiberoptic srylets have been proven to be effective in awake incubations.

R i g i d F i b e ro ptic a n d Video-Laryngoscopes

D . Fiberoptic stylets can be used as an adjunct to direct laryngoscopy.

B . The laryngeal view may be obscured by fogging or the presence of blood and secretions.

E. The learning curve of these devices is such that nov­ ices can be expected to have a good chance at a suc­ cessful intubation using a fiberoptic stylet.

C. Advancement of the endotracheal tube can be observed.

1 1 .3 . Which of the following regarding rigid fiberoptic laryn­ goscopes is FALSE? A. The rigid fiberoptic latyngoscopes are delicate and are easily damaged.

D. All of these devices require wider mouth opening than is required for direct laryngoscopy. E. These devices are well suited for managing difficult airways.

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Nonvisua l Intubation Techn iques Chris C. Christodoulou, Orlando R. Hung, and Jin bin Zhang

I NTRO D U CTION .

222

I NTU BAT I N G STYLETS O R G U I DES . . . . . . . . . . . . . . . .

222

LIG HTWA N DS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225 D I G ITAL I NTU BATION

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B LI N D NASAL I NTU BATION . . . . .

232

RETROG RAD E I NTU BATION . . . . . . . . . . . . . . . . . . . . . . 234 WHAT I S THE C L I N ICAL UTI LITY O F T H E RETROG RAD E I NTU BATI O N ? . . . . . . . . . . . . . . . . . . .

235

S U M MARY .

235

SELF-EVALUATIO N Q U ESTI O N S .

237

I NTRODUCTION

The high incidence of difficulty and failure, coupled with these kinds of learning curves for laryngoscopic intubation have driven the development of many alternative intubation devices and techniques, such as rigid and flexible endoscopes, video-laryngoscopes, and optical intubating stylets. All of these devices have gained a measure of popularity. Unfortunately, these devices are substantially more expensive than the Macintosh laryngoscope. Furthermore, the cleaning and ster­ ilization processes of some of these devices, such as the flexible bronchoscope, require an average of 50 to 60 minutes to com­ plete, hindering their availability and practicality in emergency airway management and in pre-hospital care (i.e., they may be "context" driven) . The challenge of visual techniques employing optical stylets and video scopes is visualization of laryngeal anatomy and the passage of the ETT through the glottic opening in the face of fogging or the presence of blood, secretions, and vomitus in the upper airway. It is precisely these kinds of difficulties that have motivated the search for nonvisual techniques using a variety of devices, such as intubating guides, light-guided intubation using the principle of transillumination, blind nasal intubation, digital intubation, and retrograde intubation, all of which have proven to be effective, safe, and simple techniques.

• Do We Sti l l Need Nonvisual Intubating

Techniq ues?

For many decades, tracheal intubation under direct vision using a laryngoscope has been considered the standard tech­ nique of intubation. Unfortunately, this approach to intuba­ tion has limitations . Difficult and failed intubation employing this technique can be as high as 2 1 %, particularly in emer­ gency situations . 1 Not surprisingly, studies have shown that considerable experience is required before a trainee becomes proficient in laryngoscopic intubation. Konrad and Mulcaster have constructed learning curves showing that a 90% prob­ ability of success requires between 47 and 57 laryngoscopic 2 intubations . ' 3

I NTU BATI NG STYLETS OR G U I DES • What Is the Esch mann Tracheal Tube

I ntrod ucer? How Does It Facilitate the Placement of an Endotracheal Tu be?

In 1 949, Macintosh4 reported the use of an introducer (gum­ elastic bougie) to facilitate orotracheal intubation under direct laryngoscopy. Using the concept of the introducer, Venn5 designed the Eschmann Introducer (Eschmann Tracheal Tube Introducer, Portex Limited, Hythe, UK) , a tube like core woven from polyester threads and covered with a resin layer. The

N o nvi s u a l I ntu bation Tec h n iq ues

Eschmann Introducer (EI) is 60 em long, with a J (coude) tip (a 35-degree angle bend) at the distal end to facilitate advance­ ment anteriorly underneath the epiglottis into the trachea and to provide tactile tracheal confirmation (Figure 12- 1A) . Centimeter markings designate the distance from the tip. The EI is often referred to as the "gum-elastic bougie" or "bougie." However, to avoid confusion, historically the "gum-elastic bougie" has been used to refer to a shorter urinary catheter made of different mate­ rial and without a curved tip.6 The EI is particularly useful when the glottic opening can­ not be clearly seen using a laryngoscope (e.g. , Grade 3 laryn­ goscopic view as described by Cormack/Lehane [C/L] ) ? Under these circumstances, the EI can be "hooked" underneath the epiglottis and advanced into the trachea. If it is correctly placed in the trachea, a subtle tactile "clicking" sensation can be felt as the tip of the EI slides over the tracheal rings while advancing it into the trachea. Furthermore, if the EI correctly enters the trachea, as it is gently advanced it will eventually be lodged (or "holdup") in a distal airway and cannot advance beyond the 30 to 35 em mark. In contrast, if it is placed in the esophagus, the entire EI can be advanced without encountering resistance. With the EI in place and positioned at 20 to 25 em at the teeth, the ETT can then be advanced over the EI into the trachea. To facilitate the advancement of the ETT over the EI, the tongue and epiglottis must be elevated by a gentle jaw lift, a jaw thrust, or preferably, by the laryngoscope already in place. If difficulty

F I G U R E 1 2- 1 . I ntu bati n g g u ides: (A) the Esch m a n n I ntrod ucer with a coude t i p at the d ista l e n d ; (B) the M u a l l e m Styl et is a s i n g l e-use 65 em l o n g tra c h ea l i ntrod ucer with a soft d i sta l coude ti p; (C) Frova I ntu bation I ntrod ucer is a n i ntu bati n g catheter with a h o l l ow l u m en and a coude t i p at the d i sta l e n d ; (D) a rem ova b l e i nter n a l m eta l stylet for the Frova I ntu batio n I ntrod ucer. The styl et i s desig ned to i n c rease the stiffness of the Frova I nt u bation I ntrod ucer to fac i l itate ETT passage over the i ntrod ucer; (E) the Endotra c h e a l Tu be I ntrod ucer i s s i m i l a r to the Esch m a n n I ntrod ucer i n size and s h a pe with a coude t i p, but it i s 1 0 em l o nger; ( F ) the A i ntree Catheter i s a l so a h o l l ow fl ex i b l e stra i g h t tu be d e s i g n ed for tracheal intu bation together with a ped iatric bro n c h oscope t h ro u g h an extra g l ottic device (EGD) such a s the LMA-Ciassic or LMA- U n iq ue; and (G) the Cook Ai rway Exc h a n g e Catheter with a n i n ner l u me n , d i sta l ports, a n d a n a d a pter a t t h e proxi m a l e n d .

persists while advancing the ETT, rotating the ETT 90 degrees counterclockwise will turn the ETT bevel facing posteriorly and minimize the risk of catching on glottic structures. 8 Following intubation, the position of the ETT is confirmed using conven­ tional methods, such as end-tidal C0 and auscultation. The 2 EI has also been used to facilitate retrograde intubation in a trauma patient,9 and placement of a tracheostomy device dur­ ing the performance of a difficult or emergency surgical airway (e.g., cricothyrotomy) . 1 0 '1 1 • What Other I ntubating G u ides or

I ntrod ucers Are Commercially Avai lable?

Since the introduction of the EI, many intubating guides of dif­ ferent sizes, shapes, lengths, and materials have been developed. All of the designs serve a function similar to the EI, but many have some additional features. (i) The Flex-Guide ET Tube Introducer (Green Field Medical Sourcing, Inc., Northborough, MA) is a single use 60 em length of flexible polyethylene tubing (5.0 mm in diameter) with a similar distal coude tip as the Eschmann Tracheal introducer. 1 2 (ii) The Muallem Stylet (VBM Medizintechnik, Sulz am Neckar, Germany) (Figure 1 2- 1 B) is a single-use 65 em long tracheal introducer with a soft distal coude tip. Unfortunately, there is no published data comparing this device to other intubating guides. (iii) Frova Intubation Introducer (Cook" Critical Care Inc., Bloomington, IN) is an intubating catheter with a coude tip at the distal end (Figure 1 2- 1 C) . 1 3 It has a hollow lumen with side ports distally; Rapi-Fit" adapters (luer lock and standard 1 5/22 mm) come with the device to permit oxygen insuffiation in the event intubation cannot be achieved. It also has a removable internal rigid metal stylet (Figure 12- 1 0) to prevent kinking and damage during shipping and to increase stiffness, facilitating tra­ cheal placement and ETT passage. The Frova Introducer has two sizes: the adult version for ETT with greater than 5 . 5 mm internal diameter (ID) and the pediatric version for ETTs 3 to 5 mm ID. (iv) Endotracheal Tube Introducer (Sun Med, Largo, FL) is similar to the EI in size and shape, but it is 1 0 em longer (Figure 12- 1 E) . This confers some advantage in employ­ ing the device as more of the device protrudes from the mouth making it easier to thread a standard 30 em adult sized ETT and capture the proximal end of the intro­ ducer. It is stiffer than the EI, conferring an advantage in guiding the ETT, but at the same time serving to empha­ size the importance of gentle maneuvers to prevent air­ way injury. There markings on the device to indicate the depth of insertion. It is a single-use disposable device, though resterilization is possible. (v) The Aintree Catheter (Cook" Critical Care, Inc., Bloomington, IN) is also a hollow flexible straight tube designed for tracheal intubation together with a pediat­ ric bronchoscope through an extraglottic device (EGO) such as the LMA-Classic or LMA-Unique. The Aintree Catheter can be advanced over a pediatric tube exchanger

223

224

Ai rway Tec h n i q ues

(vi)

(vii)

(viii)

(ix)

to obtain additional stiffness to facilitate advancement of an ETT over the pliable tube changer. Because of the hollow tube, it can also be used to oxygenate patients under difficult circumstances through the inner lumen and the distal ports after fitting the provided adaptor at the proximal end (Figure 12- 1 F) . The Cook Airway Exchange Catheter (Cook® Critical Care, Inc., Bloomington, IN) is a hollow flexible straight tube (with no coude tip bend at the distal end) designed as a tube exchanger for patients with difficult airways (Figure 12- 1 G) . It can be used to oxygenate patients under difficult circumstances through the inner lumen, distal ports, and an adapter at the proximal end. The Sheridan Tube Exchanger (Sheridan Catheter Corp., Oregon, NY) serves a similar function as the Cook Airway Exchange Catheter. The Schroeder (Parker Flex-It'" Directional Stylet) Oral/ Nasal Directional Stylet (Parker Medical, Englewood, CO) is a disposable articulating stylet that requires no bending prior to intubation (Figure 12-2) . Inserting the stylet into an ETT allows the practitioner to elevate the tip of the ETT by wrapping the index and middle fingers around the proximal tracheal tube and using the thumb to depress the proximal end of the stylet. Although the stylet is suitable for both oral and nasal intubation, it has been reported to be somewhat awk­ ward to use and the curvature created is not at the tip, but rather over the distal half of the tube. 14 However, it has been reported to be effective for difficult as well as blind intubations. 1 5 Portex intubation stylet (SIMS Portex Ltd, Hythe, Kent, UK) is available in outer diameter sizes ranging from 2.2 to 5 . 0 mm. These stylets can be inserted into a variety of endotracheal tubes. Blind awake orotracheal intubation has been successfully performed utilizing a stylet loaded into an ETT, in a patient with a laryngeal carcinoma and ankylosing spondylitis. 16 Guided tactile probing is used to direct the ETT-stylet unit into the trachea.

F I G U R E 1 2-2. The S c h roeder (Pa rker Fl ex-l t'M Di rectio n a l Styl et) Ora l/ N a s a l D i recti o n a l Styl et. E l evation of the t i p of the ETI c a n be a c h i eved by wra pp i n g the i nd ex a n d m id d l e fi n g e rs a ro u n d the prox i m a l tra c h e a l tube a n d using the th u m b to de press the p roxi­ mal end of the styl et (a rrow) .

• Is There Any Clinical Evidence to Su pport

the Widespread Use of These I ntubati ng I ntrod ucers?

Over the last several decades, numerous studies have reported the effectiveness and safety of employing an EI to facilitate tracheal intu b ation in patients with d'ffi 1 cuI t I aryngoscopy. 17-20 The EI has been well accepted by most practitioners in the United Kingdom, and it continues to play an important role in the management of the difficult laryngoscopic intubation. According to a recent survey in the United Kingdom, 1 00% of the respondents reported the use of the EI as their technique of choice when faced with an unanticipated difficult laryngo­ scopic intubation. 2 1 Though primarily a device used by anesthe­ sia practitioners in the past, over the past decade this relatively inexpensive and simple device has found its way to the hands of emergency practitioners and pre-hospital health care practitio. 22-24 A teI ep hone ners as a standard airway management adJUnct. survey of emergency departments in England revealed that 99o/o of respondents stocked the EI on their difficult airway carts. 2 5 Following a review of the evidence, the Difficult Airway Society Guidelines for Management of the Unanticipated Difficult Intubation in the United Kingdom recommend the use of the EI as the initial device to facilitate a difficult laryn­ goscopy. 26 Many authorities recommend that this device be a standard piece of equipment for every laryngoscopic intubation. While the EI has been widely accepted as a useful tracheal intubation adjunct, other types of introducers bearing similar features do not share the same popularity. This may be due to a paucity of clinical evidence supporting their use compared to the EI. In addition, most of these new intubating guides and stylets are disposable devices intended for single use and perhaps less cost-effective than the reusable EI. ·

·

• What Are the Potential Limitations of These

I ntubating G u ides and I ntrod ucers?

The popularity of the EI rests on its simplicity, ease of use, high success rates, and relatively few complications. However, it does have limitations. The much-anticipated "clicks" and the "holdup" as described by many may prove elusive. The appreciation of clicks is par­ ticularly subtle in many patients. In 1 988, Kidd et al. 27 stud­ ied the reliability of these signs. They found that "holdup" was observed in 1 00% of tracheal EI placement, whereas "clicks" were appreciated in only 90%. Importantly however, neither was observed in any of the 22 esophageal placements. It is also possible that "holdup" might occur with esophageal placement of the EI in cases of esophageal stenosis, pharyngeal pouch or diverticulum, or with cricoid pressure, although one would anticipate these occurrences would be rare. Practitioners should be aware of these limitations, particularly where "holdup" can occur without the presence of "clicks." It is the opinion of the author (ORH) that the probability of feeling the "clicks" with EI placement into the trachea depends largely on the angle of insertion of the EI relative to the trachea. It is unlikely that the tip of the EI will "rub" against the tracheal rings if the EI is advancing into the trachea from a more vertical position. It is also related to the degree to which the EI contacts other soft

N o nvi s u a l I ntu bation Tec h n iq ues

tissues in the airway (e.g., tongue or lip) insulating against the transmission of the subtle tactile sensation. Although complications are rare with these devices, they tend to occur when they are used improperly. Soft tissue lacerations, esophageal perforation, and tracheo-bronchial tree injuries have been reported with aggressive insertion of the EI and forceful "railroading" of the ETT over the EI. 2 8-30 The incidence of these complications can be minimized by employing a gentle advance­ ment technique, and using the laryngoscope to move soft tissues out of the way to improve the angle of insertion of the ETT over the EI. Tip detachment has also been reported. Gardner et al.31 reported a detachment of the tip of the EI following its withdrawal. The tip was initially identified just above the bifur­ cation of the trachea, although it was later documented to have moved into the right middle lobe bronchus. Manually checking the integrity of the tip of the EI prior to use is recommended. • Are There Any Clin ical Differences Between

the El and Other I ntrod ucers with Identical Features?

Inspired by the simplicity and effectiveness of the EI, many newer introducers (e.g. , the Frova Intubation Introducer and the Sun Med Endotracheal Tube Introducer) share similar char­ acteristics such as the J (coude) tip at the distal end. By and large, these newer devices are made of different materials and are designed for single use. The Frova Intubation Introducer and the Cook Airway Exchange Catheter are hollow intubat­ ing introducers that permit urgent oxygenation and ventilation should the tracheal tube fail to advance into the trachea over the introducer. In addition to the "tracheal clicks" and "holdup" of the introducers during the insertion into the trachea, an aspi­ ration test using a self-inflating bulb (SIB; also known as an Esophageal Detection Device [EDD]) can also be used with the hollow intubating introducers to further confirm tracheal placement. Tuzzo et al.32 reported that a prompt and complete reinflation of the SIB failed to occur when the hollow intu­ bating introducer was placed accidentally into the esophagus with 1 00% sensitivity and at a 3 . 5 % false positive rate. While these newer devices appear to function similarly to the EI in facilitating tracheal intubation, they may not have comparable success rates. Using a simulated C/L Grade 3 laryngoscopic view in a manikin, a comparative study showed that successful placement of the Frova Introducer (65%) and the EI (60%) was significantly higher than with the Portex Introducer (8%) . 1 2 A separate experiment also revealed that the peak force exerted by the Frova and Portex introducers was two to three times greater than that which could be exerted by the EI, suggesting that placement of the single-use introducers may be more traumatic.

LIGHTWAN DS • What Is a Lightwand? How Does It Help with

the Placement of an Endotracheal Tu be?

The technique of transillumination using a lightwand (lighted­ stylet) was first described by Yamamura et al.33 in 1 959 with nasotracheal intubation. The lightwand employs the principle

F I G U R E 1 2-3. (A) When the t i p of the ETI with the l i g htwa n d i s p l a ced at the g l ottic o pe n i n g u n d e r d i rect l a ry n goscopy, a wel l ­ defi ned c i rc u m scri bed g l ow (a rrow) i n t h e a nterior n e c k j u st below the thyroid pro m i nence ca n be rea d i l y see n . (B) When the t i p of the e n d otra c h e a l t u be is p l a ced in the eso p h a g u s u n d e r d i rect l a ryngoscopy, tra n s i l l u m i nation is poor a n d the tra n sm itted g low is d iffu se in the a nte rior neck a n d can not be seen ea s i l y u n d e r a m bi­ ent l i g ht i n g condition.

of transillumination of the soft tissues of the anterior neck to guide the tip of the lightwand, and the mounted ETT, into the trachea. It also takes advantage of the anterior (superficial) loca­ tion of the trachea relative to the esophagus. When the tip of the ETT/lightwand (ETT/LW) combina­ tion enters the glottic opening, a well-defined circumscribed glow can be readily seen slightly below the thyroid prominence (Figure 12-3A) . However, if the tip of the ETT/LW is in the esophagus, the transmitted glow is diffuse and cannot be read­ ily detected under ambient lighting conditions (Figure 12-3B) . I f the tip o f the ETT/LW i s placed i n the vallecula, the light glow is diffuse and appears slightly above the thyroid promi­ nence. Using these landmarks and principles, the practitioner can guide the tip of the ETT easily and safely into the trachea without the use of a laryngoscope. • Are All Lig htwands the Same?

Through the 1 970s and 1 980s, many versions of a lighted sty­ let had been introduced, including the Fiberoptic Malleable Lighted Stylet (Metropolitan Medical Inc. , Winchester, VA) , Fiberoptic Lighted-Intubation Stylet (Anesthesia Medical Specialties, Santa Fe, CA) , Lighted Intubation Stylet (Aaron Medical, St. Peterborough, FL) , Flexilum'M (Concept Corporation, Clearwater, FL) , Tubestat'M (Xomed, Jacksonville, FL) (Figure 12-4) , and Imagica Fiberoptic Lighted Stylet (Fiberoptic Medical Products, Inc., Allentown, PA) . Some of these devices have proven to be effective and safe in placing an ETT both orally and nasally.306 Even though favorable results have been reported with these devices, substantial limi­ tations have been identified: ( 1 ) poor light intensity; (2) short length, limiting the use of the lightwand device to a short or cut ETT; (3) absence of a connector to secure the ETT to the

225

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Ai rway Tec h n i q ues

F I G U R E 1 2-4. Co m m e rc i a l l y ava i l a b l e l ig htwa n d s : (A) F l exi l u m'M, ( B) Tu bestat'M, a n d (C) Fibero ptic M a l l e a b l e Lig hted Stylet.

lighrwand device; (4) rigidity of the lighrwand, hampering use of the devices with other techniques, such as light-guided nasal intubation; and (5) most lighrwands were designed for single use, increasing the cost per intubation. For these reasons and others, intubation using a lighrwand did not receive widespread popularity until the introduction of the Trachlight'M (TL) (Laerdal Medical, Wappingers Falls, NY) device in 1 99 5 . • What Are Some of the U n ique Characteristics

of the Trachlight™ Compared to Other Lig htwand Devices?

The TL has a long and flexible wand with a retractable metal wire stylet and an improved light source. These features add flexibility, broaden the utility of the device for both oral and nasal intubation, make intubation easier, and permit the evaluation of the position of the tip of the ETT after intu­ bation. To date, the TL has been the most popular and well­ studied of the lightwands. Although the TL is no longer manufactured, a new version of the lightwand similar to the TL is being developed.37·38 One of the authors (ORH) of this chapter was involved in the original design and development of the TL. For these reasons, much of the following discussion reflects this experience and bias toward the TL. Nevertheless, the concept and principles of intubation using transillumina­ tion is applicable to all other lightwands. The (TL) consists of three parts: a reusable handle, a flexible wand, and a stiff retractable wire stylet (Figure 12-5) . The power control circuitry and three triple "A" alkaline batteries are encased in the handle. A locking clamp located on the handle accepts and secures a standard 1 5-mm ETT connector. The stylet or "wand" consists of a durable, flexible plastic shaft with a bright light bulb affixed at the distal end, permitting intubation under ambient lighting conditions. After 30 seconds of illumi­ nation, the light bulb blinks to minimize heat production and provide a convenient reminder of elapsed time. Ensuring that the tip of the stylet is inside the distal tip of ETT enhances its heat safety profile. An animal study conducted in 1 998 confirmed an absence of heat-related tissue histopathological changes suggesting that thermal injury following the use of the TL is unlikely.39

F I G U R E 1 2-5. The Trach l ig ht'M consists of th ree pa rts: a h a n d l e, a fl ex i b l e wa nd, a n d a stiff retracta b l e stylet w i re. With the TL i n p l a ce, the ETI-TL u n it is bent at a 90-deg ree a n g l e j u st p roxi m a l to the cuff of the t u be i n the s h a pe of a "fi e l d hockey stick:'

A rigid plastic connector with a release arm at the proximal end of the TL handle allows adjustment of the wand along the handle and into the ETT when the release arm is depressed. Enclosed within the wand is a stiff but malleable, retractable wire stylet. When the stiff wire stylet is retracted, the wand becomes pliable, permitting the ETT to advance easily into the trachea. This may well be the most important feature of this lightwand device, since it significantly improves its ease of use and intubation success rate. The retractable wire stylet stiffens the wand sufficiently so that it can be shaped in the form of a "field hockey stick" (Figure 1 2-5) . This configuration directs the bright light of the bulb against the anterior wall of the larynx and trachea. In addi­ tion, the "hockey stick" configuration enhances maneuverabil­ ity during intubation and facilitates the placement of the ETT through the glottic opening. However, once through the glot­ tis, the "field hockey stick" configuration can impede further advancement of the tube into the trachea. Retraction of the stiff wire stylet produces a pliable ETT-TL unit, permitting its advancement into the trachea until the transilluminated glow reaches the sternal notch, a point known to be at the level of the mid-trachea. • H ow Do Yo u Prepare the Trach l i g ht™

Device?

As with any intubation technique, regular use of a lighrwand improves the practitioner's performance and intubation success rates, and reduces the risk of complications. Lubrication of the internal wire stylet of the wand using silicone fluid (Endoscopic Instrument Fluid, ACMI, Southborough, MA) ensures its easy retraction during intuba­ tion. The wand should also be lubricated with the same silicone fluid to facilitate retraction of the wand following the ETT placement. The rail gear of the TL handle should always be inspected for missing fragments (prior to loading of the stylet, after retraction of the stylet) .4° Cutting the ETT to a length

N o nvi s u a l I ntu bation Tec h n iq ues

of 26 em is recommended to facilitate maneuverability of the ETT-TL during oral tracheal intubation. The wand is then inserted into the ETT and the tube attached to the handle. The length of the wand is adjusted by sliding the wand along the handle to position the light bulb close to, but not protruding beyond, the tip of the ETT. With the TL in place, the ETT-TL unit is bent to a 90-degree angle just proximal to the cuff of the tube in the shape of a "field hockey stick" (Figure 1 2-5) . Even though the degree of bend should be individualized to the patient, a 90-degree angle generally makes the intubation considerably easier and projects the maximum light intensity toward the surface of the skin as the device traverses the glottis and trachea, producing a well-defined exterior circumscribed glow. If the TL is bent to 45 degrees, the maximum light inten­ sity will be directed down the trachea. For obese patients or patients with short necks, a more acute bend (greater than 90 degrees) provides better transillumination. Although it is the author's experience that the recommended length of the TL from bend to tip of 6.5 to 8 . 5 em is suitable for most patients, some investigators have suggested that the length from bend to tip is best established by matching it to the patient's thyroid prominence-to-mandibular angle distance.41

F I G U R E 1 2-6. Th i s rad iological fi l m of the u pper a i rway s h ows that u n d e r a nesthesia a n d with the patient l y i n g s u p i ne, the ton g u e fa l l s posteriorly, p u s h i n g t h e e p i g l otti s (E) a g a i n st the pos­ terior p h a ryngeal wa l l (P)

• How Do You Use the Trachlight™ to Perform

Tracheal I ntubation?

Although the practitioner usually stands at the head of the table or bed during lightwand intubation, it is possible to employ this technique from the front or side of the patient, in the pre­ hospital environment for instance. When the head is in the sniff­ ing position, the epiglottis is in close contact with the posterior pharyngeal wall making it more difficult for the TL to advance behind the epiglottis. It is preferable that the patient's head and neck be positioned in a neutral or slightly extended position. In most cases, patients can be intubated easily under ambient lighting conditions.42 In very thin patients, the light intensity is so bright that it is possible to mistakenly interpret an esopha­ geal intubation as an intratracheal placement. It is therefore recommended that intubations using the TL in otherwise nor­ mal individuals be carried out under ambient light. Dimming room lights may be advantageous in obese patients, patients with thick necks or dark skin, or when the technique is being learned. In settings where controlling the ambient lighting is not possible (e.g., pre-hospital) , it may be helpful to shade the neck with a towel or a hand. Denitrogenation of the patient should precede all light-guided intubations. In an unconscious patient lying supine, the tongue falls posteriorly, pushing the epiglottis against the posterior pha­ ryngeal wall (Figure 12-6) . In order to have clear access to the glottic opening during intubation, it is necessary for the practi­ tioner to grasp the jaw and lift it upward using the thumb and index finger of the nondominant hand. This lifts the tongue and epiglottis away from the posterior pharyngeal wall to facilitate placement of the tip of the ETT posterior to the epiglottis and into the glottic opening (Figure 12-7) . The ETT-TL unit is then inserted into the midline of the oropharynx. The midline posi­ tion of the ETT-TL is maintained while the device is advanced gently in a rocking motion along an imaginary anterior-posterior

F I G U R E 1 2-7. Th i s rad iological fi l m of the u pper a i rway s h ows that the jaw or m a n d i b u l a r (M) l ift by the n o n d o m i n a n t h a n d (H) ca n e l evate the to n g u e a n d epig l otti s (E) off the posterior p h a ryn­ g e a l wa l l (P), thus provi d i n g a clear passage for the e n d otra c h e a l t u be t o e nter the g l ottic o pe n i n g .

arc. When resistance to cephalad rocking of the handle is felt, the ETT-TL handle should be "rocked" forward (toward the feet) and the tip redirected toward the laryngeal prominence using the glow of the light as a guide. A faint glow seen above the laryngeal prominence indicates that the tip of the ETT-TL is located in the vallecula. When the tip of ETT-TL enters the glot­ tic opening, a well-defined circumscribed glow can be seen in the anterior neck slightly below the laryngeal prominence (Figure 12-8) . Retracting the inner stiff wire stylet approximately 1 0 em makes the ETT-TL tip more pliable, permitting advancement into the trachea with reduced risk of trauma. The ETT-TL is then advanced until the glow begins to disappear at the sternal notch indicating that the tip of the ETT is approximately 5 em above the carina in the average adultY Following release of the locking clamp, the TL wand can be removed from the ETT.

227

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Ai rway Tec h n i q ues

F I G U R E 1 2-8. A brig ht, wel l-defi ned, c i rcu m scri bed g low (a rrow) is seen below the thyroid pro m i nence when the ETI-TL enters the g l ottic open i n g .

Occasionally, the circumscribed glow cannot be readily seen in the anterior neck due to anatomical features such as mor­ bid obesity or a short neck. Neck extension as described above may be helpful. Retraction of the breast or chest wall tissues together with "spreading" of the tissues around the trachea by an assistant enhances transillumination of the soft tissues in the anterior neck. Dimming the ambient light is seldom required. Occasionally, following retraction of the stiff wire stylet, the tip of the tube and lighrwand can "hang up" on laryngeal structures, the cricoid ring, or a tracheal ring and cannot be advanced into the trachea readily. This is likely due to the fact that when an ETT is loaded along its natural curvature onto the TL, the tip of the ETT has a tendency to bend anteriorly upon retraction of the stiff internal stylet. While maintaining tube tip contact with the anterior airway, the practitioner should rotate the ETT-TL 90 degrees or more to the right or the left side permitting the tip of the ETT to alter the orientation of the tube tip perhaps enhancing the chance that the ETT will enter the trachea. Alternatively, immersing the ETT in warm saline solution prior to tracheal intubation will reduce its stiffness and the memory of its natural curvature. In addition, reverse loading of the ETT onto the TL. may minimize the tendency of the ETT tip to bend anteriorly while retracting the internal stiff stylet of the TL. The combination of softening and reverse loading of the ETT has been shown to overcome the problem of "hang up" during intubation with the TL.44 • Can the Trachlight� be Used for Nasotracheal

I ntu bation? How Do You Use the TL to Perform a Nasotracheal l ntu bation?

In contrast to other commercially available lighrwands, once the stiff internal wire stylet is removed, the wand of the TL becomes pliable and able to facilitate a light-guided nasotracheal intuba­ tion. When used with a nasal RAE (Ring, Aldair, and Elwyn) ETT, the inner wire stylet should be inserted halfway (about 1 5 em) to allow unbending of the proximal curvature of the nasal

F I G U R E 1 2-9. For l i g ht-g u ided n a s a l i ntu bation u s i n g the Trach l ig ht™, the i nte r n a l w i re stylet is genera l ly removed so that the wa nd of the TL becomes p l i a b l e to fac i l itate na sotra c h e a l i ntu­ bati o n . However, if a nasa l RAE tube i s used, the proxi m a l c u rvatu re of the n a s a l RAE Tra c h e a l Tu be wi l l bend the p l i a b l e wa n d of the TL (B), m a k i n g it d iffic u l t to control the t i p of the tra c h e a l t u be d u ri n g intu bati o n . W h e n the T L i s u sed with a nasa l R A E ETT, the w i re sty­ l et (a rrow) s h o u l d be retracted o n l y h a lfway (a bout 1 5 em) to a l low u n be n d i n g of the proxi m a l cu rva tu re of the nasal RAE t u be (A) to fac i l itate l i g ht-g u ided nasal i n t u bation.

RAE tube (Figure 12-9) . Application of a vasoconstricting nasal spray to the nasal mucosa prior to intubation may help to mini­ mize bleeding. The ETT-TL should be immersed in a bottle of warm sterile water or saline to soften the ETT and reduce the risk of mucosal damage during nasal intubation. Water­ soluble lubricant is applied to the nostril to facilitate entry of the ETT-TL through the nose. As with oral intubation, a jaw lift during intubation will elevate the tongue and epiglottis away from the posterior wall of the pharynx (see Figure 1 2-7) , facilitating the placement of the tip of the ETT behind the epiglottis and into the glottic opening. The TL is switched on once the tip of the ETT-TL has advanced into the orophar­ ynx, positioned in the midline, and advanced gently using the light glow as a guide. A faint glow seen above the laryngeal prominence indicates that the tip of the ETT-TL is located in the vallecula. A jaw lift and slight withdrawal of the ETT-TL will help to elevate the epiglottis and enhance the passage of the ETT-TL under it. When the ETT-TL enters the glottic opening, a well-defined circumscribed glow is seen in the ante­ rior neck just below the thyroid prominence (Figure 12- 1 0) . Following the release o f the locking clamp, the T L is withdrawn from the ETT. Correct tube placement should be confirmed using end-tidal C0 and auscultation. 2 • What Are the Common Problems with

a Blind or Light-G u ided Nasotracheal I ntubation? How Do You Overcome These Problems?

Due to the natural curvature of the ETT, the tip of the tube often goes posteriorly into the esophagus during a "blind" or light-guided nasal intubation, despite external posterior

N o nvi s u a l I ntu bation Tec h n iq ues

F I G U R E 1 2- 1 0. D u r i n g na sotra c h ea l i ntu bation, when the ETI-TL enters the g l ottic o p e n i ng, a wel l -defi n ed c i rc u m scri bed g l ow (a rrow) i s seen in the a nterior neck j u st below the thyroid pro m i n e nce.

pressure on the thyroid cartilage. To elevate the tip of the ETT anteriorly during intubation, it is sometimes necessary to flex the neck of the patient while advancing the ETT-TL slowly. In the event that flexing the neck of the patient is contraindicated, inflating the ETT cuff with 1 5 to 20 mL of air will help to elevate the ETT tip and align it with the glottis during intuba­ tion.45•46 Alternatively, the use of a directional-tip tube, such as an Endotrol'" tube (Mallinckrodt Critical Care, Inc. , St. Louis, MO), flexes the tube tip anteriorly and into the glottisY In certain circumstances (e.g., tube tip impingement in the pos­ terior nasopharynx) , nasotracheal intubation using the TL can be performed safely with the stiff, internal stylet in place.48 1his technique may be associated with fewer head-neck manipula­ tions and deliver better control of the tip of the ETT. • What Are the Limitations of the Lig htwand

I ntubating Technique?

The lightwand intubating technique requires transillumination of the soft tissues of the anterior neck without visualization of the laryngeal structures. Therefore, lightwand should not be used in patients with known abnormalities of the upper airway, such as tumors, polyps, infection (e.g., epiglottitis, retropha­ ryngeal abscess) , and trauma to the upper airway, or if there is a foreign body in the upper airway. In these cases, alternate intubating techniques using direct or indirect vision, such as bronchoscopic intubation, should be considered. Lightwand should also be used with caution in patients in whom transil­ lumination of the anterior neck may not be adequate, such as patients who are grossly obese or with a limited neck exten­ sion. However, these contraindications and precautions must be weighed in the light of the urgency of achieving a patent airway in any patient whose ventilation may be compromised and urgent intubation is required. Clearly, this light-guided technique should not be attempted with an awake uncoopera­ tive patient unless a bite block is used to prevent damage to the device or injury to the practitioner.

Since its introduction in 1 995, the TL has been used extensively in many countries. While the potential risks of damage to the glottic opening during tracheal intubation using a "nonvisual" intubating technique is real, there have been no serious complications reported. Aoyama et al. used a nasally placed bronchoscope to visualize the airway during TL intu­ bation. They reported that the epiglottis may be pushed into the laryngeal inlet by the ETT-TL during a TL intubation.49 Fortunately, the epiglottis usually spontaneously returned to its correct position. They also reported that structures around the glottic opening, including the epiglottis and the arytenoids, were transiently displaced during the placement of the ETT using the TL. The investigators concluded that there are poten­ tial risks of laryngeal damage in addition to the down folding of the epiglottis during the ETT placement using the TL, but such occurrences do not appear to cause permanent damage. Other investigators have identified a reduced incidence of sore throat in patients intubated using the TL compared to laryngo­ scopic intubation.42 Intubation using a lightwand device has other potential risks. Stone et al.50 reported disconnection of the light bulb from a lightwand requiring retrieval from a major bronchus. However, the lightwand device employed in this instance (Flexilum'") was not designed or recommended for tracheal intubation. A later version of the same device solved the problem of bulb loss into the trachea by encasing stylet and bulb in a tough plastic sheath (Tubestat'") . In contrast to the older lightwand devices, it is extremely unlikely that the light bulb will be detached from the TL, since the light bulb is firmly attached to the durable plastic sheath of TL. In fact, since its introduction in 1 99 5 , there have been n o reported cases o f detached light bulb from the TL. Although rare, subluxation of the cricoarytenoid car­ tilage has been reported in a study using an older version of a lightwand (Tubestat'") .51 However, with the retractable wire stylet, the risk of damaging the arytenoid cartilage during TL intubation should be low. • Is There Any Clinical Evidence to Suggest

That the Lig htwa nd Is an Effective and Safe I ntubating Device?

A large clinical study involving 950 elective surgical patients conducted to determine the effectiveness and safety of orotra­ cheal intubation using either the TL or direct-vision intubation using a laryngoscope,42 showed a statistically significant dif­ ference in the total intubation time between the groups ( 1 5.7± 1 0 . 8 vs. 1 9 .6±23.7 seconds for TL and laryngoscopy, respectively) . However, such a small difference is probably of little clinical importance. There was a 1% failure rate with the TL and 92% success rate on the first attempt, compared with a 3% failure rate and an 89% success rate on the first attempt using the laryngoscope. There were significantly fewer trau­ matic events and sore throats in the TL group compared to laryngoscopy patients. Tsutsui et at5 2 reported similar findings in a study with 5 1 1 patients. TL intubation was highly success­ ful (99%) with the majority of the successful intubations (93%) being accomplished after one attempt. Unsuccessful intubation even at the third attempt occurred in only three patients (1 %) .

229

230

Ai rway Tec h n i q ues

In 1 99 5 , Hung et al.53 reported the effectiveness ofTL intu­ bation in 265 patients with a "difficult" airway (206 patients with a documented history of difficult intubation or anticipated difficult airways and 59 anesthetized patients with an unantici­ pated failed laryngoscopic intubation) . Tracheal intubation was successful in all patients except two in the anticipated difficult laryngoscopic intubation group. Apart from minor mucosal bleeding (mostly from nasal intubation) , no serious complica­ tions were observed in any of the study patients. The results of this study indicate that TL is an effective technique for placement of ETTs (nasally and orally) for patients with both anticipated or unanticipated difficult airways. Other investiga­ tors have reported successful use of the TL in patients with a difficult airway. These include patients with a history of limited mouth opening,54 cervical spine abnormality,55 Pierre-Robin syndrome,56 and cardiac patients with a difficult airway. 57 • What Are Some of the Potential Uses of the

Trachlight™?

Tracheal intubation can fail with TL as well as with the laryn­ goscope. However, one study of 950 patients showed that all TL failures were resolved with direct laryngoscopy.42 Similarly, all failures of direct laryngoscopy were resolved with TL. These results suggest that a tracheal intubation success rate approach­ ing 1 00% can be achieved by combining the techniques. This combined approach may be particularly useful when an unanticipated Cormack/Lehane (C/L) Grade 3 laryngoscopic view is encountered? Instead of using a styleted ETT with a 90-degree bend, one might employ an ETT-TL with the same bend. Under direct laryngoscopy, the tip of the ETT-TL can be "hooked" under the epiglottis. A well-defined circumscribed glow seen in the anterior neck slightly below the laryngeal prominence indicates that the tip of the ETT is placed at the glottic opening. In the event that such a glow is not seen, the ETT-TL can be repositioned until it can be seen. The effective­ ness of this combined technique has been reported by Agro et al. 58 In this study, the investigators successfully performed tracheal intubation in all 350 surgical patients studied with a simulated difficult airway using a combined laryngoscope/TL approach. The TL has been combined successfully with other intu­ bating techniques including intubation through the LMA­ Classic'M,47•59 use in conjunction with the intubating LMA (LMA-Fastrach'") ,60 with the Bullard laryngoscope,6L62 and with a retrograde intubating technique.63 The TL has been shown to be useful in identifYing the intra­ tracheal position of the ETT tip during percutaneous dilational tracheotomy.64 The TL wand without the stiffening wire is passed through the in situ ETT matching the length numbers on the ETT to position the TL tip at the ETT tip. This simple technique may help to prevent inadvertent punctures of the ETT and/or its cuff ensuring that adequate ventilation and oxy­ genation can be reinstituted during the percutaneous procedure if required. This technique is inexpensive and minimizes the risk of damaging expensive equipment ordinarily used during such procedures such as the flexible bronchoscope. Used prop­ erly, it is possible that this simple light-guided technique can

also be used to accurately determine when the tip of the ETT is above the surgical tracheotomy site as the tube is pulled back during surgical tracheotomy.

DIGITAL I NTU BATION • What Is Digita l I ntubation? When Was It

I ntrod uced?

Airway management has been revolutionized by the abundance of EGOs that not only facilitate effective ventilation but also aid tracheal intubation. Despite these advances, certain situations may make the blind insertion of an ETT into the trachea using the digits of the hand (digital intubation or tactile orotracheal intubation) a suitable alternative method of securing an airway. It is believed that this technique was first described by Herho!t and Rafn in 1 796 in drowning victims. It surfaced as a viable method of intubation in the emergency medicine lit­ erature in the mid- 1 980s. 65·66 Blind digital intubation has also been used to establish an airway during neonatal resuscitation67 and as an adjunct in blind nasotracheal intubation.68 • What Are the Indications for Digital

I ntubation?

The skill levels of the practitioner, coupled with previous expe­ rience in using the technique of blind digital intubation are important prerequisites for success. The importance of prac­ ticing this technique in nonemergency situations cannot be overemphasized. The risk of infectious disease transmission must always be borne in mind. Awake patients with an intact gag reflex are not suitable for this technique. Muscle paralysis may be helpful in certain situations. The following list briefly describes the clinical situations where blind digital intubation may be used to establish a patent airway: (a) Inadequate access to a patient's airway that prevents stan­ dard laryngoscopic techniques from being used. (b) Lack or failure of other airway management devices. (c) Inability to secure an airway with laryngoscopic techniques or EGOs. (d) In the setting of cervical spine instability in an unconscious patient. (e) When blood, secretions, vomitus, or pus make adequate visualization of the glottis impossible. • How Do You Perform Digita l Intubation?

The skilled practitioner ensures that an oxygen source, rescue airway devices, suction, and emergency drugs are immediately at hand. In-line immobilization should be performed in the setting of cervical spine instability. Cricoid pressure should be applied where clinically indicated. Although digital intubation can usually be performed without other adjuncts (Figure 12-1 1) , the classic description o f blind digital intubation requires a mal­ leable stylet to be inserted into the ETT.69 The ETT is then bent into a shape such that it can elevate the epiglottis and enter the trachea. Alternatively, as the authors believe, an intubating guide (e.g., the El) together with an appropriately sized ETT

N o nvi s u a l I ntu bation Tec h n iq ues

F I G U R E 1 2- 1 1 . M a n i k i n d e m o n stration of d i g ita l intu bation with­ out u s i n g a stylet or i n t u bati n g g u ide: the i ndex and m i d d l e fi n g e rs of the n o n d o m i n a n t h a n d a re i n serted i nto the mouth. O n ce the e p i g l ottis (E) i s p a l pated by the middle fi n g e r (M), it i s l ifted i n an a nte rior d i rection. The i n d ex fi n g e r (I) of the n o n do m i n a nt h a n d is then flexed t o g u id e the tra c h e a l tu be u n d e r the e p i g l otti s a n d i nto the trachea.

is a simpler technique. The advantage of this latter technique is that it is easier to guide an EI through the glottic opening, and then railroad the ETT into the trachea than it is to place a stylet-ETT combination in the trachea. The intubating guide has a small external diameter and is easily manipulated with the fingers to enable passage through the vocal cords. In addition, the clicks felt as the intubating guide (e.g., EI) advances over the tracheal rings combined with "holdup" will assist in confir­ mation that the EI has entered the trachea. The ETT with the malleable stylet is rigid and perhaps more likely to cause blunt trauma to the airway structures, especially if repeated manipu­ lation is necessary for successful entry into the trachea. To perform the procedure: (a) The patient's head should be placed in the sniffing position as for standard laryngoscopic intubation except in situa­ tions where cervical instability exists. (b) The practitioner stands or kneels adjacent to the patient (facing the patient's head) so that the nondominant side of the intubator is closest to the patient (Figure 12- 1 2) . (c) I f available, an assistant can grasp and pull the tongue for­ ward using gauze. This maneuver helps to lift the epiglot­ tis anteriorly and makes palpation of the structures of the upper airway easier. (d) The practitioner then places the index and middle fingers of the nondominant hand into the patient's mouth. Once the epiglottis is palpated by the middle finger, it is lifted in an anterior direction. (e) The intubating guide is then guided into the mouth along the palmar surface of the index finger of the nondominant hand. (f) The index finger of the nondominant hand is then flexed to steer the intubating guide under the epiglottis and into the trachea (Figure 12- 1 2) . Occasionally the middle finger

F I G U R E 1 2- 1 2. D i g ita l intu bation u s i n g a n intu bati n g g u ide: to v i s u a l ize the tech n i q u e of d i g ita l i ntu bation, a fl exi b l e bro n c ho­ scope was p l a ced t h ro u g h the right nostri l i nto the n a s o p h a rynx of the patient. D u ri n g the d i g ita l i ntu bation, the i n dex and m i d d l e fi n g e rs o f t h e n o n d o m i n a n t h a n d a re i n serted i nto the m o u t h . A s s h own i n the m o n itor (a nd the e n l a rged i n sert), o n c e the e p i g l ot­ tis is pal pated by the m i d d l e fi n g e r (M), it is l ifted in a n a nterior d i rectio n . The i ndex fi n g e r (I) i s then flexed to g u id e the i ntu bati ng g u id e (G) under the e p i g l otti s and i nto the trachea (T)

of the nondominant hand lifting the epiglottis has to be moved slightly laterally to allow successful passage of the intubating guide. (g) The clicks on the tracheal rings and holdup of the intubat­ ing guide on the lower bronchial tree serve as indicators of correct tracheal placement. (h) The ETT is then railroaded over the intubating guide into the trachea. Maintaining anterior displacement of the epi­ glottis facilitates ETT passage. (i) Confirmation of successful tracheal intubation should be determined by end-tidal C0 detection. 2 • Can Digital Intubation be Performed on a

Child?

Although the principles and techniques of digital intubation are similar, digital intubation can readily be performed without the use of a stylet or the EI in children. Hancock et al. 67 have employed this technique during neonatal resuscitation and accidental extubation scenarios. Digital intubation of neonates and infants can be considered in situations where direct laryn­ goscopic techniques have failed, airway equipment failure has occurred, for meconium aspiration in the neonate, or during transport when inadequate access may preclude conventional techniques. • What Are the Lim itations of Digital

I ntubation?

Although digital intubation is a simple and easy to learn tech­ nique, it is difficult to perform when the epiglottis cannot be identified or felt during intubation. This is particularly true for

23 1

232

Ai rway Tec h n i q ues

the patients who are excessively tall or with a full set of maxil­ lary incisors and a small mouth opening. The procedure can also be difficult to perform if the practitioner has short or large fingers in relation to the patient's anatomy. To minimize the risk of inj ury to the practitioner's fingers, digital intubation is generally contraindicated for patients who are awake and uncooperative. However, in emergency situa­ tions when limited equipment is available, a digital intubation may be an option with a bite block in place.

BLI N D NASAL I NTU BATION • What Are the Ind ications for Blind Nasal

Intubation?

The technique of blind nasal intubation was first popularized by Sir Ivan Magill and Stanley Rowbotham in the 1 920s. This method of tracheal intubation has proved life-saving in many difficult airway situations, and continues to be a useful adjunct in the difficult airway armamentarium.70 It can be performed in patients who are unable to lie flat, and maintenance of spon­ taneous ventilation facilitates blind nasal intubation requiring minimal neck manipulation. The experience and skill of the practitioner are key determinants for success with this tech­ nique. Indications for blind nasal intubation include: (a) elective oral, pharyngeal, and dental surgery (b) when the oral route is difficult or impossible (e.g., limited mouth opening, temporomandibular joint diseases, or severe masseter spasm) (c) difficult airway-elective or unanticipated • What Are the Contra ind ications of Blind

Nasal I ntubation?

The following may contraindicate blind nasal intubation: (a) inadequate experience or skill of the practitioner (b) base of the skull cranial fractures (c) severe maxillofacial fractures with distorted nasal or mid­ face anatomy (d) known or suspected nasal obstruction secondary to pathol­ ogy (e.g., massive nasal polyps or tumors) (e) bleeding diathesis secondary to hematological disease or anticoagulant medication (f) severe laryngeal trauma or infection • Which Nostril Should be Used for Blind Nasal

I ntubation?

As most practitioners are right-handed, naturally, most would favor the use of the right hand to advance the ETT through the right nostril while using the left hand to feel the anterior neck to assess the position of the tip of the ETT during blind nasal intubation. In the absence of a septal abnormality (e.g., a septal deviation) , traditional teaching also suggests using the right nos­ tril over the left for nasal intubation.71 It is generally felt that the left-facing bevel of the tracheal tube is the main cause of nasal trauma. The nasal mucosa over the turbinates is highly vascular and can be easily traumatized. It is likely that the mucosa over

the left turbinate is particularly at risk during left-sided intu­ bation since the bevel tends to impact directly against it. So, to minimize trauma, most practitioners would insert the ETT with the bevel facing the flat nasal septum rather than facing the irregularly shaped turbinates along the lateral wall of the nasal cavity. However, others consider that the tip of the tracheal tube is more likely to cause nasal trauma than the bevel and therefore it is more reasonable to have the tip of the ETT to advance alongside the septal mucosa during intubation. Hence, some practitioners choose to advance the ETT through the left nostril during nasal intubation. Unfortunately, no scientific evidence currently exists to suggest that one nostril is safer than the other for nasal intubation in patients with a normal nasal anatomy.72 Instead of debating which is the preferred nostril to minimize the risk of injury, it is perhaps more important to properly prepare the ETT (e.g., selecting an appropriate size ETT and softening the ETT in warm saline or water) and the patient (e.g. , apply vasoconstrictor to the nostrils prior to performing the nasal intu­ bation) , resist excessive force during intubation, and change to a different nostril or use a smaller ETT when it becomes necessary. • How Do You Perform a Blind Nasal Tracheal

I ntubation?

The answer to this question is largely determined by the indica­ tion for tracheal intubation. In elective situations, the nares are best prepared with a vasoconstrictor (although there is little evi­ dence that this maneuver reduces bleeding or enhances success rates) and the upper airway topicalized with local anesthetic. Light sedation using drugs such as short-acting opioids, ketamine, or benzodiazepines may be required to improve patient cooperation and for anxiolysis. However, in emergency situations with life­ threatening hypoxemia, this may not be possible. The potential for severe epistaxis with airway hemorrhage must always be borne in mind. Rescue airway equipment including EGOs and surgical airway kits should be available. Vital sign monitors are attached and the patient is fully denitrogenated if practical prior to the procedure being undertaken. Cervical spine precautions and cricoid pressure should be instituted as indicated. Maintenance of spontaneous ventilation is preferred to assist with successful tracheal intubation. Confirmation of tracheal tube placement is obtained by the usual clinical criteria as well as C0 detection 2 methods. Some practitioners insert an appropriately sized naso­ pharyngeal airway, or fully insert their little finger to gently dilate the nostril to minimize bleeding on tube insertion. In addition, this maneuver may help to identifY mid or posterior nares ana­ tomical abnormalities that would preclude use of that nostril. To perform the procedure: (a) Insert the appropriate size ETT into the naris. (b) Gently advance the ETT. Do not use excessive force if there is resistance during insertion. This may mean that the tip of the ETT has entered the depression in the nasopharynx where the Eustachian Tube enters (see Chapter 3) . Consider extending the patient's neck if not contraindicated, or switching to the alternative nostril. Do not use excessive force, which might result in retropharyngeal perforation. (c) Listen for breath sounds as you advance the ETT. The use of whistle devices such as the BAAM Whistle73 (Beck Airway

N o nvi s u a l I ntu bation Tec h n iq ues

TAB L E 1 2- 1 .

Reco m m en d ed M a neuvers for Tro u b l eshooting of B l i n d Nasa l I nt u bation

Position of the ETT I n the pyriform fossa - B u l g e in l atera l neck

In the eso p h a g u s

F I G U R E 1 2- 1 3. The BAAM (Beck Ai rway Ai rfl ow M o n itor) W h i stle.

Anterior t o e p i g l otti s - S u p ra l a ryngea l b u l g e at l evel of hyo i d bone I m p i n g i n g the a ryte n o i d ca rti l a g e a n d voca l cord

Recom mended Maneuvers Withd raw ETI i nto hypo p h a rynx ti l l b reath sou n d s a re hea rd, red i rect a n d rotate ETT away fro m the b u l g e. Tu rn pati ent's head to i psi l ate ra l side if n o contra i n d icat i o n s Withd raw ETI i nto hypo p h a rynx, adva nce ETI after i nfl ati ng cuff with 20 ml of a i r. ETI wi l l be d i s p l a ced a nte riorly towa rd g l ottic ope n i n g . Once ETI t i p is i ntra l a ryngeal, d efl ate cuff befo re adva n c i n g ETI i nto tra c h e a . S l i g ht exte n s i o n o f the neck if not contra i n d i cated U se an E n d otrol™ ETT S l i g ht fl exion of t h e neck fa c i l itates passage

With d raw ETI and rotate tu be gently to rea l i g n bevel with voca l cord s

F I G U R E 1 2- 1 4. The Pat i l A u d i b l e I nt u bation G u ide.

Airflow Monitor, Great Plains Ballistics, Inc. , Lubbock, TX) (Figure 12- 1 3) or the Patil Audible Intubation Guide (Mercury Medical, Clearwater, FL) (Figure 12- 14) to pro­ vide an auditory cue in the form of a to and fro whistle to facilitate nasotracheal intubation may be useful. Other adjuncts such as the light-guided devices, capnography, and endotracheal tube stethoscopes have also been described?4-77 Careful inspection and palpation of the neck can also pro­ vide useful clues to the location of the tip of the ETT. (d) Neck flexion is a commonly used maneuver to aid in passage of the ETT into the trachea if the ETT repeatedly impinges anterior to the epiglottis. In the event that esophageal entry occurs repeatedly, neck extension is employed. Clearly, this maneuver should not be performed in patients with known or suspected cervical pathology. Alternatively, the ETT can be withdrawn to the hypopharynx and the cuff of the ETT inflated with 20 mL of air to produce anterior displacement of the ETT tip toward the glottic opening.46 An Endotrol® ETT (Mallinckrodt Medical Inc., Argyle, NY) may increase the success of the technique.78-81 Table 12- 1 summarizes the recommended maneuvers for tube manipulation. (e) Advance the ETT past the vocal cords during inspiration. Confirm ETT placement once tracheal entry is suspected.

• Is B l i n d Nasal I ntubation Still Relevant?

The popularity of blind nasal intubation has declined greatly since the advent of paralyzing agents and visual intubating devices. However, blind nasal intubation may be useful in clini­ cal situations where fogging, blood, secretions, and vomitus in the upper airway has rendered visual techniques impossible, or when oral intubation is difficult due to a limited mouth open­ ing and advanced intubating devices are not readily available. Average success rates of blind nasal intubation vary between 57% and 7 1 % with conventional tracheal tubes, and 72% to 86% using directional tip control tubes.81-84 In under-resourced countries, where expensive video and fiberoptic equipment is lacking, blind nasal intubation may be life saving in emergency airway management. Operator competence is the most important determinant of success of blind nasal intubation. Teaching of this technique does not require special equipment. A simple manikin model (Figure 1 2- 1 5) can be used to teach blind nasal intubation in a safe and effective manner without jeopardizing patient safety. 85·86 This allows novice practitioners to practice the tech­ nique in a controlled environment before bringing blind nasal intubations into real clinical situations.

233

234

Ai rway Tec h n i q ues

TAB L E 1 2-2.

Eq u i pment N ecessa ry to Fac i l itate Lig ht­ G u ided Retrog rad e I ntu batio n

F I G U R E 1 2- 1 5. Tea c h i n g blind n a s a l i ntu bation using a BAAM W h i st l e in a m a n i ki n in Rwa n d a .

RETROGRADE I NTU BATION • What Is Retrograde Intubation and When

Was It I ntrod uced?

In 1 960, two surgeons, Butler and Cirillo,87 reported the first retrograde intubation in surgical patients through an exist­ ing tracheostomy opening. The technique was subsequently modified by Waters88 who performed a cricothyroid membrane puncture using a Touhy needle. Waters inserted an epidural catheter through the Touhy needle and advanced it cephalad so that the catheter was brought out through the mouth. An ETT was then advanced over the epidural catheter into the trachea while pulling both ends of the catheter taut. After the ETT entered the trachea, the catheter was pulled out through the oral cavity. • How Do You Perform a Retrograde

I ntubation?

To improve success rates for this technique many modifica­ tions have been suggested since its introduction. For instance, the use of a guide wire rather than an epidural catheter, even though the authors continue to prefer an epidural catheter because it is substantially cheaper, more pliable, and perhaps less traumatic. ( 1 ) Equipment: Although a preassembled kit is commercially available, the list of equipment necessary for the retrograde intuba­ tion is summarized in Table 12-2. (2) Patient preparation: In contrast to the sniffing position advocated for laryn­ goscopic intubation, the patient's head and neck should be in a neutral or relatively extended position to favor an epi­ glottic position that is off the posterior pharyngeal wall. The epiglottis is almost in contact with the posterior pharyngeal wall when the head is in the sniffing position, making it dif­ ficult for the ETT to go underneath the epiglottis. In obese patients or patients with an extremely short neck, placing a pillow under the shoulders and neck may be useful.

Eq u i pment

Function

C h l orhexi d i n e o r ot h e r a ntiseptic so l ut i o n s An a p pro p ri ate ly sized tra c h e a l tu be An 1 8- g a u g e i ntrave n o u s a n g iocath A 5 ml fl u i d -fi l led syri n g e 2 1 -g a u g e e p i d u ra l catheter (Po rtex) o r a 1 1 0 e m l o n g g u i d e-wi re (0.03 8 i n c h d i a m eter) A ta pered a nte rog ra d e g u i d e catheter i s req u i red for the g u i dewi re tech n i q u e 70 em M ag i l l fo rce ps and a l a ry n g oscope

To m i n i m ize r i s k of i nfecti o n

Two H e m ostats 4 x 4 g a uze Wate r-sol u b l e l u bricant

F o r tra c h e a l i ntu bati o n Cri cothyro i d m e m b ra n e p u n ct u re As p i ration of free a i r To g u i d e t h e ETT i nto the tra c h ea

To fa c i l itate the ETT i nto the tra c h ea

To retrieve the e p i d u ra l catheter fro m t h e o ra l cavity To h o l d the e p i d u ra l catheter o r g u i d e-wi re To h o l d t h e to n g u e fo rwa rd d u ri n g i ntu bati o n To l u b ri cate the ti p o f t h e ETT

(3) The "Classic" Technique: This technique can be used in patients who are awake under topical anesthesia with sedation or under general anesthesia.63•89 Although a cricothyroid membrane punc­ ture can be performed using a blunt tip Touhy needle, the angiocath is less traumatic and substantially easier to use. The cricothyroid membrane is punctured at an angle 90 degrees to the skin using the 1 8-gauge angiocath (or needle) in the midline position. Correct tracheal placement can be confirmed by aspirating a free stream of air bubbles in a fluid-filled syringe. Once the tracheal lumen is entered, the angiocath needle is removed, leaving the catheter behind. The angiocath catheter is then angled at 45 degrees in a cephalad direction through which a 2 1 -gauge epidural catheter (or a guide wire) can be inserted and advanced cephalad into the oropharynx. The epidural catheter can be readily retrieved from the mouth using the Magill forceps. After the removal of the angiocath catheter from the ante­ rior neck, and to avoid accidentally pulling the epidural catheter (or the guide wire) through, a hemostat is attached to the distal end of the epidural catheter or guide wire at the skin entry point. Similarly, a hemostat is attached to the epidural catheter or wire where it emerges from the mouth. The epidural catheter or guide wire is then inserted into the ETT. Lubrication of the tip of the ETT will facilitate its entry into the glottic opening. To elevate the tongue and epiglottis away from the posterior pharyngeal wall, the

N o nvi s u a l I ntu bation Tec h n iq ues

tongue of the patient is then gently pulled forward by an assistant if the procedure is performed under general anes­ thesia. While pulling the epidural catheter or the guide wire taut from both ends by an assistant, the ETT is inserted into the oropharynx in the midline position. When the tip of the ETT enters the glottic opening, the tension of the epidural catheter at the distal end should be relaxed and the ETT can be advanced gently into the trachea. (For the guide wire technique, the guide wire should be removed before advancing the ETT into the trachea.) While leaving the epidural catheter in place, correct placement of ETT is confirmed using end tidal C0 . The epidural catheter is 2 then removed through the mouth end of the ETT. • What Other Tech niq ues Ca n be Used to

Improve the Success Rate of the Retrograde I ntubation?

While retrograde intubation is a simple technique, the suc­ cess rate of tracheal intubation is unacceptably low. In a study involving 35 cadavers, Lenfant et al.90 reported a success rate of 69% using the conventional guide wire technique. The investigators suggested that failures were likely due to incor­ rect positioning of the endotracheal tube. In addition, because of the short distance between the cricothyroid membrane and the vocal cords, the depth of insertion of the ETT is not deep ( < 1 0 mm in adults89) , and accidental extubation can easily occur during the removal of the guide wire with this technique. A number of technique modifications have been suggested to improve the success rate of the retrograde intubation. These include the insertion of the epidural catheter (or guide wire) through the "Murphy's" eye of the endotracheal tube91 from "outside" to "inside" to increase the length of ETT actually in the trachea, the use of a subcricoid puncture92 for the same reason, pulling rather than guided technique,93 and employing a multi-lumen catheter guide.94 To increase the stiffness and allow easier negotiation of the ETT through the oropharynx into the trachea, a tapered tip anterograde guide catheter (e.g., pediatric tube changer) placed over the guide wire has been sug­ gested to improve the effectiveness of retrograde intubation.89·95 Although these modifications are useful, they do not overcome the difficulty of determining the location of the tip of the ETT during intubation. Simultaneous visualization of the ETT pas­ sage can be achieved if a flexible endoscope is placed through the nose beforehand. Retrograde intubation using a guide wire passed retrograde through the working channel of a flexible bronchoscope has also been shown to be effective as the tip of the ETT can be guided into the glottis under indirect vision.96'98 However, the broncho­ scope is expensive and the retrograde passage of the guide wire through the working channel of the bronchoscope can poten­ tially damage the internal lining of the channel.99 In addition, visualization of the laryngeal structures through a bronchoscope can also be difficult in the presence of blood and secretions. The tip of the ETT can also be guided into the trachea using transillumination. The placement of the bulb of a lightwand at the tip of the ETT during retrograde intubation may assist ETT advancement. A bright circumscribed glow can be readily

seen in the anterior neck when the tip of the ETT enters the glottic opening and advances to the cricothyroid membrane puncture site potentially improving the success rate of the tech­ nique. The light-guided retrograde intubating technique using the flexible TL (without the stiff internal stylet) has been shown to be an effective and safe in patients with cervical spine instability. 63

WHAT IS TH E CLI N I CAL UTI LITY OF TH E RETROG RADE I NTU BATION? While retrograde intubation is not often considered to be a technique of choice, it remains a useful and effective tech­ nique. The technique can be performed either under general anesthesia or awake with skin infiltration and topical anes­ thesia.63·89 In the originaP00 and revised American Society of Anesthesiologists Difficult Airway Algorithms, 101'10 2 retrograde intubation is recommended as an alternative method of intu­ bation when encountering a difficult tracheal intubation if the patient's lungs can still be ventilated. In other words, retrograde intubation can play an important role in the management of a "cannot intubate, but can oxygenate" failed airway. It can also be used in patients with a predicted difficult laryngoscopic intubation but no anticipated difficulties in BMV, such as patients with cervical spine instability.63 • What Are the Compl ications of the

Retrograde I ntubation?

While the retrograde intubation is an effective intubating tech­ nique, it has some potential complications. Although rare, com­ plications, such as sore throat, hoarseness, bleeding (puncture site, and peritracheal hematomas) , subcutaneous emphysema, upper airway obstruction (secondary to subcutaneous emphy­ sema) , pneumothorax, pneumomediastinum, pretracheal abscess, and trigeminal nerve trauma have been reported with retrograde intubation.89 Fortunately, most of these complica­ tions are minor and self-limiting. It should be emphasized that, compared to the Touhy needle, the use of an 1 8-gauge angio­ cath or needle has made the cricothyroid membrane puncture substantially easier to perform and less traumatic compared to the Touhy needle. In addition, to avoid wound contamination by the oral bacterial flora, the epidural catheter or guidewire should be removed from the cephalad end wherever possible following intubation.

S U M MARY Although tracheal intubation under direct vision using a laryn­ goscope remains the conventional method of tracheal intuba­ tion, it is challenging in a small percentage of patients. Many alternative techniques have been developed over the last several decades to improve the success rate. However, these techniques often require expensive equipment, specialized skills, and are sometimes not particularly useful for patients in an emergency situation with limited resources. Nonvisual intubating techniques occupy an important role in airway management. Over the last several decades, these

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Ai rway Tec h n i q ues

nonvisual techniques have been shown to be effective and safe in securing an airway. However, as with all technical skills, one has to recognize that there is a learning curve and a skills main­ tenance requirement for all of these techniques to be of clinical utility.

REFERENCES I . Bair AE, Filbin MR, Kulkarni RG, Walls RM . The failed intubation attempt in the emergency department: analysis of prevalence, rescue tech­ niques, and personnel. J Emerg Med. 2002;23: 1 3 1 - 1 40. 2. Konrad C, Schupfer G, Wiedisbach M, Gerber H . Learning manual skills in anesthesiology: is there a recommended number of cases for anesthetic procedures? Anesth Analg. 1 998;86:635-639. 3 . Mulcaster JT, Mills J, Hung OR, et al. Laryngoscopic intubation: learning and performance. Anesthesiology. 2003 ;98:23-27. 4. Macintosh RR. An aid to oral intubation (Letter) . BMJ. 1 949; 1 :28. 5 . Venn PH. The gum elastic bougie. Anaesthesia. 1 993;48:274-275. 6. El-Orbany MI, Salem MR, Joseph NJ. The Eschmann tracheal tube intro­ ducer is not gum, elastic, or a bougie. Anesthesiology. 2004; I 0 1 : 1 240. 7. Cormack RS , Lehane J. Difficult tracheal intubation in obstetrics. Anaesthesia. 1 984;39: I I 0 5 - 1 1 1 1 . 8. Hagberg CA. Special devices and techniques. Anesthesia! Clin North Am. 2002;20:907 -932. 9. Marciniak D, Smith CE. Emergent retrograde tracheal intubation with a gum-elastic bougie in a trauma patient. Anesth Ana/g. 2007; I 05 : 1 720- 1 72 1 . 1 0 . Braude D , Webb H , Stafford J , et al. The bougie-aided cricothyroromy. Air Medj. 2009;28 : 1 9 1 - 1 94. 1 1 . Reardon R, Joing S, Hill C. Bougie-guided cricothyrotomy technique. Acad Emerg Med. 20 1 0 ; 1 7:225. 12. Moscati R, Jehle D, Christiansen G, et a!. Endotracheal tube introducer for failed intubations: a variant of the gum elastic bougie. Ann Emerg Med. 2000;36:52-56. 13. Hodzovic I, Latto IP, Wilkes AR, Hall JE, Mapleson WW. Evaluation of Frova, single-use intubation introducer, in a manikin. Comparison with Eschmann multiple-use introducer and Portex single-use introducer. Anaesthesia. 2004;59 : 8 1 1 - 8 1 6 . 1 4 . Levitan R , Ochroch EA. Airway management and direct laryngoscopy: a review and update. Crit Care Clin. 2000; 1 6:373-388. 1 5 . Weiss M. Management of difficult tracheal intubation with a video-optically modified Schroeder intubation stylet. Anesth Analg. 1 997; 8 5 : 1 1 8 1 - 1 1 82. 1 6. Dutta A, Kumra VP, Sood J, Swaroop A. Guided tactile probing: a modi­ fied blind orotracheal intubation technique for the problem-oriented dif­ ficult airway. Acta Anaesthesia! Scand. 2005;49: I 06- 1 0 9 . 1 7 . Bokhari A , Benham SW, Popat MT. Management of unanticipated dif­ ficult intubation: a survey of current practice in the Oxford region. Eur J Anaesthesia!. 2004;2 1 : 1 23 - 1 27. 1 8 . Combes X, Le Roux B, Suen P, et al. Unanticipated difficult airway in anesthetized patients: prospective validation of a management algorithm. Anesthesiology. 2004; I 00: 1 1 46- 1 1 50. 1 9. Nolan JP, Wilson ME. Evaluation of the gum elastic bougie. Anaesthesia. 1 992;47:878-88 1 . 20. Nolan J P, Wilson ME. Orotracheal intubation patients with potential cer­ vical spine inj ury. Anaesthesia. 1 993;48:630-633. 2 1 . Annamaneni R, Hodzovic I, Wilkes AR, Latto IP. A comparison of simu­ lated difficult intubation with multiple-use and single-use bougies in a manikin. Anaesthesia. 2003;58 :45-49. 22. Jones I, Roberts K. Towards evidence based emergency medicine: best BETs from the Manchester Royal Infirmary. Difficult intubation, the bou­ gie and the stylet. Emerg Med j. 2002; 1 9 :433-434. 23. Nocera A. A flexible solution for emergency intubation difficulties. Ann Emerg Med. 1 9 96;27:665-667. 24. Phelan MP. Use of the endotracheal bougie introducer for difficult intuba­ tions. Am J Emerg Med. 2004;22:479-482. 25. Morton T, Brady S, Clancy M. Difficult airway management in English emergency departments. Anaesthesia. 2000 ; 5 5 :485-488. 26. Henderson JJ, Popat MT, Latto IP, Pearce AC. Difficult Airway Society guidelines for management of the unanticipated difficult intubation. Anaesthesia. 2004;59:675-694. 27. Kidd JF, Dyson A, Latto IP. Successful difficult intubation. Use of the gum elastic bougie. Anaesthesia. 1 98 8;43:437-438. 28. Arndt GA, Cambray AJ, Tomasson J. Intubation bougie dissection of tracheal mucosa and intratracheal airway obstruction. Anesth Ana/g. 2008; I 07:603-604.

29. Kadry M, Popat M. Pharyngeal wall perforation-an unusual com­ plication of blind intubation with a gum elastic bougie. Anaesthesia. 1 999;54:393-408. 30. Smith BL. Haemopneumothorax following bougie-assisted tracheal intu­ bation. Anaesthesia. 1 994;48:9 1 . 3 1 . Gardner M , Janokwski S . Detachment o f the tip o f a gum-elastic bougie. Anaesthesia. 2002;57:88-89. 32. Tuzzo DM, Frova G. Application of the self-inflating bulb to a hollow intubating introducer. Minerva Anestesiol. 200 I ;67: 1 27- 1 32. 33. Yamamura H, Yamamoto T, Kamiyama M. Device for blind nasal intuba­ tion. Anesthesiology. 1 959;20:22 1 . 34. Ainsworth QP, Howells TH. Transilluminated tracheal intubation. Br J Anaesth. 1 989;62:494-497. 35. Ellis DG, Stewart RD, Kaplan RM , Jakymec A, Freeman JA, Bleyaert A. Success rates of blind orotracheal intubation using a transillumination technique with a lighted stylet. Ann Emerg Med. 1 986; 1 5 : 1 38 - 1 42. 36. Vollmer TP, Stewart RD, Paris PM, Ellis D, Berkebile PE. Use of a lighted stylet for guided orotracheal intubation in the prehospital setting. Ann Emerg Med. 1 98 5 ; 1 4 : 324-328. 37. Hung OR, Milne A, d'Entremont M. Tracheal intubation device. Canadian Patent Office. April 1 7, 20 14. 38. Milne AD, d'Entremont MI, Hung OR. Optimum brightness of a new light-emitting diode lightwand device in a cadaveric model-a pilot study. Can ] Anaesth. 20 1 6;63:770-77 1 . 39. Nishiyama T, Matsukawa T, Hanaoka K. Safety of a new lightwand device (Trachlight) : temperature and histopathological study. Anesth Ana/g. 1 998;87:7 1 7-7 1 8 . 40. Hosokawa K, Nakaj ima Y, Hashimoto S. Chipped rail gear of a lightwand device: a potential complication of tracheal intubation. Anesthesiology. 2008; 1 09 : 3 5 5 . 4 1 . Chen T H , Tsai S K , Lin CJ, e t a l . Does the suggested lightwand bent length fit every patient? The relation between bent length and patient's thyroid prominence-to-mandibular angle distance. Anesthesiology. 2003 ;98: 1 070- 1 076. 42. Hung OR, Pytka S, Morris I, et al. Clinical trial of a new lightwand (TrachlighfM) to intubate the trachea. Anesthesiology. 1 995;83: 509-5 1 4. 43. Stewart RD, LaRosee A, Kaplan RM , llkhanipour K. Correct position­ ing of an endotracheal tube using a flexible lighted stylet. Crit Care Med. 1 990; 1 8 :97-99. 44. Hung OR, Tibbet JS, Cheng R, Law JA. Proper preparation of the Trachlight and endotracheal tube to facilitate intubation. Can J Anaesth. 2006; 5 3 : I 07 - I 08. 4 5 . Chung YT, Sun MS, Wu HS. Blind nasotracheal intubation is facilitated by neutral head position and endotracheal tube cuff inflation in spontane­ ously breathing patients. Can J Anaesth. 2003;50: 5 1 1 -5 1 3 . 4 6 . Gorback MS. Inflation of the endotracheal tube cuff a s a n aid t o blind nasal endotracheal intubation [letter] . Anesth Ana/g. 1 987;66: 9 1 3 . 47. Asai T, Latta I P. Unexpected difficulry i n the lighted stylet-aided tracheal intubation via the laryngeal mask. Br JAnaesth. 1 996;76: 1 1 1 - 1 1 2 . 48. Agro F, Brimacombe J, Marchionni L , Carassiti M, Cataldo R . Nasal intu­ bation with the Trachlight. Can J Anaesth. 1 999;46:907 -908. 49. Aoyama K, Takenaka I, Nagaoka E, et al. Potential damage to the lar­ ynx associated with light-guided intubation: a case and series of fiberoptic examinations. Anesthesiology. 200 I ;94: 1 65- 1 67. 50. Stone DJ, Stirt JA, Kaplan MJ, McLean WC. A complication of light­ wand-guided nasotracheal intubation. Anesthesiology. 1 984; 6 1 :780-78 1 . 5 1 . Debo RF, Colonna D , Dewerd G , Gonzalez C . Cricoarytenoid sublux­ ation: complication of blind intubation with a lighted stylet. Ear Nose Throat j. 1 989;68 : 5 1 7-520. 52. Tsutsui T, Setoyama K. A clinical evaluation of blind orotracheal intuba­ tion using Trachlight in 5 1 1 patients. Masui. 200 1 ; 50: 854-8 5 8 . 5 3 . Hung OR, Pyrka S, Morris I, Murphy M, Stewart RD. Lightwand intuba­ tion: II. Clinical trial of a new lightwand to intubate patients with difficult airways. Can J Anaesth. 1 99 5 ;42:826-830. 54. Favaro R, Tordiglione P, Di Lascio F, et al. Effective nasotracheal intu­ bation using a modified transillumination technique. Can J Anaesth. 2002;49:9 1 -9 5 . 5 5 . Inoue Y, Koga K , Shigematsu A . A comparison of two tracheal intubation techniques with Trachlight and Fastrach in patients with cervical spine disorders. Anesth Ana/g. 2002;94:667 -67 1 . 5 6 . Iseki K, Watanabe K , Iwama H . Use o f the Trachlight for intubation i n the Pierre-Robin syndrome. Anaesthesia. 1 997;52: 8 0 1 -802. 57. Gille A, Komar K, Schmidt E, Alexander T. Transillumination technique in difficult intubations in heart surgery. Anasthesiol fntensivmed Notfollmed Schmerzther. 2002;37:604-608 . 5 8 . Agro F, Benumof JL, Carassiti M, Cataldo R , Gherardi S , Barzoi G. Efficacy of a combined technique using the Trachlight together with direct

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61. 62. 63. 64. 65. 66. 67. 68. 69.

70.

71. 72. 73.

74.

75. 76. 77. 78. 79. 80.

81.

82.

83.

84.

85. 86. 87. 88. 89. 90.

laryngoscopy under simulated difficult airway conditions in 350 anesthe­ tized patients. Can J Anaesth. 2002;49: 525-526. Asai T, Latto IP. Use of the lighted stylet for tracheal intubation via the laryngeal mask airway. Br] Anaesth. 1 995;75: 503-504. Fan KH, Hung OR, Agro F. A comparative study of tracheal intubation using an intubating laryngeal mask (Fastrach) alone, or together with a lightwand (Trachlight) . J Clin Anesth. 2000; 1 2: 5 8 1 -5 8 5 . Gutstein HB. Use of the Bullard laryngoscope and lighrwand in pediatric patients. Anesthesiol Clin North Am. 1 998; 1 6:795-8 1 2 . McGuire G, Krestow M . Bullard assisted Trachlight technique. Can J Anaesth. 1 999;46:907. Hung OR, AI-Qatari M . Light-guided retrograde intubation. Can J Anaesth. 1 997;44: 877-8 82. Addas BM, Howes WJ, Hung OR. Light-guided tracheal puncture for percutaneous tracheostomy. Can ] Anaesth. 2000;47: 9 1 9-922. Stewart RD. Tactile orotracheal intubation. Ann Emerg Med. 1 984; 1 3 : 1 75 . Stewart RD. Digital intubation. I n : Dailey RH, Simon B, Stewart RD, et a!. , eds. 7he Airway: Emergency Management. St. Louis, MO: Mosby; 1 992. Hancock PJ, Peterson G. Finger intubation of the trachea in newborns. Pediatrics. 1 992;89:325-327. Korber TE, Henneman PL. Digital nasotracheal intubation. J Emerg Med. 1 989;7:275 . Murphy MF, Hung 0. Blind digital intubation. In: Benumof JL, ed. Airway Management: Principles and Practice. 1 st ed. Philadelphia, PA: Mosby-Year Book Inc; 1 996:277-28 1 . Law JA, Broemling N , Cooper RM , et a!. The difficult airway with recommendations for management-part !-difficult tracheal intuba­ tion encountered in an unconscious/induced patient. Can J Anaesth. 2 0 1 3;60: 1 0 8 9- 1 1 1 8 . Aitkenhead AR, Smith G. Textbook of Anaesthesia. Edinburg: Churchill Livingstone; 1 998. Smith JE, Reid AP. IdentifYing the more patent nostril before nasotracheal intubation. Anaesthesia. 200 1 ;56:25 8-262. Cook RT Jr. , Stene JK, Marcolina B Jr. Use of a beck airway airflow moni­ tor and controllable-tip endotracheal tube in two cases of nonlaryngo­ scopic oral intubation. Am ] Emerg Med. 1 99 5 ; 1 3 : 1 80-1 83. Dong Y, Li G, Wu W, Su R, Shao Y. Lightwand-guided nasotracheal intu­ bation in oromaxillofacial surgery patients with anticipated difficult air­ ways: a comparison with blind nasal intubation. fntJ Oral Maxillofoc Surg. 20 1 3 ;42: 1 049- 1 05 3 . Harris RD, Gillett MJ, Joseph A P, Vinen JD. A n aid t o blind nasal intuba­ tion. ] Emerg Med. 1 998; 1 6:93-95. King HK, Wooten JD. Blind nasal intubation by monitoring end-tidal C02. Anesth Ana/g. 1 989;69:4 1 2-4 1 3 . Nofal 0. Awake light-aided blind nasal intubation: prototype device. B rJ Anaesth. 20 1 0; 1 04:254-259. Asai T. Use of the endotrol endotracheal tube and a light wand for blind nasotracheal intubation. Anesthesiology. 1 999;9 1 : 1 5 57. Asai T. Endotrol tube for blind nasotracheal intubation (Letter) . Anaesthesia. 1 996;50: 507. Cook RT Jr. , Stene JK Jr. The BAAM and endotrol endotracheal tube for blind oral intubation. Beck Airway Air Flow Monitor. J Clin Anesth. 1 993;5 :43 1 -432. Hooker EA, Hagan S , Coleman R, Heine MF, Greenwood P. Directional­ tip endotracheal tubes for blind nasotracheal intubation. Acad Emerg Med. 1 996;3:586-589. Dronen SC, Merigian KS, Hedges JR, Hoekstra JW, Borron SW A com­ parison of blind nasotracheal and succinylcholine-assisted intubation in the poisoned patient. Ann Emerg Med. 1 987; 1 6: 650-652. O'Brien OJ, Danzl OF, Hooker EA, Daniel LM, Dolan MC. Prehospital blind nasotracheal intubation by paramedics. Ann Emerg Med. 1 989; 1 8 : 6 1 2-6 1 7. O'Connor R E, Megargel RE, Schnyder ME, Madden JF, Bitner M, Ross R. Paramedic success rate for blind nasotracheal intubation is improved with the use of an endotracheal tube with directional tip control. Ann Emerg Med. 2000;36:328-332. Iserson KV Blind nasotracheal intubation: a model for instruction. Ann Emerg Med. 1 984; 1 3 :60 1 -602. Zhang J, Lamb A, Hung 0, Hung C, Hung D . Blind nasal intubation: teaching a dying art. Can ] Anaesth. 20 1 4;6 1 : 1 05 5 - 1 056. Butler FS, Circillo AA. Retrograde tracheal intubation. Anesth Ana/g. 1 960;39:333-338. Waters OJ. Guided blind endotracheal intubation. Anaesthesia. 1 963; 1 8 : 1 5 9 . Ohara SS. Retrograde tracheal intubation. Anaesthesia. 2009;64: I 094- 1 1 04. Lenfant F, Benkhadra M, Trouilloud P, Freysz M. Comparison of two techniques for retrograde tracheal intubation in human fresh cadavers. Anesthesiology. 2006; 1 04:48-5 1 .

9 1 . Bourke D. Modification of retrograde guide for endotracheal intubation. Anesth Analg. 1 974;53 : 1 0 1 3- 1 0 1 4 . 92. Shantha TR. Retrograde intubation using the subcricoid region. Br J Anaesth. 1 992;68: I 09-1 1 2 . 93. Abdou-Madi M N , Trop D . Pulling versus guiding: a modification of ret­ rograde guided intubation. Can ] Anaesth. 1 989;36:336-339. 94. Ohara SS. Retrograde intubation-a facilitated approach. Br J Anaesth. 1 992;69:63 1 -633. 9 5 . Tobias R. Increased success with retrograde guide for endotracheal intu­ bation. Anesth Ana/g. 1 983;62:366-367. 96. Carlson CA, Perkins HM. Solving a difficult intubation. Anesthesiology. 1 986;64:537. 97. Przybylo HJ, Stevenson GW, Vicari FA, Horn B, Hall SC. Retrograde fibreoptic intubation in a child with Nager's syndrome. Can J Anaesth. 1 9 96;43 :697-699. 98. Rosenblatt WH, Angood PB, Maranets I, Kaklamanos IG, Garwood S . Retrograde fiberoptic intubation. Anesth Ana/g. 1 997;84: 1 1 42- 1 1 44. 99. Ovassapian A, Mesnick PS. The art of fiberoptic intubation. Anesthesiol Clin North Am. 1 99 5 ; 1 3:39 1 -409. 1 00. American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Practice guidelines for the difficult airway. Anesthesiology. 1 993;78 : 5 97-602. I 0 I. American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Practice guidelines for management of the difficult airway: an updated report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology. 2003;98: 1 269-1 277. 1 02. Apfelbaum JL, Hagberg CA, Caplan RA, et a!. Practice guidelines for management of the difficult airway: an updated report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology. 20 1 3; 1 1 8 :25 1 -270.

SELF - EVALUATION QU ESTIONS 1 2. 1 . Which o f the following conditions does not affect the effectiveness oflight-guided intubation using a lightwand? A. morbid obesity B . foreign body in the upper airway C. retropharyngeal abscess D. blood and secretion in the oropharynx E. large goiter in the anterior neck 12.2. Which of the following modifications has not been shown to improve the success rate of the retrograde intubation? A. The use of a subcricoid puncture. B. The use a guide wire passing through the working channel of a flexible bronchoscope. C. The use of a flexible lightwand. D. The use of a guide-wire instead of an epidural catheter. E. The insertion of the guide wire through the "Murphy's" eye of the endotracheal tube during intubation. 1 2 . 3 . Which of the following is NOT a characteristic feature of the Eschmann Tracheal Tube Introducer ("gum-elastic bougie")? A. The Eschmann Introducer is 60 em long. B. The Eschmann Introducer has a J (coude) tip (a 3 5-degree angle bend) at the distal end. C. The Eschmann Introducer has a hollow lumen with two side ports. D . The Eschmann Introducer is a reusable device. E. The Eschmann Introducer consists of a core of tube woven from polyester threads covered with a resin layer.

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C H A PT E R 1 3

Extraglottic Devices for Ventilation an d Oxygenation Liem Ho, Thomas J. Coonan, and Orlando R. Hung

CAS E PRESENTATION . . . . . . . . . . . . . . . . . . . . . . . . . . . 238 I NTRO DUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LARYNGEAL MASK AI RWAY CLASSIC LMA ® .

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FASTRACH'M I NTU BAT I N G LARYNGEAL MASK AI RWAY (I LMA) . . . . . . . . . . . . . . . . . . . . . . . . . 243 .

LARYNGEAL MASK AI RWAY P ROSEAL ® (P LMA) .

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244 246

T H E COM BITU BE® (CBT) . . . . . . . . . . . . . . . . . . . . . . . . .

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LARYNGEAL TU BE® (KI NG LT AI RWAY® [ LT]) . . . . . . . . . . . . . . . . . . . . . . . . . . . .

248

LARYVENT® ( LV) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

249

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AI RWAY MANAG E M E NT DEVICE® (AM D) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250 P E R I LARYNGEAL AI RWAY (Cobra P LA® [CPLA]) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250 THE STREAM L I N E D PHARYNX AI RWAY L I N E R (SLI PA®) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 1 T H E Ambu® AuraOnce•M D I S POSABLE LARYNGEAL MASK. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252 iGEL® . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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SELF-EVALUATIO N Q U ESTI O N S . . . . . . . . . . . . . . . . . .

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CAS E PRESENTATION A 57-year-old male was admitted for laparoscopic appendec­ tomy for acute appendicitis. He was otherwise healthy, apart from essential hypertension, for which he took hydrochloro­ thiazide. He had fasted for more than 12 hours. On examination, he was lying in a stretcher in a moderate amount of pain. He was hemodynamically stable. His height was 1 83 em and his weight was 80 kg with a body mass index (BMI) 23.9 kg·m- 2 • His airway examination demonstrated a Mallampati score of II, mouth opening of 4 . 5 em, thyromental distance of 6 em, and good jaw protrusion. He had a full set of teeth, was not obese, and was estimated to be easy to ventilate. His cardiac and respiratory examinations were normal. The patient was premedicated with intravenous midazolam 1 mg, fentanyl 200 meg, and this was followed by denitroge­ nation with 1 00% oxygen by facemask. As he didn't have any indicators of a difficult airway, a decision was made to induce anesthesia with propofol 200 mg and rocuronium 50 mg. Bag-mask-ventilation (BMV) was established with an oral air­ way. Initial evaluation with direct laryngoscopy (DL) using a Macintosh laryngoscope showed a Cormack-Lehane (C/L) Grade 3 view. The first attempt with DL and an Eschmann Tracheal Introducer (ETI) resulted in an esophageal intubation. BMV was reestablished and a Glidescope" was prepared. When the Glidescope" was inserted, only the posterior arytenoids could be visualized, and two attempts with a styleted endotra­ cheal tube (ETT) and a Tracheal Introducer were unsuccessful (and were associated with a small amount of bleeding in the oropharynx) . At this point, the decision was made to attempt flexible bronchoscopy. Unfortunately, BMV became more difficult, the patient's oxygen saturation dropped into the low 80's, and it became necessary to insert nasal and oral pharyngeal airways

Ext ra g l ottic Devices fo r Ve nti l ation a n d Oxygenation

and begin a two-hand and two-person BMV technique. A #4 Laryngeal Mask Airway Classic• (LMA Classic•) was rapidly prepared and inserted without complication, at which point it became possible to easily ventilate the patient. Sevoflurane was selected to maintain anesthesia, and to manage escalating tachycardia and hypertension. A pediatric bronchoscope with an ensleeved Aintree Intubation Catheter (AIC, Cook Medical Inc. , Bloomington, IN) was then inserted through the LMA into the trachea. Both the bronchoscope and the LMA were then removed leaving the AIC in the trachea. An ETT was advanced into the trachea over the AI C. Correct tracheal place­ ment was confirmed by auscultation and capnograph recording. The surgery was uneventful and the patient emerged from anesthesia fully awake, warm, with adequate analgesia, and with no residual neuromuscular blockade. The difficult airway cart was brought to the room. Tracheal extubation was uneventful, although he did complain of a sore throat in the post-anesthetic care unit, which gradually improved. He was later informed of the difficulty and provided with a notice to inform any subse­ quent practitioner of his difficult airway.

and oxygenation. These devices have changed the landscape of contemporary airway management. They are a part of the Difficult Airway Management Algorithm recommended by the American Society of Anesthesiologists (ASA) ,6•7 the Canadian Airway Focus Group,8•9 as well as the Difficult Airway Society10 in managing unanticipated difficult intubations in adults. • Do Man ufacturing Sta ndards Exist for EG Os

to Ensure Patient Safety?

The American Society for Testing and Materials Standards (ASTM) Committee F29 on Anesthetic and Respiratory Equipment has proposed the establishment of standards related to EGOs used in human subjects. A task group has proposed the standardization of: terminology, design, production, manu­ facturing, testing, labeling, and promotion. Devices produced according to the proposed ASTM standards will: •

•

•

I NTRODUCTION • What are Extraglottic Devices? Why Do We

•

Need These Devices?

Difficulties in airway management are associated with signifi­ cant morbidity and mortality, 1 and it is crucial that practitioners responsible for airway management continue to refine existing skills, and acquire new knowledge and skills as they become available. Two decades ago, ventilation and oxygenation were achieved primarily via a facemask, or an ETT. While BMV is seemingly simple to perform, it has limi­ tations. 2 ·3 Tracheal intubation has been considered to be the "gold standard" for providing effective ventilation, while at the same time providing protection from the aspiration of gastric contents. However, tracheal intubation is a skill that is not easily mastered4 and requires regular practice. Employing an extraglottic device (EGO) to successfully facilitate gas exchange may be a more easily acquired skill for the nonexpert airway practitioner. In contrast to a mask placed on the face to provide BMV, an EGO establishes a direct conduit for air to flow when placed in the periglottic area. The terminology has been somewhat con­ fusing since some have referred to these devices as "supraglottic airway devices," although many have components that extend infraglottically (e.g., the Combitube•, the Laryngeal Tube• [King LT in North America] , and the Easy Tube) .5 Hence, we agree with Brimacombe that the term "extraglottic devices," or EGOs, is the more appropriate terminology. EGOs vary in size, shape, and material. Most have bal­ loons, or cuffs, that upon inflation can provide a reasonably tight seal in the upper airway. As illustrated in the case presen­ tation, these EGOs (including the LMA Classic•) have been used successfully as rescue airway devices. There is clear evi­ dence of their effectiveness and safety in providing ventilation

•

Facilitate unobstructed access of respiratory gases to the glot­ tic inlet by displacing tissue; Not require a (external) facial seal to maintain airway patency; Terminate in a 1 5/22 millimeter (mm) connector to facilitate positive pressure ventilation (PPV) via an anesthetic breath­ ing system; Be capable of maintaining airway patency when the ( 1 5/22 mm) airway connector is open to ambient atmosphere; Minimize the escape of airway gases to the atmosphere.

• What EGOs are Commercially Avai lable?

Many EGOs have been introduced. 5 The best known are the Laryngeal Mask Airway Classic•, ProSeal• Laryngeal Mask Airway (PLMA) , Laryngeal Mask Airway Fastrach• (LMA FT) , LMA Supreme• (LMA-S) , and Combitube• (CBT) . Other EGOs such as the Laryngeal Tube• (LT) , CobraPLN (CPLA) , Airway Management Device• (AMD) , LaryVent• (LV) , Air-Q• device, Ambu• AuraOnce Laryngeal Mask, Portex• Soft Seal• Laryngeal Mask, Streamlined Liner of the Pharynx Airway (SLIPN) , and iGei• are also gaining acceptance. There are at least 25 different types of EGOs available. 1 1 This chapter will review the commonly used EGOs, which also have sufficient information available in the literature, but it should not be considered an exhaustive review of all available devices. It should be emphasized that some devices (e.g. , the COPA and PAxpress'") are no longer being manufactured, and so they would not be discussed in this chapter.

LARYNG EAL MASK AI RWAY CLASSIC LMA ® • What Is the LMA? When Was It I ntrod uced?

The LMN (Teleflex•, Morrisville, NC [Figure 13- 1 ] ) was designed in 1 9 8 1 by Dr. Archie Brain, as he searched for a device that was easier to use and more effective than the face mask, and less invasive than a ETT. The LMA is designed to cover the periglottic area and provide continuity of airflow between the environment and the lungs. The device has a wide-bore

239

240

Ai rway Tec h n i q ues

F I G U R E 1 3- 1 . The LMA Cla ssic® h a s a wide-bore tu be con nected to an ova l i nfl ata b l e cuff that sea l s a ro u n d the l a rynx a n d the a per­ t u re ba rs.

tube connecting to an oval inflatable cuff that seals around the larynx. It is currently available in eight different sizes for use in patients ranging from neonates to large adults. Typically, a #3 LMA-Classic is used in teenagers and small adult females, while #4, #5, and #6 are used in average and large size adults. The use of LMAs has transformed the practice of anesthesi­ ology and airway management. 1 2' 13 The LMA is specified in the ASks Difficult Airway Management Algorithm.6•7 Moreover, the LMA has a role in emergency airway management dur­ ing cardiopulmonary resuscitation (CPR) , the transport of the critically ill patient, and in the intensive care unit. 14•15 Although the LMA is a potentially useful device in situations in which tracheal intubation and mask ventilation are not possible (e.g., "can't intubate, can't ventilate" [CICV] , or more appropriately "can't intubate, can't oxygenate" [CIC0] ) ,6·7•9 it should never be used as a substitute for a surgical airway (see Chapters 2) . While this device can provide adequate ventilation and oxygenation, it does not protect the airway from aspiration, and it does not easily allow for the removal of pulmonary secretions. Therefore, when employed as a rescue device, the LMA can only be con­ sidered a temporizing measure, until a more definitive and pro­ tective airway is secured. • What Is the Proper Way to Insert the LMA?

While many techniques have been suggested for the inser­ tion of the device, including the midline approach, the lateral approach, and the thumb technique, 16 the authors recommend the following steps: •

•

•

•

To minimize the risk of down-folding the epiglottis, it is rec­ ommended that the cuff be completely deflated. The LMA cuff should be well lubricated with a water-soluble lubricant. Provided that there is no contraindication to moving the cer­ vical spine, the patient's head and neck should be placed in a sniffing position. A head tilt will help to open the mouth. In order to have clear access to the glottic opening and mini­ mize down-folding of the epiglottis, it is recommended that the practitioner perform a jaw lift using the thumb and index finger of the nondominant hand. This lifts the tongue and epiglottis away from the posterior pharyngeal wall to facilitate placement of the LMA. The LMA should be inserted into the mouth with the index finger placed at the mask-tube junc­ tion, pressing the cuff against the hard palate, and advancing

•

•

the LMA into the oropharynx following the natural curve of the posterior pharyngeal wall. The dimensions and design of the device allow the tip of the LMA to wedge into the hypopharynx. A definite resistance should be felt when the tip of the LMA enters the hypopharynx. Occasionally, resis­ tance is encountered during insertion because of backward folding of the cuff (also called 'tip roll') . Sweeping a finger behind the cuff to redirect it inferiorly into the laryngophar­ ynx can usually overcome this problem.17 Following placement, the cuff should be inflated with the minimal volume of air necessary to achieve an adequate seal. However, this "just-seal" volume may not be adequate to seal the hypopharynx from the esophagus. 16 1herefore, most prac­ titioners commonly inflate the cuff with more volume. In gen­ eral, approximately 20 mL is required for #3, 30 mL for #4, and 40 mL for #5 LMA. Seal characteristics may be improved by ensuring that the LMA is secured in the midline of the mouth, and the head and neck placed in a neutral position. The LMA should be fixed in position by taping it to the face, or by attaching it to the anesthesia breathing circuit. 18

• What Is the Proper Way to Remove

the LMA?

In its normal position, the LMA is less stimulating than an ETT and is generally well tolerated by most patients on emergence. Many studies have compared removal under deep anesthesia versus while awake. Although airway obstruction appears to be less frequent if the device is removed with the patient awake, this technique is associated with more coughing, laryngospasm, biting, and hypersalivation. 19 While much controversy remains, it is the opinion of the authors that, in adults, the LMA should be removed awake. This is particularly true if mask ventilation is expected to be difficult. Many pediatric airway practitioners prefer removal under deep anesthesia, as children are more prone to laryngospasm. It is unclear whether the LMA should be removed with the cuff deflated or inflated. Some recommend an inflated cuff because of its capacity to remove secretions that accumulate above the device from the oral cavity. 20 Others argue that the cuff should be deflated to minimize trauma and damage to the cuff itself Brimacombe recommends the removal of the LMA with the cuff partially deflated. 1 9 • W h a t A r e the Adva ntages a n d

Disadva ntages o f Using the L M A as Opposed to a n E n d otracheal Tu be?

Brimacombe conducted a meta-analysis of randomized prospec­ tive trials involving 2440 patients comparing the LMA with other forms of airway management, including tracheal intuba­ tion. 2 1 He reported many advantages of the LMA including: rapidity and ease of placement, particularly for inexperienced operators; improved hemodynamic stability on induction and during emergence; minimal rise in intraocular pressure follow­ ing insertion; reduced anesthetic requirements for airway toler­ ance; lower frequency of coughing during emergence; improved oxygen saturation during emergence; and a lower incidence of sore throat in adults.

Ext ra g l ottic Devices fo r Ve nti l ation a n d Oxygenation

An additional advantage of the LMA is its utility as a rescue device and during resuscitation. 22 Further, studies have shown that the LMA has less impact on mucociliary clearance than an ETT, and may reduce the risk of retention of secretions, atelec­ tasis, and pulmonary infection. 23 The major disadvantage of the LMA is its inability to seal the larynx and protect against aspiration, gastric insufflation, and air leak with PPV 2 1 The mask is designed in such a way that the distal end of the device is intended to become wedged into the upper esophageal sphincter. However, in reality, the distal end may lie anywhere from the nasopharynx to the hypopharynx. The magnitude of potential gastric insufflation probably depends on the airway pressure generated and the position of the LMA. However, very large series have shown that PPV with the LMA is both safe and effective, with no episodes of gastric dilatation in 1 1 ,9 1 0 LMA anesthetics under both spontaneous and PPV 24 According to a meta-analysis involving 547 LMA publica­ tions, the incidence of gastric aspiration associated with the use of laryngeal mask airway is rare (0.02%) , 2 1 and most of these cases had predisposing risk factors for pulmonary aspi­ ration. However, fatal aspiration of gastric content has been reported, 2 5 and so proper assessment for aspiration risk prior to the use of the LMA is imperative. Most airway practitioners hesitate appropriately to use the LMA in patients with a his­ tory of symptomatic hiatal hernia, gastroesophageal reflux, in obstetrical patients, or in patients with a bowel obstruction. Careful placement of the device, and vigilance at emergence of anesthesia, may attenuate the risk of gastric aspiration. • Is It Safe to Use the LMA for Positive

Pressure Ventilation?

Over the last two decades, the use of a face mask to facilitate the administration of anesthesia has largely been replaced by the LMA. While a few studies have reported the successful use of the LMA for PPV in a variety of patient populations and pro­ cedures, 26-2 8 they involved mostly small numbers of patients, with few large prospective randomized trials. 29 Bernardini and Natalini30 compared the risk of pulmonary aspiration, in a study involving 65,7 1 2 patients, with PPV via an ETT (30,082 pro­ cedures) compared to an LMA (35,630 procedures) . Although three pulmonary aspirations occurred in the LMA group com­ pared to seven with the ETT, there were no deaths related to these pulmonary aspirations. The investigators concluded that, while there was a selection bias related to contraindications and exclusions to the use of the LMA in their study group, the use of a laryngeal mask airway was not associated with an increased risk of pulmonary aspiration, compared with an ETT in this selected population. Based on the current evidence, the LMA appears to be effec­ tive and probably safe for PPV in patients with normal airway resistance and compliance and normal tidal volumes. However, gastroesophageal insufflation may occur when the LMA is used in conjunction with, and in the presence of, decreased pulmo­ nary or chest wall compliance.31·3 2 Pressure-controlled ventilation (PCV) , rather than vol­ ume-controlled ventilation (VCV) , may provide effective

mechanical ventilation in patients with high airway pressure, or reduced lung compliance, while at the same time minimiz­ ing the risk of gastric insufflation with the LMA.33 It must be reemphasized that, although rare, cases of serious and even fatal gastric aspiration associated with the use of LMA have been reported. 2 5·34-36 Because of the potential for serious complica­ tions, more evidence with studies involving a large number of patients may be needed to confirm the safety of the use of the LMA for PPV 29 • How a re LMAs Used Appropriately in

Clin ical Practice?

Since its introduction in 1 988, the LMA has been used in more than 200 million patients worldwide, 13 and it has largely replaced the ETT and face mask for patients undergoing simple and uncomplicated surgical procedures. The extensive use of the LMA is a reflection of its overwhelming effectiveness and safety in a variety of age groups and surgical procedures. The LMA has also been shown to be effective and safe for elective caesarean section in non-obese parturients, though its use for this indication is controversial.37 A meta-analysis of currently available data shows that the LMA is safe and effective for pediatric airway management.38 Furthermore, the LMA has been used successfully in the man­ agement of large numbers of difficult pediatric airways associ­ ated with a variety of congenital anomalies. In 20 1 0, Weiss and Engelhard�9 proposed the use of LMA in the management of the unexpected difficult pediatric airway algorithm. The LMA was approved for resuscitation by the European Resuscitation Council in 1 996,40 and the American Heart Association (AHA) in 2000.41 However, the possibility of gas­ tric insufflation, related to high peak airway pressure, continues to be a concern in these patient populations, similar to those managed with BMV Brimacombe summarized the available evidence with respect to the use of the LMA in the management of the difficult and failed airway.42 With the exception of airway pathology that may interfere with the LMA placement or seal, there is a con­ siderable body of evidence to support the use of the LMA in both predicted and unpredicted difficult airways.6-9 The LMA also provides a conduit for tracheal intubation using either a blind technique, a transillumination technique (using the Trachlight® without the stiff wire stylet) ,43 ,44 or a flex­ ible bronchoscope (FB) together with an AIC (Cook Medical Inc. , Bloomington, IN) .45.46 Intubation success rates through the LMA have been found to be similar for patients with both normal and abnormal airwaysY The FLMA® was specifically designed for use in ear, nose and throat, head and neck, and dental surgery. It has been used for adenotonsillectomy,48 laser pharyngoplasty,49 and dental extraction.50 The device consists of a Classic LMA bowl connected to a floppy, wire-reinforced tube with a slightly narrower bore than the LMA Classic®. The long, flexible, nar­ row bore tube provides better surgical access to the oropha­ ryngeal cavity than the standard laryngeal mask airway. The technique for placement of the FLMA is similar to that for the LMA.

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Ai rway Tec h n i q ues

F I G U R E 1 3-2. The LMA Fastrach® o r I ntu bati n g LMA (I LMA) h a s a r i g i d cu rved meta l a i rway t u be w i t h a m a n i p u lating h a n d l e, a n e p i g l ottic e l evati n g ba r, a d e e p e r bowl, a n d a ra m p that d i rects an e n d otra c h e a l tu be (ETT) up a n d i nto the l a rynx, e n h a n c i ng the success rate of b l i n d i ntubation. In t h i s fig u re, a dedicated wi re­ rei nfo rced s i l icone-ti pped ETT is i n serted i nto the m eta l l u me n of the I LMA. When the h orizonta l b l a c k l i n e on the ETT meets the prox i m a l e n d of the I LMA, the t i p of the ETT wi l l em erge from beneath the e p i g l ottic e l evat i n g ba r.

F I G U R E 1 3-4. Th i s fig u re s h ows the LMA ProSea l® l oa d ed onto the i ntrod ucer. The d ista l e n d of the m eta l i ntrod ucer is p l a ced in an " i n sertion stra p" o n the PLMA and the a i rway tube i s fo l d ed a ro u n d the i ntrod ucer a n d "cl i pped" i nto a proxi m a l matc h i ng s l ot.

F I G U R E 1 3-5. The LMA U n i q u e® i s a s i n g le-use d evice v i rtu a l ly identica l to the Classic with a pert u re ba rs.

F I G U R E 1 3-3. The LMA ProSea l® i n c orporates a d ra i n a g e tu be p l a ced latera l to the a i rway t u be a n d a second dorsa l cuff. The d ra i n a ge tube travel s fro m the proxi m a l end of the device t h ro u g h the bowl o pe n i ng i n to the u pper eso p h a g u s . I t perm its the i n ser­ tion of sta n d a rd na sogastric tu bes to fa c i l itate the d ra i n a g e of g a stric co ntents. Also s h own is the meta l i n trod ucer e m p l oyed to fac i l itate placement of the PLMA.

The reusable LMA Classic• is the original LMA. Variations on the original include: LMA Fastrach•, also known as the Intubating LMA (ILMA) , and also available in a disposable form (Figure 1 3-2) ; LMA Flexible•, similar i n design to the Classic, but incorpo­ rating a non-kinkable, wire-reinforced rube; LMA ProSeal•, a second-generation EGD that has improved seal characteristics and incorporates a gastric drainage capa­ bility (Figures 1 3-3 and 1 3-4) ; LMA Unique•, a single use device virtually identical to the Classic (Figure 1 3-5) ; •

•

•

•

F I G U R E 1 3-6. The LMA Su preme® i s a new d i s posa b l e device that inco rporates the i n sertion advantages of the Fastrach'M and the sea l cha racte ristics of the LMA ProSea i'M.

Ext ra g l ottic Devices fo r Ve nti l ation a n d Oxygenation

• How Is Tracheal I ntubation Performed Using

the I LMA?

- Fixation tab Bite block

- Female drainage port

Tracheal intubation through the ILMA can be achieved blindly. To facilitate the insertion of an ETT through the ILMA, the following steps are recommended: •

•

Cuff •

I nflation -­ l i ne

l

- Pi l ot balloo n Dista l drainage orifice

F I G U R E 1 3-7. The LMA Protector'M i s a new d i s posa b l e s i l icone EG D that i ncorpo rates the sea l and d ra i n a g e c h a ra cte ristics of the LMA ProSea l ® . I t h a s two sepa rate proxi m a l d ra i n a g e ports (a m a l e suction port a n d a fe m a l e d ra i n a g e po rts) w h i c h have d ra i n a g e channel s that r u n d ista l l y i nto a c h a m ber be h i n d the cuff bow l . The cha m ber then na rrows d ista l ly i nto the o rifice at the tip of the cuff which com m u n icates closely with the u p per eso p h a g e a l s p h i ncter. It a l so h a s a n a nato m i ca l ly s h a ped a i rway t u be s i m i l a r to that of the LMA U n iq u e and a b u i lt- i n bite bl ock.

•

•

LMA Supreme•, a disposable second-generation EGO that incorporates the insertion advantages of the Fastrach•, with the seal and drainage characteristics of the ProSeal• (Figure 1 3-6) . LMA Protector, a new disposable second-generation silicone EGO that also incorporates the insertion advantages of the Fastrach•. It has two drainage channels, which emerge as separate ports proximally. It also has a built-in bite block to reduce the risk of obstruction of the airway tube in the event of biting (Figure 1 3-7) .

FASTRACH™ I NTU BATING LARYN G EAL MAS K AI RWAY (I LMA) • What Is the LMA Fastrach®, or I ntu bating

LMA (I LMA), and Why Was It Developed?

While it is possible to intubate the trachea through an LMA, success rates are variable. The intubating LMA (LMA Fastrach•, or Intubating LMA [ILMA] , Teleflex®, Morrisville, NC [Figure 1 3-2] ) was designed by Dr. Brain. The device has a rigid metal curved airway tube with a guiding handle, an epiglottic elevating bar, a deeper bowl, and ramp that directs an ETT up and into the larynx. The device is easy to use, is associated with high success rates of intubation, and has received wide­ spread acceptance. The ILMA is a reusable device, which can be cleaned and sterilized using an autoclave. Single use ILMAs are also available.

•

•

Lubricate the ILMA and the ETT (including the connector of the tracheal tube) with a water-soluble lubricant. Ensure that the ETT slides easily through the ILMA. With the patient in a sniffing position, open the airway by using a head tilt. It should be emphasized that the insertion of an ILMA may be difficult if the inter-incisor gap is less than 20 mm. Grasp the metal handle of the ILMA and insert the device straight back over the tongue to the back of the oropharynx. Then, advance the cuff into the hypopharynx following the palatopharyngeal curve by rotating the device using the metal handle and maintaining gentle pressure against the palate. Once in place, inflate the cuff to achieve a seal for manual ventilation. The metal handle may be used to manipulate the device to achieve a seal to ensure adequate ventilation and oxygenation. The device should be gently rotated in the sagit­ tal plane (commonly known as the "first" Chandy Maneuver) to establish optimally unobstructed ventilation. 5 1 While a number o f ETTs, including the Mallinckrodt Hi-Lo PVC tube®, can be used for tracheal intubation, the dedi­ cated wire-reinforced silicone-tipped ETT supplied with the ILMA has been shown to give the highest success rates. 5 2 With the black vertical line on the tube facing the practi­ tioner, insert the tube into the metal lumen of the ILMA until the horizontal black line on the tracheal tube meets the proximal end of the ILMA metal tube (see Figure 1 3-2) . At this point, the tip of the silicone-tipped ETT is j ust emerging from beneath the epiglottic elevating bar. Resistance will be felt as the silicone-tipped ETT elevates this bar exiting the distal end of the ILMA, and entering the patient's glottis. Tracheal placement is confirmed in the usual manner. Manipulation of the ILMA by lifting the device from the posterior pharyngeal wall using the metal handle (the "sec­ ond" Chandy maneuver) may enhance successful passage in the event of failure. This maneuver helps to prevent the silicone-tipped ETT from colliding with the arytenoids and minimizes the angle between the aperture of the ILMA and the glottis. 53

Some evidence suggests that the ILMA in situ produces sufficient pressure on the posterior hypopharyngeal wall to potentially compromise mucosal blood flow.54 For this reason, except perhaps in an airway rescue or resuscitation situation, it is recommended that the device be withdrawn over the ETT. A stabilizing rod is provided with the ILMA to hold the ETT in position while the ILMA is withdrawn. Many investigators have studied the effectiveness of the blind intubating technique through the ILMA. The reported mean (range) first-time and overall success rate is 73o/o (531 00) and 90o/o (44-1 00) , respectively.54 Several factors that decrease success rates of blind intubation through the ILMA technique have been identified: the use of a #3 ILMA, instead

243

244

Ai rway Tec h n i q ues

of#4 or #5 ILMA, for adult male patients; the application of cricoid pressure; lifting the ILMA handle; the use of a collar; and an inexperienced practitioner. • What Other Tec h n i q ues H ave Been

Described to E n h a nce S u ccess Rates for Tracheal I nt u bation Thro u g h th e I LMA?

Several studies have been published evaluating the effectiveness of a laryngoscope to assist ILMA intubation. The overall success rate appears to be no better than the blind technique. Light­ guided techniques employing a flexible lightwand (Trachlight•) have also been investigated, and have demonstrated improved success rates. 55•56 Lightwand-guided intubation through the ILMA has a first-time and overall success rate of 84% and 99%, respectively.54 Several researchers have shown high suc­ cess rates with a lightwand-guided tracheal intubation through an ILMA. 57, 58 Pandit et al.59 found that bronchoscopic-guided intuba­ tion had a higher success rate (95%) through the ILMA than through the LMA (80%), although the time to intubation was longer with the FB-assisted technique, compared to the blind technique (74 seconds vs. 49 seconds) . Overall, in a range of studies, FB-guided intubation through the ILMA has a first time and overall success rate of 87% and 96%, respectively. However, following a failed blind technique, flexible FB-guided intubation through the ILMA has a success rate of only 86%.54 Agro et al.60 reported the use of a shorter semi-rigid fiber­ optic device, the Shikani Seeing Eye Stylet" (Clarus Medical, Minneapolis, MN) , to facilitate an ILMA intubation. Although tracheal intubation was successful, the investigators commented that the major limitation of the Shikani device was its inability to control the direction of the tip of the device. Using the Patil Intubation Guide" (Anesthesia Associates Inc. , San Marcos, CA) , a whistle diaphragm to detect breath sounds, Osborn61 successfully intubated the trachea through the ILMA under topical anesthesia in a patient with a recent cervi­ cal spine fusion. In 2005, a case series was published describing the successful use of the airway whistle with the ILMA in four patients with known difficult airways.62 • What Are the Indications for the I LMA?

The ILMA alone does not prevent the aspiration of gastric con­ tents, and may produce hypopharyngeal mucosal ischemia if it is left in place for a prolonged duration. Therefore, its role in routine airway management may be limited. However, when used as a temporizing measure, it is a highly effective device in the emergency environment, as an adjunct to a failed or difficult BMV, and as a rescue device in the failed airway. Brain has sug­ gested that the ILMA may not be indicated when the patient is anticipated to be an easy intubation (easy DL) , but may be of considerable benefit when the glottis is high and anterior (diffi­ cult DL) . Furthermore, studies have confirmed earlier findings that ventilation and intubation through the LMA Fastrach" can . dm . o b ese patients. . b e success fiu11y ach 1eve 63 , 64 With respect to Emergency Medical Services (EMS) and prehospital care, the importance of early and effective airway control is universally acknowledged. Tracheal intubation under

DL is associated with a number of practical problems in pre­ hospital trauma, and there is evidence to suggest that the ILMA may play an important role in the pre-hospital setting, in secur. . h a h ead llljury. . . 6 )_ , 66 ing the airway o f trauma patients wit Gercek et al.67 compared the degree of cervical spine move­ ment of three common methods of tracheal intubation in patients with c-spine injuries (DL, ILMA, and FB) using real­ time, three-dimensional ultrasonography in healthy elective sur­ gical patients with manual in-line immobilization. They showed that manual in-line immobilization reduced the cervical spine range of motion during different intubation procedures to a limited extent: the least diminution (i.e., the greatest c-spine movement) occurred with DL (with an overall flexion/extension range of 1 7. 57 degrees) , versus significantly less c-spine move­ ment with ILMA use (overall flexion/extension range of 4.60 degrees) and FB use (overall flexion/extension range of 3 . 6 1 degrees-oral, 5 . 8 8 degrees-nasal) . Furthermore, the mean (± SD) total time required for intubation was shortest for the ILMA ( 1 6. 5 ± 9 .76 seconds) , followed by DL (27.25 ± 8 . 5 6 seconds) , and the longest for both FB techniques (oral: 52. 9 1 ± 56.27 seconds, nasal: 82.32 ± 54.06 seconds) . The prime role of the ILMA lies in managing the airway of patients with a difficult or a failed airway. From a retrospective study involving 254 patients with difficult airways, including patients with C/L Grade 4 views, immobilized cervical spines, stereotactic frames, or airways distorted by surgery or radiation therapy, the clinical experience with the ILMA (both elective and . . 53 68 emergency use) has been 1argeIy positive. The Difficult Airway Society (United Kingdom) guidelines for management of the unanticipated difficult tracheal intuba­ tion in the non-obstetric adult patient without upper airway obstruction include the ILMA. 10.69 · '

LARYNG EAL MASK AI RWAY PROSEAL ® (PLMA) • What Is the PLMA? How Does It Differ from

the LMA?

The PLMA" (Teleflex", Morrisville, NC [Figure 1 3-3] ) is a "second-generation" laryngeal mask airway that incorporates several modifications to the LMA: •

•

•

•

An esophageal conduit is incorporated to provide access to the esophagus and the gastrointestinal tract to minimize the risk of aspiration. This incorporated conduit renders a "dual tube" look to the device. A second cuff on the "dorsal" aspect of the PLMA is intended to enhance the seal characteristics of the device. The PLMA lacks mask aperture bars, and (like the ILMA) has a deeper bowl which makes the migration of the epiglot­ tis into the distal lumen of the device less likely. The PLMA also has a flexible wire-reinforced airway tube to improve flexibility and minimize kinking, and a bite-block to reduce the danger of bite-induced airway obstruction, or tube damage.

The drainage conduit traverses the bowl of the cuff on its way to the upper esophagus, in an effort to reduce the risk of gastric insuffiation when positive pressure is applied to the

Ext ra g l ottic Devices fo r Ve nti l ation a n d Oxygenation

airway. Standard gastric tubes (:::; 1 8 French [Fr] gauge) can be accommodated by the conduit to facilitate gastric decompres­ sion. An accessory vent under the drain tube is intended to prevent the pooling of secretions and can act as an accessory ventilation port?0 Employing moderate force to advance the laryngeal cuff forward into the periglottic tissues may improve the airway seal. The dual tube arrangement seems to reduce the incidence of accidental device rotation during anesthesia. This feature enhances the ability to secure the device in position giving greater confidence for use in longer procedures.

airway pressures suggests malposition of the PLMA. Although air leaks are ordinarily easily detected by auscultation, or by feeling air exiting the drainage tube, a small volume leak is probably best detected by the soap bubble test.76 Three other tests have been suggested to check the patency of the drain­ age tube, including: passing a gastric tube though the drainage tube; passing a FB through the drainage tube; and performing a suprasternal notch tap while observing a soap bubble, or lubri­ cant, at the proximal end of the drainage tube.77 • What Are the Advantages of the PLMA ®,

Compared to the LMA ®?

• How Is the PLMA Placed?

The technique of insertion of the PLMA is similar to that of the LMA. While there is no randomized controlled study comparing the placement technique of the PLMA, with or without a muscle relaxant, it has been shown that successful placement of the PLMA requires deeper anesthesia when compared with the LMA.71 ,72 Three insertion techniques for the PLMA have been advocated: •

•

•

The Introducer Assisted Insertion Technique: Prior to its placement, the PLMA is loaded onto an introducer by plac­ ing the distal end of a metal introducer in an "insertion strap" on the PLMA (Figure 1 3-4) . The airway tube is folded around the introducer and "fitted" into a proximal matching slot. The head and neck of the patient should be placed in a sniffing position. Following the placement of the PLMA, the introducer is removed as the PLMA is held in position. The Digital Technique: Similar to the LMA, the digital tech­ nique involves the placement of the index finger under the insertion strap during the insertion of the PLMA. Rotating the PLMA 90 degrees in the mouth until resistance is felt at the hypopharynx was found to be more successful and associ­ ated with a decrease in blood staining on the device, and in the incidence of sore throat?3 The Tracheal Introducer-guided Insertion Technique: This is probably the most reliable technique to optimally place the tip of the PLMA cuff in the hypopharynx?4 A well-lubricated tracheal introducer (e.g. , an ETI) is placed into the esopha­ gus under direct vision with a laryngoscope. The PLMA is guided into position by placing the tracheal introducer through the esophageal conduit. While this technique enjoys a high success rate, it is time consuming, and probably more stimulating and traumatic.

In a study by Eschertzhuber et al. /5 these three insertion techniques were compared in patients with simulated dif­ ficult laryngoscopy using a rigid neck collar. Insertion was more frequently successful with the ETI technique at the first attempt (ETI-1 00%, digital-64%, Introducer Assisted Technique-6 1 %). The time taken for successful placement was similar among groups on the first attempt. However, it was shorter for the ETI technique after three attempts (ETI-3 1 ± 8 s, digital 49 ± 28 seconds, Introducer Assisted Technique 54 ± 37 seconds) . Proper placement of the PLMA can be confirmed by a num­ ber of techniques. Air leak through the drainage tube at low

In principle, the PLMA would be expected to reduce the aspira­ tion risk when compared to the LMA. Laboratory (and cadaver) evidences are supportive of the theoretical efficacy of the PLMA.78 However, clinical evidence is lacking, largely because the incidence of aspiration of gastric contents with the LMA is so low (0.02%) , and a randomized controlled clinical trial with a large patient population is needed. Aspiration of gastric con­ tents has been reported with the PLMA, and malposition of the PLMA has been identified as a cause of the aspiration?9 The design of the PLMA cuff significantly improves airway seal when compared to the LMA. The larger, softer, wedge­ shaped PLMA cuff enables the anterior cuff to better adapt to the shape of the pharynx.78 Most believe that pressure exerted on the pharyngeal mucosa by the cuffs of LMAs is the cause of sore throat seen with the device. Compared to the LMA, PLMA intra-cuff pressures are lower and airway seal pressure higher for any given intracuff volume.80 Moreover, pressure exerted on the hypopharyngeal mucosa has been found to be below that considered critical for mucosal perfusion. Perhaps the greatest limitation of the use of the LMA in small children is that the seal is often inadequate for PPV, even at high intracuff pressures. This does not appear to be as sig­ nificant a limitation when the PLMA is used in these patients. Multiple studies comparing PLMA and LMA in children showed that first time insertions of PLMA were more success­ ful, had less gastric insufflation, and produced a better seal to allow for PPV compared to the LMA.81-88 • What Are the Disadvantages of the PLMA ®?

It is generally felt that the PLMA is more difficult to place than the LMA. The success rate for first time PLMA insertion is lower than the first time insertion success rate for the LMA (average success rate of 85% with a range from 8 1 % to 1 00% for the PLMA vs. average success rate of 93% with a range of 89% to 1 00% for LMA) .78 It is possible that the insertion dif­ ficulty may, in part, be related to the larger, deeper, and softer cuff of the PLMA. It has been suggested that 20 to 30 insertions of the PLMA are required before competency is achieved.78 • What Are the Potential C l i n ica l Uses

of the PLMA?

The improved airway seal characteristics and touted lower risk of gastric aspiration with the PLMA, compared to the LMA, has expanded its applicability to surgical procedures that would

245

246

Ai rway Tec h n i q ues

not have been considered safe had an LMA been employed. These procedures include laparoscopy,89 open abdominal sur­ gery, surgery in patients with obesity, and in patients with gastroesophageal reflux.78 A study by Hohlreider et al.90 dem­ onstrated less postoperative nausea, vomiting, airway morbid­ ity, and analgesic requirements for the PLMA than the tracheal tube in females undergoing breast and gynecological surgery. The PLMA has been used to provide ventilation and oxy­ genation in patients with a history of difficult laryngoscopic intubation.91 A number of investigators reported the successful use of the PLMA to rescue a failed airway in obstetrical patients after a failed intubation.92-95

While a suction tube may be attached to the male suction port, a well-lubricated gastric tube may be passed through the female drainage port to the stomach. The manufacturer claimed that the drainage channel can be used as a monitor of correct posi­ tioning of the device following insertion, as well as providing continuous monitoring of mask displacement during use. It has an anatomically shaped airway tube similar to that of the LMA Unique•. Therefore, unlike the LMA Proseal•, the LMA Protector"' provides easy insertion without the need for digital or introducer tool guidance as discussed above. It also has a built-in bite block to minimize the risk of the airway tube occlusion in the event of biting .

• What Is the LMA Supreme® and What Is Its

• What Is the Clinical Utility of the LMAP?

Clinical Util ity Compared the PLMA ®?

The LMA Supreme• (Teleflex•, Morrisville, NC) is a disposable, latex free, LMA device with a drainage tube (Figure 1 3-6) . It was designed to combine the desirable features of both the Intubating LMA (ease of insertion, because of the rigid anatomically shaped airway tube made of medical grade polyvinyl chloride) and the PLMA• (higher seal pressures and gastric access) .96 The cuff of the LMA Supreme (LMAS) is designed to provide higher seal pressures than the LMA-Classic• or Unique•. In an early clinical study involving 70 patients, Ali et al.97 reported that the LMAS is superior to the LMA Classic because of its ease of insertion, with low cuff pressure and high oropharyngeal leakage pres­ sure. However, several clinical studies comparing the LMAS and PLMA reported conflicting findings.96•98•99 While both Verghese and Ramaswamy96 and Hosten's et al.98 studies reported that both LMAS and PLMA had similar leak pressures, Lee et al.99 found that the oropharyngeal leak pressure and the maximum achievable tidal volume are lower with the LMAS than with the PLMA. However, there was no difference in the efficacy in venti­ lation and safety between the LMAS and PLMA in these studies. Because of the ease and speed of successful insertion, higher glottic seal pressures, and ability to access gastric con­ tents, Verghese and Ramaswamy96 suggested that the LMAS may have a role in airway management in CPR, and in the "cannot-intubate, cannot-ventilate" (more recently called "cannot-intubate, cannot oxygenate"9) scenario, the ASA Practice Guidelines recommended for the LMA Classic.6•7•100

LARYN G EAL MASK AI RWAY PROTECTOR™ (LMAP) • What Is the LMAP? How Does It Differ from

the LMA Prosea l®?

The LMA Protector'" is a newly introduced single use, silicone second-generation EGD (Figure 1 3-7) . 101 Similar to the LMA Proseal", the LMAP provides access to, and functional separation of, the respiratory and digestive tracts. The LMAP has two sepa­ rate proximal drainage ports (a male suction port and a female drainage ports) , which have drainage channels that run distally into a chamber behind the cuff bowl. The chamber then narrows distally into the opening located at the tip of the cuff which communicates closely with the upper esophageal sphincter.

Since it shares many characteristics of the LMA Proseal" and LMA Unique", the clinical applications of the LMAP would likely be similar to these two second-generation EGDs. However, at the time of writing this chapter, there is no infor­ mation available regarding its effectiveness and safety in pro­ viding ventilation and oxygenation in patients. Furthermore, there is also no information available regarding the suitability for tracheal intubation via the LMAP.

T HE COM SITU SE® (CST) • What Is CST a n d H ow Does It Differ from

the LMA?

The CBT (Tyco-Healthcare-Kendall-Sheridan, Mansfield, MA [Figure 1 3-8] ) is an easily inserted and highly efficacious EGD . It is specified in the ASA Difficult Airway Algorithm as a pri­ mary rescue device in CICO situations.6•7•100 It also has been used successfully during CPR and in trauma patients. 1 02-108 The CBT is a double-lumen airway, one of which is open at borh ends, as wirh a normal ETT. The other consists of an open proximal lumen and a distal blocked lumen, which resembles an esophageal obturator airway. The device has two balloons designed to trap the glottis between them. An oropharyngeal bal­ loon is designed to be positioned just behind the posterior part of the hard palate. Once inflated, this balloon presses the base of the tongue in a ventro-caudal direction and rhe soft palate in a dorso-cranial direction, sealing the oral and nasal airways from behind. Another smaller cuff seals the esophagus once inflated. Perforations between the two balloons in the distally blocked lumen permit the egress of air or oxygen when PPV is applied to a proximal port. Two circumferential rings printed on the proxi­ mal end of the tube indicate that the device has been inserted to the proper depth when the upper teeth or alveolar ridges are situ­ ated between these two marks. The CBT is available in two sizes: the CBT 37F SA (Small Adult) , to be used in patients 4 to 6 feet in height (approximately 120- 1 80 em) ; and rhe CBT 4 1 F, for patients taller rhan 6 feet (approximately > 1 80 em) . • How Is the CST I nserted?

Insertion is facilitated by bending the CBT between the balloons for a few seconds before insertion to mimic the curvature of the pharynx. It is made more pliable if heated to body temperature,

Ext ra g l ottic Devices fo r Ve nti l ation a n d Oxygenation

Although it is rare, ventilation may be impossible through either the proximal or distal lumen. This usually signifies that the CBT has been placed too deeply, with the obturator lumen positioned in the esophagus and the oropharyngeal balloon obstructing the entrance to the larynx. After deflation of the balloons, the CBT should be withdrawn approximately 2.0 to 3 . 0 em. While the CBT may be inserted blindly, the use of a laryngoscope is recommended whenever possible. • What Are the Advantages of the CBT,

Compared to the LMA?

F I G U R E 1 3-8. The Combitu be'M is a d o u b l e-l u m e n a i rway, with o n e l u me n for ventilation a n d the other for access to the G l tract. T h e o ro p h a ryngeal ba l l oon i s desig ned t o be positioned j u st beh i n d t h e posterior pa rt of the h a rd p a l ate sea l i ng both the mouth a n d nose. A s m a l l e r cuff sea l s the eso p h a g u s . Two pri nted r i n g m a rks at the proxi m a l end of the t u be i n d icate a p p ro p riate depth of i n sertion when the u pper teeth or a lveo l a r ridges a re situ­ ated between these two m a r ks.

perhaps attenuating its blunt trauma potential. Placement of the CBT is most readily performed with the patient's head placed in a neutral position, 107 although some practitioners prefer slight extension or flexion. The classical sniffing position is usually not helpful. In the fully awake patient, sedation and topical anesthesia are necessary to ensure that the patient does not react to the insertion. To elevate the tongue and epiglottis, a jaw lift is performed by grasping the lower jaw with the thumb and forefinger. The CBT is inserted blindly along the surface of the tongue with initial gentle downward, curved, dorso-caudal movement, and then directed parallel to the patient's horizon­ tal plane until the printed ring marks lie between the upper and lower teeth, or alveolar ridges in edentulous patients. After insertion, the oropharyngeal balloon of the CBT 37F is inflated with 85 mL of air through a blue pilot balloon. The corre­ sponding filling volume for the CBT 4 1 F is 1 00 mL. Then, the distal balloon is inflated with approximately 1 0 mL of air. With blind insertion, the CBT is successfully placed in the esophagus in more than 95o/o of cases. Ventilation is achieved via the longer blue connector (No. 1 ) , leading to the blocked lumen that contains perforations at the level of the larynx, between the two balloons. The trachea is effectively ventilated because the nose, mouth, and esophagus are sealed by the two balloons. The second "tracheoesophageal" lumen of the CBT can be used for decompression of the esophagus and stomach, thereby minimizing the risk of aspiration. Auscultation of breath sounds over the chest, the absence of gastric insufflation, end-tidal C0 detection, and esophageal 2 detection devices can all assist in the confirmation of correct positioning. 109'1 1 0 Should the CBT enter the trachea o n blind insertion, i t can function like a standard ETT and there will be no need for inflation of the pharyngeal cuff. Ventilation can be achieved through the shorter, unobstructed clear tube (No. 2) leading to the tracheal lumen.

The CBT was designed primarily for use in CPR, 104·105 even by nonmedical personnel. It has been demonstrated to permit effec­ tive ventilation during routine surgery, as well as in the ICU. 103 Most believe that the principal role of the CBT is in emergency airway control when tracheal intubation is not immediately pos­ sible. 1 1 1-1 14 The CBT may be kept in situ for up to 8 hours and allows controlled mechanical ventilation at inflating pressures as high as 50 em H 0 (see aspiration potential below) . The CBT 2 can be replaced by deflation of the oropharyngeal balloon and insertion of an ETT either under DL, or by indirect view using a FB placed anterior, or lateral to the CBT. Several case reports describe the successful use of the CBT in cases of unanticipated difficult airways . 1 1 5-1 17 Thus, it is not sur­ prising that the ASA task force on difficult airway management lists the CBT, along with the LMA and transtracheal jet venti­ lation, as CICO (formerly called CICV) rescue methods.6•7·100 Consequently, the CBT should be part of a portable kit for the management of difficult airways. A major advantage of the CBT over conventional tracheal intubation is that the device can be inserted with the head and neck in a neutral position. Additionally, it requires only mod­ est mouth opening for insertion, and its tubular profile permits insertion in situations that cannot be negotiated by more bulky devices. The CBT can be inserted from a variety of angles, making it useful in awkward environments (e.g. , a patient who is trapped in a vehicle) . The CBT may be of special benefit in patients with massive bleeding or regurgitation, when visualization of the vocal cords is impossible. While protection from aspiration is not abso­ lute, the CBT may be more effective than the LMA Classic® in this regard, due to much higher sealing pressures . 1 1 8 • What Are the Disadvantages of the CBT?

The CBT was not designed to replace other devices for rou­ tine surgery. While the esophageal cuff offers some protection against the reflux of gastric contents into the periglottic area, the level of protection against aspiration does not approach that of a cuffed ETT. The suctioning of tracheal secretions is very difficult when the CBT is in the esophageal position. To address the issue of secre­ tions and suctioning, Krafft et al. 1 19 proposed a modification in the CBT, in which the two anterior, proximal perforations of the CBT are replaced by a single, larger, ellipsoid-shaped hole that allows for fiberoptic access of the trachea, tracheal suction­ ing, and tube exchange over a guide wire. It should be noted that FBs (e.g. , Storz, Tuttlingen, Germany) with a small outer

247

248

Ai rway Tec h n i q ues

diameter (3.0 mm OD) allow passage through the unmodified pharyngeal perforations. Contraindications to the use of the CBT include: an intact gag reflex, airway obstruction by foreign bodies, tumors, or swelling, the presence of known esophageal disease, and the prior ingestion of caustic substances. Complications associated with the use of CBT have been reported. 1 20•1 2 1 In a retrospective study of 1 1 39 patients requir­ ing resuscitation using the CBT, four cases of subcutaneous emphysema, pneumomediastinum, and pneumoperitoneum associated with the CBT during prehospital management were reported. 1 2 1 The reason for these complications appeared to be hyperinflation of the distal balloon (20 - 40 mL) , although external chest compression and continuous PPV may also have been factors. Other rare complications include transient cranial nerve dysfunction, 1 22 esophageal rupture, 1 23 and tongue engorgement. 1 24

F I G U R E 1 3-9. The La ryng e a l Tu be Ai rway consists of a s i l icone a i rway t u be with two ve ntilation outlet perforations lying between two cuffs, a s i n g l e p i l ot ba l l oo n and a 1 5- m m male a d a pter.

• What Is the LT and How Does It Differ from

ischemic mucosal damage. Two ventilation outlets are located between the two cuffs, in the anterior aspect of the tube. The proximal outlet is "protected" by a "V"-shaped deflection in the pharyngeal cuff, such that when with the cuff is inflated, soft tissue is deflected from this opening, helping to maintain a patency. There are two side holes near the distal outlet. Even though the two cuffs are supplied by a single infla­ tion pilot balloon apparatus, the design of the inflation system allows the pharyngeal cuff to fill first, stabilizing the position of the tube. 1 2 5 Once the pharyngeal cuff has molded to the anat­ omy of the patient, the esophageal cuff inflates. The amount of air for cuff inflation is specific to tube size and is indicated on a syringe that is included in the package. Six sizes, suitable for neonates up to large adults, are available. 1 26 Safe inflation of the dual cuffs may be enhanced with the aid of a cuff pres­ sure gauge and ought to be limited to 60 em H 0. In a recent 2 report, an overinflation of the LT in a difficult pre-hospital air­ way management of a patient with Down syndrome resulted in a clinical misdiagnosis of Ludwig's angina in the Emergency Department, necessitating an emergency tracheotomy. 1 27 There are several versions of the laryngeal tube: standard laryngeal tube•, disposable laryngeal tube• (LT-D) , laryngeal tube-Suction II" (LTS) , and disposable laryngeal tube-Suction II" (LTS-D) . 1 26 Similar to the PLMA, the LTS-D has two lumens: one for ventilation and the other serves as a conduit to the esophagus and stomach.

The laryngeal tube airway• (VBM Medizintechnik, Sulz am Neckar, Germany [Figure 1 3-9] ) , also known as the King LT Airway• in North America, is an EGD that was introduced to the European market in 1 99 9 . 1 2 5 It is similar in appearance and function to the CBT, and is available in three configurations (see below) . The fundamental configuration of the LT is a silicone airway tube with ventilation outlet perforations lying between two cuffs, pharyngeal and esophageal. As opposed to the CBT, the LT has a single pilot balloon connected to both cuffs, and a single 1 5-mm standard male adapter. The airway tube is short and "]" shaped with an average diameter of 1 . 5 em leading to a blind tip. The device requires a mouth opening of at least 23 mm for its insertion. After device placement, the proximal cuff should lie in the hypopharynx and the distal cuff in the upper esophagus. Both cuffs are high volume low pressure in design to establish an adequate seal, while minimizing the risk for

An appropriately sized LT should be selected based on the patient's weight and height. Prior to insertion, the cuffs should be completely deflated and well lubricated. The device should be inserted with the patient's head and neck in a "sniffing" position. 1 26 The head is extended on the neck with the non­ dominant hand, to open the mouth. The LT is then inserted blindly in the midline, with the tip pressed against the hard palate, and then advanced along the palate into the hypophar­ ynx until resistance is felt, at which point a proximal horizontal black line should be aligned with the front teeth. The device is usually easily inserted with insertion times comparable to those reported for the LMA. 1 2 8 The device provides a patent airway in the majority of patients following the first insertion attempt and success does

• What Are the Potential Clinica l Uses of

the CBT?

The CBT is an easy-to-use, rapidly inserted emergency airway device that has performed satisfactorily in many circumstances. It is accepted as a primary rescue device in CICO situations, as well as for CPR, and in trauma patients. The CBT has been recommended in the Practice Guidelines for Management of the Difficult Airway of the ASA.6•7•100 It has also been recom­ mended in the "Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiac Care" of the AHA. In 2000, the CBT was upgraded by the AHA as a class Ila device. Furthermore, the CBT may provide an element of protection in patients at risk for aspiration, and it may be of benefit for patients in whom manipulation of the cervical spine is hazardous or impossible. Successfully placed, the device is capable of facilitating adequate ventilation and oxygenation, and in most instances is as effec­ tive as endotracheal intubation. 106

LARYN G EAL TUBE® (KI NG LT AI RWAY® [LT]) the LMA?

• How Is a LT Inserted?

Ext ra g l ottic Devices fo r Ve nti l ation a n d Oxygenation

not require extensive training. 1 29'130 Indicators of correct place­ ment include end-tidal carbon dioxide detection, auscultation of bilateral breath sounds, absence of gastric insuffiation, and adequate chest movement. Capnographic waveform analysis may be of particular use in confirming proper position of the LT. A brief period of PPV may also confirm proper alignment of the LT and the absence of obstruction. The LT should be removed with the patient either deeply anesthetized, or totally awake. In an awake patient, the LT should be removed only when airway protective reflexes have completely returned. • What Are the Advantages of the LT,

Compared to the LMA and the CBT?

Insertion of this device is relatively easy and successful in most patients on the first attempt. The soft tip minimizes mechanical trauma on insertion and high-volume/low-pressure cuffs pro­ vide a good seal and protection against mucosal ischemic dam­ age. A single pilot balloon confers an element of simplicity and speed in emergency situations. Other advantages of LT include: •

•

•

•

The adequacy of ventilation with the LT is comparable to that obtained with other EGDs. The ease of insertion and high quality of the seal achieved may confer a preferred role for the LT in airway management during CPR. 1 2 9 The LT can be used successfully in children as young as 2 years old, with superior seal pressures and equivalent ease of insertion. 131 The esophageal cuff of the laryngeal tube may provide an element of protection against the reflux of gastric contents into the periglottic area and the tube-Suction options permit gastric decompression. Both of these features may reduce the risk of aspiration, relative to the LMA Classic®. 132, 133 Due to the form and length of the device, an unintended tracheal intubation should not occur.

• What Are the Disadvantages of the LT? •

•

•

•

•

•

Protection from aspiration is less than that offered by a cuffed ETT, and in high aspiration risk situations tracheal intubation remains necessary. While the newer laryngeal tube-Suction II (LTS) , and the disposable laryngeal tube-Suction II (LTS­ D) may have the potential to provide some protection from aspiration, presently there are no clinical data available. The intracuff pressure may increase by as much as 1 5 em H 0 within 30 minutes after its insertion if nitrous oxide 2 is employed, due to the diffusion of this gas into the cuff. Manometric monitoring of the cuff pressure has been suggested. 134 Position adjustments to ensure continuing airflow continuity may be required more frequently in obese patients. 135 PPV through the LT may provide inadequate ventilation in patients who require high pulmonary inflation pressures. The mouth opening required for LT insertion is at least 23 mm. As with any EGD, the LT may not be effective in the pres­ ence of anatomic distortion of the upper airway, such as lesions of the epiglottis or laryngopharynx.

•

The LT is less effective than the LMA Classic• in children younger than 1 0 with respect to ease of ventilation and endo­ scopic view through the device. 136

• What Are the Potential C l i n ica l Uses

of the LT?

In anesthetic practice, the LT can be used in patients who are candidates for face mask or LMA delivered anesthesia. It may also find a role in the failed airway, similar to that of the LMA and the CBT. The dimension and position of the ventilation holes and the protection offered by the overhanging cuff block permit the insertion of a suction catheter, ETT exchange device, FB, or an ETI, over which an ETT may be passed.137

LARYVENT® (LV) • What Is the LV and How Does It Differ from

the LMA?

The LV (B+ P Beatmungs-Produkte GmbH, Seelscheid, Germany) consists of a single tube with a standard male con­ nector, two cuffs with a single pilot balloon, and a ventilation outlet. The superior cuff lies in the hypopharynx and the ven­ tral part of the cuff contains the orifice for ventilation. The inferior cuff is smaller and should lie at the level of the upper esophageal sphincter. As with other EGDs, the insertion of the LV is a blind technique and appears to have a rapid learning curve, similar to that of the LT. • How Do You Insert the LV?

Prior to the use of the LV, the cuffs should be tested by inflat­ ing 50 mL of air. During insertion, the tip of the LV should be introduced along the posterior wall of pharynx and advanced until resistance is felt. The cuffs should then be inflated with 50 mL of air. If there is resistance to filling, the LV has been introduced too deeply and should be retracted two to three em before reattempting cuff inflation. • What Are the Advantages of the LV,

Compared to the LMA?

The advantages of the LV are similar to those of the LMA­ Unique®, and LT, with comparable provision of ventilation and oxygenation, at least in early clinical experience. 1 2 9'138 • What Are the Disadvantages of the LV?

More complex handling, resulting in a significantly higher fail­ ure rate, and postoperative patient discomfort suggest that the LV may not be the first choice in routine anesthesia practice. 138 • What Are the Potential C l i n ica l Uses of

the LV?

The role and advantage of the LV are similar to those of the LT. The precise advantages have not yet been defined by clinical trials.

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Ai rway Tec h n i q ues

AI RWAY MANAGEMENT DEVICE® (AMD) • What Is the AMD and How Does It Differ

from the LMA?

The AMD (Nagor Limited, Isle of Man; manufactured by Biosil Ltd, Cumbernauld, UK [Figure 1 3- 1 0] ) consists of a clear sili­ cone dual lumen tube that is concave ventrally with inflatable oropharyngeal and hypopharyngeal cuffs. An oval ventilation port is located in the ventral part of the device opposite the laryngeal inlet. The connector at the proximal end of the tube is Y-shaped incorporating two ports: one for anesthetic gas deliv­ ery and providing access for suction catheters, a FB or an ETI; and the second for a channel into the esophagus for suction. When fully inflated, the upper cuff fills, elevating the tongue and epiglottis. The cuffs have independent inflation controls, which are color-coded. The shape of the cuffs ensures correct orientation in the airway and prevents both lateral movement and rotation of the tube. The AMD is available in several sizes: 3 . 0 to 3 . 5 for patients weighing 30 to 60 kg, and size 4.0 to 5 . 0 for patients more than 60 kg.

• What Are the Advantages of the AMD

Compared to the LMA?

A key feature of this device lies in the access it provides to the esophagus when the esophageal cuff is partially deflated. A suc­ tion catheter can be introduced through the device without interrupting ventilation to aspirate the esophagus, and provides an element of protection against aspiration. • What Are the Disadvantages of the AMD?

Compared with other EGDs, the AMD device is somewhat difficult to insert and airway trauma is possible. 139.141 Cook et al. 1 39 reported a first-time success rate of 66% in estab­ lishing an airway, with an average of 0 . 5 6 manipulations per patient and a primary failure rate of 1 1 . The AMD also had an increased incidence of loss of airway during anesthesia. 142 While the AMD may provide protection against aspiration, presently there are no data to support the claim. • What Are the Potential C l i n ica l Uses of

the A MD ?

• How Is the AMD Inserted ?

The insertion technique is similar to other EGDs. Both cuffs of the AMD should be well lubricated, the pharyngeal cuff should be fully deflated, and the esophageal cuff should have 5 . 0 to 9.0 mL of air. This closes the esophageal cuff channel through a unique constriction mechanism and permits atraumatic inser­ tion. The AMD, held in the dominant hand, is inserted in the midline of the mouth in a caudal direction until it seats prop­ erly in the hypopharynx. The pharyngeal cuff is then inflated with 50 to 80 mL of air. Like all EGDs, proper placement should be confirmed after insertion.

F I G U R E 1 3- 1 0. The Ai rway Ma nagement Device'M is a c l e a r s i l icone t u be with hypo p h a ry n g ea l a n d o ro p h a ryngeal cuffs. An ova l h o l e l ocated between the two cuffs i n the ventra l pa rt of the device a l l ows venti lation.

While the dynamic relationship between the hypopharyngeal cuff and the esophageal suction port is interesting, the precise advantage of the AMD is difficult to define at this time.

PERI LARYNG EAL AI RWAY (Cobra PLA® [CPLA]) • What Is the CPLA and How Does It Differ

from the LMA?

The CPLA (Engineered Medical Systems, Inc., Indianapolis, IN [Figure 1 3- 1 1] ) consists of a breathing tube with a cir­ cumferential inflatable cuff proximal to a ventilation outlet, a 1 5-mm standard adapter, and a distal widened cobra-shaped head designed to separate soft tissues and to allow ventilation of the trachea. Once in place, the cobra head lies in front of the laryngeal inlet. Internal to the cobra head, a ramp directs ventilation into the trachea. A soft grill shields the inferior aperture of the device in an attempt to deflect the epiglottis

F I G U R E 1 3- 1 1 . The Cobra P LA'M con s i sts of a breath i n g t u be with a c i rcu mferenti a l i nfl ata b l e cuff proxi m a l to the ventilation outlet portion, a 1 5- m m sta n d a rd a d a pter, and a d i sta l widened "Co bra head" desig ned to sepa rate the soft tissues of the hypo p h a rynx and permit ve nti lation .

Ext ra g l ottic Devices fo r Ve nti l ation a n d Oxygenation

anteriorly. The bars of the grill are sufficiently flexible to permit an ETT to pass easily. The cuff is shaped such that it resides in the hypopharynx at the base of the tongue and, when inflated, raises the base of the tongue exposing the laryngeal inlet and affects an airway seal. The unique shape of the distal part of the device allows it to slide easily along the hard palate during insertion, and to move soft tissues away from the laryngeal inlet once in place. The CPLA is available in eight sizes and it can be used in small children, including neonates. 143 Size selection is gov­ erned by the weight of the patient. Generally, #3 is used in most female patients, #4 for most men, and #5 for larger men. When one is unsure which size is best, or when learn­ ing placement technique, selecting the lower size is recom­ mended. In general, larger sizes required considerably higher cuff pressures to produce an acceptable seal compared to the smaller sizes. 144 Several modifications of the original design of the CPLA have been introduced. 143 The second-generation CPLA has a distal curve in the breathing tube to avoid kinking, and softer material to facilitate insertion and minimize trauma. The Cobra PLus• has a temperature probe to measure core tem­ perature and a gas sampling line for the three smallest pedi­ atric sizes. • How Do You Insert the CPLA?

The CPLA is simple to insert, though somewhat more difficulty is encountered in the obese. 145 Prior to insertion, the pharyngeal cuff is fully deflated and folded back against the breathing tube. The back of the cobra head and cuff are lubricated, taking care that the lubricant does not obstruct the grille. The patient's head is placed in the sniffing position. A jaw lift is performed and the distal end of the CPLA is directed straight back through the mouth between the tongue and hard palate. Modest neck extension (without a jaw lift maneuver) may aid the passage of the device as it turns toward the glottis at the back of the mouth. Once the CPLA traverses the back of the mouth, it usu­ ally turns caudally toward the larynx with minimal resistance, as the flexible distal tip guides the device downward. The CPLA is properly seated above the glottis when modest resistance to further distal passage is encountered. Once inserted, the flexible tip lies behind the arytenoids, the cuff lies in the hypopharynx at the base of the tongue, and the ramp lifts the epiglottis. Then the cuff is inflated until the leak with PPV disappears. Indicators of correct placement are absence of leak on auscultation of the neck, bilateral breath sounds, absence of gastric insufflation, easily produced chest movement, and positive carbon dioxide detection. Exceeding a peak airway pressure of 25 em H 0 with 2 PPV is not recommended, even when testing for ventilation and cuff seal, because of the risk of gastric insufflation. If the CPLA is not inserted far enough, inflation of the cuff may cause the tongue to protrude from the mouth of the patient. In this situation, the cuff should be deflated and the device advanced further, or a smaller sized CPLA selected. It is possible to advance the cobra head beyond the laryngeal inlet, in which case ventilation will not be possible. The CPLA should be removed awake, with the airway protective reflexes intact.

• What Are the Advantages of the CPLA,

Compared to the LMA?

The tube of the CPLA has a larger lumen than most EGOs and may be particularly useful in directing flexible endoscopic assisted tracheal intubation, 146•147 especially when larger ETTs are indicated. An ETT of 8.0 mm 10 can be advanced through the sizes 4 to 6 CPLA. 143 In addition, it has been made short enough that its removal after insertion of an ETT is greatly facilitated. Although less reliable, blind tracheal intubation through the CPLA using a generic ETT introducer (e.g., the ETI) may be possible. Like many other EGOs, the insertion technique is simple and has been accomplished by personnel with little or no expe­ rience. Several small clinical studies reported that the CPLA has better airway sealing characteristics compared to the LMA. 148• 149 During gynecological laparoscopy, the CPLA provided similar insertion characteristics, but higher airway sealing pressures than the LMA-Classic. 150 However, Park et al. 151 showed that gastric insufflation, or ventilatory difficulty, may occur follow­ ing the change of the position of the head and neck when using the Cobra-PLA, as compared to PLMA. Khan et al. 15 2 reported successful use of the CPLA for venti­ lation following failed attempts in placing an LMA in patients with face and neck contractures, as well as limited mouth opening. • What Are the Disadvantages of the CPLA?

In comparison trials with LMA Classic• and LMA-Unique®, the CPLA took slightly longer to insert and macroscopic blood occurred more frequently on the CPLA, seen on up to 40% of the devices after removal. 146•148·150 Although blood staining has been detected more frequently with the CPLA compared with other EGOs, there were no differences in airway morbidity. 153 Therefore, the clinical significance of these findings is uncertain. The CPLA is not appropriate for patients with low lung compliance or increased airway resistance. The major disadvan­ tage of the device is that it does not protect against aspiration and does not secure the airway as effectively as an ETT. 154 The mask aperture bars probably have no anatomical utility, and predispose to herniation of the pharyngeal structures on inser­ tion and while in situ. 153 Although it is rare, aspiration associated with use of the CPLA has been reported. 154•155 In fact, Cook and Lowe154 ter­ minated the CPLA evaluation study after two cases of serious pulmonary aspiration with the use of the CPLA, suggesting that the CPLA should be avoided in patients at risk of aspiration.

THE STREAM L I N E D PHARYNX AI RWAY L I N E R (S L I PA®) • What Is the SLIPA and How Does It Differ

from the LMA?

The SLIPA (SLIPA Med, Cape Town, South Africa [Figure 13-12] ) is a disposable EGO. It is designed for airway manage­ ment during controlled ventilation. 1 56•157 The peculiar shape of the device provides a seal without the use of an inflatable cuff.

251

252

Ai rway Tec h n i q ues

• What Are the Potential Clin ical Uses of the

SLIPA Device?

Based on the current available evidence, the SLIPA appears to have comparable efficacy and complications as the LMA, and may be used as a primary airway device for short surgical procedures. 143

F I G U R E 1 3- 1 2. The S L I PA™ i s s h a ped l i ke a h o l l ow boot with "toe;' "bridge;' a n d "heel" pro m i n e n ces, designed to e n g a g e the patient's pha rynx. The h o l l ow d e s i g n fea t u re perm its the entra pment of l i q u i d s s u c h as secretions, b l ood, a n d g a stric fl u i d s, t h u s preventing a s p i rati o n .

The body of the SLIPA is shaped like a hollow boot with "toe," "bridge," and "heel" prominences, designed to engage the mucosal lining of the patient's pharynx. Its hollow config­ uration and shape permit the entrapment of secretions, blood or gastric contents in the device, theoretically reducing the risk of aspiration. The device is formed from soft plastic mate­ rial, flexible enough to allow easy insertion. The hollow cham­ ber flattens to facilitate insertion. After placement, the "toe" should sit in the hypopharynx. The "bridge," with its two lat­ eral bulges, fits into the pyriform fossae, displacing tissue away from the posterior pharyngeal wall. The "heel" of the chamber anchors the SLIPA in position by sliding over the soft palate and into the nasopharyngeal opening. Toward the toe side of the bridge are smaller lateral bulges that coincide with the inferior comus of the hyoid bone designed to relieve pres­ sure on relevant nervous tissue, such as the superior laryngeal branch of the vagus. • How Is the SLIPA Inserted?

The S LIPA is inserted similarly to the LMA. The patient's head and neck should be placed in a sniffing position. Held in the dominant hand, the SLIPA is inserted in the mid­ line of the mouth, pressed against hard palate, and advanced until resistance is felt. A j aw lift may facilitate placement. The crescent shape of the toe minimizes the risk of down­ ward folding of the epiglottis, which may lead to airway obstruction. The toe of the device slips easily into the esoph­ agus, where it creates a seal . Kang et al. 158 reported that pre­ warming of the S LIPA appeared to improve fitting of the laryngeal structure. After placement, the SLIPA returns to its pre-insertion shape.

T HE Ambu® AuraOnce™ DISPOSABLE LARYNG EAL MASK • What Is the Ambu® AuraOnce™ Disposable

La ryngeal Mask (ALM) and How Does It Differ from the LMA?

Unlike the reusable LMA Classic", the Ambu" AuraOnce'" Laryngeal Mask (Ambu", Ballerup, Denmark [Figure 13-13] ) is a disposable EGD . 160 It i s made o f polyvinyl chloride with an extra soft 0.4-mm cuff, providing a better seal that con­ forms well to the shape of the airway. 161 Similar to the LMA Supreme", it incorporates a 70° preformed curvature that rep­ licates natural oropharyngeal anatomy to facilitate insertion.162 Unlike the LMA Classic" and LMA Unique", the bowl of the mask lacks the aperture bars and therefore it would be easier to perform tracheal intubation through the airway tube of the ALM. The two horizontal lines on the airway tube can be used as indicators of proper depth of insertion of the ALM. The ALM has eight different sizes (size 1 and 1 Y2 for infants, size 2 and 2Yz for children, and size 3 to 6 for adults) . Since the introduction of the Ambu" AuraOnce'" Laryngeal Mask in 2004, three other versions of Ambu" Laryngeal Mark have been introduced: ( 1 ) Ambu" Aura-l'" Disposable Laryngeal Mask has the intu­ bating capability using standard ETTs (Figure 1 3 - 1 4) . (2) Ambu" AuraFlex'" Disposable Laryngeal Mask i s a dispos­ able laryngeal masks by incorporating a non-kinkable, wire-reinforced airway. It is similar in design to the reusable LMA Flexible".

• What Are the Advantages and

Disadvantages of the SLIPA, Compared to the LMA?

A systematic review and meta-analysis comparing SLIPA and LMA showed no difference between ease of insertion, oro­ pharyngeal leak pressure, and quality of fibreoptic view of the larynx. SLIPA insertion did have a higher incidence of blood­ staining after removal. 159

F I G U R E 1 3- 1 3. The A m b u ® A u raOnce'M La ryng e a l Mask.

Ext ra g l ottic Devices fo r Ve nti l ation a n d Oxygenation

Another advantage of the ALM over the LMA Classic• is the lack of aperture bars. In other words, tracheal intubation (either blindly or with the guidance of a FB) can be easily performed through the airway tube of the ALM following an airway rescue in a CICO situation. • What Are the Potential C l i n ica l Uses of

the ALM?

To investigate the clinical uses of ALM, a number of studies have been conducted during the last decade. In a meta-analysis conducted by Baidya et al. , 163 the investigators concluded that that the Arnbu• AuraOnce'M Laryngeal Mask is similarly effec­ tive as the LMA Unique• and LMA Classic• and may be easier to insert than the other two devices. The incidence of compli­ cations associated with the use of the ALM is generally low. 160

iGEL® • What Is the iGel® and How Does It Differ

from the LMA?

F I G U R E 1 3- 1 4. A m b u ® Aura-I'M D i s posa b l e La ryngea l M a s k h a s the i ntu bati n g c a pa b i l ity u s i n g sta n d a rd ETTs.

(3) AuraGain'" Disposable Laryngeal Mask is Arnbu's latest laryngeal mask, by integrating gastric access and intubation capability in an anatomically curved single-use device that facilitates rapid establishment of a safe airway. • How Is the ALM Inserted?

The insertion technique is similar to other EGDs. The cuff should be fully deflated and lubricated. The head of the patient should be placed in the "sniffing position." While many inser­ tion techniques have been described, the manufacturer recom­ mends the "pencil insertion technique." 162 The airway tube is held by the dominant hand like a flute, with three fingers placed above the j unction of the cuff and the tube and the thumb on the vertical line on the airway tube. As the tip of the cuff is placed inside the mouth, the ALM is inserted inward with a circular motion, pressing the contours of the hard and soft palate, and the ALM is then advanced into the hypophar­ ynx until resistance is felt. The ALM is inserted correctly when the patient's incisors are between the two horizontal markings on the airway tube. The cuff is then inflated with sufficient air to obtain a seal, equivalent to intracuff pressures of approxi­ mately 60 em H 0. Like all EGDs, proper placement should be 2 confirmed after insertion. • What Are the Advantages of the ALM

Compared to the LMA?

According to the meta-analysis conducted by Baidya et al. , 163 device insertion is significantly faster with the ALM than with the LMA Unique•, bur similar to the LMA Classic•. The ALM also provides an oropharyngeal leak pressure higher than with the LMA Unique• and equivalent to that of the LMA Classic•. 163

The iGel" (Intersurgical Ltd., Wokingham, UK) is a single-use EGD that is made of a thermoplastic elastomer gel. It has a noninflatable cuff that can anatomically seal the pharyngeal, laryngeal, and perilaryngeal structures, with a minimal risk of compression trauma. The device has an elliptical cross­ sectional shaped tube with a slight curve longitudinally, to facilitate insertion and minimize axial rotation once it is placed (Figure 13- 1 5) . It also has an independent gastric drain tube and an integral bite block. It is single use and available in sizes 3 to 5 . A size 4 is recommended by the manufacturers for patients between 50 kg and 90 kg, making it the most common size for the normal adult population. • How Is the iGel® Inserted?

With the patient's head and neck placed in a "sniffing position," the well-lubricated iGel• is placed in the mouth and passed along the posterior pharynx until resistance is felt. 164 Insertion does not require an introducer or placement of the finger into the mouth, as the device is simply pushed into place. A 4SO "twist" can be employed to facilitate insertion. The cuff does not require inflation of air following placement. • What Are the Advantages of the iGel®,

Compared to the LMA?

The insertion process requires one fewer step, as there is no air required for cuff inflation. The elastomer gel may provide a more efficient seal around the larynx after warming to body temperature. 165 In addition, the gel-filled cuff may potentially cause less direct trauma or pressure damage to the oropharyn­ geal mucosa. Unfortunately, at present, there are no clinical data to confirm this potential advantage. The iGel" has a gastric drain tube that may offer added pro­ tection against the aspiration of regurgitated stomach contents. Two separate case reports have confirmed that this drainage tube provided protection against aspiration. 165•166 However, in

253

254

Ai rway Tec h n i q ues

• What Are the Clin ical Uses of the iGel®?

F I G U R E 1 3- 1 5 . The iGel device h a s a n o n i nflata b l e cuff a n d a n e l l i ptica l cross-sect i o n a l - s h a ped t u be with a s l i g h t cu rve l o n g itudi­ nally to fac i l itate i n serti o n . In add ition, it a l so h a s a n i n d e pendent gastric d ra i n tube a n d a n i nteg ra l bite b l ock.

a case series of 280 patients reported by Gibbison et al. , 167 three patients had regurgitation while using the iGel•. Although the iGel completely protected the airway from aspiration of regur­ gitated stomach contents in two of these patients, it did not provide complete protection in the third patient. The investi­ gators concluded that the efficacy of the drainage tube has not been confirmed, and further study is required to determine the safety profile of the device. • What Are the Disadvantages of the iGel®?

In a clinical evaluation study with 1 00 patients, Gatward et al. 168 found that the airway seal offered by the iGel is infe­ rior to other EGDs, such as the PLMA. In a cadaver study, Schmidbauer et al. 169 showed that both the PLMA and LMA Classic• provided a better seal of the esophagus than the iGel• airway. If there is a leak around the iGel•, it may have to be replaced with a different size, since there is no option of adding or withdrawing air from the cuff. The drain tube of the iGel• is significantly smaller than the drainage tube of the PLMA. For instance, a French gauge 1 2 catheter can b e inserted through the size 4 iGel• compared to a 1 6-F catheter for a size 4 PLMA. 168 It is unknown if the smaller drain tube is adequate to provide equivalent protec­ tion of aspiration, compared with other EGDs with a larger drainage tube.

Compared with seven other extraglottic airway devices (Airway Management Device•, CobraPLA•, Combitube•, Laryngeal Tube•, Laryngeal Tube Disposable• [LTD] , Laryngeal Tube Suction W [LTS II] , and the SLIPN) , the iGel• has been shown to perform the best for ease of insertion into the airway during training on manikins by ten anesthesiologists. 1 70 In a clinical evaluation study involving 1 00 patients, Gatward et al. 168 reported that the iGel• was successfully inserted in all patients and allowed effective controlled ventilation in 98%. The investigators also commented that, while the airway seal offered by the iGel• may be inferior to other EGDs, such as the PLMA, it is still sufficient for controlled ventilation in the vast majority of patients. Rates of failure, manipulations required, and com­ plications were also very low for the iGel• in that study. Another prospective observational study with 71 patients, Richez et al. 171 confirmed the efficacy and safety of the iGel• airway device. The iGel• has been successfully used to provide ventilation in patients with a difficult airway in a number of case reports. Michalek et al. 1 72 reported successful placement of the iGel• under general anesthesia in two uncooperative patients with an anticipated difficult intubation (Hunter's and Waardenburg Syndromes) . Oxygenation and ventilation were maintained using the iGel•, which was then used as a conduit for tracheal intubation using a pediatric FB. Joshi et al. 173 reported the use of the iGel• as an airway res­ cue in a patient with scleroderma and predicted difficult intu­ bation. Under general anesthesia, ventilation was difficult with a bag mask, the LMA Classic•, and the PLMA, but ventila­ tion was achieved easily with a size 4 iGel•. Others have also reported the use of the iGel• as a rescue airway device. 174 In the EMS systems in the United Kingdom, an EGD (the PLMA) was introduced into clinical practice as an alternative to emergency cricothyrotomy for the management of failed intubation in 200 5 . 175 The PLMA was initially chosen for the potential ability to ventilate as well as the presence of a gas­ tric drainage channel to minimize aspiration. But, the iGel has replaced the PLMA in 20 1 0 for the ease of insertion. 175

S U M MARY During the last two decades, EGDs, such as the LMN and the Combitube•, have been shown to be effective and safe devices for delivering effective oxygenation and ventilation. In addition, many studies have shown that these devices can be used suc­ cessfully to "rescue" patients with a failed airway. These devices are recommended for this indication by authorities, such as the ASA (ASA Difficult Airway Management Algorithm) , the Difficult Airway Society (United Kingdom) , and the Canadian Airway Focus Group. The major disadvantage of all EGDs is their inability to completely seal the larynx and protect against aspiration. In addition, poor seal by any of these devices can lead to air leak on PPV and gastric insufflation. Newer designs of EGD, such as the Intubating LMA (or LMA Fastrach•) , LMA Proseal•, LMA Supreme•, LMA Protector'M, King LTS-D•, and iGel• have been developed to attempt to address these concerns.

Ext ra g l ottic Devices fo r Ve nti l ation a n d Oxygenation

As a result of the widespread acceptance and popularity of the original LMA, many newly designed reusable and dis­ posable EGD devices have been introduced. There are no less than 25 EGDs currently available. 1 1 Although many prelimi­ nary clinical studies have demonstrated the efficacy and safety of these devices, most of them involved only a small number of patients. More clinical studies with larger patient popula­ tions are needed to confirm these findings. Finally, these devices are not only effective airway management and airway rescue devices, but can also be used and learned easily, in contrast to BMV and endotracheal intubation. It is entirely reasonable to expect that these devices will supplant BMV as a rescue airway maneuver.

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A new supraglottic airway device: LMA-supreme, comparison with LMA-Proseal. Acta Anaesthesia! Scand. 2009 ; 5 3 (7) : 8 52-857. 99. Lee AK, Tey JB, Lim Y, Sia AT. Comparison of the single-use LMA supreme with the reusable ProSeal LMA for anaesthesia in gynaecological laparoscopic surgery. Anaesth Intensive Care. 2009;37(5) : 8 1 5-8 1 9.

Ext ra g l ottic Devices fo r Ve nti l ation and Oxygenation 1 00. American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Practice guidelines for the difficult airway. Anesthesiology. 1 993;78 (3) : 5 97-602. 1 0 1 . LMA Protector'": Instructions for use. Product Monogram. In: Teleflex Medical M, NC, USA, ed. 20 1 5 . I 02. Agro F, Frass M, Benumof JL, Krafft P. Current status of the Combitube: a review of the literature. j Clin Anesth. 2002; 1 4 (4): 307-3 1 4 . I 03. Frass M, Frenzer R , Mayer G, Popovic R , Leithner C. Mechanical ventila­ tion with the esophageal tracheal combirube (ETC) in the intensive care unit. Arch Emerg Med. 1 987;4 (4) : 2 1 9-22 5 . 1 04. Frass M, Frenzer R , Rauscha F, Schuster E, Glogar D. Ventilation with the esophageal tracheal combitube in cardiopulmonary resuscitation. Promptness and effectiveness. Chest. 1 988;93(4) :78 1 -784. 1 0 5 . Frass M, Frenzer R, Zdrahal F, Hoflehner G, Porges P, Lackner F. The esophageal tracheal combirube: preliminary results with a new airway for CPR. Ann Emerg Med. 1 987; 1 6 (7) :768-772. I 06. Frass M, Rodier S, Frenzer R, !lias W, Leithner C, Lackner F. Esophageal tracheal combitube, endotracheal airway, and mask: comparison of venti­ latory pressure curves. ] Trauma. 1 989;29( 1 1 ) : 1 476- 1 479. 1 07. Urtubia RM , Aguila CM, Cumsille MA. Combirube: a study for proper use. Anesth Analg. 2000;90(4) : 9 5 8-962. 1 08 . Walz R, Davis S, Panning B. Is the Combitube a useful emergency airway device for anesthesiologists? Anesth Analg. 1 999;88 ( 1 ) :233. 1 09. Butler BD, Little T, Drtil S. Combined use of the esophageal-tracheal Combitube with a colorimetric carbon dioxide detector for emergency intubation/ventilation. j Clin Manit. 1 99 5 ; 1 1 (5):3 1 1 -3 1 6. 1 1 0. Wafai Y, Salem MR, Baraka A, Joseph NJ, Czinn EA, Paulissian R. Effectiveness of the self-inflating bulb for verification of proper place­ ment of the Esophageal Tracheal Combirube. Anesth Analg. 1 995;80 ( 1 ) : 1 22-1 26. I l l . Bishop MJ, Kharasch ED. Is the Combitube a useful emergency air­ way device for anesthesiologists? Anesth Analg. May 1 998;86(5): 1 1 4 1 - 1 142. 1 1 2. Brimacombe J, Berry A. The oesophageal tracheal combirube for difficult intubation. Can J Anaesth. 1 994;41 (7) :656-657. 1 1 3 . Mercer M. The role of the Combitube in airway management. Anaesthesia. 2000;5 5 (4) :394-39 5 . 1 1 4. Staudinger T, Tesinsky P, Klappacher G, e t al. Emergency intubation with the Combitube in two cases of difficult airway management. Eur J Anaesthesia!. 1 99 5 ; 1 2(2) : 1 89- 1 93 . 1 1 5 . Banyai M, Falger S, Roggla M, e t al. Emergency intubation with the Combirube in a grossly obese patient with bull neck. Resuscitation. 1 993;26(3) :27 1 -276. 1 1 6. Deroy R, Ghoris M. The Combirube elective anesthetic airway manage­ ment in a patient with cervical spine fracture. Anesth Analg. 1 998;87(6) : 1 44 1 - 1 442. 1 1 7. Klauser R, Roggla G, Pidlich J, Leithner C, Frass M. Massive upper air­ way bleeding after thrombolytic therapy: successful airway management with the Combitube. Ann Emerg Med. 1 992;2 1 (4) :43 1 -433. 1 1 8 . Bercker S, Schmidbauer W, Volk T, et al. A comparison of seal in seven supraglottic airway devices using a cadaver model of elevated esophageal pressure. Anesth Analg. 2008; 1 06 (2) :445-448. 1 1 9. Krafft P, Roggla M, Fridrich P, Locker GJ, Frass M, Benumof JL. Bronchoscopy via a redesigned Combitube in the esophageal position. A clinical evaluation. Anesthesiology. 1 997;86(5) : 1 04 1 - 1 04 5 . 1 20. Calkins TR, Miller K , Langdorf MI. Success and complication rates with prehospital placement of an esophageal-tracheal combirube as a rescue airway. Prehosp Disaster Med. 2006; 2 1 (2) :97- 1 00. 1 2 1 . Vezina D, Lessard MR, Bussieres J, Topping C, Trepanier CA. Complications associated with the use of the Esophageal-Tracheal Combitube. Can JAnaesth. 1 998;45 ( 1 ) : 76-80. 1 22. Zamora JE, Saha TK. Combitube rescue for Cesarean delivery fol­ lowed by ninth and twelfth cranial nerve dysfunction. Can J Anaesth. 2008;5 5 ( 1 1 ) :779-784. 123. Bagheri SC, Stockmaster N, Delgado G, et al. Esophageal rupture with the use of the Combitube: report of a case and review of the literature. J Oral Maxillofoc Surg. 2008;66(5 ) : 1 04 1 - 1 044. 1 24. McGlinch BP, Martin DP, Volcheck GW, Carmichael SW. Tongue engorgement with prolonged use of the esophageal-tracheal Combitube. Ann Emerg Med. 2004;44(4) :320-322. 1 25 . Agro F, Cataldo R, Alfano A, Galli B. A new prototype for airway man­ agement in an emergency: the Laryngeal Tube. Resuscitation. 1 999;41 (3): 284-286. 1 26. Asai T, Shingu K. The laryngeal tube. Br j Anaesth. 2005;95 (6) : 729-736. 1 27. Dumbarton TC, Hung OR, Kent B. Overinflation of a King LT Extraglottic Airway Device Mimicking Ludwig's Angina. A & A case reports. 20 1 6;6(4) :80-83.

1 28 . Dorges V, Ocker H, Wenzel V, Schmucker P. T h e laryngeal tube: a new simple airway device. Anesth Ana/g. 2000;90(5): 1 220- 1 222. 1 29. Finteis T, Genzwuerker HV, Hinkelbein J, Roth H, Schmeck J. LMA­ Unique, SoftSeal, LTD and LaryVent: bench model comparison of 4 single-use supraglottic airway devices to facemask ventilation. Respiration. 2004;2 1 :65, (A-262) . 1 30. Wiese CH, Bahr J, Graf BM. "Laryngeal Tube-D" (LT-D) and "Laryngeal Mask" (LMA) . Dtsch Med Wochenschr. 2009; 1 34(3) :69-74. 1 3 1 . Genzwuerker HV, Fritz A, Hinkelbein J, et al. Prospective, randomized comparison of laryngeal tube and laryngeal mask airway in pediatric patients. Paediatr Anaesth. 2006; 1 6 ( 1 2) : 1 25 1 - 1 256. 1 32. Asai T, Murao K, Shingu K. Efficacy of the laryngeal tube during intermittent positive-pressure ventilation. Anaesthesia. 2000;5 5 ( 1 1 ) : 1 099- 1 1 02. 1 33 . Marquez X, Marquez A. A new laryngeal rube. Anesth Analg. 2003; 96(6) : 1 842. 1 34. Asai T, Kawachi S. Pressure exerted by the cuff of the laryngeal tube on the oropharynx. Anaesthesia. 200 1 ; 56(9) : 9 1 1 -9 1 2. 1 3 5 . Agro FE, Galli B, Cataldo R, et al. Relationship between body mass index and ventilation with the Laryngeal Tube(R) in 228 anesthetized paralyzed patients: a pilot study. Can ]Anaesth. 2002;49 (6) : 64 1 -642. 1 36. Bartone L, lngelmo PM, De Ninno G, et al. Randomized controlled trial comparing the laryngeal tube and the laryngeal mask in pediatric patients. Paediatr Anaesth. 2006; 1 6 (3) :25 1 -257. 1 37. Genzwuerker HV, Vollmer T, Ellinger K. Fibreoptic tracheal intuba­ tion after placement of the laryngeal tube. Br j Anaesth. 2002;89(5): 733-73 8. 1 38 . Diirges V, Francksen H, Bein B, Moikow L, Steinfath M. Disposable Laryngeal Tube vs. Laryvent. Anesthesiology. 2004; I 0 I :A568. 1 3 9 . Cook T, Nolan JP, Gupta KJ, Gabbott DA. The Airway Management Device (AMD) is not 'reliable and safe'. Anaesthesia. 2002; 57(3):29 1 . 1 40. Johnson R, Bailie R. Airway management device (AMD) for airway con­ trol in percutaneous dilatational tracheostomy. Anaesthesia. 2000; 5 5 (6) : 596-597. 1 4 1 . Mandai NG. A new device has to be safe and reliable too. Anaesthesia. 200 I ;56(4) :382-3 83. 1 42. Pay LL, Lim Y. Comparison of the modified Airway Management Device with the Proseal laryngeal mask airway in patients undergoing gynaeco­ logical procedures. Eur j Anaesthesia!. 2006;23 ( 1 ) : 7 1 -75. 1 43 . Hooshangi H, Wong DT. Brief review: the Cobra Perilaryngeal Airway (CobraPLA and the Streamlined Liner of Pharyngeal Airway (SLIPA) supraglottic airways. Can J Anaesth. 2008; 5 5 (3) : 1 77- 1 85 . 1 44. Agro F, Barzoi G, Carassiti M, Galli B. Getting the tube i n the oesopha­ gus and oxygen in the trachea: preliminary results with the new supraglot­ tic device (Cobra) in 28 anaesthetised patients. Anaesthesia. 2003 ; 5 8 (9): 920-92 1 . 1 4 5 . Agro F, Carassiti M , Barzoi G , Millozzi F, Galli B . A first report o n the diagnosis and treatment of acute postoperative airway obstruction with the CobraPLA. Can ]Anaesth. 2004;5 1 (6) :640-64 1 . 1 46. Gaitini L , Yanovski B , Somri M , Vaida S , Riad T, Alfery D . A comparison between the PLA Cobra and the Laryngeal Mask Airway Unique during spontaneous ventilation: a randomized prospective study. Anesth Ana/g. 2006; 1 02 (2) : 6 3 1 -636. 1 47. Kusaka Y, Uda R, Son H, Akatsuka M. Successful fi.beroptic tracheal intubation via Cobra PLA in a patient with an epiglottic rumor. Masui. 2009; 5 8 (4):474-476. 1 48 . Andrews DT, Williams DL, Alexander KD, Lie Y. Randomised compari­ son of the Classic Laryngeal Mask Airway with the Cobra Perilaryngeal Airway during anaesthesia in spontaneously breathing adult patients. Anaesth Intensive Care. 2009;37 ( 1 ) : 8 5-92. 1 49. Wronska-Sewruk A, Nestorowicz A, Kowalczyk M. Classic laryngeal mask airway vs COBRA-PLA device for airway maintenance during minor urological procedures. Anestezjol lntens Ter. 2009;41 (2) :73-77. 1 50. Galvin EM, van Doorn M, Blazquez ], et al. A randomized prospective study comparing the Cobra Perilaryngeal Airway and Laryngeal Mask Airway-Classic during controlled ventilation for gynecological laparos­ copy. Anesth Ana/g. 2007; 1 04 ( 1 ) : 1 02- 1 05 . 1 5 1 . Park S H , Han S H , D o S H , Kim J W, Kim J H . The influence of head and neck position on the oropharyngeal leak pressure and cuff posi­ tion of three supraglottic airway devices. Anesth Ana/g. 2009; 1 0 8 ( 1 ) : 1 1 2- 1 1 7. 1 52. Khan RM , Maroof M, Johri A, Ashraf M, Jain D. Cobra PLA can over­ come LMA failure in patients with face and neck contractures. Can j Anaesth. 2005;52(3):340. 1 53 . van Zundert A, Brimacombe J, Kamphuis R, Haanschoten M. The ana­ tomical position of three extraglottic airway devices in patients with clear airways. Anaesthesia. 2006;6 1 (9) : 89 1 -895.

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Ai rway Tec h n i q ues 1 54. Cook T M , Lowe J M . A n evaluation of the Cobra Perilaryngeal Airway: study halted after two cases of pulmonary aspiration. Anaesthesia. 2005;60(8) :79 1 -796. 1 5 5 . Farrow C, Cook T. Pulmonary aspiration through a Cobra PLA. Anaesthesia. 2004;59 ( 1 1 ) : 1 1 40- 1 1 4 1 ; discussion 1 1 4 1 - 1 1 42. 1 56. Miller OM, Lavelle M. A streamlined pharynx airway liner: a pilot study in 22 patients in controlled and spontaneous ventilation. Anesth Analg. 2002;94(3) :759-76 1 . 1 57. Miller OM, Light D . Laboratory and clinical comparisons o f the Streamlined Liner of the Pharynx Airway (SLIPA) with the laryngeal mask airway. Anaesthesia. 2003 ; 5 8 (2): 1 36- 1 42. 1 5 8 . Kang H, Kim DR, Jung YH, et al. Pre-warming the Streamlined Liner of the Pharynx Airway (SLIPA) improves fitting to the laryngeal struc­ ture: a randomized, double-blind study. BMC Anesthesiology. 20 1 5 ; 1 5 : 1 67. 1 5 9. Choi GJ, Kang H, Baek CW, et al. Comparison of streamlined liner of the pharynx airway (SLIPA ) and laryngeal mask airway: a systematic review and meta-analysis. Anaesthesia. 201 5;70(5) : 6 1 3-622. 1 60. Hagberg CA, Jensen FS, Genzwuerker HV, et al. A multicenter study of the Ambu laryngeal mask in nonparalyzed, anesthetized patients. Anesth Analg. 2005; 1 0 1 (6) : 1 862- 1 866. 1 6 1 . Sudhir G, Redfern D, Hall JE, Wilkes AR, Cann C. A comparison of the disposable Ambu AuraOnce Laryngeal Mask with the reusable LMA Classic laryngeal mask airway. Anaesthesia. 2007;62 (7) : 7 1 9-722. 1 62. The Ambu' AuraOnce'M Single Use Laryngeal Mask: Product Information. Ambu: Am bu. 1 63 . Baidya OK, Chandralekha, Darlong V, Pandey R, Maitra S, Khanna P. Comparative efficacy and safety of the Ambu((R) ) AuraOnce() laryngeal mask airway during general anaesthesia in adults: a systematic review and meta-analysis. Anaesthesia. 20 1 4;69 (9) : 1 023- 1 032. 1 64. Intersurgical. i-gel User Guide. 2009. http://www.i-gel.com/lib/docs/ instructions/i-gelo/o20usero/o20guide_UK.pdf. Accessed January 5 , 20 1 6 . 1 65 . Gabbott DA, Beringer R . Th e iGEL supraglottic airway: a potential role for resuscitation? Resuscitation. 2007;73 ( 1 ) : 1 6 1 - 1 62. 1 66. Liew G, John B, Ahmed S. Aspiration recognition with an i-gel airway. Anaesthesia. 2008;63 (7) :786. 1 67. Gibbison B, Cook TM, Seller C. Case series: Protection from aspira­ tion and failure of protection from aspiration with the i-gel airway. Br j Anaesth. 2008; 1 00(3) : 4 1 5-4 1 7. 1 68 . Gatward JJ, Cook TM, Seller C, et al. Evaluation of the size 4 i-gel air­ way in one hundred non-paralysed patients. Anaesthesia. 2008;63 ( 1 0) : 1 1 24- 1 1 30. 1 69. Schmidbauer W, Bercker S, Volk T, Bogusch G, Mager G, Kerner T. Oesophageal seal of the novel supralaryngeal airway device !-Gel in comparison with the laryngeal mask airways Classic and ProSeal using a cadaver model. Br j Anaesth. 2009; 1 02 ( 1 ) : 1 3 5 - 1 3 9 . 1 70. Jackson KM, Cook T M . Evaluation of four airway training manikins as patient simulators for the insertion of eight types of supraglottic airway devices. Anaesthesia. 2007;62 (4) :388-393. 1 7 1 . Richez B, Salce! L, Banchereau F, Torrielli R, Cros AM. A new single use supraglottic airway device with a noninflatable cuff and an esopha­ geal vent: an observational study of the i-gel. Anesth Analg. 2008; 1 06( 4): 1 1 37- 1 1 39. 1 72. Michalek P, Hodgkinson P, Donaldson W. Fiberoptic intubation through an I-gel supraglottic airway in two patients with predicted difficult airway and intellectual disability. Anesth Analg. 2008; 1 06(5): 1 50 1 - 1 504. 1 73 . Joshi NA, Baird M, Cook TM. Use of an i-gel for airway rescue. Anaesthesia. 2008;63 (9): 1 020- 1 02 1 . 1 74. Sharma S , Scott S , Rogers R, Popat M. Th e i-gel airway for ventilation and rescue intubation. Anaesthesia. 2007;62 (4) : 4 1 9-420. 1 75 . Lockey D, Crewdson K, Weaver A, Davies G. Observational study of the success rates of intubation and failed intubation airway rescue techniques in 7256 attempted incubations of trauma patients by pre-hospital physi­ cians. Br} Anaesth. 20 1 4; 1 1 3 (2):220-225.

SELF-EVALUATION QU ESTIONS 1 3 . 1 . Which of the following i s NOT true about the Laryngeal Tube (King LT) ? A. I t cannot b e used i n patients with a history o f latex allergy. B . The Laryngeal Tube has rwo cuffs (pharyngeal and esophageal) but a single balloon for pressure control. C. The Laryngeal Tube requires a mouth opening of at least 23 mm for its insertion. D. The Laryngeal Tube cuffs should be inflated to a pres­ sure up to 60 em H 0 using a manometer if possible. 2 E. A well-lubricated endotracheal rube can be passed blindly through the airway lumen of the LT. 1 3 .2. Which of the following is NOT true with the use of the Laryngeal Mask Airway? A. In general, approximately 20 mL is required to inflate the cuff for a #3, 30 mL for a #4, and 40 mL for a #5 LMA. B. The LMA should be inserted into the mouth with the index finger placed berween the mask-rube junction. C. The LMA cuff should be pressed against the hard pal­ ate during the insertion into the oropharynx. D. Prior to insertion, the cuff should be completely deflated. E. To facilitate placement, the LMA should be lubri­ cated using lidocaine gel. 1 3 . 3 . In comparison with tracheal intubation, which of the following is NOT an advantage of the LMA? A. Improved hemodynamic stability on induction and during emergence B. No risk of gastric aspiration C. Reduced anesthetic requirements for airway tolerance D. Lower frequency of coughing during emergence E. A lower incidence of sore throat in adults

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C H A PT E R 1 4

Cricothyrotomy Gordon 0. Launcelott, Liane B. Johnson, David T. Wong, and Orlando R. Hung

I NTRO D U CTION .

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TECH N I Q U E S

262

OTH ER CO N S I D E RATIO N S . . . . . . . . . . . . . . . . . . . . . . . . 267 COM P LICATI ONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

267

S U M MARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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SELF-EVALUATIO N Q U ESTI O N S . . . . . . . . . . . . . . . . . . . 269

I NTRODUCTION In 1 799, as George Washington lay dying of life threat­ ening upper airway obstruction, one of his physicians, Elisha Cullen Dick, argued against further bloodletting and for tracheotomy. In retrospect this was the only life­ saving option available. It was not attempted and the President succumbed. 1 Indications for surgical airway access vary from the elective through to impending airway compromise, and finally to the true emergency "cannot intubate, cannot oxygenate" scenario. This chapter will deal primarily with techniques of surgical airway (cricothyrotomy) access that the practitioner can use to deal with the difficult airway that presents either in the form of impending airway compromise or the life-threatening emergency. • Why Cricothyrotomy and

Not Tracheotomy?

The higher complication rate of emergency tracheotomy, com­ pared to cricothyrotomy, 2 results from the fact that the trachea

is situated deeper in the neck, the posterior tracheal wall lacks the protection of a circumferential cricoid cartilage (increasing the risk of esophageal perforation) , there is a greater abundance of adjacent vascular structures, and there is a proximity of the thyroid gland and lung apices. The palpable, often visible, sur­ face landmarks of the thyroid and cricoid cartilages and the abiliry to accomplish the task faster, with a minimum of equip­ ment, making emergency cricothyrotomy more attractive than tracheotomy, for the surgeon and non-surgeon alike.3 As a consequence, all of the techniques to be discussed with the exception of open and percutaneous dilational tracheotomy (see Chapters 1 5 and 33) and possibly needle insufflation in children will involve access to the airway through the cricothy­ roid membrane (CTM) . • What Is the History of Cricothyrotomy?

Surgical access to the airway has its origins in ancient times but it was the pandemic of "morbus strangulatorius" in Europe at the beginning of the 1 9th century that began its modern evo­ lution. The French surgeon, Pierre Bretonneau, first attempted to relieve the laryngeal obstruction of this infectious laryngo­ tracheal-bronchitis by tracheotomy in 1 8 1 8 , finally meeting with success in 1 82 5 .4 His paper, published in 1 826, gave the disease entity the name diphtheria,5 from the Greek "diphthera" meaning leather. This was in recognition of the thick, leathery, blue white upper respiratory tract membranes characteristic of the disease.6 In the 20 years that followed, Armand Trousseau, Joseph Recamier, and M. P. Guersant honed the technical aspects of "bronchotomy"7-laryngotomy and tracheotomy­ and by 1 8 5 1 Trousseau published his experience in 222 cases, 1 27 of whom survived.8 In the United States, Chevalier Jackson9 published further refine­ ments to the technique in 1 909. More than a decade later ( 1 921), he published a paper auributing the devastating complication of subglottic stenosis (SGS) to "high'' tracheotomy, concluding that the only acceptable point of access to the airway was below the first

260

Ai rway Tec h n i q ues

tracheal ring and that "high" tracheotomy should be abandoned.10 Jackson was a figure of immense authority1 1 and it is not surprising that "high" tracheotomy, or cricothyrotomy, was relegated to almost total obscurity for close to five decades. Brantigan and Gro� renewed interest in the approach fol­ lowing publication of their 1 976 paper. The impetus for the study came from anecdotal experience during the early days of cardiac surgery. Grow, a student of Chevalier Jackson, looked to cricothyrotomy as a way to avoid contamination of median sternotomy wounds by pathogens tracking down the shared mediastinal tissue planes from open tracheotomy sites. He began performing cricothyrotomy, initially in emergency situa­ tions, and later electively when it was evident to him that SGS did not appear to be a problem. Grow and Brantigan reported their experience in 655 cri­ cothyrotomies performed over an 8-year period. Duration of intubation ranged from 1 to less than 40 days, with an aver­ age of 7 days. Their results showed minimal complications and no cases of SGS. Subsequently, several authors, 1 2- 14 including a recent prospective study, 15 reported similar findings in patients not previously subjected to prolonged endotracheal intubation, or suffering from any acute laryngeal pathology. The discrepancy between the observations of Jackson in the 1 920s and the modern authors results from several fac­ tors that reflect the two eras, separated by over half a century. Most of the indications for a surgical airway in Jackson's era were inflammatory in nature; cricothyrotomy in the presence of inflammation is now well recognized to predispose to SGS. In addition, "high" tracheotomy was a much more complex procedure than the modern cricothyrotomy, involving division of the cricoid or thyroid cartilages. The lack of antibiotics, and the primitive design of the tracheostomy tubes available in the 1 920s, undoubtedly compounded the situation. 16 As cricothyrotomy is more advantageous for its speed, safety, and simplicity, 17 access through the CTM is the technique of choice in emergency surgical airway management. Talving et al.18 reviewed 30 years of literature to determine the rate of development of SGS following emergency cricothyrotomy, with a subset analysis of trauma patients, making up approxi­ mately one-third of the total number. The overall rate of SGS was identified in 2.2% of survivors and 1 . 1 % of trauma patients. Interestingly, the rate of development of SGS in the emergency airway is comparable to the rate of SGS from endotracheal intu­ bation, ranging from 0.9% to 8.3% in the literature. Although a well-designed randomized, prospective study is warranted, it currently appears that in the absence of an inflammatory cause of airway obstruction, the development of SGS by emergency cri­ cothyrotomy poses little change in risk to that of routine, daily endotracheal intubation. Although there is increasing evidence to support a change in current practice, most practitioners would prefer to convert a cricothyrotomy to a tracheotomy within 24 hours to avoid the devastating complication of SGS. • What Anatomy Do I Have to Know to

Perform These Procedu res?

Access to the airway through the CTM requires a practi­ cal knowledge of the anatomy of the larynx, particularly the

F I G U R E 1 4- 1 . Anatomy of the la rynx a n d trachea: (A) the thyroid ca rti l a g e; (B) the cricothyroid m e m bra n e; a n d (C) the cricoid ca rti l a g e.

surface landmarks, as well as the important adjacent structures in the neck. In most adult males, the thyroid notch ("Adam's apple") is a prominent feature, which identifies the superior aspect of the thyroid cartilage. With the neck extended, palpation inferiorly from this point will often allow the practitioner to identify the inferior margin of the thyroid cartilage and the ringed shaped cricoid cartilage below (Figure 14-1) . Between the inferior mar­ gin of the thyroid and cricoid cartilages is the CTM. The size of the membrane in adults is 22 to 33 mm wide and 9 to 1 0 mm high.19 Should landmarks be difficult to palpate, the level of the CTM can be estimated by the finger stacking technique (or four-finger technique) 20: with the head and neck in neutral position, the fifth finger is placed in the suprasternal notch; with all fingers in j uxtaposition, the location of the index fin­ ger will approximate the level of the CTM. In addition, skin creases ("Launcelott creases") in the anterior neck may repre­ sent a useful visual landmark for estimating the level of the CTM. The study conducted at our institution demonstrated that with the head in the neutral position, in patients with two neck creases inferior to the mentum, the second skin crease was about 2.0 mm (median distance) above the cricoid cartilage (Figure 14-2) . 2 1 The vocal cords are attached to the internal, anterior sur­ face of the thyroid cartilage approximately 1 em above its infe­ rior border. 22 Care should be exercised in placing retraction instruments superior to the cricothyroid incision to minimize trauma to the vocal cords and body of the thyroid cartilage in

Cri cothyroto my

• How Can I Predict Whether Access Th rough

the CTM Will be Difficult?

Although there is no formal evidence, it is intuitive that any­ thing interfering with either physical access to the larynx, or the abiliry to appreciate the landmarks of the larynx, will make CTM puncture difficult. This includes factors such as previous surgery, fixed cervical spine flexion deformiry, hema­ toma, obesiry, radiation to the neck, laryngotracheal malig­ nancy, or tumor. SHORT (Surgery/Spine, Hematoma, Obesiry, Radiation, and Tumor) is a useful mnemonic to remind practi­ tioners of the factors that may be associated with a difficult sur­ gical airway (see section "Difficult Cricothyrotomy: SHORT" in Chapter 1 ) . Pediatric patients also pose great difficulty as the laryngeal structures and spaces are small and difficult to palpate and won't mature until approximately 1 2 years of age. • Can the CTM Anatomical Landmark

be Better Defined?

F I G U R E 1 4-2. S u rfa ce l a n d m a rks of the a nterior n eck: thyroid ca r­ t i l a g e (TC), fi rst s k i n crease below mentu m (C l ), second s k i n crease below m e n t u m (C2), and cricoid ca rti la g e (CC).

the anterior midline. The only vascular structure of note in the viciniry of the CTM is the superior thyroid artery, which, in 54% of people, courses along its lateral border. 23 The left and right cricothyroid arteries, branches of their respective superior thyroid arteries, course medially and traverse the upper half of the CTM, 2 3 anastomosing in the midline. Injury to these ves­ sels can be avoided by entering the CTM in its inferior half. Other important anatomical structures include the hyoid bone and the thyroid gland with its central isthmus and pos­ sible presence of an attached pyramidal lobe. The airway itself is suspended by the hyoid bone lying superior to the thyroid car­ tilage. Identifying the hyoid bone is important to avoid mistak­ ing the thyrohyoid space for the CTM. In patients with poorly palpable surface anatomy, the location of the hyoid bone can be estimated by extending a line from the mentum posteriorly, half the distance berween the mentum and the angle of the mandible, 24 and distinguishing this underlying structure from the lower lying thyroid and cricoid cartilages. Identifying all the laryngeal structures, whether from top down or down up, is crucial prior to making a surgical incision. The thyroid gland has a pyramidal lobe in up to 40% of patients. 2 5 The pyramidal lobe is highly vascular and has a propensiry to come off the left side of the thyroid isthmus. Extension superiorly beyond the thyroid cartilage is often notable as a fibrous band which is a remnant of the thyroglos­ sal duct. Extension beyond the thyroid cartilage as high as the hyoid bone is very rare26•27 and poses a small additional bleed­ ing risk due to injury during cricothyrotomy.

Ultrasound-guided identification of the CTM should not be used in a "can't intubate, can't oxygenate" emergency situation. However, it can be very useful in accurately identify CTM puncture site prior to induction of an elective or semi-elective patient suspected of having a difficult airway. In a recent review article, Kristensen2 8 showed that the CTM can be accurately, reliably, and expeditiously identified by bedside ultrasound (Figure 14-3) . Studies have shown that practitioners accurately identified the CTM puncture site by palpation in only 1 0o/o to 30o/o of attempts. 2 9 The accuracy in CTM identification was even lower in obese individuals, especially notable in the obese female.30' 31 Prasad et al.3 2 showed that there is good cor­ relation in identification of airway structures and dimension measurements berween ultrasound and CT modalities. Thus in semi-elective cases with suspected or known difficult airway, especially in subjects with difficult CTM identification by pal­ pation, a rapid bedside ultrasound marking of CTM can be quite useful and potentially life-saving. • What Do I Need to Do to Get Ready?

The following are common to all techniques of surgical access by way of the CTM. a. Antisepsis and local anesthetic infiltration: If time permits, every effort should be made to use aseptic technique and infiltrate the proposed surgical site with local anesthetic. b. Positioning the patient: The patient is ideally placed in the supine sniffing posi­ tion, ensuring sufficient ramping of the patient so that their earlobes are at or above the level of the sternum, and then extending the head to best expose the surface landmarks of the larynx. In an emergency situation, particularly in the set­ ting of severe upper airway obstruction, it may be necessary to position the patient semi-recumbent, or fully erect. c. Immobilization ofthe larynx and identification ofthe C1M: Immobilization of the larynx and identification of the CTM is most effectively accomplished by the right-handed

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F I G U R E 1 4-3. U ltraso u n d - g u ided ide ntification of the cricothyroid m e m bra ne (CTM) . Top Left An I ma g e obta i ned with high freq uency u ltraso u n d probe i n l o n g itud i n a l axis i n the m i d l i ne. Top R i g h t 3 red a r rows m ov i n g l eft to right poi nti n g to (green l i ned, fi rst red a rrow) = thyro i d ca rti l a g e; (cri mson ba r) = CTM, (ob l o n g d a r k bl ue solid, secon d red a rrow) = cricoid ca rti l a g e, (str i n g of l ig h t b l u e structu res, t h i rd a r row) = fi rst to t h i rd tra c h e a l r i n g s. Bottom . Yel l ow a rrow, hypoec hoic structu re = t h roid carti l a g e, Wh ite a rrow, t h i n hyperec hoic l i ne = CTM, Fi rst b l u e a rrow, hypoechoic structu re = Cricoid ca rti l a g e, second b l ue a r row, stri n g of 6 hypoec hoic struct u re = trac hea l r i n g s . .

techniques, immobilizing the larynx and identifying the CTM with the left hand from below. This permits the practitioner to use the right hand to pass implements through the CTM in a caudad direction and in a more dextrous fashion. Primary immobilization of the larynx by the left hand, from below, also minimizes trauma to the thyroid cartilage by promoting retraction of the cricoid ring inferiorly, rather than superior retraction on the thyroid cartilage.

TECH N I Q U ES

F I G U R E 1 4-4. Pa l patio n of the cricothyroto my m e m bra n e i n a cad aver: The l eft (nondom i n a nt) h a n d is used to sta b i l ize the l a rynx by g r a s p i n g the body of the thyroid carti la g e between t h e th u m b a n d m i d d l e fi nger l eavi n g t h e i n d ex fi n g e r free t o pa l pate t h e ca rti­ l a g i n o u s struct u res.

practitioner standing on the right side of the patient. The left (nondominant) hand is used to stabilize the larynx by grasp­ ing the body of the thyroid cartilage between the thumb and middle finger leaving the index finger free to palpate the cartilaginous structures (Figure 14-4) . If the thyroid notch is palpable, the index finger is moved cau­ dad along the thyroid cartilage, in the midline, until the fingertip dips off its inferior aspect onto the CTM, bounded by the cricoid arch inferiorly. If the landmarks are not palpable, then identifi­ cation of surface landmarks ("Launcelott creases"), suprasternal finger stacking, or ultrasound-guidance can be used to rapidly guide the airway practitioner to the CTM, as described above. For transtracheal catheter and Seldinger techniques, some right-handed practitioners will choose to stand over the right shoulder or at the head of the patient, immobilizing the larynx and identifying the CTM, as described above. Others will choose to stand on the left side of the patient for these

Four methods of surgical access to the airway through the CTM are outlined: 1. 2. 3. 4.

Open cricothyrotomy Seldinger cricothyrotomy Scalpel bougie cricothyrotomy Transtracheal catheter ventilation

• Can You Wa lk Me Through Each

Method . . . Step by Step?

1. Open cricothyrotomy Equipment: The instruments required are: a scalpel with a # 1 1 blade; a tracheal hook; Armand Trousseau dilator; and a 5 .0-mm ID cuffed endotracheal tube (ETT) , or a small, cuffed tra­ cheotomy tube (Figure 14-5) . Technique: It should be clearly appreciated by the practitioner that the technique of emergency cricothyrotomy is a sensori­ ally rich procedure. Primarily a tactile technique rather than a visual one, when entering the CTM space an audi­ tory exhaled "woosh" of air, blood, and possibly pulmonary edema will be seen and heard. Landmarks must be palpated

Cri cothyroto my

F I G U R E 1 4-7. Open cricothyroto my in a cadaver: retraction with a trac hea l hook s u periorly. F I G U R E 1 4-5. Eq u i pment req u i red for a n open cricothyrotomy: a sca l pe l with a # 1 1 b l a d e; a tracheal h ook; A r m a n d Tro u ssea u d i l ator; a n d a s m a l l , cuffed tra c h ea l tube (o r a cuffed tra c heotomy tu be) .

F I G U R E 1 4-8. Open cricothyrotomy i n a cadaver: i n sertion of the Trousseau d i l ator. F I G U R E 1 4-6. Open cricothyrotomy i n a cad aver: A 4 em vertica l, m i d l i n e s k i n i nc i s i o n is ma d e fo l l owed by a tra n sverse i ncision of the CTM at the s u perior border of the cricoid ca rti lage.

from the moment the skin incision is made, as you can no longer rely on your eyes alone once the blood covers the sur­ gical site. Thus mental imagery is a useful skill and should be practiced to promote a positive outcome. With the patient positioned and landmarks identified, the following are steps to a successful standard surgical cricothyrotomy technique: 1 . A 4.0 em vertical, midline skin incision (Figure 14-6) ; 2. A transverse incision of the CTM at the superior border of the cricoid cartilage; 3. Retraction with a tracheal hook (Figure 14-7) . Either superiorly, with potential trauma to the vocal cords or thyroid cartilage, or inferiorly, with less risk and perhaps better exposure due to a higher degree of mobility of the cricoid than the thyroid cartilage; 4. Insertion of the Trousseau dilator (Figure 14-8) ; 5 . Caudal placement o f a 5 . 0-mm I D cuffed ETT, o r a small, cuffed tracheotomy tube (Figure 14-9) ; 6. Inflation o f the cuff, ensuring the proper position and removal of the hook and dilator. Prior to securing the tube, it is important to confirm proper placement by ETC02 and/or by auscultation. A Chest X-ray should be obtained, as soon as conveniently possible, to deter­ mine proper tube position and to rule out any parenchymal

F I G U R E 1 4-9. Open cricothyrotomy i n a cadaver: the tracheos­ tomy tu be i s i n serted i nto the trachea t h ro u g h the Trou ssea u d i lator.

lung injury or pneumothorax. Current recommendations view a cricothyrotomy as a temporizing, life-saving measure. The patient should undergo conversion to a traditional tracheotomy once stabilized. 2. Seldinger cricothyrotomy technique Most practitioners are familiar with the Seldinger technique and most will be more comfortable with this approach. The NAP433·34 study revealed that although this is the preferred method by practitioners, the ability to correctly identify the CTM in an emergency "CICO" situation was in the realm of 30% and the technique was fraught with a mul­ titude of issues, such as prolonged procedural time, kinking

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of the guidewire, creation of a false passage, and inability to adequately dilate and cannulate the airway. Equipment: There are several cricothyrotomy kits designed with this technique in mind and all with similar contents. They con­ tain a scalpel blade, a syringe, an I S-gauge catheter over needle, and/or a thin-walled introducer needle, a guidewire, a dilator, and a cuffed airway catheter (Figure 14- 1 0) . Technique: As access to the airway is achieved through the CTM, the anatomic considerations and patient positioning are the same as for open cricothyrotomy. The technique is summa­ rized as follows:

5 . After making a small cut of the CTM along the guidewire (Figure 14- 1 3) , the cuffed airway catheter loaded onto the dilator is advanced as a single unit, over the wire and into the airway (Figure 14- I4) . 6 . Removal o f dilator and guidewire prior to securement of the tube. 7. Confirmation of proper tube placement by ETC0 and/ 2 or by auscultation. It should be noted that the Cook Critical Care "Melker" Cricothyrotomy kit contains equipment to perform both open

I . Vertical midline stab incision through the skin overlying the CTM; 2. Caudal insertion of an I S-gauge needle attached to a syringe (Figure 14- 1 1) ; 3 . Confirmation o f needle placement by aspirating air, fol­ lowed by removal of the needle and syringe; 4. Insertion of the guidewire (Figure 14- 12) and removal of the catheter, leaving the guidewire in the trachea; F I G U R E 1 4- 1 2. Seld i n g e r cricothyrotomy in a cadaver: after con­ fi r m i ng acc u rate need l e placement by a s p i rati n g a i r, the need l e a n d syri n g e a re removed. A g u idewi re i s i n serted i nto the trachea t h ro u g h the catheter.

F I G U R E 1 4- 1 0. Eq u i pment for S e l d i n g e r cricothyrotomy: a sca l pel b l a d e, a syr i nge, a n 1 8- g a u g e catheter ove r need l e a n d/or a t h i n­ wa l l ed i ntrod ucer need le, a g u idewire, a d i l ator, a n d a cuffed a i rway cath ete r.

F I G U R E 1 4- 1 1 . S e l d i nger cricothyrotomy i n a cadaver: Fol l owing a vertical m i d l i n e sta b i ncision t h ro u g h the s k i n overlying the CTM, a n 1 8-gauge need le attached t o a syri nge i s i n serted t h ro u g h t h e CTM.

F I G U R E 1 4- 1 3. Seld i n g e r cricothyrotomy i n a cadaver: a s m a l l c u t o f t h e CTM i s m a d e a l o n g t h e g u id ew i re.

F I G U R E 1 4- 1 4. The a i rway catheter loaded onto the d i l ator i s adva n ced a s a s i n g l e u n it t h ro u g h the g u id ew i re.

Cri cothyroto my

and Seldinger techniques. Once again, current teaching recom­ mends conversion to a formal tracheotomy, once the patient is stabilized. 3. Scalpel bougie cricothyrotomy This is a rapid technique requiring very little equipment compared to the open surgical method. The main pitfall of the open surgical technique for an anesthesia practitioner is that most practitioners are unfamiliar with open scalpel cuts which might lead to hesitation and delay in execut­ ing an emergency cricothyrotomy.35 The use of a bougie (Eschmann Tracheal Introducer or commonly known as "gum elastic bougie") as an intermediary to insertion of an ETT is a familiar technique to most practitioners. With this technique, after a scalpel puncture of the CTM, a bougie is inserted, followed by advancing of an ETT over the bougie. 36 Equipment: Size 20 scalpel on a handle, tracheal tube introducer (bougie) , 5 . 5-mm ID cuffed ETT (size 5 . 0-mm ID or smaller ETT would not work with the bougie because intro­ ducers typically have a size 4.7-mm OD and the Gum elastic bougie has a size 5 . 0-mm OD) .

F I G U R E 1 4- 1 6. Sta b i n c i s i o n i s m a d e with sca l pel oriented h o ri­ zonta l ly t h ro u g h cricothyroid m e m bra n e (CTM) u s i n g d o m i n a nt h a n d in a cadaver. The m o n itor d is p l a y fro m the fl ex i b l e bro n cho­ scope s h ows the sca l pel blade (S) i n side the tra c h ea fo l l ow i n g the cut t h ro u g h the CTM.

Technique: 1 . IdentifY CTM with nondominant (ND) hand (Figure 14-15); 2 . Make stab incision with scalpel oriented horizontally through CTM using dominant hand (Figure 14- 1 6) ; 3 . Rotate blade 9 0 degrees into a vertical orientation (Figure 14- 1 7) and pull scalpel blade toward the practitioner pro­ ducing a triangular wedged shape hole; 4. With bougie tail pointing away from the practitioner and using the ND hand, insert the coude tip of the bou­ gie through the triangular wedged hole into the trachea so that the long axis of the bougie is almost horizontal to long axis of the patient using the blade as a guide (Figure 14- 1 8) ;

F I G U RE 1 4- 1 5 . Identify cricothyroid m e m bra n e of t h e cadaver with the n o n d o m i n a n t h a n d . A fl ex i b l e b ro n c h oscope i s p l a ced t h ro u g h the nostri l with the t i p s h owi n g the i nfra g l ottic struct u re of the trachea.

F I G U RE 1 4- 1 7. Rotate b l a d e 90 degrees i nto a vertica l orie ntation a n d pull sca l pel b l a d e towa rd the a i rway practitioner prod u c i n g a tria n g u l a r wedged hole.

F I G U R E 1 4- 1 8. With bou g i e ta i l pointi n g away fro m the prac­ titioner, i n sert the coude tip of the bougie at an a n g l e a l m ost ho rizonta l to l o n g axis of the patient u s i n g the n o n do m i n a nt h a n d t h rou g h the tria n g u l a r wedg e h o l e i nto the trachea u s i n g t h e b l a d e a s a g u ide. T h e m o n itor d i splay fro m the flexi b l e b ro n c h o­ scope s h ows the sca l pel b l a d e (S) with the "bougie" (B) i n side the trachea.

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Options that are available for delivery of 0 2 include jet ven­ tilation, the 0 2 flush valve on the anesthetic machine, and the anesthesia circuit itself. As mentioned above, it is essential that there is sufficient time and an available route for egress of gas. An assistant should be instructed to manage the upper airway with all necessary maneuvers, including LMA, or other airway, and appropriate airway maneuvers. Gaufberg and Workman37 recommend that ventilation with this technique should not exceed 20 minutes in adults and 40 minutes in children. It is also the only recommended emergency surgical airway, other than tracheotomy, in children under the age of 1 2 years. F I G U R E 1 4- 1 9. Adva nce the l u bricated 5.5-m m I D tra c h e a l tube ove r bougie i nto the trachea.

5 . Remove the scalpel blade and advance the bougie into trachea to approximately 1 0 to 1 5 em; 6. Advance the lubricated 5. 5-mm ID tracheal tube over bou­ gie into trachea (Figure 14-19) and then remove the bougie; 7. Confirm correct tracheal placement by end-tidal capnogra­ phy, auscultate, or verifY with bronchoscope if necessary. It should be emphasized that while performing this tech­ nique, the practitioner should be cautious not to advance the tip of the scalpel blade too deep into the trachea following the cut of the CTM. In a cadaver model and with a flexible bronchoscope placed through the nostril and the tip showing the infraglottic structure of the trachea, we had demonstrated that the tip of the scalpel blade repeatedly reached beyond the posterior tracheal wall (see Figure 1 4- 1 6) , suggesting potential tracheal and esophageal inj uries if the scalpel blade advances too deep into the trachea during the procedure. In addition, the disadvantage of this technique is apparent in the patient with a neck where the surface anatomy is not easily discernable and the larynx itself is submerged. Under these circumstances, the clinician may be better served by using a vertical incision, to better locate the CTM by direct palpation, and once punc­ ture of the CTM has occurred, advancement of the bougie and subsequently the ETT would be easier.

a. Transtracheal jet ventilation For the purposes of simplicity only classic transtracheal jet ventilation (TTJV) and TTJV with the ENK modulator will be considered here. Many operating rooms have access to a commercially available jet ventilator, consisting of a high-pressure connec­ tor, high-pressure hosing, an in-line regulator, a jet ventila­ tion toggle switch, and a Luer Lock connector. This device is powered by central wall oxygen at 50 psi ( 1 5 Lmin- 1) and subject to an in-line regulator. Activation of the toggle switch, in a controlled fashion, allows oxygen to be safely jetted through the transtracheal catheter into the airway. An 02 tank regulator powers another form of TTJV system, with similar high-pressure hosing, jet injector, and Luer Lock connector. A low flow tank regulator, as on the E cylinder 0 2 transport tanks, can achieve a maximum pres­ sure of 1 2 0 psi with the flow meter set at 1 5 L min - 1 • When the jet is activated briefly, very high flows are generated and can result in satisfactory tidal volumes through 1 4-gauge catheters over 0 . 5 seconds.38 For all systems, chest rise and fall, and the pulse oximeter response, are noted as a measure of ventilatory adequacy. b. ENK Flow Modulator The ENK Flow Modulator (Figure 14-20) permits trans­ tracheal ventilation by tubing connected to the 0 2 flush

4. Transtracheal catheter ventilation The passage of a 1 2- to 1 4-gauge catheter through the CTM for the purposes of establishing an emergency airway is only a temporizing method at best. It provides short-term oxygenation until a definitive airway can be established. Many variations on this technique have been used in general relation to availability of equipment. This technique should only be used with partial upper airway obstruction as a means of providing oxygenation until a definitive airway can be established in a "CICO" situa­ tion. One such technique is summarized as follows: 1 . Caudal insertion of 1 4 gauge IV catheter, with a fluid-filled syringe attached, through the CTM; 2. Confirmation of position by aspiration air bubbles, and advancement of the catheter to its hub, while removing the needle and syringe; 3. Oxygenation utilizing one of several options; 4. To prevent air trapping, barotrauma, and pneumothorax/ pneumomediastinum, it is critical that there is sufficient time for egress of gas following each ventilation.

F I G U R E 1 4-20. The E N K F l ow M od u l ator: the d evice is eq u i p ped with a series of five holes (a rrows) that ca n be occ l u d ed in a mea­ s u red fa s h i o n to d i rect fl ow t h ro u g h the device to the patient.

Cri cothyroto my

valve on an anesthesia machine, or on a wall-mounted flow meter. The device is equipped with a series of five holes that can be occluded in a measured fashion to direct flow through the device to the patient. As with TTJV, chest rise and fall is noted as a measure of ventilatory adequacy. The CTM catheter/oxygenation technique has limita­ tions discussed above and is not a good choice for definitive airway. However it is invaluable as an initial measure to permit rapid infraglottic access, oxygenation, and stabiliza­ tion. Fourteen-gauge intravenous catheters are readily avail­ able and anesthesia practitioners surveyed showed that they prefer and are more comfortable using intravenous cath­ eter (or Seldinger) than open surgical technique.35 Once oxygenation is provided by j et ventilation or insuffiation through the catheter and the patient stabilized, large-bore catheter access can be gained using a Seldinger kit. Simply insert a guidewire through the existing intravenous catheter into the trachea, make a stab skin incision, then insert a 5 .0- or 6.0-mm ID tube with an embedded dilator into the trachea.

OTH E R CO N S I D E RATIONS • Are There Any Contra indications to Perform

a Cricothyrotomy?

In the emergency situation when gas exchange cannot be estab­ lished, a surgical airway is mandatory to prevent catastrophe. As such, there are no contraindications to a surgical airway. There are, however, certain issues that deserve consideration. In acute or chronic inflammatory laryngeal pathology, and neoplastic disease, cricothyrotomy will likely be more diffi­ cult to perform and be subject to a greater incidence of SGS. Obesity, injuries, and deformities of the neck may either distort the anatomy and/or render surface landmarks difficult to pal­ pate; and uncontrolled hemorrhage may complicate the situ­ ation in the anticoagulated patient. Cricotracheal separation is an absolute contraindication to any procedures that utilize the CTM. • What Are the Concerns in Establishing a

Cricothyrotomy in Patients with a Deep Neck I nfection?

Deep space neck infections are most common in the extremes of age. Underlying medical problems often accompany the affiicted elderly patient. Deep space infections can either vari­ ably occlude, or shift the airway, rendering what should be an easily managed airway into an emergency. Caution dictates that airway management should be performed in a controlled envi­ ronment, preferably the operating room. A CT scan, if feasible, would greatly facilitate understanding of the altered anatomy but this may not be feasible in the severely compromised airway. In the moderately affected airway, topical anesthesia and "awake" intubation using a flexible bronchoscope is the method of choice. If the airway is severely compromised, with total air­ way obstruction a possibility, an "awake" tracheotomy is the procedure of choice-to ensure a secure airway until the infec­ tion and its source can be treated.

• Do You Have Any Concerns in Establishing

a Cricothyrotomy in Children?

In children, as the laryngeal prominence does not develop until adolescence, surface landmarks are more difficult to palpate. The vertical dimension of the CTM is considerably smaller in children than adults, with the result that an ETT may per­ manently damage the cartilaginous structures. There is an increased risk that the cricoid cartilage, the only completely circumferential supporting laryngeal structure may be dam­ aged. In addition, the airway of the child is more malleable, making posterior perforation a greater risk and the laryngeal mucosa more vulnerable to injury and SGS. 16 For all of these reasons, in an emergency situation, if transglottic tracheal tube placement cannot be accomplished, needle cricothyrotomy, or tracheotomy, is the method of choice in children 12 years of age or younger.39 • What Are the Pros and Cons of Using

Non-Cuffed and Cuffed Tracheal Tube for Cricothyrotomy?

The greatest risk of prolonged cricothyrotomy intubation is the development of SGS. Underlying medical illness and/or an ele­ ment of gastro-esophageal reflux, in conjunction with the mechan­ ical disruption of intubation, may contribute to the development of SGS. Modern tracheostomy tubes are less likely to produce an inflammatory response in the mucosal airway, while low-pressure cuffs reduce mechanical trauma and its sequelae. Cuffed tubes provide a seal in the airway to allow delivery of larger tidal volumes with lower airway pressures. However, cuffed tubes may be more difficult to insert in an emergency situation, due to their bulk and the risk of snagging the cuff on the edge of the surgical incision. This may tear the cuff and prevent an effec­ tive seal. It is critical that the simplest, safest, speediest, and most effective technique be used to reestablish a failed airway. Thus a small, non-cuffed tube would be adequate for the primary goal of salvaging the airway and provision of oxygenation. As patients requiring a surgical airway may have decreased lung compliance, positive pressure ventilation through a non­ cuffed ETT can result in gas escaping from the proximal airway, resulting in inadequate ventilation. For this reason either the Cook cuffed airway catheter or 5 . 0-mm ID cuffed ETT are the tracheal tubes of choice when establishing an emergency surgical airway.

COM P LICATIONS • What I m mediate and Delayed

Compl ications Should I be Aware of?

In most studies, complication rates are higher for emergency than elective cricothyrotomy. In a series of 38 emergency cri­ cothyrotomies, McGill et al. 24 reported an overall complication rate of 40%. The most frequent complication identified by this group was misplacement of the ETT through the thyrohy­ oid membrane (i.e., above the larynx) , instead of through the CTM. Other complications included execution time greater than 3 minutes, unsuccessful tube placement, and signifi­ cant hemorrhage. One patient suffered a longitudinal fracture

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of the thyroid cartilage, due to attempted placement of an 8 .0-mm ID tube, resulting in significant long-term morbidity. In a similar series in 1 989, Erlandson40 reported a complica­ tion rate of 23%, related primarily to incorrect tube placement ( l Oo/o) and hemorrhage (8%) . Miklus et alY reported on 20 patients requiring emergency cricothyrotomy in the field. In this study, there were no complications of tube misplacement, significant hemorrhage, or long-term morbidity in survivors. Gillespie et al.42 reviewed 35 patients requiring emergency sur­ gical airway over a 6-year period and noted no differences in the overall complication rate berween emergency tracheotomy and cricothyrotomy. Of particular note was that there were no long-term complications in the patients that received cricothy­ rotomy and were not subsequently converted to tracheotomy.42 Although rare, fatal hemorrhages have been reported as a result of laceration of the cricothyroid artery.43 As this artery courses closer to the thyroid cartilage, there is a greater risk of hemorrhage if the incision is made in the upper half of the CTM. Other complications include SGS, dysphonia due to laryn­ geal damage, tracheal cartilage fracture, endobronchial intuba­ tion, pulmonary aspiration, recurrent laryngeal nerve injury, esophageal perforation and tracheo-esophageal fistula. 16 Tissue emphysema (including subcutaneous and mediasti­ nal emphysema) and barotrauma (including tension pneumo­ thorax) have been reported as complications of jet ventilation and establishment of a surgical airway.44 Weymuller45 cautions that only practitioners experienced with TTJV should attempt it in emergency airway management. He describes kinked or displaced transtracheal catheters, incoordination of respiratory effort, outlet obstruction, and distal airway secretions as the major problems encountered.

S U M MARY When confronted with the difficult airway, it should be recog­ nized that there are a multitude of techniques available to the practitioner. The wise practitioner is intimately familiar with the noninvasive techniques of difficult airway management and avoids the temptation to unnecessarily substitute surgical meth­ ods for the less invasive approaches. Even within the parameters of the techniques of surgical airway access, it is evident that the practitioner needs to decide which is most appropriate for the clinical situation at hand. Cricothyrotomy is a technique designed to address the true air­ way emergency. Some catheter insufflation techniques have the advantage of simplicity but all are temporizing at best. This remains the procedure of choice in children under 1 2 years, where cricothyrotomy is considered a relative contraindication. What is of vital importance for the practitioner is to rec­ ognize that "can't intubate, can't oxygenate" scenario can occur in a variety of clinical settings. As such, the practitioner needs to have in place the necessary knowledge, the necessary equip­ ment, and the clinical confidence to act. As it is unlikely that sophisticated gadgetry will be avail­ able in all circumstances, it is vital for the practitioner to be familiar with the technique that will most likely be successful with the minimum of equipment; this technique is undoubt­ edly cricothyrotomy. Commercial kits are now available that

can be used for either open, or Seldinger techniques, packaged as one. Scalpel bougie packages consisting of a scalpel handle/ blade and a bougie can also be readily available. These kits, or a suitable facsimile, should be available in all areas where the expert airway practitioner may be called upon to provide airway management, whether in the operating room, the emergency department, the intensive care unit or the hospital ward.

REFERENCES 1. Morens OM. Death ofa president. NEngl]Med. l 999;34 1 (24) : 1 84 5 - 1 849. 2. Ger R, Evans JT. Tracheostomy: an anatomico-clinical review. Clin Anat. 1 993;6:337 -34 1 . 3 . Brantigan CO, Grow JBSr. Cricothyroidotomy: elective use i n respiratory problems requiring tracheotomy. J Thorac Cardiovasc Surg. 1 976;7 1 ( 1 ) : 72-8 1 . 4 . Salmon LF. Tracheostomy. Proc Royal Soc Med. 1 975;68 (6) : 347-3 56. 5 . Brettonneau P. Des Inflammations Speciales du Tissu Muqueux. Paris; 1 826. 6. Merriam-Webster Online Dictionary. 7. Alberti PW. Tracheotomy versus intubation. A 1 9th century controversy. Ann Otol Rhino! Laryngol. 1 984;93(4 pt 1 ) : 333-337. 8. Trousseau A. Recherches sur !a Tracheotomie. Paris; 1 8 5 1 . 9 . Jackson C . Tracheotomy. Laryngoscope. 1 909; 1 9:285-290. I 0. Jackson C. High tracheotomy and other errors: the chief cause of chronic laryngeal stenosis. Surg Gynaecol Obstet. 1 9 2 1 ;32:392. 1 1 . ClerfLH. Chevalier Jackson. Arch Otolaryngol. March 1 966;83(3):292-296. 12. Boyd AD, Romita MC, Conlan AA, Fink SO, Spencer FC. A clinical eval­ uation of cricothyroidotomy. Surg Gynecol Obstet. 1 979; 1 49(3): 365-368. 13. Greisz H, Qvarnstorm 0, Willen R. Elective cricothyroidotomy: a clinical and histopathological study. Crit Care Med. 1 982; 1 0 (6): 387-389. 14. Holst M, Hedenstierna G, Kumlien JA, Schiratzki H. Elective cricothy­ roidotomy. A prospective study. Acta Oto-Laryngol. 1 983;96(3-4) :329-33 5 . 1 5 . Francois B, Clave! M, Desachy A , Puyraud S, Roustan J, Vignon P. Complications of tracheostomy performed in the ICU: subthyroid trache­ ostomy vs surgical cricothyroidotomy. Chest. 2003; 1 23 ( 1 ) : 1 5 1 - 1 5 · 8. 1 6. Boon JM, Abrahams PH, Meiring JH, Welch T. Cricothyroidotomy: a clinical anatomy review. Clin Anat. 2004; 1 7 (6):478-486. 1 7. Mace SE. Cricothyrotomy. j Emerg Med. 1 988;6(4) :309-3 1 9 . 1 8 . Talving P, DuBose J, lnaba K , Demetriades D. Conversion o f emergent cricothyrotomy to tracheotomy in trauma patients. Arch Surg. 20 1 0; 1 4 5 ( 1 ) : 87-9 1 . 1 9. Kress TO, Balasubramaniam S . Cricothyroidotomy. Ann Emerg Med. 1 982; I I (4) : 1 97-20 1 . 20. Bair AE, Chima R. The inaccuracy of using landmark techniques for crico­ thyroid membrane identification: a comparison of three techniques. Acad Emerg Med. 20 1 5;22(8):908-9 1 4 . 2 1 . Kwofie K , Hung 0, Hung C, Hung D. The use of neck surface land­ marks (Launcelott Creases) to locate the cricoid cartilage. Anesthesiology. 2008; 1 09: 1 76. 22. Bennett JD, Guha SC, Sankar AB. Cricorhyrotomy: the anatomical basis. J R Col! Surg Edinb. 1 996;4 1 ( 1 ) : 57-60. 23. Dover K, Howdieshell TR, Colborn GL. The dimensions and vascular anatomy of the cricothyroid membrane: relevance to emergent surgical airway access. Clin Anat. 1 996;9(5):29 1 -295. 24. McGill ], Clinton JE, Ruiz E. Cricothyrotomy in the emergency depart­ ment. Ann Emerg Med. 1 982; 1 1 (7) : 3 6 1 -364. 25. Blumberg NA. Observations on the pyramidal lobe of the thyroid gland. S Afr Med j. 1 9 8 1 ; 5 9 (26) : 949-9 50. 26. Kim OW, Jung SL, Baek JH, et a!. The prevalence and features of thyroid pyramidal lobe, accessory thyroid, and ectopic thyroid as assessed by com­ puted tomography: a multicenter study. Thyroid. 201 3;23 ( 1 ) : 84-9 1 . 27. Kim OW, Jung SL, Kim J , Ryu JH, Sung JY, Lim HK. Comparison between ultrasonography and computed tomography for detecting the pyramidal lobe of the thyroid gland: a prospective multicenter study. Korean ] Radio!. 20 1 5 ; 1 6 (2):402-409. 28. Kristensen MS. Ultrasonography in the management of the airway. Acta Anaesthesia! Scand. 20 1 1 ; 5 5 ( 1 0) : 1 1 5 5 - 1 1 73. 29. Elliott OS, Baker PA, Scott MR, Birch CW, Thompson JM. Accuracy of surface landmark identification for cannula cricothyroidotomy. Anaesthesia. 2 0 1 0;65 (9) : 8 8 9-894. 30. Aslani A, Ng SC, Hurley M, McCarthy KF, McNicholas M, McCaul CL. Accuracy of identification of the cricothyroid membrane in female subjects using palpation: an observational study. Anesth Analg. 20 1 2; 1 1 4(5):987-992.

Cri cothyroto my 3 1 . Lamb A, Zhang J, Hung 0, et al. Accuracy of identifYing the cricothyroid membrane by anesthesia trainees and staff in a Canadian institution. Can j Anaesth. 20 1 5 ;62(5):495-503. 32. Prasad A, Yu E, Wong DT, Karkhanis R, Gullane P, Chan VW. Comparison of sonography and computed tomography as imaging tools for assessment of airway structures. J Ultrasound Med. 20 1 1 ;30(7):965-972. 33. Cook TM, Woodall N, Frerk C; Fourth National Audit Project. Major com­ plications of airway management in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society. Part 1 : anaesthesia. Br J Anaesth. 201 1 ; 1 06(5) : 6 1 7-63 1 . 34. Cook TM, Woodall N , Harper J , Benger J ; Fourth National Audit Project. Major complications of airway management in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society. Part 2: intensive care and emergency depart­ ments. Br j Anaesth. 201 1 ; 1 06(5): 632-642. 35. Wong DT, Mehta A, Tam AD, Yau B, Wong J. A survey of Canadian anesthesiologists' preferences in difficult intubation and "cannot intubate, cannot ventilate" situations. Can ] Anaesth. 20 1 4; 6 1 (8) : 7 1 7-726. 36. Heard AM, Green RJ, Eakins P. The formulation and introduction of a 'can't intubate, can't ventilate' algorithm into clinical practice. Anaesthesia. 2009;64 (6) :60 1 -608. 37. Gaufberg SV, Workman TP. New needle cricothyroidotomy setup. Am j Emerg Med. 2004;22 ( 1 ) : 37-39. 38. Gaughan SD, Ozaki GT, Benumof JL. A comparison in a lung model of low- and high-flow regulators for transtracheal jet ventilation. Anesthesiology. July 1 992;77 ( 1 ) : 1 89- 1 99. 39. Elliott WG. Airway management in the injured child. IntlAnesthesiol Clin. 1 994;32 ( 1 ) :27-46. 40. Erlandson MJ, Clinton JE, Ruiz E, Cohen J. Cricothyrotomy in the emer­ gency department revisited. j Emerg Med. 1 989;7(2): 1 1 5- 1 1 8 . 4 1 . Miklus RM, Elliott C, Snow N. Surgical cricothyrotomy in the field: expe­ rience of a helicopter transport team. journal Trauma. 1 989;29(4) : 5 06-508. 42. Gillespie MB, Eisele DW Outcomes of emergency surgical airway proce­ dures in a hospital-wide setting. Laryngoscope. 1 999; 1 0 9 ( 1 1 ) : 1 766- 1 769. 43. Schillaci CR, Iacovoni VF, Conte RS . Transtracheal aspiration complicated by fatal endotracheal hemorrhage. N Englj Med. 1 976;295 (9) :488-490. 44. Smith RB, Schaer WB, Pfaeffie H . Percutaneous transtracheal ventilation for anaesthesia and resuscitation: a review and report of complications. Can Anaesth Soc]. 1 975;22(5) : 607-6 1 2 . 45. Weymuller EAJr, Pavlin E G , Paugh D, Cummings CW. Management o f difficult airway problems with percutaneous transtracheal ventilation. Ann Otol Rhino! Laryngol. 1 987;96 ( 1 pt 1 ) : 34-37.

SELF-EVALUATION QU ESTIONS 1 4. 1 . All o f the following are reported complications o f a surgi­ cal airway EXCEPT? A. Hemorrhage B. Fracture of the thyroid cartilage C. Subglottic stenosis D. Vocal cord damage E. Mediastinal emphysema 1 4.2. Which of the following is NOT a useful predictor of a difficult cricorhyroromy? A. Fixed cervical spine flexion deformity B. Previous surgery of the neck C. Previous radiation to the neck D. Neck hematoma E. Cancer of the tongue 1 4 . 3 . Which of the following is NOT true about establishing a surgical airway in children? A. A greater risk of posterior perforation while perform­ ing a surgical airway in children. B. A greater incidence of subglottic stenosis. C. The laryngeal prominence does not develop until adolescence. D. The height of the cricothyroid membrane is consider­ ably larger in children than adults. E. Increase risk of cricoid cartilage damage.

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Tracheotomy Timothy F. E. Brown and Liane B. Johnson

CAS E PRESENTATION

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CASE PRESENTATION A 58-year-old male who completed radiation therapy for a large supraglottic tumor 4 months ago now presents to the Emergency Department in significant respiratory distress with biphasic stridor. He is somewhat agitated and prefers to remain in a semi-sitting position. He is cachectic, a heavy smoker but nondrinker. He is not taking any medications and has no aller­ gies. His oxygen saturation is 88% on room air and improves to 94% with supplemental oxygen. He is cooperative enough to allow the otolaryngologist to perform a flexible nasopha­ ryngoscopy at the bedside, which reveals extensive supraglottic edema, completely obscuring identification of normal laryn­ geal landmarks, and any visualization of the upper airway (see Figure 1 5 - 1) . The otolaryngologist suspects there is recurrent tumor below this edema.

I NTRODUCTION • What Is the Historica l Evol ution of the

Development and Acceptance of Surgical Tracheotomy?

Tracheotomy is one of the oldest surgical procedures in recorded history and often viewed historically as intimidating and inher­ ently dangerous to perform. The Italian anatomist and surgeon Fabricius ab Aquapendente ( 1 537-1 6 1 9) stated, "The terrified surgeons of our times have not dared to exercise this surgery and I also have never performed it. Even the mention of this operation terrifies the surgeons; hence it is called the "scandal of surgery." 1 Tracheotomy was performed during the diphtheria epidemic in the early 1 9th century for cases of severe upper air­ way obstruction. In 1 833, Armand Trousseau, a French inter­ nist, recounted his experiences with the procedure: "I have now performed the operation in more than 200 cases and I have the satisfaction of knowing that one fourth of these operations were successful." 2 Faint praise indeed! Throughout the 1 9th and into the early 20th centuries, tracheotomy was employed only in extreme circumstances, in order to avoid total upper airway obstruction from infectious processes involving the larynx and upper trachea. The "modern" technique of tracheotomy was formally presented and described in detail by Chevalier Jackson3 in 1 909. Among other pearls, Dr. Jackson emphasized precise surgical technique with ade­ quate exposure, careful hemostasis, and the prevention of dam­ age to the cricoid cartilage. He is generally credited with vastly decreasing the morbidity and mortality of the procedure as well as the long-term complication of subglottic stenosis. With the introduction of endotracheal intubation, posi­ tive pressure ventilation and ongoing advancements in inten­ sive care leading to requirements for long-term ventilation, we

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TAB L E 1 5- 1 .

I n d ications

Contraindications

Pro l o n g e d o r expected pro l o n g e d i ntu bati o n I na b i l ity to m a n a g e secret i o n s

Severe coag u l opathy

Fa c i l itation o f ve nti l ator s u p po rt

F I G U R E 1 S - 1 . E ndoscopic view of the u pper a i rway s h ow i n g exten s ive su pra g l ottic e d e m a , com p l etely obsc u r i n g identification of norma l l a ry ngea l l a n d m a rks, and a ny v i s u a l ization of the u pper a i rway.

D i sta l tra c h e a l pat h o l ogy I nadeq uate tra i n i n g i n t h e p roced u re

I na b i l ity to i ntu bate Adj u n ct to maj o r head a n d neck s u rg e ry Adj u n ct to s i g n ifica nt head a n d n e c k tra u ma Severe o bstru ctive s l e e p a p nea

have seen a significant shift in the indications for tracheotomy. Some two-thirds of all tracheotomies performed today are now done semi-electively for critically ill patients in an intensive care setting. While a common procedure, tracheotomy can be one of the most straightforward or one of the most challenging operations to perform. Many factors, both anatomic and disease related, add considerable variability and unique challenges to the same procedure in different patients.

percutaneous tracheotomy techniques, these are always contra­ indicated in cases where the airway is not already secured (see Chapter 33) .

• What Are the Clinica l Indications and

Endoscopic visualization of the larynx reveals almost complete airway obstruction due to edema and potential tumor. Given the patient's current obstructive pathology, the attempted use of bag-mask-ventilation, extraglottic device, or intubation would likely lead to a disastrous outcome for this patient. Any manipulation of such a precarious airway puts the patient at greater risk of complete obstruction. Tracheotomy is the only realistically viable option for this patient. Although the airway is tenuous, he is currently not in extremis, and hence the safest location for the procedure is in the operating theatre.

Contraindications to Performing a Tracheotomy?

Indications for a tracheotomy can broadly be divided into four main categories: ( 1 ) to relieve upper airway obstruction from either acute or chronic causes; (2) to promote improved pulmo­ nary toilet; (3) to provide an airway access for long-term venti­ lation; and ( 4) to promote weaning from the ventilator. Current indications have been summarized by the American Academy of Otolaryngology, Head & Neck Surgery4 in the 2000 Clinical Indications Compendium (see Table 1 5 - 1) . There are very few absolute contraindications provided the practitioner has suffi­ cient and appropriate training in tracheotomy (see Table 1 5- 1 ) . • I n This Clin ica l Situation, Why Would

a Tracheotomy be Favored Over a Cricothyrotomy or a Percutaneous Dilational Tracheotomy?

Due to the obstructive nature of this patient's edema and likely underlying tumor, there is uncertainty regarding its inferior extent, which makes a cricothyrotomy potentially dangerous as there is an increased risk of transecting tumor in this loca­ tion. With its more inferior entry into the airway, a traditional tracheotomy is hence a safer option to ensure that the airway will be secured below the level of obstruction. With regards to

AI RWAY MANAGEMENT • What Are the Options to Secure This

Challenging Ai rway and Provide Oxygenation for Th is Patient?

• Should the Tracheotomy be Performed

Awake or U nder Genera l Anesthesia?

This patient is teetering on the edge of obstructing his airway. A general anesthetic is not the best initial option as there are no viable options to access the airway other than a controlled tracheotomy. An awake look could be performed, but again increases the risk of triggering total upper airway obstruction. In the authors' opinion, topicalization of the airway in these tenuous circumstances may precipitate immediate complete airway obstruction as the subjective perception of airflow by the patient is essential in maintaining airway patency (see sec­ tion "Can Topical Lidocaine Anesthesia of the Upper Airway Cause Airway Obstruction?" in Chapter 3) . An awake tracheotomy under local anesthesia in the operat­ ing room is the only realistically viable option for this patient.

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• Yo u Ma ke Arrangements to Ta ke the

Patient U rgently to th e O perat i n g Room But Are To l d There Wi l l be a 20-M i n ute Delay. What S u p p l ementary S u p portive Care Ca n You Offer Th is Patient i n the Mea ntime?

There are a variety of supportive steps that can be taken to reduce the risk of total upper airway obstruction without manipulat­ ing the airway or upsetting the patient. The importance of this latter point is often underestimated. The increasingly anxious patient is likely to generate higher inspiratory airflow velocity resulting in increased resistance across the obstruction poten­ tially leading to total airway obstruction. This "dynamic airway obstruction" can be seen in a crying newborn due to the pliabil­ ity of the underlying cartilaginous structures of the larynx, and in inflamed laryngeal tissues as is seen in croup and epiglottitis. Keeping the patient calm in a sitting position is critical in these situations as upper airway obstruction is a most distress­ ing condition. Hence, the simplest measures, such as constant calm reassuring dialogue with the patient cannot be overem­ phasized. Likewise, very careful use of low-dose anxiolytics could be entertained though it should be recognized that they may attenuate reflexive active airway opening maneuvers and precipitate total airway obstruction. Supplemental oxygen is obviously important although it is often better delivered via nasal prongs as a mask can some­ times feel smothering to patients in this situation. The use of heliox, which has a density six times lighter than air by replacing atmospheric nitrogen with helium, will promote a significant reduction in airflow resistance through a narrowed airway (improved "orifice flow") . The decrease in turbulent flow leads to increased airflow by as much as 50% in a nar­ rowed airway.5 Aerosolized epinephrine, by way of its mucosal vasoconstrictive effects, may be of some benefit although care must be taken not to aggravate the patient's anxiety. The use of intravenous corticosteroids, while helpful in the medium term, does not work quickly enough in impending upper airway obstruction.

• When Planning for a Tracheotomy, How

Do You Accurately Identi fy the Critical Landmarks and Prepare the Surgical Site?

Accurate palpation of laryngeal landmarks is critical. Surgical access to the airway using any technique can go horribly wrong quickly if the practitioner is unfamiliar with precise landmark­ ing (see Figures 1 5-2-1 5-4) . Patient factors such as gender, body habitus, positioning, overlying or underlying pathology, prior neck surgery, or radiation can make this essential step either relatively straightforward or extremely difficult. These factors capture all of those identified by the SHORT mnemonic in section "Difficult Cricothyrotomy: SHORT" in Chapter 1 . Key landmarks to identify and mark include the hyoid bone, the superior notch of the thyroid cartilage, the crico­ thyroid membrane, cricoid cartilage, and the sternal notch. Immediately below the cricoid, tracheal rings may or may not be palpable depending on the amount of soft tissue anterior to them. Typically, women have smaller, more obtuse thyroid cartilage laminae, and hence differentiation between the cricoid and thyroid cartilages can be challenging. Multiple methods for accurately defining the landmarks have been described but there are three techniques that the authors find the most consistently reliable. With the patient's neck in a neutral (not extended) position: ( 1 ) Starting from the hyoid bone (see Figure 1 5-2) Beginning palpation superiorly with the thumb and index or middle finger on either side of the hyoid bone allows for

• The O perat i n g Room Is N ow Ready a n d

the Patient H a s B e e n B ro u g ht I nto the O R . H ow S h o u l d Yo u Position a n d Prepa re t h e Patient for t he Trach eotomy?

During a normal routine tracheotomy, the patient should be positioned supine with the neck extended and a shoulder roll placed to elevate the larynx and bring more of the trachea up into the neck out of the chest. This standard position cannot be safely utilized in this case; however, as lying fully recumbent will worsen the airway patency, increase the patient's anxiety, and will not be tolerated by the patient. Thus, positioning the patient with the upper body reclined from a totally erect posi­ tion to the extent permitted by the patient's symptoms will lessen the risk to the airway obstruction while still allowing for reasonable surgical exposure.

F I G U R E 1 5-2. Pa l patio n s u periorly with the th u m b a n d i ndex o r m i d d l e fi n g e r o n e i t h e r s i d e of the hyoid bone a l l ows fo r s u bseq u e n t positive pa l pation of t h e thyroid n otch with t h e i ndex fi nger, fou n d j u st below i n the m i d l i ne, w i t h the cricothyroid mem bra n e and cricoid ca rt i l ages fol l ow i n g i nferiorly.

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subsequent positive palpation of the thyroid notch with the index finger, found just below in the midline, with the cricothyroid membrane and cricoid cartilages follow­ ing inferiorly. (2) Finger stacking approach to the cricoid (see Figure 1 5-3) If the practitioner approximates the patient's finger breadth, then placing the tip of the fifth digit in the sternal notch and "stacking" the remaining fingers vertically, the upper edge of the index finger will be at the level of the cricoid cartilage. (3) Second neck crease (see Figure 1 5-4) Most individuals have three neck creases. The midline of the second neck crease (see also Figure 1 4-2) can be used as a landmark to allow for rapid, directed palpation of the cricoid cartilage. This technique is best used as an adjunct to the above approaches.

F I G U R E 1 5-3. F i n g e rs Sta c k i n g A pproa c h : If the practitioner pl aces the t i p of the fifth d ig it i n the ste r n a l n otc h a n d "sta c k i n g " the rema i n i n g fi n g e rs vertica l l y, the u p per edge o f the i ndex fi n g e r wi l l be a p p roxi mately at the l evel o f the c r ic o id ca rti lage.

Once the landmarks have been definitively identified, the incision should be marked and inj ected with local anesthetic with epinephrine. Waiting at least 1 0 minutes for the vaso­ constrictive effects is strongly advised providing the clini­ cal scenario allows for it. While always important, bleeding can be particularly troublesome in cases where the patient is awake and the airway potentially is unstable. After sterile prepping of the skin, the patient should be draped in a man­ ner that allows for the patient's face to be uncovered so as not to induce anxiety and allow for easy reassurance from the surgical and anesthetic teams. The authors typically do not inj ect local anesthetic into the airway itself as the loss of sensation of airflow can result in significant anxiety on behalf of the patient and hasten an airway crisis (dynamic upper airway obstruction) . Typically, if injection of local anesthetic into the airway is entertained, it is made once the trachea is exposed and controlled entry into the airway is imminent.

• Without Delving I nto the I ntricacies of a l l

the Techn ical Steps I nvolved in Perform ing a Tracheotomy, What Are Some of the I mportant Differences Which May be Encou ntered When Perform ing a Formal Tracheotomy Versus a Cricothyrotomy?

F I G U R E 1 5-4. Most i n d ivid u a l s have th ree neck creases. The m id­ line of the secon d neck crease ca n be u sed a s a l a n d m a rk to a l l ow for ra pid, d i rected pa l pation of the cricoid ca rti la g e (arrow).

The most significant difference is the site of entry into the air­ way. A tracheotomy incision is placed through the anterior wall of the trachea itself, preferably between the second and third tracheal rings. Occasionally, anatomic limitations may neces­ sitate a more superior site of entry; however, avoiding contact with the inferior aspect of the cricoid cartilage is generally encouraged to decrease the risk of perichondritis and subse­ quent development of subglottic stenosis. Unlike the cricothyroid membrane, which can be located superficially in the neck with only skin and subcutaneous tissue overlying it, locating the trachea becomes increasingly challeng­ ing as it descends toward the thoracic inlet. The main elements making the trachea more difficult to palpate are an increasing

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Ai rway Tec h n i q ues

thickness of the overlying soft tissues, increasing mobility of the trachea as it extends distally, and the fact that the trachea slopes progressively more posteriorly as it approaches the tho­ racic inlet. This is particularly notable in patients who have short necks and large barrel chests, where the trachea can rap­ idly seem to descend like a mineshaft extending ever deeper into the neck. In contrast to cricothyrotomy, there are other important structures that can be encountered during a tracheotomy. The anterior cervical veins can be the source of significant and trou­ blesome bleeding if not identified and retracted or ligated. The thyroid isthmus is often encountered and needs to be reflected or divided depending on its size and position. It is quite a vas­ cular structure and careful hemostasis is required when divid­ ing it to avoid intraoperative or postoperative bleeding. The innominate artery can occasionally extend superiorly into the tracheotomy field and its identification and avoidance are obvi­ ously essential as inadvertent injury can result in catastrophic bleeding. Finally, innumerable vital structures can be encoun­ tered in the lateral neck should one's dissection stray off the midline overlying the trachea.

PERIOPERATIVE COMPLICATIONS A N D TRO U B LESH OOTI NG • Following Placement of the Tracheostomy

Tube, No End-tidal C02 Waveform Is Obtained and the Patient Cannot be Manually Venti lated. How Do You Manage the Apparent Loss of You r Airway?

The most likely reason for this scenario is that the distal tip of the tracheostomy tube is not in the airway. This is what is termed a "false passage." Its prompt recognition and correction are essential. In this situation, the tracheostomy tube has been placed anterior to the trachea in the upper mediastinum. Some would advocate confirming the false passage by passing a flex­ ible bronchoscope or suction catheter. However, the urgency of the clinical situation rarely allows for this luxury. The authors advocate leaving all retractors in place until ade­ quate C0 return and ventilation are confirmed, making rapid 2 removal of the tracheostomy tube and subsequent replacement easier. If there is doubt as to the ability to replace the tube under direct vision, a Seldinger technique over an Eschmann tracheal introducer (also known as a "bougie") or an exchange catheter, or preferably a flexible endoscope will help guarantee proper placement into the tracheal lumen. Making a multitude of rushed attempts employing the same technique can lead to an expansion of the false passage and a rapidly worsening air­ way situation. • What Anatomic Challenges I ncrease the

Likelihood of Creating a False Passage?

Factors that can make this complication more likely include challenging anatomy such as a short, obese neck with a cor­ respondingly greater distance separating the skin from the trachea, scarring or mass lesion anterior to the trachea, or

significant bleeding in the operative field. Unstable airway situ­ ations can lead to the surgical team rushing the placement of the tracheostomy tube, which increases the odds of placing it in a false passage. Choosing a tracheostomy tube, which is too short can lead to the distal tip being inadequately seated or even outside of the tracheal lumen, a particular risk in patients with obese necks. • Fol lowing Tracheoto my, t h e Patient

I s Tra nsferred to the Recovery Room, B reat h i n g Sponta neously, i n Sta ble Con d ition. Yo u Are Paged 20 M i n utes Later as the Patient's Work of Breat h i n g Has I ncreased . The Recovery Room N u rse I s U na b l e to Mainta i n H i s Oxygen Sat u ration Above 85% Desp ite S u pplem enta l Oxygen. What I s Most L i kely Occu rri ng Now?

One way to troubleshoot this early postoperative complication is to divide it into a problem with the tracheostomy tube or a problem with the patient. Firstly, the tracheostomy tube might be blocked by one of three mechanisms: blood clot or mucous plug, abutment of the distal end to the posterior tracheal wall (seen if the tube is malpositioned or too short) , or if the tube has accidentally slipped back out of the tracheal lumen or even back into a false passage. Secondly, it is important to rule out a primary respiratory issue such as a pneumothorax or pneumomediastinum, which can result from aggressive peritracheal dissection during the procedure or from aggressive attempts at bag-ventilation when the tracheostomy tube was sitting in the false passage. It is important to also rule out post-obstructive pulmonary edema (POPE) , which is a distinct possibility given the sudden relief of our patient's upper airway obstruction. • The Tu be Appears We l l -Seated With

No Dista l Obstruct io n. The Patient Has Decreased, Coa rse B reath Sounds B i l atera l ly. A Porta ble Chest Radiograph I s Done at the Bedside a n d Confirms P u l m o n a ry Edema. H ow Do You Manage Th is?

Post-obstructive pulmonary edema can occur after sudden relief of upper airway obstruction. Sudden negative interstitial pressure leads to hydrostatic forces rapidly flooding the alveoli, resulting in hypoxemia and the classic clinical finding of pink, frothy fluid either emanating from the tracheotomy or endo­ tracheal tube (ETT) , or expectorated by the patient. The most salient aspect is the rapid development of the edema post relief of the obstruction. Treatment is straightforward once POPE is positively identified by relieving the inciting factor, nega­ tive airway pressure, and effectively countering it with positive pressure ventilation. While primarily not an issue of vascular overload, the use of diuretics can hasten the improvement. Typically, POPE will resolve relatively quickly, within 24 to 48 hours (see also Chapter 6 1 ) .6-8

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• Fol lowi ng S uccessfu l Treatment of t h e

•

Patient's S u p ra g l ottic Tu mor, H e I s Successfu l ly Deca n n u lated . I n Futu re, I f H e Were to Req u i re I nt u bation for Any Other Reason, What Potential Anato m i c Alterations M a y I m pede You r Attempt at Endotracheal I ntu bation?

When a patient returns t o the operating room with a history of a previous tracheotomy, two questions should come to mind: Firstly, why did the patient require a tracheotomy originally and secondly, are there any residual effects on the airway as a result of the previous tracheotomy? The reason for ascertaining why the tracheotomy was ini­ tially placed is to know whether it was necessary due to an upper airway obstruction, such as supraglottic, glottis, or subglottic scarring or stenosis or other anomaly which might impact future attempts at intubation. Likewise, tracheotomies themselves, either percutaneous or open, can result in injury to the trachea itself such as stenoses, infractures, tracheomalacia, or suprastomal granulation tissue. If there is any doubt as to the presence of underlying upper airway injury, a flexible endos­ copy prior to intubation should be considered.

Optimizing ventilation during a surgical procedure when a patient has an indwelling tracheostomy tube might be best pro­ vided by changing to a cuffed, non-fenestrated tracheostomy tube or an ETT placed through the stoma to facilitate ventilation of the patient. If an inner cannula is present, it needs to remain in situ as this is the portion that connects to the anesthesia circuit. •

Room With a Tracheostomy Tu be Already in Place, Are There Any Special Considerations When Securing the Ai rway for Ventilation During the Surgery?

When a patient presents for anesthesia with a tracheostomy tube already in place, a number of things should be clarified initially. TAB L E 1 5-2.

What is the diameter of the tracheostomy tube and how fresh is the tracheotomy stoma? When temporarily changing out the tracheostomy tube, it is important to exchange for a cuffed ETT with one of a simi­ lar diameter. Maintaining a similar outer diameter is impor­ tant to prevent contracture of the stoma around a smaller tube during the case, making replacement of the tracheotomy tube more challenging following the surgical procedure. This is more likely to happen in less mature stomas and in longer cases. A relatively fresh stoma (less than 2 weeks old) should be treated with caution and ideally have a surgeon familiar with tracheotomy present to help replace it. Tracheotomy sto­ mas that have been present for months or years have usually developed a mature tracheocutaneous tract, which is quite safe.

•

• When a Patient Presents to the Operating

Is the existing tracheostomy tube a cuffed or uncujfed tube? Is it a fenestrated tube and does it have an inner cannula?

What safety adjuncts should be available when manipulating the tracheotomy stoma? Ensuring the obturator is inserted when repositioning the tracheotomy tube and having a Trousseau dilator (or even a nasal speculum) to spread the edges of the tracheotomy stoma in the room is important to facilitate tube exchange without incident. The use of a tube exchange catheter to facilitate the change of tracheostomy tubes would be par­ ticularly helpful for a fresh stoma (less than 2 weeks old) .

Com p l icatio n s of Trach eotomy

I ntraoperative

Early Postoperative

Late Postoperative

Hemorrhage Anterior j u g u l a r ve i n s, thyro i d i st h m u s, i n n o m i nate a rtery

Acciden tal decannulation M ost d a n g e ro u s in the fi rst 5 d ays. The i n it i a l tra c h eoto my tu be s h o u l d be sutu red in p l a ce sec u rely

Tracheoinnominate artery fis tula Catastrophic bleed i n g a n d l ife threate n i n g . Typica l ly 2-4 weeks postoperative. Senti n e l b l eed poss i b l e

A ir dissection P n e u m ot h o rax, p n e u m o m ed i asti n u m, s u bcuta neous e m p hysema

Hemorrhage Wo u n d i nfectio n/g ra n u l ation tissue fo rmation

Suprastomal gran uloma formation R i s k of b l ocki n g sto ma d u ri n g tra c h eoto my t u be c h a n g e o r i m ped i n g voca l izati o n

Damage to other structures Recu rrent l a ry n g e a l n e rves, cricoid ca rti l a g e, ra re r i s k to ca roti d s h eath structu res, m e m b ra n o u s trachea a n d eso p h a g u s

Tube blockage B l ood, m u cous, or d ried secret i o n s D i sta l e n d o f t u be a djacent t o a nte rior o r poste rior tra c h e a l wa l l

Tracheal or subglottic stenosis

False passage

Pos t-obstructive pulmonary edema

Tracheal ring in fractures Tracheoesophageal fis tula Persisten t tracheocutaneous fis tula (following decann ulation)

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276

Ai rway Tec h n i q ues

Also having extra tubes available and another set of experi­ enced hands should help ensure a smooth transition of one tube for the next. •

Any clinicalpearls to share when exchanging a tracheostomy tube for an endotracheal tube? If utilizing an ETT, an awareness of the proximity of the carina to the stoma is important as it is very easy to place the tip of the tube too far distally and inadvertently intubate the right mainstem bronchus. Correct placement of the tip of the ETT can be confirmed by auscultation, or preferably by a flexible bronchoscope. Once the ETT is positioned properly in the trachea, it should be secured properly with tapes or with sutures to the skin of the chest wall.

• What Compl ications are Associated With

Tracheotomy?

Complications of tracheotomy can be divided into three cat­ egories: intraoperative, early postoperative, or late postoperative (Table 1 5-2) .

S U M MARY The case reviewed in this chapter is a fairly common scenario in an otolaryngology practice, particularly in larger tertiary care cen­ ters where head and neck oncology patients are routinely treated. While other methods of surgically accessing the airway, such as percutaneous tracheotomy and cricothyrotomy, have gained popularity and have their own distinct advantages, this case-based review has reemphasized why a formal surgical tracheotomy remains the gold standard in challenging airway situations.

REFERENCES I. Karparvar Z, Goldenberg D. Tracheotomy Management: A Multidisciplinary Approach. Excerpt, New York, NY: Cambridge University Press; 2 0 1 1 :2. 2. Kost K, Myers N. Tracheostomy; Operative Otolaryngology: Head and Neck Surgery. (Vol. 2, Ch. 68) . Philadelphia, PA: Saunders; 2008: 577-594. 3 . Jackson C. Tracheotomy. Laryngoscope. 1 909; 1 9:285-290. 4. American Academy of Otolaryngology - Head & Neck Surgery (AAO­ HNS). 1 999 Clinical Indicators Compendium. AAO-HNS Bull, 1 999, October.

5. Hashemain SM, Fallahian F. The use of heliox in critical care. lnt} Crit I!In lnj Sci. 20 1 4;4: 1 3 8- 1 42. 6. Lemyze M, Mallat J. Understanding negative pressure pulmonary edema. Intensive Care Med. 20 1 4;40: 1 1 40- 1 1 43 . 7. Bhattacharya M, Kallet RH, Ware L B , Matthay MA. Negative-pressure pulmonary edema. Chest. 20 1 6; 1 50:927-933. 8. Fremont R, Kallet R, Matthay M, Ware L. Postobstructive pulmonary edema. Chest. 2007; 1 3 1 : 17 42- 1 7 46.

SELF - EVALUATION QU ESTIONS 1 5 . 1 . All o f the following are reported complications o f a surgi­ cal airway EXCEPT: A. hemorrhage B. fracture of the cricoid cartilage C. subglottic stenosis D. direct inj ury to the vocal cords E. pneumomediastinum 1 5 .2. All of the following are potentially likery causes of a patient having decreased oxygen saturation levels in the recovery room following an awake tracheotomy

EXCEPT: A. pneumothorax B. accidental decannulation C. tracheotomy tube blocked by blood or secretions D. post-obstructive pulmonary edema E. pulmonary embolus 1 5 . 3 . Which of the anatomic structures below is the least important to identifY prior to making your incision dur­ ing a tracheotomy? A. hyoid bone B. tracheal rings C. suprasternal notch D. cricoid cartilage E. thyroid notch

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C H A PT E R 1 6

What I s Unique About Airway Manage ment in the Pre - Hos pita l Settin g ? Mark Vu, David Petrie, Michael F. Murphy, and Erik N. Vu

CAS E PRESENTATION

278

U N IQ U E PRE-HOSP ITAL ISSU ES . . . . . . . . . . . . . . . . . .

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AI RWAY CON S I D E RATIO N S . . . . . . . . . . . . . . . . . . . . . . . 279 MANAG EMENT O F T H E AI RWAY I N TH I S CAS E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282 S U MMARY .

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SELF-EVALUATIO N Q U ESTI O N S . . . . . . . . . . . . . . . . . .

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jurisdiction to another within a country. For clarity, we will define four discrete levels of airway management provided in an EMS system. Each level assumes proficiency in the skills of the previous: •

•

•

CASE PRESENTATION On a stormy night in the countryside, a 72-year-old male driver falls asleep at the wheel and strays into on-coming traffic. A transport truck trying to avoid him strikes his small car. The car is crushed and the driver is trapped inside. Emergency Medical Services (EMS) are activated. Basic life support (BLS) medics and fire fighters arrive on scene within 1 0 minutes. The patient is conscious with a Glasgow Coma Score of 1 3, BP 80/40 mm Hg, HR 1 00 bpm, RR 26 breaths per minute, and 0 2 satura­ tions of 82% prior to oxygen therapy.

U N IQ U E PRE - HOSPITAL ISSU ES • What Level of Airway Management Can We

Expect From Pre-Hospital Care Providers?

"A" is the cornerstone in the ABCs, which form the foundation of BLS training for all pre-hospital care providers. The type of training and skill sets varies significantly from country to country and the provider mix may be different from one

•

First aid providers or "First Responders"-trained to apply supplemental 0 2 by face mask and perform artificial ventila­ tion, typically bag-mask-ventilation (BMV) , although in some jurisdictions extraglottic devices (EGOs) may be preferred at this level as first-line devices in place of BMV Airway adjuncts at this level may include oral- and naso-pharyngeal airways. BLS providers-more experienced with BMV, and these pro­ viders use EGOs, particularly CombitubeTM' King LTM, and Laryngeal Mask Airways (LMA) in some systems. Advanced life support (ALS) providers-typically perform laryngoscopy (direct or indirect) and endotracheal intubation, with or without the use of facilitating drugs, such as sedative­ hypnotics and neuromuscular blocking agents. Emergency cricothyrotomy training is often included at this level. Critical care providers (e.g. , typically Air Medical Transport or Critical Care Transport team members)-are permitted to perform rapid sequence intubation (RSI) using direct laryngoscope and usually other advanced airway techniques such as indirect laryngoscopy (e.g. , video-laryngoscopy) and cricothyrotomy. In some j urisdictions (most notably Europe and Australia) , teams include other health care profession­ als, including registered nurses and physicians, as members of these multidisciplinary teams.

• How Are Airway Management Protocols and

Eq u ipment Determined in Pre-Hospita l Care Systems?

In most North American systems, pre-hospital care providers perform delegated medical acts based on standardized medical protocols. In many European systems, physicians may be the usual pre-hospital care providers and, therefore, are less likely

What Is U n i q u e About Ai rway M a nagement i n the Pre-Hospita l Setti n g ?

dependent on protocols. While protocols ought to reflect best clinical evidence, from a practical perspective they are often lim­ ited by cost, training, competency maintenance, and space con­ straints. Over the past several years, there has been a movement in some jurisdictions away from protocols, and more toward treatment guidelines, allowing advanced pre-hospital care pro­ viders to exercise clinical j udgment when managing airways. These guidelines allow for more flexibility to achieve predefined physiologic goals pertaining to airway management, with less emphasis on technical imperatives formerly used as markers of successful (or unsuccessful) airway management. For example, modern guidelines define successful airway management as the maintenance of oxygenation and ventilation by various means, other than simply placing an endotracheal tube. Protocols or guidelines approved by the medical direc­ tor of the EMS system determine the equipment necessary in pre-hospital care practice. The type and range of equipment available for managing the difficult airway in the pre-hospital setting are usually limited when compared to in-hospital set­ tings. Even basic equipment, such as the Endotracheal Tube Introducer (ETI; e.g. , the Eschmann Tracheal Introducer, also known as the "gum-elastic bougie"), 1 laryngoscope blades, and endotracheal tubes (ETT) in an array of types and sizes, may be limited. Alternate intubating devices, such as the Intubating Laryngeal Mask Airway (ILMA or LMA-Fastrach'") or light­ wands (e.g., Trachlight'"), often are not available due to limitations in space, training opportunities, cost, resterilization, and issues of skills maintenance. Rescue devices, such as the esophageal­ tracheal Combitube'", LMA, and the LMA-Unique'" (the dis­ posable LMA) , and the King LT are becoming more popular because they are relatively inexpensive, disposable, and are con­ sidered easier to use by pre-hospital care providers at varied levels of training. 2• 3 However, extraglottic ventilation devices may not be appropriate in some clinical situations, particularly if adequate ventilation calls for an increase in peak airway pres­ sure beyond the capabilities of a device to achieve an adequate seal, if the patient is sufficiently responsive to reject the device, or if protection against aspiration is preferred.4 Surgical airway management devices5 must be available in any system providing RSI. Critical Care EMS systems often differ from many ground systems because they carry more advanced equipment, such as the GlideScope'" video-laryngoscope, or other devices. • What Unique Environ menta l Considerations

Do Pre-Hospital Care Providers Face When Managing the Airway?

The practitioner managing the airway is often confronted with an array of circumstances unique to the out-of-hospital envi­ ronment, including: •

•

•

A chaotic scene; A dangerous scene (e.g. , flood, fire, radiation, electrical wires down, toxic environment, assailant on the loose, etc.) ; Access t o the patient and the airway which may b e challeng­ ing due to a variety of factors: an ongoing extrication; position of the patient (e.g., seated, upside down, etc.) . I n non-trauma airway management, positioning may also •

•

•

present a problem (e.g., intubation performed lying prone and leaning on the elbows) . Even with the patient on a stretcher in an ambulance or helicopter, an optimal posi­ tion for airway management may be difficult to achieve. Other uncontrollable environmental conditions: darkness inhibits full airway assessment and obscures sub­ tle nonverbal communication cues among providers; bright sunlight may present similar problems, especially when tracheal intubation (TI) is performed using a laryn­ goscope or a lightwand; extremes of weather may present problems for patients, practitioners, and equipment (e.g., freezing temperature effects on plastic and metal objects) . an uncontrolled tactical environment, in which EMS may be deployed with police and be required to limit access to patients, or limit interventions performed in the various phases of tactical emergency casualty care; spectators, family, or friends of patients may require skilled handling. Lack of other essential equipment for airway management, for example, suction; Uncontrolled human behavior in the pre-hospital setting may further interfere with airway management decisions and procedures: distraught relatives challenging the focus of pre-hospital care providers; knowledgeable and skilled assistants may be unavailable; well-meaning first-aiders or bystander physicians may hamper efforts with inappropriately timed or out-of-con­ text comments or actions. •

•

•

•

•

•

•

•

•

•

Finally, management of an airway in the pre-hospital envi­ ronment may have to be carried out amid the most adverse of surroundings and circumstances, for example, a crime scene, on a dance floor, in a stadium, etc.

Back to our case: ALS responders arrive on the scene 15 min­ utes later. 1he patient's level of consciousness is decreasing and he remains hypotensive. BLS providers have skillfolly assisted ventila­ tions with the BMVwhile other skilled rescuers attempt to extricate the patient from the wreckage. 1he GCS is now 9, BP 80/40 mm Hg, HR 120 bpm, and 02 saturation 88 %. AI RWAY CO N S I D E RATIONS • What Are the Patient Factors That Influence

Airway Management Decisions of a Pre-Hospita l Care Provider?

There are three related elements governing airway management in the field environment: time, anatomy, and (patho-) physiol­ ogy (i.e., the clinical state of the patient) . Ti m e Fa ctors: When I s I t Bette r to Wa it?

All emergency airway management situations share this feature. In other words, they are "context sensitive" (see Chapter 7) . It is well appreciated that geographic proximity to a hospital or trauma center does not correlate with out-of-hospital time (e.g. , extrication delays) , and as such, the pre-hospital care provider must often differentiate between an "indication" for a given

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airway management technique, and the "need" to actually per­ form that intervention. Consider, for example, the following three cases: •

•

•

A 40-year-old male with sudden collapse two blocks away from a hospital, GCS 6, with no cough or swallowing reflex, 0 saturations of 99%, and normal airway anatomy; 2 The same 40-year-old male with sudden collapse, on a moun­ tain side, 2 hours away from the nearest hospital, GCS 6, with no cough or swallowing reflex, 0 saturations of 99%, 2 normal airway anatomy, and the only means to extricate the patient is via Helicopter Emergency Medical Services (HEMS) response, or; The same 40-year-old man in a house fire who has stridor, 0 2 saturations of 70%, and evidence of upper airway burns.

In the first patient above, the decision to intubate immedi­ ately will depend on the anatomical assessment and time con­ siderations. For example, if the transport time to a hospital is very short, it might be reasonable to wait (i.e., oxygenate and ventilate with BMV, protect with suction) until arrival at the ED where more resources are available. Training must empha­ size that airway management means gas exchange and it does not always require intubation. We must avoid the trap of the "technical imperative"-just because it can be done, it should be done. In fact, there is growing evidence that in certain situa­ tions pre-hospital intubation may not necessarily improve out­ come and may be detrimental. 6•7 On the other hand, in the second patient, despite stable physiology and no predictors of difficult anatomy, due to pro­ longed out-of-hospital time and the anticipation of aeromedi­ cal evacuation with limited access to the patient, it would be reasonable to take the time on scene to place an advanced air­ way for protection during flight and until arrival at a receiving hospital. Likewise, in the third patient, with predicted difficult laryn­ goscopy and anticipated progression of airway edema, time is critical. A quick decision must be made and the provider must confidently follow the Emergency Difficult Airway Algorithm (Figures 2. 1 0 and 2 . 1 3 in Chapter 2). Anato m i c Fa cto rs: H ow to Pred i ct Diffi c u lties in Different Ai rway M a n a g e m e n t Tec h n i q u es?

The airway assessment is essentially an attempt to predict difficult direct and indirect laryngoscopy and intubation, difficult BMV, difficult EGD placement, and difficult crico­ thyrotomy based on an examination of external anatomic fea­ tures (see sections "Difficult BMV: MOANS," "Difficult DL Intubation: LEMON," "Difficult VL intubation: CRANE," "Difficult Use of an EGD: RODS," "Difficult Cricothyrotomy: SHORT" in Chapter 1 ) . While recognizing that it may not be possible to assess the airway of some patients (e.g., unrespon­ sive patients) , this evaluation is as crucial a component of pre­ hospital airway management as it is in hospital. It permits the airway practitioner to make appropriate airway management plans (Plans A, B, and C) that are most likely to be successful. The patient with acceptable oxygen saturations and a short transport time, with or without predictors of difficult laryn­ goscopy and intubation, might be better served by a rapid

transport to the nearest ED with more resources. This reflects context-specific decision balancing technical abilities (i.e., I can intubate) with physiologic goals (i.e., the patient is oxygenating and ventilating adequately) , but also takes into consideration the poor predictive value of some of our airway assessment tools. In other words, though one may have predictors of easy direct laryngoscopy, once C-spine precautions are put in place, the patient may in fact be difficult to intubate through standard means. Should clinical or time considerations pre­ clude rapid transport for in-hospital airway management, the Emergency Difficult Airway Algorithm directs one to weigh carefully whether RSI, sedation, or awake intubation would be most appropriate. If any of these is unsuccessful, one should move promptly to the Failed Airway Algorithm (Figure 2. 1 1 in Chapter 2) . Situations in which difficulty is predicted and air­ way management is urgently indicated may be better handled by an early call through dispatch for scene backup. Most pre-hospital ALS and critical care providers are famil­ iar with the necessity for an airway evaluation prior to each intubation, particularly if medications are to be administered to facilitate the procedure. However, this may be limited to predictors of difficult laryngoscopy and intubation rather than difficulty in other airway techniques (see Chapter 1 ) , such as video-laryngoscopy, EGDs, difficult BMV, and difficult surgi­ cal airway. C l i n i ca l Facto rs: H ow Do t h e C l i n i ca l Co n d ition a n d Pres u m ed D i a g n o s i s Affect Ai rway M a n a g e m e nt Decis i o n s ?

There are two clinical considerations i n managing a difficult airway in the field setting: the indication for intubation and the underlying pathophysiology. Indications for endotracheal intubation in the pre-hospital environment are similar to those in any other emergency.8 1. 2. 3. 4. 5. 6.

failure to maintain adequate oxygenation; failure to maintain adequate ventilation (C0 removal) ; 2 failure to protect the airway; the need for neuromuscular blockade; the anticipated clinical course; uncompensated shock.

In practice, many patients may have more than one indica­ tion for endotracheal intubation. Underlying Pathophysiology: The indications for intubation among various EMS systems may differ. The most common indication (up to two-thirds of all intubations) in a typical ground EMS system is cardiac arrest.9 The remainder tend to be split evenly among respiratory failure (asthma, chronic obstructive lung disease, congestive heart failure, pulmonary embolism, pneumonia, anaphylaxis) , non-trauma CNS con­ ditions (coma, intracranial bleed/stroke, seizure, overdose) , trauma (head injury, chest injury, neck injury, blood loss caus­ ing shock) , and shock states (sepsis, cardiogenic, hypovolemic) . Helicopter EMS (HEMS) (also called rotorcraft Air Medical Transport [AMT] ) rarely responds to primary cardiac arrest calls. These critical care teams are trained to manage patients who may require more advanced airway procedures, or those with more complex pathophysiology.

What Is U n i q u e About Ai rway M a nagement i n the Pre-Hospita l Setti n g ?

I n certain circumstances, a patient may have a n indication for intubation but circumstances, such as predicted difficult air­ way and a short transport time to the ED, may sanction BMV and suction until intubation is possible. The weighing of "risk versus benefit" is illustrated in the example above (40-year-old man with a collapse and a short transport time vs. long transport time, vs. burn with time-sensitive pressures) . Even in the face of an accepted indication for intubation, the potential benefits of pre-hospital intubation must be weighed within the context of the environment, time, anatomy, and pathophysiology. • What Alternatives Do Pre-Hospita l Providers

Have in Managing a Difficult Airway?

Effective BMV technique (including two-handed mask hold requiring two providers if available or necessary) is essential to the pre-hospital care provider, particularly when the airway could be difficult and the transport time relatively brief. Despite considerable controversy in the literature, the gold standard for definitive airway control remains the cor­ rect intratracheal placement of a cuffed ETT. According to the "Recommended Guidelines for Uniform Reporting of Data from Out-Of-Hospital Airway Management," 10 there are four methods by which this can be achieved: direct oral laryngos­ copy and intubation, nasotracheal intubation, TI via an oral rescue techniques (e.g. , intubating LMA) , and surgical rescue techniques (transtracheal jet ventilation and cricothyrotomy) . These four methods may each be modified by five variables: •

•

•

•

•

oral approach-no facilitating sedative drugs or paralytics; nasal approach-no facilitating sedative drugs or paralytics; sedation-facilitated intubation-without the use of paralytics; RSI-with the use of paralytics and induction agents; other intubation techniques (e.g., digital, lightwand, etc.) .

The actual number of options available to a given EMS system is driven by evidence-guided, rationale-based medical oversight, and limited by local culture, protocols, training, and equipment. There is ample evidence that endotracheal intubation is not a benign intervention in the hands of inexperienced person­ nel. 1 1 ' 13 Newer airway devices such as the LMA, King LT", and the Combitube'" have been introduced and validated in the pre-hospital care setting.4·14'20 These devices may be employed in two ways: as an alternative to endotracheal intubation in the cardiac arrest (or deeply comatose) patient by all level of provid­ ers4·15·19'2 1 or as a rescue device in the setting of failed intubation by ALS or critical care providers. 14·16 An emerging alternative to endotracheal intubation in the respiratory failure patient is pre-hospital noninvasive positive pressure ventilation (NIPPV) . Several case series have shown continuous positive airway pressure (CPAP) or bi-level ventila­ tion (BiPAP) to be feasible and potentially beneficial in the pre­ hospital setting. 22'24 Current evidence supports the use of CPAP in the pre-hospital setting for high-pressure pulmonary edema (i.e., CHF) . 2 5 Pre-hospital critical care teams will often also use BiPAP in hypercapneic respiratory failure (e.g. , secondary to COPD) . 26 Furthermore, based on case series and physiological principles, BiPAP can be used as a denitrogenation technique

by critical care paramedics prior to transitioning to endotra­ cheal intubation and formal mechanical ventilation. 27· 28 • What Are the Cha llenges in Terminology

Associated With Pre-Hospital Ai rway Management?

Increasing attention is being paid to the many aspects of pre­ hospital airway management. Research, discussion, education, innovation in both devices and approaches have expanded. It is quite apparent that one approach does not fit all clinical situations in the ideal in-hospital environment, so it is folly to assume that it is any less complex in the pre-hospital setting in which there are more variables to consider. The clinical choices involved in airway management in the field setting may well be limited by personnel training, the realities of maintaining com­ petence, and the devices and drugs available to field personnel. Using "patient outcome," rather than procedural outcome as the measure of success of airway management, one can begin to construct some useful definitions. Inaccurate use of terms in three different risk/benefit clinical issues often make the selection of the best airway management method to proceed with in any clinical situation difficult. The three spectrums of risk/benefit are: 1 . Pharmacology: which drug or combination of drugs should be administered; 2. Procedure/equipment: what procedure/equipment to use to facilitate the placement of a device; 3. Device: what device is most appropriate to oxygenate/ventilate the patient. These confusions often lead to incorrect comparisons in research studies. If these three components are carefully sepa­ rated from each other, it becomes apparent that interpretation of the results of a study comparing RSI versus EGDs as part of a Rapid Sequence Airway is difficult. 29 The exact terminol­ ogy eventually used is less important than the need to achieve consensus and consistency. However, separating these three decision points will be imperative, recognizing that the initial decision or plan may change with evolving clinical situations. The most obvious use of vague terminology is in the area of the pharmacology of airway management. Many drugs and combinations of drugs can be used in facilitating pre-hospital airway procedures, particularly in what has been called "Rapid Sequence lntubation,"30 "Rapid Sequence Airway," 29 "Drug­ Facilitated lntubation,"31 "Drug-Assisted lntubation,"32 "Deep Sedation versus Awake lntubation,"33 and others. For simplic­ ity, these variations can be grouped into three categories:

1 . Rapid Sequence, in which paralysis is preceded by an induc­ tion agent appropriate to the clinical state of the patient and the situation; 2. Sedation, in which the intent is to provide sedation, analge­ sia, or both; 3. Awake, in which topical anesthesia of the upper airway allows for lower sedative dose. It might be said that clinically the difference between 2 and 3 above is "qualitative"; but the intent, and therefore the use

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of drugs, is clearly different. A lack of understanding of these differences can be both educationally confusing and clinically catastrophic. The use of deep sedation in the patient with a dif­ ficult airway without backup plans and essential equipment can lead to apnea, aspiration, profound physiologic disturbances, a failed airway and ultimately, poor patient outcomes. • Should Tl Even be Performed in the Field?

Both in and out of the hospital, inappropriate ventilation and inadequate oxygenation have been identified as primary con­ tributors to preventable morbidity and mortality. It would seem reasonable, then, to assume that endotracheal intubation should be the gold standard in pre-hospital airway manage­ ment. However, there has been considerable controversy as to whether patients requiring endotracheal intubation should have TI performed in the field or deferred until arrival at hospital. There are several issues that arise from this controversy: •

•

•

Trauma victims-There continues to be skepticism as to whether the intubation of trauma victims in the field improves survival. During the 1 980s, it was generally felt that invasive airway management was ineffective in improv­ ing survival in urban environments but might be effective in longer transport environments.34 Studies published dur­ ing the 1 990s gave conflicting results. 35-40 It might, at the very least, be anticipated that endotracheal intubation would be advantageous in patients with severe head injury. Early studies provided no clear direction7,41-46 and a recent large trauma registry study found that pre-hospital intubation was associated with adverse outcomes after severe traumatic brain injury (TBI) ? However, covariate adjustment in the same study suggests that management of the airway by an air medical team may improve outcomes. Unfortunately, as Zink and Maio47 pointed out in an accompanying editorial, this is a retrospective association rather than a causation study. Importantly, these TBI studies raise questions about the down­ stream effects of drug choices, drug dosages, the physiology of transitioning from negative pressure-spontaneous ventilation to positive pressure ventilation, the type of positive pressure ven­ tilation employed, and positive end-expiratory pressure (PEEP) among other things. Cardiac Arrest-In cardiac arrest patients, the issue of efficacy of ETT remains unresolved.48-5 2 To further add to the con­ troversy, a study involving out-of-hospital cardiac arrest vic­ tims showed that patients who received CPR with only chest compressions had comparable survival outcome compared to those who received chest compression and mouth-to-mouth ventilation.53 A large prospective study to determine the incremented benefit of introducing ALS (including intuba­ tion) to a previously optimized system did not show a mor­ tality benefit in cardiac arrest patients. 54 Furthermore, other observational studies have reported signals that advanced airway management is an independent predictor of worse neurological recovery after out-of-hospital cardiac arrest.55 Children-Early studies in children showed that TI by para­ medics was associated with higher failure and complication rates than that in adults. 56 Results of subsequent studies have confirmed these early findings. 6•36·57-60 The only prospective

trial to investigate the effectiveness of ground paramedic in performing TI in children showed that there was no increase in survival following TI as compared to that in the group treated with BMV6 This same study revealed concerns about TI displacement and inability to recognize this catastrophic complication.6 Many authorities maintain that these latter studies reflect inadequate training of paramedical person­ nel in TI of children. Furthermore, the literature does not resolve whether the field intubation of children with head injuries improves their outcome. 61•62 In the final analysis, the emergency intubation of children is an uncommon and anxiety-provoking event for most paramedics. Both of these factors are likely to increase performance stress and failure rates, compared to the intubation of adults. Recent studies have presented data and formed conclusions that challenge the basic, time-honored dogma of EMS airway management and question the best approach to the compro­ mised airway in the pre-hospital environment. Furthermore, the development of other airway adjuncts (e.g. , Combitube'", King LT", LMA'", and CPAP) coupled with a reemphasis on standard BMV has changed the priority for pre-hospital endo­ tracheal intubation and is a clear sign of maturity and success of the EMS . It is becoming clear that airway management training and maintenance-of-competency programs are vital, as they will affect both the psychomotor skill development, psychomotor skill decay, and context-specific decision making that reflects current best practice. Other issues such as equipment availabil­ ity, the air versus ground environment, and the logistics associ­ ated with rural as opposed to urban critical care transport/EMS suggest that a single, rigid approach to EMS airway manage­ ment is inappropriate and cannot be supported.

Now to our case: ALS medics are unsuccessful in obtaining a definitive airway. Two !Vs have been placed and a normal saline (NS) bolus administered. The patient has just been extricated (30 minutes later), boarded, and collared. The critical care crew has just landed at the scene. The patient now has a GCS of 7, a clenchedjaw, BP 90/60 mm Hg, HR 120 bpm, and an 02 satura­ tion of90 % with assisted BMV with oxygen supplement. MANAG E M E NT OF T HE AI RWAY I N THIS CAS E • Pre-Hospita l RSI-What Does the Evidence

Show?

The HEMS crew on the scene has the training and capability to perform an RSI on appropriate patients as part of their clinical mandate. This includes the use of an induction agent, followed in rapid sequence by a neuromuscular blocking agent and vaso­ active agents (e.g., phenylephrine) , in order to optimize intu­ bating conditions and peri-intubation physiology, in order to increase the chances of successful endotracheal intubation and smooth transition to positive pressure ventilation.30 Until recently, the evidence in the EMS literature has not supported the use of RSI. Several recent, well-designed stud­ ies of ground systems have consistently shown suboptimal outcomes, or no difference in outcome, in patients suffering acute severe TBI in whom RSI is used to facilitate endotracheal

What Is U n i q u e About Ai rway M a nagement i n the Pre-Hospita l Setti n g ?

intubation.6•7•1 2,41•63 Head injury was deliberately chosen in these studies because prior reports have suggested that optimal oxygenation and ventilation of these patients improve out­ comes. Therefore, it was assumed that successful endotracheal intubation would demonstrate a benefit.64 A case-control study of pre-hospital RSI of the severely head injured patients in 2003 identified increased mortality and morbidity in the RSI group when compared to patients who had TI performed in the ED following transport without RSI.63 Though this study had methodological limitations that preclude generalizing their findings to all EMS systems that use RSI, an important mes­ sage was the reemphasis on protecting physiologic goals during airway management (i.e., Sp0 , ET C0 , etc. by any means) , 2 2 and de-emphasizing technical goals (i.e., achieving Tl) . There have been attempts to determine the reasons for the poor outcomes associated with RSI in ground EMS services. These explanations have included: •

•

•

•

increased on-scene time (average 1 5 minutes in one study)65; lack of adequate training of the paramedics6,45·63; inappropriate hyperventilation and unrecognized hypoxemia during induction; paralysis and attempts at intubation.1 2

Despite recent studies showing the lack of efficacy of RSI in the ground EMS systems, a distinct pattern of improved out­ comes has emerged in the subpopulation of those patients in whom air medical transport (HEMS) had been utilized?·66-69 It would appear that the key to improved outcomes lies in the initial training and maintenance of competence (cognitive and psychomotor skills) for the pre-hospital providers. • How Should a Critical Care Transport Tea m

Proceed With th e Management of t h e Airway in Th is Patient?

The HEMS crew elects to perform RSI using succinylcholine (1.5 mg·kg-1) and etomidate (0.2 mg·kg-1). A Grade 3 view of the laryngeal structures is obtained with no improvement of the view with the use of laryngeal manipulation. An Eschmann Tracheal Introducer is placed into the trachea and a 7.5-mm ID ETT is passed over it. A qualitative, colorimetric end-tidal C02 (ETCO:J detector confirms tracheal tube placement. Adequate oxygen satu­ ration is maintained during the procedure, and post-intubation systolic blood pressure is 90 mm Hg. To prevent hyperventilation, quantitative in-line ETC02 monitoring is instituted post intuba­ tion and during transport. Other options for the pharmacologic approach to RSI in this patient could include rocuronium as the paralytic ( 1 . 0 mg·kg- 1); ketamine (no longer contraindicated in head injury, and in many jurisdictions, is now the induction agent of choice in both adult and pediatric TBI populations) ; and propofol (relatively contraindicated in hypovolemia) as the induction agents; or a 50-50 mixture of these two induction agents. Because of its slow onset and associated hypotensive side effects at standard induction doses, midazolam may not be an ideal induction agent in EMS. Although the concept of "non­ paralytic RSI" has been enshrined in some EMS systems, Tl after the administration of an induction agent alone (without

paralytic agent) is not supported by the literature and is not generally recommended?0 In fact, success rates in intubation are generally lower and complications are higher with deep sedation when compared with RSI.71-73 It should be emphasized that full C-spine immobilization ought to be maintained during the intubation procedure. In the event TI failed, most EMS providers in this setting would use an EGO (e.g., King LTM, LMA, Combitube'M) . Cricothyrotomy (or an alternative percutaneous technique in young children) is a technique used by most advanced EMS providers. Continuous monitoring of oxygen saturation and ETC0 should be main­ 2 tained during transport in order to prevent hypoxemia, inad­ vertent hyper- or hypo-ventilation, or extubation. • H ow Do Pre - Hospital Providers Confirm

a n d Maintain I ntratracheal Placement of the ETT?

The consequences of an unrecognized, misplaced ETT may be devastating. Given the chaotic environment, the difficulty in employing the usual clinical verification signs, and the increased movement and transfer of the patient, it is more difficult to recog­ nize an esophageal intubation or dislodged endotracheal intuba­ tion in the pre-hospital setting than elsewhere. The exact number of unrecognized esophageal intubations is uncertain since many EMS systems do not gather these data. Inadvertent esophageal intubation rates in EMS have ranged from 1 %74 to 25%75 based on verification of tube positioning by emergency physicians on arrival at the hospital. Very low rates are found in systems with specific tube verification protocols, ETC0 monitoring, 2 and ongoing performance improvement to ensure compliance. Unacceptably high rates are found when such protocols are not in place or tube placement verification devices are not available. Pre-hospital care providers can confirm correct placement of the ETT in three ways: clinically, with mechanical esophageal detector devices, or with a qualitative or quantitative ETC0 2 detector. Clinical signs include visualization of the tube going through the vocal cords, mist condensation on the ETT, aus­ cultation of lungs and stomach, etc. Esophageal detection devices (EDDs) may take the form of a bulb or syringe aspi­ ration device (Figure 1 6- 1A and B) . Carbon dioxide detec­ tors may be colorimetric (Figure 1 6-2) , digital capnometers, or continuous graphic display capnographs. End-tidal C0 2 verification of correct ETT placement is the standard of care in EMS ?6 The limitations of each of these techniques must be rec­ ognized. Carbon dioxide detection techniques tend to be less accurate in identifying correct placement of the ETT in patients with circulatory arrest, with reported false negative rates (car­ bon dioxide not detected, tube in the trachea) as high as 30% to 3 5 %.77 In patients with some circulation, carbon dioxide detection is reliable in confirming correct placement 99% to 1 00% of the time.77-81 Finally, one should also be aware that ETC0 does not always correlate with PaC0 • As such, one 2 2 should use caution employing ETC0 alone during "hyperven­ 2 tilation trials" in severe TBI patients with evidence of increased ICP, as ETC0 may not accurately reflect PaC0 , pH, and the 2 2 impact on cerebral blood Bow.

283

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Pre-Hospita l Ai rway M a n a g e m e n t

• What Is the Post-I ntubation Care of This

Patient?

F I G U R E 1 6- 1 . Esop hageal d etection d evices ( E D D ) : (A) the b u l b type o f E D D a n d ( B ) t h e syri n g e type o f E D D.

After successful endotracheal intubation, the ETT should be secured properly. It is also important to monitor oxygenation, ventilation, and hemodynamics continuously. Hyperventilation and the associated drop in PaC0 may adversely impact cere­ 2 bral blood flow and perfusion in patients with closed head inju­ ries and hypotension in head injured patients has a significant negative impact on survival.64 It is also critical to consider the additive impacts of positive pressure ventilation and sedative/ hypnotic medications on hemodynamic stability. Transition from negative-pressure, spontaneous ventilation to positive­ pressure, assisted ventilation increases intrathoracic pressure and decreases venous return to the heart. In the context of pre-hospital patients with hypovolemia, this change in respiratory physiology can have a significant negative effect on blood pressure and end­ organ perfusion. Moreover, loss of sympathetic tone after induc­ tion of anesthesia with hypnotic agents commonly results in a drop in blood pressure. The change in hemodynamics following intubation should be carefully anticipated and monitored for, in order to prevent secondary end-organ injury and maintain organ perfusion. Strategies to mitigate hemodynamic variability include close attention to delivered tidal volume, minimizing external PEEP when appropriate, rapid volume administration (used by BLS and ALS providers) , and the use of vaso-active agents, such as phenylephrine (used by clinicians) .

S U M MARY

F I G U R E 1 6-2. Th i s fig u re d e picts a typica l q u a l itative e n d t i d a l c a r b o n d ioxide d etection device.

Unlike carbon dioxide detection techniques, the EDD is not dependent on the presence of pulmonary blood flow. While some pre-hospital care systems use this device instead of carbon dioxide detection, the failure to detect esophageal intubation can be as high as 20%, suggesting that it should not be the only verification method used. 8 2 Physical examination techniques to verifY placement of an ETT in the trachea, while neither sensi­ tive nor specific, remain important adjuncts to carbon dioxide detection and EDD, particularly in patients in cardiac arrest. Finally, the migration of an ETT from the trachea to the esophagus during transport is an ever-present hazard. It has been demonstrated that the continuous monitoring of exhaled carbon dioxide during the pre-hospital phase of care minimizes the risk of unrecognized displacement.83 In summary, while carbon dioxide detection remains the most reliable method of verifYing tracheal placement of the ETT in pre-hospital care, the use of several methods of confirmation is superior to using just one method.

Airway management in the pre-hospital arena is difficult and fraught with realities that are unique to the environment. Individuals who provide pre-hospital airway management may vary widely in their training and experience. Although BMV is difficult to perform and may be replaced by EGOs which are easier to perform and equally as effective, BMV will continue to play a crucial role in pre-hospital airway management. Induction and neuromuscular blocking agents are widely used in pre-hospital care. It would appear that health care pro­ viders (and systems) who have extensive training in airway man­ agement, intubate frequently, and participate in intensive skills maintenance and quality programs have improved intubation success rates and patient outcomes compared to those who do not. As with any airway practitioner employing these procedures, it is crucial that the medications are used correctly in appropriate patients (i.e., not in patients predicted to have a difficult air­ way) and the airway practitioner is capable of rescuing the airway (Plan B and Plan C) should Plan A fail (the Failed Airway) . Initial and continuous confirmation of ETT placement by capnometry, the use of EDDs, and clinical methods represent the current standard of care in the pre-hospital arena. Finally, it is imperative that EMS training, protocols/guidelines, and maintenance of competencies for airway management empha­ size the importance of peri-intubation physiology and the impact of any airway intervention on oxygenation, ventilation, and hemo­ dynamic stability. These guiding principles should reflect the deli­ cate balance and relationship between technical imperatives with physiology-guided goal-directed resuscitation endpoints.

What Is U n i q u e About Ai rway M a nagement i n the Pre-Hospita l Setti n g ?

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Pre-Hospita l Ai rway M a n a g e m e n t 53. Hallstrom A , Cobb L , Johnson E , Copass M. Cardiopulmonary resusci­ tation by chest compression alone or with mouth-to-mouth ventilation. N Englj Med. 2000;342: 1 546- 1 5 5 3 . 54. Stiell IG, Wells GA, Field B, et al. Advanced cardiac life support i n out-of­ hospital cardiac arrest. N Engl} Med. 2004;35 1 :647-656. 5 5 . Hasegawa K, Hiraide A, Chang Y, Brown DF. Association of prehospital advanced airway management with neurologic outcome and survival in patients with out-of-hospital cardiac arrest. }AMA. 20 1 3;309:257-266. 56. Aijian P, Tsai A, Knopp R, Kallsen GW. Endotracheal intubation of pedi­ atric patients by paramedics. Ann Emerg Med. 1 989; 1 8 :489-494. 57. Boswell WC, McElveen N, Sharp M, Boyd CR, Frantz El. Analysis of prehospital pediatric and adult intubation. Air Med}. 1 99 5 ; 14: 1 2 5 - 1 27; discussion 7-8 . 5 8 . Brownstein D, Shugerman R , Cummings P, Rivara F, Copass M. Prehospital endotracheal intubation of children by paramedics. Ann Emerg Med. 1 996;28:34-39. 59. Su E, Mann NC, McCall M, Hedges JR. Use of resuscitation skills by paramedics caring for critically injured children in Oregon. Prehosp Emerg Care. 1 997; 1 : 1 23- 1 27. 60. Vilke GM, Steen PJ, Smith AM, Chan TC. Out-of-hospital pediat­ ric intubation by paramedics: the San Diego experience. J Emerg Med. 2002;22 : 7 1 -74. 6 1 . Cooper A, DiScala C, Foltin G, Tunik M, Markenson D, Welborn C. Prehospital endotracheal intubation for severe head injury in children: a reappraisal. Semin Pediatr Surg. 200 I ; I 0:3-6. 62. Suominen P, Baillie C, Kivioja A, Ohman J, Olkkola KT. Intubation and survival in severe paediatric blunt head inj ury. Eur J Emerg Med. 2000;7:3-7. 63. Davis DP, Hoyt DB, Ochs M, et al. The effect of paramedic rapid sequence intubation on outcome in patients with severe traumatic brain injury. J Trauma. 2003;54:444-453. 64. Chesnut RM, Marshall LF, Klauber MR, et al. The role of secondary brain injury in determining outcome from severe head inj ury. J Trauma. 1 993;34:2 1 6-222. 65. Ochs M, Davis D, Hoyt D, Bailey D, Marshall L, Rosen P. Paramedic­ performed rapid sequence intubation of patients with severe head inj uries. Ann Emerg Med. 2002;40: 1 5 9- 1 67. 66. Ma OJ, Atchley RB, Hatley T, Green M, Young J, Brady W. Intubation success rates improve for an air medical program after implementing the use of neuromuscular blocking agents. Am j Emerg Med. 1 998; 1 6 : 1 25 - 1 27. 67. Murphy-Macabobby M, Marshall WJ, Schneider C, Dries D. Neuromuscular blockade in aeromedical airway management. Ann Emerg Med. 1 992;2 1 : 664-668 . 68. Sing RF, Rotondo MF, Zanies D H , e t al. Rapid sequence induction for intubation by an aeromedical transport team: a critical analysis. Am J Emerg Med. 1 998; 1 6:598-602. 69. Slater EA, Weiss SJ, Ernst AA, Haynes M. Preflight versus en route success and complications of rapid sequence intubation in an air medical service. } Trauma. 1 998;45 : 5 88-592. 70. Werman HA, Schwegman D, Gerard JP. The effect of etomidate on airway management practices of an air medical transport service. Prehosp Emerg Care. 2004; 8 : 1 8 5 - 1 90. 7 1 . Lieutaud T, Billard V, Khalaf H , Debaene B. Muscle relaxation and increasing doses of propofol improve intubating conditions. Can j Anaesth. 2003;50: 1 2 1 - 1 26. 72. McKeating K, Bali IM, Dundee JW. The effects of thiopentone and pro­ pofol on upper airway integrity. Anaesthesia. 1 9 8 8;43:63 8-640. 73. McNeil !A, Culbert B, Russell I. Comparison of intubating conditions following propofol and succinylcholine with propofol and remifentanil 2 micrograms kg- ! or 4 micrograms kg- 1 . Br }Anaesth. 2000;8 5 : 623-625. 74. Bozeman WP. Hexter D, Liang HK, Kelen GD. Esophageal detector device versus detection of end-tidal carbon dioxide level in emergency intubation. Ann Emerg Med. 1 996;27: 595-599. 75. Katz SH, Falk JL. Misplaced endotracheal tubes by paramedics in an urban emergency medical services system. Ann Emerg Med. 200 1 ;37: 32-37. 76. O'Connor RE, Swor RA. Verification of endotracheal tube placement fol­ lowing intubation. National Association of EMS Physicians Standards and Clinical Practice Committee. Prehosp Emerg Care. 1 999;3 :248-250. 77. MacLeod BA, Heller MB, Gerard J, Yealy DM, Menegazzi JJ . Verification of endotracheal tube placement with colorimetric end-tidal C02 detection. Ann Emerg Med. 1 99 1 ;20:267-270.

78. Grmec S . Comparison of three different methods to confirm tracheal tube placement in emergency intubation. lntemive Care Med. 2002;28: 70 1 -704. 79. Li J. Capnography alone is imperfect for endotracheal tube placement confirmation during emergency intubation. J Emerg Med. 200 1 ;20: 223-229. 80. Ornata JP, Shipley JB, Racht EM, et al. Multicenter study of a portable, hand-size, colorimetric end-tidal carbon dioxide detection device. Ann Emerg Med. 1 992;2 1 : 5 1 8-523. 8 1 . Takeda T, Tanigawa K, Tanaka H, Hayashi Y, Goto E, Tanaka K. The assessment of three methods to verifY tracheal tube placement in the emer­ gency setting. Resuscitation. 2003;56: 1 5 3- 1 57. 82. Hendey GW, Shubert GS, Shalit M, Hogue B. The esophageal detector bulb in the aeromedical setting. } Emerg Med. 2002;23 : 5 1 - 5 5 . 83. Silvestri S, Ralls GA, Krauss B, e t al. The effectiveness of our-of-hospital use of continuous end-tidal carbon dioxide monitoring on the rate of unrecognized misplaced intubation within a regional emergency medical services system. Ann Emerg Med. 2005;45 :497-503.

SELF - EVALUATION QU ESTIONS 1 6. 1 . Rapid sequence intubation b y non-physician pre-hospi­ tal care providers A. is regulated by federal statute B. is safe in adults but not children C. is well established for paramedics D. is supported by the available evidence for critical care pre-hospital providers E. will replace EGOs in the foreseeable future 1 6.2. All of the following statements about "non-paralytic RSI" are correct EXCEPT A. some jurisdictions permit paramedics to employ this technique B. it has been proven to be safer than "paralytic RSI" C. it employs an induction agent at full dose but no neu­ romuscular blocking agent D. it provides an inferior view of the glottis E. it is felt to be more humane than intubating patients awake 1 6. 3 . All of the following statements regarding qualitative, colorimetric end-tidal carbon dioxide determination in EMS are correct EXCEPT A. continuous monitoring is indicated to identify inad­ vertent extubation during transport B. these devices enable one to adhere to the standard of care for confirmation of endotracheal intubation C. these devices are almost totally unreliable in patients having suffered a cardiac arrest D. they are more effective than esophageal detector devices in confirming endotracheal placement E. they are neither better nor worse than capnograpy in confirming correct endotracheal tube placement

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C H A PT E R 1 7

Airway Manage ment of a Patient with Traumatic Brain Injury (TB I ) J. Adam Law, Edward T. Crosby, and Andy Jagoda

CAS E PRESENTATION

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PRE-HOSP ITAL CARE .

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EMERGE NCY DEPARTM ENT MANAG EMENT . . . . . . . . . 288 C-S P I N E CO N S I DERATIONS . . .

290

POST-I NTU BATION CO N S I D E RATI O N S

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S U M MARY . . . . . . . . . . . .

295

SELF-EVALUATIO N Q U ESTIO N S .

299

PRE-HOSPITAL CARE After ensuring scene safety, the immediate management of the patient with traumatic brain injury (TBI) in a field setting should focus on stabilizing and maintaining oxygenation and blood pressure. All patients with head injuries have potential cervical injury and should be assessed for the need to be immo­ bilized. A fundamental premise in pre-hospital care is to antici­ pate and prepare for eventualities such as vomiting, seizures, and aberrations of blood pressure or oxygenation. • Should Tracheal I ntubation be Performed

in the Field for Th is Patient?

CASE PRESENTATION An Advanced Life-Support Emergency Services unit brought a 3 5-year-old male into the emergency department (ED) "back­ boarded and collared." The patient was an unrestrained driver who was ejected from his car when it ran off the road and hit a tree. When a paramedic team arrived 1 0 minutes after the crash, the patient had a blood pressure (BP) of 90/50 mm Hg, heart rate (HR) 1 00 beats per minute (bpm) , respira­ tory rate (RR) 20 breaths per minute, and oxygen saturation (Sp0 ) 95% on room air. His Glasgow Coma Scale (GCS) 2 score was 7 (opened eyes to pain-2, moaned-2, abnormal flexion-3) . Pupils were equal and reactive, and his mouth was tightly clenched. The patient was given oxygen via nasal prongs and a non-rebreathing face mask. Although the patient exhib­ ited episodic agitation with combative behavior during trans­ port, intravenous (IV) access was obtained and an infusion of Lactated Ringer's was begun.

In this patient, ensuring oxygenation via a patent airway is of paramount importance. Indications for a field tracheal intu­ bation include inadequate ventilation or oxygenation despite supplemental oxygen administration, or the inability of the patient to protect the airway. A relative indication for intuba­ tion is the risk of losing the airway during transport. Transport time and type, for example, ground versus aeromedical, must be considered. Studies of the outcome of pre-hospital airway management have yielded conflicting results leaving little con­ sistent evidence indicating a benefit to field tracheal intuba­ tion in most patients with head injury who are oxygenated and ventilating1-7; as discussed in Chapter 1 6, pre-hospital airway management protocols are currently being further investigated. In the case presented, the patient was maintaining oxygen­ ation and ventilation. His clinical course could not be certain and it was reasonable for the field team to consider tracheal intubation. However, the patient had clenched teeth and was predicted to also pose difficult direct laryngoscopic intubation based on his short neck and cervical spine (C-spine) immo­ bilization. A decision to intubate would involve the use of a rapid sequence intubation (RSI) protocol; considering the short transport time, field RSI was not indicated.

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• What Add itional Considerations Are

I mposed by Field Cond itions?

Several other priorities in clinical care must be addressed by the field team after initial patient stabilization. Ci rc u l a t i o n

Hypotension is a critical factor associated with an increased morbidity and mortality in patients with head injuries.8 '9 Blood pressure in the field should be monitored closely with the goal of avoiding or correcting hypotension (systolic BP < 90 mm Hg in adults) . 1 0 This patient presented with a field BP of 90/60 mm Hg. With the poor outcome associated with hypotension in TBI patients, fluid resuscitation becomes a priority. However, the field team must weigh the benefit of securing IV access in the field with the risk of delayed transport to a trauma center. Ideally, IV access and fluid administration should occur during expeditious transport to the trauma center. It should be empha­ sized that isolated brain injury rarely accounts for hypotension in trauma patients with multisystem injury1 1 ; rather, if present, as with this patient, hemorrhage elsewhere must be suspected. N e u ro l o g i c D i sa b i l ity: I ntra c ra n i a l Press u re ( I C P) a n d C-S p i n e

ICP: Th e GCS o f 7 , 1 0 minutes after the injury, i s not pre­ dictive of the patient's clinical course or prognosis (other than an increased likelihood of C-spine injury) . The patient did not have unequivocal evidence of increased ICP since the pupils were equal and reactive and the motor response was decorticate, not decerebrate. As such there was no indication for paramed­ ics to provide any field intervention for managing elevated ICP with modalities such as tracheal intubation/hyperventilation, mannitol, or hypertonic saline. 1 2-14 A potential pitfall in the management of the TBI patient is to assume that trauma is entirely responsible for altered mental status. Consideration must be given to the reversible causes of altered mental status, for example, hypoglycemia and drug tox­ icity, in addition to hypoxemia and hypotension. C-spine immobilization: All patients with blunt trauma to the torso or neurological dysfunction should be suspected of having spinal cord injury until proven otherwise. Although neurologic impairment is fully manifest at the time of injury in most patients with vertebral injury, 14 the implications of an unidentified spine injury are such that routine use of immobilization devices is indicated. Secondary neurological inj uries are reported to occur in 1 0% to 30% of patients with delayed diagnosis who are not immobilized at time of entry into care15·16 and in 2% to 1 0% of those who are immobi­ lized. 17 Three studies suggest that the probability of associated C-spine injury is at least tripled with GCS scores of 8 or less . 1 8-2 0 Research into techniques for optimal cervical immo­ bilization supports the use of a rigid cervical collar that incor­ porates the upper thorax, stabilization blocks on either side of the head, and a long spine board for transport. 2 1' 22 Spinal immobilization is not without consequence in that patients are at risk of aspirating if they seize, vomit, or lose protective air­ way mechanisms. In addition, collars have consistently been demonstrated to increase ICP and may worsen ICP dynamics

in patients with head injury, 22-26 probably by interference with cerebral venous drainage. 27 Finally, spinal immobilization has the potential to complicate airway management by worsen­ ing the laryngeal view obtained at direct laryngoscopy (DL) . 28 With the history of TBI and GCS of 7, the presented patient was at significant risk of C-spine trauma and required full C-spine immobilization. A n a l g es i a/Sedation

Patients with severe head injuries can experience episodes of agitation and combativeness, both of which tend to increase ICP and can pose safety risks to both the patient and the para­ medic crew. Sedatives, such as benzodiazepines and opioid analgesics, are typically employed but, if given, the GCS score should first be determined, and the status of oxygenation and ventilation closely monitored after administration. Tra n s po rt Deci s i o n s

An early priority i n the management o f patients with moderate or severe brain injuries is transportation to the closest facility providing immediate access to neuroimaging and neurosurgical services. Patients with severe TBI transported to trauma centers without the availability of prompt neurosurgical care are at risk of a poor outcome.9 For example, acute subdural hematomas in patients with severe TBI are associated with a 90% mortal­ ity if evacuated more than 4 hours after injury, but only 30% mortality if evacuated earlier. 2 9'3° Consequently, it is recom­ mended that field Emergency Medical Services (EMS) systems operate under strict ground and aeromedical trauma transport protocols. Commonly accepted criteria for transport of head injured patients to a trauma center include severity of injury, a respiratory rate < 1 0, systolic blood pressure < 90 mm Hg, and a GCS score < 1 2 .

EMERG E N CY DEPARTM ENT MANAGEM ENT The ambulance arrived at the emergency department (ED) after a 1 5-minute transport. While the patient was being transferred onto the gurney in the trauma bay, it was noted that he was obese (5' 8" [ 1 72 em] , 275 lb [ 1 2 5 kg] , BMI 42. 3 kg·m - 2) ; he had blood coming out of his right ear, and his cervical collar was riding high around his short neck. His BP was now 1 30/80 mm Hg, HR 1 1 0 bpm, RR 24 breaths per minute, Sp0 was 2 90% on a non-rebreathing face mask, and he had snoring res­ pirations. His blood sugar was 1 1 0 mg/dL (6. 1 mmol· L- 1 ) . His GCS score had decreased to 6 (2 for opened eyes to pain only, 2 for moans, and 2 for intermittent decerebrate posturing) . At this point, it was noted that his right pupil was 8 mm and unre­ active; his left pupil was 4 mm and reacted sluggishly. A quick airway evaluation revealed that his teeth were still clenched; he had a 6-cm thyromental span and 4-cm hyothyroid distance. There was no evidence of blunt trauma to the neck, and the cri­ cothyroid membrane was identifiable and palpable in the mid­ line. Two large-bore IVs were secured, blood was drawn and sent for chemistries and type and cross match. The hemato­ crit on the venous blood gas was 4 5 . Portable chest and pelvis radiographs in the trauma bay were normal. Cross-table lat­ eral x-ray of the C-spine showed good alignment and no

Ai rway M a n a g e m e n t of a Patient with TBI

pre-vertebral soft tissue swelling. A focused assessment with sonography in trauma (FAST) examination of the abdominal was performed, which showed no free fluid in the abdomen. A stat neurosurgery consult was ordered. Personnel from diag­ nostic imaging called, saying that they were ready to image the patient once he was stabilized. While the trauma team was deciding the best approach to securing the airway and manag­ ing the suspected increased ICP, the patient had a 30-second tonic-clonic seizure and desaturated to an Sp0 of SOo/o. 2

oxygenation; (2) avoiding decreases in cerebral perfusion pres­ sure (CPP) ; and (3) minimizing movement of the head and neck. Attention must also be directed toward prevention of gas­ tric content aspiration during the process.

• What Elements of Airway Management

Elevated ICP is associated with worse outcomes in TBI. While its early recognition and management have not been conclu­ sively linked to improved outcome, it is prudent to avoid any further increases in ICP in the brain-inj ured patient. ICP reflects the state of the contents of the fixed housing of the intracranial vault. The three normal contents of the vault are brain tissue, cerebrospinal fluid (CSF), and blood. Intracranial blood volume is directly related to CBF. This flow is normally kept relatively constant over a wide range of blood pressures by cerebral autoregulation; as blood pressure varies, cerebral vasoconstriction or vasodilatation occurs to maintain constant blood flow, and in turn volume. However, the brain's ability to autoregulate blood flow over a range of blood pres­ sures is impaired or lost in TBI. A second mediator of CBF is blood carbon dioxide tension. As blood carbon dioxide tension rises, so will CBF, leading to increased intracranial blood volume and thereby increased ICP. While aggressive hyperventilation in the patient with TBI is no longer recommended in the absence of signs of brain hernia­ tion,9·35 attention should be paid throughout the airway man­ agement process to maintaining normocarbia. 13 CPP is the driving force for blood flow to the brain, and is measured by the difference between the mean arterial blood pressure (MAP) and the ICP, so that CPP = MAP - ICP. In the patient with disrupted autoregulation, decreases in MAP will decrease CPP while increases in MAP, if not accompanied by equivalent increases in ICP, may be beneficial because of the increase in driving pressure for oxygenation of brain tissue. It is generally recommended that the ICP be maintained below 20 mm Hg, MAP between 1 00 and 1 1 0 mm Hg, 35 and CPP at or above 70 mm Hg. Hypotension leading to a decrease in CPP, even for a very brief period, is especially harmful, and as already mentioned has been shown to be an independent predictor of increased mortality and morbidity in patients with a TBI.8·9

Must be Considered in This Patient?

The immediate priority in this patient is reoxygenation, given the evidence suggesting a worsening of prognosis with hypox­ emia in the patient with TBI.8•9 The patient should receive assisted face-mask-ventilation (FMV) with 1 OOo/o 0 • Once the 2 Sp0 is again well above 90%, attention can be turned to 2 formulating a plan for tracheal intubation. Unless the seizure spontaneously terminates within 1 to 2 minutes, pharmaco­ logic intervention with lorazepam would be indicated. From the perspective of airway management, trauma patients secured on a backboard with cervical immobiliza­ tion can appear intimidating. Notwithstanding, formal airway assessment may point to little anticipated difficulty (see sec­ tions "Difficult BMV: MOANS," "Difficult DL Intubation: LEMON," "Difficult VL Intubation: CRANE," "Difficult Use of an EGD: RODS," and "Difficult Cricothyrotomy: SHORT" in Chapter 1 ) . In this case, the patient's obesity pre­ dicts an increased likelihood of difficult FMV.31-33 DL may be difficult due to the patient's short neck and the C-spine immobilization: manual in-line neck stabilization (MILNS) increases the likelihood of obtaining a poor (e.g. , Cormack/ Lehane [C-L] Grade 3) view during direct laryngoscopy.34 Any trismus will likely resolve with muscle relaxant administration, if used. Extraglottic device (EGD) insertion may be difficult, but should succeed once pharmacologic paralysis is achieved. Finally, although obesity can make transtracheal access dif­ ficult, in this patient, the cricothyroid membrane was easily palpable, suggesting easy access. • How Are You Going to Proceed with

Tracheal I ntubation?

With a reasonable expectation of successful direct laryngoscopic intubation and the availability of a backup plan "B" (e.g., indirect videolatyngoscopy, FMY, EGD use, or cricothyrotomy) should intubation fail, RSI should be used in this uncooperative patient. This plan confers the advantages of optimal intubating conditions with skeletal muscle relaxation while helping to mitigate any laryngoscopy and intubation-induced increases in ICP through the use of narcotic and sedative-hypnotic induction medications. • What Are You r Goals During Tracheal

I ntubation of the TBI Patient with C-Spine Precautions?

Our goals are to achieve tracheal intubation expeditiously while avoiding secondary neurologic injury by ( 1 ) maintaining

• How Are CPP, ICP, Cerebra l Blood Flow (CBF),

and Autoreg u lation Related; What Changes Occur in TBI and How Ca n We Mod ify These Changes?

• How Does Ai rway Management

Affect ICP Dynam ics?

Laryngoscopy and intubation may cause an increase in ICP indirectly through an increase in blood pressure (with dis­ rupted autoregulation) or through a direct effect on ICP. Both laryngoscopy and placement of an endotracheal tube (ETT) result in afferent discharges that increase sympathetic activity and release of catecholamines, that is, the reflex sympathetic response to laryngoscopy (RSRL) . A catecholamine surge may occur, especially with multiple attempts at laryngoscopy, poten­ tially leading to increased heart rate and blood pressure. In the patient with TBI who has impaired autoregulation, such a

289

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blood pressure surge may contribute to an increase in ICP. This fact underscores the importance of using drugs such as sedative­ hypnotics and opioids to mitigate the RSRL. • What Effects on ICP Can be Expected from

Medications Commonly Used During Airway Management in the ED?

Pharmacologic agents used to aid in airway management must be selected with consideration of their effects on CPP. Prior to intu­ bation, a modest fluid bolus will help maintain blood pressure, while vasopressors such as ephedrine or phenylephrine should also be immediately available to treat post-intubation hypotension. Pretreatment, induction, and paralytic agents used to attenuate a rise in ICP and/or facilitate intubation in the patient with TBI have been discussed in detail in Chapter 4. It should be noted that if a longer-acting muscle relaxant is used to facilitate tracheal intu­ bation or maintain post-intubation paralysis, formal monitoring for further seizure activity should be instituted in this patient.

• What Effects Do Airway Open ing

Maneuvers and FMV Have on Movement of a Normal C-Spine?

Several radiographic studies have looked at the effects of air­ way opening maneuvers and FMV on C-spine movement. One cadaver study performed with no applied MILNS found that chin lift and jaw thrust caused as much extension at C 1 -C2 as oral laryngoscopic intubation.54 A second cadaver study, using backboard, cervical collar, and tape found that signifi­ cantly more C-spine displacement occurred with FMV than with either oral or nasal tracheal intubation. 55 However, a sub­ sequent study using elective surgical subjects with their heads taped in a neutral position found FMV to cause significantly less C-spine movement than DL at each of the occiput-C 1 , C 1 -C2, C2-C5, and C5-T 1 motion segments.44 Although sometimes conflicting in their results, these studies can at least be taken as an indication that appropriate C-spine precautions should be applied during all phases of airway management in patients at risk of C-spine injury.

C - SPI N E CON S I D E RATIONS Victims o f major trauma often require several interventions, including definitive airway control, before a full assessment of the C-spine is possible. Without radiographic evidence of an intact C-spine, an unstable injury should be assumed and air­ way management undertaken accordingly. • What Ra nge of C-Spine Movement Is

Considered Within Physiologic Lim its?

In order to interpret the data on the effects of airway manipu­ lations on movement of the C-spine, the amount of motion that would indicate spinal instability should be defined. Panjabi et al. have suggested that horizontal motion (anteroposterior [A-P] displacement) of one vertebral body on another exceeding 20% of vertebral body width (or 3 . 5 mm in an adult, corrected for x-ray magnification) ; > 1 1 degrees of relative angulation of adjacent cervical vertebrae, or > 1 .4 mm of distraction on rest­ ing lateral radiography of the sub-axial C-spine is abnormal and would indicate instability. 3G-} S Preexisting cervical abnormalities such as spinal stenosis could increase the risk of neurologic con­ sequences inside these "anatomic limits."39 • What Effect Does DL and I ntu bation Have on

Movement of the Normal C-Spine?

Radiographic studies on live and cadaveric subjects with intact C-spines demonstrate that DL causes considerable extension berween the occiput and C2. Most extension (about 1 2 degrees) occurs berween the occiput and C 1 , with about half as much (approximately 7 degrees) berween C1 and C2.40-51 A total of about 6 degrees of extension occurs from C2 to C5.41-44•50•51 From C5 to the cervicothoracic junction, a small amount (about 8 degrees) of flexion occursY-44 Actual tube passage causes slight additional superior rotation berween the occiput and Cl, but little other movement.4050 There is some evidence that expos­ ing only a "minimum view" during laryngoscopy (i.e., seeking a view of only the posterior elements of the laryngeal inlet, but not of the cords) will reduce occiput-C2 extension.40•50•5 2 •53

• What Are the Effects of Ai rway Open ing

Maneuvers and FMV in Models of an I nju red C-Spine?

Donaldson et aJ.54 studied the motion occurring during various airway maneuvers in a series of six cadavers with a surgically created unstable C 1 -C2 segment. With the head stabilized, they found that pre-intubation maneuvers (chin lift and jaw thrust) caused more narrowing of the space available for the spinal cord (SAC) than DL or blind nasal intubation. In a subsequent cadaver series, this time with an unstable C5-C6, the same investigators demonstrated a trend toward chin lift/ jaw thrust causing as much movement as DL.56 Aprahamian et al.57 also studied a cadaveric specimen with a posteriorly desta­ bilized C5-C6 segment, and similarly reported that chin lift/ jaw thrust caused as much or more movement at the site of injury as oral or nasal intubation. Brimacombe et aJ.58 deter­ mined C-spine motion for six airway management techniques in cadavers with a posteriorly destabilized third cervical (C3) vertebra. Here again, both chin lift/jaw thrust and oral intu­ bation with DL caused significant antero-posterior (A-P) dis­ placement of the unstable segment, although the movements were within the previously described physiologic limits. Finally, Pasarn et al. studied nine lightly embalmed human cadavers with a surgically created unstable C 1 -C2 injury, comparing the motion caused by a jaw thrust maneuver with that resulting from a head tilt/chin lift. Using electromagnetic motion sensors attached directly to the spine above and below the injury level, they found that head tilt/chin lift caused significantly more angular motion in all planes, and more axial displacement and A-P translation than the jaw thrust maneuver.43•59•60 • How Effective Is MI LNS in Preventing

C-Spine Motion in Normal Patients and I nju ry Models?

MILNS appears to restrain overall spinal movements occurring during DL in patients and cadaveric specimens with normal

Ai rway M a n a g e m e n t of a Patient with TBI

spines to within physiological levels, and has less impact on air­ way interventions than do other forms of immobilization.41·53·61 In inj ury models, Lennarson et al.5 o .G2 reported that MILNS did not completely eliminate movement at the inj ury level during intubation of a cadaver model with either posterior or complete ligamentous C4-C5 disruption; however, the move­ ments recorded during interventions were within physiological limits. Gerling evaluated the effect of MILNS as well as cervi­ cal collar immobilization on spinal movement during DL in a cadaver model with a C5-C6 transection injury. Although there was less A-P displacement measured with application of MILNS compared with collar (7. 5% of vertebral body width vs. 1 3 .7%) , the overall magnitude of movement was small and within physiological range. There was no difference in axial distraction or angular rotation. 63 Turner studied 1 0 cadavers surgically destabilized at C4-C5. MILNS did not significantly change the median motion seen during DL in any of angula­ tion, distraction, or A-P displacement at the unstable leveJ.39 Two recent comprehensive reviews on the topic support the notion that while there may be some reduction in over­ all C-spine motion with MILNS , movement at individual motion segments, including sites of injury, may in fact not be significantly restrained by stabilization. 28'64 As Aprahamian et al.57 stated about collar immobilization in 1 984, it may be that MILNS should simply be taken as a cautionary sign of a pos­ sible neck injury, and to then use gentle and precise airway maneuvers to minimize C-spine movement.64

• How Does Appl ied M I LNS I m pact DL?

Many trauma patients presenting to the ED arrive on a back­ board immobilized with rigid cervical collar, sands, and tape. Unfortunately, any immobilization technique that restricts mouth opening will make laryngoscopy more difficult. In one study, 64% of patients immobilized with a collar, tape, and sandbags presented at Grade 3 or 4 view with DL, compared to only 22o/o of patients undergoing MILNS , with cervical collar removed.34 Other studies concur that DL in patients stabilized with cervical collars will result in a > 50% incidence of C-L Grade 3 or 4 views.63·65 Goutcher and Lochhead66 stud­ ied the effect of semirigid cervical collars on mouth opening in awake volunteers. Mean mouth opening of 40 mm without a collar decreased to 26 to 29 mm with cervical collar, and in a quarter of the subjects, mouth opening was reduced to 20 mm or less. A common pattern of practice is therefore to loosen or open the rigid collar (i.e., removing the anterior ele­ ment) during laryngoscopy after the application of MILNS . In general, when MILNS is substituted for a rigid cervical collar, the direct laryngoscopic view should improve, with a quoted incidence of C-L Grade 3 or 4 views improved to berween 20%5 1 ·67-69 and 50o/o.70-7 2 1hiboutot randomized elective surgi­ cal patients to standard "sniffing" position or MILNS for DL. In this series, the incidence of C-L Grade 3 or 4 view in the MILNS group exceeded 50% versus 5o/o for the unrestricted, sniffing position, and 50% of MILNS patients could not be intubated on the first attempt, compared to 5 . 7% without MILNS .70 The consistent message from the literature is that MILNS application is associated with difficult DL; strategies

to improve laryngeal view (e.g. , use of indirect video laryn­ goscopy) and facilitate tracheal intubation during the appli­ cation of MILNS have been reported and will be discussed subsequently. • Why Is Traction No Longer

Used During MI LNS?

Older publications make reference to using in-line traction when C-spine precautions were indicated. However, traction forces applied during MILNS may endanger the spinal cord if there is a serious ligamentous injury. Lennarson et al. 62 noted distraction at the site of a complete ligamentous injury when traction forces were applied for the purposes of spinal stabiliza­ tion during DL. Similarly, Kaufman et aJ.l3 demonstrated that in-line traction applied during radiographic evaluation resulted in spinal column lengthening and distraction at the site of injury in four recently deceased patients with ligamentous disruptions. Bivins et aJ.l4 also studied the effect of in-line traction during oro tracheal intubation in four victims of blunt traumatic arrest who had unstable spinal injuries. Traction applied to reduce sub­ luxation at the site of injury resulted in both distraction and posterior displacement at the fracture site. Current recommen­ dations promote the use of in-line stabilization and not traction during airway interventions requiring C-spine precautions. • Does the Choice of Di rect La ryngoscope

Blade I mpact the Degree of C-Spine Movement During Laryngoscopy?

Several investigators have studied C-spine movement caused by different DL blades. Two studies in elective surgical patients found significantly less (by about three degrees) head exten­ sion with Miller, as compared with Macintosh blade laryngos­ copy.46·75 However, other studies have failed to demonstrate a difference in motion berween the rwo blades.55·61·76 Studies with the levering tip McCoy/CLM-type blades have also generated conflicting results: some have found significantly less C-spine movement with use of the activated blade when compared to a Macintosh5 2·77 while others have not. 63·78 In cadaver injury models, one study showed that Miller blade laryngoscopy resulted in significantly less axial distraction ( 1 -2 mm) at the level of a surgically created C5-C6 transection than the Macintosh, but no difference in angular rotation or A-P displacement.63 However, Aprahamian et al.'s57 study of a single cadaver, also with an unstable C5-C6 injury, reported no differ­ ence berween Macintosh and Miller blades. At present, there is no evidence that Miller blade use is preferred to the Macintosh for DL when attempting to minimize movement of the C-spine.79 • Is Any DL Blade Superior for Exposing the

Glottis with Appl ied MI LNS?

To date, there is no convincing evidence that either curved or straight blades are superior to the other for exposing the laryn­ geal inlet during DL with applied MILNS. However, a num­ ber of studies suggest that laryngoscopy using the levering tip McCoy/CLM blade with the tip activated may be helpful when a poor view is obtained in the setting of MILNS. Three studies

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of the McCoy blade report improvement of a C-L Grade 3 view to 2 or better in 83% (with applied MILNS)80; 86% (MILNS with cricoid pressure)8 1 ; and 92% (rigid cervical collar) of cases respectively,8 2 compared with Macintosh blade DL. • How Do Alternatives to DL Such as Indirect

Video-La ryngoscopes I m pact C-Spine Movement During Tracheal I ntu bation?

Many of the alternatives to DL, such as indirect optical- or video-laryngoscopes appear to cause somewhat less movement of the C-spine during tracheal intubation. Laryngoscopy and intubation with the Bullard laryngoscope has been shown to result in significantly less C-spine movement than DL with Macintosh41•76•83 or Miller blades.76 Similarly, intubation with the Pentax Airway Scope (AWS) results in significantly less upper C-spine movement than DL with both attempted full48·84 and minimal view85 exposure of the cords. C-spine movement dur­ ing AWS use is further reduced with passage of a tracheal tube introducer (TTl) via the blade's delivery channel prior to ETT advancement.86 Compared with the Macintosh blade, Airtraq­ facilitated intubation appears to cause significantly less move­ ment at some, but not all43 ,45 of the studied C-spine motion segments. However, a more recent cadaver study using a surgi­ cally created unstable odontoid fracture failed to demonstrate a significant difference in space available for the spinal cord at the C 1 -C2 segment between Airtraq, Macintosh, and McCoy blade laryngoscopy and intubation. In this study, the DL blades were used to only expose a minimum (arytenoids) view, MILNS was applied, and a TTl was passed prior to the ETT.87 The use of a GlideScope video-laryngoscope (GVL) during MILNS resulted in some reduction in mid-cervical (C2-C5) spine movement compared with DL in one study44; another failed to show a significant difference in average spine move­ ment at any level to that occurring during DL.51 Studies with the Bonfils and Shikani optical stylets have concluded that less C-spine movement occurred with the optical stylets compared to Macintosh blade DL.44·83•88 Results with the LMA-Fastrach vary, with some studies showing small amounts of flexion of the upper C-spine during ILMA insertion and subsequent intubation with MILNS,89 while others have demonstrated extension, although not significantly different from that encountered during DL.90 Tracheal intubation using a flex­ ible bronchoscope (FB) results in less movement of the head and neck compared to DL,90 GVL,91 and LMA-Fastrach58faciliated intubation in anesthetized patients. However, this information must be tempered with the appreciation that FBs are expensive, more difficult to use, particularly in the pres­ ence of blood and secretions, and can be time-consuming in emergencies.4° FBs are generally used if an awake intubation is elected, an option that permits the advantage of post-intubation neurologic reassessment. To summarize, although studies have suggested that many of the foregoing devices result in less movement at some C-spine segments than DL, there is no evidence of a better neurological outcome with their use in the patient at risk with a C-spine injury. Indeed, as discussed in the next section, use of such alternatives to DL is probably most beneficial to maximize the

chances of laryngeal visualization and first-attempt intubation success with MILNS application during tracheal intubation. • How Do Adjuncts and Alternatives to DL

Such as Indirect Video-Laryngoscopes Compare for Successful I ntubation of the Patient U ndergoing MI LNS?

The TTl is a valuable adjunct to DL in the patient undergoing MILNS. Nolan and Wilson68 randomized half of 1 57 patients undergoing MILNS in the operating room to attempted primary passage of the tube, or prior passage of a TTL Although the pri­ mary technique was quicker on average, 1 1 patients in this group required >45 seconds for intubation, and there were five failures. All five failures were successfully intubated with adjunctive use of the TTL There were no failures in the TTl group. Studies of the Bullard laryngoscope,41•65•92 GVL, 69•92 •93 CMAC video-laryngoscope with use of the Macintosh blade,94 McGrath Series 5 video-laryngoscope,95 Pentax AWS,69•96-98 and Airtraq,99.102 or optical stylets71.103 have documented one or more of a significantly improved laryngeal visualization,69•70•100·101 better success rate,72'101 ' 104 or lower intubation difficulty score (IDSf0·100·101•103•105 compared to Macintosh blade DL in patient or cadaver studies during MILNS or use of a cervical collar. A study that compared the Pentax AWS with the GlideScope in a series of adult patients with MILNS reported more rapid intubation with the AWS . 1 06 One pediatric study comparing the GlideScope to DL (curved and straight blades were used) failed to demonstrate an improved view during MILNS. 1 07 Several series evaluating LMA-Fastrach use in patients with applied rigid collars have reported intubation success rates comparable to those obtained in unrestrained elective surgi­ cal patients108•109: the one study reporting a poor success rate under these conditions had included cricoid pressure in the study protocol . 1 1 0 I n general, most o f the alternatives t o DL, including video­ laryngoscopes used in the patient undergoing MILNS cause comparable or less neck movement and generally enable easier visualization and/or tracheal intubation. For those with access to the devices and skill in their use, they may be a good option for such conditions, although compared to DL there are no data indicating an outcome benefit. • Is Cricoid Pressu re Contraindicated in

Patients with Potential C-Spine I nju ry?

The reader is referred to Chapter 5 for a more detailed discus­ sion on the risks and benefits of cricoid pressure in emergency airway management. The authors' opinion is that cricoid pres­ sure may prevent aspiration in some patients, has low potential to do harm, and can readily be removed if its application results in difficulty in airway management; it generally may be applied when there is a concern that the risk of regurgitation and aspi­ ration is increased. With specific reference to the use of cricoid pressure in the patient with potential C-spine injury, radio­ graphic studies (albeit in cadaveric specimens) have generally found that C-spine movement with application of cricoid pres­ sure is within physiologic limits. In one study of six cadavers

Ai rway M a n a g e m e n t of a Patient with TBI

with intact C-spines, with 40N of applied cricoid pressure and using radiographs for assessment, Helliwell et al. 1 1 1 found a median A-P displacement of < 1 mm. In an earlier study of cadavers with a surgically created unstable C-spine at the C5-C6 level, Donaldson et aJ.56 reported a mean of 0 . 64 mm of A-P translation, 3 . 6 degrees of angulation, and 1 mm of spinous process distraction with cricoid pressure application. The decision to apply cricoid pressure in the patient with TBI must be considered in the context of both its potential for minor risk of C-spine movement and other detrimental effects. Cricoid pressure may interfere with FMV or efforts to place or ventilate through an EGD. 1 1 2 Difficulty with ventilation likely results from obstruction of the airway by the applied pressure; the loss of airway patency may also shorten the time to desat­ uration even in the absence of ventilation. 1 1 3 A recent review has suggested that cricoid pressure may also adversely impact airway management with DL, the lightwand, and the FB. 1 1 2 Thus, although cricoid pressure appears to result in radiographic movement that is within physiologic limits,36 it may be prudent to reconsider its use in patients with known unstable lesions at or near the level of the cricoid cartilage, or in those in whom dif­ ficulty with FMV or tracheal intubation has been encountered. • Does Admin istration of an Ind uction Agent

and/or a Muscle Relaxant by Itself Have Any Effect on the C-Spine?

Historically, concern has been raised that administration of an induction agent and muscle relaxant to the patient with a C-spine injury could release any "splinting" of an unstable segment by adjacent muscle spasm. However, there is no pub­ lished evidence for a clinically significant increase in the degree of cervical spinal movement due solely to induction agent and muscle relaxant administration. • Do EGOs Cause Significant C-Spine

Movement on Insertion?

In a cadaver study, both the LMA-Classic and LMA-Fastrach were found to transiently exert pressure on the upper cervi­ cal vertebrae during insertion, suggesting the potential to cause some degree of flexion in that location. 1 14 This was confirmed in a later in vivo study in which the LMA-Fastrach was found to cause an average of 1 .4 to 3 . 0 degrees of flexion of the upper C-spine during insertion and a lesser amount upon removal. 89 This contrasts with the extension caused by direct and video­ laryngoscopy. In a cadaver model of a destabilized C3 segment, both the LMA-Fastrach and LMA-Classic caused posterior dis­ placement of the unstable segment, yet significantly less than that caused by Combitube'" insertion.58 However, in all cases the movement was less than that deemed "physiologic" (see sec­ tion "What Range of Cervical Spine Movement Is Considered Within Physiologic Limits?" in this chapter) . Furthermore, EGOs are vital rescue oxygenation tools in difficult airway situ­ ations, with their benefits in reoxygenating a hypoxemic patient often outweighing any potential risk posed by small movements of the C-spine, particularly if care is taken to minimize such movement.

• How Does a Cervica l Collar or M I LNS

I nfl uence the Ease of Insertion of, or Ventilation Through EGOs? What About Tracheal I ntubation Through EGOs?

Clinical trials, many using a cross-over design have indicated that presence of a cervical collar or application of MILNS without a collar adversely impacts overall or first-attempt suc­ cess insertion rates with the LMA-Classic, 1 1 5 LMA-Fastrach, 104 Laryngeal Tube, 1 16 and Combitube. 1 17 Comparative studies have indicated a slight advantage to the LMA-Proseal 1 1 8 and the LMA-Fastrach1 19 when compared with the LMA-Classic under these conditions, and substantially better performance of the LMA-Fastrach when compared to the Laryngeal Tube. 1 20 Interestingly, in a study of the LMA-Supreme, once inserted, application of a cervical collar increased the effectiveness of seal pressure from a median of 22 to 27 em H 0 . 1 2 1 2 A small case series of 1 0 patients published in 2000 sug­ gested a poor success rate with blind intubation through the LMA-Fastrach while wearing a neck collar with applied cricoid pressure. 1 10 However, larger series published subsequently have reported that intubation success rates with blind104'1 22 or FB facilitated1 23 intubation through the LMA-Fastrach during cervical collar or MILNS application appear to be similar to standard conditions. • What Effect Does Cricothyrotomy Have on

C-Spine Movement?

Surgical cricothyrotomy was originally advocated as a preferred airway intervention in patients at risk for C-spine injury, rather than oro tracheal intubation, and is now deemed to be an appro­ priate alternative in an urgent situation if oral or nasal routes cannot be used or are unsuccessful. Although long considered safe in the presence of a C-spine injury, the effect on C-spine movement of surgical cricothyrotomy has not been extensively studied. Gerling et al. 1 24 studied C-spine movement during open surgical cricothyrotomy in a series of 1 3 cadavers with a complete C5-C6 transection. A-P displacement was limited to 6.3% of C5 body width (i. e., 1-2 mm of subluxation) , and axial distraction to < 1 mm across the C5-C6 injury during the procedure. Earlier, using a similar injury model in a single cadaver, Donaldson et aJ.56 reported that A-P displacement was limited to 0.9 mm during tracheotomy. As these movements are within physiological levels, values from both studies would likely be less than the threshold for clinical significance. • How Safe Is It to I ntu bate the Trachea of the

Patient with a Potential C-Spine I njury?

There is no evidence that tracheal intubation using careful direct or video-laryngoscopy with in-line stabilization results in secondary neurologic injury in patients with unstable C-spine fractures. 1 2 5 " 1 2 8 Traditionally, oral intubation using DL was deemed dangerous because it was thought to cause excessive spinal movement with the potential for secondary injury.67 It was thought that such secondary injury could be avoided by the careful performance of nasotracheal intubation or cricothy­ rotomy. Although there were no data at that time to support

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this thesis and later data would seem largely to refute it, this hypothesis had achieved a sufficiently widespread acceptance as to be labeled a "therapeutic legend of emergency medicine" by Rosen. 1 29 McLeod and Calder reviewed the use of the direct laryngoscope in patients with spinal injury or pathology. 130 With the possible exception of one case, 131 they concluded after review and analysis of the case reports that it was unlikely that the use of the direct laryngoscope was the cause of the myelopathies reported. As well, a report analyzing cases in the American Society of Anesthesiologists' Closed Claim data­ base echoed the view that most case reports ascribing cord injury to intubation in patients with unstable injury failed to provide sufficient data to support firm conclusions regarding causation . 1 28 In that analysis, 47 cases of cervical injury claims were identified in the database of 7740 claims filed between 1 970 and the end of 2007. In one instance, airway manage­ ment was j udged to be a probable contributor to cord injury in a C-spine surgery patient; in another it was j udged to be a probable contributor to injury in a patient who presented with an unstable injury but who did not have surgery. In both instances, the patients underwent difficult DL without cervical stabilization. The potential for aggressive DL with unrestricted spinal movement to cause neurological injury in spine-injured patients has also been detailed in two other reports. 131•13 2 However, the message that these reports emphasize is the need for spine stabilization in patients at risk of a C-spine injury until such injury is ruled out or definitive therapy for diagnosed C-spine inj ury is implemented, and not that careful direct or video-laryngoscopy is contraindicated. • Is DL Acceptable for I ntu bation of the

Patient with a C-Spine I njury?

There is clearly a difference of opinion in the literature regarding the optimal means of securing the airway by tracheal intubation in patients with C-spine injury. Many authors have reported on the use of the direct laryngoscope in the management of patients with C-spine injury for both elective and emergency intubations. 1 2 5-1 27•133-138 Most of these studies are limited both by their small sample size and their retrospective nature. However, they do reveal that neurological deterioration in spine-injured patients is uncommon after airway management when appropriate care is provided, even in high-risk patients undergoing urgent tracheal intubation. Reassuring as they are, these studies are not sufficient to rule out the possibility that on rare occasions, and even when provided with the utmost care, airway management undertaken in insolation or as part of a more complex clinical intervention, may result in neuro­ logical inj ury. The use of a direct laryngoscope following induction of anesthesia in the patient with a head inj ury is deemed an appro­ priate practice option by the American College of Surgeons as outlined in the manual of Advanced Trauma Life Support Program· (ATLS·, 2008) for doctors and by experts in trauma, anesthesia, and neurosurgery1 26'127•130·139' 148 and by the Eastern Association for the Surgery of Trauma. 149 Advantages of the direct laryngoscope in this setting include its effectiveness, the ability to visualize and remove upper airway foreign bodies

during use and clinician familiarity. These advantages have the potential to be augmented by the contemporary direct-style video-laryngoscopes-that is, those with Macintosh-shaped blades. Furthermore, indirect-type video-laryngoscopy blades may enable visualization of the larynx with less extension of the upper C-spine and will facilitate visualization during MILNS. Enthusiasm has been expressed by neuroanesthesia experts for the exclusive use of the FB to facilitate tracheal intubation in patients with a C-spine inj ury, citing this as the optimal prac­ tice option. 150 However, it is worth noting that over 40% of American anesthesiologists admit that they are not comfortable using an FB for airway management. 151 Further, it should be recognized that significant difficulties may be experienced dur­ ing the use of the bronchoscope, even by persons skilled in its use, during airway management in patients with a C-spine injury. 1 5 2 Carefully performed direct or video-laryngoscopy with appropriate MILNS in the trauma patient at risk for a C-spine injury can be considered a pattern of practice within the standard of care. • Is There Anything Else That Might Make

Ai rway Management More Difficult in the Patient with a C-Spine I njury?

A small number of case reports and case series document the association of pre-vertebral retropharyngeal hematomas with some injuries of the upper C-spine, particularly with a hyperex­ tension inj ury that disrupts the anterior elements of the spinal column.60•153-157 Such patients may present with symptoms of dysphagia and dyspnea, with the potential for difficult laryn­ goscopy due to anterior displacement of the laryngeal inlet. As well, patients with chronic spinal disorders, especially those resulting in abnormal ossification (e.g. , ankylosing spondylitis or diffuse idiopathic skeletal hyperostosis) may present with spine inj ury, including after relatively trivial trauma. Increased difficulties with tracheal intubation and high rates of medi­ cal and surgical complications resulting from care have been reported in such patient populations. 158•159

POST- I NTU BATION CON S I D E RATIONS • What Are the Post-I ntubation Considerations

in the Head-I nju red Patient?

Objective confirmation (e.g. , with an end-tidal C0 monitor) 2 of correct tracheal placement of the ETT is essential. Recognizing the importance of maintaining CPP, blood pressure should be reassessed after airway interventions and any unacceptable drop corrected with fluid and/or vasopressors. Pupils should be reassessed. After checking for optimal depth, the ETT should be firmly fixed to the patient, as many transfers will occur (e.g. , to the diagnostic imaging department and thereafter to the ICU or operating room) . However, tight ties encircling the neck should be avoided. If the patient's blood pressure per­ mits, a slight head-up position can be achieved by placing the stretcher in the reverse Trendelenburg position. This will pro­ mote venous drainage and may help reduce elevated ICP, if suspected.

Ai rway M a n a g e m e n t of a Patient with TBI

Mechanical ventilation in the patient with elevated ICP is based on optimizing oxygenation and avoiding ventilation mechanics (e.g., high levels of positive end-expiratory pressure [PEEP] or high peak inspiratory pressure [PIP] ) that would increase ICP. Controlled hyperventilation to a Paco of approximately 2 30 mm Hg was formerly recommended for the early manage­ ment of elevated ICP. It was believed that reduction in PaC0 2 tensions in the brain led to vasoconstriction and decreased cerebral blood volume, thereby decreasing ICP. However, a growing body of research provides evidence that routine hyper­ ventilation worsens outcomes in TBI patients, possibly due to alterations in regional CBF resulting in accumulations of neu­ rotoxic agents, for example, lactate and glutamate. 160 The Brain Trauma Foundation Guidelines for the Management of Severe TBI now recommends that prophylactic hyperventilation be avoided, and that patients with severe TBI be ventilated in such a way as to target not less than the lower limits of normocap­ nia (Paco of 3 5-40 mm Hg) . 13'161 A similar approach seems 2 prudent in patients with non-traumatic elevations of iCP (e.g., cerebral hemorrhage) . Hyperventilation to a PaC0 of 30 mm 2 Hg should be used only when osmotic agents and CSF drain­ age are not effective in managing an acute rise in ICP accom­ panied by patient deterioration, and utilized only until signs of herniation (e.g. , decerebrate posturing or a fixed, dilated pupil) resolve. Unless early and frequent neurological examinations are required (e.g., by a neurosurgeon to decide whether there is sufficient persisting neurological functioning to warrant an attempt at surgical evacuation of a massive subdural hema­ toma) , long-term sedation and paralysis will permit effective controlled mechanical ventilation and other necessary interven­ tions. Sedation and paralysis can also help mitigate the stimu­ lating effects of the tube in the trachea and will eliminate any possibility of the patient coughing or "bucking." If necessary, a full paralyzing dose of a competitive neuromuscular blocking agent, such as rocuronium 1 .0 mg·kg- 1 , may be given, along with the institution of a sedative infusion with a drug, such as propofol. The pharmacologically paralyzed patient at risk of seizures should be monitored with EEG.

ETT was passed over the introducer with the laryngoscope blade still in situ. Tracheal placement of the ETT was confirmed with visualization and a disposable end-tidal C0 detector, 2 whereupon cricoid pressure was released. The anterior aspect of the rigid cervical collar was reapplied, and MILNS was released. Vital signs were reassessed, with particular reference to the blood pressure. Continuous waveform capnography monitor­ ing was instituted to confirm normocarbia. Decisions were then made about ongoing sedation and skeletal muscle relaxation and arrangements were made for patient transfer to the diag­ nostic imaging department.

S U M MARY Airway management of the patient with a head injury must be undertaken with an appreciation of the importance of avoid­ ing secondary injury to both brain and C-spine. Hypoxemia and hypotension must be avoided and formal C-spine precau­ tions must be observed. However, apart from these directives, the practitioner should take comfort in the knowledge that as long as reasonable precautions are undertaken, familiar airway interventions are within the standard of care for the patient with potential C-spine injury, including RSI, bag-mask-venti­ lation, and tracheal intubation using carefully performed direct or video-laryngoscopy. To the practitioner experienced in their use, alternative intubation techniques (e.g., the FB alone or in combination with an EGD or video-laryngoscope) may be of value, although evidence is lacking on improved clinical out­ come compared to use of careful laryngoscopy with MILNS. Awake intubation of the patient with a known C-spine injury confers the opportuniry to reevaluate the patient's neurologic status post-intubation or even after positioning for surgery, before the induction of general anesthesia. Irrespective of tech­ nique chosen, airway management in this setting should not proceed before a formal airway evaluation has been performed, needed personnel have been assembled and briefed, and air­ way equipment for the chosen and "Plan B" approach has been readied.

REFERENCES • What Happened to Th is Patient? As outlined in the section "Emergency Department Management" in this chapter, the patient's airway was fully assessed. The deci­ sion was made to perform RSI. Preparations included ensur­ ing qualified help and requisite airway equipment were at hand, together with a briefing of the team about the "Plan B" approach should difficulty be encountered. An assistant was delegated to provide in-line immobilization of the C-spine, fol­ lowing which the front of the patient's rigid collar was removed. Denitrogenation was provided with a tightly fitting face mask and nasal prongs were applied with 1 0 Lmin- 1 of oxygen flow. RSI proceeded using fentanyl 1 00 flg, propofol 1 00 mg, and rocuronium 70 mg. For tracheal intubation, laryngoscopy was performed with a CMAC video-laryngoscope, using its Macintosh #4 blade, with the practitioner exposing only the posterior aspect of the laryngeal inlet. A TTl was then placed above the exposed arytenoid cartilages,68 following which the

1 . Winchell RJ, Hoyt DB. Endotracheal intubation in the field improves sur­ vival in patients with severe head injury. Trauma Research and Education Foundation of San Diego. Arch Surg. 1 997; 1 32 : 5 92-597. 2. Davis DP, Hoyt DB, Ochs M, et a!. The effect of paramedic rapid sequence intubation on outcome in patients with severe traumatic brain injury. ] Trauma. 2003;54:444-45 3 . 3 . Davis DP, Peay J, Serrano JA, e t a l . T h e impact of aeromedical response to patients with moderate to severe traumatic brain injury. Ann Emerg Med. 2005;46: 1 1 5 - 1 22. 4. Rajani RR, Ball CG, Montgomery SP, Wyrzykowski AD, Feliciano DV. Airway management for victims of penetrating trauma: analysis of 50,000 cases. Am ] Surg. 2009; 1 98 : 863-867. 5 . Cobas MA , De Ia Pena MA , Manning R, Candiotti K, Varon AJ. Prehospital incubations and mortality: a level I trauma center perspective. Anesth Ana/g. 2009; 1 09:489-493. 6. von Elm E, Schoettker P, Henzi I, Osterwalder J, Walder B . Pre-hospital tracheal intubation in patients with traumatic brain injury: systematic review of current evidence. Br J Anaesth. 2009; I 03:371 -386. 7. Bernard SA, Nguyen V, Cameron P, et a!. Prehospital rapid sequence intubation improves functional outcome for patients with severe traumatic brain injury: a randomized controlled trial. Ann Surg. 2 0 1 0;252: 959-965.

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Pre-Hospita l Ai rway M a n a g e m e n t 1 08 . Moller F, Andres AH, Langenstein H . Intubating laryngeal mask airway (ILMA) seems to be an ideal device for blind intubation in case of immo­ bile spine. Br j Anaesth. 2000;85 :493-49 5 . 1 09. Ferson DZ, Rosenblatt WH, Johansen MJ, Osborn I, Ovassapian A . Use of the intubating LMA-Fastrach in 254 patients with difficult-to-manage airways. Anesthesiology. 200 1 ; 9 5 : 1 1 75- 1 1 8 1 . 1 1 0. Wakeling HG, Nightingale J . The intubating laryngeal mask airway does not facilitate tracheal intubation in the presence of a neck collar in simu­ lated trauma. Br j Anaesth. 2000;84:254-256. 1 1 1 . Helliwell V, Gabbott DA. The effect of single-handed cricoid pressure on cervical spine movement after applying manual in-line stabilisation-a cadaver study. Resuscitation. 200 1 ;49: 5 3-57. 1 1 2. Neilipovitz DT, Crosby ET. No evidence for decreased incidence of aspiration after rapid sequence induction. Can J Anaesth. 2007;54: 748-764. 1 1 3 . Hardman JG, Wills JS, Aitkenhead AR. Factors determining the onset and course of hypoxemia during apnea: an investigation using physiologi­ cal modelling. Anesth Ana/g. 2000;90: 6 1 9-624. 1 1 4. Keller C, Brimacombe J, Keller K. Pressures exerted against the cervi­ cal vertebrae by the standard and intubating laryngeal mask airways: a randomized, controlled, cross-over study in fresh cadavers. Anesth Ana/g. 1 999;89: 1 296- 1 300. 1 1 5 . Gabbott DA, Sasada MP. Laryngeal mask airway insertion using cricoid pressure and manual in-line neck stabilisation. Anaesthesia. 1 99 5 ; 50:674-676. 1 1 6. Asai T, Marlin AG, Thompson J, Popat M, Shingu K. Ease of insertion of the laryngeal tube during manual-in-line neck stabilisation. Anaesthesia. 2004;59: 1 1 63 - 1 1 66. 1 1 7. Mercer MH, Gabbott DA. Insertion of the Combitube airway with the cervical spine immobilised in a rigid cervical collar. Anaesthesia. 1 998;53:971 -974. 1 1 8 . Asai T, Murao K, Shingu K. Efficacy of the ProSeal laryngeal mask airway during manual in-line stabilisation of the neck. Anaesthesia. 2002;57: 9 1 8-920. 1 1 9. Asai T, Wagle AU, Stacey M. Placement of the intubating laryngeal mask is easier than the laryngeal mask during manual in-line neck stabilization. Br J Anaesth. 1 999;82:7 1 2-714. 1 20. Komatsu R, Nagata 0, Kamata K, Yamagata K, Sessler DI, Ozaki M. Comparison of the intubating laryngeal mask airway and laryngeal tube placement during manual in-line stabilisation of the neck. Anaesthesia. 2005;60: 1 1 3 - 1 1 7 . 1 2 1 . Mann V, Spitzner T, Schwandner T, et a l . The effect of a cervical collar on the seal pressure of the LMA Supreme: a prospective, crossover trial. Anaesthesia. 20 1 2;67: 1 260- 1 265. 1 22. Nileshwar A, Thudamaladinne A. Comparison of intubating laryngeal mask airway and Bullard laryngoscope for oro-tracheal intubation in adult patients with simulated limitation of cervical movements. Br J Anaesth. 2007;99:292-296. 123. Mathew DG, Ramachandran R, Rewari V, Trikha A, Chandralekha. Endotracheal intubation with intubating laryngeal mask airway (ILMA), C-Trach, and Cobra PLA in simulated cervical spine injury patients: a comparative study. } Anesth. 201 4;28:655-66 1 . 1 24. Gerling MC, Davis D P, Hamilton RS, e t al. Effect o f surgical cricothy­ rotomy on the unstable cervical spine in a cadaver model of intubation. j Emerg Med. 200 1 ;20: 1 - 5 . 1 25 . Talucci RC, Shaikh KA , Schwab CW. Rapid sequence induction with oral endotracheal intubation in the multiply injured patient. Am Surg. 1 988;54: 1 8 5 - 1 87. 1 26. Shatney CH, Brunner RD, Nguyen TQ. The safery of orotracheal intuba­ tion in patients with unstable cervical spine fracture or high spinal cord inj ury. Am } Surg. 1 995; 1 70:676-679. 1 27. Suderman VS, Crosby ET, Lui A. Elective oral tracheal intubation in cervical spine-injured adults. Can } Anaesth. 1 99 1 ;38:785-789. 1 28 . Hindman BJ, Palecek JP, Posner KL, et al. Cervical spinal cord, root, and bony spine inj uries: a closed claims analysis. Anesthesiology. 20 1 1 ; 1 1 4:782-79 5 . 1 29. Rosen P, Wolfe RE. Therapeutic legends o f emergency medicine. J Emerg Med. 1 989;7:387-389. 1 30. McLeod AD, Calder I. Spinal cord injury and direct laryngoscopy-the legend lives on. Br jAnaesth. 2000;84:705-709. 1 3 1 . Hastings RH, Kelley SO. Neurologic deterioration associated with air­ way management in a cervical spine-injured patient. Anesthesiology. 1 993;78 : 5 80-583. 1 32. Liang BA, Cheng MA, Tempelhoff R Efforts at intubation: cervi­ cal injury in an emergency circumstance? J Clin Anesth. 1 999; 1 1 : 349-3 52.

1 33 . Meschino A, Devitt JH, Koch JP, Szalai JP, Schwartz ML. The safety of awake tracheal intubation in cervical spine inj ury. Can J Anaesth. 1 992;39: 1 1 4- 1 1 7. 1 34. Holley J, Jorden R. Airway management in patients with unstable cervical spine fractures. Ann Emerg Med. 1 989; 1 8 : 1 237- 1 239. 135. Rhee KJ, Green W, Holcroft JW, Mangili JA. Oral intubation in the multiply injured patient: the risk of exacerbating spinal cord damage. Ann Emerg Med. 1 990; 1 9: 5 1 1 -5 1 4. 1 36. Scannell G, Waxman K, Tominaga G, Barker S, Annas C. Orotracheal intubation in trauma patients with cervical fractures. Arch Surg. 1 993; 1 28: 903-905. 1 37. Wright SW, Robinson GG 2nd, Wright MB. Cervical spine injuries in blunt trauma patients requiring emergent endotracheal intubation. Am } Emerg Med. 1 992; 1 0: 1 04- 1 09. 1 38 . Norwood S, Myers MB, Butler TJ. The safery of emergency neuromus­ cular blockade and orotracheal intubation in the acutely injured trauma patient. } Am Col! Surg. 1 994; 1 79:646-652. 1 39. Richards CF, Mayberry JC. Initial management of the trauma patient. Crit Care Clin. 2004;20: 1 - 1 1 . 1 40. Ball PA. Critical care o f spinal cord inj ury. Spine. 200 1 ;26:S27-S30. 1 4 1 . Urdaneta F, Layon AJ. Respiratory complications in patients with trau­ matic cervical spine inj uries: case report and review of the literature. } Clin Anesth. 2003; 1 5 : 398-405 . 1 42. Ivy ME, Cohn S M . Addressing the myths of cervical spine injury management. Am } Emerg Med. 1 997; 1 5 : 5 9 1 -5 9 5 . 1 43 . Gajraj N M , Chason DP, Shearer VE. Cervical spine movement dur­ ing orotracheal intubation: comparison of the Belscope and Macintosh blades. Anaesthesia. 1 994;49:772-774. 1 44. Crosby ET. Tracheal intubation in the cervical spine-injured patient. Can } Anaesth. 1 992;39: 1 0 5 - 1 09. 1 4 5 . Abrams K, Grande C. Airway management of the trauma patient with cervical spine injury. Curr Opin Anaesthesia!. 1 994;7: 1 84- 1 90. 1 46. Hastings RH, Marks JD. Airway management for trauma patients with potential cervical spine injuries. Anesth Analg. 1 99 1 ;73:47 1 -482. 1 47. Dunham CM, Barraco RD, Clark DE, et al. Guidelines for emer­ gency tracheal intubation immediately after traumatic inj ury. } Trauma. 2003 ; 5 5 : 1 62- 1 79. 1 48 . Gajraj N, Pennant J, Giesecke A. Cervical spine trauma and airway man­ agement. Curr Opin Anaesthesiol. 1 993;6:369-374. 1 49. Mayglorhling J, Duane TM, Gibbs M, et al. Emergency tracheal intuba­ tion immediately following traumatic injury: an Eastern Association for the Surgery of Trauma practice management guideline. } Trauma Acute Care Surg. 20 1 2;73:S333-S340. 1 50. Chesnut RM. Management of brain and spine injuries. Crit Care Clin. 2004;20:25-5 5 . 1 5 1 . Ezri T, Szmuk P, Watters RD, Katz J, Hagberg CA. Difficult airway management practice patterns among anesthesiologists practicing in the United States: have we made any progress?} ClinAnesth. 2003; 1 5 :4 1 8-422. 1 52. McGuire G, el-Beheiry H . Complete upper airway obstruction during awake fibreoptic intubation in patients with unstable cervical spine frac­ tures. Can J Anaesth. 1 999;46: 1 76-1 78. 1 53 . Penning L. Prevertebral hematoma in cervical spine injury: incidence and etiologic significance. A}R Am J Roentgenol. 1 98 1 ; 1 36 : 5 53-56 1 . 1 54. Biby L, Santora AH . Prevertebral hematoma secondary to whiplash inj ury necessitating emergency intubation. Anesth Ana/g. 1 990;70: 1 1 2- 1 1 4. 1 5 5 . Shiratori T, Hara K, Ando N. Acute airway obstruction secondary to retropharyngeal hematoma. } Anesth. 2003; 1 7:46-48. 1 56. Myssiorek D, Shalmi C. Traumatic retropharyngeal hematoma. Arch Otolaryngol Head Neck Surg. 1 989; 1 1 5 : 1 1 3 0- 1 1 32. 1 57. Lin M, Sinclair C. Retropharyngeal haematoma-an unusual cause of airway obstruction. } Surg Case Rep. 20 1 1 ;20 1 1 : 5 . 1 5 8 . Thompson C, Moga R , Crosby ET. Failed videolaryngoscope intubation in a patient with diffuse idiopathic skeletal hyperostosis and spinal cord inj ury. Can } Anaesth. 2 0 1 0;57:679-682. 1 5 9. Bransford RJ, Koller H, Caron T, et al. Cervical spine trauma in diffuse idiopathic skeletal hyperostosis: injury characteristics and outcome with surgical treatment. Spine. 20 1 2;37: 1 923- 1 932. 1 60. Marion OW, Puccio A, Wisniewski SR, et al. Effect of hyperventilation on extracellular concentrations of glutamate, lactate, pyruvate, and local cerebral blood flow in patients with severe traumatic brain injury. Crit Care Med. 2002;30:26 1 9-262 5 . 1 6 1 . Brain Trauma Foundation, American Association of Neurological Surgeons, Congress of Neurological Surgeons, et al. Guidelines for the management of severe traumatic brain inj ury. VI . Indications for intra­ cranial pressure monitoring. } Neurotrauma. 2007;24 (suppl l ) :S37-S44.

Ai rway M a n a g e m e n t of a Patient with TBI

SELF-EVALUATION QU ESTIO N S 1 7 . 1 . Which o f the following i s contraindicated during intuba­ tion of the trauma patient undergoing C-spine precau­ tions with manual in-line neck stabilization (MILNS) ? A . removal o f the front o f the cervical collar B. oral intubation using direct laryngoscopy C. cricoid pressure D. external laryngeal manipulation E. none of the above 1 7.2. Which of the following airway interventions has been shown to improve neurologic outcome in the head­ injured patient with a potential cervical spine injury? A. performing an awake fiberoptic intubation B. performing manual in-line neck stabilization during intubation attempts C. use of an alternative to direct laryngoscopy, such as a GlideScope

D. avoiding transient oxygen desaturation E. all of the above 1 7 . 3 . Which of the following statements concerning the head­ injured patient is TRUE A. Improved neurological outcome is associated with the avoidance of direct laryngoscopy for intubation in this population. B. The unconscious head-inj ured patient (GCS < S) has a threefold chance of cervical spine injury. C. Avoidance of cervical spine movement during airway management is more important than avoiding tran­ sient hypoxia and hypotension. D. The safest way of performing tracheal intubation is proven to be the flexible bronchoscope. E. The use of muscle relaxants for intubation of these patients is contraindicated because they will interfere with subsequent neurological evaluation.

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Airway Management of an Unconscious Patient Who I s Trapped In side the Vehicle Following a Motor Vehicle Collision Arn im V/atten and Matthias Helm

CASE PRESE NTATION . . . . . . . . . . . . . . . . . . . . . . . . . . . 300 PATIENT CON S I D E RATI O N S . . . . . . . . . . . . . . . . . . . . .

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B-column on the driver's side of the car appeared to have struck the left side of the patient's head, and both lower extremities are trapped under the dashboard. Vital signs are stable and he is unresponsive to pain. He is breathing spontaneously with high-flow oxygen delivered via a non-rebreather face mask with a cervical spine collar applied and two large bore intra-venous cannulas placed in the antecubital fossae.

PATI ENT CON S I D E RATIONS • What Are the Considerations Extricating the

Patient from the Veh icle?

CASE PRESENTATION You are the emergency physician on duty for aeromedical trans­ port calls. You are called to the scene of a motor vehicle col­ lision in a remote area. Seventeen minutes into the flight, you hear from the on-scene paramedics that a young man hit a tree and flipped his car. He is the only occupant and is still trapped in the car. The rescuers have difficulry in extricating him from the vehicle. On landing, you see firefighters preparing to use a heavy-extrication tool ("Jaws of Life") . As you exit the helicop­ ter, the ground paramedic informs you that the accident scene is secure and that the patient is a 25-year-old obese man, uncon­ scious, with stable vital signs. As you approach the vehicle, you note major front-end damage to the car, encroaching on the vehicle's interior, the airbag deployed, and the patient appar­ endy unresponsive behind the steering column. The A- and

With organized traffic control and firefighters ensuring scene safety, a decision must be made about the urgency of extrica­ tion. A rapid extrication may be necessary in cases of impend­ ing arrest or uncontrollable bleeding. This strategy follows the rule "life before limb" and accepts the risk of further injuries to extremities and spine. A planned and deliberate rescue approach can be considered if there are no immediate life-threatening situations exist, such as a burning vehicle or markedly unstable vital signs. In the case of this patient, access to the patient had already been provided by the rescuers, permitting assessment of the patient by the emergency medical services (EMS) person­ nel and application of basic airway maneuvers and insertion of intravenous lines. Following the initial medical interventions, the rescuers would use a heavy-extrication tool to remove the roof of the vehicle and a hydraulic spreader to create space under the dashboard. The patient can then be extricated with full spine precautions.

Ai rway M a nagement of a n U n conscious Patient Fo l l owi n g a Motor Ve h i c l e Col l i s i o n

• What Are the Major Considerations

Accord ing to the Advanced Trauma Life Support (ATLS) Gu idelines?

According to the ATLS guidelines, the primary assessment of the patient addresses the airway, breathing of the patient, circulation, and disability (ABCD) . 1 After rescuer and patient safety, airway management has the highest priority. In this unconscious patient, the airway is in jeopardy and needs to be secured early. It must be assumed that the patient has suffered a severe traumatic brain injury. Oxygenation and ventilation are crucial steps in the initial management of the patient to avoid hypoxemia and hypercarbia, both of which worsen any brain injury. With such extensive vehicle damage, injuries other than to the brain, are very likely: cervical spine injury, pneu­ mothorax or flail chest, intra-abdominal injuries-all must be considered once the airway is assured. Due to the impacted legs under the dashboard, early extrica­ tion is unlikely. Since the patient's vital signs are stable and a rapid extrication may put a cervical spine injury at risk, a planned and careful extrication is preferable. Airway management must be performed while the patient is still inside the vehicle. • Are There Any Special Considerations

in Th is Case?

Special considerations in this case include urgent airway man­ agement in a difficult environment with limited patient access and resources. Access to a patient is usually gained by cutting the A- and B-column of the vehicle using the heavy-extrication tool and flipping the roof backwards, a procedure which may be time-consuming. In this case urgent airway management is necessary due to the traumatic brain injury with a resultant loss of airway reflexes. Tracheal intubation is still the gold standard in securing a patient's airway. However, a possible cervical spine injury as well as limited neck movement, and combined with limited access to the patient's head will certainly make airway management using direct laryngoscopy (DL) extremely difficult if not impossible. There is growing evidence to suggest that tracheal intubation under field conditions may be associated with no patient ben­ efit and may increase risk of adverse patient outcome. 2-4 Mort5 found a positive correlation berween complications and num­ ber of DL intubation attempts in the pre-hospital setting. Data from these studies suggest that there should be a limit to the number of intubation attempts or that DL be avoided in favor of alternative methods to secure the patient's airway. • How Would You Assess the Patient's Airway?

Signs of an airway at risk and inadequate breathing, such as sound of obstruction, gasping, indrawing, use of accessory mus­ cles, and cyanosis can be evaluated within seconds at the scene and must not be missed. Airway evaluation should include signs of airway trauma, neck trauma, and tracheal deviation. Several assessment tools can be used to assess a patient's airway and to predict difficulties (see Chapter 1 ) . However, these tools are of limited use in this pre-hospital setting of a trapped motor vehicle

collision victim due to limited patient access, unfavorable patient positioning, and poor patient cooperation. Given the patient's unconscious state, position, and the difficulty of access, it must be assumed airway management will be challenging.

AI RWAY MANAGEMENT • How Is the Airway Usual ly Managed in

Trauma?

Beyond clinical signs of airway patency and adequacy of breath­ ing, effective oxygenation and ventilation should be determined as quickly as practicable via pulse oximetry and end-tidal C0 2 measurement. 1 Oxygenation should be improved by high-flow oxygen via a non-rebreather face mask. All patients who are in acute respiratory distress or who are not breathing are in need of an immediate airway intervention. A rapid assessment of airway anatomy, appropriate to field conditions, must be done in case ventilatory assistance is required. While the mnemonic MOANS (see section "Difficult BMV: MOANS" in Chapter 1 ) may predict a difficult bag-mask-ventilation (BMV) , this assess­ ment tool is not useful for an unresponsive patient. If BMV is difficult in this unresponsive patient due to airway obstruction (e.g., a large tongue) , the obstruction can simply be relieved by lifting the chin or by the jaw-thrust maneuver, even though there may be a chance of aggravating C-spine injury. Similarly, the use of an oropharyngeal airway in the unconscious patient with no gag reflex or a nasopharyngeal airway in a patient with no facial or head trauma can be helpful in accomplishing a pat­ ent airway to facilitate BMV Patients with a Glasgow Coma Scale score of 8 or less require prompt tracheal intubation. Factors which may predict difficul­ ties with advanced airway maneuvers have to be identified. The mnemonic LEMON (see section "Difficult DL Intubation: LEMON" in Chapter 1) is helpful in predicting a difficult DL. However, its use in an unresponsive patient is limited. If no difficulties are anticipated, tracheal intubation with or without drug assistance should follow. If unsuccessful, adjuncts such as the Eschmann Tracheal Introducer (ETI, commonly known as "gum-elastic bougie"), extraglottic devices (EGDs) should be considered. In the case of inability to intubate the trachea and to ventilate the patient, a surgical airway should be established. 1 • What Are You r Airway Options

in Th is Patient?

Due to the critical condition of the patient with suspected cervi­ cal spine injury and the difficult working environment, airway management will be challenging. The options will depend on skills and level of training of the EMS practitioner. To avoid significant complications, advanced airway techniques should be attempted only by experienced EMS practitioners skilled in alternative methods of airway management. Practitioners with basic skills should rely on chin lift, jaw thrust, and tongue pull as basic airway maneuvers. However the risk of hypoxemia and hypercarbia has to be balanced against the risk of further aggra­ vating a spinal cord injury with jaw thrust maneuvers, should a

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simple chin lift is not sufficient to clear the obstructed airway. Basic airway maneuvers have to be performed with caution. In addition to the above-mentioned basic maneuvers, practitioners with advanced airway training should consider the placement of an EGO, such as a Laryngeal Mask Airway or Laryngeal Tube. The type of EGO used will be determined by the protocols of the EMS system. Experienced practitioners should at this point consider establishing a definitive airway using tracheal intuba­ tion. OL, video-laryngoscopy (VL) , intubating LMA, lightwand, or even cricothyrotomy may be used to provide oxygenation and ventilation. Each technique of airway management carries with it the risk of complications. These must be weighed against the risk of lethal hypoxemia coupled with the skills of the practi­ tioner in the adverse environment of the field. Complications of placement of a definitive airway are esophageal intubation, aspiration, and hypoxemia as a result of prolonged intubation attempts. Regardless of the practitioner's experience and level of training, the number of intubation attempts should be limited, as repeated attempts increase the risk of morbidity and mortality.5 • What Is the Role of the EGO in the

Trauma Patient?

EGOs are the first alternative in the cannot intubate, cannot oxygenate situation. They have gained popularity as the pri­ mary pre-hospital airway management of the trauma patient.6-9 Martin et al.8 reported a success rate of 94% in pre-hospital use of LMA in trauma patients with all insertions performed in 1 0 seconds or less. Adequate oxygenation and ventilation was provided with patient saturations ranging between 97% and 1 00% and end-tidal C0 between 24 and 35 mm Hg.8 2 Multiple second-generation laryngeal masks have been intro­ duced which incorporate an alternate channel for drainage of gastric contents and placement of a gastric tube. Second­ generation laryngeal masks (see Chapter 1 3) , for example, the LMA-Supreme, have even higher success rates in placement. Bosch et al. 1 0 and Linkimaki et al. 1 1 reported a successful place­ ment in 1 00% by ground paramedics in pre-hospital airway management. Laryngeal Tubes (see Chapter 1 3) have gained some popularity in pre-hospital airway management. However there are complications associated with the pre-hospital use of Laryngeal Tubes, such as significant tongue swelling, distention of the stomach, and significant bleeding due to malpositioning in the piriform sinus . 1 2 In summary, EGOs are effective rescue devices in trauma patients with a very high success rate for proper placement and providing effective oxygenation and ventilation. • What Is Your Concern with Tra nsporting

This Patient with an EGO?

Placement of an EGO is an efficient technique for airway man­ agement in the pre-hospital setting. However, two consider­ ations have to be kept in mind during transport of a patient with an EGO in place. First, the EGO does not provide complete protection against aspiration. Case reports and studies have reported gastric dis­ tention and aspiration with placement of an EGO similar to the

LMA or the Laryngeal Tube.8'1 2-14 Second-generation devices with a drainage tube at the distal end provide superior but not complete protection against aspiration.14 The second concern regarding the transport of a trauma patient with an EGO in place is potential malpositioning. Any change in the position of the EGO may impair or may block oxygenation and ventilation. A cervical collar to maintain inline stabilization of the cervical spine may cause the EGO to shift or to obstruct the airway during transport.9 Continuous monitor­ ing of position and effective ventilation must be provided. • What Are You r Options for a

Defin itive Airway?

The standard for a definitive airway still is endotracheal intuba­ tion with OL. 1 This requires the practitioner to be positioned above the head of the patient. In our case of a patient sitting in the driver seat positioning the airway practitioner above the head is impossible due to the restriction of space until the roof of the vehicle is removed. One alternative, the inverse intubation is a laryngoscopic approach from ventral directly facing the patient. This method is preformed using the standard laryngoscope in the right hand.15 The blade is used as a hook to allow a line-of-sight to the glottis. However significant anterior motion of the upper cervical spine may be necessary to achieve a line-of-sight to the glottic opening with potential for complications . 16 In recent years, multiple "look around the corner" devices as an alternative for OL have been introduced (see Chapter 1 1 ) . Th e McGrath Series 5 video-laryngoscope provides an indirect view of the glottic opening to allow the practitioner to face the patient from the front. Studies have shown that less movement of the cervical spine is produced during video-laryngoscopy com­ pared to standard OL. 17 The Airtraq, an optical laryngoscope using a series of lens and mirrors, provides not only an indirect view to the glottic opening, but also a guiding channel for the endotracheal tube. Both the Airtraq and McGrath Series 5 video­ laryngoscope were recently used in a study to compare their effec­ tiveness in a trapped trauma patient simulation. Both devices had a 1 00% success rate compared to 88% with inverse OL. The intubation time was 25 to 5 5 seconds for all three devices, and significantly longer compared to time for placement of EGOs . 17 An alternative approach for endotracheal intubation is to use the Intubating LMA (LMA-Fastrach'") as an adjunct. This is a blind technique. The endotracheal tube is advanced blindly through the metal tube of the LMA-Fasttrach'" into the trachea without visualization. In general, the position of the LMA­ Fastrach'" needs to be adjusted by rotating or lifting of the handle anteriorly to allow the endotracheal tube to pass easily through the vocal cords. This may increase the risk for cervical spine injury. In addition, this blind technique may also increase the risk for airway trauma. Overall the success rate for correct tube placement is in the range of 75% to 90% (see Chapter 1 3) . Another nonvisual technique for endotracheal intubation is the light-guided intubation using the lightwand (Trachlight'") . The technique of intubation is well described in Chapter 12. However, since this device is not manufactured anymore since 2009, the experience with the use of this device may diminish over time.

Ai rway M a nagement of a n U n conscious Patient Fo l l owi n g a Motor Ve h i c l e Col l i s i o n

A truly blind technique is the digital or tactile intubation. It is described in details in Chapter 1 2 . The middle and index fingers of the nondominant hand are inserted into the orophar­ ynx. The epiglottis is palpated and lifted anteriorly using the middle finger. Guided by the fingers of the nondominant hand, the endotracheal tube or an ETI can be inserted using the dom­ inant hand. Correct placement of the ETI can be confirmed by feeling the tracheal clicks and the hold up. The endotracheal tube will be advanced over the ETI into the trachea. Studies on digital intubation are rare. Stewart18 described the digital intu­ bation as a simple and useful technique in the pre-hospital set­ ting, with minimal head and neck movement being necessary. Blind nasotracheal intubation is a safe approach in the pre­ hospital field in spontaneously breathing patients. Even with low frequency of performance, the success rate is between 70% and 90%.19'20 However, the complication rate is reported as 1 3% . 1 9 Traumatic brain injuries with potential basal skull fractures and lack of respiratory efforts are contraindications for this technique. All nonvisual techniques, the lightwand guided, the digital, and blind nasal intubation require a certain skill set and should be restricted to practitioners with experience in those. If ventilation and oxygenation cannot be provided by either bag-valve-mask, an EGO, or endotracheal intubation, or a sur­ gical cricothyrotomy is indicated. 1 Surgical cricothyrotomy can be performed quickly and safely in the field by appropriately trained practitioners using the ETI-assisted three-step-technique (see Chapter 1 4) . • How Was the Ai rway Managed in Th is

Patient?

While you assess the overweight young patient trapped in the driver seat for any abdominal or thoracic injuries, you recog­ nize sounds of airway obstruction. Going back to your "A" for airway in patient assessment, you perform a gentle jaw thrust. While doing so, the patient is starting to clench down the teeth. The peripheral oxygen saturation probe is showing 90% on 1 00% 0 through a non-rebreather face mask. Since you 2 plan for a careful extrication with the rescuers, you decide to sedate the patient to allow for airway control. After intravenous administration of 5 mg midazolam and 1 00 mg ketamine, you can open the mouth of the patient easily and insert a #4 LMA­ Supreme'". With assisted spontaneous respiration, the oxygen saturation is increasing to 94% (Figure 1 8- 1 ) . After 1 0 minutes of technical rescue and extrication, the patient can be placed on a spine board and is transferred into the helicopter. Inside the helicopter, you reassess the patient following your "ABC" protocol. Due to the patient's obesity with an estimated weight of 95 kg and the position on the spine board, the abdominal girth is impairing ventilation via LMA and the oxygen satura­ tion drops to 90%. You decide to secure the airway with an endotracheal tube. However, he presents several features of a difficult laryngoscopy. In addition to his obesity, he has a small chin with a reduced thyromental distance, a large overbite, and a potential cervical spine inj ury. You prepare for a DL with an ETI ready. After administering 1 40 mg succinylcholine intrave­ nously, you perform a DL with a Mac#3 blade. You see nothing other than the tip of the epiglottis. One attempt with a blind

F I G U R E 1 8- 1 . An u n conscious patient sti l l tra p ped in the veh i cle. The roof of the ve h i c l e i s a l ready re moved by the s u rrou n d i n g fi refi g hters. T h e a i rway i s sec u red via a La ryn g e a l M a s k Ai rway. A s p i n e boa rd i s p l a ced o n ce the d river seat is l owered, a n d t h e patient w i l l be extricated fro m the ve h i c l e w i t h s p i n e preca utions.

insertion of the bougie fails. Your "plan B" was to reinsert the LMA-Supreme'". Quickly, the LMA-Supreme'" is placed and the patient ventilated and the oxygen saturation rises to 92%. In your mind, you take into consideration a suboptimal ventila­ tion of an overweight patient with a non-definitive airway on a long 3 5-minute flight to the nearest Level 1 trauma center and decide to perform a surgical (open) cricothyrotomy. After removal of the anterior part of the cervical collar, while still maintaining controlled ventilation via LMA-Supreme'M, you prepare the neck with an antiseptic solution and make a verti­ cal incision of the skin above the cricothyroid cartilage. You can easily palpate the cricothyroid membrane in the wound, make a horizontal incision through the membrane, and insert an ETI. Immediately you recognize correct placement by feel­ ing the clicks of the tracheal rings. Guided by the ETI, you can advance a 6.0-mm ID endotracheal tube. Correct tube place­ ment is confirmed by colorimetric C0 detector. The oxygen 2 saturation quickly improves to 96% on 1 00% Fi0 • 2

S U M MARY Airway management of an unconscious and apneic patient trapped in a vehicle is one of the most challenging situations for pre-hospital practitioners. Due to limited access above the head inside the vehicle, standard airway techniques are impossible

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and the patient's airway needs to be managed face to face. The technique employed will depend on the field environment, the patient's condition, available airway resources, and the technical skill of the practitioner. Following the ATLS guidelines, the focus should be on maintaining oxygenation and ventilation until there is access to the head or the patient is extricated from the vehicle. Basic airway techniques like chin lift, jaw thrust, and assisted bag­ valve-mask ventilation should be provided by every pre-hospital practitioner. With more advanced training, a more definitive airway can be achieved. This includes the use of an EGO and endotracheal intubation. However endotracheal intubation cannot be performed in the usual fashion and alternative tech­ niques, such as inverse intubation or digital intubation, should be considered. Alternative devices, such as video-laryngoscopes, can make intubation face to face easier. EGOs such as the Laryngeal Mask Airway or the Laryngeal Tube can easily be placed face to face and can act as a bridge until access to the patient is possible and a more definitive airway can be secured. The technique used will mostly depend on the skill of the prac­ titioner. As with all failed airway scenarios, surgical cricothy­ rotomy may be necessary in order to oxygenate and ventilate the patient in the vehicle.

14. Brimacomb ], Keller C. Aspiration of gastric contents during use of a ProSeal laryngeal mask airway secondary to unidentified foldover malposi­ tion. Anesth Analg. 2009;97: 1 1 92- 1 1 94. 15. Hilker T, Genzwuerker HV. Inverse intubation: an alternative for intuba­ tion in the streets. Prehosp Emerg Care. 1 999;3:74-76. 16. Smally AJ, Dufel S, Beckham ] . Inverse intubation: potential for complica­ tions. J Tra uma. 2002;52: 1 005- 1 007. 17. Schober P, Krage R, Van Groeningen D, Loer SA, Schwane LA. Inverse intubation in entrapped trauma casualties: a simulator based randomized cross-over comparison of direct, indirect and video laryngoscopy. Emerg Med}. 20 14;3 1 :959-963. 18. Stewart RD. Tactile orotracheal intubation. Ann Emerg Med. 1 984; 1 3 : 1 75 - 1 78 . 1 9. O'Brien GJ, Danzl DF, Hooker EA , Daniel LM, Dolan M C . Prehospital blind nasotracheal intubation by paramedics. Ann Emerg Med. 1 989; 1 8 : 6 1 2-6 1 7. 20. Weitzel N, Kendall ], Pons P. Blind nasotracheal intubation for patients with penetrating neck trauma. J Tra uma. 2004; 56: 1 097- 1 1 0 1 .

SELF-EVALUATION QU ESTIONS 1 8 . 1 . You are called t o a motor vehicle collision, where the driver is trapped inside the car. The patient is uncon­ scious and making ineffective respiratory efforts. How do you manage this patient? A. Extricate the patient as soon as possible. B. Insert a nasal airway to relief airway obstruction.

REFERENCES 1 . American College of Surgeons. Advanced Trauma Lift Support Program for Doctors: ATLS. Chicago, IL: American College of Surgeons; 2009. 2. Cobas MA, De la Pena MA, Manning R, Candiotti K, Varon AJ. Prehospital incubations and mortality: a level 1 trauma center perspective. Anesth Ana/g. 2009; 1 09:489-493. 3. Bochicchio GV, llahi 0, Joshi M, Bochicchio K, Scalea TM. Endotracheal intubation in the field does not improve outcome in trauma patients who present without an acutely lethal traumatic brain injury. } Trauma. 2003;54:307-3 1 1 . 4. Davis DP, Peay J, Sise MJ, et al. The impact of prehospital endotracheal intubation on outcome in moderate to severe traumatic brain injury. } Tra uma. 200 5 ; 5 8 : 933-939. 5 . Mort TC. Emergency tracheal intubation: complications associated with repeated laryngoscopy attempts. Anesth Analg. 2004;99:607-6 1 3 . 6. Greene MK, Roden R , Hinchley G. The laryngeal mask airway. Two cases of prehospital trauma care. Anaesthesia. 1 9 92;47:688-689. 7. Martin SE, Ochsner MG, Jarman RH, Agudelo WE. Laryngeal mask airway in air transport when intubation fails: case report. } Trauma. 1 9 97;42:333-336. 8. Martin SE, Ochsner MG, Jarman RH, Agudelo WE, Davis FE. Use of the laryngeal mask airway in air transport when intubation fails. J Tra uma. 1 999;47:352-357. 9. Matioc AA, Wells JA. The LMA-unique in a prehospital trauma patient: interaction with semirigid cervical collar: a case report. } Trauma. 2002;52: 1 62- 1 64. 10. Bosch J, de Nooji J, de Visser M, et al. Prehospital use in emergency patients of a laryngeal mask airway by ambulance paramedics is a safe and effective alternative for endotracheal intubation. Emerg Med }. 20 1 4;3 1 : 750-753. 1 1 . Lankimaki S, Alahuhta S , SilfVast T, Kurola J. Feasibility of LMA Supreme for airway management in unconscious patients by ALS paramedics. Scand } Trauma Resusc Emerg Med. 20 1 5 ;23:24. 12. Schalk R, Seeger FH, Mutlak H, et al. Complications associated with the prehospital use of laryngeal tubes-a systematic analysis of risk factors and strategies for prevention. Resuscitation. 20 1 4 ; 8 5 : 1 629- 1 632. 13. Mark DA. Protection from aspiration with the LMA-ProSeal after vomit­ ing: a case report. Can J Anesth. 2003; 50:78-80.

C. Intubate the patient using a rapid sequence induction to avoid aspiration. D. Following basic airway maneuvers to relief obstruc­ tion you attempt bag-mask-ventilation. E. Since you are facing an impending loss of airway, you attempt a surgical cricothyrotomy. 1 8 .2. Which of the following statements is INCORRECT? A. The risk of aspiration during ventilation with an EGO is low. B . EGOs are effective alternatives should endotracheal intubation fail. C. EGOs can be placed easily facing the patient from the front. D. EGOs can be used successfully with a steep learning curve in practitioners unfamiliar with advanced air­ way techniques. E. All EGOs are equally effective in the trauma population. 1 8 . 3 . Which of the following may make airway management difficult in the trapped patient? A. No access from above. B. Intraoral blood from head and neck injury. C. Suspected cervical spine injury. D. Acuity of the scene. E. All of the above.

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C H A PT E R 1 9

Airway Manage ment of a Race Car Driver with a Ful l - Face Helmet Fol lowin g a Crash Mark P. Vu, A ngelina Guzzo, and Orlando R. Hung

CAS E PRESENTATION

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D I F F I C U LT SITUATIONS: WHEN THE H E LM ET . . . . . . . . CAN NOT BE REMOVED . . . .

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S U M MARY .

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CASE PRESENTATION A 29-year-old male motorcyclist presents to the emergency department (ED) accompanied by a paramedic rescue team after being involved in a high-speed motor vehicle crash (MVC) . The motorcyclist was traveling at approximately 65 kilometers per hour (40 miles per hour) when he drove through an intersec­ tion and collided with a car. Although damage to the car was minimal, the motorcycle was severely damaged and the patient was found approximately 50 meters ( 1 60 feet) from the point of impact. The patient's vital signs at the scene were: HR 1 1 0 beats per minute (bpm) , BP 1 2 0/70 mm Hg, RR 24 breaths per minute, and Sp0 93% on room air. Paramedics placed the 2 patient on a spine board and transferred him to the ED. In the ED, he complains of pain in his chest, difficulty breathing, and pain in his legs. He is wearing a non-modular full-face helmet. His vital signs are found to be HR 1 2 0 bpm, BP 1 1 0/50 mm Hg, RR 32 breaths per minute, Sp0 89% and he is becoming 2 confused. There is clinical evidence of a compound fracture of his right femur.

PATI ENT CON S I D E RATIONS • What Are the I n itial Steps in the

Management of This Patient?

The general principles of trauma care and resuscitation apply to this patient. An initial, rapid survey of the patient's vital functions is undertaken including his airway, breathing, and circulation (the ABCs) . 1 Large-bore intravenous access, oxy­ gen, and basic monitoring (pulse oximetry, ECG, and serial blood pressure readings) are instituted quickly. Supplemental oxygen had been provided in the field by placing an inverted simple face mask through the opening of the helmet, an accept­ able maneuver if the helmet cannot be easily or safely removed for a primary survey. He is non-obese. His airway assessment shows that he is wearing a full-face, non-modular type motor­ cycle helmet, obscuring his mouth from view. His nose and nares are visible above the line of the face shield portion of the helmet, and his anterior neck is visible and displays normal anatomy. Rapid examination of his chest demonstrates equal air entry bilaterally and his pulses are equal. Although the patient is protecting his airway, he is breathing and has an adequate blood pressure. After completion of the primary survey he may require intervention to control his airway and breathing. • Are There Recommendations in the

Advanced Trauma Life Support® (ATLS®) G u ideli nes for the Removal of Helmets Prior to Transport?

There is currently no consensus regarding whether pre-hospital personnel should routinely remove a patient's helmet prior to transport to hospital. Individual patient factors and coexisting injuries will guide this decision. If possible, the helmet should remain in place unless emergency airway intervention or respi­ ratory support is needed, in which case the helmet should be

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carefully removed in a manner that minimizes cervical spine motion. Most helmet removal techniques endorse a two-person approach: one person stabilizes the patient's head from below while another person carefully removes the helmet from above. 2 New safety innovations in motor sports helmets include spe­ cialized helmet removal systems that facilitate the safe, careful removal of a helmet from a patient (e.g. , EQRS'", Shock Doctor Eject Helmet Removal System'") . Pre-hospital personnel should be encouraged to consult with a hospital-based EMS physician if questions regarding patient care exist. Airway practitioners who provide first responder care to motor sports athletes wear­ ing helmets should familiarize themselves with these specialized helmet release systems. • Are There Recommendations in the

ATLS® G u idelines for the Remova l of Helmets Once the Patient Has Arrived in Hospital ?

There i s also n o consensus on when or how a patient's helmet should be removed once the patient arrives in hospital. If the patient's condition is stable, the helmet can remain in place during the trauma assessment to minimize the potential for cervical spine movement. After a careful neurological assess­ ment, and if the patient is in stable condition, removal of the helmet under fluoroscopy may be considered. If the patient's condition necessitates emergency airway or breathing support, the risks of providing airway management with the helmet in place should be carefully weighed against the risks of emer­ gency removal of the helmet. These issues will be discussed later in this chapter. • Following a H ig h-Speed Motorcycle

Crash, What Other I nju ries Might You Anticipate for This Patient?

Anticipating and identifYing coexisting medical conditions in patients are important for practitioners . Alcohol is often a factor in motorcycle crashes and should be suspected in all cases .3 A prospective study in 1 996 involving 1 5 0 patients admitted to the emergency surgical service following an MVC showed that 37% were intoxicated with blood alcohol concentration (BAC) greater than or equal to 1 00 mg/dL4 or 0 . 1 o/o ( 1 o/o BAC by volume = 1 0 mg·mL - I , and the BAC legal limit is between 0 . 0 8 % and 0 . 1 o/o depending on the Province or State) . Other causes for the crash should also be considered, including cerebrovascular accident, cardiac event, seizure, or intoxication from substances other than alcohol. A focused survey of the patient as suggested by the ATLS® guidelines will help to identifY inj uries that will significantly affect airway management decisions . Airway practitioners should presume that this group of patients will have a full stomach and are at high risk for a cervical spine inj ury. In addition, patients with open-face helmets are at higher risk of sustaining facial inj uries, but these inj uries are still possible in patients wearing full-face helmets . A rigorous assessment of the oropharynx, nasal passages, and ears is often difficult

F I G U R E 1 9- 1 . Fu l l -face type h e l m ets prese nt a c h a l l e n g e to a i rway practitioners. The patient's mouth is com p l etely obscu red by the face sh ield portion of the h e l m et. I n genera l , the nose a n d neck a re rea d i l y acces s i b l e (rig ht). H owever, i n some types of fu l l -face h e l m ets, access to the nose may be l i m ited.

in patients wearing helmets and the benefits of a nasotra­ cheal approach to endotracheal intubation should be weighed against the risks of this procedure in this patient population.

AI RWAY CO N S I D E RATIONS • What Types of Hel mets Worn by

Motorcyclists Can Pose Problems for Airway Management?

Motorcycle helmets can be grouped into rwo categories in the context of airway management: open-face and full-face. Open­ face helmets cover the cranium, sometimes cover the ears, but do not cover the neck, chin, mouth, or nose. These features make them less protective to the patient in the event of a crash. There is an increase in the likelihood of serious anterior neck and facial injuries affecting airway anatomy, but concurrently renders airway assessment and intervention more straightfor­ ward. Full-face helmets are more protective to patient's face in the event of a crash, but are a major hindrance to airway assess­ ment and intervention since access to the mouth is practically impossible (Figure 1 9- 1 ) . Moreover, removal of full-face hel­ mets can be difficult, resulting in potentially significant cervi­ cal spine motion. 5·6 Laun et a!. conducted a study to evaluate the cervical spinal movement during the removal of a full-face helmet in 1 0 fresh cadavers with an experimental unstable frac­ tured odontoid. Under fluoroscopy, there was significant move­ ment of C 1 -2 during helmet removal and dislocation of C 1 -2 in rwo cases? Although the clinical significance of these find­ ings in live patients is unknown, this study suggests that there is a potential risk of spinal cord inj ury during the removal of a full-face helmet. An important variation on the full-face helmet is the "mod­ ular" full-face helmet (Figure 1 9-2) . The design of this helmet allows the movement of the face shield portion of the helmet

Ai rway M a n a g e m e n t of a Race Ca r Driver with a Fu l l -Face H e l m et Fo l l ow i n g a C ra s h

F I G U R E 1 9-2. M od u l a r-type h e l m ets a l low more optio n s for a i rway i nterve n t i o n s (l eft) . D i s p l a c e m e n t of the face s h i e l d ce p h a l a d (rig ht) a l l ows fu l l access t o the patient's nose, mouth, a n d n e c k a s we l l a s ventilation u s i n g a face m a s k.

away from the face. This helmet design allows the effective con­ version of a full-face helmet into an open-face configuration, making airway management with the helmet in place more feasible. • Should Helmets Always be Removed in

Order to Provide Ai rway Management?

Removal of helmets for airway management is case depen­ dent. There is currently no consensus on whether helmets should be routinely removed prior to airway management in trauma patients. There are concerns that cervical spine move­ ment during helmet removal may be significant. Although the evidence of cervical spine movement during helmet removal has been supported by radiographic studies in cadavers, its clinical importance remains unknown. In pre-hospital care, removal of helmets by paramedics is standard prior to airway management. However, in sports medicine it is sometimes rec­ ommended that emergency medical personnel have the tools to remove face shields in order to provide airway management with the helmet in place. 8 Some sports helmets brands now have "quick release" features that allow medical personnel to quickly and easily remove face masks to allow access to the airway without removing the helmet (e.g. , Riddell Speedflex Helmet, Riddelr") . Hospital-based airway practitioners should expect situations in which pre-hospital personnel have deferred definitive airway management until arrival at the hospital and therefore should be prepared for any scenario. • Describe a Systematic Approach to Manage

the Airway of a Patient Wearing a Motorcycle Helmet

Assessment of any patient wearing a motorcycle helmet should be completed in the standard fashion aiming to assess the fea­ sibility of providing oxygenation and ventilation by: ( 1 ) bag­ mask; (2) extraglottic device (EGO) ; (3) tracheal intubation by direct and indirect laryngoscopy; or (4) a surgical airway. The first part of the assessment of a patient wearing a motorcycle

helmet is identifYing whether the helmet is open-face or full­ face configuration. In a patient wearing an open-face helmet, airway man­ agement can be performed with the helmet in place and the patient's head can be manually stabilized by an assistant to min­ imize movement of the head and neck. Bag-mask-ventilation, EGO insertion, tracheal intubation, and surgical airway access are commonly straightforward in this scenario. If the open-face helmet has a visor, it can be removed to optimize line-of-sight during direct laryngoscopy. In a patient wearing a full-face helmet, the practitioner must now determine whether or not the helmet is a modular type. If it is a modular-type full-face helmet, the helmet may be left in place and the face shield portion can be carefully retracted superiorly to expose the face and neck. Once this is done, the airway can be managed with considerations similar to an open­ face style helmet. It should be noted that a retracted face shield might obscure the line-of-sight during direct laryngoscopy. Alternative orotracheal intubating devices such as a lightwand, a video-laryngoscope, or a rigid/flexible fiberoptic intubation device could be useful. In a patient wearing a full-face helmet that is not modu­ lar, several important issues must be carefully considered. Bag­ mask-ventilation and EGO insertion are practically impossible because access to the mouth and face is extremely limited by the face shield. Direct laryngoscopy is also impossible for the same reason. Access to the neck for a surgical airway is often possible and the anatomical landmarks for cricothyrotomy should be carefully assessed. At this juncture, the practitioner should decide: ( 1 ) Can the helmet be removed prior to airway management; and (2) Should the helmet be removed prior to airway management? In many cases, it may be most appropri­ ate to remove the helmet prior to airway interventions since this provides practitioners with the opportunity to properly assess the patient and optimally expose all relevant anatomy. Although there is no consensus on the proper technique for hel­ met removal, most authors advocate a two-person technique as described above. Helmets with specialized release mechanisms should be removed according to the manufacturer's instruc­ tions. These instructions can sometimes be found written on the sides of the helmet. Once the helmet is removed, oxygen­ ation and ventilation can be provided in the standard fashion. • Should the Endotracheal I ntubation be

Performed Awake?

In any patient wearing a motorcycle helmet, particularly a full­ face helmet, difficulties in airway management can be expected. Bag-mask-ventilation is impossible in patients wearing a full­ face helmet. Laryngoscopy is difficult or impossible with full­ face helmets, as is EGO insertion. In light of this, an awake intubation approach should be considered and is a reasonable option in cooperative patients. Unfortunately, awake intubation in this group of patients is challenging because they are often uncooperative and have significant secretions or blood in their airway, limiting the efficacy of topical anesthesia and visualiza­ tion. Practitioners must consider the challenges of an awake technique and be prepared to proceed to an alternative plan.

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D I F F I C U LT SITUATIONS: WH EN TH E H E LM ET CAN N OT BE REMOVED • Describe How You Would Provide

Oxygenation and Ventilation in a Situation Where You Cannot Remove a Non-Modular, Ful l-Face Helmet?

Arguably the most challenging situation for a practitioner is when a patient wearing a full-face helmet needs oxygenation and ventilation but the helmet cannot be easily removed. Many circumstances can make helmet removal difficult or impossi­ ble. Examples of such situations include patients with foreign objects penetrating the helmet and embedded in the skull and patients in whom removal of the helmet causes them extreme pain or distress, or individuals trapped in confined spaces where the helmet cannot be removed (e.g. , race car) . A systematic assessment of the airway management options for this patient will show that bag-mask-ventilation is impossible because the helmet's face shield obscures the mouth and chin. Similarly, insertion of an EGD is practically impossible because access to the mouth is also limited. The two remaining options are: (1) nasotracheal intubation or (2) surgical airway using a cricothy­ rotomy. Rapid assessment of the surgical landmarks relevant to cricothyrotomy, either percutaneous or open, is essential since this part of the patient's airway is usually unobstructed by the helmet or face shield. Securing the airway by a naso­ tracheal route is relatively simple and potentially useful and lifesaving. Airway practitioners familiar with nasotracheal intu­ bation techniques should review the contraindications to this approach, such as evidence of basal skull fracture, prior to pro­ ceeding. Blind nasal intubation in a spontaneously breathing patient has a reasonable success rate by experienced practitio­ ners. Two reports showed that blind nasal intubating technique has a 90% success rate for pre-hospital trauma patients requir­ ing an endotracheal rube (ETT) .9·10 However, the success of blind nasotracheal intubation is limited by practitioner skill. A flexible lightwand, such as the Trachlight'M, loaded on a naso­ tracheal rube can be effectively used to achieve endotracheal intubation in a patient wearing a full-face helmet. 1 1 In this technique, transtracheal illumination using the lighrwand indi­ rectly confirms proper placement of the nasotracheal rube. 1 2 If blood is present in the airway, the potential for a false passage in the airway makes a blind technique relatively contraindicated. Moreover, light-guided techniques may be difficult in pre­ hospital environments where bright ambient light may make identification of transtracheal illuminated landmarks difficult. Using a flexible bronchoscope can be a helpful guide, especially in situations where blind techniques are contraindicated, bur its efficacy may be limited by the presence of blood or secretions in the airway. Flexible endoscopic intubation can be performed with the patient awake and the nasopharyngeal mucosa topi­ cally anesthetized or with the patient under general anesthesia with muscle relaxation. The risks of each approach should be considered in the context of the patient's comorbidities and the practitioner's familiarity with the techniques. Airway practitioners are strongly advised to consider a "double setup" plan that includes both a primary intubation

approach (e.g., a light-guided nasotracheal intubation, flexible bronchoscope, etc.) and a secondary backup surgical approach for the patient wearing a full-face helmet that cannot be removed. Since the patient's neck is almost always accessible regardless of the type of helmet worn, a "double setup" facili­ tates prompt airway control via a surgical access in case the pri­ mary plan is unsuccessful. Two separate equipment trays should be prepared: the first contains all the equipment needed for oral or nasotracheal access; the second tray contains all the instru­ ments needed for a surgical airway. Having a second-skilled practitioner available who is familiar with surgical airway access is ideal. Prior to initiating the airway intervention, the patient should be optimally positioned, the neck should be prepped, and the airway management team should agree on clear "trig­ ger points" that identify when the primary approach has failed and the secondary approach is to be undertaken (i. e., surgical airway) .

• How Do You Perform a Lig ht-G u ided

Nasotracheal l ntubation for This Patient if It Becomes Necessary?

An appropriately sized uncut ETT should be used. While it is not possible to warm and soften the ETT in this emergency situation, generous lubrication of the ETT will facilitate nasal intubation and minimize injury. The Trachlight'M (or a flexible lighrwand) is prepared as previously described (see section "Can the Trachlight'M be Used for Nasotracheal Intubation? How Do You Use the TL to Perform a Nasotracheal Intubation?" in Chapter 1 2) with the stiff internal wire stylet removed so that the ETT/Trachlight'M (ETT/TL) unit is pliable and suitable for nasal intubation. Ideally, a vasoconstrictor, for example, xylo­ metazoline hydrochloride (Otrivin'M) nasal spray (if available and time permits) , should be administered prior to the inser­ tion of the ETT/TL through the nostril. Following the place­ ment of the ETT/TL tip into the nasopharynx, it is advanced gently into the glottic opening using the transillumination of the soft tissues of the anterior neck. As it is not possible to perform a jaw lift with the full-face helmet in place, a gentle jaw thrust with minimal neck movement can be performed by an assistant to elevate the tongue and epiglottis. Using the light glow, the tip of the ETT/TL is then guided to the glottic open­ ing. When the tip of the ETT enters the glottic opening, a bright circumscribed glow can be seen readily j ust below the thyroid prominence and the ETT/TL unit is then advanced into the trachea. The efficacy of Trachlight facilitated nasotracheal intubation in patients wearing motor cycle helmets was demonstrated in a study in patients under general anesthesia. 1 1 A BMW System IV motorcycle helmet was used to demonstrate feasibility of naso­ tracheal intubation with the face mask in the "down" position, and the modular design of the helmet also secondarily demon­ strated that bag mask oxygenation and ventilation was easy to perform with the face mask in the "up" position (Figure 1 9-2) . Transtracheal illumination was easily identified i n the operating room setting and mean intubation times were relatively rapid with no complications (Figure 1 9-3) .

Ai rway M a n a g e m e n t of a Race Ca r Driver with a Fu l l -Face H e l m et Fo l l ow i n g a C ra s h

F I G U R E 1 9-4. Th i s fig u re i l l u strates a "bougie-"g u ided open cricothyrotomy. F I G U R E 1 9-3. Lig ht-g uided n a sotra c h e a l i ntu batio n u s i n g a Trach l i g ht'M t h ro u g h a fu l l -face m od u l a r-type h e l m et (BMW System IV h e l m et). With a gentle jaw thrust, the ETI/TL was i n serted t h ro u g h the nostri l a n d i n to the n a s o p h a rynx. When the t i p entered the g l ottic open i ng, a bright c i rc u m scri bed g l ow (a rrow) was seen below the thyroid p ro m i n e nce.

• How Do You Perform an Emergency Surgical

Airway for This Patient if It Becomes Necessary?

In a scenario where the patient's helmet cannot be physically removed and emergency airway management is necessary, a surgical airway should be considered. There are multiple approaches to surgical airway access (see Chapters 14 and 1 5) . For non-surgeons o r airway practitioners not familiar with emergency open tracheostomy techniques, a recommended approach is the Tracheal Introducer ("bougie") facilitated open cricothyroidotomy. This approach combines the speed of the open criciothyroidotomy with the familiarity of the "bougie." The "bougie-"facilitated cricothyroidotomy requires the opera­ tor to use a scalpel to incise skin of the anterior neck in a lon­ gitudinal midline incision, palpate the cricoid cartilage with a gloved finger, breech the cricothyroid membrane with the scal­ pel, and pass a "bougie" into the trachea (Figure 1 9-4) . The cor­ rect endotracheal position of the "bougie" is confirmed by the familiar "clicks" of the coude tip of the "bougie" passing over the anterior tracheal cartilages. A simple and familiar Seldinger's technique is then employed to pass a tracheal tube over the "bougie" into the trachea. Emergency "bougie"-facilitated cri­ cothyroidotomy has gained the endorsement of many advanced airway management experts as well as emergency medicine organizations due to the simplicity of the procedure, the avail­ ability of the equipment used, and its effectiveness.13 • Would Your Approach to Airway

Management Change for a Patient Who Is Wearing a Footba ll Helmet or Hockey Helmet?

The approach to a patient who is wearing a different type of protective helmet is similar. Sports helmets can be open-face, full-face, and can have various styles of face shields. Many of these face shields can be easily removed with simple tools, such

as a screwdriver. For example, the cage of a football helmet can be easily removed using a cage removal tool that can instantly convert a caged and inaccessible airway into a manageable air­ way. Current recommendations suggest that injured athletes requiring emergency medical care should have their face shields removed and their helmets left in place for airway manage­ ment. 14•15 This highlights the fact that sports helmets have face shields or cages that are easily removed and recognizes research suggesting that cervical spine motion is lessened when the hel­ met is left in place.

S U M MARY Airway management in patients wearing a helmet can present a major challenge to airway practitioners. The principles of air­ way management remain the same regardless of whether or not the patient is wearing a helmet; however, the type of helmet can significantly impact the options available to practitioners. It is worth remembering that almost all patients wearing a hel­ met are trauma patients, and so the usual considerations of full stomach, head injury, and cervical spine precautions are appli­ cable. If a patient's airway can be managed with the helmet in place, this is often a safer option if an unstable cervical spine injury is suspected. Removing a helmet prior to airway manage­ ment is often appropriate to optimize intubating conditions, but should be done carefully. Rarely, situations occur where a patient's helmet cannot be removed but oxygenation and venti­ lation must be provided, and practitioners must have a plan and the skills to deal with this challenging situation.

REFERENCES 1 . American College of Surgeons: Committee o n Trauma. Advanced Trauma Lift Support (ATLS Student Course Manual). 9th ed. Chicago, IL: American College of Surgeons; 20 1 2 . 2. Tintinalli J E . Emergency Medicine, A Comprehensive Study Guide. 8th ed. New York, NY: McGraw Hill Professional Publishing; 20 1 5 . 3. Hurt H, Ouellet ], Thorn D. Motorcycle accident cause factors and identi­ fication of countermeasures. In: Technical Report, Traffic Saftty Center. Los Angeles, CA: University of Southern California; 1 98 1 . 4 . Mancino M , Cunningham MR, Davidson P, Fulton RL. Identification of the motor vehicle accident victim who abuses alcohol: an opportunity to reduce trauma. J StudAlcohol. 1 996;57:652-65 8 .

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Pre-Hospita l Ai rway M a n a g e m e n t 5 . Brimacombe J, Keller C, Kunze! KH, Gaber 0, Boehler M, Puhringer F. Cervical spine motion during airway management: a cinefluoroscopic study of the posteriorly destabilized third cervical vertebrae in human cadavers. Anesth Analg. 2000;9 1 : 1 274- 1 278. 6. Kolman JM, Hung OR, Beauprie IG et al. Evaluation of cervical spine movement during helmet removal. Can ] Anesth. 2003;50:A 1 8 . 7. Laun RA , Lignitz E , Haase N, Latta LL, Ekkernkamp A , Richter D. Mobility of unstable fractures of the odontoid during helmet removal. A biomechanical study. Unfollchirurg. 2002; 1 0 5 : 1 092- 1 096. 8. Waninger KN. On-field management of potential cervical spine injury in helmeted football players: leave the helmet on! Clin ] Sport Med. 1 998;8: 1 24- 1 2 9 . 9. Dauphinee K . Nasotracheal intubation. Emerg Med Clin North Am. 1 988;6:71 5-723 . 1 0 . Weitzel N, Kendall J, Pons P. Blind nasotracheal intubation for patients with penetrating neck trauma. J Trauma. 2004; 56: 1 097- 1 1 0 1 . 1 1 . Vu M, Guzzo A, Hung OR, e t al. A novel method for endotracheal intuba­ tion in patients wearing full-face helmets. World Congress ofAnesthesiologists. 2004;CD 0 1 4 . 1 2. Hung OR, Pytka S, Morris I, e t al. Clinical trial of a new lightwand device (Trachlight) to intubate the trachea. Anesthesiology. 1 995;83:509-5 1 4. 13. Frerk C, Mitchell VS, McNarry AF, et al. Difficult Airway Society 20 1 5 guidelines for management o f unanticipated difficult intubation i n adults. Br] Anaesth. 2 0 1 5 ; 1 1 5 : 827-848. 14. Laprade RF, Schnetzler KA, Broxterman RJ, Wentorf F, Gilbert TJ. Cervical spine alignment in the immobilized ice hockey player. A com­ puted tomographic analysis of the effects of helmet removal. Am J Sports Med. 2000;28 :800-803. 1 5 . Swenson TM, Lauerman WC, Blanc RO, Donaldson WF III, Fu FH. Cervical spine alignment in the immobilized football player. Radiographic analysis before and after helmet removal. Am J Sports Med. 1 997;2 5 : 226-230.

SELF - EVALUATION QU ESTIONS 1 9 . I . You are about t o perform a tracheal intubation i n an unconscious, 29-year-old male motorcycle driver who was involved in a high-speed MVC. His open-face hel­ met is in place. His airway examination is favorable, and he has no predictors of difficult bag-mask-ventilation, EGD insertion, or laryngoscopy. Regarding his helmet, which of the following statements is true? A. A skilled assistant should maintain inline stabiliza­ tion of the patient's head and neck during the airway intervention. B . If the open-face style helmet is not obstructing the line-of-sight for laryngoscopy, it may remain in place during the airway intervention.

C. A rapid-sequence induction (RSI) technique with a muscle relaxant is a reasonable choice to facilitate endotracheal intubation. D. All of the above are true. 1 9 .2. A 20-year-old motorcycle driver is involved in a high­ speed MVC. He is brought to your hospital on a spine board still wearing his full-face style helmet. His vital signs are stable and he is cooperative. He complains of pain in his left leg and his neck. You should: A. Remove his helmet immediately and provide supple­ mental oxygen. B . Carefully remove the helmet by yourself and ask the patient to inform you of any discomfort. C. Ask the patient to carefully remove the helmet him­ self while you assist him. D. Complete your primary survey assessment, provide oxygen through his helmet if necessary, and com­ plete lateral C-spine x-rays with the helmet in place prior to removing the helmet with the assistance of a skilled colleague. 1 9 . 3 . You assess a 50-year-old male motorcyclist who was involved in a high-speed MVC. He is wearing a modu­ lar full-face helmet with the face shield retracted. He is unconscious, breathing spontaneously, and is receiving oxygenation and ventilation via a Combitube'M placed in the field by paramedics after multiple failed attempts at laryngoscopy. He is obese and has a full beard. His Sp0 on Fi0 1 .00 is 87%, BP 1 1 0/70, HR 1 00, RR 2 2 24 assisted. You quickly review this case with a colleague and decide that your safest plan to establish a definitive airway is: A. Leave the Combitube'" in place indefinitely. B . Replace the Combitube'M with an LMA. C. Give succinylcholine, remove the Combitube'", and replace it with an orotracheal tube under direct laryngoscopy. D. Perform a cricothyrotomy with the Combitube'" in place and the patient breathing spontaneously.

31 1

C H A PT E R 2 0

Airway Management of a Morbid ly Obese Patient Suffering from a Cardiac Arrest Saul Pytka and Danae Krahn

CAS E PRESENTATION . . . .

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I NTRO D U CTION . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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AI RWAY MANAG EMENT . . . . . . . . . . . . . . . . . . . . . . . . . 3 1 5 S U M MARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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SELF-EVALUATION Q U ESTI O N S . . . . . . . . . . . . . . . . . .

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CASE PRESENTATION A 67-year-old woman presents to the emergency department (ED) by ambulance with a 3-hour history of increasing dyspnea associated with chest pain. She has a history of coronary artery disease, hypertension, and hyperlipidemia, but no known aller­ gies. Her medications include atenolol, low-dose aspirin, ator­ vastatin, acetaminophen with codeine, and nitroglycerin spray as needed. Prior to notifying the emergency medical services (EMS) , the patient had used three sprays of nitroglycerin every 5 to 1 0 minutes with no relief. She is placed on 1 0 Lmin-1 oxygen by face mask and is transported to the hospital. On examination after the arrival at the ED, her vital signs are: heart rate 1 1 3 beats per minute and irregular, respiration rate 3 1 breaths per minute, blood pressure 85/45 mm Hg, and Sa0 86%. She appears to be in severe 2 respiratory distress and is unable to speak more than three to four words in one breath. She is morbidly obese with an estimated weight of over 1 37 kg (300 pounds) and is 1 5 1 em (5 feet) tall with a body mass index (BMI) 60 kg·m- 2 • Chest auscultation reveals faint breath sounds with crackles over the entire lung fields, a significant decrease in air entry in both

bases combined with mild wheezing. Other findings include 1 + bilateral ankle edema, 5 heart sound, and a grade III/VI 4 systolic murmur radiating to the axilla. Her jugular venous pressure QVP) cannot be assessed because of her marked obe­ sity and short neck. Her electrocardiogram on admission to the ED reveals a pattern consistent with an acute antero-lateral myocardial infarction. The chest x-ray shows poor inflation and is also consistent with pulmonary edema. Following the initial assessment, it is noticed that the Sa0 2 decreases to 8 1 o/o and her respirations increasing to 3 5 to 40 breaths per minute. Pink froth appears from her mouth. As you prepare for airway intervention, she loses conscious­ ness. The monitor shows pulseless ventricular tachycardia.

I NTRODUCTION • Define Obesity

Obesity is the presence of an excess of body fat when compared to average values for age and gender. When the percentage of body fat exceeds 1 5% to 1 8% in men, or 20% to 25% in women, the individual is considered obese. Unfortunately, measuring body fat is not practical, as it requires sophisticated techniques. The ideal body weight (IBW) has been used frequently in clinical settings to define obesity: IBW (kg) = height (cm) - x where x is 1 00 for males and 1 0 5 for females . Patients who weigh 20% above IBW are considered over­ weight, and they are considered morbidly obese if their weight is 200% above the calculated IBW 1 The World Health Organization (WHO) specifies the use of BMI as the international method of classifying obesity. 2 It has become the standard method for defining obesity. BMI3 = body weight (kg) /height2 (m) Using the BMI, obesity is categorized as follows3:

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•

•

A person is considered overweight with a BMI of 25 to 29.9 kg·m- 2 • Obese individuals have a BMI > 30 kg·m- 2 • Obesity Class I: BMI 30 to 34.99 Obesity Class II: BMI 3 5 to 39.99 Obesity Class III: BMI 2': 40 •

•

•

It has been well established that obesity is associated with multiple medical issues including: hypertension, heart disease, congestive heart failure, diabetes mellitus, stroke, obstructive sleep apnea (OSA) , an increased incidence of perioperative wound infection, and respiratory complications. Recently, a more important predictor of long-term outcome has been shown to be the type of fat distribution, rather than BMI. "Male" or android pattern central obesity (trunk and abdomen) has been shown to correlate more with negative outcomes than "female pattern" gynecoid obesity (peripheral) , including meta­ bolic complications, risk of cardiac disease, and premature death. "Metabolic syndrome" (Syndrome X) is defined as central obesity, as described by ethnicity-specific waist circumferences measurements, and any two of the following four criteria: hypertriglyceridemia, reduced HDL-cholesterol, glucose intol­ erance, and hypertension.4 This syndrome is associated with Type 2 Diabetes, microalbuminuria, prothrombotic states, and proinflammatory states (e.g. , elevated C-reactive protein) , and represents a particularly high-risk group for the development of cardiovascular and cerebrovascular diseases. 5·6 Reducing the degree of obesity has been shown to favorably impact the progression of these disorders.7•8

• What Are the Anatomic and Physiologic

Factors That Might Contribute to the Difficulty of Airway Management in the Morbid ly Obese Patient?

In this population, numerous factors have been implicated in increasing the difficulty of bag-mask-ventilation (BMV), of extra­ glottic device (EGD) placement, of performing laryngoscopic intubation, and of obtaining a surgical airway. These include: large breasts (male and female) , excess adipose tissue in the face and cheeks, short and thick neck, large tongue, redundant palatal and pharyngeal tissue, superior and anterior larynx, limited mouth opening, limited access to the anterior neck, and limited cervical spine mobility due to occipital adipose tissue accumulation.3 The ASA definition of the difficult airway is "the clinical situ­ ation in which a conventionally trained anesthesiologist experi­ ences difficulty with face mask ventilation, tracheal intubation, or both."9 Experience and the literature suggest that obesity may contribute to a "difficult airway," as discussed below (see Chapter 1 ) . However, even when a morbidly obese patient has favorable airway assessment parameters (i.e., Mallampati I, full range of motion of neck, adequate mouth opening, etc.) , other factors can make airway intervention more challenging. There is a significant decrease in tolerable apnea time in obese, compared with that of non-obese, patients. This decrease occurs in a linear fashion as obesity increases and relates to both a decreased respiratory reserve and an increase in meta­ bolic requirements. 1 0 This decreased "respiratory reserve" is

the result of a decrease in functional residual capacity (FRC) combined with a closing capacity that intrudes on tidal vol­ ume ventilation. 10' 1 1 Furthermore, the high Fi0 employed in 2 all intubations induces absorption atelectasis, further reducing the amount of lung tissue available for gas exchange. Because of these factors, precipitous oxygen desaturation occurs when the patient is rendered apneic during airway management. 1 1 Data from Jense et al. 10 suggest that, during rapid-sequence induc­ tion (RSI) in the morbidly obese patient, hypoxemia can occur quickly (in as little as 95 seconds) , and so only one intubation should be attempted. The morbidly obese patient also has a restrictive lung defect resulting in a decreased vital capacity, expiratory reserve vol­ ume, and inspiratory capacity. 10'1 2 Auler et al. 13 found that morbidly obese patients under general anesthesia show a higher resistance throughout the respiratory system. The presence of morbid obesity is considered by many to be a predictor of difficult mask-ventilation.3'10'14 Adequate BMV requires an open airway and a tight mask seal. Creating a patent airway, and maintaining a competent mask seal in order to overcome elevated airway pressures in these patients with a restrictive lung defect due to obesity, render more dif­ ficult effective BMV. Langeron et al.14 found that the odds ratio of difficult BMV in obese patients was 2.75 ( 1 . 64-4.62, p < 0.00 1 ) . Anterior translation of the mandible (jaw thrust) to effect airway opening has been shown to be more difficult and less effective in the obese . 1 5 In this study, nine non-obese and nine obese subjects were anesthetized and given neuromuscular blocking agents. Once apneic, and with steady airway pressure applied via a nasal device, the oropharynx and velopharynx (nasopharynx) were visualized with an endoscope. The cross­ sectional areas were measured, both in the resting state and with a jaw thrust applied. In both groups of patients, the jaw thrust improved the cross-sectional area of the oropharynx. However, although an improvement with the jaw thrust maneuver occurred in the measurements of the velopharynx in the non­ obese population, no improvement was seen with this maneu­ ver in the obese patients. The authors found that obstruction persisted in the lateral plane rather than in the A-P dimension, and postulated that this was due to the redundant soft tissue around the tonsillar pillars dosing in from the sides as the ton­ sillar pillars were stretched antero-posteriorly. This may explain why CPAP or PEEP augments ventilation in the obese patient, as both laterally splint the airway. 15' 16 It may also explain why the Laryngeal Mask Airway (LMA) has been found to be an effective rescue device in the obese population. (See Section "How Effective Is the LMA in the Obese Patient.") • What Are the Special Considerations in

Patients with Obstructive Sleep Apnea?

About 5% of morbidly obese patients have OSA.3 In studying over 6000 subjects, Nieto et a!. 17 reported that most patients with OSA are not obese. Consequently, questioning patients regarding OSA should not be reserved for only the obese. The presence of snoring may be the only indicator of OSA in the general population. Snoring and obesity are important predic­ tors of difficult BMV. 14

Ai rway M a n a g e m e n t of a M o r b i d l y Obese Patient S uffe r i n g fro m a Ca rd i a c Arrest

Although difficult to quantify, a direct correlation may exist between difficult tracheal intubation and OSA. 18 Some con­ troversy exists however, and opposing data are present in the literature. In their study, Neligan et al. showed that OSA is not a risk factor for difficult intubation. They did show, how­ ever, that male gender as well as high Mallampati scores (::2: III) did predict difficulty in establishing an airway. 19 Chung et al. followed up with sleep studies on a number of patients who were found to have difficult or failed intubations at the time of surgery. Sixty-six percent of these were subsequently diagnosed with OSA. 20 In patients with OSA, airway patency is disturbed by relax­ ation of pharyngeal dilator muscles during sleep. The upper airway is soft, pliable, and narrow in these patients, which makes it collapse during sleep. Turbulent air flow through these structures produces vibrations (snoring) and collapse (apnea) . 2 1 This obstruction continues until the level of sleep is interrupted and the individual regains pharyngeal muscle tone. Drugs or alcohol can exacerbate this snoring/obstruction/apnea cycle. Consequently, sedatives, particularly the long-acting agents given in the perioperative period, can have a pronounced del­ eterious effect on the ability of this patient population to main­ tain airway patency when asleep.3 There is little question that these factors lead to increased perioperative risk for morbidity and mortality. Numerous papers address the management issues surrounding the perioperative care of this patient population. 22 Unfortunately, most recommendations appear to be based on expert opinion rather than evidence. A useful reference is the "Practice Guidelines" published by the American Society of Anesthesiologists. 2 3 Again, these are positions based primarily on the consensus of experts. The obesity hypoventilation syndrome (OHS) , also known as Pickwickian syndrome, is characterized by chronic respira­ tory insufficiency, with both obstructive and restrictive features based on pulmonary function testing. Chronic hypoxemia and hypercarbia, polycythemia, somnolence, pulmonary hyperten­ sion, and right ventricular dysfunction (cor pulmonale) char­ acterize this condition. These patients all exhibit a marked reduction in hypoxic and hypercarbic drives, measuring 1 /6 and 1 13 the response to that of controls. 24 Although some simi­ larities exist between OSA and OHS, they are not the same disease. As pointed out above, not all patients with OSA are obese, and patients with OHS do not necessarily have OSA. Due to the significant underlying pulmonary and cardiac dys­ function with the OHS population, they represent an increased perioperative risk.

not a predictive factor in determining difficulty of intubation. Of the many parameters measured in the study population, the only two that correlated with difficult laryngoscopy following RSI with cricoid pressure were large neck circumference and high Mallampati scores. A neck circumference (measured at the level of the thyroid cartilage) of 40 em was associated with a 5% incidence of difficult intubation. In the same study, difficult intubations were encountered in 3 5 % of patients with a neck circumference of 60 cm. 2 8 Of interest, larger neck circumfer­ ence has also been associated with increasing severity of OSA. 2 9 In a separate study, Ezri et al.30 also found that obesity, by itself, was not a predictor of difficult intubation. In both of the above studies, laryngoscopic view was used as a predictor for difficult intubation. Alternatively, the Intubation Difficulty Scale (IDS) has been validated and used to provide a more comprehensive assessment of intubation difficulty.31 In addition to laryngoscopic grade, the IDS scores the num­ ber of intubation attempts, different techniques tried, lifting force applied during laryngoscopy, need for external laryngeal pressure, and position of the vocal cords at intubation. Studies employing this tool suggest an increased incidence of difficult intubation (IDS > 5) in obese patients.3 2-34 That being said, BMI itself was not shown to be an independent predictor of difficulty in these cases. It is important to note that the vast majority of obese patients, with proper positioning and prepa­ ration, do not present an airway problem. The above is clearly stated in the NAP4 study which rec­ ognized obesity as representing a high proportion of patients who have difficulty, with particular emphasis on the morbidly obese. 35 The Executive Summary stated:

• Is Tracheal I ntubation More Difficult in

• Are Obese Patients at I ncreased Risk of

There is some disagreement as to whether morbid obesity is predictive of difficult intubation. The incidence of difficult intubation in the morbidly obese population has been reported to be approximately 1 3o/o to 20%. 25-27 This wide range is likely related to the inconsistent definitions of "difficult intubation" in the literature. In a study of 1 00 morbidly obese patients with BMis of > 40 kg·m - 2 , Brodsky et al. 2 8 concluded that obesity, per se, was

Obesity has been frequently listed as a risk factor for aspiration. However, recently this assumption has been challenged by a number studies that have found no increase in gastric volumes or acidity in obese subjects.36•37 Maltby et al.38 demonstrated that gastric emptying was no different in obese than in non­ obese patients and suggested that the same guidelines for fast­ ing can be applied to both patient populations. Aspiration risks and prophylaxis should be applied in the obese patients using

Morbid ly Obese Patients?

The proportion of obese patients in case reports sub­ mitted to NAP4 was twice that in the general popula­ tion, this finding was even more evident in the morbidly obese. Too often obesity was not identified as a risk factor for airway difficulty and the anaesthetic technique was not modified. Particular complications in obese patient included an increased frequency of aspiration and other complications during the use of SADs, difficulty at tra­ cheal intubation and airway obstruction during emer­ gence or recovery. When rescue techniques were necessary in obese patient they failed more often than in the non­ obese. Obesity needs to be recognised as a risk factor for airway difficulty and plans modified accordingly.

AI RWAY MANAGEMENT PREPARATION Aspiration?

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the same criteria as in the non-obese. For a detailed discussion of aspiration and risks, see Chapter 5 . • How Should t h e Morbidly Obese Patient be

Positioned for Ai rway Management?

Because of the decreased oxygen reserve in this patient popula­ tion, it is crucial to position these patients carefully for airway intervention prior to induction of anesthesia. Appropriate posi­ tioning prior to the induction of anesthesia can significantly reduce the apnea time required for intubation as well as increase the oxygen reserve. While recent literature has questioned the advantage of the sniffing position over simple head exten­ sion,39 these studies still advocate the sniffing position for obese patients. Proper sniffing position has been defined as head extension and a 35-degree flexion of the neck onto the chest.40 Achieving adequate sniffing position in a patient of IBW may include placement of a pillow under the neck and extend­ ing the head. However, in the morbidly obese patient, optimal positioning requires building a ramp of sheets or towels under the shoulders, neck, and head (Figures 20- 1 and 20-2) . This is referred to as "extreme sniffing" or "ramped" position or the "head-elevated laryngoscopy position" (HELP) where the exter­ nal auditory meatus is in line with the sternal notch. As an alternative to blankets, towels, and pillows, the Troop® Elevation Pillow can be used (see Figure 5 1 -2) . In several studies, this position has been shown to significantly improve laryngoscopic view when compared to supine positioning. For example, a comparative study of 60 morbidly obese patients by Collins et alY demonstrated a significant improvement of laryngoscopic grade in patients in the "ramped" position. Determinants of proper "ramped" positioning have been described as follows: at least a 90-degree angle between the mandible and chest; the face higher than the chest; external auditory meatus at the same horizontal level as the sternal angle.41 A second and important positioning principle involves the use of the reverse Trendelenburg position. Bed placement of 30-degree head up tilt increases FRC and compliance (both

F I G U R E 2 0 - 2 . Th i s picture s h ows a m o r b i d l y obese patient l y i n g i n a s u p i n e position w i t h the s h o u l d er, neck, a n d head rest i n g o n a stac ked "ra m p" of hos pita l l i ne n . Th i s is a n o pti m a l position for a i r­ way ma nagement a n d l a ryngoscopic intu bation for obese patients a s the exte r n a l a u d itory meatus i s at the same ho rizonta l l evel as the ste r n a l a n g l e 3 1

lung and chest wall) thereby permitting greater degrees of pul­ monary oxygen reserve42 and prolonging apneic oxygen desatu­ ration time in obese patients.43 .44 Adding continuous positive airway pressure (CPAP) of 1 0 em of H 0 pressure has been 2 shown to be an effective maneuver in reducing the degree of atelectasis associated with induction. Patients receiving positive end-expiratory pressure (PEEP)/CPAP prior to induction can be expected to have higher Pa0 values than control groups that 2 have not undergone the maneuver.45.46 However, the morbidly obese patient will still have more rapid oxygen desaturation once apneic when compared to the non-obese patients, even with CPAP. Passive oxygenation has been shown to be an important technique in significantly prolonging safety after apnea occurs. (See section "What Is the Role of Passive Oxygenation During the Management of the Difficult Airway in the Obese Patient?" in this chapter for the discussion of this topic.)

• How Should Medications be Dosed in the

Morbidly Obese Patient?

Though there is a lack of consensus regarding dose adjustments in obese patients, both the IBW and lean body weight (LBW) have been used instead of total body weight (TBW) . The LBW is a measured value, but can be estimated by the formula: LBW = (a) (weight) - b (weight2 / 1 00

F I G U R E 20- 1 . Th i s pictu re s h ows a m o r b i d l y o bese patient l y i n g i n a s u p i n e p o s i t i o n w i t h the neck a n d head rest i n g o n a reg u l a r p i l l ow. I t i s d iffic u l t t o access t h e mouth as we l l as perform d i rect l a ryngoscopy in t h i s patient l y i n g in t h i s positi o n .

X

(height) )

where a and b = 1 . 1 and 1 2 8 for men, and 1 .07 and 1 48 for women, weight in kilograms, and height in meters.47 The IBW (as presented above) can be approximated by a simple formula. IBW(kg) = height (in em) - x where x is 1 00 for males and 1 05 for females

Ai rway M a n a g e m e n t of a M o r b i d l y Obese Patient S uffe r i n g fro m a Ca rd i a c Arrest

Another suggested way to calculate the dose of these agents is to employ the adjusted body weight (ABW)48: ABW

=

IBW + 0.4 (TBW - IBW)

Several recommendations are available to guide medication dose-adjustments in the obese population. LBW is most com­ monly used as it takes into account changes in body composition with increased mass and is best correlated with cardiac output.49•50 The use of TBW to calculate the dose is particularly prob­ lematic for hydrophilic drugs. For some hydrophilic agents, the use ofTBW leads to an over calculation of the required dosage, and hence toxicity. For lipophilic agents, the additional adipose tissue increases the volume of distribution, which can influ­ ence serum concentration and prolong duration of action. Of note, succinylcholine is an exception and is dosed using TBW as pseudocholinesterase levels are increased in obese patients.49 In the obese person, not all of the excess weight is fat. Lean mass is increased, and represents 20% to 40% of the increased weight. Cardiac output is also increased, though blood supply to adipose tissues is quite low, accounting for only 5% of this value. For all practical purposes, protein binding (a major influ­ ence on volume of distribution) in obese patients is similar to that in those who are not obese. 5 1

AI RWAY MANAGEMENT • What Are the Appropriate Methods for

Den itrogenation of the Morbidly Obese Patient?

While the term pre-induction oxygenation or "preoxygenation" has been used by most to reflect denitrogenation of the lungs, it is more appropriate to use the term "denitrogenation," as it more accurately reflects the desired end result of nitrogen being washed out of the lungs. Two denitrogenation methods have been described and are equally effective for the obese patient. 10 They include: (1) four vital capacity breaths of l OO% oxygen and (2) breathing 1 00% oxygen normally (tidal-volume breathing) through a snug-fitting face mask for 5 minutes. Denitrogenation employing CPAP with 1 00% oxygen showed no significant dif­ ference when compared with standard denitrogenation tech­ niques in one study, 1 1 but proved beneficial in another.45 • How Effective Is the LMA in the Obese

Patient?

A number of studies and case reports have been published recently illustrating the effectiveness of the various laryngeal mask devices in providing ventilation and oxygenation in obese patients. The NAP4 report supports their use as a rescue device and suggest that for both routine and rescue use, laryngeal masks with additional favorable features (e.g. , higher seal pres­ sure and a gastric drainage port) should be considered. 35 Doyle and colleagues reported the management of the airway in a patient weighing 445 kg (980 lb, and BMI of 1 63 kg· m- 2) . After failing awake tracheal intubation using a flexible bronchoscope (FB) , they successfully placed a size 5 LMA-ProSeal'" awake and anesthesia was induced using sevoflurane.5 2 A surgical airway was then performed.

In a study involving 60 obese patients (BMI > 30), Natalini et al.53 have shown that both LMA-Ciassic'M and LMA-Proseal'" are effective in providing mechanical ventilation. In another effi­ cacy study of the LMA-ProSeal'" (LMAP) in the morbidly obese, Keller et al.54 induced anesthesia in 60 morbidly obese (BMI > 35 kg·m- 2) patients and inserted an LMAP. Insertion of the LMAP was successful in all patients, 90% on the first attempt, and the remaining 1 0% on the second attempt. Following adequate oxy­ genation, the LMAP was removed, and laryngoscopic intubation was successful in 54 patients (90%) on the first attempt and 4 patients (7%) on the second attempt. Failure to intubate the tra­ chea occurred in the remaining rwo patients (3%) . These patients had the LMAP reinserted and the surgery proceeded using the EGO. No significant hypoxemia was reported in any patient dur­ ing the study. Frappier et al. 55 studied 1 1 8 morbidly obese surgical patients with BMis of >45 kg·m- 2 • Following induction, all initially underwent laryngoscopy to determine the Cormack-Lehane grade. Subsequently, they all underwent attempted tracheal intubation using the intubating laryngeal mask airway (ILMA) . Tracheal intubation was successful in 1 1 4 patients (96.3%) . Laryngoscopic intubation was successful for the remaining four patients with failed ILMA attempts. No correlation berween laryngoscopic grade and failure with the ILMA was evident. There have been relatively limited reports of i-gel• and Air-Q• use in the morbidly obese population. A study by Weber et al. 56 suggested increased leak pressures and potentially faster insertion time in the overweight and mildly obese popula­ tion when using the i-gel as compared to the LMA-Unique. Shiraishi57 described awake Air-Q• placement in 20 morbidly obese patients undergoing bariatric surgery with risk factors for difficult intubation. The Air-Q• was used as a conduit for subse­ quent bronchoscopic intubation, with easy initial visualization of the vocal cords in all but one subject. There were no episodes of desaturation during the procedure. Alternatively, Gaszynski58 reported successful Air-Q• placement in 87.9% of morbidly obese patients ( n = 30) undergoing elective bariatric surgery, however, subsequent, primary attempts at blind intubation through the device were successful only 24.2% of the time. In summary, there have been multiple reports of successful laryngeal mask use in the obese population. Like other airway techniques, however, difficulty in placement of these devices may be increased and plans for airway management should account for this with multiple device sizes and additional adjuncts available. • What Are the Plans to Secure the Airway of

this Patient?

Pulseless ventricular tachycardia renders this patient a "Crash Airway" (see Chapter 2) . Airway management of this patient should take into account the principles discussed above. Management of the cardiac emergency should be guided by the most recent ACLS guidelines provided by the American Heart Association. This would include initiation of cardiac compres­ sions and defibrillation as indicated. As with any emergency intubation, every effort is made to ensure that the first attempt is the "best attempt" : •

•

Best person; Best position;

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•

•

•

Best paralysis; Best BURP; Best length and type of laryngoscope blade.

If possible, placing the patient in a "ramped position" (see Figure 20-2) with reverse Trendelenburg immediately has the potential to improve pulmonary mechanics, improve the success of BMV, and optimize the ability to provide pre-intubation oxy­ genation saturations. Help should be summoned and adjuncts and alternative airway devices, such as the rigid fiberoptic laryn­ goscopes or video-laryngoscopes (Plan B and Plan C) , should be immediately available. Direct laryngoscopy may not be difficult, unless there is a history of difficult intubation (OSA, previously failed intubation, etc.) or predictors of difficulty such as a thick neck or a high Mallampati score elicited before collapse. Induction agents are not indicated in the Crash Airway. Neuromuscular blocking agents (e. g., succinylcholine) may be required in the event the first attempt at oral intubation fails and residual muscle tone is suspected to be a factor contributing to that failure (see Crash Airway Algorithm, Chapter 2). However, it is of questionable benefit to administer succinylcholine in the presence of a pulseless VT. The risk of aspiration depends on a number of factors, includ­ ing the fact that it is an emergency, her stomach is likely to be full either from gastric juices or gas from aggressive attempts at BMV, and a positive history of gastro-esophageal reflux disease (GERD), to name a few. As failed or difficult intubation increases the risk of aspiration, cricoid pressure is employed while manag­ ing the airway. However, if intubation or airway management proves difficult in the presence of cricoid pressure, the pressure can, and should be released. It is important to recognize that cricoid pressure has never been proven to be protective, and has been demonstrated to render airway management more difficult in some situations (see Chapter 5 for detailed discussion) . If the decision to intubate her trachea was to be made prior to her arrest, the choice to use neuromuscular blocking agents to facilitate that intubation would depend on the level of confidence one has that the airway can be secured. Inherent in this is the anticipated ease of oxygenation with BMV or EGO in the event that intubation fails. If the decision is made to paralyze, the selec­ tion and dosing of induction agents should be based on the hemo­ dynamic stability of the patient. Should effective gas exchange not be possible, an "awake look'' may be employed to further evaluate the potential for a successful intubation (see Chapter 2). • What Is the Role of Passive Oxygenation

During the Management of the Difficult Airway in the Obese Patient?

As discussed above, multiple factors contribute to the rapid desaturation in the obese patient once they become apneic. This is compounded by the difficulty that may be encountered in their airway management, prolonging the time to securing a pat­ ent airway. Preoxygenation/denitrogenation certainly has been shown to prolong the apnea time before oxygen desaturation occurs, however, it is often grossly inadequate in these patients. Passive oxygenation has been demonstrated in numerous papers to be an effective way of significantly prolonging apnea time without resultant oxygen desaturation, and also reducing

the development of hypercarbia in certain scenarios. As long as a patent airway exists between the lungs and the nasophar­ ynx, oxygen will move into the alveoli due to a concentration gradient created by movement of 0 into the capillaries and 2 C0 excretion. This draws oxygen into the alveoli, and leads 2 to the removal of C0 in the opposite direction. Taha et al. 2 randomized 30 healthy patients into two groups of 1 5 patients, all with ASA 1 and 2. All were denitrogenated, and then made apneic. The control group had no supplemental oxygen. The study group had 5 L min- 1 of oxygen via nasopharyngeal can­ nula (NPC) . The control group reached their threshold oxygen desaturation of 95o/o in 3 . 6 minutes, whereas all in the study group maintained oxygen saturation of 1 00% for the full 6 minutes of the study. 59 Ramachandran took 30 obese males, and did a similar study to Taha. They were induced with total intravenous agents fol­ lowing denitrogenation. Again, 1 5 received no supplemental oxygen after induction, and the study group received 5 L min - 1 o f 0 via NPC. Simulated difficult intubation was created, and 2 carried out for 6 minutes. The study group averaged 5 .29 min­ utes before dropping to a saturation of95o/o, whereas the control group averaged 3 .49 minutes before reaching the same thresh­ old. Over half (8) of the study group still had Sp0 > 95% at 2 6 minutes whereas only 1 in the control group remained at that level. Finally, after 6 minutes, the minimal saturation in the two groups also differed, with lowest recorded Sp0 between the 2 study group and control of 94.3o/o versus 87.7%, respectively.60 More recently, a number of papers have described high­ flow humidified oxygen delivery via a nasal cannula device (Optiflow•) . The device can provide up to 70 Lmin- 1 flow and 5 to 7 em H 0 CPAP. Montanes studied the device in ICU 2 patients with preexisting hypoxemia requiring intubation. One hundred patients were divided into two groups of 50. One group used the standard non-rebreathing face mask (NRM) with a reservoir bag; the other used the high-flow nasal can­ nula (HFNC) . The HFNC provided superior protection from hypoxemia, with severe hypoxemia (Sp0 < 80%) occurring in 2 eight of the NRM versus one in the HFNC group.61 Patel and Nouraei62 studied 25 patients for emergency and difficult airways, undergoing ENT procedures. All were either known or strongly suspected to have difficult airways. They had a median Mallampati score of III as well as a Cormack­ Lehane score of 3 . Twelve were obese, with the median BMI of 30, and nine had stridor. In all of the subjects, transnasal high-flow humidified oxygen was provided with mainte­ nance of a jaw thrust during the apneic period. The patients all had THRIVE (Transnasal Humidified Rapid Insuffiation Ventilatory Exchange) for 1 0 minutes prior to induction, as well as a 40-degree head up tilt. Anesthesia was then induced. Apnea was considered the time from administration of muscle relaxation until the commencement of ventilatory support or spontaneous ventilation. THRIVE was continued during the whole period of apnea. The average apneic time was 1 7 min­ utes, with a range of 5 to 65 minutes. No patient experienced a Sp0 of < 90%. Furthermore, the mean EtC0 was 58.5 mm 2 2 Hg, with a range of 37 to 1 1 5 mm Hg. The markedly reduced rate of EtC0 rise was due to the high-flow flushing of the ana­ 2 tomic dead space and reduced shunting due to the CPAP.

Ai rway M a n a g e m e n t of a M o r b i d l y Obese Patient S uffe r i n g fro m a Ca rd i a c Arrest

Whether one uses high-flow nasal cannula, or the Optiflow• sys­ tems, a major increase in the apneic time can significantly improve safery in the management of the difficult morbidly obese patient. • What Are the Rescue Options for the Failed

Airway in the Morbidly Obese Patient?

The first rescue from failed BMV is improved BMV BMV is likely to be difficult in this patient due to soft tissue collapse of the upper airway, difficult or impossible mask seal, and noncom­ pliant lungs due to her obesity and pulmonary edema. Having an oral airway and experienced assistant to facilitate "two-handed" BMV technique may be crucial (see Chapter 8 for derails) . Management decisions in the face of the failed airway depend on whether it is a "can't intubate, can oxygenate" failed airway or a "can't intubate, can't oxygenate" (CICO) failed airway. In the former situation, there is time and practitioners may select an EGO or an alternative airway device, or a technique familiar to them. As discussed earlier, the LMA has been demonstrated to be an effective device in the morbidly obese patient due to its ability to splint the airway. If found to be effective, ventila­ tion and oxygenation can be facilitated. However, with the high pressures that may be required, adequate ventilation may prove to be challenging. In that scenario, switching to an intubat­ ing LMA (LMA-FastrachT") may allow subsequent intubation. Another option, particularly if one already has an LMA-Classic in place, is to employ the Cook Aintree" Intubation Catheter (AIC, Cook Medical Inc., Bloomington, IN) . The AIC is a hol­ low catheter that slides over a pediatric FB.63 This technique allows the use of the FB to facilitate intubation even in the situation where the practitioner has only low or average skills with the flexible bronchoscope. The loaded bronchoscope can then be passed through the LMA and advanced through the vocal cords and into the trachea. The LMA and the broncho­ scope are removed, leaving the AIC behind. An endotracheal rube (ETT) can then be advanced over the AIC and the cath­ eter removed, leaving the ETT in place (see section "Can the Flexible Bronchoscope be Combined with Other Intubation Techniques?" in Chapter 1 0) . In the latter situation of CICO, there must b e no delay and a cricorhyrotomy must be performed. While preparing to perform the surgical airway, an EGO may be attempted concurrently. In the CICO situation, it is appropriate to use alternative intu­ bating techniques, such as rhe intubating LMA, the GlideScope", the C-Mac", or the King Video-laryngoscope" guided by the skill of the practitioner. These devices have been shown to be effective in tracheal intubation in morbidly obese patients. An additional technique involves the use of combination of a video-laryngoscope (VL) along with an FB. Numerous cases have been reported in the literature, where either technique alone failed. When combining the two methods, the best view of the glottis is visualized using the VL by the most experienced practitioner. When in position with optimal view of the glottis, a second practitioner may take control of the VL, maintaining the best view. An FB is then used by the most appropriate prac­ titioner, initially guided by view through the screen of the VL, and then passed through the cords visualizing via the FB. An ETT, preloaded on the FB, is then passed over the later device.

Passage of ETT through the cords is visualized by the VL, and then confirmed by the FB once the tip of the rube is below the cords. Even in situations where a Cormack-Lehane 3 or 4 laryngoscopic view is obtained by the VL, supraglottic tissue is splinted open adequately for successful view with the FB, which was not possible without the VL. Due to the short, thick neck, performing a surgical airway in this morbidly obese patient would undoubtedly prove to be very difficult. During all of the above attempts to obtain a patent airway in the scenarios mentioned above, even with a surgical airway, apneic oxygenation should always be kept in the picture, as dis­ cussed in the section "What is the Role of Passive Oxygenation During the Management of the Difficult Airway in the Obese Patient?" of this chapter.

S U M MARY The incidence of morbid obesity is increasing in our sociery, posing both long- and short-term risks to the patient requiring airway management. Associated medical conditions affecting vital organ system reserve influence our decisions when airway management is required. Obesity alone may not predict dif­ ficult laryngoscopy, therefore highlighting the importance of thorough airway examination. However, a thick neck or high Mallampati scores do predict difficulry with laryngoscopic intubation in obese patients. Difficulty with mask-ventilation is common. Preparation for failure is important. The various airway devices highlighted in this chapter have been shown to be effective in the obese patient. It should be expected that rapid oxygen desaturation and hypoxemia might occur following induction and paralysis. However, proper positioning to maximize FRC and recruit alveoli and proper denitrogenation practices will minimize oxy­ gen desaturation. Maintenance of a patent upper airway after apnea and the use of apneic oxygenation with high-flow nasal prongs or Opriflow" have been shown to markedly increase the apneic safety threshold. Drug dosing adj ustments due to obesiry remain poorly understood for many agents. If time permits, careful "titration to effect" with intravenous induction agents may prove to be effective and safer than dosing according to body weight. Finally, the recognition of failure is crucial, as is the recogni­ tion of what rype of failure has occurred. Management pathways are guided by how much time there is, the available resources, and the experience of the practitioner. The sense of urgency in the morbidly obese patients may be worsened due to the more rapid oxygen desaturation that occurs in this population. As in all situations of airway intervention, proper planning involves the use of adjunct and alternative techniques specific for the peculiarities of the patient and the skills of the practitioner. LMAs, such as LMA-Proseal and LMA-Fastrach, FB as well as VL should be available if required. Combinations of these tech­ niques, such as FB with a loaded Aintree Intubation Catheter through an LMA-Classic, or VL-guided FB, may increase the likelihood of success when compared to the use of these instru­ ments when used alone.

31 7

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Pre-Hospita l Ai rway M a n a g e m e n t

REFERENCES 1 . Zeman F. Clinical Nutrition and Dietetics. 2nd ed. New York, NY: MacMillan Company; 1 9 9 1 :470-5 1 6. 2. World Health Organization. Global database on body mass index: BMI classification. Available at: http://apps.who. int/bmi/index. jsp?introPage =intro_3 .html. Accessed November 1 6, 20 1 6 . 3. Adams JP, Murphy P G . Obesity i n anaesthesia and intensive care. B r j Anaesth. 2000;85 : 9 1 - 1 08. 4. Alberti K, Zimmer P, Shaw J. Metabolic syndrome-a new world-wide definition. A Consensus Statement from the International Diabetes Federation. Diabetic Med. 2006;23:469-480. 5 . Deen D. Metabolic syndrome: time for action. Am Fam Physician. 2004;69:2875-2882. 6. Mitka M. Metabolic syndrome recasts old cardiac, diabetes risk factors as a "new" entiry. }AMA. 2004;29 1 :2062-2063. 7. Anderson JW, Konz EC. Obesity and disease management: effects of weight loss on comorbid conditions. Obes Res. 200 1 ;9 (suppl 4) :326S-334S. 8. Kenchaiah S , Evans JC, Levy D, et a!. Obesity and the risk of heart failure. N Eng!} Med. 2002;347: 305-3 1 3 . 9. Apfelbaum JL, Hagberg CA, Caplan RA , e t al. Practice guidelines for the management of the difficult airway: an updated report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology. 20 1 3; 1 1 8 :25 1 -270. 10. Jense HG, Dubin SA, Silverstein PI, O'Leary-Escolas U. Effect of obe­ sity on safe duration of apnea in anesthetized humans. Anesth Ana/g. 1 9 9 1 ;72:89-93. 1 1 . Cressey DM, Berthoud MC, Reilly CS. Effectiveness of continuous posi­ tive airway pressure to enhance pre-oxygenation in morbidly obese women. Anaesthesia. 200 1 ; 5 6 :680-684. 1 2. Doyle DJ, Arellano R. Upper airway diseases and airway management: a synopsis. Anesthesiol Clin North Am. 2002;20:767-787, vi. 1 3 . Auler JO Jr. , Miyoshi E, Fernandes CR, et a!. The effects of abdominal opening on respiratory mechanics during general anesthesia in nor­ mal and morbidly obese patients: a comparative study. Anesth Ana/g. 2002;94:74 1 -748. 14. Langeron 0, Masso E, Huraux C, et al. Prediction of difficult mask venti­ lation. Anesthesiology. 2000;92: 1 229- 1 236. 1 5 . lsono S, Tanaka A, Tagaito Y, et a!. Pharyngeal patency in response to advancement of the mandible in obese anesthetized persons. Anesthesiology. 1 997;87: 1 0 5 5 - 1 062. 1 6. Rothfleisch R, Davis LL, Knebel DA, deBoisblanc BP. Facilitation of fiber­ optic nasotracheal intubation in a morbidly obese patient by simultaneous use of nasal CPAP. Chest. 1 994; 1 06:287-288. 1 7. Nieto FJ, Young TB, Lind BK, et al. Association of sleep-disordered breathing, sleep apnea, and hypertension in a large community-based study. Sleep Heart Health Study. }AJ\Vl. 2000;283: 1 829- 1 836. 1 8 . Hiremath AS, Hillman DR, James AL, et a!. Relationship between dif­ ficult tracheal intubation and obstructive sleep apnoea. Br j Anaesth. 1 998;80:606-6 1 1 . 1 9. Neligan PJ, Porter S, Max B , et al. Obstructive sleep apnea is not a risk factor for difficult intubation in morbidly obese patients. Anesth Ana/g. 2009; 1 09: 1 1 82- 1 1 86. 20. Chung F, Yegneswaran B, Herrera F, et a!. Patients with difficult intubation may need referral to sleep clinics. Anesth Analg. 2008; 1 07:9 1 5-920. 2 1 . Loadsman JA, Hillman DR. Anaesthesia and sleep apnoea. Br j Anaesth. 200 1 ;86:254-266. 22. Gross JB, Bachenberg KL, Benumof JL, et a!. Practice guidelines for the perioperative management of patients with obstructive sleep apnea: a report by the American Society of Anesthesiologists Task Force on Perioperative Management of Patients with Obstructive Sleep Apnea. Anesthesiology. 2006; 1 04: 1 0 8 1 - 1 093. 23. American Society of Anesthesiologists Task Force on Perioperative Management of Patients with Obstructive Sleep Apnea. Practice guidelines for the peri operative management of patients with obstructive sleep apnea. Anesthesiology. 20 14; 1 2 0 (2):268-286. 24. Zwillich CW, Sutton FD, Pierson DJ, et al. Decreased hypoxic ven­ tilatory drive in the obesity-hypoventilation syndrome. Am J Med. 1 975;59 :343-348. 25. Buckley FP, Robinson NB, Simonowitz DA, Dellinger EP. Anaesthesia in the morbidly obese. A comparison of anaesthetic and analgesic regimens for upper abdominal surgery. Anaesthesia. 1 983;38:840-85 1 . 26. Juvin P, Lavaut E , Dupont H , e t a!. Difficult tracheal intubation is more common in obese than in lean patients. Anesth Ana/g. 2003;97: 59 5-600. 27. Voyagis GS, Kyriakis KP, Dimitriou V, Vrettou I. Value of oropharyngeal Mallampati classification in predicting difficult laryngoscopy among obese patients. Eur} Anaesthesiol. 1 998; 1 5 :330-334.

28. Brodsky JB, Lemmens HJ, Brock-Urne JG, et al. Morbid obesity and tra­ cheal intubation. Anesth Ana/g. 2002;94:732-736. 29. Katz I, Stradling J, Slutsky AS , et al. Do patients with obstructive sleep apnea have thick necks? Am Rev Respir Dis. 1 990; 1 4 1 : 1 228- 1 23 1 . 30. Ezri T, Medal ion B , Weisenberg M , et al. lncreased body mass index per se is not a predictor of difficult laryngoscopy. Can ] Anaesth. 2003; 50: 1 79- 1 83. 3 1 . Adnet F, Barron S, Racine S, Clemessy J, Fournier J, Plaisance P, Lapandry C. The Intubation Difficulty Scale (IDS ) : proposal and evaluation of a new score characterizing the complexity of endotracheal intubation. Anesthesiology. 1 997 ;87: 1 290- 1 297. 32. Juvin P, Lavaut E, Dupont H, et a!. Difficult tracheal intubation is more common in obese than in lean patients. Anesth Analg. 2003;97(2) : 5 9 5-600. 33. Gonzalez H, Minville V, Delanoue K, Mazerolles M, Concina D, Fourcade 0. The importance of increased neck circumference to intubation difficul­ ties in obese patients. Anesth Analg. 2008; 1 06 (4) : 1 1 32-1 1 36. 34. Kim W, Aim H, Lee C, et a!. Neck circumference to thyromental dis­ tance ratio: a new predictor of difficult intubation in obese patients. BJA. 20 1 1 ; 1 06(5) :743-748. 35. Cook TM, Woodall N, Frerk C. 4th National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society. Major complications of airway management in the United Kingdom. Br J Anaesth. 2 0 1 1 ; 1 06(5) : 6 1 7-63 1 . 36. Juvin P, Fevre G , Merouche M , e t a!. Gastric residue is not more copious in obese patients. Anesth Analg. 200 1 ;93: 1 62 1 - 1 622. 37. Harter RL, Kelly WB, Kramer MG, et a!. A comparison of the volume and pH of gastric contents of obese and lean surgical patients. Anesth Ana/g. 1 998;86: 1 47- 1 52. 38. Maltby JR, Pyrka S, Watson NC, et a!. Drinking 300 mL of clear fluid two hours before surgery has no effect on gastric fluid volume and pH in fasting and non-fasting obese patients. Can J Anaesth. 2004; 5 1 : 1 1 1 - 1 1 5 . 39. Adnet F, Barron SW, Lapostolle F, Lapandry C. The three axis alignment theory and the "sniffing position" : perpetuation of an anatomic myth? Anesthesiology. 1 999;9 1 : 1 964- 1 96 5 . 40. Benumof J L . Comparison of intubating positions: the end point for posi­ tion should be measured. Anesthesiology. 2002;97:750. 4 1 . Collins JS, Lemmens HJ, Brodsky JB, et a!. Laryngoscopy and morbid obesity: a comparison of the "snifF' and "ramped" positions. Obes Surg. 2004; 1 4 : 1 1 7 1 - 1 1 7 5 . 4 2 . Dixon BJ, Dixon J B , Carden JR, e t al. Preoxygenation i s more effective in the 25 degrees head-up position than in the supine position in severely obese patients: a randomized controlled study. Anesthesiology. 2005; 1 02: 1 1 1 0 - 1 1 1 5 . 4 3 . Alrermatt F. Pre-oxygenation i n the obese patient: effects of position o n tolerance t o apnoea. B]A. 2005 ;95(5):706-709. 44. Boyce J. A preliminary study of the optimal anesthesia positioning for the morbidly obese patient. Obes Surg. 2003; 1 3 ( 1 ) :4-9 . 4 5 . Coussa M, Proietti S, Schnyder P, et a!. Prevention of atelectasis forma­ tion during the induction of general anesthesia in morbidly obese patients. Anesth Analg. 2004;98: 1 49 1 - 1 49 5 . 46. Perilli V, Sollazzi L, Modesti C, e t al. Comparison of positive end­ expiratory pressure with reverse Trendelenburg position in morbidly obese patients undergoing bariatric surgery: effects on hemodynamics and pul­ monary gas exchange. Obes Surg. 2003; 1 3 :605-609. 47. Bouillon T, Shafer SL. Does size matter? Anesthesiology. 1 998;89:5 57-560. 48. Etstad BL. Dosing of medications in morbidly obese patients in the inten­ sive care unit setting. Intensive Care Med. 2004;30: 1 8-32. 49. Ingrande J, Lemmens H . Dose adjustments of anesthetics in the morbidly obese. B]A. 20 1 0 ; 1 0 5 (S 1 ) : i 1 6-i23. 50. Casati A, Purzu M. Anesthesia in the obese patient: pharmacokinetic con­ siderations. J Clin Anesth. 200 5 ; 1 7: 1 34- 1 4 5 . 5 1 . Cheymol G. Effects of obesity on pharmacokinetics implications for drug therapy. Clin Pharmacokinet. 2000;39:2 1 5-23 1 . 52. Doyle DJ, Zura A, Ramachandran M , et a!. Airway management in a 980-lb patient: use of the Aintree intubation catheter. J Clin Anesth. 2007; 1 9 :367-369. 53. Natalini G, Franceschetti ME, Pantelidi MT, et al. Comparison of the standard laryngeal mask airway and the ProSeal laryngeal mask airway in obese patients. Br J Anaesth. 2003;90: 323-326. 54. Keller C, Brimacombe J, Kleinsasser A, Brimacombe L. The Laryngeal Mask Airway ProSeal'" as a temporary ventilatory device in grossly and morbidly obese patients before laryngoscope-guided tracheal intubation. Anesth Ana/g. 2002;94:737-740. 5 5 . Frappier J, Guenoun T, Journois D, et a!. Airway management using the intubating laryngeal mask airway for the morbidly obese patient. Anesth Ana/g. 2003;96: 1 5 1 0- 1 5 1 5 . 56. Weber U, Oguz R, Potura L, Kimberger 0, Kober A, Tschernko E. Comparison of the i-geal and the LMA-Unique laryngeal mask airway in patients with mild to moderate obesity during elective short-term surgery. Anaesthesia. 20 1 1 ;66:48 1 -487.

Ai rway M a n a g e m e n t of a M o r b i d l y Obese Patient S uffe r i n g fro m a Ca rd i a c Arrest 57. Shiraishi T. Awake insertion of the air-Q intubating laryngeal airway device that facilitates safer tracheal intubation in morbidly obese patients. B}A. 2 0 1 3;6: 1 024- 1 03 5 . 5 8 . Gaszynski T. Blind intubation through Air-Q SP laryngeal mask in mor­ bidly obese patients. Eur} Anaesthesia!. 20 1 6;33:301 -302. 59. Taha SK, Siddik-Sayyid SM, El-Khatib MF, et a!. Nasopharyngeal oxygen insuffiation following pre-oxygenation using four deep breath technique. Anaesthesia. 2006;6 1 :427-430. 60. Ramachandran SK, Cosnowski A, Shanks A, Turner CR. Apneic oxy­ genation during prolonged laryngoscopy in obese patients; a random­ ized, controlled trial of nasal oxygen administration. } Clin Anesth. 20 1 0;22: 1 64- 1 68. 61. Miguei-Montanes R, Hajage D, Messika J, et al. Use of high-flow nasal oxygen therapy to prevent desaturation during tracheal intubation of intensive care patients with mild-to-moderate hypoxemia. Crit Care Med. March 20 1 5 ;43(3): 574-583. 62. Patel A, Nouraei SA. Transnasal Humidified Rapid Insuffiation Ventilatory Exchange (THRIVE) : a physiologic method of increasing apnoea tie in patients with difficult airways. Anaesthesia. 20 1 5;70:323-329. 63. Higgs A, Clark E, Premraj K. Low-skill fibreoptic intubation: use of the Aintree Catheter with the classic LMA. Anaesthesia. 2005;60: 9 1 5-920.

SELF-EVALUATION QU ESTIO N S 20. 1 . Which o f the following i s NOT true about airway man­ agement in obese patients? A. The presence of morbid obesiry is a predictor for dif­ ficult mask ventilation. B. Jaw thrust has been shown to be less effective in the obese patients. C. Airway obstruction under anesthesia in obese patients even with the application of a jaw thrust is due to a decrease in the anterior-posterior dimension of the velopharynx (nasopharynx) .

D. Precipitous oxygenation desaturation usually occurs shortly following the induction and paralysis of obese patients. E. Based on weight alone, morbidly obese patients do not pose a risk for difficult intubation. 20.2. Which of the following is NOT true of obstructive sleep apnea (OSA) ? A. The majoriry of patients with OSA are obese. B. Larger neck circumference has been associated with increased severiry of obstructive sleep apnea. C. The presence of snoring may be the only indicator of OSA in the general population. D . In patients with OSA, airway patency is disturbed by relaxation of pharyngeal dilator muscles during sleep. E. The snoring/obstruction/apnea cycle of OSA can be exacerbated by sedative and opioid medications including alcohol. 2 0 . 3 . Which of the following airway techniques known to be difficult in obese patients?

IS

NOT

A. Bag-mask-ventilation B. Surgical airway C. Light-guided intubation using a lightwand D. Laryngoscopic intubation is obese patients with thick necks E. Ventilation using a LMA

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Airway Manage ment with B lunt Anterior Nec k Trauma David A . Caro

CAS E PRESENTATION

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I N ITIAL PATI ENT ASSESSM ENT AND MANAG EMENT . . 320 AI RWAY MANAG E M E NT . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 1 OTH ER CO N S I D ERATIONS . . . . . . . . . . . . . . . . . . . . . . .

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S U MMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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SELF-EVALUATIO N Q U ESTI O N S . . . . . . . . . . . . . . . . . . . 323

CASE PRESENTATION A 25-year-old male drives into an unseen wire while he is snowmobiling. The wire strikes his anterior neck and throws him from his snowmobile. Paramedics are unsuccessful in placing an endotracheal tube (ETT) in the field. He arrives in the emergency department (ED) immobilized on a long spine board and with a cervical collar in place. He is unconscious, unresponsive to painful stimuli, and stridorous. Initial vital signs include a heart rate of 1 20 beats per minute, a blood pressure of 1 60/90 mm Hg, a respiratory rate of 24 breaths per minute, and an oxygen saturation of 93% on room air. A non-rebreather oxygen mask is applied, and his oxygen saturation increases to 97%. Palpation demonstrates no obvious subcutaneous air, but there is a large abrasion across the anterior and lateral areas of the neck (Figure 2 1 - 1 ) . Palpation of the larynx demonstrates crepitus and slight anatomic distortion. Plans begin immedi­ ately to further protect and secure the airway.

I N ITIAL PATI ENT ASSESS MENT A N D MANAG E M E NT • What Are the I m porta nt Considerations in

Eva l uati ng This Patient?

Upon arrival at the ED, the team should follow a protocol that is consistent with the guidelines of the Subcommittee of Advanced Trauma Life Support" of the American College of Surgeons Committee on Trauma. 1·3 Aggressive initial management and a high index of suspicion for associated injuries are key steps in the successful management of patients with this type of injury. A young patient with no significant medical history should have adequate cardiorespiratory reserve. His initial oxygen satu­ ration is concerning, which prompts the addition of supple­ mental oxygen. His depressed level of consciousness could be due to a number of factors; anoxic injury to the brain or spi­ nal cord must be a consideration. His blood pressure, elevated pulse rate, and use of accessory muscles of respiration would suggest that his cervical cord is essentially intact. Despite two small studies which suggest that laryngotracheal injury is com­ patible with a normal cervical spine,4·5 the airway practitioner must assume that this patient has a cervical spine fracture until proven otherwise. 2"6 Other associated injuries can occur with this type of "clothesline injury." These include facial lacerations, vascular injuries, laceration of the esophagus/ and injury to the recur­ rent laryngeal nerve.8 It is imperative to thoroughly evaluate the patient after first ensuring airway, breathing, and circulation. • What Are the Airway Priorities in Th is

Patient?

The urgency of the presentation places the airway practitioner in a difficult situation. Unfortunately, a comprehensive evalua­ tion of the airway will not be feasible. It is possible to anticipate

Ai rway M a nagement with B l u nt Anterior Neck Tra u m a

junction; four o f these seven were successfully intubated while the others required emergency tracheotomy. 17 Cricothyrotomy may be very difficult in laryngeal trauma, as normal anatomic landmarks may be distorted, making it diffi­ cult to identifY the larynx, the cricothyroid membrane, and the cricoid ring. In addition, subcutaneous air may compromise the capacity to identifY the trachea to perform percutaneous needle puncture and for this reason, an open surgical technique is the preferred surgical approach (see Chapter 14 for details) .

AI RWAY MANAGEMENT • What Should We Consider in Managing Th is

Patient's Airway?

F I G U R E 2 1 - 1 . Th i s pictu re s h ows that t h i s "c l oth es l i ne i nj u ry" patient h a s a l a rge a bras i o n across the a nterior a n d l atera l a reas of the neck.

where difficulties will arise, however, and rapid anatomic and physiologic evaluation of the patient is essential. Anatomic considerations in this patient include the poten­ tial for laryngeal fracture, tracheal disruption, and an expanding hematoma which could impinge on the airway; all of these may be difficult to detect and could compromise airway patency.9'10 Blunt anterior neck trauma can also negatively influence all four components of initial airway management in this patient: bag-mask-ventilation (BMV) , use of the extraglottic devices (EGOs) , laryngoscopy and intubation, and cricothyrotomy. The anatomic concerns could lead to physiologic dysfunc­ tion; oxygenation and ventilation could both present problems. Difficulty with BMV could stem from either anatomical upper airway distortion due to the trauma itself, tracheal disruption, or to trauma related to prior intubation attempts. Additionally, the use of EGOs may be contraindicated in the setting of supraglot­ tic or glottic disruption or distortion. 1 1-13 The airway practitioner should anticipate difficult laryngos­ copy. Supraglottic or glottic distortion may hinder visualization of the vocal cords. In the event the practitioner elects to pursue direct laryngoscopy, a Miller blade may be the preferable blade, as it may provide better control of the epiglottis and a more direct line-of-sight vision. 14 Video-laryngoscopy can provide superior views of the glottis15'16 and may be preferable unless airway bleed which cannot be controlled or suctioned obscures the camera view. However, it must be understood that a clear view of the cords does not guarantee successful endotracheal intubation in this case. One must recognize that blunt anterior airway trauma may result in disruption or transection of the trachea distal to the glottis. 2 Tracheal transection may result in obstruction to tube passage or placement of the tube in a false passage through the tracheal disruption. Orotracheal laryngoscopy cannot detect this injury and may lead to a false sense of security relative to the "ease" of intubation. 17 One case series demonstrated six of seven tracheal disruptions to be at the cricothyroid/tracheal

This airway is not a "crash airway," but it is a difficult one and needs to be secured urgently. Difficulty should be expected with BMV and laryngoscopy; the airway is possibly disrupted and neck mobility is limited. Difficulty can also be anticipated with EGO utilization and with cricothyrotomy (potential for hema­ toma and laryngeal/tracheal distortion) . Summoning help is the first step in the management of this patient. There is some time to formulate a plan. The use of par­ alyzing agents or drugs which might lead to respiratory depres­ sion should be avoided in this patient. Conversely, coughing could worsen the inj ury, or could further compromise a trau­ matized spinal cord. Careful sedation and topical anesthesia are appropriate in this patient, and in-line stabilization of the cervi­ cal spine is an absolute requirement. Typically, orotracheal intubation should be performed by . . 1mme · . Iy ava1· 1 abl e. 18 19 d I aryngoscop1st th e most expenence d late In addition, in-line stabilization of the cervical spine should be employed to protect against exacerbating an unstable cervical injury. Further, in a patient who has a potentially disrupted dis­ tal airway, the procedure of choice is intubation using a flexible bronchoscope (FB) . 1 9-2 1 This technique permits visualization as one advances into the trachea and ensures that the ETT is not advanced into a blind passage. Traditional intubation with orotracheal, direct- or video-laryngoscopy can result in disrup­ tion of false passages or creation of pseudo-lumens which could compromise the patient's airway. Even the gentle placement of an Eschmann Introducer (EI) ("gum-elastic bougie") may cre­ ate an airway obstruction in these patients, 1 '2' 19• 22 although case reports exist of successful "bougie" -guided tracheal intubation in patients with tracheal inj ury penetrating neck wounds. 2 3 Confirmation of correct placement with an FB is important. A failed airway mandates an attempt at cricorhyrotomy. 1 8•19 ·

• Step by Step, What Is the Best Way to

I ntubate the Trachea of This Patient?

Timing is key. If time permits, the FB equipment should be prepared. Additionally, laryngoscopy and cricothyrotomy/tra­ cheotomy equipment should be opened at the bedside and the patient's neck should be prepped and anesthetized. A BMV device, suction, and airway adjuncts (such as oral and nasal air­ way devices) should be prepared. The primary plan would be to perform an awake flexible bronchoscopic intubation assisted

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Pre-Hospita l Ai rway M a n a g e m e n t

by procedural sedation and topical anesthesia. 2'19 In a pediatric patient, oral intubation with a smaller sized ETT might be pref­ erable. 2 If forced to act, the plan must change to an attempt at an oral direct- or video-laryngoscopy assisted with a bougie or a primary cricothyrotomy dependent on the airway practitioner's experience and capabilities. 2·18·19 Denitrogenation with a non-rebreather mask is essential. A well-oxygenated patient gives the airway practitioner a cushion of time in the event tracheal intubation is difficult and requires more time. 24 Steadily declining oxygen saturations may mandate assisted ventilation by a bag-mask. It is important to reiterate that EGOs are contraindicated in this patient as they may actually worsen the existing airway distortion. In the presence of oxygen desaturation and the airway practitioner is unable to oxygenate with a bag-mask, an immediate surgical airway is indicated. 1 8 Waiting for nebulized o r atomized 4% lidocaine t o provide topical anesthesia might be counter-productive, as these agents typically require 1 5 minutes to take effect. 25'26 Anti-sialogogues might be considered if time permits, although should not delay attempts at sedation and laryngo-bronchoscopy. Numerous sedating agents may be considered, including ketamine, propofol, midazolam, or etomidate. Ketamine (with or without propofol) is a good choice for this patient as it car­ ries the benefit of analgesia, along with sedation, before the rare complication of associated laryngospasm, or emergence reac­ tion. 27' 2 8 Propofol and midazolam may have the advantage of practitioner's familiarity and ease of titration, although both drugs can potentially precipitate complete obstruction through a loss of muscle tone. 2 9'30 Dexmedetomidine might be a consid­ eration if extra help is available to titrate the drip to effect.31·32 The advantage of etomidate is its relative cardiovascular stability. However, the potential myoclonus associated with etomidate33 may place the potential unstable cervical spine and patency of a possible tenuous airway at risk. Neuromuscular blocking agents should be avoided. 2 '18 The amount of time the practitioner has to perform bronchoscopy and intubation will depend on the ability to maintain oxygen saturation. High-flow nasal oxygen during the bronchoscopic attempt might assist to provide prolonged maintenance of oxy­ genation.34 A change of plan is indicated if glottic structures cannot be seen during the awake-look. Oxygen desaturation, failure in ventilation, or failure to visu­ alize the airway after several viewing attempts (no more than three) indicate a failed airway. 18 In this circumstance, cricothy­ rotomy is in order. 2'19 Open cricothryotomy is preferable to per­ cutaneous techniques for the reasons stated above, including the creation of a false passage. This method allows the practitioner to identifY the trachea and intubate under direct visualization. Blind attempts at finding the distal airway are rarely successfuJ.3·35

OTH E R CO N S I D E RATIONS • What Are the Concerns with Ventilation and

Post-I ntubation Care?

Once the trachea is intubated, ventilation takes priority. The use of capnometry will ensure that the ETT is in the trachea and that the lower respiratory tree is being ventilated.36 Care

must be taken to secure the ETT in place, as dislodgement could be disastrous. Sedation is in order, as is continued pro­ tection of the cervical spine until fracture, dislocation, and ligamentous disruption of the cervical spine have been ruled out. Neuromuscular blockade at this point may also be in order if this patient is endangering his spine by excessive movement. • What Are Potential Postsu rgica l

Compl ications Associated with "Clothesline I nju ries"?

Following the repair of the laryngotracheal and cervical spine injuries, several serious postoperative complications may occur. These include voice compromise, recurrent laryngeal nerve damage, esophageal disruption, mediastinal infection, tra­ cheoesophageal fistula, subglottic stenosis, neurologic injury, and carotid artery injury. 2'8' 37'38 In a retrospective review of clothesline injury in children and adolescents (on all-terrain vehicles), between 1 998 and 2003, Graham et al.39 reported that all patients ( n = 7) had significant neck and/or facial lac­ erations, with long-lasting disfigurement. One of the patients also had a functional impairment. Another retrospective review from 1 995 to 2008 identified 35 pediatric patients with blunt laryngotracheal injuries; of the 1 1 "major" inj uries, all required tracheotomy, and all but one of these ultimately underwent decannulation. 40 • What Other Alternative Should be

Considered if Secu ring the Airway Is not Possible for a Patient with a "Clothesline I nju ry"?

Extracorporeal circulation via a femoral-femoral cardiopulmo­ nary bypass (CPB) , placed with the use of local anesthesia and a portable unit, can be a life-saving method of oxygenation and could have an important role in managing patients with a severely disrupted trachea. This can provide a safe solution for oxygenation when tracheal intubation or a surgical airway is either unsuccessful or too hazardous. However, a review of the literature did not uncover the use of CPB in airway com­ promise from "clothesline injury." Furthermore, establishment of a femoral-femoral bypass requires at least 1 5 to 20 minutes, even in experienced hands41 making it impractical and difficult to apply in emergency situations.

S U M MARY In summary, blunt anterior neck injury poses a unique chal­ lenge to airway management. Care must be taken to protect airway reflexes whenever an inability to intubate is anticipated. The airway practitioner must recognize the many barriers to airway management that can prevent intubation, including an obstructing hematoma or a transected trachea. Intubation using a flexible bronchoscope is the ideal method of intubation in these patients, as the visualization it provides gives reassur­ ance that the trachea is contiguous.

Ai rway M a nagement with B l u nt Anterior Neck Tra u m a

REFERENCES I . Butler AP, Wood BP, O'Rourke AK, Porubsky ES. Acute external laryn­ geal trauma: experience with 1 1 2 patients. Ann Otol Rhinal Laryngol. 2005; 1 1 4(5) :36 1 -368. 2. Chatterjee D, Agarwal R, Bajaj L, Teng SN, Prager JD. Airway manage­ ment in laryngotracheal injuries from blunt neck trauma in children. Paediatr Anaesth. 2 0 1 6;26(2) : 1 32- 1 38 . 3 . Edwards WH, Morris ]A, DeLozier J B , Adkins RB . Airway inj uries. Th e first priority in trauma. Am Surg. 1 987; 5 3 (4) : 1 92- 1 97. 4. Aufderheide TP, Aprahamian C, Mateer JR, et al. Emergency airway man­ agement in hanging victims. Ann Emerg Med. 1 994;24 (5): 879-884. 5 . Penney OJ, Stewart AHL, Parr MJA. Prognostic outcome indicators fol­ lowing hanging inj uries. Resuscitation. 2002; 5 4 { 1 ) : 27-29. 6. Nikolic S, Micic J, Atanasijevic T, Djokic V, Djonic D. Analysis of neck injuries in hanging. Am J Forensic Med Pathol. 2003;24 (2) : 1 79- 1 82. 7. Hamid UI, Jones JM. Combined tracheoesophageal transection after blunt neck trauma. J Emerg Trauma Shock. 20 1 3;6{2) : 1 1 7- 1 22. 8. LeJeune FE. Laryngotracheal separation. Laryngoscope. 1 978;88{12) : 1 956-1 962. 9. Stassen NA, Hath JJ, Scott MJ, et al. Laryngotracheal inj uries: does injury mechanism matter? Am Surg. 2004;70 (6) : 522-525. I 0. Sidell D, Mendelsohn AH, Shapiro NL, St John M. Management and outcomes oflaryngeal injuries in the pediatric population. Ann Otol Rhinal Laryngol. 20 1 1 ; 1 2 0 { 1 2) : 787-795 . 1 1 . Wakeling H G , Nightingale J. The intubating laryngeal mask airway does not facilitate tracheal intubation in the presence of a neck collar in simu­ lated trauma. Br J Anaesth. 2000;84{2) :254-256. 12. Pollack CV. The laryngeal mask airway: a comprehensive review for the emergency physician. J Emerg Med. 200 1 ;20 ( 1 ) : 53-66. 13. Donatelli J, Gupta A, Santhosh R, et al. To breathe or not to breathe: a review of artificial airway placement and related complications. Emerg Radial. 20 1 5 ;22 {2) : 1 7 1 - 1 79. 1 4 . Arino JJ, Velasco JM, Gasca C, Lopez-Timoneda F. Straight blades improve visualization of the larynx while curved blades increase ease of intubation: a comparison of the Macintosh, Miller, McCoy, Belscope and Lee-Fiberview blades. Can ] Anaesth. 2003;50{5) : 5 0 1 -506. 1 5 . Lim HC, Goh SH. Utilization of a Glidescope videolaryngoscope for orotracheal intubations in different emergency airway management set­ tings. Eur J Emerg Med. 2009; 1 6 (2) :68-73. 16. Brown CA III, Bair AE, Pallin OJ, Laurin EG, Walls RM; National Emergency Airway Registry (NEAR) Investigators. Improved glottic expo­ sure with the video Macintosh laryngoscope in adult emergency depart­ ment tracheal intubations. Ann Emerg Med. 20 1 0;56(2): 83-88. 1 7 . Wu M, Tsai Y, Lin M, Hsu I, Fang Y. Complete laryngotracheal disruption caused by blunt inj ury. Ann Thorac Surg. 2004;77(4) : 1 2 1 1 - 1 2 1 5 . 1 8 . Walls RM. Identification o f the difficult and failed airway. In: Walls RM , ed. Manual of Emergency Airway Management. 4th ed. Philadelphia, PA: Lippincott Williams & Wilkins. 20 1 2 : 8-22. 1 9. Schaefer SD. Management of acute blunt and penetrating external laryn­ geal trauma. Laryngoscope. 20 1 4; 1 24 { 1 ) :233-244. 20. O'Mara W, Hebert AF. External laryngeal trauma. J La State Med Soc. 2000; 1 52(5) : 2 1 8-222. 2 1 . Heidegger T, Starzyk L, Villiger CR, et al. Fiberoptic intubation and laryngeal morbidity: a randomized controlled trial. Anesthesiology. 2007; I 07{4) : 585-590. 22. Arndt GA, Cambray AJ, Tomasson J. Intubation bougie dissection of tracheal mucosa and intratracheal airway obstruction. AnesthAnalg. 2008; I 07(2):603-604. 23. Steinfeldt ], BeyTA, Rich JM. Use of a gum elastic bougie (GEB) in a zone II penetrating neck trauma: a case report. J Emerg Med. 2003;24 {3) :267-270. 24. Mort TC. Preoxygenation in critically ill patients requiring emergency tra­ cheal intubation. Crit Care Med. 2005;33 { 1 1 ) : 2672-2675. 2 5 . Sun HL, Wu TJ, Ng CC, Chien CC, Huang CC, Chie WC. Efficacy of oropharyngeal lidocaine instillation on hemodynamic responses to orotra­ cheal intubation. J Clin Anesth. 2009 ; 2 1 (2) : 1 0 3 - 1 07. 26. Xue FS, Liu HP, He N, et al. Spray-as-you-go airway topical anesthesia in patients with a difficult airway: a randomized, double-blind comparison of 2% and 4% lidocaine. Anesth Ana/g. 2009; 1 0 8 {2) : 536-543. 27. Gallo de Moraes A, Racedo Africano CJ, Hoskote SS, et al. Ketamine and propofol combination ("ketofol") for endotracheal intubations in critically ill patients: a case series. Am J Case Rep. 20 1 5 ; 1 6: 8 1 -86. 28. Jabre P, Avenel A, Combes X, et al. Morbidity related to emergency endotracheal intubation-a substudy of the KETAmine SEDation trial. Resuscitation. 2 0 1 1 ;82(5) : 5 1 7-522. 29. Choi YF, Wong TW, Lau CC. Midazolam is more likely to cause hypoten­ sion than etomidate in emergency department rapid sequence intubation. Emerg Med]. 2004;21 ( 6): 700-702. 30. Win NN, Fukayama H, Kohase H, Umino M. The different effects of intravenous propofol and midazolam sedation on hemodynamic and heart rate variability. Anesth Ana/g. 2005 ; 1 0 1 { 1 ) : 97- 1 02.

3 1 . Kunisawa T, Nagata 0, Nagashima M, et al. Dexmedetomidine sup­ presses the decrease in blood pressure during anesthetic induction and blunts the cardiovascular response to tracheal intubation. J Clin Anesth. 2009;2 1 (3): 1 94- 1 99. 32. Chu KS, Wang FY, Hsu HT, Lu IC, Wang HM, Tsai CJ. The effectiveness of dexmedetomidine infusion for sedating oral cancer patients undergoing awake fibreoptic nasal intubation. Eur] Anaesthesia!. 2 0 1 0;27( 1 ) :36-40. 33. Guier A, Satilmis T, Akinci SB, Celebioglu B, Kanbak M. Magnesium sulfate pretreatment reduces myoclonus after etomidate. Anesth Analg. 2005; 1 0 1 (3) :705-709. 34. Badiger S, John M, Fearnley RA, Ahmad I. Optimizing oxygenation and intubation conditions during awake fibre-optic intubation using a high­ flow nasal oxygen-delivery system. Br] Anaesth. 20 1 5 ; 1 1 5 (4) :629-632. 35. Shweikh AM, Nadkarni AB . Laryngotracheal separation with pneumoperi­ cardium after a blunt trauma to the neck. EmergMedj. 200 1 ; 1 8 ( 5 ) :4 1 0-4 1 1 . 36. Hogg K, Teece S . Towards evidence based emergency medicine: best BETs from the Manchester Royal Infirmary. Colourimetric C0 {2) detector com­ pared with capnography for confirming ET tube placement. Emerg Med]. 2003;20(3):265-266. 37. Aouad R, Moutran H, Rassi S. Laryngotracheal disruption after blunt neck trauma. Am ] Emerg Med. 2007;25 (9) : 1 084.e l -2. 38. Smith DF, Rasmussen S, Peng A, Bagwell C, Johnson C. Complete trau­ matic laryngotracheal disruption-a case report and review. Int J Pediatr Otorhinolaryngol. 2009;73 ( 1 2) : 1 8 1 7- 1 820. 39. Graham J, Dick R, Parnell D, Aitken ME. Clothesline injury mechanism associated with all-terrain vehicle use by children. Pediatr Emerg Care. 2006;22 { 1 ):45-47. 40. Wootten CT, Bromwich MA, Myer CM. Trends in blunt laryngotracheal trauma in children. Int] Pediatr Otorhinolaryngol. 2009;73(8) : 1 07 1 - 1 075. 41. Belmont MJ, Wax MK, DeSouza FN. The difficult airway: cardiopulmo­ nary bypass-the ultimate solution. Head Neck. 1 998;20(3) :266-269.

SELF-EVALUATION QU ESTIONS 2 1 . 1 . A patient presents with stridor and an oxygen saturation of 85%. What is the ventilation device of choice to attempt to provide oxygenation after passive means have failed? A. Laryngeal Mask Airway B. Intubating Laryngeal Mask Airway C. Bag-valve-mask device D. King LTM Airway E. Combirube'" 2 1 .2 . What method of oxygenation can be used during bron­ choscopic intubation in an attempt to maintain oxygen saturation? A. Bilevel positive airway pressure B. Non-rebreather mask C. Nasal cannula D. High-Bow nasal oxygen E. Venturi mask 2 1 . 3 . What are the limitations of percutaneous cricothyrotomy in the setting of blunt anterior neck trauma with a con­ comitant laryngeal fracture? A. Subcutaneous air may mimic intratracheal air, pro­ viding false localization. B. Airway distortion may not allow readily identifiable, percutaneous airway structures. C. Distal tracheal disruption may not be identified. D. Advancement of the guidewire through the needle may be difficult. E. All of the above.

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C H A PT E R 2 2

Airway Manage ment in the Emergen cy De part ment John C. Sak/es and Michael F. Murphy

CAS E PRESENTATION

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I NTRO DUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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H I STORY . . .

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U N IQ U E F EATU RES . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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S U MMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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SELF-EVALUATIO N Q U ESTI O N S . . . . . . . . . . . . . . . . . . . 329

CASE PRESENTATION A 2 1 -year-old man is brought to the emergency department (ED) after sustaining a close range shot gun blast to the face and neck. He appears intoxicated and has an altered mental status. He intermittently becomes very agitated and combat­ ive. He is unable to give a coherent history. His viral signs are as follows: BP 1 60/ 1 0, HR 1 20, RR 26, temperature 37. 8oC. Room air oxygen saturation is 97%. There are numerous pel­ let wounds to the left side of the face and neck with tissue loss and active bleeding. There is a small hematoma on the left side of the neck and subcutaneous air can be palpated in the region. The larynx can be palpated and appears to be slightly off the midline. When he speaks, his words appeared slurred. It is difficult to ascertain whether his voice is hoarse, but there is no overt stridor. The lungs are clear bilaterally with equal breath sounds . The patient is in need of immediate airway control.

I NTRODUCTION • What Is It About Managing the

Airway in the ED That Makes It "Different"?

Making critical, lifesaving decisions in the face of incomplete information is fundamental to the practice of emergency medi­ cine. Expert management of the emergency airway is a defining skill of emergency medicine. Emergency physicians must be skilled in all aspects of airway management and must have immediate access to all necessary equipment and medications, including neuromuscular blocking agents. Patients requiring emergency airway management present, often unexpectedly, to the ED. Many of the patients have characteristics associ­ ated with difficult intubation and have significant physiologic derangements, but the urgency of the airway problem fre­ quently prevents deferral or even consultation. Frequently, oth­ ers have already tried and failed to manage the airway, resulting in airway trauma which compounds the difficulty faced by the next practitioner. Accordingly, the emergency practitioner must be both capable and constantly prepared to undertake skilled and timely intervention in patients with compromised airways, and to plan an approach that takes into account all potential difficulties and incorporates within it backup plans (Plan B, Plan C, etc.) . • Who Is Primarily Responsible for Managing

the Ai rway in the ED?

Airway evaluation and management is the first priority of resuscitation and establishing a patent airway to maintain oxygenation takes precedence over all other activities . That

Ai rway M a n a g e m e n t in the E m e rg e n cy Depa rtment

is not to say that concurrent evaluation and management activities should not occur, it simply says "Do this first! " identifying that the patient requires airway management does not necessarily mandate that the management be undertaken immediately; it simply establishes that early, deliberate airway management is indicated. In some cases, the patient will be apneic with an unprotected airway, and airway management will supersede virtually all other evalu­ ation and management. In other cases, the practitioner will identify that early airway intervention is required, and plan to provide it early during the course of comprehensive and coordinated care. The emergency physician has final responsibility for ensur­ ing definitive management of the airway for patients presenting to the ED, which might, at times, require the advice and help of other specialists such as anesthesiologists, otolaryngologists, or intensivists.

•

•

•

•

•

•

•

Determining the best method of airway management for the particular circumstances at hand and having a backup plan in the event of failure. Understanding the risks and benefits of each possible approach. Optimizing the patient's cardiopulmonary status before intubation. Deciding which pharmacologic agents to use, in what order, and in what doses. Managing the airway in the context of the patient's overall condition. Using any of a number of airway devices to achieve a definitive airway while minimizing the likelihood, severity, and duration of hypoxemia or hypercarbia. Recognizing when the planned airway intervention has failed and an alternative (rescue) technique is required. Being able to rapidly identify when to call for assistance and what type of assistance might be required.

• What Are the Indications for Tracheal

I ntubation in the ED?

The indications for tracheal intubation in the ED are straightforward: •

•

•

Inability of the patient to maintain or protect the airway Inability to maintain adequate gas exchange A predictable clinical deterioration in maintaining the airway or adequate gas exchange

Early establishment of a patent airway and prov1s1on of adequate oxygenation are critical to patient survival. Equally important is the ability to predict an impending loss of airway patency or gas exchange capability, particularly if the patient will be subjected to diagnostic studies in areas outside the ED, or transported by land or air to another facility. Subsequent decisions as to how and when the airway should be managed will depend on numerous factors, including the skills and experience of the practitioner, the equipment avail­ able, the condition of the patient, and the anatomy of the airway.

• Is There a Conceptual Framework Which

the Emergency Physician or Other Consu ltants Employ in Approaching the Ai rway in the ED?

It is widely recognized that a conceptual framework focusing on rapid airway evaluation, critical action analysis and perfor­ mance, and facility with an array of airway management tech­ niques minimizes the risk of failure and improves outcome. 1 To be precise, in an emergency, the airway practitioner must be capable of the following: •

Rapidly assessing the urgency of the situation and the patient's need for intervention.

H I STORY • How Did Ai rway Management in the ED

Evolve to Where It Is Today?

Emergency airway management for much of history consisted of various forms of back-pressure/arm-lift "artificial respira­ tion," or mouth-to-mouth, mouth-to-nose, and bag-mask­ ventilation (BMV) by minimally trained practitioners until the 1 960s when resuscitation research identified airway manage­ ment failure as a crucial issue affecting outcome. 2- 5 By the early 1 970s, tracheal intubation was recognized as an essential part of the skill set for physicians providing emergency care, but most physicians staffing emergency departments were trainees or practicing physicians with little or no formal training in emergency medicine. Intubation was generally accomplished without neuromuscular blocking agents, using either the oral or the nasal routes, sometimes requiring heavy sedation before airway management could be attempted. Intubation using a sedative, such as a benzodiazepine, often accompanied by an opioid, became a common practice despite its frequent failures and complications. The advent of emergency medicine residency training pro­ grams in 1 970 and the rapid growth of the specialty through the ensuing two decades established a large cadre of trained emer­ gency medicine specialists and led to the rapid deployment of neuromuscular blockade to facilitate tracheal intubation. By the late 1 980s, the use of neuromuscular blockade for this purpose was well established in emergency medicine residency training programs, and had been dubbed "rapid sequence intubation" (RSI) in distinction to the anesthesia term "rapid sequence induction."6 By the mid to late 1 990s, neuromuscular block­ ade was widely used and it became evident that neuromuscular blockade not only made the technical task of intubation easier

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Ai rway M a n a g e m e n t in the E m e rg e n cy Room

and faster, but also resulted in greater success with lower com­ plication rates. 6 However, a need clearly emerged for a consistent framework to identify patients at risk for difficult and possibly failed laryn­ goscopy and intubation, to develop a reliable approach to such patients, and to expand the rescue options beyond the single choice of cricothyrotomy. The challenges facing emergency airway practitioners today include: 1 . Restricting the use of neuromuscular blockade only to patients in whom there is a strong likelihood that tracheal intubation will be successful or that gas exchange can be maintained by some other technique in the event of failure; 2. Selecting an alternative approach for those patients in whom a difficult or impossible intubation may be anticipated; 3 . Ensuring the success for alternative rescue devices or tech­ niques in the event of intubation failure.

Emergency airway management situations are characterized by several unique features: •

•

•

•

•

U N IQ U E FEATU RES • How Common Is the Difficult and Failed

Airway in the ED?

Difficult direct laryngoscopic intubations are common in emergency practice, the incidence being as high as 20% of all emergency intubations. However, the incidence of intubation failure is quite uncommon, being in the 0 . 5 % to 2 . 5 % range. Moreover, the disaster of being unable to intubate or ventilate rarely occurs ( 0. 1 o/o-0 . 5 o/o) . 6 It is crucial to realize that in the case of a difficult intuba­ tion, the same standard applies as for a routine intubation; the practitioner must secure the trachea with a cuffed tracheal tube. In the case of a failed airway (e.g., "can't intubate, can't oxygen­ ate"), the approach is focused on rescue and in keeping the patient alive and well oxygenated. Thus, the devices, techniques, and even the approach differ in these two situations. A difficult airway is managed in an "anticipatory'' way; a failed airway is managed in a "reactive" way. In 2002, Walls coined the phrase "The 'Difficult Airway' is something you anticipate; the 'Failed Airway' is something you experience."7 • What Is U n ique About Airway Management

in an ED?

Emergency airway management may be in an ED, or extend beyond the ED to those locations where emergency practitio­ ners are called to manage airways, or to be directly responsible for their management by surrogate providers such as para­ medics. These locations include the out-of-hospital setting, in-patient wards, intensive care units, diagnostic units such as x-ray or radiotherapy, and other sites.

•

Clinical evaluation, not blood gases, is used to assess the adequacy of ventilation and judge the need for intubation in the acutely ill patient. The patient has a full stomach and is at high risk for aspiration. The airway must be secured with a cuffed tracheal tube. "Canceling the case," "awakening the patient," or signifi­ cantly delaying airway management is not an option, nor in most cases, is any other form of airway management that does not protect the airway (beyond the temporary use of an extraglottic device) . Critical decisions must be made with less informa­ tion than in almost any other setting. This, in fact, is the essence of emergency medicine and highlights the importance of expeditious and planned strategies for air­ way evaluation and management (see Chapters 1 and 2 for details) . The need for intubation is ordinarily obvious, but in an emer­ gency, the decision to intubate is often dependent on having knowledge of the natural course of the disorder or injury rather than on the patient's precise clinical status at the time of the evaluation. There are few other situations in medicine in which judgment and knowledge of the anticipated clinical course of a disorder are so crucial. Erring on the side of caution: Intubate earlier rather than later. Be especially cautious of penetrating neck wounds with evidence of injury to the airway itself (subcutaneous air) or the vascular system (hematoma-it does not have to appear to be "expanding") . Both the presence of such injuries and their apparent time course are important. The patient who presents 1 2 hours after sustaining a penetrating neck injury has withstood the test of time. A simi­ larly appearing injury 1 0 minutes after injury is an unknown, and must be assumed to present an immi­ nent risk. Do not paralyze a patient (ordinarily RSI) if you are not confident that you can oxygenate the patient successfully with a BMV unit or an EGO. If these fail, a surgical airway is required, and this pro­ cedure must be planned for. Anticipating this proce­ dure requires assessing the difficulty for each approach to managing the airway prior to embarking on Plan A (see Chapter 2) . Do not "sit on" patients with upper airway obstruction or insist on taking the patient out of the ED (e.g. , to the CT scan or to the OR) unless it is absolutely clear that the patient's condition is stable enough and you are confident you can successfully secure the airway if needed. Observing the patient presents the risk that anatomy will worsen and obstruction will ensue, at which time the patient will be much more difficult to intubate and the need for doing so will be much greater. In addition, call for help early. Asking for help is not a failure. •

•

Ai rway M a n a g e m e n t in the E m e rg e n cy Depa rtment

• How Should One Proceed in

Managing the Airway in an Emergency?

Once it has been decided that intubation is indicated, the focus must be on what kind of airway problem is present and what is the correct course of action? (see Chapter 2). •

•

•

•

Is this a "Crash Airway" situation in which the patient is unconscious, unresponsive, and near death? Is this a "Difficult Airway" in which one anticipates diffi­ culry with BMV, EGO use, laryngoscopy and intubation, or cricothyrotomy? If neither of these two situations exists, then RSI is the method of choice. Has a "Failed Airway" supervened?

This systematic approach to airway management in the ED takes into account all possible presentations, and properly iden­ tifying the rype of airway situation permits the practitioner to select an appropriate course of action. Algorithms that address these situations are "expeditious management strategies" often used in crisis and are described in Chapter 2 .

S U M MARY RSI by emergency practitioners is associated with a high rate of success and low incidence of complication. However, some patients should not be paralyzed and to successfully manage their airways will require alternative procedures, such as an "awake intubation." The current challenge then is how to iden­ tify these patients in whom intubation or ventilation with bag­ mask or extraglottic devices would not suffice. In the case presented here, the emergency physician rec­ ognized that the patient was in need of immediate airway control. It was recognized that there were multiple factors that would complicate and make management of the air­ way very difficult. For example, the tissue loss noted on the face would make for very difficult face-mask ventilation, should that become necessary during the intubation attempt. Likewise, the presence of the hematoma in the neck with deviation of the larynx might make rescue oxygenation with an EGO ineffective or not possible at all. A surgical airway might also be technically challenging due to the distorted anatomy seen in the anterior neck. Although laryngoscopy and intubation were not anticipated to be particularly dif­ ficult, this was considered a high-risk airway because rescue oxygenation would likely be very difficult, in the event of a failed intubation attempt. Thus it was felt by the practitio­ ner that the patient was not a safe candidate for RSI . The decision was made to perform an awake intubation using a rigid video-laryngoscope. Before this was attempted, the patient was set up for a potential surgical airway and had his cricothyroid membrane identified and marked. A surgi­ cal airway kit was readied and placed at the bedside. Topical lidocaine was applied to the oropharynx and ketamine 40

mg was given IV. Using a GlideScope the airway was easily visualized and the patient was successfully intubated on the first attempt. Immediately after the intubation, the patient was sedated with propofol and paralyzed with rocuronium to minimize the risk of accidental extubation while the patient was been further evaluated and managed.

REFERENCES 1. Benumof J. The ASA difficult airway algorithm: new thoughts and con­ siderations. 5 1 st Annual Refresher Course Lectures and Clinical Update Program, #23 5 . American Society of Anesthesiologists; 2000. 2. Daya M, Mariani R, Fernandes C. Basic life support. In: Dailey R, Simon B, Young G, Stewart R, eds. The Airway: Emergency Management. Philadelphia, PA: Mosby; 1 992:39-6 1 . 3 . Safar P. Ventilatory efficacy o f mouth-to-mouth artificial respiration; air­ way obstruction during manual and mouth-to-mouth artificial respiration. } Am MedAssoc. 1 95 8 ; 1 67:33 5-34 1 . 4 . Safar P, McMahon M . Mouth-to-airway emergency artificial respiration. } Am MedAssoc. 1 95 8 ; 1 66: 1 459- 1 460. 5 . Safar P. History of cardiopulmonary resuscitation. Acute Care. 1 986; 1 2 : 6 1 -2. 6. Walls R. Airway. In: Marx J, Hockberger R, Walls R, eds. Rosens Emergency Medicine: Concepts and Clinical Practice. Philadelphia, PA: Mosby; 2009:2-20. 7. Murphy M, Walls RM . Identification of the difficult and failed airway. In: Walls RM , Murphy MF, eds. Manual of Emergency Airway Management. 3rd ed. Philadelphia, PA: Lippincott, Williams, Wilkins; 2008: 8 1 -93.

SELF - EVALUATION QU ESTIONS 22. 1 . All o f the following are indications for emergency tra­ cheal intubation EXCEPT A. upper airway obstruction B. failure to protect the airway C. failure to maintain reasonable oxygen saturations D. the need for hyperventilation E. cardiac arrest 22.2. Responsibiliry for ensuring appropriate airway manage­ ment in the ED A. rests with the most highly trained practitioner in the room B. rests with the anesthesia practitioner, if present C. is often unclear D. rests primarily with the emergency practitioner of record E. should be negotiated at the time 22. 3 . An unconscious 1 9-year-old morbidly obese male is brought in to the emergency department (ED) by Emergency Health Services (EHS) paramedics, having been found unresponsive at a fraterniry initiation parry. He had been drinking heavily, although the amount of alcohol consumed is unknown. The patient is uniden­ tified and there is no available past medical history.

329

330

Ai rway M a n a g e m e n t i n the E m e rg e n cy Room

Respirations are shallow, and paramedics have inserted a nasal trumpet and an oral airway and are assisting ven­ tilations with a bag-mask. They had attempted oral and nasal intubation three times in the field but failed due to the patient being combative and obesity. All of the fol­ lowing are acceptable strategies to employ in managing this airway EXCEPT A. moving the patient to the OR for airway management B. intubating "earlier rather than later"

C. performing an awake look, then backing off to per­ form RSI D. intubating awake even if you sense that you can para­ lyze the patient and be successful at intubation E. delaying airway management at all costs until an anesthesia practitioner is present

331

C H A PT E R 2 3

Patient with Dead ly Asth ma Requires Intubation Kerryann B. Broderick and Jen nifer W. Zhan

CAS E PRESE NTATION

331

PAT I E NT EVALUATI ON

331

AI RWAY EVALUATION A N D MANAG EMENT OPTIONS . 332 ADDITIONAL CO N S I D ERATIONS . . . . . . . . . . . . . . . . . .

334

S U M MARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

335

SELF-EVALUATIO N Q U ESTI O N S . . . . . . . . . . . . . . . . . . . 336

CASE PRESENTATION Emergency Medical Service (EMS) presents with a 26-year-old male who is agitated and combative, in severe respiratory dis­ tress. Per EMS report, he has a history of asthma, and bystand­ ers found him in severe respiratory distress after using crack cocaine. He has been intubated in the past for his asthma, often triggered by cocaine use, most recently 2 months ago during which he spent a week in the intensive care unit (ICU) . He arrives at the emergency department (ED) after an EMS trans­ port of 1 5 minutes during which he has been receiving contin­ uous aerosolized albuterol via a nebulizer. He required restraints en route, is screaming in one- to two-word sentences on arrival, and is thrashing around the bed. He is 5 ' 2" ( 1 57 em) tall and weighs 1 65 lb, with a BMI 30.5 kg·m - z . His vital signs are: respiratory rate 24 breaths per min­ ute, heart rate 1 34 beats per minute, and blood pressure 1 1 0/60 mm Hg. He is diaphoretic and using his accessory muscles. His oxygen saturation is 89% on 1 5 Lmin-1 of oxygen via a non­ rebreather and he is quickly becoming fatigued. You notice he has a scar on his neck from a prior cricothyrotomy and a steroid body habitus with an edematous face and short neck.

PATI ENT EVALUATION • What Are Th is Patient's Vita l Organ

System Reserves?

CNS reserve: There is nothing to indicate that this patient will respond abnormally to standard doses of induction agents, keeping in mind that he is obese and should be dosed accord­ ingly. The patient is agitated and confused on arrival, which may be a consequence of crack cocaine use as well as carbon dioxide retention, in which case sensitivity to sedative hypnotic induction agents ought to be anticipated. Cardiovascular reserve: This is a young patient who should theoretically have adequate cardiac reserve and normal sys­ tolic and diastolic cardiac function. Cocaine may stun the myocardium in high doses and cause sodium channel block­ ade. Respiratory acidosis can potentiate myocardial depression associated with anesthesia induction agents. Depending on the length of time he has been acutely ill and how adequate his oral fluid intake has been, he could also be relatively volume depleted. In combination with a decrease in venous return sec­ ondary to air trapping and auto-PEEP (positive end-expiratory pressure) seen with acute asthma, the presence of hypovolemia can precipitate a significant hypotension, particularly if induc­ tion agents are used to facilitate intubation.1 The patient has been receiving a large amount of albuterol, a medication with significant 13 z -agonist properties. 13 -agonists cause intracellu­ 2 lar shifting of potassium, which may lead to hypokalemia and arrhythmias. 2 The combination of stress, respiratory acidosis, and large amounts of albuterol use can increase this patient's risk of arrhythmias. When choosing induction agents, it is important to keep in mind that they all have negative inotropic properties for this patient. Respiratory reserve: Patients with severe asthma have pro­ longed expiratory phases and air trapping.3 Peak flow and forced expiratory volume in 1 second (FEV ) may be used to 1

332

Ai rway M a n a g e m e n t i n the E m e rg e n cy Room

assess the degree of airway obstruction and to monitor improve­ ment with treatment. Tidal volumes are limited, with minimal or no respiratory reserve. Substantial ventilation-perfusion mismatch is present, which limits the ability to oxygenate and denitrogenate the lungs prior to induction. Ventilation support may be necessary in severe asthma as these patients become significantly fatigued and unable to maintain gas exchange on their own. Ventilation support may be provide mechanically, requiring intubation or noninvasively by mask using noninva­ sive positive pressure ventilation (NPPV) . These patients are at risk for rapid oxygen desaturation and worsening hypercapnea as apnea ensues as part of a rapid sequence intubation (RSI) . But, the real challenge in managing the severe asthmatics occurs in the post-intubation phase.

AI RWAY EVALUATION A N D MANAGEMENT OPTIONS • Employi ng the Mnemon ics Suggested

in Chapter 1 , Does This Patient Have a Difficult Airway?

Yes! Facial and neck edema from chronic steroid dependence may make bag-mask-ventilation (BMV) difficult. In addition, this patient is obese and in status asthmaticus, both of which are associated with very high airway pressures that can be dif­ ficult or impossible to overcome with a positive pressure BMV Other than these factors, there appear to be no other predictors of a difficult BMV when applying the mnemonics MOANS (see section "Difficult BMV: MOANS" in Chapter 1 ) . While the LEMON mnemonic (see section "Difficult DL Intubation: LEMON" in Chapter 1) suggests that neck and face edema may make direct laryngoscopy difficult, there are no predictors of difficult use of video-laryngoscopes (CRANE, see section "Difficult VL intubation: CRANE" in Chapter 1 ) . Subglottic stenosis i s important t o consider i n this patient as he has experienced many tracheal intubations in the past, in con­ junction with corticosteroid use and mechanical ventilation. However, the geometry of his upper airway appears normal, and he has a Mallampati Class II airway. His neck appears to be freely mobile. Another mnemonic to assist the assessment of the feasibility of using an extraglottic device (EGO) is RODS (see section "Difficult Use of an EGO: RODS" in Chapter 1 ) . Restricted mouth opening is not an issue in this patient and upper airway obstruction is only a possibility. However, he has severe obstruc­ tive lung disease and his compromised pulmonary compliance, the "stiffness of the lungs," will seriously limit usefulness of an EGO just as BMV may be difficult. There are several indicators of a potentially difficult airway in this patient, and he may not be an optimal candidate for an RSI. A failed intubation in a hypoxemic person with very poor lung compliance would be a very dangerous situation. A surgi­ cal airway may be difficult in this patient since he has a history of a cricothyrotomy and redundant neck tissue (SHORT, see section "Difficult Cricothyrotomy: SHORT" in Chapter 1 ) . Th e decision to perform RSI should b e i n the context o f the experience of the practitioner as well as the device(s) being used

and availability of backup. For instance, the use of RSI may be very different if the practitioner is using a video-laryngoscope versus a standard laryngoscope. • What Other Airway Concerns That You Have

for Th is Patient?

This patient has no respiratory reserves, rapid oxygen desatu­ ration, hypotension, and possible subglottic stenosis. The insertion of a tracheal tube in a person who is already in bron­ chospasm may exacerbate his condition. • Have We Medica lly Optim ized His Treatment

Prior to Tracheal I ntubation?

Patients should receive continuous supplemental oxygen to keep 02 saturations above 90%. Short-acting 13 z -agonists are the mainstay of treatment in asthma, via a nebulizer or metered dose inhaler.4 Long-acting 13 z -agonists have a longer onset of action of at least 20 minutes and are not an effective rescue medication. This patient has already been on continuous bronchodilators for the 1 5-minute transport and is receiving supplemental oxygen via a non-rebreather. The addition of cor­ ticosteroid is recommended for patients with an acute moderate to severe exacerbation of asthma,5 although the delayed onset of action for corticosteroids (onset within a few hours, peak effect around 24 hours) will not be helpful in avoiding intubation in the immediate/emergency period. Since there is no evidence to suggest that IV steroid has an advantage over the oral route, oral steroids should be administered unless the patient is not tolerating the oral route. For reasons already outlined, avoiding intubation would be the best option if possible. • What Additional Medical Therapeutic

Options Are Available to This Patient?

Anticholinergics: Meta-analysis suggests that there is a modest benefit in adding this therapy to 13-agonists.6 Antagonizing cholinergic effects at muscarinic receptors can reduce smooth muscle contraction and the release of secretion at large air­ ways. The use of anticholinergics such as ipratroprium bromide reduces hospital admission rates (30%-60%, NNT 5-1 1 ) ? Magnesium: Two meta-analysis have been performed ana­ lyzing the effect of IV magnesium on patients with asthma. 8·9 Seven trials were identified and the investigators conclude that magnesium has no confirmed role in the management of mild or moderate asthma. In severe asthma, there is evidence that magnesium improves pulmonary function and decreases hospi­ talization rates, although there is no good evidence that magne­ sium decreases the need for intubation in patients with severe asthma. Magnesium is unlikely to cause harm. However admin­ istration should not delay intubation or any other therapy. Noninvasive ventilatory support (NIVS): One randomized trial and several small uncontrolled trials support the use of NIVS in acute asthma. 10-14 NIVS has been demonstrated to improve expiratory Bow rates and reduce the need for hospi­ talization, although a recent meta-analysis by Ram et al. 1 5 con­ cluded that routine use of NIVS in severe acute asthma could not be recommended. Patients who have an alert mental status

Patient with Dea d l y Ast h m a Req u i res I ntu bation

and intact airway reflexes may be good candidates to trial NIVS before considering intubation. The patient in this case is unco­ operative and combative so we need to consider intubation instead. • What Are the Possible Options Regarding

Airway Management in This Patient?

A trial of NIPPY could be considered. This patient is very uncooperative and therefore would require sedation. A trial of ketamine at lower doses and NIPPY could be considered very carefully. In one study, this was used to denitrogenate patients but it was found that a few patients were able to tol­ erate NIPPY after the low-dose ketamine and intubation was averted. 16 In this particular group of patients, and despite the reservations that have been mentioned, RSI by a skilled practi­ tioner is probably the best choice. Planning ahead is crucial, as is deciding on a Plan B and C in the event Plan A should fail. While recognizing the limitations of denitrogenation prior to tracheal intubation (described above) , the practitioner should administer as high an oxygen concentration as possible to the patient, employing a bag-mask unit if the patient can tolerate its use. Use of nasal cannula during the apneic phase has been shown to delay desaturation. 16' 17 This should be applied prior to induction and left on during the peri-intubation phase. As an added advantage, the practitioner can provide gentle assisted ventilation to the patient if he is able to tolerate it, taking care not to cause insuffiation of the stomach, vomiting, or gagging. Rapid sequence induction drugs chosen should be administered to the patient while he remains in a comfortable position, in this patient most commonly sitting upright. Once the patient loses consciousness, the patient can be placed in the supine position for laryngoscopy and intubation. A large, 8 .0-mm ID or larger, endotracheal tube (ETT) is preferred in order to reduce resistance and facilitate aggressive pulmonary toilet. However, given patient's prior history of multiple intubations and cricothyrotomy, a series of smaller sized ET tubes should be available in anticipation of potential airway stenosis. Lidocaine dosed at 1 . 5 mg·kg- 1 has been used to attenuate the reflex bronchospasm in response to airway manipulation and to decrease arrhythmias during intubation. 18-20 However, the effectiveness of lidocaine has varied among studies. 2 1 The rec­ ommendation to use IV lidocaine in RSI protocols for the severe asthmatic is extrapolated from the results of studies employing healthy volunteers with a history of bronchospastic disease. 21-24 However, in a prospective, randomized, double-blind, placebo­ controlled trial of 60 patients, lidocaine and placebo groups did not have significantly different transpulmonary pressure and airflow immediately after intubation and at 5-minute inter­ vals. 2 5 Given that there is no established evidence that lidocaine improves long-term outcomes, its use is provider dependent. Ketamine is generally considered to be the induction agent of choice in the asthmatic patient because it increases circulat­ ing catecholamines and inhibits vagal outflow. In addition, it is a direct smooth muscle dilator that does not cause histamine release. 26 While case reports of dramatic improvement in pul­ monary function with ketamine have driven its popularity, 27•2 8 no randomized studies have been performed to demonstrate

ketamine's superiority over other induction agents. In a case series, 1 9 of 22 asthmatic patients with active wheezing had a decrease in bronchospasm during ketamine-induced anesthe­ sia. 2 9 In one prospective, placebo-controlled, double-blind trial of 14 mechanically ventilated patients with bronchospasm, the seven patients treated with 1 .0 mg·kg- 1 ketamine had a sig­ nificant improvement in oxygenation but no improvement in PC0 or lung compliance. In addition, the outcome (discharge 2 from the ICU) was the same in both groups. The study popula­ tion was heterogeneous, making valid conclusions of the benefit of ketamine difficult.30 A randomized, double-blind, placebo­ controlled trial of low-dose IV ketamine, 0.2 mg·kg- 1 bolus followed by an infusion of 0 . 5 mg·kg- 1 ·h- I , in non-intubated patients with acute asthma failed to demonstrate a benefit in IV ketamine.31 Although evidence is limited, at the present time, based on its mechanism of action and safety profile, ketamine appears to be the best agent available for RSI in the asthmatic. Intravenous ketamine 1 . 5 mg·kg -1 should be given immedi­ ately before the administration of 1 . 5 mg· kg -1 of succinylcho­ line. Ketamine may have central sympathomimetic effects and this should be carefully considered in patients with cardiac isch­ emic, intracranial injury, or elevated intraocular pressures. In these patients, etomidate may safely be used as an alternative induction agent. Delayed sequence intubation (DSI) can also be considered. In contrast to RSI, DSI allows for the administration of seda­ tives and denitrogenation before the administration of a para­ lytic agent and intubation. One prospective observational case series studied DSI in patients who were spontaneously breathing and did not tolerate denitrogenation. The patients in this study were given an initial dose of ketamine at 1 mg·kg- 1 followed by 0 . 5 mg·kg- 1 boluses until patients were dissociated. The study concluded that DSI allowed denitrogenation and significant improvement in oxygen saturation in patients who did not tol­ erate oxygenation with traditional methods (BVM, NIPV, etc.). In agitated patients similar to the one in the case above, DSI may provide an opportunity for sedation and oxygenation that might eliminate the need for intubation if the patient improves or simply increase oxygenation prior to intubation. • How Would You I ntubate the Trachea

of This Patient?

1. Pre-Procedure Preparations: The following difficult airway devices should be ready if available: •

•

•

•

an Eschmann Tracheal Introducer (also known as gumelastic bougie) a fiberoptic or video-laryngoscope if available a cricothyrotomy kit an EGD, or an intubating LMA'" The following drugs should be available:

•

•

•

•

ketamine at 1 to 2 mg·kg- 1 succinylcholine at 1 . 5 to 2 mg·kg- 1 Rocuronium 1 .2 mg·kg- 1 sedation and paralytic agents for post-intubation management

333

334

Ai rway M a n a g e m e n t in the E m e rg e n cy Room

2 . Cardiac monitors are applied along with pulse oximetry. Denitrogenation is achieved using high-flow oxygen with the patient sitting. 3. Ketamine is administered IV and the patient is observed until unconscious. This should take 1 to 2 minutes. 4. Succinylcholine (or rocuronium if there are contraindica­ tions to succinylcholine use) is administered. The patient is placed supine with the head and neck placed in a "sniffing" position. Cricoid pressure may be applied by an assistant. The patient is observed for fasciculations. 5. Laryngoscopy is performed. The cords are visualized easily and the ETT is passed and secured. 6. Capnography is used to confirmed correct tracheal placement. 7. Post-intubation drugs are administered for sedation and paralysis.

ADDITIONAL CON S I D E RATIONS • What Are the Appropriate Ventilator

Settings for Th is Patient Following Tracheal Intubation?

All asthmatic patients have obstructed small airways and dynamic alveolar hyperinflation with varying amounts of end­ expiratory residual intra-alveolar gas and pressure (auto-PEEP or intrinsic PEEP) . Elevations in auto-PEEP increase the risk for barotrauma. Reversal of airflow obstruction and decompres­ sion of end-expiratory filled alveoli are the primary goals of early mechanical ventilation in the asthmatic. The former requires continuous in-line nebulization with increasingly higher doses of !3 -agonists until reversal is objectively measured (decrease in 2 peak and plateau airway pressures) or unacceptable side effects are produced. Safe, uncomplicated alveolar decompression requires a prolonged expiratory time (I:E of 1 :3 to 1 : 5 ) . This is achieved by using smaller tidal volumes than usual, with a high inspiratory flow (IF) rate to shorten the inspiratory cycle time and permit a longer expiratory phase.3 2•33 The initial goal of ventilator therapy in the asthmatic patient is to improve arterial oxygen tension to adequate levels without inflicting barotrauma on the lungs or increasing auto-PEEP. Initial tidal volume should be reduced as necessary, to avoid barotrauma and air trapping. The speed at which a mechanical breath is delivered in liters per minute, typically 60 Lmin - 1 , is called the IF rate. In asthma, the initial IF should be increased to 80 to 1 00 L min- 1 with a decelerating flow pattern. A pres­ sure control paradigm is preferred over volume control. If volume control is chosen, the ideal waveform is one of decelera­ tion rather than constant (square) . The ventilation rate should be relatively low in order to allow sufficient time for alveolar decompression. It is acceptable to permit the maintenance or gradual development of hypercapnia through reduced minute ventilation, as this reduces the potential for barotrauma. High intrathoracic pressure caused by air trapping may compromise cardiac output and produce hypotension and therefore should be avoided.34•35 The highest measured pressure at peak inspiration is the peak inspiratory pressure (PIP) . The compliance of the lungs,

chest wall, ventilatory circuit, and ventilator; the resistance of the ETT; and the effect of mucous plugs all contribute to the PIP. This reading has an inconsistent predictive value for baro/volutrauma but ideally should be kept under 50 em H 0. 2 A sudden rise in PIP should be interpreted as indicating tube blockage, mucus plugging, or pneumothorax until proven oth­ erwise. A sudden, dramatic fall in PIP may indicate extubation. The measured intra-alveolar pressure during a 2- to 4-sec­ ond end inspiratory pause is referred to as the plateau pressure (Pplar) . Values less than 30 em H 0 are recommended in order 2 to avoid baro/volutrauma. Measurement and trending of Pplar are excellent objective tools to confirm optimal ventilator set­ tings and the patient's response as well as the reversal of airflow obstruction. If initial ventilator settings disclose a Pplar of more than 30 em H 0, consider lowering minute ventilation and 2 increasing IF, both of which will prolong expiratory time and attenuate hyperinflation. If Pplar is unavailable, PIP may be used as a surrogate. Most patients in status asthmaticus who require intubation are initially hypercapnic. The concept of controlled hypoventi­ lation (permissive hypercapnia) promotes gradual development (over 3 to 4 hours) and maintenance of hypercapnia (PC0 2 up to 90 mm Hg) and acidemia (pH as low as 7.2) . This is done primarily to decrease the risk of ventilator-related lung injury and prevent hemodynamic compromise as a result of increasing intrathoracic pressure from auto-PEEP or intrinsic PEEP (PEEPJ . Permissive hypercapnia is usually accomplished by reducing minute ventilation, increasing IF rate to 80 to 1 00 L min-\ and paralyzing and heavily sedating (usually paralyz­ ing) patients who otherwise would not tolerate these settings. Permissive hypercapnia may be instrumental in promoting prolonged expiratory times and reducing auto-PEEP.36 Lung­ protective tidal volumes should be used for all patients receiv­ ing mechanical ventilation, and FI0 should be decreased as 2 soon as possible to a goal of less than 60%.37 • What Are the I n itial Venti lator Settings for

Th is Patient?

1 . Determine the patient's ideal body weight. 2. Set a tidal volume of 6 to 8 mL·kg- 1 with an Fi0 of 1 .0 2 ( 1 00% oxygen) .33 3. Set a respiratory rate of 8 to 10 breaths per minute. 4. Set an inspiratory to expiratory ratio of 1 :3 to 1 : 5 . Pressure control is preferred. If using the pressure control, the I:E ratio is adjusted directly by the I:E ratio parameter, or by adjusting the inspiratory time parameter. If using volume control, the I:E ratio can be adjusted by increasing the peak flow rate, and the "ramp" inspiratory waveform should be selected. Peak IF can be as high as 80 to 1 00 L·min - 1 • 5 . Measure and maintain the plateau pressure a t less than 30 em H 0 or try to keep PIP at less than 50 em H 0. 2 2 6. Focus on the oxygenation and pulmonary pressures initially. If necessary, allow maintenance or gradual development of hypercapnia to avoid high plateau pressures and increasing auto-PEEP. 7. Assure continuous sedation with a benzodiazepine and paral­ ysis with a non-depolarizing muscle relaxant. The practitioner

Patient with Dea d l y Ast h m a Req u i res I ntu bation

may consider a continuous ketamine infusion for sedation and potential smooth muscle relaxation. 8 . Continue in-line 13 -agonist therapy and additional phar­ 2 macologic adjunctive treatment based on the severity of the patient's illness and objective response to treatment.

• What Is the Utility of U ltrasound in Airway

Management?

Bedside ultrasound can be a useful modality for trained clinicians to confirm ETT placement, evaluate for pneumo­ thorax, or to identify the cricothyroid membrane prior to performing a cricothyrotomy. To confirm ETT placement with ultrasound guidance, apply the linear transducer in a transverse plane above the suprasternal notch with the indi­ cator pointed toward the patient's right. The esophagus has concentric layers and is located left and posterolateral to the trachea. Since the air in the tracheal lumen does not trans­ mit ultrasound waves, the lumen of the trachea is difficult to visualize. Therefore, the esophagus can be visualized on ultrasound during tube advancement to ensure that the tube does not pass through the esophageal lumen.38 Ultrasound can also be helpful in ruling out a pneumothorax after intubation39 or identifying the cricothyroid membrane. To identify the cricothyroid membrane, the linear transducer is placed in the midline anterior neck with the indicator pointing toward the patient's head. Tracheal rings are a series of hyper­ echoic circles that can be visualized in this view. By moving the transducer cephalad, one can see the hypoechoic cricoid and thyroid cartilages which are the boundaries of the cricothyroid membrane.40

S U M MARY The patient with severe asthma constitutes a difficult airway even without anatomical features that might predict difficult laryngoscopy or intubation due to the fact that BVM and EGO rescue may be difficult or impossible. Initial medical manage­ ment options include 13 -agonists, anticholinergics, cortico­ 2 steroids, magnesium, and NIPV If intubation is necessary, a cuffed ETT in the trachea is essential to permit adequate posi­ tive pressure ventilation. Alternative rescue techniques, such as employing non-cuffed tracheal devices, transtracheal jet ventila­ tion, non-cuffed Seldinger cricothyrotomy devices, etc., may be difficult or ineffective. The practitioner should consider ketamine for RSI or DSI. A continuous infusion of ketamine may be of use following intubation. Post-intubation hypotension ought to be expected and managed aggressively with fluids and vasopressors if indi­ cated, recognizing that tension pneumothorax may be a cause of precipitous hemodynamic change. Ventilation strategies ought to include low volumes and respiratory rates with long expiratory times and slow peak IF rates. Arterial carbon dioxide levels are not of immediate concern, provided the arterial pH can be maintained at a level consistent with reasonable cardiac, liver, and renal function.

REFERENCES I . Horak J, Weiss S. Emergent management of the airway. New pharma­ cology and the control of comorbidities in cardiac disease, ischemia, and valvular heart disease. Crit Care Clin. 2000; 1 6 :4 1 1 -427. 2. Bodenhamer J, Bergstrom R, Brown D, et a!. Frequently nebulized beta-agonists for asthma: effects on serum electrolytes. Ann Emerg Med. 1 992;2 1 : 1 337-1 342. 3 . Hall J, Schmidt G, Wood L. Principles of Critical Care. 2nd ed. New York, NY: McGraw-Hill; 1 998. 4. National Heart, Lung, and Blood Institute. National Asthma Education and Prevention Program (NAEPP) , Expert Panel Report 2: Practical Guide for the Diagnosis and Management of Asthma. In: U.S. Department of Health and Human Services, Public Health Services, ed. National Institutes of Health Publication No. 97-4053; 1 997. 5 . Levy BD, Kitch B, Fanta CH. Medical and ventilatory management of status asthmaticus. Intensive Care Med. 1 998 ;24: 1 0 5- 1 1 7. 6. Stoodley RG, Aaron SO, Dales RE. The role of ipratropium bromide in the emergency management of acute asthma exacerbation: a metaanalysis of randomized clinical trials. Ann Emerg Med. 1 999;34:8- 1 8 . 7 . Rodrigo GJ, Rodrigo C. Th e role o f anticholinergics i n acute asthma treat­ ment: an evidence-based evaluation. Chest. 2002; 1 2 1 : 1 977- 1 987. 8 . Alter HJ, Koepsell TD, Hilty WM. Intravenous magnesium as an adjuvant in acute bronchospasm: a meta-analysis. Ann EmergMed. 2000;36: 1 9 1 - 1 97. 9. Rowe BH, Bretzlaff JA, Bourdon C, Bora GW, Camargo CA Jr. Intravenous magnesium sulfate treatment for acute asthma in the emer­ gency department: a systematic review of the literature. Ann Emerg Med. 2000;36: 1 8 1 - 1 90. 10. Carson KV, Usmani ZA, Smith BJ. Noninvasive ventilation in acute severe asthma: current evidence and future perspectives. Curr Opin Pu!m Med. 2 0 1 4;20: 1 1 8- 1 23. 1 1 . Ganesh A, Shenoy S, Doshi V, Rishi M, Molnar ] . Use of noninvasive ventilation in adult patients with acute asthma exacerbation. Am J Ther. 20 1 5 ;22:43 1 -434. 12. Garpestad E, Brennan J, Hill NS. Noninvasive ventilation for critical care. Chest. 2007; 1 32:7 1 1 -720. 1 3 . Pallin M, Hew M, Naughton MT. Is non-invasive ventilation safe in acute severe asthma? Respirology. 20 1 5 ;20:25 1 -257. 1 4 . Pallin M, Naughton MT. Noninvasive ventilation in acute asthma. J Crit Care. 20 1 4;29: 5 8 6-593. 15. Ram FS, Wellington S, Rowe BH, Wedzicha JA. Non-invasive positive pressure ventilation for treatment of respiratory failure due to severe acute exacerbations of asthma. Cochrane Database Syst Rev. 2005 :CD004360. 16. Weingart SO, Trueger NS, Wong N, et a!. Delayed sequence intubation: a prospective observational study. Ann Emerg Med. 20 1 5 ;6 5 : 349-3 5 5 . 1 7 . Ramachandran SK, Cosnowski A , Shanks A , Turner CR. Apneic oxy­ genation during prolonged laryngoscopy in obese patients: a random­ ized, controlled trial of nasal oxygen administration. J Clin Anesth. 2 0 1 0;22: 1 64- 1 68. 18. Gal TJ. Bronchial hyperresponsiveness and anesthesia: physiologic and therapeutic perspectives. Anesth Ana/g. 1 994;78 : 5 5 9-573. 1 9. Gold M. Anesthesia, bronchospasm, and death. Semin Anesth. 1 989;8:29 1 -306. 20. Walls RM . Lidocaine and rapid sequence intubation. Ann Emerg Med. 1 996;27: 528-529. 2 1 . Lev R, Rosen P. Prophylactic lidocaine use preintubation: a review. J Emerg Med. 1 994; 1 2:499-506. 22. Downes H, Gerber N, Hirshman CA. I.V lignocaine in reAex and allergic bronchoconstriction. Br J Anaesth. 1 980;52: 873-878. 23. Groeben H, Foster WM, Brown RH . Intravenous lidocaine and oral mexi­ letine block reAex bronchoconstriction in asthmatic subjects. Am j Respir Crit Care Med. 1 996; 1 54:885-888. 24. Groeben H, Silvanus MT, Beste M, Peters J. Both intravenous and inhaled lidocaine attenuate reA ex bronchoconstriction but at different plasma con­ centrations. Am ] Respir Crit Care Med. 1 999; 1 5 9 : 530-5 3 5 . 2 5 . Maslow AD, Regan M M , Israel E, e t a!. Inhaled albuterol, but not intra­ venous lidocaine, protects against intubation-induced bronchoconstriction in asthma. Anesthesiology. 2000;93: 1 1 98- 1 204. 26. Huber FC Jr, Gutierrez J, Corssen G . Ketamine: its effect on airway resis­ tance in man. South Med j. 1 972;65: 1 1 76 - 1 1 80. 27. LHommedieu CS, Arens ]]. The use of ketamine for the emergency intuba­ tion of patients with status asthmaticus. Ann Emerg Med. 1 987; 1 6 : 568-57 1 . 28. Rock MJ, Reyes de Ia Rocha S , LHommedieu CS, Truemper E. Use of ketamine in asthmatic children to treat respiratory failure refractory to conventional therapy. Crit Care Med. 1 986; 1 4 : 5 1 4-5 1 6. 29. Corssen G, Gutierrez J, Reves JG, Huber FC Jr. Ketamine in the anesthetic management of asthmatic patients. Anesth Ana/g. 1 972; 5 1 : 588-596.

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Ai rway M a n a g e m e n t i n the E m e rg e n cy Room 30. Hemmingsen C, Nielsen PK, Odorico J. Ketamine in the treatment of bronchospasm during mechanical ventilation. Am J Emerg Med. 1 994; 1 2:4 1 7-420. 3 1 . Howton JC, Rose J, Duffy S, Zoltanski T, Levitt MA. Randomized, double-blind, placebo-controlled trial of intravenous ketamine in acute asthma. Ann Emerg Med. 1 996;27: 1 70- 1 7 5 . 3 2 . Corbridge TC, Hall J B . Techniques for ventilating patients with obstruc­ tive pulmonary disease. J Crit Illn. 1 994;9: 1 027- 1 036. 33. Leatherman J. Mechanical ventilation for severe asthma. Chest. 20 1 5 ; 1 47: 1 67 1 - 1 680. 34. Tuxen DV. Permissive hypercapnic ventilation. Am j Respir Crit Care Med. 1 994; 1 50: 870-874. 35. Wiener C. Ventilatory management of respiratory failure in asthma. ]AMA. 1 993;269:2 1 28-2 1 3 1 . 36. Bidani A, Tzouanakis AE, Cardenas VJ Jr, Zwischenberger JB. Permissive hypercapnia in acute respiratory failure. ]AMA. 1 994;272:957-962. 37. Mosier JM, Hypes C, Joshi R, et al. Ventilator strategies and rescue thera­ pies for management of acute respiratory failure in the emergency depart­ ment. Ann Emerg Med. 20 1 5;66: 529-54 1 . 38. Muslu B , Sert H , Kaya A, e t al. Use o f sonography for rapid identification of esophageal and tracheal intubations in adult patients. J Ultrasound Med. 20 1 1 ;30:671 -676. 39. Kendall JL, Hoffenberg SR, Smith RS . History of emergency and critical care ultrasound: the evolution of a new imaging paradigm. Crit Care Med. 2007;35:S 1 26-S 1 30. 40. Singh M, Chin KJ, Chan VW, et al. Use of sonography for airway assess­ ment: an observational study. ] Ultrasound Med. 20 1 0;29:79-8 5 .

SELF - EVALUATION QU ESTIONS 23. 1 . Hypotension following RSI facilitated tracheal intuba­ tion of the deadly asthmatic may be due to all of the following EXCEPT A. increased mean intrathoracic pressure associated with positive pressure ventilation B. hypovolemia related pre-presentation

to

reduced

oral

intake

C. acute respiratory acidosis D. reduced systemic succinylcholine

vascular

resistance

due

to

E. an acute tension pneumothorax 23.2. All of the following are true with respect to the phar­ macologic management of asthma in the peri-intubation period EXCEPT A. IV magnesium has been shown to decrease the need for intubation B. antimuscanmcs such as glycopyrrolate have been shown to increase the viscosity of bronchial secre­ tions, increase the incidence of mucous plugging, and should not be used in acute severe asthma C. the evidence clearly supports the use of lidocaine in acute severe asthma D. ketamine is the induction drug of choice in acute severe asthma E. IV magnesium in high doses leads to skeletal muscle weakness. 2 3 . 3 . Which of the following best characterizes the best way to mechanically ventilate an intubated patient with acute severe asthma? A. large tidal volumes and low ventilation rates B. small tidal volumes and low peak flow rates C. large tidal volumes and low peak flow rates D. small tidal volumes and high peak flow rates E. large tidal volumes and high peak flow rates

337

C H A PT E R 2 4

Trachea l Intubation in an Un cooperative Patient With a Nec k Injury Kerryann B. Broderick

CAS E PRESE NTATION

337

I N ITIAL PATI ENT ASSESSM ENT A N D MANAG EMENT . . 337 AI RWAY MANAG E M E NT . . . . . . . . . . . . . . . . . . . . . . . . . 338 OTH ER CO N S I D E RATI O N S . . . . . . . . . . . . . . . . . . . . . . .

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S U M MARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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SELF-EVALUATIO N Q U ESTI O N S . . . . . . . . . . . . . . . . . . . 340

CASE PRESENTATION A 30-year-old male arrives by Emergency Medical Services (EMS) helicopter with a tree branch impaled in his neck (see Figure 24- 1) . It is apparent that substantial force was involved in this impaling injury. He is a healthy lumber-worker in a surrounding mountain area. The injury occurred 4 hours ago, the patient was extri­ cated from the scene and the medics received report that there was a moderate amount of blood at the scene. Shockingly, he is intact neurologically with normal movement and sensation. His airway was intact in-flight but the medics are now report­ ing some increased hoarseness and confusion. They were with him for 2 hours and administered 4 mg of midazolam and 200 meg of fentanyl. He kept pulling off his oxygen so they left it off even though his oxygen saturation was 94% with the oxygen by non-rebreather face mask. They are concerned that he seems to be getting more agitated. The patient denied past medical history, medications, or allergies. The patient is sitting semi-upright in restraints, slightly agi­ tated and appearing very anxious. His vitals are: BP, 1 50/ 1 1 0; HR, 1 30 bpm; RR, 32 breaths per minute, and a pulse oxim­ etry of 90% on room air. He is moderately cooperative for the examination but seems anxious and his voice is definitely hoarse. The neck wound is not pulsatile but there is oozing blood.

I N ITIAL PATI ENT ASSESS MENT A N D MANAG E M E NT • What Are the I m porta nt Considerations in

Eva l uati ng This Patient?

This patient has a suspected penetrating tracheal/esophageal injury as evidenced by his hoarse voice. He is also at signifi­ cant risk for a cervical spine inj ury and has the potential for rapid deterioration to his airway and cardiovascular stability. The most important first step is to get control of the patient. Aggressive initial management is necessary in order to safely care for the patient, for both the team and the patient's sake. Immediate chemical restraint is necessary. The presence of this large impaling foreign body in his neck signals that intubation in the supine position is highly unlikely. Therefore, it is imperative to better evaluate this airway in order to strategize how to proceed with intubation. His hypertension is most likely due to anxiety from the injury. His tachycardia could be due to anxiety as well or blood loss and impending shock. He is a young patient who should have adequate cardio­ respiratory reserves. His initial oxygen saturation is concern­ ing but since he is thrashing around it is unknown how he might respond to supplemental oxygen. He has no other signs of trauma and associated injuries. Therefore, besides his wound, you should have no further complications. • What Are the Airway Priorities in Th is

Patient?

While management of this airway should follow the American College of Surgeons ATLS standards, this airway needs vety spe­ cial attention. 1 Significant considerations for tracheal and cervical injuries are on the list. These potential injuries carty serious con­ cern as blind intubation could completely transect the trachea or cause spinal injury. Should a blind technique be selected, it would only be immediately pre or post arrest as a last ditch effort.

338

Ai rway M a n a g e m e n t i n the E m e rg e n cy Room

AI RWAY MANAGEMENT • What Are the Considerations in Managing

Th is Patient's Airway?

F I G U R E 24- 1 . A patient i s a d m itted to the e mergency department with a tree bra n c h i m pa led i n h i s neck.

Penetrating neck trauma has been a rare but significant cause of injury for centuries. Incidence of penetrating neck injury is closely related to violent crimes and military conflict. In the Unites States in 20 1 3, penetrating neck injuries accounted for less than 2% of all reported injuries with very high fatality. 2 Penetrating neck wounds due to occupational exposures are still case reportable. His MOANS (see section "Difficult BMV: MOANS" in Chapter I) evaluation gives the practitioner the sense that there may well be some difficulty in bag-mask-ventilation. While the patient has a normal appearing face, is not obese, not elderly, without facial hair, and not edentulous, just a visual inspection of the foreign body location is concerning. The pressure gener­ ated by bag-mask-ventilation could potentially dislodge a clot or produce subcutaneous emphysema. Though it is not antici­ pated that mask seal will be an issue, opening the airway with a jaw thrust or chin lift might be impeded by the impaled foreign body. Flexing or extending this patient's neck could possibly move his cervical spine should there be an unstable injury. The airway practitioner should be prepared for bag-mask-ventilation failure. Chemical restraint should be initiated early and aggressively. Options include medications such as midazolam, haloperi­ dol, olanzapine, and ketamine alone or in combination. There is a great deal of literature regarding the safety of chemical restraint.3-6 The first paper to appear in the emergency medicine literature was in 1 987 by Young.6 Many of the studies report that chemical restraint can cause hypoxemia especially when used in combination with other sedatives.7 The most recent studies are on the use of ketamine especially in the pre-hospital setting for agitated delerium.8-1 1 However, this body of litera­ ture centers around either psychiatric conditions or acute drug intoxication, not around agitation due to inj ury and/or por­ tending shock.

This airway is not a crash airway but is definitely a difficult one. Difficulty should be anticipated with both bag-mask­ ventilation and laryngoscopy. RODS (Restricted mouth opening, Obstruction [upper airway] , Disrupted or distorted airway, Stiff lungs or cervical spine) is a mnemonic intended to identifY successful use of an extraglottic device (see section "Difficult Use of an EGD: RODS" in Chapter 1 ) . This patient has normal mouth opening, however, his hoarse voice may sig­ nal edema or distortion, and a potential impending cervical spine injury are strong indicators that a rescue technique using an extraglottic device (EGD) may not be successful. EGDs may not be successful, particularly if the geometry of the hypo­ pharynx is distorted by the injury as EGD seat and seal are hindered. Topical anesthesia coupled with pharmacologic control of the patient may permit the practitioner to perform indirect visualization of the airway with a video-laryngoscope or flexible endoscope (via the mouth or the nose) . This may be of great benefit in planning the airway management strategy. If time allows as in this patient, an awake intubation with a flexible bronchoscope should be performed. The most skilled and experienced practitioner should be at the helm. This may be anesthesia, the emergency physician, or the sur­ geon but reasonable skill with flexible endoscopic intubation is essential. There is still a competing risk of cervical injury and vascu­ lar collapse due to clot dislodgment and serious consideration should be made to taking this patient to the operating room where a possible emergency tracheotomy and/or thoracotomy could be urgently performed to get control of both bleeding and the airway. Depending on the evaluation, ECMO performed in the OR, but contemplated and activated in the ED may be consid­ ered if sudden loss of the airway is judged to lead to a situation that is impossible to rescue by BMV, EGD, direct or indirect laryngoscopy, or even a surgical airway.

• What Are the Indications and

Contra indications for Flexi ble Endoscopic I ntubation?

The primary indication would be when bag-mask-ventilation, use of an EGD, and direct laryngoscopic intubation predicted to be difficult and not certain, and the airway is not a crash air­ way. Bronchoscopic intubation can be done with topical anes­ thesia and sedation in a sitting position preferably in the OR. The patient must be somewhat cooperative and maintaining their airway. See Chapter 3 for a detailed discussion of airway topicalization. Regarding cervical spine injuries, while no intubation tech­ nique has been shown to be clearly superior, 1 2 •13 minimizing neck movement using this technique can be a valuable alterna­ tive and has been used extensively (see Chapters 3 and 1 0) . 14

Tra c h e a l I ntu bation i n a n U n coo perative Patient With a Neck I nj u ry

• Step by Step: What Is the Best Way to

I ntubate Th is Patient's Trachea?

Intravenous medications will probably be needed to facilitate patient's cooperation for the procedure, though small doses of sed­ ative hypnotics like midazolam are associated with sudden, unex­ pected airway obstruction. The practitioner is hoping that the architecture of the airway and the tone of the musculature remain intact. Ketamine is probably the best choice for both chemical restraint, pain, and intubation. If time permits, the addition of glycopyrrolate or other anticholinergic may also be considered to avoid increased salivation/bronchorrhea and coughing. Oxygenation via nasal prongs at 1 0 to 1 5 Lmin- 1 (or the highest flow rate tolerated by the patient) should be adminis­ tered continuously. Consideration should be given to a flexible endoscopic nasal intubation to take advantage of the less acute angle to the larynx compared to the oral approach. While some practitioners consider insufflating oxygen down the working channel of the bronchoscope, this practice is known to be hazardous and may lead to barotrauma and gastric insufflation with rupture if not done at low oxygen flow rates. A double set up for a surgical airway should be prepared. An open thoracotomy tray should be at the bedside and the team should be ready to perform an emergency thoracotomy if the patient decompensates during intubation. Ketamine at 0 . 5 to 1 .0 mg·kg- 1 IV, and topical anesthesia such as lidocaine should be used to decrease the risk of cough during intuba­ tion. The endotracheal tube (ETT) should be loaded onto the flexible bronchoscope if an oral approach is to be employed, or placed in the nostril if the intubation is to be done nasally. The flexible bronchoscope should be gently passed through the glottis and into observing for edema or the tracheal defect and the ETT should be gently advanced over the bronchoscope, asking the patient to take a deep breath as the cords are passed by the advancing tip of the ETT. Taking a deep breath causes involuntary abduction of the cords. • What Is the Utility of U ltrasound in Airway

Management?

Bedside ultrasound can be a useful modality for trained practi­ tioners to confirm ETT placement, evaluate for pneumothorax, or to identifY the cricothyroid membrane prior to performing a cricothyrotomy. To confirm ETT placement with ultrasound guidance, apply the linear transducer in a transverse plane above the suprasternal notch with the indicator pointed toward the patient's right. The esophagus has concentric layers and is located left and posterolateral to the trachea. Since the air in the tracheal lumen does not transmit ultrasound waves, the lumen of the trachea is difficult to visualize. Therefore, the esophagus can be visualized on ultrasound during tube advancement to ensure that the tube does not pass through the esophageal lumen. 15 Ultrasound can also be helpful in ruling out a pneumothorax after intubation16 or identifYing the cricothyroid membrane. To identifY the cricothyroid membrane, the linear transducer is placed in the midline of the neck anteriorly with the indicator pointing toward the patient's head. Tracheal rings are a series of hyperechoic circles that can be visualized in this view. By moving the transducer cephalad, one can see the hypoechoic

cricoid and thyroid cartilages that are the boundaries of the cricothyroid membrane. 17 The use of ultrasound in this patient may or may not be very useful in identifYing the position and course of the upper air­ way and trachea depending on the location of the tree branch impaled in the patient's neck. If the tree branch is lodged super­ ficially and anterior to the airway, no images of the airway can be seen with the ultrasound.

OTH E R CO N S I D E RATIONS • What Are the Concerns With Ventilation and

Post-I ntubation Care?

The most immediate concern is the incitement of bleeding (perhaps massive) or cervical injury. Once the airway is secured, this injury requires vascular, esophageal, and cervical evaluation and this may be done first with a computed tomography angiography (CTA) of the neck. Further investigations can be performed in the operating room with fluoroscopy, endoscopy, or following the neck exploration. Following intubation, as with all difficult airways, the risk of accidental extubation must be addressed through pharmaco­ logic control of the patient (sedatives, opioids, and neuromus­ cular blocking drugs) and securing the device used to manage the airway. Ultimately, a plan for extubation will need to be constructed. (See Chapters 2 and 30 for details.) • What Are the Potential Postsurgical

Compl ications of This Type of I nju ry?

Infectious complications must be anticipated particularly if esophageal violation has occurred leading to oral bacterial con­ tamination of the wound. Tube obstruction due to hematoma, edema, or secretions should be monitored closely. A spinal injury must be ruled out as part of the workup. • Are There Alternatives to Flexible

Endoscopic I ntubation for This Patient and Th is Type of I nju ry in the ED?

Not every emergency department has flexible endoscopes avail­ able or someone skilled in the use of these devices. Alternatives would be to chemically restrain and transport via critical care to a facility that can handle this airway. Performing a crico­ thyrotomy or tracheotomy is a reasonable alternative. Another alternative would be to attempt an awake look with direct or video-laryngoscopy with sedation or attempt an awake­ intubation with a tracheal introducer (bougie) and a small ETT. Calling for assistance early with anesthesia and surgery is the best approach for this patient. Cricothyrotomy or tracheotomy under local anesthesia may well be the best way to proceed for some of these patients.

S U M MARY In summary, this is a very challenging and difficult airway. It is imperative to recognize this and the best approach in

339

340

Ai rway M a n a g e m e n t in the E m e rg e n cy Room

managing this airway is to call for anesthesia and surgery assistance early. The practitioner must recognize the potential inj uries to major vessels, the aerodigestive track, as well as the cervical spine. Tracheal inj uries are rare but lethal inj u­ ries should be approached thoughtfully and cautiously if time allows . 1 8

REFERENCES 1. Nance ML. National Trauma Data Bank Annual Report 2013. American College of Surgeons; 20 1 3 . 2. Panwar A , Meyers AD, e t al. Penetrating injuries o f the neck. Available at: http :/ I emedici ne. medscape.com/ article/8G9 5 79-overview. Accessed March 2, 20 1 G . 3. Coburn VA, Mycyk MB. Physical and chemical restraints. Emerg Med Clin North Am. 2009;27:G55-GG7, ix. 4. Nobay F, Simon BC, Levitt MA, Dresden GM. A prospective, double­ blind, randomized trial of midazolam versus haloperidol versus lorazepam in the chemical restraint of violent and severely agitated patients. Acad Emerg Med. 2004; 1 1 :744-749. 5 . Weiss S, Peterson K, Cheney P, Froman P, Ernst A, Campbell M. The use of chemical restraints reduces agitation in patients transported by emer­ gency medical services. } Emerg Med. 201 2;43: 820-828. G. Young GP. The agitated patient in the emergency department. Emerg Med Clin North Am. 1 987;5 :7G5-78 1 . 7 . Deitch K, Rowden A, Damiron K, Lares C , Oqroshidze N , Aguilera E. Unrecognized hypoxia and respiratory depression in emergency depart­ ment patients sedated for psychomotor agitation: pilot study. WestJ Emerg Med. 20 1 4; 1 5 :430-437. 8. Burnett AM, Peterson BK, Stellpflug SJ, et al. The association between ket­ amine given for prehospital chemical restraint with intubation and hospital admission. Am ] Emerg Med. 20 1 5 ;33:7G-79. 9. Burnett AM, Salzman JG, Griffith KR, Kroeger B, Frascone RJ. The emer­ gency department experience with prehospital ketamine: a case series of 1 3 patients. Prehosp Emerg Care. 20 1 2 ; 1 G:5 53-559. 1 0 . Isbister GK, Calver LA, Downes MA, Page CB. Ketamine as rescue treat­ ment for difficult-to-sedate severe acute behavioral disturbance in the emergency department. Ann Emerg Med. 20 1 G;G7: 5 8 1 -5 87, e l . 1 1 . Scheppke KA, Braghiroli J , Shalaby M , Chait R. Prehospital use o f i.m. ketamine for sedation of violent and agitated patients. West J Emerg Med. 2 0 1 4 ; 1 5 : 73G-74 1 . 1 2. Crosby ET. Airway management i n adults after cervical spine trauma. Anesthesiology. 200G; 1 04: 1 293- 1 3 1 8 . 1 3 . Morris JR. Fibreoptic intubation. Can ] Anaesth. 1 994;4 1 : 996- 1 007. 14. Meschino A, Devitt J H, Koch JP, Szalai JP, Schwartz ML. The safety of awake tracheal intubation in cervical spine inj ury. Can J Anaesth. 1 992;39: 1 1 4- 1 1 7.

1 5 . Muslu B, Sert H, Kaya A, et a!. Use of sonography for rapid identification of esophageal and tracheal intubations in adult patients. J Ultrasound Med. 20 1 1 ;30:G71 -G7G. I G. Kendall JL, Hoffenberg SR, Smith RS . History of emergency and critical care ultrasound: the evolution of a new imaging paradigm. Crit Care Med. 2007;3 5 :S 1 2G-S 1 30. 1 7 . Singh M, Chin KJ, Chan VW, Wong DT, Prasad GA, Yu E. Use of sonog­ raphy for airway assessment: an observational study. J Ultrasound Med. 2 0 1 0;29:79-85 . 1 8 . Schaefer S D . Management o f acute blunt and penetrating external laryn­ geal trauma. Laryngoscope. 2 0 1 4 ; 1 24:233-244.

SELF-EVALUATION QU ESTIONS 24. 1 . Th e mnemonic RODS i s used i n assessing difficulty with which of the following? A. laryngoscopic Intubation B. bag-mask-ventilation C. use of an extraglottic device D. flexible bronchoscopic intubation E. ventilator management 24.2. Regarding chemical sedation as an adjunct to control the airway assessment in the emergency patient which of the following is true? A. should be used in combination with a second agent B. not useful in trauma patients C. can cause hypoxemia D. not indicated in airway management E. only useful in psychiatric patients 24. 3 . Ultrasound can be useful as an adjunct in intubation in all of the following EXCEPT A. diagnose a Pneumothorax B. locate the cricothyroid membrane C. observe tube pass into the trachea D. observe tube pass into the esophagus E. locate the tube in the lower trachea

341

C H A PT E R 2 5

Airway Manage ment for the Burn Patient La eben Lester and Darren Braude

CAS E PRESENTATION

341

PAT I E NT ASSESSM ENT . . . . . . . . . . . . . . . . . . . . . . . . .

341

AI RWAY MANAG E M E NT .

342

POST-I NTU BATION MANAG EMENT . . . . . . . . . . . . . . .

343

S U M MARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

343

SELF-EVALUATIO N Q U ESTI O N S . . . . . . . . . . . . . . . . . . . 343

finger breaths below the hyoid. The Mallampati score is I. The nasal hairs are singed and there is mild erythema to the tongue and posterior pharynx with a small intact blister noted. He has full range of motion of the neck but laryngeal landmarks are difficult to appreciate due to a combination of obesity and burns.

PATI ENT ASSESSMENT • What Are the Airway Eva luation

Considerations in This Patient?

CASE PRESENTATION A 57-year-old man was brought to the emergency department by Emergency Medical Service (EMS) with burns to the head, face, and chest secondary to smoking while on 2 L-min- 1 of oxygen via nasal cannula for COPD. There was no reported loss of consciousness. Albuterol was nebulized, an 1 8-gauge IV was placed and IV fluids and fentanyl administered. Upon arrival to the emergency department, the patient is awake and alert but in obvious pain with mild respiratory distress. He speaks in full sentences with a hoarse voice. His blood pressure is 1 52/9 1 , with a heart rate o f 1 1 2 bpm, breathing 2 6 times per minute, with an oxygen saturation of 97% while receiving oxygen by non-rebreather, and his temperature is 36. 8oC. Lungs sounds are remarkable for diffuse wheezing with fair air movement. The patient is noted to be 6'3 " tall and weighs 1 1 0 kg. Further rapid evaluation reveals deep partial to full thickness burns to the peri-oral region, anterior neck, and upper chest wall. Despite these burns, the patient still has full mouth open­ ing greater than three finger breaths, with a thyromental dis­ tance of three finger breaths and the larynx is more than two

Airway evaluation and management for the acute burn patient builds on standard airway evaluation and management with the added complexities associated with both inhalational and external burns, as well as the potential for coexisting toxicologi­ cal injuries from carbon monoxide and cyanide. In addition, it is critical to consider the potential for the dynamic evolution of inhalational and topical burn injury; an airway initially at low risk for difficulty can progress and become very difficult if edema ensues and leads to obstruction. This patient currently has predictors of moderate difficulty in all four dimensions of airway management: BMV, direct and indirect laryngoscopy, extraglottic device placement, and surgi­ cal airway rescue. The likelihood of toxicological issues is low in this case given there was no prolonged smoke exposure, no loss of consciousness, and mental status is currently normal with relatively reassuring vital signs. • What Are Signs and Sym ptoms of

lnhalationa l l nju ry?

Inhalational injury is a major contributor to the morbidity and mortality associated with burns and is a critical component to the evaluation and management of the airway. Inhalational injury is primarily associated with fires in enclosed space, espe­ cially when there is loss of consciousness. Signs and symptoms

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of inhalational injury may include dyspnea, hoarseness, hot potato voice, stridor, respiratory distress, use of accessory mus­ cles, cough, deep burns to the face or neck, singed nares, car­ bonaceous sputum, and blistering or edema of the oropharynx. Endoscopic evaluation of the upper and/or lower airway is per­ formed in many centers to help with the diagnosis of inhala­ tional injury and to monitor progression. 1' 2 Recently, ultrasonic evidence of tracheal thickening has been used as a marker of inhalational injury.3 • What Is the Time Course for Airway I njury

to Man ifest and Worsen and How Does This I m pact Decisions?

Airway edema can progress early and rapidly or at anytime dur­ ing the first 1 2 to 24 hours, or longer, making airway manage­ ment significantly more difficult.4-6 Likewise, burned skin to the face, neck, and torso can become less elastic, and significant swelling can occur from inflammation and third spacing dur­ ing fluid resuscitation, compounding airway, and ventilation issues. Thus, early intubation has traditionally been emphasized in patients with inhalational injury and may be supported by an increased risk of difficult airway in burned patients intu­ bated in a delayed fashion at burn centers compared to earlier in their course at the initial receiving hospital.6 That said, some have suggested that burn patients are intubated at too high a rate, suggesting more sensitive and specific objective methods of evaluation of the likelihood of progression are needed, such as serial nasopharyngoscopic evaluation?·8 One study based on retrospective data of patients extubated within 2 days of intu­ bation, suggests lower risk of the need for intubation prior to transfer to a burn center when the burns are non-flame injury (such as scald injury) , are not in an enclosed space, are less than 20o/o total body surface area, not third-degree burns to the face, and the distance to the burn center requires less than 3 hours of transfer time.8 When there is concern for inhalational injury and progression of disease, early intubation remains the prag­ matic and recommended approach. • What Add itional Featu res of Burns Can

Affect the Airway?

Burns to lips, cheeks, and neck can effect access to the larynx, making BMV, EGD placement, and laryngoscopy more dif­ ficult. Burns to the neck can impact head positioning, affect­ ing EGD placement, laryngoscopy, and cricothyroidotomy. Likewise, injury and edema to the oropharynx can make BMV, intubation, and EGD challenging. Inj ury to the trachea, bron­ chial tree, and lungs can make oxygenation and ventilation dif­ ficult, and are particularly worrisome in injuries with steam or other super-heated gases. Importantly, chest wall burns can lead to restricted ventilation and may require escharotomy. • What Toxicities Should be Considered?

Common inhalation and fire-related toxicities include carbon monoxide and cyanide. Screening for carbon monoxide can be performed quickly in the emergency department. In gen­ eral, burn victims should be treated with 1 00% oxygen as a

presumptive treatment for carbon monoxide poisoning, while simultaneously allowing for denitrogenation in anticipation of airway management. Cyanide toxicity should be considered in any unconscious patients found in a smoke-filled environment. Empiric therapy with cyanocobalamin should be considered along with toxicology consultation. Additional products of combustion contribute to airway injury but most do not have specific diagnostic tests or antidotes. Intoxication with alcohol and drugs are potential comorbid conditions in burn patients and should be considered, along with vigilance for other ingestions associated with a suicide attempt. • What Other Concerns Do You Have for

Th is Patient?

In this case, there is no suggestion of traumatic inj ury. However, burns associated with blast injuries, vehicle collisions, or other situations involving blunt trauma with the subsequent poten­ tial for spinal and head injuries should be considered early as it may effect airway management. Ongoing or impending hypovolemic shock is an important consideration in the treatment of burn victims and must be considered in choosing induction agents and in preparation for pre- and post-intubation management.

AI RWAY MANAGEMENT • What Are the Pre-Hospital Considerations?

In EMS systems that do not include medication-facilitated airway management in their scope of practice, the decision process for spontaneously breathing patients is quite simple and focuses on BLS airway management and rapid trans­ port, or summoning critical care transport teams when the risk for airway deterioration is considered high and transport times long. Blind nasotracheal intubation may be considered, though has generally fallen out of favor. For EMS teams with the option for medication-facilitated airway management, the thought process and considerations discussed here are relevant. Patients with a strong possibility of inhalation injury or seri­ ous facial burns and/ or long transport times should undergo early intubation when possible, though deferring intubation to the receiving hospital is reasonable in all but the worst cases to insure all the necessary resources for a difficult airway are available. • What Are the Airway Management

Considerations in This Case?

In this patient, anticipation of the potential for increased dif­ ficulty associated with BMV, laryngoscopy, extraglottic devices, and cricothyroidotomy should be considered given the burns to the face, neck, and oropharynx and the potential for inha­ lational injury, as well as the mechanical effects of burns to the chest wall on ventilation. It is likely that this patient will worsen before they get better and early intubation is advised, though nasopharyngeal examination could be considered to exclude injury below the pharyngeal level if it could be performed

Ai rway M a nagement fo r the B u r n Patient

expeditiously. This is not a crash airway and there is time for optimal denitrogenation and preparation. • What Procedu res Should be Used to

I ntubate the Trachea of Th is Patient?

The best choices for airway management in this patient are rapid sequence intubation (RSI) with direct or indirect (video) laryngoscopy if it can be performed before there is further progression of inj ury, or awake intubation. Awake intubation is always a safe choice in such cases and could include endo­ scopic intubation via the mouth or nose, or direct or video­ laryngoscopy of the topicalized patient in the seated position, using techniques described in Chapters 9, 1 0, and 1 1 . A pri­ mary awake cricothyroidotomy or tracheotomy may be con­ sidered but is rarely indicated unless oral and nasal pathology makes these routes inaccessible. In this case, early RSI with video-laryngoscopy was considered to have a high likelihood of success. Given the predicted difficul­ ties, a self-inflating bag with PEEP valve connected as well as an appropriately sized extraglottic device were out and ready and the neck prepared for a surgical airway. Denitrogenation with alb­ utero! nebulizer was utilized throughout the pre-intubation phase as it was maintaining good oxygen saturations. In addition, a nasal cannula was placed to allow for passive oxygenation during the apneic phase of RSI which was performed with ketamine and rocuronium and intubation was successful on the first attempt with no change in the oxygen saturation, with confirmation that included end tidal C0 monitoring. 2 • Are There Unique Pharmacologic

Considerations for the Burn Victim?

It is important to provide adequate analgesia from the outset. Ketamine or etomidate should be considered in the patient with potential or real hypovolemia and hypotension; oth­ erwise any intravenous induction agent would be appropri­ ate. In this case, ketamine may have additional benefits in managing pain and treating the bronchospasm. In burn vic­ tims more than 24 to 48 hours after injury, succinylcholine has been associated with life-threatening hyperkalemia and should be avoided (see section "What Are the Adverse Effects of Succinylcholine and How Can We Minimize These Side Effects?" in Chapter 4) . However, in acute burns, succinyl­ choline is a safe choice for RSI.

to endobronchial sluffing and alveolar edema. Maintenance of a clear endotracheal tube is essential as inspissation of mucous can cause complete obstruction of the endotracheal tube (ETT) and require ETT exchange.9 Assurance of hemodynamic stability is critical and hypoten­ sion should be anticipated in the immediate post-intubation phase as the triumvirate of hypovolemia, sedative drug admin­ istration, and positive pressure can lead to cardiovascular col­ lapse. When hemodynamic stability is assured, post-intubation analgesia and sedation should be administered per local guide­ lines, with consideration of minimizing the risk for ICU delirium. In severe chest wall burns, especially those that are circum­ ferential, escharotomy may be necessary to allow for ventila­ tion. Neck escharotomy may also needed to be performed in very rare situations.

S U M MARY Airway evaluation and management for the acutely burned patient builds on the standard airway approach, adding consid­ eration of possible inhalational injury, external burns, as well as toxicological exposure to the process. Special consideration to the potential for progression of inhalational and topical burn injury is critical in deciding if and when intubation should occur and how to best manage the airway.

REFERENCES 1. Bai C, Huang H, Yao X, et al. Application of flexible bronchoscopy in inhalation lung injury. Diagn Pathol. 2 0 1 3;8: 1 742. 2. Madnani DO, Steele NP, de Vries E. Facrors that predict the need for intubation in patients with smoke inhalation inj ury. Ear Nose 7hroat ]. 2006,85 (4) :278-280. 3 . Kameda T, Fujita M. Point-of-care ultrasound detection of tracheal wall thickening caused by smoke inhalation. Crit Ultrasound]. 20 1 4 ;6 ( 1 ) : 1 1 . 4. Dries OJ, Endorf FW Inhalation injury: epidemiology, pathology, treat­ ment strategies. ScandJ Trauma Resusc Emerg Med. 20 1 3;2 1 :3 1 . 5 . McCall JE, Cahill TJ. Respiratory care o f the burn patient. J Burn Care Rehabil. 2005;26(3) :200-206. 6. Esnault P, Pruner B, Corte J. Tracheal intubation difficulties in the setting of face and neck burns: myth or reality? Am J Emerg Med. 20 1 4;32 ( 1 0) : 1 1 74- 1 1 78. 7. Mackie DP, van Dehn F, Knape P, et al. Increase in early mechanical ven­ tilation of burn patients: an effect of current emergency trauma manage­ ment? J Trauma. 20 1 1 ;70(3) :6 1 1 -6 1 5 . 8 . Romanowski KS, Palmieri TL, Sen S, Greenhalgh DG. More than one third of incubations in patients transferred to burn centers are unnecessary: proposed guidelines for appropriate intubation of the burn patient. J Burn Care Res. 2 0 1 6;37(5 ) : e409-e4 1 4 . 9. Cancio LC. Airway management and smoke inhalation injury in the burn patient. Clin Plast Surg. 2009;36(4) : 5 5 5-567.

POST-I NTU BATION MANAG EM E NT • What Other Issues Should be Considered

Fol lowing Tracheal I ntu bation?

Immediately after intubation is confirmed and the tube secured, attention must be given to breathing, circulation, and maintenance of analgesia and sedation. The patient with inhalational injury is at risk for serious oxygenation and ven­ tilation issues, even without comorbid pulmonary conditions. Bronchospasm may be more common and usually responds to adrenergic fJTagonists. Pulmonary toilet may be necessary due

SELF-EVALUATION QU ESTIONS 2 5 . 1 . Factors associated with challenges i n airway management in patients with acute burns include A. hypovolemia B. inhalational injury C. airway edema D. mechanical effects of burns to the face, neck, and thorax E. all of the above

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25.2. The approach to airway evaluation and management in the burn patient should include A. the standard approach to airway evaluation and management B. intubation for all patients who present with burn injuries C. consideration for potential for coexisting toxicologi­ cal inj uries D. a completely unique approach E. A and C only

2 5 . 3 . Burns to the face, neck, and torso can A. make BMV more difficult B. make EGO placement more difficult C. make laryngoscopy and endotracheal tube placement more challenging D. make surgical airway more challenging E. all of the above

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C H A PT E R 2 6

Airway Manage ment in a Patient with An gioede ma Genevieve MacKinnon, Michael F. Murphy, and David Petrie

CAS E PRESENTATION

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DIAGNOSIS A N D I NVESTIGATIONS . . . . . . . . . . . . . . .

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AI RWAY MANAG E M E NT . . . . . . . . . . . . . . . . . . . . . . . . . 347 S U M MARY . . . .

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SELF-EVALUATIO N Q U ESTI O N S . . . . . . . . . . . . . . . . . .

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CASE PRESENTATION This 25-year-old African American female presents to the emer­ gency department (ED) 2 hours after the onset of lip swelling that has progressed to difficulty in breathing. Her past medical

F I G U RE 26- 1 . Patient with a n g ioed e m a .

history is unremarkable, with the exception of newly diagnosed hypertension. Last week, her primary care physician began a course of a new antihypertensive medication, lisinopril. She has had no previous history of tissue swelling and there is no family history of disorders characterized by tissue swelling. Her ED vital signs are heart rate 1 00 bpm, respiratory rate 22 breaths per minute, blood pressure 1 65/90 mm Hg, temperature 3TC, and Sp0 is 99% on 2 L-min- 1 of oxygen by nasal prongs. 2 The patient is seated (Figure 26- 1) with markedly edema­ tous lips. She has a muffled voice ("hot potato voice") and is unable to swallow her own secretions. There is no stridor. The remainder of the physical examination is within normal limits.

DIAGNOSIS A N D I NVESTIGATIONS • What Is the Pathophysiology of

Angioedema? Are There Different Etiologies?

Angioedema is defined as the abrupt onset of transient, well­ demarcated, non-pitting swelling of the skin, mucous mem­ branes, and deep subcutaneous tissues, including the linings of the upper respiratory and gastrointestinal tracts. 1·3 Angioedema develops because of a local increase in permeability of the sub­ mucosal or subcutaneous capillary vessels, causing local plasma extravasation into the interstitial space.1 . 3 This is exacerbated by the release of vasoactive substances such as histamines, prosta­ glandins, cytokines, and bradykinin.4 Angioedema can be divided into hereditary angioedema (HAE) and acquired angioedema. HAE is extremely rare, affect­ ing in the range of 1 : 30,000 to 1 in 80,000 people.4·5 It devel­ ops due to a C1 esterase inhibitor deficiency, which is inherited in an autosomal dominant pattern with almost complete pen­ etrance.5 This deficiency results in an abnormal increase in the activation of C1 and subsequent excessive formation of the enzyme kallikrein. The excess kallikrein transforms kininogen

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into kinins, including bradykinin. Bradykinin, the primary biologic mediator of angioedema,5 is highly vasoactive and produces the characteristic tissue swelling seen in angioedema.4 HAE is commonly precipitated by trauma and emotional stress. Frequently, the trauma is considered to be minor and can be as innocuous as prolonged sitting on a hard surface or clapping of the hands. Dental and surgical trauma are well-recognized precipitators of an acute attack.5 Patients with known HAE should have a predetermined comprehensive management plan that includes access to treat­ ment in acute attacks and a prophylactic strategy, when indi­ cated, such as prior to elective surgery. Bradykinin-mediated angioedema is not responsive to standard angioedema treatment modalities used for mast cell-mediated anaphylactic angioedema such as corticosteroids, antihistamines, and epinephrine and must be treated with C1 inhibitor replacement and drugs that act on the bradykinin pathway directly.5 Treatment with fresh frozen plasma (FFP) can be beneficial, as it contains C1 esterase inhibitor (C l iNH) . However, FFP can occasionally induce an acute exacerbation of the attack as it contains uncleaved high­ molecular-weight kininogen. Therefore, caution is warranted when using FFP for the treatment of an HAE attack. Three medications are available in the United States that act on the kallikrein-bradykinin pathway directly and been proven to be beneficial in the treatment and prophylaxis of recurrent HAE attacks. These include pasteurized, nanofiltered, plasma-derived C 1 inhibitor concentrate (Berinert) , and bradykinin pathway antagonists (ecallantide and icatibant) . A recombinant human C l iNH (Ruconest) is available in Europe.4.6 Acquired angioedema comprises several types, including: •

•

•

acquired C1 inhibitor deficiency (C l iNH) mediated by bradykinin,5 anaphylaxis mediated by IgE, precipitated by exposure to a previously sensitized allergen (such as antibiotics, peanuts, and shellfish) , and anaphylactoid reactions mediated by direct mast cell degran­ ulation as elicited by agents such as morphine, vancomycin ("red man syndrome") , and radio-contrast media; or by alter­ ing arachidonic acid metabolism as seen in reactions caused by benzoates and nonsteroidal anti-inflammatory agents (NSAIDs) .7•8

Anaphylaxis is characterized by the acute onset of a spec­ trum of effects that may include angioedema of the upper air­ way. Varying degrees of systemic effects manifested by wheeze secondary to bronchoconstriction and hypotension secondary to vasodilation and plasma leakage into the interstitial space may also occur. 1 •9 The development of angioedema secondary to ACEis is of particular interest in the case presented. 10• 1 1 In addition to inhibiting the conversion of angiotensin I to angiotensin II, the suppression of angiotensin-converting enzyme (ACE) results in reduced degradation of bradykinin and substance P. ACE is a dual-specificity dipeptidase that cleaves bradykinin and sub­ stance P into inactive peptides. Therefore, inhibition of this activity will result in increased levels of bradykinin and sub­ sequent tissue swelling.5 The association between ACEis and angioedema has been well described. Angioedema has also been

demonstrated to occur with the angiotensin II receptor block­ ers (ARBsf·8 albeit with a much attenuated incidence. There is a modest increase in risk for ARB-induced angioedema in patients who have previously experienced ACE!-induced angio­ edema, though most patients with ACEI-induced angioedema will not develop ARB-induced angioedema. 18 ACEI-induced angioedema has a predilection for the head and neck, rendering it a particular challenge in airway man­ agement.4 Epinephrine is the mainstay of acute treatment of allergy-induced angioedema. Adjunctive therapy includes anti­ histamines and corticosteroids. However, none of these agents are effective in HAE and of limited use in ACEI- and ARB­ induced angioedema.8'1 2 There is no role for FFP in ACEI- or ARB-induced angioedema. However, as mentioned above, FFP can be useful in the treatment of HAE due to the presence of C1 inhibitor.5 ACEI-induced angioedema is the most common cause of angioedema seen in US EDs, accounting for 1 7% to 38% of all angioedema cases. 1 3 In the omapatrilat versus enalapril (OCTAVE) antihypertensive trial, the investigators identi­ fied independent risk factors including increased incidence in African Americans, age greater than 65, history of drug rash, and history of seasonal allergies. 14 Other risk factors include female gender, history of smoking, increasing age, transplant recipients, and patients on immunosuppressive therapy.35 According to the literature, the incidence of ACEI-induced angioedema ranges from 0. 1 % to 1 % of all patients taking this class of drugs. 2 ,4·6· 14 As many as half of the patients affected are African American, 15 resulting in hospitalization rates ;::: 2 times higher in African American patients compared to non-African American patients in the United States. 1 6 Approximately 50% of all ACEI-induced angioedema cases occur within 1 week of starting the medica­ tion, with the remainder occurring anywhere from weeks to years after starting the drug.4 Discontinuation of the ACEI will resolve the angioedema, though the risk of recurrent angioedema attacks may persist for weeks. Patients who have experienced an angioedema attack and who continue with ACEI therapy are at significant risk of recurrence within 5 years.6 • What Is the Genera l Clin ical Course of

Angioedema?

The clinical course of angioedema is unpredictable and largely dependent on the underlying etiology. Patients with HAE usually report trauma, often minor (e.g. , dental visit) , followed by tissue swelling. They can present with swelling in variable anatomic areas such as the face, hands, arms, legs, GI tract, and genitalia. Abdominal symptomatology is a frequent cause of significant morbidity due to severe abdominal pain, intractable vomiting, and hypotension due to third-spacing. Inappropriate surgical investigations in unrecognized HAE have been reported.5 In one large series, 1 0% of the patients with HAE required definitive airway intervention because of upper airway edema. 17 The onset of IgE-mediated anaphylaxis is rapid and often life threatening if not treated appropriately.4 The clinical course of ACEI-induced angioedema is often subacute but extremely unpredictable, and life-threatening presentations requiring air­ way interventions do occur and are reported in up to 20% of

Ai rway M a n a g e m e nt in a Pati ent with A n g i oedema

these patients.4 According to the literature, between 0% and 2.2% of patients with angioedema are intubated. 15 This vari­ ability may reflect a spectrum of patients from those with acute severe disease to those with a less acute presentation who were intubated for concerns of disease progression. It is extremely difficult to predict which patients who present with a stable airway will progress to a requirement for airway intervention. Researchers from Boston retrospectively analyzed cases of ACEI-related angioedema and determined that increasing age and oral cavity/oropharyngeal involvement predicted the need for airway intervention. 15 Since the clinical course of angioedema, especially ACEI­ induced, is very unpredictable, and potentially life threatening, it is recommended that these patients be admitted to an environ­ ment where they can be closely monitored for at least 24 hours. • What I nvestigations Might One Employ

to Aid in the Diagnosis and Eval uate the Severity of the Disorder?

The severity of airway compromise on presentation will deter­ mine the extent of initial investigations of these patients, and thus the workup for HAE is typically undertaken after the acute episode has resolved. The unpredictable clinical course of this disorder demands that each of these patients be triaged as "emergencies" to a resuscitation area of the ED and attended to immediately by nursing and physician staff. Evaluation and management are carried out concurrently, as are appropriate in patients with life-threatening conditions. It is often obvious that the airway is in immediate jeopardy and this should trig­ ger calling for assistance and implementing a strategy to secure the airway. The decision for airway intervention will be based largely on the clinical signs of respiratory distress: accessory respiratory muscle use, difficulty swallowing saliva, muffied voice, stridor, dyspnea, agitation, and hypoxemia. Although early airway management is indicated for patients with rapidly progressive and severe upper and/or lower airway compromise, a trial of epinephrine is nearly always indicated particularly when the etiology is unknown. Airway management in these patients requires time to execute safely and epinephrine will work quickly in a significant proportion of cases. Upper airway presentations, such as stridor and dyspnea, indicate impend­ ing complete airway obstruction and mandate an aggressive approach and should alert the practitioners of the potential need for a surgical airway as part of a "double setup." If one has the luxury of time and possess the skill, severity may be assessed by flexible nasopharyngoscopy. 18 It is prudent to prepare for this procedure as though one were intending to perform an awake endoscopic-guided nasal intubation. This assumes that one has anesthetized the nasopharyngeal passage and prepared a nasotracheal tube through which the endoscope is passed in case the findings mandate intubation. It is pref­ erable that the scope used for this procedure be of sufficient length and stiffness to guide an endotracheal tube into the trachea. 18 Repeated nasopharyngoscopic evaluation at regular intervals may be indicated in the event immediate endotracheal intubation is not necessary. Any manipulation of the upper air­ way carries a risk of triggering a complete airway obstruction

and therefore nasopharyngoscopy requires immediate access to rescue equipment as part of a "double setup." A portable cross-table soft tissue x-ray of the airway is sel­ dom useful and it should be emphasized that this investiga­ tion must not delay care if the airway is compromised and must not mean that the patient leave the resuscitation area. These patients are always reluctant to lay flat for investigations, such as CT scanning and MRI evaluations. This hesitancy ought to alert the practitioner that the degree of airway obstruction is significant, rendering such studies contraindicated. Arterial blood gases and other laboratory investigations for the most part are not helpful in the management of these patients.

AI RWAY MANAGEMENT • How Does One Decide That I ntubation Is

Indicated?

This decision is most often made on clinical grounds and is based on the degree of upper airway obstruction present, and the pace at which it is anticipated to change. Diagnostic stud­ ies, with the possible exception of flexible endoscopic evalua­ tion of the airway, are not usually helpful in deciding when to intubate. As mentioned above, early airway intervention is the safest course of action, 19 particularly as the clinical course may be unpredictable. While epinephrine is usually administered for undifferen­ tiated presumed allergic etiologies, upper airway obstruction heralded by an altered voice, difficulty managing secretions, or stridor, should trigger a decision regarding urgent airway intervention. Other clinical signs motivating immediate inter­ vention include: air hunger (dyspnea) , confusion, agitation, or falling oxygen saturations. 1 7 • How Should t h e Ai rway b e Eva luated for

Difficulty?

These airways should always be considered "difficult" and managed according to the Difficult Airway Algorithm (see Chapter 2). Specifically, they £ail the MOANS analysis (see section "Difficult BMV: MOANS" in Chapter 1 ) for difficult bag­ mask-ventilation in that mask seal may be inadequate. But more importantly, adequate gas exchange may be prevented by edema­ tous upper airway tissue occluding the airway despite high pres­ sures generated by bag-mask devices. Ventilation may further be compromised at the alveolar level due to bronchoconstriction, alveolar edema, and retained secretions. Based on the airway evaluation using the mnemonic RODS (see section "Difficult Use of an EGD: RODS" in Chapter 1 ) , the use o f extraglottic devices (EGDs) will b e difficult. Insertion of the device may not be possible due to facial and oral edema and the larynx itself may be edematous to the point of obstruc­ tion. In addition, even if the EGD were to be inserted success­ fully, an effective seal may be difficult to obtain in an edematous hypopharynx. The failure of MOANS and RODS alone prohibits the use of paralytic agents, even if one felt that the LEMON and CRANE analyses (see sections "Difficult DL Intubation: LEMON" and

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"Difficult VL Intubation: CRANE" in Chapter 1 ) might per­ mit successful direct or indirect laryngoscopy and intubation. In other words, rapid sequence intubation (RSI) is usually imprudent. An assessment for cricothyrotomy is essential in these patients, as this procedure may emerge as the preferred and primary intervention for airway management and may be performed awake under local anesthesia. In summary, if laryn­ goscopy is unsuccessful or impossible in a patient who is very difficult to ventilate using a bag-mask, and alternative intubat­ ing techniques, and extraglottic rescue devices are unlikely to work, the surgical option has to be considered early in the plan­ ning and execution of airway management. • How Should This Patient's Airway be

Managed?

Some patients with angioedema have had prior episodes and may be able to provide some reassurance that this episode will resolve under close observation. However, such patients are few and the course of this disease is unpredictable. It is much more likely that the clinical course will be unpredictable and a more aggressive approach to airway management is therefore justified. Management is driven by the Difficult Airway Algorithm (see Chapter 2) . In the event that oxygen saturations are poor and cannot be improved, one is directed to the Failed Airway Algorithm and immediate cricothyrotomy. RSI is rarely an option in these patients. If there is time, the next step will depend on the practitioner's access to, and ability to use, a flexible bronchoscope (FB) . If an experienced practitioner is available, then intubation using FB ought to be performed with immediate cricothyrotomy as backup. The nasal route for the FB-guided intubation mentioned above is ordinarily much eas­ ier for those who infrequently perform endoscopic intubations. In the event one does not have, or cannot use, an FB then an "awake look" using either a direct or video-laryngoscope may help create a more informed decision to intubate awake or to move to awake surgical airway. It is often a difficult decision to use sedative hypnotic agents to facilitate airway evaluation and management in patients with upper airway obstruction in general, and angioedema in par­ ticular. Patients with upper airway obstruction maintain their airways by using every airway muscle at their disposal, and even small doses of these sedative agents may precipitate a complete upper airway obstruction. In small titrated doses, ketamine may be preferable in that it maintains muscle tone and respiratory drive. The disadvantages of "laryngeal sensitization," salivation, and confusion must be weighed against the positive aspects of using this drug. The use of topical local anesthetic agents in patients with upper airway obstruction is also not without risk. Several cases have been reported in the last decade of topicalization convert­ ing partial upper airway obstruction to complete obstruction (see section "Can Topical Lidocaine Anesthesia of the Upper Airway Cause Airway Obstruction?" in Chapter 3) . However, a practitioner may have no choice but to employ topicalization in an attempt to secure the airway. Blind (nonvisual) techniques such as blind nasal intubation and light-guided techniques are

relatively contraindicated due to the potential for airway distor­ tion and the risk of producing further trauma and bleeding.

S U M MARY The incidence of angioedema has increased dramatically over the past rwo decades with the introduction of ACE inhibitors and ARBs for the treatment of hypertension. The clinical course of any angioedema episode is unpredictable regardless of under­ lying etiology. For this reason, securing the airway early is a safer course than "watching and waiting." Commonly adminis­ tered medications including intravenous steroids, antihistamine and epinephrine, are of marginal value in bradykinin-mediated angioedema and utilization of these agents ought not delay air­ way intervention. Intubation over an FB may be the preferred technique; the nasal route being recommended for those who perform flexible intubation infrequently. Employing j udicious topical anesthesia may enable one to intubate using direct or indirect laryngoscopy; however, there must be an appreciation of the risk of converting a marginally patent airway into com­ plete airway obstruction and a "can't intubate, can't oxygen­ ate (CICO) situation. The Plan B option of surgical airway performed under local anesthesia with the patient awake must be considered as a backup, or in some cases, even a primary method of securing the airway.

As with all cases ofupper airway obstruction, one must appreci­ ate that while the patient may have "stable" vital signs, the airway is exceedingly "unstable"! REFERENCES 1 . Grigoriadou S, Longhurst HJ. Clinical Immunology Review Series: an approach to the patient with angio-oedema. Clin Exp fmmunol. 2009; 1 5 5 : 367-377. 2. Muelleman RL, Tran TP. Allergy, hypersensitivity and anaphylaxis. In: Marx JA, Hockberger R, Walls R, eds. Rosens Emergency Medicine: Concept and Clinical Practice. 5th ed. St. Louis, MO: Mosby; 2002: 1 6 1 9- 1 634. 3 . Zuraw BL, Bernstein JA, Lang DM, et al. A focused parameter update: hereditary angioedema, acquired C I inhibitor deficiency, and angiotensin­ converting enzyme inhibitor-associated angioedema. J Allergy Clin fmmunol. 20 1 3 ; 1 3 1 : 1 49 1 - 1 493. 4. Kaplan AP. Greaves MW. Angioedema. ]Am Acad Dermatol. 2005;53 :373388; quiz 89-92. 5 . Adkinson NF Jr, Bochner BS, Burks AW, et a!. Middletons Allergy: Principles and Practice. 8th ed. Philadelphia, PA: Elsevier Saunders; 20 1 4 . 6. Bheekie A , Obikeze K , Nicolson R . Angiotensin converting enzyme inhib­ itor induced angioedema in patients with primary hypertension (Protocol) . Cochrane Review. 2008. 7. Haymore BR, Yoon J, Mikita CP, Klote MM, DeZee KJ. Risk of angio­ edema with angiotensin receptor blockers in patients with prior angio­ edema associated with angiotensin-converting enzyme inhibitors: a meta-analysis. Ann Allergy Asthma Jmmunol. 2008; 1 0 1 :495-499. 8 . Simons FE, Gu X, Simons KJ. Epinephrine absorption in adults: intramuscular versus subcutaneous injection. J Allergy Clin Jmmunol. 200 1 ; I 0 8 : 8 7 1 -873. 9. Sampson HA, Munoz-Furlong A, Campbell RL, et al. Second sym­ posium on the definition and management of anaphylaxis: summary report-Second National Institute of Allergy and Infectious Disease/Food Allergy and Anaphylaxis Network symposium. J Allergy Clin fmmunol. 2006; 1 1 7:39 1 -397. 10. Chiu AG, Krowiak EJ, Deeb ZE. Angioedema associated with angiotensin II receptor antagonists: challenging our knowledge of angioedema and its etiology. Laryngoscope. 200 I ; I l l : 1 729- 1 73 1 . 1 1 . Gannon TH, Eby TL. Angioedema from angiotensin converting enzyme inhibitors: a cause of upper airway obstruction. Laryngoscope. 1 990; 1 00: 1 1 5 6- 1 1 60.

Ai rway M a n a g e m e nt i n a Pati ent with A n g i oedema 1 2 . Angioedema. Available at: http:/ /emedicine.medscape.com/article/ 1 3 5 604overview. Accessed February 1 6, 20 1 6 . 1 3 . Roberts JR, Wuerz RC. Clinical characteristics of angiotensin-converting enzyme inhibitor-induced angioedema. Ann Emerg Med. 1 9 9 1 ;20 : 5 5 5 - 5 5 8 . 14. Kostis J B , Kim HJ, Rusnak J, e t al. Incidence and characteristics of angio­ edema associated with enalapril. Arch Intern Med. 2005; 1 6 5 : 1 637- 1 642 . 1 5 . Zirkle M, Bhattacharyya N. Predictors of airway intervention in angioedema of the head and neck. Otolaryngol Head Neck Surg. 2000; 1 23:240-245. 1 6. Lin RY, Shah SN. Increasing hospitalizations due to angioedema in the United States. Ann Allergy Asthma Immunol. 2008; 1 0 1 : 1 8 5 - 1 92. 1 7. Bernstein S, Buckley PJ, Pollack CV, Walls R. Intubation strategies in patients with angioedema or intraoral obstruction: a multicenter study. Acad Emerg Med. 1 999;6:5 1 8 . 1 8 . Bentsianov BL, Parhiscar A , Azer M, Har-El G. Th e role o f fi.beroptic naso­ pharyngoscopy in the management of the acute airway in angioneurotic edema. Laryngoscope. 2000; 1 1 0:201 6-20 1 9 . 1 9. Thompson T, Frable MA. Drug-induced, life-threatening angioedema revisited. Laryngoscope. 1 993; 1 03 : 1 0- 1 2.

SELF-EVALUATION QU ESTIO N S 26. 1 . ACE-inhibitor-induced angioedema patients A. usually respond to subcutaneous and aerosolized epinephrine B. have an unpredictable clinical course with respect to the airway

C. can usually be safely observed as long as they do not have stridor D. usually respond to high-dose intravenous steroids E. can be managed with fresh frozen plasma 26.2. All of the strategies for definitive airway management are acceptable in patients with angioedema EXCEPT A. awake intubation using a flexible bronchoscope B. awake intubation under direct laryngoscopy C. rapid sequence intubation D. cricothyrotomy E. tracheotomy 26.3. Which of the following symptoms would suggest a marginally patent airway that requires definitive airway management? A. stridor B. muffled voice C. oxygen desaturation D. difficulty managing secretions E. use of accessory muscles

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Airway Manage ment for Penetratin g Facia l Trauma David A . Caro and Aaron E. Bair

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CASE PRESENTATION A 70-year-old depressed man presents after attempted suicide by shooting himself with a handgun held under his jaw. He is seated upright and leaning forward when paramedics arrived on the scene and refuses to lie supine due to facial bleeding. He is kept in position so as to optimize airway patency and expedi­ tiously transported to the nearest emergency department (ED) . The patient presents to the ED in tripod position with obvi­ ous bleeding from his mouth. His anterior mandible is missing, and he is holding a non-rebreather oxygen mask in front of his face. His oxygen saturation is 95% and has been stable during transport. Vital signs include a pulse of 85 beats per minute, a blood pressure of 1 75/90 mm Hg, a respiratory rate of 22 breaths per minute, and a temperature of 3rC. Upon initial examination (Figure 27- 1) , he had ongoing oral hemorrhage and completely missing anterior mandible. The patient is awake and has a Glasgow Coma Scale (GCS) of 1 5 . In light of his injuries, he was kept upright on the gurney in anticipation of tracheal intubation (for airway protection) .

F I G U R E 27- 1 . The picture s h ows that patient a rrived at the emerg e n cy d e p a rtment sitt i n g o n a stretc her with a non­ rebreather oxygen mask.

PATI ENT ASSESSMENT • What Are the Airway Eva luation

Considerations in This Patient?

This patient presents with multiple clinical issues that may influence his airway management. The missing anterior man­ dible is a dramatic presentation, but standard trauma manage­ ment principles apply. 1' 2 His airway does require management, as indicated for airway protection and anticipated clinical course. However, this is not a "crash" intubation situation (because his oxygen saturation is > 90% and stable) . Therefore, a rapid evaluation of the airway for anticipated difficulty is pos­ sible.3 If this was a "crash" scenario (e.g. , vital signs become unstable or patient becomes hypoxic) , an awake cricothyrot­ omy might be the most appropriate initial approach. 1•3

Ai rway M a n a g e m e n t for Pe netrati n g Fa c i a l Tra u m a

The presence of oro-facial disruption will likely hinder bag­ mask-ventilation (BMV) due to a poor mask seal. Similarly, with the associated hemorrhage, soft tissue edema, and the presence of foreign bodies (teeth, clots, etc.), the use of an extraglottic device (EGD) may be difficult. Laryngoscopy will likely be complicated by the presence of blood, tissue edema, and possible airway disruption. However, the absence of man­ dibular resistance might actually make visualization easier. While it is always wise to consider cervical spine inj ury in the setting of head injury, this case is special as the patient is neu­ rologically intact and this places him in a low-risk category for spine inj ury. To date, there have been no cases reported of iso­ lated penetrating injury to the face that have resulted in an unstable cervical spine fracture in an awake, alert, neurologically intact patient.4'5 Maintenance of strict cervical spine precau­ tions in this instance, such as lying the patient supine or placing the patient in a cervical collar could result in aspiration and obstruction of the airway. 2 In this instance, maintaining the patient in a position of relative comfort in an upright, sitting position allows the patient to keep their airway open, manage bleeding, and provides the clinician an opportunity for further assessment in planning their approach. This airway is classified as "difficult," specifically for potential challenges that may be encountered during laryngoscopy and mask-ventilation. • How Does Ai rway Assessment Proceed in

the Setting of Disrupted Anatomy?

Significant penetrating facial injuries can present significant dif­ ficulties isolating landmarks. A "look, listen, feel" approach to airway evaluation is wise. Critical structures to identifY include the tongue, the hypopharynx, and the larynx. The tongue fre­ quently remains present in penetrating facial injuries, but can also be disrupted by the trauma. Key to airway evaluation is identification of the glottis at the base of the tongue. Hence, sequential visualization of the anatomy from the base of the tongue can direct the airway practitioner to the glottis. Airway sounds, such as gurgling, pose a potential aspiration threat usu­ ally from bleeding. More concerning is stridor or the inabil­ ity to phonate which may indicate impending compromise. Palpation of airway anatomy might allow for identification of otherwise unrecognizable structures, such as the grossly abnor­ mal tongue, mandible, etc., and will also allow the practitioner to identifY the position of the larynx in the neck to localize the target for cricothyrotomy if it is necessary. • How Is Airway Hemorrhage Managed in

This Circumstance?

Patient positioning is paramount. 2 Severe hemorrhage requires consideration of sitting the patient upright or rolling the patient into a lateral decubitus position to allow gravity to assist mov­ ing blood out of the airway. It merits emphasizing that gravity can also work against the airway practitioner if the patient is forced to lie flat when hemorrhage is severe. Adequate suction is a necessity; plan to have at least two devices available to allow for adequate suction. Direct pressure with 4 X 4 gauze might be of use if the bleeding site is within reach. Topical vasocon­ stricting medications will most unlikely be successful. Injected

lidocaine with epinephrine i s a n occasional consideration once airway stability is confirmed. • How Often Is a Penetrating Facial I nj u ry

Associated with Cervical Spine I njury?

The incidence of associated cervical spine fracture with severe blunt facial trauma ranges from 1 % to 6% of patients. 2·6-9 While incidence of cervical spine fracture with penetrating facial wounds can be relatively high (8 . 1 %-23%) ,4•5 there are no case reports of penetrating facial/head injury in a neurologically intact patient that has resulted in an unstable cervical spine fracture. Immediately forcing a patient into a cervical collar or supine positioning, however, might result in catastrophe. Caution and common sense should guide emergency medical service (EMS) personnel and the emergency airway practitioner. If no con­ comitant trauma issues exist (e.g. , a fall from a height after the penetrating wound) , allowing the patient to stay in a position of comfort can be lifesaving. • What Other Concerns Do You Have for

Th is Patient?

Denitrogenation will be difficult, as any mask device will not provide a good seal and will also serve to pool blood and fur­ ther compromise the airway. 1 Alternatives to non-rebreather masks or bag-mask devices include blow-by oxygen with a non­ rebreather mask held in front of the airway, and nasal oxygen by a high-flow nasal cannula. If nostrils are intact, both might be employed simultaneously. If induction of anesthesia is deemed necessary, a cerebra­ protective sedative (e.g. , propofol, benzodiazepines, or barbi­ turates) is warranted, but care must be taken not to induce or exacerbate hypotension. Etomidate may be attractive because of its associated "hemodynamic stability," and is neutral in its effects on ICP. 10-14 Based on patient assessment an awake approach would be the preferred method of managing this patient's airway. Ketamine may allow "facilitated cooperation," provide analgesia, and allow further assessment of the patient's . even auway. 15-17 Recent ev1' dence supports th e use o f ketamme in the instance of head trauma as the concern for ICP rise with the use of ketamine is offset by the increase in cerebral , o f agents IS , o f parncu . . 1ar per fius1on pressure. 18 ' 19 1h e ch mce importance when caring for patients with a diminished cardiac reserve, such as those with severe cardiac disease, those who are critically ill, or patients who are elderly. These patients are more prone to a hypotensive response than are healthier patients with similar injuries. As this is not a "crash" intubation situation, an evaluation of the airway for anticipated difficulty is possible. ·

• What I nvestigations Are Warranted for

Th is Patient Before Proceeding to Airway Management?

A priority in managing patients with trauma is adequate oxy­ gen delivery. Airway intervention usually takes precedence over any further investigation or intervention. Some may argue that plain film imaging of the face and neck may give additional information related to the destructive path of the projectile,

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which may help plan the approach to the airway. However the value of such imaging is questionable and is insufficient in its ability to exclude a potential spinal injury and should not delay airway management. 1'2 Concurrent resuscitation and evaluation is key to trauma care, meaning that relevant investigations are underway at the same time airway intervention is undertaken and do not delay management.

AI RWAY MANAGEMENT • What Are the Ai rway Ma nagement

Considerations One Needs to be Aware of?

The initial plan should anticipate difficult laryngoscopy, dif­ ficult EGD placement, and difficult BMV The practitioner should also consider how the patient ought to be positioned for laryngoscopy, as the volume of bleeding and the mechanical stability of the airway might preclude supine positioning. 2 1he preferred method in such a patient would be awake with the patient seated upright.3 An RSI would not be considered as a primary approach, in part as it would require the patient to lie flat. It must be recognized that failure of intubation and BMV is a significant possibility in this patient.3 In such a circum­ stance, the efficacy of many of the common alternative devices would also be compromised. The EGDs such as the intubating laryngeal mask, the King LT, and Combitube'M airway require intact hypopharyngeal structures to seat correctly, and so might be difficult to place. Vision with video-laryngoscopy, such as the GlideScope", C-MAC", or flexible bronchoscope may be obscured in the presence of blood.1 '20 Regardless of approach, preparation for a surgical airway as part of a double setup requires that cricothyrotomy equipment be readily available. • What Procedure Should be Used to I ntubate

the Trachea of Th is Patient?

Timing and positioning in anticipation of airway management is an important consideration. The patient is able to maintain his airway as he is sitting up. This positioning allows blood, bone fragments, and macerated tissue to be displaced away from the airway. In contrast, immediately placing the patient supine strictly for concern of cervical spine injury or reflexively resorting to typical airway management positioning, could place his already tenuous airway at undue risk. 2 Given the soft tissue disruption and continued hemorrhage, one would anticipate that he would quickly obstruct his airway in a supine position. Denitrogenation should take place in the patient's original position of comfort. Help should be summoned from other experienced airway prac­ titioners and surgical colleagues to be immediately available to assist in managing this patient.3 Once all preparations for the dif­ ficult airway have been made, the practitioner needs to determine what plan to employ for airway management. Penetrating facial trauma has a potential to cause a difficulty directly, from disruption of the upper airway or secondarily cause challenges related to problems maintaining airway patency from the disrupted soft tissues, or protecting the airway from significant bleeding. Plan A in this case would include an awake look/intubation, which is best achieved through the nose if the patient's anatomy allows this. A nasopharyngoscope may allow

visualization of the airway and bypass much of the pathology, but as discussed above, it may be challenging in the presence of blood. Better option is the use of a flexible bronchoscope after place­ ment of an endotracheal tube (ETT) through a topicalized nose (advance the ETT to 1 4 to 1 6 em for an average size adult) . This allows protection of the scope from blood and should provide a good view of the glottis as the bronchoscope exits the supra­ glottically positioned ETT. Additional topical anesthetic can be delivered through the functioning channel of the bronchoscope before tracheal intubation with rhe patient seated upright facili­ tated by procedural sedation doses of an intravenous sedative agent. 2 An awake oral approach may also be considered but will be challenging as displacement pressure on disrupted and bloody soft tissue with inadequate topicalization may be very difficult. The practitioner could employ a reversed-blade laryngos­ copy (also known as the "Tomahawk" technique) with either the direct laryngoscope or the video-laryngoscope (if hem­ orrhage is not excessively severe and the camera will not be covered by blood) . 2 1 Ketamine sedation and analgesia should be initiated prior to any laryngoscopy attempt. The technique requires the airway practitioner to hold the laryngoscope upside down in the right hand while standing and facing the patient. The blade is then used to "walk" back along the top of the tongue while applying gentle pressure down-and-away from the airway to open the mouth for visualization. An assistant is required to hold the patient's head from coming forward once the attempt commences. In severe cases where the maneuver is not immediately successful in obtaining a view of the glottis and any portion of the tongue remains intact, a zero-silk on a curved needle can be placed through the tongue and the airway pulled anteriorly under the blade to allow glottis visualization. Alternatively, a pair of Babcock forceps can be used to grasp the tongue and pull the airway anteriorly. Once airway struc­ tures are visualized, the airway can be immediately intubated. Further sedation and subsequent paralysis might be required after tracheal intubation to assist in securing the ETT and ini­ tiating mechanical ventilation. Another consideration would be to lie the patient in a lateral decubitus position (see Figures 27-2 and 27-3) with an attempt with continued sedation and traditional oral laryngoscopy; this

F I G U R E 27-2. Di rect l a ryngoscopy in latera l decubitus position i n a patient with penetrat i n g fac i a l tra u m a .

Ai rway M a n a g e m e n t for Pe netrati n g Fa c i a l Tra u m a

POST-I NTU BATION MANAG EM E NT • What Other Issues Should be Considered

Following Tracheal I ntubation?

F I G U R E 27-3. La ryngosco pic i ntu bation i n l atera l dec u b itus position i n a patient with penetrati n g fac i a l tra u m a .

may provide a different view o f the airway that might allow successful intubation. A sequence of predetermined steps should be employed if failure with laryngoscopy or oxygenation occurs, including the timing to employ Plan B which would, in this case, be a surgical airway. The patient's neck should be prepped prior to the initial awake look approach, and cricothy­ rotomy equipment should be opened and ready for use, in the event that the preceding steps fail to secure the airway. Finally, an awake tracheotomy or cricothyrotomy could be considered as a primary approach if an oral and/or nasal route is predicted to be or encountered as difficult. Preparation begins by assembling standard intubating equipment, alternative airway devices, and a surgical airway kit. Denitrogenation and oxygenation with high-flow nasal oxygen in combination with a non-rebreather mask (which might need to be held slightly away from the face to avoid pool­ ing of blood if there is significant bleeding) should be initiated well in advance of induction. 22 Continuous nasal oxygenation during laryngoscopy attempts might provide oxygenation sup­ port during this vulnerable period of time. 23 ·24 Uncontrolled epistaxis may impede this process, can lead to aspiration, and may require immediate packing or cauterization. Having two functioning rigid suctions is essential. As discussed, an awake approach can be performed with ket­ amine as a sedative agent. Ketamine is a potent analgesic, has favorable hemodynamic properties, and most importantly should allow the patient to maintain protective their airway reflexes while facilitating laryngoscopy and intubation. 2 5· 26 If forced to act, a rapid sequence intubation (RSI) might be considered as part of a double setup with immediate concurrent initiation of a cricothyrotomy. 27 While Sellick's maneuver (cricoid pressure) has fallen out of favor, as no literature exists to support benefit and mounting evidence of it causing difficulty with intubation, mask-ventilation, and EGD use, 2 8-31 many airway management organizations, including the Canadian Airway Focus Group,32 continue to recommend the use of cricoid pressure during RSI in high-risk patients. However, if difficulty is encountered with face-mask-ventilation, use of EGD, or tracheal intubation, cri­ coid pressure should be progressively or completely released (see section "Cricoid Pressure" in Chapter 5).32

Capnography, if available, or capnometry should be used to confirm ETT placement. Securing the ETT is critical and chal­ lenging in this case. Traditional tracheal taping may not be suc­ cessful due to excessive bleeding or secretions. The practitioner might need to use a dedicated ETT holder that screws onto the ETT and is held in place by Velcro straps, or for short-term stabilization a length of IV tubing can be used to wrap around the neck and then encircle the ETT, allowing the airway prac­ titioner to wrap the ends around the ETT and tie off in a knot to keep the tube in place. Importantly, the patient should be adequately sedated to prevent accidental extubation, and pain control should be addressed. A cervical collar can then be placed to limit neck movement and subsequent ETT displacement.

S U M MARY A penetrating maxillofacial injury can significantly impair both the ability to bag-mask-ventilate a patient and perform laryn­ goscopy. Careful consideration must be given to approach this difficult airway. The lesson from this patient is to have backup plans ready in the event that the trachea cannot be intubated orally.

REFERENCES 1. Barak M, Bahouth H, Leiser Y, Abu EI-Naaj I. Airway management of the patient with maxillofacial trauma: review of the literature and suggested clinical approach. BioMed Res Int. 20 1 5 ;20 1 5 :724032. 2. Perry M, Morris C. Advanced trauma life support (ATLS) and facial trauma: can one size fit all? Part 2: ATLS, maxillofacial injuries and airway management dilemmas. lnt J Oral Maxillofoc Surg. 2008;37(4) :309-320. 3. Walls RM . Identification of the difficult and failed airway. In: Walls RM , ed. Manual of Emergency Airway Management. 4th ed. Philadelphia, PA: Lippincott Williams and Wilkins. 20 1 2: 8-22. 4. Demetriades D, Chahwan S, Gomez H , Falabella A, Velmahos G, Yamashita D. Initial evaluation and management of gunshot wounds to the face. ] Trauma. 1 998;45 ( 1 ) :39-4 1 . 5 . Medzon R, Rothenhaus T, Bono CM, Grindlinger G , Rathlev NK. Stability of cervical spine fractures after gunshot wounds to the head and neck. Spine. 2005 ;30(20) :2274-2279. 6. Ardekian L, Gaspar R, Peled M, Manor R, Laufer D. Incidence and rype of cervical spine injuries associated with mandibular fractures. ] Craniomaxillofoc Trauma. 1 997;3 (2) : 1 8-2 1 . 7 . Bayles SW, Abramson PJ, McMahon SJ, Reichman OS. Mandibular frac­ ture and associated cervical spine fracture, a rare and predictable inj ury. Protocol for cervical spine evaluation and review of 1 382 cases. Arch Otolaryngol Head Neck. 1 997; 1 23 ( 1 2) : 1 304- 1 307. 8. Beirne JC, Butler PE, Brady FA. Cervical spine injuries in patients with facial fractures: a 1 -year prospective study. lnt J Oral Maxillofoc Surg. 1 995;24 ( 1 pt 1 ) : 26-29. 9. Hang RH, Wible RT, Likavec MJ, Conforti PJ. Cervical spine fractures and maxillofacial trauma. } Oral Maxillofoc Surg. 1 9 9 1 ;49 (7) : 725-729. 10. Guldner G, Schultz J, Sexton P, Fortner C, Richmond M. Etomidate for rapid-sequence intubation in young children: hemodynamic effects and adverse events. Acad Emerg Med. 2003; 1 0 (2) : 1 34- 1 39. 1 1 . Gauss A, Heinrich H, Wilder-Smith OH. Echocardiographic assessment of the haemodynamic effects of propofol: a comparison with etomidate and thiopentone. Anaesthesia. 1 9 9 1 ;46 (2) :99-1 0 5 . 1 2 . Jellish WS, Riche H, Salord F, Ravussin P, Tempelhoff R . Etomidate and thiopental-based anesthetic induction: comparisons between different titrated levels of electrophysiologic cortical depression and response to laryngoscopy. } Clin Anesth. 1 997;9 ( 1 ) :36-4 1 .

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Ai rway M a n a g e m e n t in the E m e rg e n cy Room 1 3 . Bramwell KJ, Haizlip J, Pribble C, VanDerHeyden TC, Witte M. The effect of etomidate on intracranial pressure and systemic blood pressure in pediatric patients with severe traumatic brain injury. Pediatr Emerg Care. 2006;22(2) :90-93. 14. Modica PA, Tempelhoff R. Intracranial pressure during induction of anaes­ thesia and tracheal intubation with etomidate-induced EEG burst suppres­ sion. Can } Anaesth. 1 992;39 (3) :236-24 1 . 1 5 . Krauss B , Green SM. Procedural sedation and analgesia in children. Lancet. 2006;367(95 12) : 766-780. 1 6. Krauss BS, Krauss BA, Green SM. Procedural sedation and analgesia in children. N Eng!} Med. 20 1 4;370 ( 1 5) :e23. 1 7. Green SM, Rothrock SG, Lynch EL, et a!. Intramuscular ketamine for pediatric sedation in the emergency department: safety profile in 1 ,022 cases. Ann Emerg Med. 1 998;3 1 (6) :688-697. 1 8 . Hughes S. Towards evidence based emergency medicine: best BETs from the Manchester Royal Infirmary. BET 3: is ketamine a viable induction agent for the trauma patient with potential brain inj ury. Emerg Med }. 20 1 1 ;28 ( 1 2) : 1 076- 1 077. 1 9. Chang LC, Raty SR, Ortiz J, Bailard NS, Mathew SJ . The emerging use of ketamine for anesthesia and sedation in traumatic brain inj uries. CNS Neurosci 7her. 20 1 3 ; 1 9 (6):390-39 5 . 2 0 . Brar MS. Airway management in a bleeding adult following tonsillectomy: a case report. AANA }. 2009;77(6) :428-430. 2 1 . Silverton NA, Youngquist ST, Mallin MP, et a!. GlideScope versus flexible fiber optic for awake upright laryngoscopy. Ann Emerg Med. 20 1 2; 5 9 (3): 1 5 9 - 1 64. 22. Mort TC. Preoxygenation in critically ill patients requiring emergency tra­ cheal intubation. Crit Care Med. 2005;33 ( 1 1 ) :2672-2675 . 2 3 . Engstrom J, Hedenstierna G, Larsson A . Pharyngeal oxygen administra­ tion increases the time to serious desaturation at intubation in acute lung injury: an experimental study. Crit Care. 20 1 0 ; 1 4 (3 ) : R93. 24. Taha SK, Siddik-Sayyid SM, EI-Khatib MF, Dagher CM, Hakki M, Baraka AS. Nasopharyngeal oxygen insuffiation following pre-oxygenation using the four deep breath technique. Anaesthesia. 2006; 6 1 (5) :427-430. 25. Sibley A, Mackenzie M, Bawden ], Anstett D, Villa-Roe! C, Rowe BH. A prospective review of the use of ketamine to facilitate endotracheal intubation in the helicopter emergency medical services (HEMS) setting. Emerg Med}. 20 1 1 ;28(6) : 52 1 -525. 26. Begec Z, Demirbilek S, Onal D, Erdil F, Ilksen Toprak H, Ozcan Ersoy M. Ketamine or alfentanil administration prior to propofol anaesthesia: the effects on ProSeal laryngeal mask airway insertion conditions and haemodynamic changes in children. Anaesthesia. 2009;64(3):282-286. doi: 1 0. 1 1 1 1 /j . 1 365-2044. 2008.05782.x. 27. Patanwala AE, Stahle SA, Sakles JC, Erstad BL. Comparison of succinyl­ choline and rocuronium for first-attempt intubation success in the emer­ gency department. Acad Emerg Med. 2 0 1 1 ; 1 8 ( 1 ) : 1 0- 1 4. 28. Levitan RM . Cricoid pressure impedes first pass intubation success and contributes to difficult laryngoscopy in emergency airway. 2006 Annual Meeting of the Society for Academic Emergency Medicine (SAEM 2006) . San Francisco, CA, 2006. 29. Palmer JH, Ball DR. The effect of cricoid pressure on the cricoid cartilage and vocal cords: an endoscopic study in anaesthetised patients. Anaesthesia. 2000; 5 5 (3):263-268. 30. Harris T, Ellis DY, Foster L, Lockey D. Cricoid pressure and laryn­ geal manipulation in 402 pre-hospital emergency anaesthetics: essential

safety measure or a hindrance to rapid safe intubation? Resuscitation. 20 1 0;8 1 (7) : 8 1 0-8 1 6 . 3 1 . Corda D M , Riutort KT, Leone AJ, Qureshi MK, Heckman M G , Brull SJ . Effect of j aw thrust and cricoid pressure maneuvers on glottic visualization during GlideScope video laryngoscopy. j Anesth. 20 1 2;26 (3) :362-368. 32. Law JA, Broemling N, Cooper RM , et a!. The difficult airway with recom­ mendations for management: part 2. The anticipated difficult airway. Can ]Anesth. 2 0 1 3;60(1 1 ) : 1 1 1 9- 1 1 3 8.

SELF - EVALUATION QU ESTIONS 27. 1 . The patient above presents i n tripod position t o main­ tain adequate breathing. Blow-by oxygen is provided by mask. Appropriate strategies to initially secure the airway would NOT include A. keep the patient seated upright during awake look B. attempt blind nasal intubation C. assemble equipment for cricothyrotomy D. call for immediate assistance from a surgical colleague E. use of personal protective equipment 27.2. In the above scenario, when would a primary cricothy­ rotomy be appropriate? A. on initial presentation B. once the surgical colleague arrives C. after the initial attempt at awake look fails while oxy­ gen saturation is 98% D . persistent oxygen desaturation E. with nasal hemorrhage that prevents blind nasal intubation 27.3. The incidence of associated unstable cervical spine frac­ ture in a neurologically intact patient with penetrating facial trauma A. is negligible B. is not a concern provided a cervical collar that provides rigid immobilization is used C. ranges from 1 o/o to 2 . 6% of patients D. in some studies approaches 20% E. has never been studied

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Airway Manage ment in a Patient with a Dee p Nec k Infection Kirk J. MacQuarrie

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I NTRO DUCTION .

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experienced practitioner. Fortunately for acute care providers, these present relatively infrequent. A typical ENT referral cen­ ter may see only one to three adult cases per year requiring airway management. As in this case, the deep neck infection is often odontogenic. Intravenous drug abuse is another impor­ tant cause. Most patients are aged 40 to 60 and there is a pre­ dominance of males. 1 Many cases of deep neck infections do not have an identifiable etiology. 2 Diabetes mellitus may also be a risk factor and its presence tends to be associated with more aggressive infection. 3 ,4 • Do All Deep Neck I nfections Require

Ai rway I ntervention?

CASE PRESENTATION A 32-year-old man (Figure 28- 1) presented to the emergency department (ED) with dysphagia, dysphonia, and dyspnea. Further inquiry revealed a 1 -week history of right-sided jaw pain. This was initially treated with oral antibiotics and anal­ gesics by his family doctor while awaiting an appointment with his dentist. He saw his dentist the preceding day and had an abscessed molar tooth extracted from his right mandible. Unfortunately, his pain continued and he developed swelling and fever, prompting him to present to the ED. His past medi­ cal history was unremarkable, and aside from his remaining prescription of the penicillin and hydromorphone, he was on no medications. He had no known allergies.

Most patients with deep neck infections can be managed con­ servatively without surgical intervention and do not require intervention to maintain the patient's airway.5•6 A conservative

I NTRODUCTION • Discuss the Incidence and Etiology of Deep

Neck I nfections in Ad u lts

The management of the patient whose airway is compromised due to a deep neck infection is a challenge for even the most

F I G U R E 28- 1 . Th i s 32-year- ol d m a n p resented with dys p h a g i a , dys p h o n ia, a n d d y s p n e a . There was ma rked swel l i n g o f the r i g h t side o f the n e c k . Due t o ma rked d i sco mfort, he was u na b l e t o pro­ trude h i s ton g u e for proper p h a ry n g ea l eva l uation.

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approach with antibiotics and depending on the etiology, ste­ roids may be all that is required. Even epiglottitis in the adult population only rarely will require airway manipulation in the form of intubation or tracheotomy. The most common deep space neck infections seen in the ED are tonsillar or periton­ sillar and usually represent a cellulitis that can be successfully treated with antibiotics alone. Small, localized abscesses, such as peritonsillar abscesses, are often treated with needle aspira­ tion or incision and drainage, followed by antibiotics. Although patients may present with altered phonation and upper airway dyspnea, airway compromise is very rare. Postoperative neck infections may present acutely and can be associated with an airway distorting neck hematoma. The diagnosis is usually obvious clinically; however, CT allows further delineation of the pathology. Interestingly, there has been a case report of an over-inflated King Laryngeal Tube mimicking Ludwig's angina that actually resulted in a tracheotomy.7 With the increasing popularity of extra-glottic devices, airway practitioners should be aware of this potential problem. There has also been a case report of a warfarin-induced sub­ lingual hematoma mimicking Ludwig's angina. 8 Fortunately in this case there was no airway compromise and the patient was successfully managed by reversing the coagulopathy. • What Is Ludwig's Angina?

This potentially life-threatening infection of the floor of the mouth was first described in 1 836 by Wilhelm Frederick von Ludwig. The condition has also been called morbus strangula­ torius, angina maligna, and garotillo (Spanish for "hangman's loop") . These older terms reflect the high mortality, typically by total airway obstruction, in the days before antibiotics. Ludwig's angina is defined as severe bilateral cellulitis and edema of the submandibular and sublingual spaces. "Woody" swelling of the submandibular area in a febrile patient with a history of jaw pain is the classic presentation. The infection may cause swelling of the tongue and epiglottis that will then impair the ability to swallow and clear secretions. Total airway obstruc­ tion may result from progressive swelling or from laryngospasm secondary to aspiration of pus secretions, or both.9 While most cases of deep neck infections can be managed conservatively with antibiotics alone, true cases of Ludwig's angina typically require more aggressive intervention, including surgical drain­ age and definitive airway management. Treatment of Ludwig's angina is three-pronged and involves: airway management, antibiotic therapy, and surgical drainage.

ASSESSMENT OF TH E PATIENT • Why Might Airway Management be Difficult

in Patients with Ludwig's Angina?

Patients with Ludwig's angina or a retropharyngeal abscess fre­ quently have the potential to create difficulty with all aspects of airway management: bag-mask-ventilation (BMV) , ventilation using extraglottic devices (e.g. , LMA) , laryngoscopy and tra­ cheal intubation, and performing a surgical airway.

The oropharyngeal and sublingual swelling leads to displace­ ment of the tongue. With progression, deep space infection may track and involve periglottic region. Stridor represents a late pre­ sentation with impeding airway collapse. BMV if required would be a challenge and necessitate high airway pressures to produce adequate gas flow. High-flow nasal oxygenation would be better tolerated and may bypass the obstructive oropharyngeal pathol­ ogy. These patients are often dependent on position for airway patency and so maintaining an upright posture and avoiding seda­ tion if possible is prudent. It may prove difficult or impossible to open the airway of the sedated or unconscious patient due to loss of muscle tone and the resultant further narrowing of the airway. Copious secretions may increase the risk of laryngospasm and tongue swelling may preclude use of an oral airway. A nasal airway is an option but bleeding could possibly trigger laryngospasm. Upward displacement of the tongue by the infection can make insertion of any of the extraglottic rescue devices difficult or impossible. Although Brimacombe et al. 1 0 reported the successful use of a small Laryngeal Mask Airway (#2) as a rescue device for a hypoxic adult patient with quinsy, extraglottic "rescue devices" for failed BMV may be ineffective due to glottic edema. Secretions and edema, particularly tongue swelling, will make direct laryngoscopy more difficult regardless of the type of blade chosen. Nuchal rigidity, trismus, or both may be improved with sedation or muscle relaxants but there is no guarantee that these agents will be effective. Blind intubation techniques, such as the Intubating Laryngeal Mask Airway and lighted stylets (such as the Trachlight'M, which sadly is no longer produced) would not generally be considered for first-line use in these patients as these techniques run the risk of disrupting infected tissue and potentially soiling the airway. Furthermore, these nonvisual intubating techniques could result in laryngospasm during the intubation attempt. Typically these patients have heavy secre­ tions and occasionally some bleeding, limiting the use of indi­ rect visual techniques such as the flexible and rigid fiberscopes and video-laryngoscopes. In true cases of Ludwig's angina, oral intubation with any instrument is frequently not an option due to limited oral access. Most experts would advocate either a nasal intubation or a surgical approach. Unfortunately, performing a surgical airway in this patient population is difficult. The anatomy is often distorted due to swelling and hyperemic tissues may increase the likelihood of bleeding. In some patients, the abscess may involve the area surrounding the trachea. Supine positioning of the patient to perform a surgical airway may worsen dyspnea and reduce the patient's cooperation. To add to the difficulty of airway management in these patients, all possible options of ventilation and oxygenation are fraught with danger. The ultimate decision will be made based on the urgency of the clinical circumstance, the available resources, the careful setting of priorities, and the skill and expe­ rience of the airway team (anesthesia practitioner and surgeon) . • Discuss the Role of Diagnostic I maging in

Assessing These Patients

A lateral neck x-ray is often performed in these situations and may demonstrate submandibular and retropharyngeal edema but seldom provides enough information to direct management.

Ai rway M a n a g e m e n t in a Patient with a Deep Neck I nfection

The advent of the CT scan has revolutionized the ability to accurately assess the swollen, inflamed neck. In addition to determining the severity of the infection involving different tis­ sue planes and neck spaces, the resolution of the CT scan can help to differentiate berween a cellulitis and an abscess. The CT scan can also determine the presence or absence of j ugular vein thrombosis. Unfortunately, in the presence of a rapidly deteriorating airway, it will usually be necessary to proceed with emergency airway management before a CT examination of the neck becomes available. Even in patients with "stable" airways, a CT scan may not be possible prior to definitive airway man­ agement because the patient may be unable to lie flat. In these cases, the CT scan is done to better determine the extent of the infection only after securing an airway. As technology and skills improve, some authors have sug­ gested that bedside ultrasonography play more of a role in man­ agement of these patients . 1 1 This could potentially alleviate the problems of positioning associated with CT, and provide faster useful information. • Discuss the Technique of

Nasopharyngoscopy and Its Role in the Management of Patients with Deep Neck I nfections

Nasopharyngoscopy is a safe and simple technique which should become familiar to anesthesia practitioners, otolaryn­ gologists, and emergency specialists. Following the application of topical vasoconstrictor and topical anesthetic (4% lidocaine) , the flexible nasopharyngoscope is passed into the nasopharynx. The glottis should not be anesthetized as this could trigger laryngospasm. With the flexible nasopharyngoscope, the glottis can be viewed from above without the risk of provoking laryn­ gospasm. The technique is usually first done in the ED as part of the initial evaluation, and repeated at the bedside or in the operating room as required to provide an ongoing evaluation of the airway. Serial nasopharyngoscopic assessments become particularly important if conservative airway management is decided upon. • How Was Th is Patient Assessed?

On examination, he appeared anxious and in severe discomfort. He was febrile with a temperature of 38 .7"C. His respiratory rate was 26 breaths per minute. His heart rate was 1 04 beats per minute and his blood pressure was 1 32/76 mm Hg. His oxygen saturation was 9 1 o/o on a non-rebreather face mask. He had a marked decrease in the range of motion of his neck. Significant swelling and erythema was observed extending from the right submandibular region, crossing the midline, and down the neck to include his left upper chest. A lateral x-ray of the neck was remarkable for submandibu­ lar and retropharyngeal swelling along with a diminished air­ way caliber (Figure 28-2) . Although potentially helpful, a CT scan was not done as it was felt that the patient could not toler­ ate lying flat, even for a short period of time. Nasopharyngoscopy was performed in the ED by the ENT resident and revealed right lateral pharyngeal swelling and pos­ terior displacement of the epiglottis obscuring the vocal cords.

F I G U R E 2 8 - 2 . A l t h o u g h t h i s l atera l x-ray v i e w o f the head a n d neck d i d n o t s h ow a ny o b v i o u s s i g n o f a i rway obstructio n , i t s h owed a n i n c rease prevertebra l soft tissue (swe l l i ng o f the pos­ terior p h a ryngeal wa l l) (a rrow), an i m porta nt d i a g n ostic s i g n of 2 retro p h a ryngeal a bscess.1 There was a l so a loss of n o r m a l l o rdotic cu rva tu re of the s p i ne.

• How Do You Assess the Severity of Ai rway

Obstruction?

Airway obstruction is assessed clinically by history and physical examination. Oxygen saturation, respiratory rate, stridor, tra­ cheal tug, intercostal indrawing, and use of accessory muscles are assessed and changes are noted. Lateral x-ray (Figure 28-2) and CT scan of the head and neck can quantify the degree of obstruction. Skilled providers may also be able to assess airway obstruction with ultrasound. Nasopharyngoscopy is particu­ larly useful in that it allows for a dynamic assessment of the obstruction. However, due to the risk of sudden deterioration in this patient with severe stridor, a clear airway management plan should be articulated with the team prior to proceeding with nasopharyngoscopy.

AI RWAY MANAGEMENT • What Are the Ind ications for Establishing a

Defin itive Airway in Patients with Deep Neck Infections?

Indications for definitive airway management in these patients are impending or anticipated progression to airway obstruc­ tion. The decision to secure the airway should ideally be made in consultation with the ENT surgeon. There is some evidence that it may be prudent to intervene at an earlier stage in at­ risk patients such as the diabetic.4 In some instances the ED physician may be forced into airway intervention if the patient is acutely decompensating. Once the decision to intervene is made, anesthesia and ENT consultants, if not already involved,

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should be immediately consulted. These patients are ideally managed in the operating room, provided that the transfer is quick and complete airway obstruction is not imminent. • What Was the Plan in This Case?

Given the severity of the obstruction and the patient's worsen­ ing symptoms the decision was made to establish a definitive airway. Anesthesia was immediately consulted and the plan was made to proceed to the operating room for definitive airway management, followed by surgical drainage of the abscess. • Do These Patients Req uire a Primary Surgical

Airway or Can an Attem pt be Made to I ntubate From Above?

Once the need to secure the airway has been established, the next decision is whether to attempt intubation from above (either oral or nasal) or to go directly to a surgical airway. In the "stable" patient, this generally refers to an awake trache­ otomy done by an experienced surgeon. Local anesthesia with minimal sedation (e.g. , remifentanil 0 .05-0. 1 flg·kg- 1 ·min- 1) is usually all that is needed to ensure patient cooperation when the procedure is performed by a competent surgeon. In rare circumstances, an awake cricothyrotomy may be indicated if surgical expertise or time is not available. The choice of airway should be a joint decision of the anesthesia practitioner and surgeon based on the predicted difficulties of each of the fol­ lowing: BMV, EGO ventilation, direct laryngoscopic intuba­ tion, alternative intubation, and surgical access. The skill and experience of the airway team will also affect this decision. In a review by Potter et al. , 13 the investigators found that primary surgical airways appeared to be favored by otolaryngologists, while oral and maxillofacial surgeons favored oral or nasal intubation. • Discuss the "Double Setup" and Plan C

In many cases, it will be reasonable to make a nonsurgical attempt to secure the airway. The specific route (awake, asleep, oral vs. nasal) will be discussed below. But it is critical to have a well-developed Plan B (and sometimes Plan C) . The "Double Setup" is the recommended approach for most of these cases, meaning that the surgical team is ready to go should attempts fail to secure the airway from above by the anesthesia practi­ tioner. This may involve having the surgical team gowned and gloved, and the neck prepped. Many times a formal trache­ otomy can be performed. But in the event of serious emergency airway compromise, a cricothyrotomy is the better choice. The surgical airway typically represents Plan B and this may solve the airway problem. Surgical access could, however, prove difficult for any of the reasons discussed above. Loss of the airway during tracheotomy has been reported14 and such an eventuality must be prepared for with "Plan C." This will typi­ cally involve an awake patient breathing spontaneously with sedation (IV or inhalation) to facilitate patient cooperation, but in rare circumstances could require muscle relaxation and an attempt to optimize direct laryngoscopy while attempts at obtaining surgical access continue.

• Discuss the Pros and Cons of Secu ring the

Ai rway in the Awake or Anesthetized Patient

One must decide whether to perform tracheal intubation awake or asleep. As discussed above, these patients invariably have fea­ tures that pose problems in airway management. The safest ini­ tial approach with these patients is to manage the airway while they are awake. Sedation may indeed be necessary in some cases, but it is preferred to keep the patient cooperative and spontaneously breathing. Ketamine (0. 5-1 mg·kg- 1), low-dose remifentanil (0.05-0 . 1 flg·kg- 1 · min- 1), or dexmedetomidine (0. 5-1 flg·kg- 1 over 1 0 minutes) may prove useful. Medication however does not replace the need for repeated reassurance and a confident demeanor on the part of the practitioner. The patient will typically need to be maintained in a sitting or semi­ sitting position in order to help preserve the airway, this will increase comfort and help ensure the patient's cooperation. • Discuss Reasons Why an Awake I ntubation

May be U nsuccessfu l

While awake intubation remains the safest initial approach to airway management, it is important to realize that sudden deterioration with a complete airway obstruction may occur even in a fully awake or minimally sedated patient. 1 5 -17 Reports of complete airway obstruction and some of failed broncho­ scopic intubation emphasize the importance of managing these patients under "double setup." 1 8 Inadequate airway anesthesia, care-provider inexperience, over-sedation, copious secretions, bleeding, are all reasons an awake intubation could fail. • What Is the Plan if Awake I ntubation Fails or

Is Not an Option?

If an awake intubation fails or is not possible, then a complete, but rapid, reassessment of the situation is in order. The next safest approach may be an awake surgical airway, provided that the patient still has a patent airway and is at least minimally cooperative. In the rapidly deteriorating or actively uncoopera­ tive patient, a primary surgical airway may not be a practical alternative. It may then become necessary to induce general anesthesia in a patient with multiple predictors of difficulty, certainly a less than ideal circumstance. • Discuss Options if General Anesthesia

Becomes Necessary to Secu re the Airway

Should it be necessary to induce general anesthesia, the "ideal" approach is a matter of opinion. There are "pros and cons" to all of the available choices. Induction of general anesthesia in this setting should always be done under "double setup" as discussed above. Perhaps the classic approach is an inhalation induction in an attempt to induce general anesthesia while preserving spon­ taneous ventilation. Inhalation induction followed by direct laryngoscopy and intubation is a common practice in children with airway obstruction since awake intubation is rarely a prac­ tical option in children. Inhalation induction of adults with airway obstruction may be more difficult in that the relatively longer excitement phase predisposes to aspiration, laryngospasm, or both. As anesthetic

Ai rway M a n a g e m e n t in a Patient with a Deep Neck I nfection

depth increases, complete airway obstruction can also occur due to the loss of muscle tone. Inhalation induction typically requires at least some degree of patient cooperation but can be accomplished without. 19 As with awake intubation, it is critical to have a well-rehearsed back-up plan (Plans B and C) . Preservation of spontaneous ventilation under anesthesia may also be accomplished utilizing IV agents. Compared to inhalation agents, it may be more difficult to preserve adequate spontaneous ventilation and achieve adequate depth of anes­ thesia using IV agents. Recent evidence suggests that remifen­ tanil may be a more attractive IV sedation option. Machata et al. 20 have demonstrated excellent intubating conditions when remifentanil was used for conscious sedation. A bolus of 0.75 flg·kg- 1 followed by an infusion of 0.075 flg·kg- 1 - min-1 provided good intubating conditions. Rapid sequence intubation (RSI) should not be a first-line management option in these patients. However, in the event that the airway is completely lost, consideration should be given to use of muscle relaxants to facilitate intubation while attempts continue to achieve surgical airway access. RSI may also be considered for the actively uncooperative patient pro­ vided there is a double setup. • Discuss the Pros and Cons of "Nasal or Oral"

I ntubation

Following the decision to attempt intubation from above, the next decision is whether to use the nasal or oral route. Each has its advantages and drawbacks. The nasal route bypasses the tongue (which may be swollen) and often provides a convenient passage to the glottic open­ ing. At one time, blind nasal intubation was a common choice in these patients, but with the general availability of flexible bronchoscopes (FB), this technique is now seldom indicated. Furthermore, blindly advancing the endotracheal tube (ETT) into the glottic opening may rupture the abscess with resultant soiling of the trachea. The risk of epistaxis is a potential concern with the nasal approach, as bleeding may hamper visualization and could trigger laryngospasm. The oral approach avoids the risks of nasal bleeding and tube size is limited only by size of the glottic opening. Oral intuba­ tion also allows for application and administration of high-Bow nasal oxygenation throughout the intubation process, which may prevent or delay the onset of hypoxemia. 2 1 Unfortunately, the massive tongue swelling combined with trismus, often seen in patients with Ludwig's, can make an oral intubation impossible. • How Can One Minimize the Risk of Bleeding

Associated with Nasal I ntu bation?

The risk of bleeding during nasal intubation can be minimized with the liberal use of topical vasoconstrictors (e.g. , xylometazo­ line) and by using a small ETT (7.0 mm inner diameter [ID] or smaller) . Reinforced ETTs are more flexible and may cause less trauma and are therefore preferable in these patients. Regular ETTs (including Nasal RAE ETTs) may be made less damaging to tissues by softening the tubes in warm saline prior to use. The practice of "dilating up the nasal passage" using differ­ ent sizes of nasopharyngeal airway may also decrease bleeding

and allow for passage of a larger tube. 22 Following application of local anesthesia and vasoconstrictors, a small soft nasal air­ way lubricated with 2o/o lidocaine jelly can be inserted into the right nasal passage (larger in most people) . If resistance is encountered, the left nares can be tried. The process can then be repeated with the next larger size airway. The goal is to get easy passage of at least a size 8 nasal airway. An ETT a half size smaller can then be used for the intubation. A larger tube (7.0-mm ID or greater) is advantageous in that it allows for insertion of the adult FB with its superior optics and suction capabilities. • What Is the Best Tool to Facilitate

I ntubation?

For the most part, the tool that one chooses to facilitate intu­ bation in these patients is less important than the approach discussed above. The technique chosen should reflect the practi­ tioner's skill, experience, and comfort with the technique, as well as the safety and practicality of the chosen technique. Nonvisual techniques are discouraged due to risks of soiling the airway and of possible laryngospasm. For reasons discussed earlier, tech­ niques that allow visualization of the airway are preferred, usu­ ally a direct-vision laryngoscopy, an indirect-vision laryngoscopy (using a video-laryngoscope or the FB) . Other methods may be acceptable provided the practitioner is skilled in their use. • Discuss the Advantages and Disadvantages

of Flexi ble Bronchoscopic I ntubation (FBI)

FBI offers the advantage of being able to visualize and navi­ gate "around the obstruction" and is usually well tolerated in the awake patient. Unfortunately, heavy secretions, bleeding, or both, may limit the usefulness of the FBI. In addition, as the ETT is advanced blindly over the bronchoscope during intuba­ tion, careful attention is required to avoid rupturing the abscess and soiling of the infective materials into the trachea. Use of the adult FBI can lessen the effect of secretions compared to the pediatric FBI but necessitates the use of at least a size 7.0-mm ID ETT. FBI may be more difficult in the unconscious patient with decreased muscle tone but if attempted may be best done in combination with a video-laryngoscope. 23 • Discuss the Advantages and Disadvantages

of Di rect Laryngoscopy

Direct laryngoscopy will often be advantageous in the presence of heavy secretions. It can be performed quickly and is gener­ ally the technique of choice in the unconscious patient. Direct laryngoscopy is highly stimulating and may not be tolerated in the awake patient, particularly if much force is needed to expose the glottis. • Describe the Plan to Secu re the Ai rway in

Th is Case

In the operating room, the airway was reevaluated and, in consultation with the ENT surgeon, the decision was made to perform an awake nasal tracheal intubation using an FB under "double setup."

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Ai rway M a n a g e m e n t in the E m e rg e n cy Room

The patient was positioned semi-sitting and standard moni­ tors were applied. Supplemental oxygen was delivered with nasal prongs during preparation and airway anesthesia. A low-dose infusion of remifentanil (0.05 flg·kg- 1 - min- 1) was administered intravenously to reduce the patient's anxiety and improve cooperation. The neck was prepped and the surgical team was gowned and gloved, and ready to perform an emer­ gency surgical airway (Plan B) . • Discuss Ai rway Anesthesia for Patients with

Ludwig's Angina

There are multiple techniques to anesthetize the airway and these are discussed in details in Chapter 3. The chosen tech­ nique depends largely on of the preference of the practitioner. However, care must be taken to avoid early stimulation of the airway which can result in fatal laryngospasm. 10 Inflammation and infection can, in theory, decrease the effi­ cacy of local anesthetics due to changes in local pH. However, this is generally not of any clinical significance. Heavy secre­ tions, bleeding, or both, can decrease the amount of local anes­ thetic that actually reaches the mucosa and this should be taken into account, but there are many reports of successful airway anesthesia in the presence of infection. 24 • How Was Airway Anesthesia Achieved

in Th is Case?

Airway anesthesia was achieved with a combination of lidocaine ointment and inhaled lidocaine. Xylometazoline (Otrivin Nasal Spray, Novartis Consumer Health Canada Inc., Mississauga, ON) was applied to both nasal passages in hopes of decreas­ ing bleeding potential. Approximately 2.0 em of 5% lido­ caine ointment was applied to the back of the tongue with a tongue depressor. The EZ Spray 1 00 atomizer (Alcove Medical Corporation, Houston, TX) was then used to deliver 1 5 mL of 4% lidocaine. No attempts were made to specifically block the superior laryngeal nerve due to the possibility of disrupting the abscess and potentially soiling the airway. • How Was Th is Patient's Airway Secured?

The patient was asked to take a deep breath while occluding each nares. The right appeared more patent and was dilated as described above (see section "How Can One Minimize the Risk of Bleeding Associated with Nasal Intubation?" in this chapter) so that a #8.0 nasal airway was easily accepted. A #7.0 rein­ forced ETT was then gently advanced into the nasopharynx. An adult 5 .2-mm FB was then passed through the ETT. After identifYing the glottic opening, which was significantly devi­ ated to the left, the bronchoscope was directed into the tra­ chea until the carina was in view and the ETT was then gently advanced into the trachea over the bronchoscope. Following the end-tidal C0 confirmation of successful tube placement, 2 general anesthesia was induced with fentanyl and propofol. Surgical drainage of the abscess was then accomplished with­ out incident. Following 36 hours of ventilation in the ICU, tra­ cheal extubation took place uneventfully and the patient made a full recovery.

S U M MARY It is clear that there is more than one approach to the manage­ ment of the airway in these patients. The choice will be based on the particular patient presentation and the skills and experi­ ence of the airway team. In 2002, Jenkins et al. 2 5 surveyed the management choices for the difficult airway by Canadian anesthesia practitioners. Regarding the management of a patient unable to swallow due to a retropharyngeal abscess, 70% chose an awake approach, 23% chose inhalation induction, and only 7% chose an IV induction of anesthesia. While 37% chose direct laryngoscopy and 8% chose primary surgical airway, FBI was the initial tech­ nique chosen by 50% of the responders. A 2004 study by Bross­ Soriano et al.3 reported on 1 07 patients with Ludwig's angina over 1 8 years. Surgical airway was required in 28%, when nasal intubation failed or was not possible. Deep neck infections with abscess formation resulting in airway compromise provide challenges for both the airway practitioner and the surgeon who are dependent on each other for a successful outcome. The likelihood of a satisfactory result is enhanced by early involvement of the team planning an approach to such challenges.

REFERENCES 1. Mathew GC, Ranganathan LK, Gandi S, et al. Odontogenic maxillofacial space infections at a tertiary care center in North India: a five year retro­ spective study. int} infect Dis. 20 1 2 ; 1 6:296-302. 2. Parhiscar A, Har-EI G. Deep neck abscess: a retrospective review of 2 1 0 cases. Ann Otol Rhino! Laryngol. 200 1 ; 1 1 0 : 1 0 5 1 - 1 054. 3. Bross-Soriano D, Arrieta-Gomez ], Prado-Calleros H . Management of Ludwig's angina with small neck incisions: 1 8 years of experience. Otolaryngol Head Neck Surg. 2004; 1 30 (6) : 7 1 2-7 1 7. 4. Boscolo-Rizzo P, Da Mosco MC. Submandibular space infection: a poten­ tially lethal infection. IntJ Infect Dis. 2009; 1 3 :326-333. 5 . Mayor GP, Millan JM, Vidal AM. Is conservative treatment of deep neck space infections appropriate? Head Neck. 200 1 ;23(2) 1 26- 1 33. 6. Sichel J, Dana I, Hoewald E, et al. Nonsurgical management of para­ pharyngeal space infections: a prospective study. Laryngoscope. 2002; 1 1 2: 906-9 1 0 . 7 . Dumbarton TC, Hung OR, Kent B. Overinflation of a King-LT extra­ glottic device mimicking Ludwig's angina. Anesth Analg Case Rep. 2 0 1 6;6(4) :80-83. 8. Pathak R, Supplee S, Aryal MR, et al. Warfarin induced sublingual hema­ toma: a Ludwig angina mimic. Am} Otol. 2 0 1 4;36 ( 1 ) 84-86. [Epub ahead of print] . 9. Neff SPW, Merry AF, Anderson B. Airway management in Ludwig's angina. Anaesth intensive Care. 1 999;26:65 9-66 1 . 1 0 . Brimacombe J , Perry A, Van Duren P. Use o f a size 2 LMA to relieve life-threatening hypoxia in an adult with quinsy. Anaesth intensive Care. 1 993;2 1 :475-476. 1 1 . Narendra PL, Vishal NS, Jenkins B. Ludwig's angina: need for includ­ ing airways and larynx in ultrasound evaluation. BMJ Case Rep. 2 0 1 4 . Doi: 1 0. 1 1 36/bcr-20 1 4-206506. 12. Wholey MH, Bruwer AJ, Baker HL Jr. The lateral roentgenogram of the neck, with comments on the atlanta-odontoid-basion relationship. Radiology. 1 95 8 ; 7 1 :3 50-356. 1 3 . Potter JK, Herford AS, Ellis E. Tracheotomy versus endotracheal intu­ bation for airway management in deep neck space infections. J Oral Maxillofoc Surg. 2002;60:349-354. 14. McGuire G, El-Beheiry H, Brown D. Loss of the airway during tracheos­ tomy: rescue oxygenation and re-establishment of the airway. Can } Anesth. 200 I ;48 (7)697-700. 1 5 . Ho AMH, Chung DC, To EWH, et al. Total airway obstruction during local anesthesia in a non-sedated patient with a compromised airway. Can j Anesth. 2004; 5 1 : 8 838-84 1 .

Ai rway M a n a g e m e n t in a Patient with a Deep Neck I nfection 1 6. Shaw lC, Welchew EA, Harrison BJ, et a!. Complete airway obstruction during awake fiberoptic intubation. Anaesthesia. 1 997;52: 576-5 8 5 . 1 7. McGuire G, EI-Beheiry H. Complete upper airway obstruction during awake fiberoptic intubation in patients with unstable cervical spine frac­ tures. Can } Anesth. 1 999;46 (2) 1 76- 1 78. 18. Pahl C, Yarrow S , Steventon N, et a!. Angina bullosa haemorrhagica pre­ senting as acute upper airway obstruction. Br} Anaesth. 2004;92:283-286. 1 9. Smith CE, Fallon WF. Sevoflurane mask anesthesia for urgent tracheos­ tomy in an uncooperative trauma patient with a difficult airway. Can j Anesth. 2000;47(3) :242-245 . 2 0 . Machata AM, Gonano C, Holzer A , e t a!. Awake nasotracheal fiberoptic intubation: patient comfort, intubating conditions, and hemodynamic stability during conscious sedation with remifentanil. Anesth Analg. 2003;97(3): 904-908. 2 1 . Weingart SO, Levitan RM. Preoxygenation and prevention of desat­ uration during emergency airway management. Ann Emerg Med. 20 1 2 ; 5 9 (3): 1 65 - 1 75 . 2 2 . Hall CE, Shutt LE. Nasotracheal intubation for head and neck surgery. Anaesthesia. March 2003; 5 8 (3):249-256. 23. Sharma D, Kim LJ, Ghodke B, Airway Management with Combined Use of Glidescope• Videolaryngoscope and Fiberoptic Bronchoscope in a Patient with Cowden Syndrome. Anesthesiology.. 20 1 0; 1 1 3253-25 5 . 24. Ovassapian A , Tuncbilek M, Weitzel E , et a!. Airway management i n adult patients with deep neck infections: a case series and review of the literature. Anesth Analg. 2005 ; 1 00(2) : 5 85-589. 25. Jenkins K, Wong DT, Correa R. Management choices for the difficult airway by anesthesiologists in Canada. Can J Anesth. 2002;49 (8) : 8 5 0-856.

SELF - EVALUATION QU ESTIONS 2 8 . 1 . What i s Ludwig's angina? A. epiglottitis B. unstable angina

C. deep neck infection and edema involving the entire floor of the mouth D. lingual tonsillitis E. mediastinitis 28.2. Which of the following airway management strategies may be difficult in patients with a Ludwig's angina? A. face-mask ventilation B. ventilation using extraglottic devices C. direct laryngoscopy D. surgical airway E. all of the above 2 8 . 3 . Which of the following is NOT an acceptable intubating technique in managing patients with Ludwig's angina? A. surgical airway B. flexible bronchoscopic intubation C. intubation using an intubating LMA D. laryngoscopic intubation E. intubation using a GlideScope'"

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C H A PT E R 2 9

Unique Airway I ssues in the Inten sive Care Unit Shawn D. Hicks , J. Adam Law, and Mich ael F. Murphy

CAS E PRESENTATION

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CASE PRESENTATION A 56-year-old male was the driver of a motorcycle involved in a motor vehicle crash. The primary survey performed by the trauma team reveals the patient to have a patent airway, with spontaneous breathing and clear, bilateral breath sounds. His circulation is normal with strong pulses present in all limbs and no signs of external hemorrhage. His Glasgow Coma Scale is 14 of 1 5 due to slight confusion. Secondary survey reveals rib fractures on the left and several orthopedic injuries including a broken tibia and femur on the left as well as a pelvic fracture. Several hours after the injury, the patient is brought to the oper­ ating room (OR) for surgical repair of the long bone fractures and external fixation stabilization of the pelvic fracture under general anesthesia. He is admitted to the ICU immediately after the surgery, and is extubated uneventfully shortly thereafter. For the first 2 days after the injury, the patient has required high doses of opioids to control his pain from the rib fractures. Late in the evening of the third postoperative day, he spikes a temperature of 3 8 .9oC, and is having trouble clearing his secretions with

coughing. His respiratory rate is 32 per minute; his oxygen saturation is 92% on a non-rebreather face mask (NRM); his heart rate is 1 2 0 beats per minute and his blood pressure is 1 60/8 5 . He is complaining of dyspnea and severe pain. The patient looks tired and has obvious use of accessory muscles of respiration. A chest radiograph reveals volume loss and airspace disease with air bronchograms in the right lower lobe but no pneumothorax. The house staff is alerted by the patient's nurse. A first-year resident is on call with a senior fellow in critical care medi­ cine (CCM) . After their assessment and discussion with the attending staff by telephone, the house staff team proceeds with endotracheal intubation. Based on the examination of the air­ way, no difficulties are anticipated with the tracheal intubation itself. The respiratory therapist prepares the usual equipment while oxygen is administered by NRB . The resident physician administers 2 mg of midazolam and with the patient placed in semi-Fowler position at 45 degrees, makes an attempt at intu­ bation using direct laryngoscopy (DL) under the supervision of the senior fellow. The first attempt results in an esophageal intubation. Oxygen saturations dip into the high 80s. After repositioning the patient's head and neck, and recovery of the saturations into the low 90s this time employing a bag-mask unit with high-flow oxygen, a second attempt is performed by the resident. Despite using a tracheal introducer (also known as "gum-elastic bougie") and the BURP maneuver, the attempt is again unsuccessful. A third attempt at tracheal intubation is made by the CCM fellow following the administration of propofol 1 00 mg and succinylcholine 1 2 0 mg, but this also fails. After this intuba­ tion attempt, it becomes more difficult to manually ventilate the patient using bag-mask. It is unclear if this is because neuromuscular function has returned or if it is related to dete­ riorating lung compliance. The patient needed several boluses of vasopressor to treat hypotension during this last intubation attempt, probably related to high bag-mask-ventilation (BMV)

U n i q u e Ai rway I ssues in the I nte nsive Ca re U n it

pressures coupled with the circulatory effect of the propofol. Recognizing the seriousness of the situation, the CCM fellow requests that some more airway equipment be made available in the event that they cannot secure the airway. The respiratory therapist reports that some of the difficult airway equipment is down the hall in a locked room, and that he needs to leave to acquire the items requested. None of the staff involved in the resuscitation are aware of what exactly is available on this cart, but clearly, not having it in the room from the beginning was an error in j udgment. The fellow now requests that the anesthesia team be called to assist with securing the airway. A video-laryngoscope is brought from the OR by a senior anesthesia resident and is used to successfully intubate the trachea of the patient. Video­ laryngoscopy reveals significant swelling of the supraglottic structures and vocal cords. Those involved in the care of this patient recognized that this situation could have had a more negative outcome. A multidisciplinary meeting was scheduled to debrief and review options for improving their approach to airway management in the ICU employing a root cause analysis (RCA) methodology and intended to implement systematic changes that are preven­ tative in nature.

I NTRODUCTION • Is Airway Management in the ICU

Associated with More Complications Compared to the OR?

Airway management outside the controlled OR environment carries higher risk to the patient for a variety of reasons includ­ ing the acuity of the situation, the patient's limited physiologic reserve, and less access to advanced airway equipment. In addi­ tion, airway management is often performed by practitioners with limited experience, commonly after regular working hours when more experienced help may be harder to summon. 1 Perhaps the most common indication for out o f the OR but in hospital airway management is cardiac arrest. It is known that cardiac arrest outside of the OR occurs frequently. 2 Furthermore, the incidence of cardiac arrest in the ICU setting is as high as 2%, much higher than the 0.068% rate in the OR.3 Chacko et al.4 reported on critical incidents in a closed 1 8-bed, multidisciplinary unit over a 33-month period. Airway-related incidents accounted for 32.8% of all reported incidents, with the most common being accidental extubation. In this study, there were 32 incidents ( 1 1 .4% of those reported) that led to adverse outcomes, including 4 deaths, all of which were due to airway-related events. Needham et al. 5 reported on factors which contributed to airway events that had been collected as part of the Intensive Care Unit Safety and Reporting System, a voluntary anony­ mous reporting system developed in conjunction with the Society of Critical Care Medicine and used in 1 8 ICUs across the United States over a 1 2-month period. There were 84 1 incidents reported with 78 airway events. More than half of the airway events were considered preventable and about 20% of the patients with airway reports sustained a physical injury

and had an actual or anticipated prolonged hospital length of stay associated with the event. There was one death related to an airway event. Additionally, family dissatisfaction was com­ mon when these events occurred. Factors noted to limit adverse airway events included adequate ICU staffing and the use of skilled assistants. The Fourth National Audit Project of the Royal College of Anaesthetists and Difficult Airway Society (NAP4)6 reported a significantly higher rate of serious airway complications occur­ ring in the intensive care unit (ICU) compared to the OR. In 61 o/o of the ICU cases reported to NAP4, these complications led to death or persistent neurological injury, in contrast to 33% of cases reported from emergency departments and 1 4% of the 0 R cases. In addition, NAP4 also identified that 70% of the cases and 60% of the deaths in ICU involved complications of trache­ otomy. In this audit, airway events in the ICU were more likely to occur after hours, and be managed by a clinician with less anesthesia experience. Further review of these cases revealed defi­ ciencies that included poor identification of high-risk patients, poor or incomplete planning, and inadequate provision of skilled staff and equipment to manage the events. • Why Are Airway I nterventions in the ICU

More Dangerous?

Patients admitted to the ICU generally have limited physi­ ologic reserve. They need minute-to-minute monitoring and treatment and usually require respiratory and/or hemodynamic support. Physicians choosing to practice in the ICU environ­ ment must possess excellent airway management skills for a variety of reasons. Some patients initially without tracheal intu­ bation will decompensate while in ICU and require tracheal intubation. Others are admitted to the ICU having been intu­ bated elsewhere and will be extubated (planned or unplanned) during their ICU stay. Still others, having been extubated, will fail and require reintubation. As with any intervention, an understanding of the dynamic and often subtle interplay berween commonly utilized medications and the physiologic reserve of the compromised patient must be understood. A particular risk is the patient presenting to the ICU with "severe dyspnea'' which is related to severe metabolic acidosis (e.g., ethylene glycol, methanol, or salicylates) . Often, the patient is thought to be anxious. Obviously, the administration of seda­ tive agents or opioids in these patients is a recipe for disaster. Denitrogenation is more difficult in the critically ill patient population, making oxygen desaruration during airway man­ agement a common adverse event. Oxygen desaturation is associated with serious complications such as cardiovascular col­ lapse, global hypoxia related brady-asystolic arrest, dysrhythmias, neurologic inj ury, or death. There are important physiological reasons for such limited respiratory reserve: •

•

increased oxygen consumption in the critically ill patient leads to reduced safe apnea time and an increased alveolar­ arterial gradient makes the saturation of hemoglobin less efficient with a given functional residual capacity7; this is compounded by an increased shunt fraction in some patients related to diffusion block (e.g. , pulmonary edema) and reductions in functional residual capacity (FRC) ;

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predictable reduction in FRC related to obesity, position (increased closing capacity) , lung disease, etc. attenuates safe apnea time even further. Several strategies may be employed in improving denitroge­ nation and prolonging the safe apnea period. These include8: •

•

•

•

positioning the patient in a semi-recumbent position; continuous nasal cannulae at 10 to 1 5 Lmin- 1 ; noninvasive ventilation i f oxygen saturations are 9 0 % o r less, titrating PEEP to between 5 and 1 5 em H 0; 2 use of a PEEP valve during BMV to augment the patient's tidal volume.

Preemptive or continuing use of Transnasal Humidified Rapid-Insufflation Ventilatory Exchange (THRIVE)9 (e.g., OptiBow•) should be considered. Simple high-Bow nasal oxy­ genation does not assist with ventilation in apneic patients and therefore arterial carbon dioxide concentrations will rise at a predictable rate. However, the OptiBow© system has been shown to provide some degree of ventilation, as measured by slower rise of carbon dioxide over time. Denitrogenation should be provided for at least 3 minutes, situation acuity permitting. Delayed sequence intubation (DSI) 10 employing ketamine titration balancing continued patient ven­ tilation with CNS obtundation has been used successfully in critically ill patients to aid the denitrogenation process. Hypotension at the time of intubation is more common in critically ill patients and is associated with an increased mortal­ ity. Risk factors associated with an increase in post-intubation hypotension are septic shock, renal failure, respiratory failure, and increased age. 1 1 Right ventricular failure is an especially dif­ ficult condition to manage should it preexist, or result from the acute respiratory event. Several strategies are useful in addressing this important complication: ensuring patent intravenous access, assessing the need for a Buid bolus prior to intubation (in the absence of pulmonary edema) , having vasopressor therapy imme­ diately available and in some cases preemptively administered as a bolus at the time of induction or by continuous infusion. In addition to limited cardiopulmonary reserve, other important concerns, such as hepatic and renal dysfunction, a "full stomach'' (e.g. , patients on continuous tube feeding) , and altered neurological function are also common in this patient population. It is not uncommon in the ICU population for patients to be extubated and then need to be reintubated at a later time in their care. A prospective database of 1 05 3 ICU intubations revealed that subsequent intubations have an even higher risk of complications compared to the first intubation. 1 2 This increase in complications occurred without there being a measurable increase in predicted technical difficulty. The main complica­ tions were hypotension and hypoxemia. This study highlights the importance of recognizing that these patients are at higher risk of these complications and the need to strive to avoid them with proper preparation. Intensive care patients are as complex as the environment in which they are cared for. The practitioner tasked with airway man­ agement in this setting must be aware of these factors and make sound decisions, often very quickly, to improve patient outcome.

• How Can We I mprove Outcomes Related to

Ai rway I nterventions in the ICU?

The literature clearly identifies the ICU population as a group of patients at higher risk of life-threatening complications related to airway interventions, but how can we improve out­ comes for these patients related to airway interventions? Several approaches have been identified to improve the culture of safety and optimize the care of airway emergencies outside the OR. Some institutions have organized a group of multidisciplinary experts to focus on improving safety and quality improvement with respect to airway management, such as one institution's so­ called DART (difficult airway response team) . 13 This approach focuses on safety monitoring, quality improvement, availability of equipment in key locations, an educational program, and a response team that is deployed in an anticipated or unantici­ pated difficult airway situation.

AI RWAY MANAGEMENT IN THE ICU • What Are the Pharmacologic Considerations

for Ai rway Management in the Critically I l l ?

Several o f the pharmacologic agents routinely used i n a n elec­ tive situation could be harmful to a critically ill patient with a limited reserve. A detailed discussion on the pharmacology of intubation can be found in Chapter 4. Much has been debated about the best pharmacologic approach to facilitate airway management in the critically ill. The important question is how to provide the best conditions for intubation with the least amount of risk. In particular, it is important to mitigate the hemodynamic swings that may result from these agents as well as to consider whether neuromuscular blocking agents should be used. In addition, several factors other than pharmacologic agents may contribute to severe hemodynamic instability in the critically ill patient (e.g. , institution of positive pressure venti­ lation [PPV] , especially in the presence of hypovolemia) . It is best to prepare for and expect hemodynamic instability associ­ ated with airway management in these patients regardless of the agents used by preemptively administering vasopressors by infusion or boluses depending on the situation. The ideal induction agent should provide good conditions for tracheal intubation without adversely impacting cardiac contractility or systemic vascular resistance. Etomidate has been used as an induction agent in the hemodynamically fragile patient because it is thought to have a favorable hemodynamic response compared to propofol. However, there is growing concern that use of even a single bolus of etomidate is associ­ ated with adrenal insufficiency and increased mortality. 14 When completed, the KEEP PACE trial, comparing ketamine with etomidate for inducing critically ill patients may shed some light on this question. 15 Another question is whether the use of neuromuscular blocking drugs (NMBD) to facilitate endotracheal intubation improves success rates and reduces complication rates in the critically ill population, as has been demonstrated in Emergency Medicine. 16 One side of the debate argues that NMBD will improve first-attempt success and thus reduce complications associated with repeated attempts at intubation. The other side

U n i q u e Ai rway I ssues i n the I nte nsive Ca re U n it

argues that proper personnel, training, and equipment may not be in place to handle an emergency complication of not able to ventilate and intubate. No matter the argument, evidence shows8 that depolarizing agents lead to more rapid desaturation in the apneic patient than non-depolarizing agents. The specu­ lation is that skeletal muscle fasciculations are responsible. The availability of sugammadex is likely to foster the replacement of succinylcholine by rocuronium in patients at risk of rapid desaturation. The ideal approach is to have the proper resources available in terms of trained staff and appropriate equipment to handle difficulties encountered in airway management regardless of the pharmacologic agents used. For a detailed discussion on the use of NMBD for intubation refer to Chapter 4.

blades (e.g., C-MAC. [used with Macintosh blade option] Karl Storz Endoscopy America, Inc. Culver, CA; GlideScope Titanium [used with MAC blade option] Verathon Inc., Bothell, WA) will provide the benefit of potentially improved visualization, allowing supervision during the intubation, generally straightforward endotracheal tube (ETT) delivery, and maintenance of DL-type laryngoscopy skills. The use of hypercurved (e.g., C-MAC. [used with D-Biade option] or hyperangulated VL blades (e.g. , GlideScope Titanium [used with LoPro blade option] ) can be reserved for the patient pre­ senting with more difficult laryngoscopic anatomy to further aid in laryngeal visualization, recognizing that tube delivery can be slightly more challenging with their use. • Who Should be Able to Respond to an

• What Equi pment Should be Available in the

ICU with Respect to Ai rway Management?

Having the appropriate equipment immediately available to those patients who may benefit the most from its use should be an important aspect of improving airway-related outcomes. Chapter 62 gives a detailed discussion of the difficult airway cart for environ­ ments outside of the OR. A multidisciplinary team may be useful in planning what equipment will be within immediate reach of the I CU. Considering these patients have a higher risk of having a dif­ ficult airway resulting in a life-threatening complication, it would be prudent to have advanced airway equipment immediately avail­ able. These include: airway adjuncts to facilitate ventilation (e.g., extraglottic devices) and tracheal intubation (e.g., tracheal tube introducer [bougie] ); alternatives to DL (video-laryngoscopes, intubating extraglottic devices) ; airway exchange catheters (AEC) ; and surgical airway equipment to facilitate cricothyrotomy. A 20 1 0 survey of iCUs in the United States revealed that many did not have a difficult airway cart and if present, the cart often did not have some of the items that should be mandatory. 17 Equipment for awake flexible bronchoscopic intubation should also be immediately available. Some have argued that awake tracheal intubation should be used more frequently in the critically ill patient, considering the increased risk of hypo­ tension and hypoxemia that may be associated with induction agents . 1 8 See Chapter 3 for detailed discussion on the how to perform an awake tracheal intubation. • Is There Any Advantage to the Use of Video-

Laryngoscopy in the Critical Care U n it?

Video-laryngoscopy (VL) may help facilitate tracheal intuba­ tion in the critical care setting. Beyond the standard benefit of a potentially improved laryngeal exposure over that provided by direct laryngoscopy, VL will allow an experienced airway manager to more effectively supervise a less experienced clini­ cian through the tracheal intubation process. Compared with DL, studies from the critical care setting have indicated an improved first-attempt success rate with the use of VL, 19-22 a lower esophageal intubation rate, 19'20 and in some studies, fewer complications. 1 9 If the resource is available, a recommendation can be made for the routine use of VL in critical care units. In particular, first-attempt use of VL with Macintosh-type

Ai rway Emergency?

One aspect of a quality improvement program is to bring a skilled clinician to the bedside. In an academic setting, an experienced clinician can quickly assess whether the situation is appropriate for the level of trainee that they are supervising. In many cases, house staff in the ICU are residents from other medical specialties that do not get basic training in airway man­ agement (nor will they need to in their base specialty) . Airway management in many patients in the ICU will not be appropri­ ate for a trainee that has not mastered basic and some advanced airway management skills, even in a nonurgent setting.

OTH E R CO N S I D E RATIONS • What Educational Techniques Could be

Employed to Facilitate Competency in the ICU Setting?

There are several components to learning how to manage an airway in a critically ill patient. Because these patients are at high risk of physiologic decompensation, it takes a skilled cli­ nician and team approach to immediately respond to a rapidly changing clinical situation. The trainee needs to become com­ petent with technical skills and nontechnical skills. Some of the technical skills are denitrogenation, optimizing the patient's head and neck position, manual bag-mask-ventilation, and endotracheal intubation. The nontechnical skills are related to situational awareness and crisis resource management. High fidelity simulation may be an ideal environment for these skills to be taught in a nonthreatening environment for the learner without any risk to a real patient. Teaching and simulation training has been covered in Chapter 64 of this book. Exposure to a cadaver training session has been shown to improve self-reported percent of glottis opening (POGO) scores by CCM fellows. 23 They were also able to report a 98% first-attempt success rate in the clinical setting following the session. In this report the critical care training program used five surgical grade cadavers with a different clinical scenario at each station to demonstrate a variety of anatomical challenges (spontaneously breathing in need of BVM assistance, cervical spine collar in situ, beard, full teeth, emesis or blood obstructed view, etc.) . Chapter 64 describes these models in detail.

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Multidisciplinary in situ simulation could also be an impor­ tant way to improve the qualiry and safery of airway management in the ICU. This exercise allows all team members, including nurses, respiratory therapists, and physician trainees to work together to improve their response to an airway management situation in the I CU. This type of simulation takes place in the actual clinical environment where team members use equipment and resources they have at hand in everyday practice. Wheeler et al. 24 described their experience with this type of simulation train­ ing and how it is useful in identifYing gaps in knowledge, threats to patient safery, and improve teamwork behaviors. 24 • How I m portant Is Troubleshooting the

Compl ications of Tracheotomy to the ICU Physician?

As noted in the section "Is Airway Management in the ICU Associated with More Complications Compared to the OR?" of this chapter, NAP4 identified that 50% of the cases and 60% of the deaths in ICU involved complications of tracheotomy.6 In ICU, planning should recognize that tracheotomies may inad­ vertently fall out. Tracheotomy displacement occurred most frequently in obese patients and during patient movement, dur­ ing sedation holidays (e.g. , sudden awakening and coughing or manually removing a tube) , or during airway interventions (e.g. , tracheal suction or nasogastric tube placement) . Further, delayed diagnosis of displacement, in the absence of capnography was reported repeatedly in NAP4, and it is not a new finding. 2 5 • What Is the Role for Waveform Capnography

in the ICU?

It can be categorically recommended that continuous waveform capnography be employed in ICU for all intubated and ven­ tilated patients. Further, capnography is now the standard of care for confirming correct tracheal placement of devices such as an endotracheal or tracheotomy tube, and that a flat trace in the newly arrested patient means that the device is NOT in the trachea unless confirmed by flexible bronchoscopy. NAP4 identified that the diagnosis of esophageal intubation was hampered by lack of capnography equipment.6 1hey further found that the misinterpretation of a flat capnograph when esoph­ ageal intubation occurred during cardiac arrest and attributed to circulatory arrest was incorrect. It has been recognized for many years that during cardiopulmonary resuscitation (CPR) capnogra­ phy is not flat but indicates a low concentration of expired gas. 26·27 • How Should a Tracheal Tu be Cuff Lea k be

Approached in the Critically I l l Patient?

ETT cuff leaks can occur in the intubated patient. This can lead to problems with mechanical ventilation and loss oflower airway pro­ tection against aspiration of secretions or gastric contents. In the critically ill patient, ETT exchange can be risky because of apnea intolerance from high Fi0 , PEEP or minute ventilation require­ 2 ments, or in those with new or normally difficult airway anatomy. An important first step in troubleshooting a presumed cuff leak is to confirm that the cause of leak is indeed non-remediable: one critical care study documented that of 1 8 ETT exchanges for a

putative cuff leak, in only seven cases was a defective tracheal tube cuff or pilot valve apparatus confirmed to be the source of the leak. 28 Other causes of apparent cuff leak include cephalad migra­ tion of the tube, cuff underinflation, inadvertent placement of an oro- or nasogastric tube through the glottis, or a mis-sized tracheal tube. 29 These findings suggest that before embarking on a poten­ tially risky tube change, diagnostic maneuvers such as VL should be considered, for example, to confirm that the cuff of the ETT is appropriately located below the glottis. If indeed an ETT does need to be exchanged due to a leak or other reason, considerations must be given to where (e.g., in the ICU or OR), how (should an AEC be used for ETT exchange? or, will safery be maximized by conversion to tracheotomy rather than risky ETT exchange?) , and by whom this will most safely occur. In the high-risk patient, ETT exchange over an AEC is recommended; when used, a higher first­ attempt success and lower complication rate has been shown when facilitated by VL rather than DL30 • How Should Tracheal Extubation Proceed

in the Critica l ly I l l Patient with a Difficult Ai rway?

Tracheal extubation should occur as soon as the patient is deemed ready with respect to gas exchange and has a level of consciousness sufficient to maintain upper airway patency, manage secretions, and protect the lower airway. If upper air­ way edema is suspected, additional evaluation of the larynx with nasopharyngoscopy, VL, or various cuff leak assessment maneuvers is recommended (see Chapter 30) . Without a doubt, there is a significant incidence of failure of extubation in the critically ill population. Therefore, the extubation of the ICU patient must be accompanied by a viable plan for reintubation. The plan should include an assessment of the anticipated dif­ ficulry of tracheal reintubation, together with an assurance that equipment and expertise for the reintubation is readily avail­ able. In addition, for the patient with suspected difficult airway anatomy (e.g., recently fused neck; suspected or known airway edema) , consideration should be given to extubation over an 1 1 or 1 4-Fr Airway Exchange Catheter· (AEC, Cook Critical Care) to be used as a placeholder to facilitate reintubation if needed. Thomas Mort studied 354 ICU and OR difficult airway patients who were extubated over an AEC.31 Fifry-four patients who required reintubation over the AEC were compared with 36 in whom the AEC had already been removed. First-attempt success for reintubation over the AEC was 87%, in contrast to 1 4% without an AEC in situ. Airway-related complications were also significantly less in the AEC group. For those reintubated over an AEC, in most cases, the failure of extubation occurred within 1 0 hours of the original extubation.31

S U M MARY Critically ill patients needing airway interventions are at higher risk for life-threatening complications. They are more likely to experience hypoxemia and hypotension during the time of tra­ cheal intubation. This is associated with an increased mortaliry and risk of serious anoxic injury. Specific clinical interventions can be used to minimize these complications. These include

U n i q u e Ai rway I ssues i n the I nte nsive Ca re U n it

careful positioning, denitrogenation, preloading with an intrave­ nous fluid bolus, and using vasopressor therapy when required. With respect to the case presented at the beginning of the chapter, several measures at the institutional level could be implemented to improve the quality of care provided by their team. The organization could focus on improving the avail­ ability of equipment immediately available to the team in the ICU. Educational programs can be implemented to improve the basic skill level of the house staff and multidisciplinary team members. In situ simulation can be a useful way to identify deficiencies in knowledge, equipment, and teamwork behavior. A DART could be formed to respond to airway emergencies outside of the OR with expertly trained clinicians.

REFERENCES 1. Boylan JF, Kavanagh BP. Emergency airway management: competence ver­ sus expertise? Anesthesiology. December 2008; I 09 (6) : 945-947. 2. Mort TC. The incidence and risk factors for cardiac arrest during emer­ gency tracheal intubation: a justification for incorporating the ASA guide­ lines in the remote location. ] Clin Anesth. November 2004; 1 6 (7) :508-5 1 6 . 3 . Olsson GL, Hallen B . Cardiac arrest during anaesthesia. A computer­ aided study in 250,543 anaesthetics. Acta Anaesthesiol Scand. November 1 988;32(8):653-664. 4. Chacko J, Raju HR, Singh MK, Mishra RC. Critical incidents in a multidisciplinary intensive care unit. Anaesth Intensive Care. June 2007;35(3):382-386. 5 . Needham OM, Thompson DA, Holzmueller CG, et al. A system factors analysis of airway events from the Intensive Care Unit Safety Reporting System (ICUSRS). Crit Care Med. November 2004;32 ( 1 1 ) :2227-2233. 6. Cook TM, Woodall N, Harper J, Benger J; Fourth National Audit P. Major complications of airway management in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society. Part 2: intensive care and emergency depart­ ments. Br J Anaesth. May 20 1 1 ; 1 06(5):632-642. 7. Mosier JM, Hypes CD, Sakles JC. Understanding preoxygenation and apneic oxygenation during intubation in the critically ill. Intensive Care Med. 20 1 7;43 (2) :226-228. 8 . Weingart SD, Levitan RM . Preoxygenation and prevention of desatura­ tion during emergency airway management. Ann Emerg Med. March 20 1 2; 5 9 (3) : 1 65 - 1 75 , e l 6 1 . 9. Patel A , Nouraei SA. Transnasal Humidified Rapid-Insufflation Ventilatory Exchange (THRIVE) : a physiological method of increasing apnoea time in patients with difficult airways. Anaesthesia. March 20 1 5 ;70(3):323-329. 10. Weingart SD. Preoxygenation, reoxygenation, and delayed sequence intuba­ tion in the emergency department. } Emerg Med. June 20 1 1 ;40(6) :66 1 -667. 1 1 . Heffner AC, Swords DS, Nussbaum ML, Kline JA, Jones AE. Predictors of the complication of postintubation hypotension during emergency airway management. ] Crit Care. December 20 1 2;27(6) : 5 87-593. 12. Elmer J, Lee S, Rittenberger JC, DarginJ, Winger D, Emlet L. Reintubation in critically ill patients: procedural complications and implications for care. Crit Care. January 1 6, 20 1 5 ; 1 9: 1 2. 13. Mark LJ, Herzer KR, Cover R, et al. Difficult airway response team: a novel quality improvement program for managing hospital-wide airway emergencies. Anesth Analg. July 20 1 5 ; 1 2 1 ( 1 ) : 1 27- 1 39. 1 4 . Albert SG, Ariyan S, Rather A. The effect of etomidate on adrenal func­ tion in critical illness: a systematic review. Intensive Care Med. June 20 1 1 ;37(6) : 90 1 -9 1 0. 1 5 . Smischney NJ, Hoskote SS, Gallo de Moraes A, et al. Ketamine/propo­ fol admixture (ketofol) at induction in the critically ill against etomidate (KEEP PACE trial) : study protocol for a randomized controlled trial. Trials. April 2 1 , 20 1 5 ; 1 6: 1 77. 1 6. Walls RM , Brown CAIII, Bair AE, Pallin DJ, Investigators NI. Emergency airway management: a multi-center report of 8937 emergency department intubations. J Emerg Med. October 2 0 1 1 ;4 1 (4) :347-354. 1 7 . Porhomayon J, El-Solh AA, Nader ND. National survey to assess the con­ tent and availability of difficult-airway carts in critical-care units in the United States. ] Anesth. October 20 1 0;24(5) : 8 1 1 -8 1 4. 18. Lapinsky SE. Endotracheal intubation in the !CU. Crit Care. June 1 7, 20 1 5 ; 1 9:258. 1 9. Hypes CD, Stolz U, Sakles JC, et al. Video laryngoscopy improves odds of first-attempt success at intubation in the intensive care

20.

21.

22.

23.

24.

25.

26.

27.

28. 29. 30.

31.

unit. A propensity-matched analysis. Ann Am Thorac Soc. March 20 1 6; 1 3 (3): 382-390. Kory P, Guevarra K, Mathew JP, Hegde A, Mayo PH. The impact of video laryngoscopy use during urgent endotracheal intubation in the critically ill. Anesth Analg. July 20 1 3 ; 1 1 7 ( 1 ) : 1 44- 1 49. Noppens RR, Geimer S, Eisel N, David M, Piepho T. Endotracheal intu­ bation using the C-MAC(R) video laryngoscope or the Macintosh laryn­ goscope: a prospective, comparative study in the !CU. Crit Care. June 1 3 , 2 0 1 2 ; 1 6(3):R1 03. Silverberg MJ, Li N, Acquah SO, Kory PD. Comparison of video laryn­ goscopy versus direct laryngoscopy during urgent endotracheal intubation: a randomized controlled trial. Crit Care Med. March 20 1 5 ;43(3):636-64 1 . Wise EM, Henao J P, Gomez H , Snyder J , Roolf P, Orebaugh SL. The impact of a cadaver-based airway lab on critical care fellows' direct laryn­ goscopy skills. Anaesth Intensive Care. March 20 1 5 ;43 (2) :224-229. Wheeler DS, Geis G, Mack EH, LeMaster T, Patterson MD. High­ reliability emergency response teams in the hospital: improving qual­ ity and safety using in situ simulation training. BMJ Qual Saf June 2 0 1 3;22 (6) : 5 07-5 1 4 . Thomas AN, McGrath BA. Patient safety incidents associated with airway devices in critical care: a review of reports to the UK National Patient Safety Agency. Anaesthesia. April 2009;64 (4) : 3 5 8-365. Deakin CD, Morrison LJ, Morley PT, et al. Part 8 : Advanced life sup­ port: 20 1 0 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science with Treatment Recommendations. Resuscitation. October 20 I 0;8 1 (suppl l ) : e93-e 1 74. Falk JL, Rackow EC, Wei! MH. End-tidal carbon dioxide concentra­ tion during cardiopulmonary resuscitation. N Eng! J Med. March I 0, 1 988;3 1 8 ( 1 0) : 607-6 1 1 . Kearl RA, Hooper RG. Massive airway leaks: an analysis of the role of endotracheal tubes. Crit Care Med. April 1 993;2 1 (4) : 5 1 8-52 1 . El-Orbany M , Salem MR. Endotracheal tube cuff leaks: causes, conse­ quences, and management. Anesth Analg. August 20 1 3; 1 1 7 (2):428-434. Mort TC, Braffett BH. Conventional versus video laryngoscopy for tra­ cheal tube exchange: glottic visualization, success rates, complications, and rescue alternatives in the high-risk difficult airway patient. Anesth Analg. August 20 1 5 ; 1 2 1 (2) :440-448. Mort TC. Continuous airway access for the difficult extubation: the efficacy of the airway exchange catheter.AnesthAnalg. November 2007; 1 05(5): 1 357- 1 362.

SELF - EVALUATION QU ESTIONS 29. 1 . What are the two most common complications associ­ ated with intubation in the ICU patient? A. dental injury and mucosal laceration B. dysrhythmia and hypertension C. hypotension and hypoxemia D. cannot intubate, cannot oxygenate 29.2. All of the following are reasonable approaches to a qual­ ity improvement program that may improve outcomes associated with intubations in the ICU EXCEPT A. practicing in situ multidisciplinary simulation B. difficult airway response team (DART) C. reviewing what airway equipment available in the ICU

IS

immediately

D. attending ICU Grand rounds 29.3. All of the following are reasons why hypoxemia/desatura­ tion is more common during airway interventions in the critically ill patient EXCEPT A. increased oxygen may decrease their drive to breath B. decreased functional residual capacity (FRC) C. increased arterial-alveolar gradient D. increased oxygen consumption

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Manage ment of Extubation of a Patient Fol lowin g a Prolon ged Period of Mechanical Ventilation Richard M. Cooper

CAS E PRESE NTATION

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EXTU BATION STRATEG I ES

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DEVICES TO ASS I ST EXTU BATION

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AI RWAY EDEMA .

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TECH N I Q U E O F REI NTU BATION . . . . . . . . . . . . . . . . . .

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TRAC H EAL EXTU BATION . . . . . . . . . . . . . . . . . . . . . . . . . 3 74 S U M MARY . . . .

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SELF-EVALUATION Q U ESTIONS . . . . . . . . . . . . . . . . . .

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CASE PRESENTATION A 60-year-old male with chronic obstructive lung dis­ ease, limited exercise tolerance, and new onset pneumonia required tracheal intubation because of hypoxemic respira­ tory failure. Optimal positioning for direct laryngoscopy (DL) performed by an experienced practitioner using a Macintosh 3 blade yielded a Cormack-Lehane (C/L) 3 view, despite external laryngeal pressure and head elevation. Intubation was achieved on the third laryngoscopy attempt with the aid of a tracheal tube introducer (commonly known as the bougie) . After 6 days of assisted ventilation, the patient was weaned to a Fi0 of 0 . 4 , positive end expi­ 2 ratory pressure of 5 em H 0, and pressure support of 5 em 2 H 0 . The pulmonary infiltrates were much improved. His 2 respiratory rate was 24 breaths per minute. A cuff-leak test was performed.

EXTU BATION STRATEG I ES • What Is a High-Risk Extubation?

Adverse respiratory events are more frequently associated with extubation than intubation yet until recently, extubation has received little attention.1·6 A stratification of the risk associated with extubation has been proposed,5•7 and although unsup­ ported by randomized clinical trials, the need for an extubation strategy has been advocated by expert panels.5•8·9 There are two dimensions to the risk of extubation: will the patient tolerate extubation and if not, how easily can the airway be managed. The extubation of patients with easily managed airways who are not physiologically compromised, can be regarded as low risk. At the opposite end of the risk continuum are those with difficult airways who are also physiologically challenged-these patients are higher risk? The space between is a zone of uncer­ tainty but it behooves the practitioner to be mindful and antici­ pate potential difficulties. Many patients fall somewhere along an extubation risk continuum and the practitioner must exercise judgment and strategize how best to minimize complications. Risk prediction is an inexact science. Regarding extubation failure, patients are at a greater risk if their work of breathing is increased, oxygenation or ventilation are marginal, dead space or C0 production are increased, airway obstruction is a pos­ 2 sibility, or the ability to protect their airway is compromised. Even under controlled conditions, prediction of the difficult airway suffers from moderate10 to poor1 1 sensitivity and speci­ ficity. When extubation fails and patients require emergency airway intervention, the additional difficulties include the lack of time, information, personnel, and equipment as well as the availability of and tolerance to medications that may facilitate ventilation and intubation. A previously easily managed airway may be quite difficult under such conditions. And one that had been difficult is very likely to be more difficult or worse. Examples include the patient in whom the larynx could not

M a n a g e m e nt of Extu bation of a Patient Fo l l ow i n g a Pro l o n g ed Period of Mec h a n ica l Ve ntilation

be seen (Cormack-Lehane view ::2:3), who required multiple attempts, practitioners, or techniques, those with airways that have subsequently become more difficult (e.g., neck swelling, airway edema, macroglossia) or in whom access is limited (e.g. , halo fixation, unstable neck, monitors, headboards, location) . For most patients, the risk of requiring re-intubation is low. The results of three studies involving nearly 50,000 patients presenting for a wide variety of surgical procedures indicated that only 0.09% to 0. 1 9% required reintubation. 1 2-14 Studies from the United States/5 Thailand/6 and Taiwan17 yielded similar findings. Patients with systemic inflammatory response syndrome, ascites, chronic pulmonary disease, and pneumonia were at greatest risk of requiring reintubation. 17 Certain surgi­ cal procedures such as panendoscopy and a variety of head and neck operations are associated with a risk of required reintuba­ tion approximately 1 0 times higher ( 1 %-3%) . 1 8-22 Patients in critical care units often have limited physiologic reserve, altered secretions, or an impaired capacity to protect their airways. In this group of patients, required reintubation is substantially higher still. 23-2 5 Furthermore, multiple intubation attempts in the intense care unit (ICU?6 or emergency department (ED?7 are associated with a higher incidence of serious adverse events. • What Strategies Can be Used for the

High-Risk Extu bation?

Intubation is a skill; extubation is an art. Timing and attention to detail are essential to ensure that airway control is not relin­ quished. For higher-risk extubations, it is especially important that every effort be taken to ensure that conditions are optimal. Extubation can be performed while the patient is deep or wide awake, though the former is rarely j ustified in the patient with a difficult airway. Optimal conditions include oxygenation, ven­ tilation, the ability to clear secretions, and protect and maintain patency of the airway. Even when such conditions are optimal, reintubation may be required. Assessment of the airway prior to removing the endotracheal tube (ETT) might include: •

•

•

Laryngoscopy with the ETT in situ-this is of limited value and unlikely to reveal the extent of periglottic edema or vocal cord movement. Direct visualization of the tube in situ does not ensure that laryngoscopy after extubation will afford the same view. 2 8 Such an examination may be appropriate when other airway injuries are of concern. Laryngeal examination adjacent to the ETT using a flexible bronchoscope (FB) has some of the same limitations as laryngos­ copy. 29·30 Alternatively, an FB can be positioned within the ETT, and as the latter is withdrawn, an effort can be made to inspect the airway below and above the vocal folds. Unfortunately, this technique often fails. As the ETT is withdrawn, the patient may cough, swallow, or secretions may obscure the view. Even if a laryngeal view is achieved, it is likely to be too hurried to be of value. This technique is further limited by the need to withdraw the FB shortly after the examination. If an extraglottic device (EGD, e.g. , LMA) is inserted and the ETT is withdrawn, an FB can be passed through the EGD. This technique is compatible with either controlled or spon­ taneous ventilation, and it keeps extraglottic secretions from

•

•

•

obscuring the view. It allows regulation of the Fi0 and can 2 facilitate reintubation should it be required. This technique does require a properly seated EGD and is hazardous if the airway is significantly compromised. An Endotracheal Tube Introducer (ETTI, Portex Limited, Hyrhe, UK) , METTRO Mizus airway obturator (Cook Critical Care, Bloomington, IN) , or Eschmann Tracheal Introducer (i.e., bougie) can be introduced into the ETT. When the latter is withdrawn, the introducer can serve as a guide over which the ETT can be reintroduced if neces­ sary. As in the case of intubating over an FB, ETT passage over one of the devices mentioned above is not without chal­ lenges. Because these devices are solid, they cannot be used to insuffiate oxygen or provide ventilation. A hollow tube exchanger can be introduced permitting air­ way access, a means of oxygen administration, and serving as an airway "stylet" should this prove necessary. Considerations regarding oxygen insuffiation and jet ventilation will be dis­ cussed below. If DL has or is likely to fail, reintubation using an alterna­ tive indirect technique such as video-laryngoscopy may be extremely helpful. This can be done in conjunction with a tube exchanger.31 Mort found that 47/ 5 1 (92%) of recently extubated patients with a difficult airway were successfully reintubated over a tube exchanger, 87% on the first attempt; this contrasts with a first-pass success rate using DL of 1 4% in patients requiring reintubation in whom the tube exchanger had already been removed. Oxygen saturations below 90% and 80%, the incidence ofHR < 40 accompanied by hypoten­ sion, multiple attempts, and esophageal intubation were also significantly higher in the group without tube exchangers. 23

DEVICES TO ASS IST EXTUBATION • What Types of Hol low Tube Exchangers

Are Avai lable?

There are several commercial tube exchangers including the Cook Airway Exchange Catheter (C-AEC, Cook Critical Care), the Endotracheal Ventilation Catheter* (ETVC, Cardiomed International), the Staged Extubation Set (Cook Critical Care), the Arndt Airway Exchange Catheter Set (Cook Critical Care) , and the Sheridan Tracheal Tube Exchanger (Hudson Respiratory Care) . The Staged Extubation Set and Arndt Airway Exchange Catheter leave Amplatz guidewires rather than hollow tube exchangers in the airway. In addition to aiding tube passage, the hollow devices can be used to insuffiate oxygen or ventilate should it become necessary. Devices with a secure proximal con­ nection and multiple distal end holes are preferred (C-AEC and ETVC) . In contrast, the ETTI and the METTRO Mizus airway obturator are solid and cannot serve as an oxygen conduit. All of these devices are introduced through the existing ETT (or in the case of the Arndt device, through the working channel of a flexible *The author was a consultant to Cook in the development of the C-AEC and the inventor of the ETVC (Cardiomed International) . He receives no royalties or consultancy fees from either of these companies.

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endoscope) , and the distance markings on the tube exchanger are aligned with those on the ETT to ensure the distal tip of the tube exchanger is located proximal to the carina. The tube exchanger or guidewire remains in the airway after the ETT is withdrawn. • How Long a Duration Should a Tube

Exchanger Remain in the Ai rway?

If reintubation is anticipated, one should use a tube exchanger with the outer diameter (OD) that closely matches the inter­ nal diameter (ID) of the ETT. However, smaller diameter tube exchangers are generally better tolerated.2 3 Although guidewires are presumed to be more comfortable than exchange catheters, to date this has not been tested. Most patients tolerate the tube exchanger surprisingly well. With a properly positioned and well secured tube exchanger, it is generally possible for patients to speak, swallow, and cough with the device in situ.3 2 Although most often used orally, tube exchangers are more easily secured (and better tolerated) when inserted nasally. It is this author's experience that the longer the patient had been intubated, the more tolerant they are of the tube exchanger. If the patient has been intubated for several hours, coughing may indicate that the distal tip of the tube exchanger is near or beyond the carina. The distance marking should be checked and a chest x-ray performed to confirm correct placement. If the patient remains intolerant of the tube exchanger despite proper place­ ment, it may be appropriate to remove the device, although the need for reintubation may not declare itself for several hours. 23 As patients with known or suspected difficult airways are more likely to be successfully reintubated with fewer complications if performed over a tube exchanger, 2 3 a more cautious approach would be to promote tolerance by instilling topical anesthesia through the tube exchanger. A specific or arbitrary time period to leave a tube exchanger in situ is not rational. It is this author's practice to leave the device in place until the concern about the airway is resolved. Any patient requiring a tube exchanger would require the vigilance and expertise of a post anesthetic care unit (PACU) , ICU, or ED. It is essential that all those involved in the care of the patient appreciate that the tube exchanger is not a feeding tube. • How Is a Tube Exchanger Used to Support

Oxygenation or Ventilation?

There have been reports of patients suffering disastrous out­ comes when tube exchangers were used to deliver oxygen. This may be a consequence of misusing the device.33 However there is a report of a tube exchanger being used with low-flow oxygen insuffiation that nonetheless produced fatal barotrauma.34 An explanation of how this occurred is lacking but Duggan et al. advocated the administration of oxygen by face mask, cautioning against the use tube exchangers for this purpose. Generally, such advice seems prudent, however if the facemask oxygenation or ventilation proves inadequate and oxygen saturation falls during efforts to reintubate, this author would recommend low-flow oxygen insuffiation or cautious jet ventilation. Alternatively, a Bousiggnac CPAP valve (VYGON, Lansdale, PA) can be used with a tube exchanger to improve oxygenation.35 If face-mask oxygen supplementation, CPAP administra­ tion, or low-flow oxygen insuffiation ( 1 -2 LPM) fails to correct

hypoxemia, reintubation may be necessary. Low-flow oxygen insuffiation can continue, if deemed necessary, even while intu­ bation is being attempted. If reintubation is delayed or pro­ longed and hypoxemia is persistent or worsening in spite of oxygen insuffiation, jet ventilation should be considered. To avoid the morbidity associated with jet ventilation, the follow­ ing points should be addressed: •

•

•

•

•

•

•

•

•

Confirm that the distal tip of the tube exchanger is appro­ priately positioned above the carina, since jet ventilation into the bronchus or oropharynx can produce barotrauma. Delegate an assistant to hold the tube exchanger close to the lips or nose to ensure that the device does not get ejected during ventilation. Administer a muscle relaxant with appropriate sedation (if tolerated) to ensure vocal cord relaxation and facilitate both laryngoscopy and jet ventilation. This will lessen the risks of barotrauma. Attach the tube exchanger to the jet ventilator by means of a Luer-Lok adapter (the C-AEC, ETVC, and Sheridan JETTX have these) . Using a pressure-reducing valve, select the lowest driving pressure that results in chest expansion. "Wall pressure" of 50 psi is equivalent to 3500 em H 0 and can produce dramatic, 2 life-threatening barotrauma very quickly.33·34•36 Correct hypoxemia-this should be the primary objective. One breath causing adequate chest expansion may correct hypoxemia even though it may take a short while for this to become apparent. To avoid "breath stacking," the chest must be carefully observed. Subsequent breaths should not be delivered until it is clear that the chest has recoiled to a "resting volume." Facilitate exhalation by minimizing airway obstruction (vocal cord relaxation, optimal positioning, tongue displacement, suctioning, etc.) . 36 Jet ventilation may prove lifesaving, but it requires fastidious attention to detail to ensure that life-threatening complications do not develop.37 This should be performed by an experienced practitioner, ideally someone who is dedicated to the task of ventilation while the airway is managed by someone else.

AI RWAY EDEMA • What Factors Lead to Airway Edema?

Airway edema is not restricted to the vocal folds. In children sub­ glottic swelling is the greatest concern, whereas in adults glottic and supraglottic edema are the focus of concern. Patients may have airway swelling due to prone or Trendelenburg positioning, allergic or hereditary angioedema, thermal injuries, superior vena cava syndrome, or generalized swelling as in anaphylaxis, anasarca, and massive volume overload. They may have sustained injury to their tongue, uvula, or epiglottis during tracheal intubation or as a result of subsequent trauma, such as suctioning or seizures. Insertion of a round tube through a triangular glottis results in contact and pressure at the posteromedial aspect of the larynx.30 Inj ury can occur very early but this is usually of little consequence. Excessive or prolonged pressure can result in arytenoid perichondritis or chondritis, which heals poorly.

M a n a g e m e nt of Extu bation of a Patient Fo l l ow i n g a Pro l o n g ed Period of Mec h a n ica l Ve ntilation

Healing may result in fibrosis, producing subacute or chronic laryngeal or tracheal stenosis or an exuberant growth of granu­ lation tissue. Early post-extubation obstruction is likely to be a consequence of edema, bleeding, and occasionally granulation tissue or arytenoid dislocation. Much has been written about the duration of intubation and resultant airway injuries. However, the association between duration and incidence of airway injuries remains controversial. Most would maintain that the longer the duration of intuba­ tion, the greater the likelihood of airway edema. Significant airway injury may, however, occur early as a result of inadequate ETT securement, persistent attempts to phonate or cough, gastroesophageal reflux, larger diameter ETT, excessive cuff inflation pressure, traumatic laryngoscopy or intubation, and vocal fold granulomas. Some authorities recommend laryngos­ copy at approximately day 7 under general anesthesia, using telescopes and image magnification to assess the severity of injury. Only then can a judgment be made regarding the fea­ sibility of extubation, prolonging translaryngeal intubation, or the need for a tracheotomy.38 • What Techniq ues Are Usefu l to Assess

Airway Edema?

We have discussed the limited value of DL with the ETT in situ in contrast to extubation under general anesthesia with DL and image magnification. An alternative approach consists of controlled visualization using a flexible bronchoscope through an EGD. DL with image magnification provides the best ana­ tomical evaluation; the EGD/FB examination with spontane­ ous ventilation provides a good assessment of both form and function. This is achieved by substituting an EGD for the ETT. If tissue swelling is sufficiently severe, it may encroach on the ETT at any point along the length of the ETT. Prior to extubation, a "cuff-leak test" can be used to assess this. The oro­ pharynx is suctioned and the cuff is slowly deflated. The patient is asked to inhale and exhale slowly as the ETT is occluded. 39 An audible leak indicates the flow of air around the ETT. This has been found to be a useful predictor of successful extubation in pediatric trauma and burn victims as well as children with croup40 and was sensitive but not specific in predicting post­ extubation stridor and the need for reintubation in adultsY The cuff-leak test can be enhanced by quantifYing the leak during controlled ventilation. Lower cuff-leak volumes are pre­ dictive of post-extubation stridor, a need for reintubation, or both.42,43 Engoren did not find this to be predictive in postop­ erative cardiothoracic surgical patients44 although others have suggested that the cuff leak, expressed as a proportion of the delivered tidal volume, may have greater utility.45-47 Recently, ultrasonography has been proposed as a method of predicting laryngeal edema48 but others have found it no more sensitive than a cuff-leak test.49 • Are There Methods of Red ucing

Airway Edema?

It is unlikely that laryngeal edema can be eliminated but it may be possible to reduce it by intubating atraumatically under visual guidance when possible, selecting appropriately sized ETTs,

inflating the cuff with no more air than is required to achieve a seal, minimizing tube movement with proper securement and ETT support, head-up positioning when possible and possibly the prophylactic administration of corticosteroids. The benefits of steroids in preventing post-extubation stridor have been variable and probably depend on the patients selected, the specific ste­ roid, the doses and the timing of initial and subsequent doses. 5°53 If the patient manifests signs or symptoms suggestive of airway obstruction, laryngospasm and upper airway obstruction should be considered. If these are excluded, epinephrine (5 mL of 1 : 1 000 solution) by inhalation often results in rapid improvement of airway edema by means of temporary local vasoconstriction. Epinephrine can be administered as tolerated, although caution must be exercised in patients with hypertension, tachycardia, or conditions in which these are poorly tolerated. Rebound vasodi­ lation can also occur. Additional management measures might include fluid restriction or diuretic therapy. Helium is less dense than nitrogen and can be used, in lieu of nitrogen as a transport medium for oxygen when turbulent airflow is present. This mixture consists of a blend of oxygen and helium, typically 30:70, although the oxygen concentration can be enriched if required. The benefits are proportional to the concentration of helium and the extent to which turbulent flow is present. Helium-oxygen (Heliox) can be used concurrently with head elevation, corticosteroids, and epinephrine. The benefits from Heliox and epinephrine should be apparent within minutes. Deteriorating conditions should prompt reintubation.

TECH N I Q U E OF REI NTU BATION • How Should Reintu bation Over a Tu be

Exchanger Proceed?

If conservative measures are ineffective and reintubation over a tube exchanger is required, the tube exchanger can serve as a "jet stylet.''54 Denitrogenation should be optimized progress­ ing from face mask to CPAP resorting to insuffiation and jet ventilation as the situation dictates (see discussion above) . Depending on the design of the device, the proximal connector can be removed to permit the loading of a replacement ETT. If the fit is tight, a water-soluble lubricant can be applied to the tube exchanger, although care must be taken to ensure that this does not interfere with its handling. The tube exchanger must be long enough to ensure that the part protruding from the patient's mouth or nose is at least as long as the replacement ETT. If necessary, the ETT can be shortened. In general, the smaller the size difference between the outer diameter of the tube exchanger and the internal diameter of the replacement ETT, the easier reintubation is likely to be. The tube exchanger is held securely at the mouth or nose. The ETT is then passed over the exchanger. Throughout the procedure, the clinical con­ dition of the patient should be monitored and any additional medications to provide sedation, hemodynamic control, topical anesthesia, or neuromuscular blockade should be administered. The team should review the primary and contingency plans in advance. It may be prudent to request additional help or equip­ ment. If oxygenation can be sufficiently maintained, there is no urgency.

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A laryngoscope can be used to elevate the tongue and epiglot­ tis to facilitate advancement of the ETT over the tube exchanger. Even more effective-particularly in the patient in whom DL is likely or known to be difficult-is the use of an indirect or video­ laryngoscope to facilitate the tube exchange.31 This may permit laryngeal evaluation and visualized replacement of the ETT. If glottic visualization cannot be achieved, the ETT is advanced over the tube exchanger as it might be over an FB, with tongue retraction or a jaw thrust. If resistance is encoun­ tered at the presumed depth of the glottic inlet, the ETT should be rotated counterclockwise, but force should never be applied. If the patient is still breathing spontaneously, the airway prac­ titioner should wait for an inspiratory effort and advance the ETT as the vocal folds abduct. Frequently, the tube exchanger is inadvertently advanced while the ETT is being introduced. If the ETT has passed easily, the tube exchanger can be removed (or a capnograph can be attached to the tube exchanger prior to its removal) , whereupon intra-tracheal placement of the ETT should be verified by capnography and auscultation. • What if Reintu bation Over the Tu be

Exchanger Fails?

If reintubation over the tube exchanger fails, several options exist. The adequacy of oxygenation by bag-mask or jet ventila­ tion with the tube exchanger in situ should be assessed: •

•

•

Oxygenation is adequate: Time and expertise may permit the use of an alternative device, such as a flexible bronchoscope or a video-laryngoscope. (These devices might also be considered prior to the removal of the ETT, along with the tube exchanger.) It is preferable to leave the tube exchanger in place, if possible, during the reintubation attempt. Alternatively, an Aintree cath­ eter (see Figure 12. 1 in Chapter 1 2) can be inserted over the small (pediatric) tube exchanger to reduce the space between the OD of the tube exchanger and the ID of the ETT.55 Oxygenation or ventilation is inadequate: If possible, confirm using a capnograph (or video-laryngoscope) that the tube exchanger is still in the trachea. If jet ventilation is avail­ able, it can be used if required but prior to delivery of the first breath, an assessment should be made to ensure that the device has not become displaced. An assistant should listen over the epigastrium to ensure the absence of air entry dur­ ing ventilation. If this is successful, the next breath should ensure that the left lung is also ventilated, reducing the risk of barotrauma from endobronchial jet ventilation. If venti­ lation restores oxygenation, alternative plans can be put in place in a calm and efficient manner. Jet ventilation should be provided only insofar as it is required to achieve a non­ threatening oxygen saturation. If intubation over the tube exchanger was not successful, prior to its removal, reconsider the following: o was a laryngoscope used to provide adequate tongue retraction? o was a video-laryngoscope used in conjunction with (or without) the tube exchanger? o if a video laryngoscope was not used or was unsuccessful, could the exchange be viewed with a flexible bronchoscope? o might the use of a smaller size ETT be possible?

was an Aintree Catheter used together with the pediatric tube exchanger? o an ETT with a curved bevel (e.g., Parker Medical Inc., Bridgewater, CT) reduces the gap between the tube exchanger and ETT and may facilitate reintubation If tongue retraction, a smaller size ETT, and a flexible or video-laryngoscope fail to facilitate reintubation and jet ven­ tilation is not immediately available, assess the feasibility of bag-mask-ventilation (BMV) with the tube exchanger in situ. If this cannot be accomplished, the tube exchanger may be removed and further attempts made to achieve BMV If BMV cannot be achieved, consider placement of an EGD. If ventilation and oxygenation still cannot be achieved, the practitioner should refer to the Failed Airway (can't intubate, can't oxygenated) Algorithm (see section "The Failed Airway Algorithm" in Chapter 2) . Time is critical and if adequate oxygenation cannot be achieved quickly, a surgical airway is mandatory. o

•

•

•

• How Should ETT Exchange of an I ntubated

Patient with a Difficult Airway Proceed Without a Tu be Exchanger?

If a patient with a difficult airway requires replacement of an existing ETT and a tube exchanger is not available, an FB loaded with an ETT can be introduced alongside the existing ETT. The pharynx should be carefully suctioned. If the exist­ ing ETT still has an intact cuff, it can be deflated to allow FB passage alongside. Once tracheal access by the FB has been con­ firmed by visualizing tracheal rings and carina, the original tube can be withdrawn and the new ETT advanced over the FB. DL requires a line-of-sight from the practitioner to the larynx. Indirect laryngoscopy includes those techniques that have no such requirement. This can be achieved with opti­ cal, video, or fiberoptic technology and enables the viewing of glottis that may be difficult to see directly (see Chapter 1 1 ) . For the patient requiring reintubation in whom DL had previously been difficult, indirect laryngoscopy is particu­ larly useful. 3 1

TRAC H EAL EXTUBATION The trachea of the patient described at the beginning of this chapter was intubated using DL with an ETTI. The ETTI was placed blindly and successful placement cannot be guar­ anteed. In a prospective study involving 1 1 ,257 adults, intuba­ tion by DL alone could not be accomplished in 1 00 patients. Nonvisualized intubation with an ETTI was successful in 80/89 cases; out of the successful intubations 50% required more than one attempt.56 Though the authors regarded this as a validation of the ETTI strategy, the fact remains that it failed 1 0% of the time and required multiple attempts (after multiple attempts) in half the patients.

Laryngoscopy that fails to reveal the larynx is a "jailed laryn­ goscopy" whether intubation succeeds or foils. Every extuba­ tion should include the realization that reintubation may become necessary. Higher-risk airways demand strategies that increase the likelihood of successful extubation and facilitate

M a n a g e m e nt of Extu bation of a Patient Fo l l ow i n g a Pro l o n g ed Period of Mec h a n ica l Ve ntilation

reintubation should it become necessary. Patients who are phys­ iologically challenged57 may further benefit from the ability to provide supplemental oxygen and/or ventilation during efforts to reestablish the airway. Performing direct or indirect (e.g., video) laryngoscopy may facilitate reintubation even when a tube exchanger is used. The patient in this case demonstrated criteria that are asso­ ciated with a successful wean from mechanical ventilation. However, such criteria are not synonymous with successful extubation. Demonstration of a large cuff leak reduces the like­ lihood of post-extubation stridor or a need for reintubation on account of airway obstruction. Examination of the vocal cords following extubation, by indirect laryngoscopy or FB through an EGO, may provide additional information. The oropharynx was suctioned, a cuffleak was demonstrated, a tube exchanger was inserted, aligning the distance markings with those of the ETT, the latter was withdrawn, and the tube exchanger was secured in the midline of the patient's mouth. The tube exchanger was well tolerated and left in place for 3 hours during which time the patient continued to improve. He was able to talk and clear his secretions. The tube exchanger was then removed. Had a cuff leak not been present, the options are less clear. A significant number of these patients would not require a tracheotomy. The patient can be taken to the operating room to have the glottis examined using DL and image magnifica­ tion under general anesthesia with paralytics. 29 An alternative approach would be to use intravenous anesthesia and a short­ acting muscle relaxant, followed by the insertion of an EGO and extubation. This approach should be used with caution, particularly in the patient with a difficult airway. It has regarded as an "advanced airway manoeuver" by the Difficult Airway Society and should only be considered if the practitioner has considerable experience with the EGD.5 Once placed, the EGO cuff is inflated, and its position would be optimized using an FB. The neuromuscular blocker is reversed, and spontaneous ventilation is resumed. After extubation, flexible endoscopy through the lumen of the EGO is used to assess the glottic appearance and function, while the adequacy of spontaneous ventilation is assessed. Three outcomes might result: •

•

•

The assessment is unfavorable-reintubation can be achieved over the FB (with or without an Aintree catheter [Cook Critical Care] depending on the type of EGO used) . If rein­ tubation is then performed in this patient, a tracheotomy is probably indicated. This can be done at the bedside using one of several techniques, including percutaneous dilata­ tional tracheotomy. The examination is favorable-sedation is discontinued and the EGO is removed when appropriate. There remains the possibility that reintubation will subsequently be required; however, the anatomy and glottic function have been assessed, and the patient has undergone a trial of extubation. The examination is indeterminate-a tube exchanger or if an Staged Extubation Set (Cook Critical Care) is used, an Amplatz guidewire can be introduced and left in situ until the clinical status of the glottis becomes clear.

S U M MARY The risk associated with tracheal extubation (or tube exchange) may be understood along a risk continuum from low to very high risk. This entails rwo dimensions: the probability that extu­ bation will succeed and the difficulty of managing the airway should it fail. An attempt to manage a failing airway is inher­ ently more complex than an attempt made under controlled conditions. The complications associated with prolonged or multiple attempts in a physiologically challenged patient are serious. Preemptive strategies should include consideration of the risks and an articulated strategy to deal with contingen­ cies as described that maximize the probability of extubation succeeding and reintubation, if required, being successful. This includes consideration of the use of a tube exchanger to provide continuous access to the airway and enabling oxygenation and/ or ventilation should this be required.

REFERENCES 1. Peterson GN, Domino KB, Caplan RA, Posner KL, Lee LA, Cheney FW Management of the difficult airway: a closed claims analysis. Anesthesiology. 2005; 1 03:33-39. 2. Asai T, Koga K, Vaughan RS . Respiratory complications associated with tracheal intubation and extubation. Br J Anaesth. 1 998;80:767-775. 3 . Cook TM, Woodall N, Harper J, Benger ] . Major complications of airway management in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society. Part 2: intensive care and emergency departments. Br J Anaesth. 20 1 1 ; 1 06:632-642. 4. Cook TM, Woodall N, Frerk C. Major complications of airway manage­ ment in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society. Part 1 : anaesthe­ sia. Br J Anaesth. 20 I I ; I 06:6 1 7-63 1 . 5 . Popat M , Mitchell V, Dravid R, Patel A, Swampillai C, Higgs A. Difficult airway society guidelines for the management of tracheal extubation. Anaesthesia. 20 1 2;67:3 1 8-340. 6. Cavallone LF, Vannucci A. Review article: extubation of the difficult airway and extubation failure. Anesth Analg. 20 1 3 ; 1 1 6:368-383. 7. Cooper RM , Khan SM. Extubation and reintubation of the difficult airway. In: Hagberg C., ed. Benumof and Hagberg's Airway Management. 3rd ed. Philadelphia, PA: Elsevier-Saunders; 2 0 1 2 : 1 0 1 8- 1 046. 8 . Apfelbaum JL, Hagberg CA, Caplan RA, et al. Practice guidelines for man­ agement of the difficult airway: an updated report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology. 20 1 3 ; 1 1 8:25 1 -270. 9. Law JA, Broemling N, Cooper RM , et al. The difficult airway with rec­ ommendations for management-part 2-the anticipated difficult airway. Can ] Anaesth. 20 1 3;60: 1 1 1 9- 1 1 38 . 1 0 . Shiga T, Wajima Z, Inoue T, Sakamoto A. Predicting difficult intubation in apparently normal patients: a meta-analysis of bedside screening test performance. Anesthesiology. 2005; I 03:429-437. 1 1 . Norskov AK, Rosenstock CV, Wetterslev J, Astrup G, Afshari A, Lundstrom LH. Diagnostic accuracy of anaesthesiologists' prediction of difficult air­ way management in daily clinical practice: a cohort study of 1 8 8,064 patients registered in the Danish Anaesthesia Database. Anaesthesia. 20 1 5 ;70:272-28 1 . 1 2 . Hill RS, Koltai PJ, Parnes SM. Airway complications from laryngoscopy and panendoscopy. Ann Otol Rhino! Laryngol. 1 987;96:6 9 1 -694. 1 3 . Rose OK, Cohen MM, Wigglesworth OF, DeBoer DP. Critical respira­ tory events in the postanesthesia care unit. Patient, surgical, and anesthetic factors. Anesthesiology. 1 994;8 1 :4 1 0-4 1 8 . 1 4 . Mathew J P, Rosenbaum S H , O'Connor T, Barash P G . Emergency tra­ cheal intubation in the postanesthesia care unit: physician error or patient disease? Anesth Analg. 1 990;7 1 :69 1 -697. 1 5 . Lee PJ, MacLennan A, Naughton NN, O'Reilly M . An analysis of reintu­ bations from a quality assurance database of 1 52,000 cases. J Clin Anesth. 2003; 1 5 : 575-5 8 1 . 1 6 . Chinachoti T, Chau-in W, Suraseranivongse S , Kitsampanwong W, Kongrit P. Postoperative reintubation after planned extubation in Thai

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17.

18.

19. 20. 21.

22. 23. 24.

25.

26. 27.

28. 29.

30. 31. 32. 33.

34.

35.

36.

37. 38.

39. 40.

41. 42. 43. 44. 45.

Anesthesia Incidents Study (THAI Study) . } MedAssoc Thai. 2005;88 (suppl 7) :S84-S94. Ting PC, Chou AH, Yang MW, Ho AC, Chang CJ, Chang SC. Postoperative reintubation after planned extubation: a review of 1 37,866 general anesthetics from 2005 to 2007 in a Medical Center ofTaiwan. Acta Anaesthesia! Taiwan. 20 1 0;48: 1 67- 1 7 1 . Emery SE, Smith MD, Bohlman H H . Upper-airway obstruction after multilevel cervical carpectomy for myelopathy. J Bone joint Surg Am. 1 99 1 ;73: 544-55 1 . Tyers MR, Cronin K: Airway obstruction following second operation for carotid endarterectomy. Anaesth Intensive Care. 1 986; 14:3 1 4-3 1 6 . Levelle JP, Martinez OA. Airway obstruction after bilateral carotid endar­ terectomy. Anesthesiology. 1 985 ;63 :220-222. Venna RP, Rowbottom JR. A nine year retrospective review of post opera­ tive airway related problems in patients following multilevel anterior cervi­ cal carpectomy. Anesthesiology. 2002;9 5 :A 1 1 7 1 . Lacoste L , Gineste D , Karayan ] , e t al. Airway complications i n thyroid surgery. Ann Otol Rhino! Laryngol. 1 993; 1 02:44 1 -446. Mort TC. Continuous airway access for the difficult extubation: the effi­ cacy of the airway exchange catheter. Anesth Analg. 2007; I 0 5 : 1 357-1 362. Gandia F, Blanco ]. Evaluation of indexes predicting the outcome of venti­ lator weaning and value of adding supplemental inspiratory load. Intensive Care Med. 1 992; 1 8 :327-333. Demling RH, Read T, Lind LJ, Flanagan HL. Incidence and morbidity of extubation failure in surgical intensive care patients. Crit Care Med. 1 988; 1 6: 573-577. Mort TC: Emergency tracheal intubation: complications associated with repeated laryngoscopic attempts. Anesth Analg. 2004;99:607-6 1 3 . Sakles J C , Chiu S, Mosier ], Walker C, Stolz U , Reardon RF. Th e impor­ tance of first pass success when performing orotracheal intubation in the emergency department. Acad Emerg Med. 20 1 3;20:7 1 -78. Ford RW. Confirming tracheal intubation-a simple manoeuvre. Can Anaesth Soc]. 1 983;30: 1 9 1 - 1 93 . Benjamin B, Cummings CW, Fredrickson J M , et al. Laryngeal trauma from intubation: endoscopic evaluation and classification. Otolaryngology: Head and Neck Surgery. St. Louis, MO: Mosby-Year Book, Inc.; 1 998:20 1 8-2033. Benjamin BF, Holinger LM. Laryngeal complications of endotracheal intubation. Ann Otol Rhino! Laryngol. 2008; 1 1 7:2. Mort TC. Tracheal tube exchange: feasibility of continuous glottic viewing with advanced laryngoscopy assistance. Anesth Analg. 2009; I 08: 1 228- 1 23 1 . Cooper RM . Th e use o f an endotracheal ventilation catheter in the man­ agement of difficult extubations. Can J Anaesth. 1 996;43:90-93. Ruxton LM. Fatal accident inquiry into the death of Gordon Ewing. Available at: https://www.scotcourts.gov.uk/search-judgments/judgment?id= 328e86a6-8980-69d2-b500-ffilOOOd74aa7. Duggan LV, Law JA, Murphy MF. Brief review: supplementing oxygen through an airway exchange catheter: efficacy, complications, and recom­ mendations. Can J Anaesth. 20 I I ; 5 8 : 5 60-568. Lee C, Cooper RM , Goldstein D. Management of a patient with trachea­ malacia and supraglottic obstruction after thyroid surgery. Can J Anaesth. 20 1 1 ; 5 8 : 1 029-1 033. Cooper RM , Cohen DR. The use of an endotracheal ventilation cath­ eter for j et ventilation during a difficult intubation. Can } Anaesth. 1 994;4 1 : 1 1 96-1 1 99. Benumof JL. Airway exchange catheters: simple concept, potentially great danger. Anesthesiology. 1 999; 9 1 : 342-344. Benjamin B. Prolonged intubation injuries of the larynx: endoscopic diagnosis, classification, and treatment. Ann Otol Rhino! Laryngol. 1 993; 1 60 (suppl) : 1 - 1 5 . Adderley RJ, Mullins GC. When t o extubate the croup patient: the "leak" test. Can } Anaesth. 1 987;34:304-306. Kemper KJ, lzenberg S, Marvin JA, Heimbach DM. Treatment of postex­ tubation stridor in a pediatric patient with burns: the role of heliox. } Burn Care Rehabil. 1 990; 1 1 :337-339. Fisher MM, Raper RF. The 'cuff-leak' test for extubation. Anaesthesia. 1 992;47: 1 0 - 1 2 . Miller RL , Cole R P. Association between reduced cuff leak volume and postextubation stridor. Chest. 1 996; 1 1 0 : 1 03 5 - 1 040. Efferen LS, Elsakr A: Post-extubation stridor: risk factors and outcome. J Assoc Acad Minor Phys. 1 998;9:65-68. Engoren M. Evaluation of the cuff-leak test in a cardiac surgery popula­ tion. Chest. 1 999; 1 1 6 : 1 029- 1 03 1 . Jaber S , Chanques G , Matecki S , et al. Post-extubation stridor in intensive care unit patients. Risk factors evaluation and importance of the cuff-leak test. Intensive Care Med. 2003;29: 69-74.

46. De Bast Y, De Backer D, Moraine JJ, Lemaire M, Vandenborght C, Vincent JL. The cuff leak test to predict failure of tracheal extubation for laryngeal edema. Intensive Care Med. 2002;28 : 1 267- 1 272. 47. Sandhu RS, Pasquale MD, Miller K, Wasser TE. Measurement of endotra­ cheal tube cuff leak to predict postextubation stridor and need for reintu­ bation. j Am Col! Surg. 2000; 1 90:682-687. 48. Sutherasan Y, Theerawit P, Hongphanut T, Kiatboonsri C, Kiatboonsri S. Predicting laryngeal edema in intubated patients by portable intensive care unit ultrasound. } Crit Care. 2 0 1 3;28:675-680. 49. Mikaeili H, Yazdchi M, Tarzamni MK, Ansarin K, Ghasemzadeh M: Laryngeal ultrasonography versus cuff leak test in predicting postextuba­ tion stridor. ] Cardiovasc Thorac Res. 20 1 4;6:25-28. 50. Shemie S . Steroids for anything that swells: dexamethasone and postextu­ bation airway obstruction. Crit Care Med. 1 996;24: 1 6 1 3- 1 6 1 4. 5 1 . Roberts RJ, Welch SM, Devlin JW. Corticosteroids for prevention of postextubation laryngeal edema in adults. Ann Pharmacother. 2008;42: 686-69 1 . 52. Cheng K, Chen C , C K T, Chen H , Lu C , Zhang H . Methylprednisolone reduces the rates of postextubation stridor and reintubation assoiated with attenuated cytokine responses in critically ill patients. Minerva Anestesiol. 2 0 1 1 ;77: 503-509. 53. Khemani RG, Randolph A, Markovitz B. Corticosteroids for the preven­ tion and treatment of post-extubation stridor in neonates, children and adults. Cochrane Database Syst Rev. 2009: Cd00 1 000. 54. Bedger RC]r, Chang JL. A j et-stylet endotracheal catheter for difficult air­ way management. Anesthesiology. 1 987;66:22 1 -223. 5 5 . Law ], Duggan L. Extubation guidelines: use of airway exchange catheters. Anaesthesia. 20 1 2;67: 9 1 8-9 1 9. 56. Combes X, Le Raux B, Suen P, et al. Unanticipated difficult airway in anesthetized patients: prospective validation of a management algorithm. Anesthesiology. 2004; I 00: 1 1 46- 1 1 50. 57. Mosier J, Joshi R, Hypes C, Pacheco G, Valenzuela T, Sakles J. The physi­ ologically difficult airway. West J Emerg Med. 20 1 5 ; 1 6: I I 09- 1 1 1 7.

SELF - EVALUATION QU ESTIONS 30. 1 . Which o f the following i s a reliable method i n assessing airway edema? A. direct or indirect laryngoscopy prior to extubation B. ultrasonic evaluation of the vocal cords C. performing a "cuff-leak test" D. presence of facial edema E. none of the above 30.2. Which of the following are useful steps to minimize the morbidity associated with jet ventilation through a hol­ low tube exchanger? A. ensure that the tip of tube exchanger above the carina

IS

positioned

B. avoidance of "breath stacking" C. use the lowest driving pressure that results expansion

m

chest

D. ensure adequate muscle relaxation E. all of the above 30.3. Which of the following may be helpful to reduce airway edema? A. elevation of the head of the bed B. the use of nebulized epinephrine C. fluid restriction D. the use of diuretic therapy E. all of the above

377

C H A PT E R 3 1

Airway Manage ment of a Patient in a Ha lo-Jac ket with Acute O bstruction of a Reinforced Trachea l Tube Dietrich Henzler

CAS E PRESE NTATION

377

PAT I E NT CO N S I D E RATI O N S . . . . . . . . . . . . . . . . . . . . .

378

P LAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 379 P ROC E D U R E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

381

S U M MARY . . .

382

SELF-EVALUATIO N Q U ESTI O N S . . . . . . . . . . . . . . . . . . . 382

CASE PRESENTATION A 52-year-old worker of normal body habitus was injured in a fall from approximately 1 5 feet (5 m) of height. He sustained fractures to the vertebral bodies of C3 and C4, as well as a C5 transverse process fracture. He was retrieved by an ambu­ lance team and admitted to the hospital in a hemodynamically stable condition. His breathing on admission was noted to be "normal," albeit with decreased air entry to the right side. An infiltrate on chest x-ray was consistent with aspiration. Neurologically, the patient was awake and alert. He had evi­ dence of a Brown-Sequard syndrome with an almost complete paralysis of his left limbs and a sensory deficit on his right. The patient's neck had been placed in a rigid cervical collar at the scene and he was given oxygen via a face mask. Tracheal intubation was performed uneventfully by awake flexible bron­ choscopic intubation in the operating room (OR) for dorsal fixation of his C-spine. Completion of internal fixation by ven­ tral stabilization was planned at a later date and in the interim the patient was placed in a halo frame for external fixation

(Figure 3 1 - 1 ) . He was then transferred to the intensive care unit (ICU) intubated and ventilated, as his oxygen require­ ments had increased to 60%. An aspiration pneumonia was suspected and he was sedated and ventilated according to a lung protective ventilation strategy. Past medical history included hypertension, gastroesopha­ geal reflux disease (GERD), and a question of significant alco­ hol consumption. By day 3 of his ICU admission, the pulmonary situation had improved marginally. He still required an Fi0 of 0.45 and was 2 breathing spontaneously with pressure support of 1 2 em H 0 2 and positive end-expiratory pressure (PEEP) of 1 0 em H 0. 2 Attempts to wean the pressure support had failed at that point, resulting in tachypnea and oxygen desaturation. Thick purulent sputum was being suctioned from his endotracheal tube (ETT) twice per shift, and he was receiving empiric antibiotics to treat his presumed pneumonia. Agitation had become a major issue, thought to be delirium tremens secondary to alcohol withdrawal. A cranial CT had ruled out posttraumatic intracerebral hemorrhage as the under­ lying cause. The patient was difficult to manage, often requiring more than one nurse at the bedside, and he had tried to remove lines and ETT with his functioning hand. For this reason he required passive restraints and sedation. On day 4, the bedside nurse called urgently to report that the patient had bitten on the tube in severe agitation. To pre­ vent kinking of the tube during surgery, the patient had been intubated with a wire-reinforced (armored) ETT, and had unfortunately not undergone an exchange to a regular ETT prior to transfer to the I CU. The reinforced ETT was now flat­ tened at the level of the patient's teeth (Figure 3 1 -2) , causing acute obstruction by its significantly reduced inner diameter. The patient was being inadequately ventilated, with a decrease in minute ventilation and a drop of Sp0 to 87%, together 2 with hemodynamic decompensation.

378

Ai rway M a n a g e m e n t i n the I nte n s ive Ca re U n it (ICU)

The patient was not known to have coronary artery or cere­ brovascular disease; he had no specific risk factors and was thus unlikely to have hypoperfusion of vital organs. As such, a bor­ derline Sp0 could be tolerated for a short period of time. 2 On the other hand, acute obstruction of the artificial airway will lead to severe dyspnea and increased respiratory effort. The patient is forced to increase respiratory drive, thus generating more negative inspiratory pressure to maintain tidal volume. This can be quite dangerous for the risk of developing nega­ tive pressure pulmonary edema or post-obstructive pulmonary edema (POPE, see Chapter 6 1 ) . We can conclude that this patient needs urgent troubleshooting including an emergency ETT exchange to prevent further harm.

F I G U R E 3 1 - 1 . Patient w i t h h a l o fra me for sta b i l ization o f cervica l s p i n e fractu res.

F I G U R E 3 1 -2. Reinfo rced tube with a l m ost c o m p l ete o bstruction ca u sed by biti n g o n the m eta l a rm o red pa rt.

PATI ENT CON S I D E RATIONS • Medical Considerations I s the Patient at Acute Risk of S u ffe r i n g H a r m ?

Hemodynamics and gas exchange must b e included i n assessing the need for emergency treatment. While an Sp0 of 87% is 2 certainly abnormally low, it might not impose an acute danger to the patient in the short term. Two factors are important: whether the patient's organs are at risk of hypoperfusion (and thus cellular hypoxia) and if sufficient oxygen-carrying capacity exists to compensate for a lower oxygen saturation. Oxygen-carrying capacity (or oxygen delivery) depends on cardiac output, hemoglobin concentration, and hemoglobin oxygen saturation. The patient was slightly anemic (Hgb 1 1 0 g dL-1), although with an increase in heart rate from 8 1 to 1 05 beats-per minute following development of the tube obstruc­ tion, some compensation had occurred by increasing cardiac output to maintain oxygen delivery.

What Are t h e M a n a g e m ent Opti o n s fo r Th i s S ituati o n ?

I n a prospective multicenter study involving 426 ICU patients, Boulain1 reported that 57 episodes of self-extubation occurred in 46 patients ( I I %) and of these, 1 8 patients did not require reintubation after their first (or only) episode of self-extubation. Therefore, it is necessary to assess the patient's ability to breathe unassisted and determine the need for further ventilatory assis­ tance. While it is possible that a subgroup of self-extubated patients not yet capable of completely breathing on their own may be amenable to noninvasive ventilation (NIV) , this patient's halo frame precluded NIV due to technical constraints. Indicators for the ability to ventilate include respiratory rate, the patient's work ofbreathing, and gas exchange. In this patient, an increase in heart and respiratory rate and the decrease in Sp0 , combined with clearly visible usage of accessory muscles 2 of respiration indicated the need for further ventilatory sup­ port. His respiratory failure was likely multifactorial, including the aspiration pneumonia as well as compromised intercostal and diaphragmatic muscular function due to his high spinal cord injury. As the patient needed further ventilatory assistance, an ETT exchange was indicated.

• Ai rway Considerations What S h o u l d be the I n it i a l M a n a g e m e nt?

First, the patient should be placed on Fi0 of 1 .0 to improve 2 oxygenation. This increased the Sp0 to 9 1 o/o, which helped 2 to buy some time to adequately prepare for the tube exchange procedure. Second, the respiratory drive has to be reduced to decrease the risk of POPE. Therefore, sedation was increased and the patient received 1 0 mg of morphine IV The inspiratory pressure from the ventilator was increased to overcome airway resistance. To help with expiration and prevent dynamic hyper­ inflation, an artificial cuff leak was created by deflating the ETT cuff to the point of an audible leak during expiration. In this manner, some degree of minute ventilation was maintained, as not all of the delivered tidal volume escaped and the patient continued spontaneous breathing efforts. Alternative approaches in the case of life-threatening hypox­ emia should aim to temporarily restore oxygenation until a definitive airway can be placed. The existing ETT, if ineffec­ tive, can be removed and the patient's respiratory efforts assisted

Ai rway M a nagement of a Patient i n a H a l o-J a c ket with Acute Obstruction of a Reinfo rced Tra c h e a l Tu be

with bag-mask-ventilation. Ventilation can be improved by use of an oropharyngeal or nasopharyngeal airway, if tolerated. However, in most cases, even with a leaky cuff, some ventila­ tion can be maintained through an ETT by hyperventilating with high flows and respiratory rate (> 30 breaths per minute) , mimicking high-frequency ventilation. The high-frequency oscillation (HFO) mode of ventila­ tion can provide sufficient oxygenation even with a cuff leak. Indeed, during routine use of HFO, a cuff leak is sometimes purposefully used to improve ventilation. It is an ideal rescue maneuver in a situation where a patient's oxygen desaturates and cannot be ventilated by other means. This option could be considered before a leaky tube was removed. HFO would be the preferred technique in this situation if the patient had profound gas exchange impairment, such as AROS, to be used until arrangements for safe ETT exchange were made. There should always be alternatives at hand in case the first attempt to reintubate the patient fails following removal of the faulty ETT. These can follow the ASA algorithm for the diffi­ cult airway and might include, but are not confined to: smaller ETTs; alternatives to direct laryngoscopy (OL) ; an appropri­ ately sized EGO (ideally second generation, intubating type) ; flexible bronchoscope and cricothyrotomy equipment. More help should be obtained: a difficult situation such as this can always be better managed with additional experienced medical and nursing staff. Calling for additional expertise is not a sign of incompetence, but of professionalism! H ow M i g ht t h e P rese n ce of a H a l o J a c ket I m pact Ai rway M a n a g e m e nt?

The presence of a halo jacket can adversely impact all facets of airway management. In this case, tracheal intubation had initially been performed by a flexible bronchoscope awake in this patient, and the glottis view under OL had not been assessed thereafter. The halo jacket usually fixes the head in a neutral position, and prevents any flexion or extension of the neck (Figure 3 1 - 1 ) . With attempted OL, it is likely that at best a Cormack-Lehane grade 3 view will be achieved. Tracheal intubation is more likely to suc­ ceed with alternatives to OL, such as flexible or rigid fiber- or video-optic devices/ although these too can fail in this scenario (see Chapters 1 0 and 1 1 ) . Should intubation fail and the patient require oxygenation by positive pressure ventilation between attempts, BMV could also prove challenging due to limited head extension, and for the same reason, EGO insertion may be dif­ ficult. Finally, cricothyrotomy is usually performed with the head extended, so this can also be expected to be somewhat more dif­ ficult in the patient with a halo jacket. In this agitated and uncooperative patient, it is unlikely that application of topical airway anesthesia, light sedation, and "awake look'' assessment, for example, by video-laryngoscope (VL) will be an option; deeper sedation carries the risk of apnea. Alternative approaches must be considered. What Other R i s ks Are I n h e re n t in T h i s S ituati o n ?

Enteral nutrition imposes a n additional risk for aspiration while the airway is unprotected. Enteral feeds should be stopped immediately and the feeding tube suctioned to clear as much content as possible from the stomach.

An already agitated patient may well get more delirious if ventilatory support suddenly stops and hypoxemia devel­ ops. Sedation will also be needed to have the patient tolerate the tube exchange procedure. On the other hand, should reintubation fail during tube exchange, preservation of spontaneous ventilation will add a margin of safety. While non-pharmacological ways of calming the patient ("talk-down" and reassurance with the help of additional staff) would be helpful, it may not be practical for this patient. If needed, short-acting drugs such as propofol are preferred. The reasons for the patient's continuing need for mechanical ventilation are weakness and pneumonia. Weakness alone as a cause of respiratory failure could be treated by NIV However, in this case, severe agitation is a contraindication to NIV and as previously suggested, the halo jacket will cause difficulty with its application. Pneumonia on the other hand causes edema, atelectasis, and ventilation-perfusion mismatch, resulting in hypoxemic respiratory failure. To aggravate the situation, the loss of PEEP due to the cuff leak will lead to even more atel­ ectasis formation in unstable regions. Furthermore, functional residual capacity (FRC) will be reduced, increasing the patient's susceptibility to hypoxemia. As the combination of these fac­ tors increases the risk of rapidly developing hypoxemia, tube exchange should not be deferred for long, and when done, should be performed with attention to maintaining patient oxygenation during the process. Although a leak is clearly audible, other significant altera­ tions of the airway should be anticipated. Mucosal swelling from inflammation and general edema, as well as displacement of tissue from the previous trauma may cause physical impedi­ ment to the placement of a new ETT or total obscuring of laryngeal inlet anatomy after the defective tube is removed.

PLAN • What Is the Best Strategy to Secu re the

Airway and Avoid Compl ications?

In evaluating the different options one has to consider the following key points: •

•

•

•

How much time is there to act? What equipment is available? Which technical skills are available? For the tube change, should spontaneous ventilation be maintained or ablated?

The first question has already been answered: even though the patient is temporarily stable, he will not tolerate the present situation for a prolonged period of time. The necessary equip­ ment should be obtained immediately from a difficult airway cart, as well as additional expertise. In an ICU airway emer­ gency, the needed equipment is rarely available at the bedside. Contents and location of the airway equipment cart within the ICU should be well known. If necessary, additional equipment should be obtained from the OR. Which procedure to choose will depend partially on the skills and experience of the attending practitioner. While there is much to be said for using familiar techniques and equipment,

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if time permits, additional expertise can be obtained to perform a less familiar technique (e.g., tracheotomy) , if indicated. Preservation of spontaneous respiration during the tube change will provide the advantage of helping to maintain oxy­ genation for a short period of time should placement of the new ETT prove problematic after removal of the defective one. However, this patient is agitated and will likely have to be deeply sedated for the procedure, putting him at risk of apnea. The downside of an unconscious, apneic patient (i.e., having to manage gas exchange, airway patency, and airway protec­ tion) would then occur without the upside of conditions opti­ mized by a muscle relaxant. On the other hand, choosing to deliberately ablate spontaneous respirations with an induction dose of sedative/hypnotic and use of a neuromuscular blocking agent will provide for optimal conditions for the tube change but should occur only with an appreciation of (and prepara­ tions for) the difficulty that may be encountered during the procedure.

conditions will actually improve. On the other hand, BMV with a two-person technique would be easier without the halo, while the cervical spine was manually immobilized by another assistant. Removal of the halo would be appropriate only if all other options have failed and the patient was at risk of acute hypoxemic injury.5 To summarize the options: •

•

•

• What Options Exist for Exchanging the ETT?

As pointed out above, obstruction of the upper airway imposes a significant risk for the placement of a new ETT. With any procedure requiring complete removal of the ETT from the airway before placement of the new one, there is a chance that the new ETT might not be able to advance into the trachea.3 This could be caused by displacement, collapse, or swelling of tissue, which was previously held open by the ETT in situ. For the tube exchange, a few options exist. With appropri­ ate preparation, the defective ETT can simply be removed and a new one placed. For this option (as discussed in the section "How Might the Presence of a Halo Jacket Impact Airway Management?" in this chapter) , it must be appreciated that intubation by DL will most likely not succeed. Other options such as the lightwand or VL such as the GlideScope are more likely to succeed/ but (a) the equipment must be available and (b) the practitioner must be experienced in its use. Use of an airway exchange catheter would be judged preferable in many situations, however, in this case, the exchanger catheter may not pass through the stenotic area of the ETT. If an experienced surgeon is immediately available, a surgical airway (cricothy­ rotomy or tracheotomy) will result in an almost 1 OOo/o success rate, although it is the most invasive option. The complication rate, including risk of significant bleeding, false cannula passage, pneumothorax, and infection, has been reported to be as high as 1 2 . 5 % in elective tracheotomy4 and even higher in emergen­ cies. However, surgical airway in this setting would help avoid the risks inherent in a difficult tube change, and might be con­ sidered if time permits and there is a high probability that the patient will go on to tracheotomy anyway in the coming days or weeks. Otherwise, it will be a fallback option should other procedures fail for technical or time-critical reasons. Finally, in a desperate situation, the practitioner could try to improve upper airway conditions by loosening or removing the halo jacket. The dorsal fixation has been done, thus the risk of injuring the spinal cord by Hexing the neck is less than immediately after the injury. However, there is no guarantee that it would be safe to Rex the neck, and that the intubating

•

Plan A: With appropriate preparation, extubate the patient, and immediately reintubate with a new, styleted ETT facili­ tated by an indirect laryngoscopy using a VL (e.g. , the GlideScope) . Plan B: In the event of failed reintubation using the GlideScope, patient oxygenation would be maintained with bag-mask-ventilation, using an oropharyngeal airway and two-person technique if necessary. If ineffective, an EGO such as the LMA-Classic would be placed. Plan C: Intubate the trachea using a pediatric flexible bron­ choscope and an Aintree Catheter through the LMA Classic or change the LMA-Classic to a LMA-Fastrach (intubating LMA) for flexible bronchoscopic intubation through the LMA-Fastrach. Rescue plan: Surgical airway; removal of halo frame.

• What Medications Can be Used to Facilitate

the Procedu re?

The use of sedation in the ICU has decreased dramatically in recent years. Very few patients will tolerate a tube exchange without increasing their sedation, unless awake, coopera­ tive, and well topically anesthetized. Compared to elective intubation in the OR, the emergency intubation of critically ill patients carries a much higher risk of complications, for example, post-intubation hemodynamic instability, which is associated with a significant mortality.6 Vasomotor insuf­ ficiency, impaired organ perfusion and microcirculation, an increased sympathetic tone, and lower oxygen delivery (a com­ bination of anemia, hypoxemia, and low cardiac output) place these patients at high risk for profound hypotension, arrhyth­ mia, and myocardial hypoperfusion, to name just the most vital consequences of short-term instability. Careful planning and the choice of drugs have a great impact on preventing hemo­ dynamic instability. Although difficult to predict whether a patient will develop hemodynamic instability, it is important to have a plan in place to treat this early, before it becomes life threatening. Generally, it is not the specific combination of drugs, rather the way they are administered that has the greatest effect on preserving hemodynamic stability. The choice of drugs should reflect the level of sedation desired, anticipated effects on hemodynamics, and their inter­ actions with patient physiology. The ideal drug should have the following characteristics: a short half-life, is metabolized inde­ pendently from liver and kidney function, has minimal car­ diodepressant or vasodilating effects, and can be easily titrated to the desired degree of sedation. Often, no single drug has all these attributes, so a combination of drugs may be necessary. Propofol is a readily titratable agent, increasingly used for long-term sedation in the ICU. It has dose-dependent car­ diodepressant and vasodilating effects.

Ai rway M a nagement of a Patient i n a H a l o-J a c ket with Acute Obstruction of a Reinfo rced Tra c h e a l Tu be

Benzodiazepines have classically been used for sedation in the ICU but tend to have a very long half-life, a dependency on liver metabolism, and the risk of creating delirium. Short­ acting benzodiazepines, such as midazolam, are preferred for procedural sedation. Etomidate is an ultra short-acting sedative with little effect on hemodynamics. Unfortunately, even a single dose can induce adreno-cortical depression, although the clinical significance of this remains uncertain. Ketamine has sedative and analgesic properties, while respiratory function and hemodynamic stability are generally preserved. In contrast to other hypnotic drugs, it causes a disso­ ciative state in which patients tolerate uncomfortable or painful stimuli. Ketamine can cause hallucinations, which has led to substantially decreased use for many years. However, due to the increasingly recognized importance of hemodynamic stability, ketamine has experienced a revival in recent years. Opioids are standard analgesics often used as adjuncts for procedures such as tracheal intubation. While potentially car­ dioprotective (by preventing tachycardia) , in the context of a critically ill patient, they can cause hypotension by suppressing sympathetic drive. Muscle relaxants may be used in conjunction with a seda­ tive/hypnotic agent to optimize intubating conditions pro­ vided an airway assessment has been performed that suggests tracheal intubation will succeed, or that fallback options such as ventilation using a bag-mask or EGD will be possible should intubation fail. With a hemiparesis of 72 hours' duration, suc­ cinylcholine should be avoided in this patient.

PROCE D U RE • What Prepa rations Were Made for the

Tu be Exchange?

Tube exchange using a VL was the chosen technique, as the procedure is the least invasive combined with a good success rate. 2 A GlideScope• was obtained within minutes from the OR for the purpose. The plan was determined as follows: 1 . A second person skilled in airway management (e.g. , respira­ tory therapist, physician) was called to the bedside. 2. One additional nurse was called to assist with calming the patient, administering drugs, charting or calling for addi­ tional help if needed. 3. Tube feed was stopped, and the stomach suctioned through the nasogastric tube. A functional tonsil suction was readied. The patient was placed in 30 degrees head-of-bed elevation position. The bed was moved away from the wall to increase working space at the head of the bed. 4. A call was made to the OR to ensure that a surgeon would be immediately available if needed. 5. The following airway management supplies were gathered at the bedside: An adult-sized tracheal introducer (gum-elastic bougie) ; a complete conventional intubation kit with laryn­ goscopes and Macintosh 3 and 4 blades (lights checked) , a GlideScope•, an adult flexible bronchoscope, ETTs sizes 7- to 9-mm ID; oropharyngeal and nasopharyngeal air­ ways; Ambu• bag with oxygen reservoir, a PEEP valve, an

appropriate size face mask; a #4 and 5 LMA-Classic and LMA-Fastrach" {Intubating LMA) ; lidocaine spray and gel; an emergency cricothyrotomy kit. A lubricated stylet was placed inside an 8 .0-mm ID ETT and bent to an appropri­ ate shape. 6. The following drugs were prepared: propofol infusion, fentanyl, midazolam, and rocuronium. An additional vaso­ pressor was not deemed necessary as a norepinephrine infusion of 0.05 j.Lg·kg- 1 - min- 1 was already running to maintain an adequate mean arterial pressure. 7. It was confirmed that the patient's Fi0 had already been 2 increased to 1 .0. Nasal prongs were applied to the patient, through which oxygen was administered at 1 5 L min - l . The patient was informed about the upcoming procedure. • Ai rway Exchange Proced u re

Before all equipment and additional staff were gathered at the bedside, and despite sedation, the patient deteriorated with severe agitation due to increased respiratory effort. The ETT had to be removed urgently. Passage of an 1 1 -Fr airway exchange catheter was attempted immediately prior to extu­ bation but even this small exchange catheter would not pass through the stenotic area of the ETT. After extubation, assisted face-mask-ventilation was undertaken with a two-handed tech­ nique. Despite the use of an oropharyngeal airway, ventilation was not adequate because of difficulties in applying the face mask within the constraints of the halo frame. A decision was made to proceed with reintubation imme­ diately. To optimize airway management conditions, anesthe­ sia and muscle relaxation were achieved with propofol 1 . 5 mg·kg- 1 and rocuronium 1 mg·kg- 1 (an increase in norepi­ nephrine infusion might be necessary to ensure hemodynamic stability) . The oropharynx was suctioned to remove secretions. Standing behind the patient's head, the practitioner introduced the GlideScope• into the oropharynx without resistance and the glottis was easily visualized on the screen (Grade 1 Cormack­ Lehane laryngeal view) . The new 8 .0-mm ID ETT loaded with a malleable intubating stylet was then advanced under indirect vision using the GlideScope•. It has been suggested that shap­ ing the styleted ETT to a similar curvature as the GlideScope• laryngoscope blade may facilitate the advancement of the ETT which can follow the laryngoscope blade? Unfortunately, the ETT could not be advanced down the trachea. Because of the significant angulation of the styleted ETT, its tip impacted the anterior tracheal wall just beyond the glottis. With oxy­ gen saturation rapidly deteriorating, the procedure had to be aborted and a #4 LMA-Fastrach was inserted easily to provide ventilation. Once the Sp0 had been improved to 96% and would not 2 improve any further, a silicone-based, wire-reinforced 7. 5-mm ID ETT was inserted into the metal lumen of the LMA-Fastrach to the level of the transverse marker on the ETT. The cuff of the ETT was inflated within the lumen of the LMA, and a broncho­ scopic swivel adapter was attached to the proximal end of the ETT. Gentle ventilation with an Ambu bag was delegated to an assistant to help maintain oxygenation during the procedure. A flexible bronchoscope was then inserted through the swivel

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adapter, navigated through the larynx, and further advanced into the trachea until about two centimeters above the carina. The cuff of the ETT was then deflated, allowing for easy ETT advancement over the bronchoscope into the trachea. The tip of the ETT was confirmed by bronchoscopic visualization to be above the carina before its removal. End-tidal capnography was confirmed once the patient's ventilator circuit was connected to the ETT. Ventilation was performed for several minutes until the patient had stabilized. At that point, the LMA-Fastrach was removed over the ETT, using the dedicated tube stabilizer to prevent accidental extubation during this part of the procedure. After ensuring adequate ventilation and oxygenation, it was necessary to replace the Fastrach• tracheal tube (ID 7.5 mm) with a conventional, high-volume, low-pressure cuffed ETT. The Fastrach• tracheal tube is designed to facilitate advancement through the LMA with minimal resistance, but because of its high­ pressure cuff, it is less suitable for long-term use as it is more likely to cause tracheal epithelial injury. In addition, its wire-reinforced nature makes it prone to being bitten and kinked, which is what first led to the need for a difficult tube change in this patient, albeit with a different type of wire-reinforced ETT. An adult­ sized, 1 9-Fr Cook Airway Exchange Catheter was introduced into the Fastrach tracheal tube until the centimeter markings on the ETT and airway exchange catheter indicated that the exchange catheter was approximately 2 em beyond the tip of the ETT. The wire-reinforced ETT was then removed while holding the airway exchange catheter in place. A new 8.0-mm ID ETT was then advanced over the exchange catheter into the trachea under indi­ rect laryngoscopy using a GlideScope. With a 90-degree counter­ clockwise rotation of the ETT, tube passage through the glottis was accomplished without impingement on soft tissue. The ETT cuff was inflated. Correct ETT placement was confirmed with bedside capnography. For this ETT exchange, the procedural time without ventilation was less than 20 seconds for each step, and the patient's Sp0 did not drop below 88%. The patient was then 2 reconnected to the ventilator, which caused the Sp0 to increase 2 to 98%. A post-intubation chest x-ray indicated that the tip of ETT was 4 em above the carina with no evidence of pneumotho­ rax or atelectasis.

S U M MARY An acutely obstructed ETT due to biting on the wire-rein­ forced component represents an indication for immediate tube exchange, since sufficient ventilation is often impossible and there is great risk for developing POPE. A careful, but timely plan is important to safely restore mechanical ventilation with­ out causing additional harm to the patient. In a difficult airway situation, such as fixation of the neck in a halo frame, an exit strategy, for example, emergency surgical airway, should be considered. If time permits, additional staff and all equipment needed should be at the bedside before pro­ ceeding to the tube change procedure. The procedure should not be completed without sedative/ hypnotic and muscle paralysis. If sedation alone is to be used, it should be titrated to achieve just the level needed to toler­ ate the procedure. Over sedation is associated with the risk of hemodynamic instability and complications.

When possible, ETT exchange in a patient with predictors of difficult airway management should be facilitated with an airway exchange catheter. Safety is further enhanced by indi­ rect laryngoscopy using a VL during the exchange procedure, for example, to help avoid impingement of the tip of the ETT on laryngeal structures. After the exchange, correct tube place­ ment should be confirmed by capnography and intra-thoracic complications excluded by chest x-ray.

REFERENCES 1 . Boulain T. Unplanned extubations in the adult intensive care unit: a prospective multicenter study. Association des Reanimateurs du Centre­ Ouest. Am ] Respir Crit Care Med. 1 998; 1 57: 1 1 3 1 - 1 1 37. ' 2. Huang SJ, Lee CL, Wang PK, Lin PC, Lai HY. The use of the GlideScope for tracheal intubation in patients with halo vest. Acta Anaesthesia! Taiwan. 20 1 1 ;49:88-90. 3 . McLean S, Lanam CR, Benedict W, Kirkpatrick N, Kheterpal S, Ramachandran SK. Airway exchange failure and complications with the use of the Cook Airway Exchange Catheter} a single center cohort study of 1 1 77 patients. Anesth Analg. 20 1 3; 1 1 7: 1 32 5 - 1 327. 4. Polderman KH, Spijkstra JJ, de Bree R, et al. Percutaneous dilatational tracheostomy in the ICU: optimal organization, low complication rates, and description of a new complication. Chest. 2003; 1 23 : 1 595- 1 602. 5 . White AN, Wong DT, Goldstein CL, Wong J. Cervical spine overflex­ ion in a halo orthosis contributes to complete upper airway obstruction during awake bronchoscopic intubation: a case report. Can J Anaesth. 20 1 5 ;62:289-293. 6. Mort TC. Complications of emergency tracheal intubation: hemodynamic alterations-part I. J Intensive Care Med. 2007;22: 1 57- 1 6 5 . 7. Walls RM, Samuels-Kalow M, Perkins A . A new maneuver for endotra­ cheal tube insertion during difficult GlideScope intubation. J Emerg Med. 20 1 0;39:86-88.

SELF-EVALUATION QU ESTIONS 3 1 . 1 . Which o f the following methods i s NOT suitable for the exchange of an endotracheal tube in a patient with anticipated difficult airway, such as in a halo jacket? A. video-laryngoscopy B. flexible bronchoscopic intubation C. laryngoscopy with a McCoy blade D. airway exchange catheter E. tracheotomy 3 1 .2 . A possible complication during an airway exchange is A. massive bleeding B. increased abdominal pressure C. acute respiratory failure D. ventilator associated pneumonia (VAP) E. acute airway obstruction 3 1 . 3 . All of the following can be tried if the tracheal tube can­ not be advanced over the tube exchanger through the glottis EXCEPT A. counterclockwise rotation of the tube B. gentle pressure to force the tube through the glottis C. lubrication of the tip of the tube D. jaw thrust E. assist with video-laryngoscopy

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C H A PT E R 3 2

Manage ment of a Patient Ad mitted to I C U with E bola Virus an d I m pen din g Res piratory Failure Louise Ellard and David T. Wong

CAS E PRESENTATION

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I NTRO DUCTION .

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PAT I E NT CO N S I D E RATI O N S .

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AI RWAY CO N S I D E RATIO N S . . .

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CO N S I D E RATI O N S FOR H EALTH CARE WO RKERS .

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S U M MARY . . . . . . . . . . . .

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SELF-EVALUATIO N Q U ESTI O N S .

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A decision was made to secure the airway prior to further deterioration and to avoid rushing in response to a sudden decline. The assembled team comprised of an experienced anes­ thesia practitioner to perform the intubation, an intensive care physician to manage the hemodynamics during intubation, and a critical care nurse to assist. Airway examination revealed a slim build patient (75 kg) with a beard and normal dentition. Reassuring features for an easy direct laryngoscopic intubation included a Mallampati score of II, good mouth opening and thyromental distance of 6 em, and unrestricted head and neck extension.

I NTRODUCTION • What Is EVD?

CASE PRESENTATION A previously well 50-year-old physician presented to hospital with fever, lethargy, nausea, and diarrhea. He had returned from Sierra Leone 5 days prior where he had worked in an Ebola treatment facility. Because of his recent exposure to Ebola virus disease (EVD) and presentation with fevers, he was immediately transferred to the nominated Ebola center in Canada and isolated. A small team of nurses and doctors were assembled to care for him on a rotating shift roster. On admission he was hypovolemic from vomiting and diar­ rhea, requiring treatment with intravenous fluids and low-dose norepinephrine. On day 2 of his admission, he was noted to have escalating oxygen requirements and there was a suspicion that he had coexisting pneumonia. He became increasingly delirious, pulling at lines, and removing supplemental oxygen. An arterial blood gas revealed pH 7.47, pC0 29 mm Hg, and 2 p0 55 mm Hg with an inspired oxygen concentration of 0.70 2 via face mask with oxygen reservoir.

Ebola virus is a member of the Filoviridae virus family that can cause viral hemorrhagic fever, 1 a severe illness associated with high case fatality rates. The first case of Ebola occurred in 1 976 in Equatorial Africa, in two simultaneous outbreaks, one of which was in the Democratic Republic of Congo near the Ebola river after which the disease is named. 2 Since that time there have been 24 outbreaks. • How Severe Was the 201 4 Outbreak?

Since the first cases in the most recent epidemic were notified to the World Health Organization (WHO) on March 2 1 , 20 1 4, this outbreak has caused more cases and more deaths than any previous Ebola epidemic. 3 1he West African countries of Guinea, Liberia, and Sierra Leone were the hardest hit with almost all cases occurring across these three countries. As of August 20 1 5 , there were reported 27,862 cases and 1 1 ,2 8 1 deaths. Case fatality rates in Guinea, Liberia, and Sierra Leone were 66.6%, 45 .05%, and 29.47% respectively4-many times higher than the case fatality rates seen in the 2003 severe acute respiratory syndrome (SARS) epidemic which were approximately 7% to

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1 7%.5 Outside of Africa, Ebola cases were seen in Spain, Italy, the United Kingdom, and the United States.4 Only a single death from Ebola occurred outside of Africa.4

TAB L E 32-1 .

Early a n d Late C l i n ica l Featu res of EVD

Early c l i n i ca l featu res of EVD8 Feve r (often a b r u pt o n set a n d s u sta i n ed) Fati g u e, wea kness Headache Mya l g ia, a rt h ra l g i a H i ccups Conj u nctivitis N a u sea and a n o rexia Dys p h a g i a Dia rrhea

•

• How Is EVD Transm itted?

The index case in an Ebola outbreak is transmitted to humans from the natural hosts, which are thought to be fruit bats. Spread within the human population is through direct human­ human transmission2 via contact with body fluids through mucosal surfaces or skin breaks . 1 •2 The Ebola virus has been isolated from blood, sweat, saliva, vomitus, urine, feces, and semen.1 Humans are infectious from onset of first symptoms for as long as their blood contains virus. 2

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Late c l i n ica l featu res of EVD8 Confu s i o n Seizu res Ch est pa i n Vo m i t i n g a n d/o r d i a rrhea Ra s h B l eed i n g M i scarriage i n p reg n a nt wo m e n Hypovo l e m i a a n d s h o c k Respi ratory d i stress •

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• How Is EVD Diagnosed?

Diagnosis of EVD is based on a history of exposure to EVD within the 2- to 2 1 -day incubation period, clinical features, and laboratory investigations. The real-time polymerase chain reac­ tion (PCR) detects virus in the blood or tissues during the acute phase1 and can provide diagnosis within hours.6

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• What Is the Differential Diagnosis?

Most returned travelers with febrile illness do not have Ebola and other far more common infections including malaria, typhoid fever, and bacterial or other viral infec­ tions should be considered. 3 . 7 However, during an Ebola epidemic, it is important to have a high index of s uspicion for any patients presenting with acute fever plus contact with a clinical case.

PATI ENT CON S I D E RATIONS • What Is the Typical Clinical Picture of a

Patient with EVD?

Initial clinical features of EVD are nonspecific and include fever, weakness, myalgia, headache, anorexia, and hiccups. Subsequently, patients often develop nausea, vomiting, and diarrhea.8 Despite the fact that Ebola was formerly known as viral hemorrhagic fever, less than half of the confirmed cases of EVD have bleeding and when this occurs it would be late in the clinical course. 8 Bleeding is secondary to a consumptive coagulopathy and hepatocellular necrosis causing reduced production of coagulation factors . 1 Bleeding includes ooz­ ing from puncture sites, bruising, bleeding from gums, melena, hematemesis, conj unctival hemorrhage, epistaxis, hematuria, hemoptysis, and unexplained vaginal bleeding (see Table 32- 1) _ 1 -8 Patients with Ebola display intravascular volume depletion and edema-likely related to disruption of the vascular endo­ thelium and capillary leak. 1 In West African centers with labo­ ratory testing facilities, hypoperfusion (evidenced by metabolic lactic acidosis) renal impairment and hypokalemia (secondary to diarrhea) are commonly seen.9

• What Treatment Is Avai lable?

Phase I and II trials for Ebola vaccines are at early stages of development and production? A combination of three mono­ clonal antibodies known as Zmab (Mapp Biopharmaceutical, San Diego, CA) was used as experimental treatment during the recent outbreak. Since specific treatments are not available, supportive care is the mainstay of treatment. Fluid resuscitation and correction of electrolyte abnormalities are vital supportive measures9 and may reduce mortality in this disease. 1 Other treatment compo­ nents include maintenance of blood pressure with vasopressors if required, oxygen supplementation, pain control, nutritional supports, and treatment of secondary bacterial infections.3·7

AI RWAY CO N S I D E RATIONS • Why Might a Patient with EVD Req uire

Tracheal Intubation?

In contrast to other recent viral epidemics such as SARS, Ebola is not commonly accompanied by respiratory symp­ toms.9 Possible reasons for patients developing respiratory dis­ tress might be secondary to fluid overload, respiratory muscle fatigue, or hemoptysis. Transfusion-related acute lung injury could occur. Non-respiratory reasons for requiring intubation include neurological deterioration (e.g. , confusion, and seizures) or to assist management during progressive shock. There is also the potential requirement for a surgical procedure during the course of the patient's illness-for example evacuation of uterus and curettage following miscarriage in a pregnant patient with EVD . Noninvasive ventilation is relatively contraindicated in EVD due to an increased risk of transmission to health care workers

M a nagement of a Patient Ad m itted to I C U with Ebola Vi rus a n d I m pe n d i n g Res p i ratory Fa i l u re

from aerosolization of fluids containing the virus and a high incidence of vomiting and thus aspiration risk. 1 In Guinea's largest public hospital, the intensive care unit (ICU) lacks both piped oxygen and mechanical ventilators.9 There is only a single ICU in Sierra Leone/0 which could theoretically manage a patient with an endotracheal tube. Tracheal intubation and ventilation are not practical options in most West African outbreak locations.9 It is more likely to be employed in a traveler who has returned to a first-world coun­ try. An anesthesia practitioner could be called upon to perform tracheal intubation in such a patient with EVD. • What Preparations Are Req uired Prior to

I ntubating the EVD Patient?

Many lessons were learnt from the SARS epidemic and the subsequent spread to health care workers. In Toronto, Canada, half of the SARS cases involved health care workers. 1 1 Although there are distinct differences in the way EVD is spread, the level of precaution required should not diminish. Tracheal intuba­ tion in a patient with EVD should occur in an isolated area, ideally in an airborne infection isolation room, 1 2 away from other patients and staff, with entry and exit into the room restricted during and immediately after the procedure. 1 2 The number of staff involved should be minimized. 1 2 Plans to secure the airway in a patient with EVD should be made electively in order to avoid the need for a practitioner to rush to a deteriorating patient, which could result in errors made in donning personal protective equipment (PPE) . L l l This might mean that tracheal intubation should occur earlier than you would otherwise consider. The most experienced practi­ tioner available should manage the airway to reduce the time and number of attempts required. 1 1 Although Ebola is not an airborne virus, it is possible that during airway maneuvers, aerosolized saliva or other fluids containing the virus can result in transmission to health care workers. Intubation, extubation, and mask-ventilation are considered to be aerosol-generating procedures1 2 and anyone involved in these procedures in patients with EVD must take extra precautions. The choice lies between a well-fitting N95 mask or a powered air purification respirator system (PAPR, Figure 32- 1) . 1 , 13 A PAPR with a self­ contained filter and blower unit integrated inside the helmet is preferred. 13 The principles of PPE and the specific steps required to correctly don and doff PPE and the powered air purification respirator system are discussed later in this chapter. PPE must provide droplet and contact precautions (full body suit coverage including face mask and goggles or a face shield) . In addition, when airborne precautions are required, a PAPR or N95 mask is substituted for the face mask and goggles. • What Is the Approach to Tracheal I ntubation

in the Patient with EVD?

In most instances, a rapid sequence induction is a sensible choice to prevent aspiration in Ebola patients, given the fre­ quency of gastrointestinal symptoms, as well as reducing poten­ tial aerosolization of fluids during bag-mask-ventilation.

F I G U R E 32- 1 . Powered a i r pu rification res p i rator (PA P R) .

Dedicated equipment should be used, including disposable airway equipment wherever possible.1 2 If advanced airway equip­ ment is needed, consideration could be made to using a dispos­ able video-laryngoscope such as an Airtraq• (Teleflex Medical, Morrisville, NC) or a disposable flexible bronchoscope such as the Ambu• aScope'M (Ambu Inc., Baltorpbakken, Denmark) . • What if Tracheal lntubation Is Expected to be

Difficult?

If intubation is anticipated to be difficult, the choice lies between an asleep or awake airway technique. If a patient has predictors of difficult direct laryngoscopy, the airway could be secured asleep with adjuncts or alternatives to standard direct laryngoscopy such as a tracheal introducer (bougie) or a video-laryngoscope. Intubation via a extraglottic airway device using a bronchoscope and/or Aintree intuba­ tion catheter (Cook Critical care, Bloomington, IN) could be considered. 14 Benefits of an asleep technique include reduced chance of coughing and less need for cumbersome equipment­ all of which must be thoroughly decontaminated after use. The risks of an asleep technique in an Ebola patient with a diffi­ cult airway includes the potential for aspiration with repeated attempts to intubate, or the development of a "cannot intubate, cannot oxygenate" situation. If there is an anticipated difficult direct laryngoscopy plus aspiration risk (e.g. , a pregnant patient with EVD and many predictors of a difficult laryngoscopy) , it would be prudent to consider an awake technique. To the author's knowledge, there

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are no reported cases of awake intubation in patients with Ebola. Clearly, this is a challenging task, with added complexities in the Ebola patient including need to move specialized equip­ ment into the patient's room and thoroughly decontaminate afterwards. Special attention should also be made to reduce the chance of patient coughing which could result in aerosolization of fluids containing virus. Potential for bleeding during airway management should be considered and as careful a technique as possible should be employed by the most experienced practitio­ ner. The nasal route should be avoided if at all possible because of potential bleeding, particularly in the later stage of the EVD. It should be noted that when dressed in PPE with a PAPR, the ability to communicate effectively with other members of the team is severely impaired as is the use of a stethoscope to help confirm endotracheal tube positioning above the carina. 1 1 Disposal end-tidal C0 monitor should b e immediately avail­ 2 able to confirm tube placement within the trachea.

CON S I D E RATIONS FOR H EALTH CARE WORKE RS • How Have Health Care Workers Been

Affected by EVD?

There have been many documented cases of transmission of EVD from patient to health care worker, both in Africa and North America. 1•15 To date, a total of 880 Ebola cases have been seen in health care workers with 5 1 2 deaths.4 • How Can Health Care Workers Mini mize the

Risk of Contracting EVD?

Patients with suspected or proven Ebola should be isolated and the patient room should have a separate anteroom for donning and doffing PPE. The number of health care workers who come into contact with such patients should be restricted, necessitating longer shifts from fewer practitioners.13 Length of shifts is partly limited by the fact that PPE is hot and cumbersome, restricting the time that doctors and nurses can work within an isolation ward.16 • What Can be Done at Hospita l Level?

It is vital that hospitals have advanced planning that deter­ mines where patients with suspected or proven Ebola virus will be cared for, by whom, and with detailed PPE protocols. Guidelines have been published for Ebola patients cared for in US hospitals1 2' 13 and in Europe. 17 Guidelines are also avail­ able for use in Africa where resources are significantly more limited.8 Even in countries without previous Ebola cases, the risk of transmission remains throughout the entire period of the epidemic. In countries outside of Africa where the likely number of cases is very small, one major hospital in each region should be designated as the Ebola center for potential patients. • What PPE Should be Used?

The principles of correct use of PPE include that the health care worker should have no skin exposed: the PPE must be placed in correct order and must not be later modified while in the patient care area. 13 The health care worker must have specific

training in donning and doffing PPE and must have demon­ strated competency in these practices. Each step of donning and doffing must be supervised by a trained observer. 13 Sufficient time should be allowed for donning and doffing of PPE, 13 which would likely have an impact on timing of any interven­ tions, including airway interventions. Removal of PPE is a par­ ticularly high-risk time, with most cases of health care worker transmission occurring during breaches of PPE removal. 1 • What Are t h e Specific Steps for Don ning

PPE?

The Center of Disease Control (CDC) has published guidelines specific for US hospitals, based on either use of the PAPR or N95 respirator. 13 The WHO have published guidelines on don­ ning and doffing PPE. 18 1. Scrub suit and dedicated shoes are put on in the changing room with removal of jewelry, and lanyards, etc. 2. Perform hand hygiene 3. Place first set of gloves 4. Put on coveralls with hood ensuring that first set of gloves are under sleeves of coveralls 5. Put on face mask and either goggles or a face shield. If the patient has respiratory symptoms or there will be a respira­ tory intervention, that is, intubation, a N95 mask or PAPR should also be worn 1 6. Put on head and neck covering (hood of coveralls) 7. Put on disposable waterproof apron over coveralls 8. Put on second pair of gloves ensuring cuffs are secure over gown • What Are the Specific Steps for Removi ng

(Doffing) PPE?

Waste containers for disposal of PPE must be available, with separate containers for reusable items. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15.

Perform hand hygiene on gloved hands Remove waterproof apron Perform hand hygiene on gloved hands Remove head and neck covering taking care to avoid contaminating your face Perform hand hygiene on gloved hands Remove coverall and outer pair of gloves Perform hand hygiene on gloved hands Remove face shield by strap behind head Perform hand hygiene on gloved hands Remove face mask Perform hand hygiene on gloved hands Remove rubber boots without touching them (with boot remover) Perform hand hygiene on gloved hands Remove inner set of gloves Perform hand hygiene

• How Was I ntubation Managed in the

Presented Case?

Other than the three team nominated members (anesthesia practitioner, intensive care physician, and critical care nurse)

M a nagement of a Patient Ad m itted to I C U with Ebola Vi rus a n d I m pe n d i n g Res p i ratory Fa i l u re

no one else was present in the room during intubation. Those team members donned PPE and a PAPR according to the hos­ pital protocol. The airway was not anticipated to be difficult and as such Plan A was to perform a rapid sequence induction and direct laryngoscopy, with an intubating stylet and tracheal tube intro­ ducer available. If that failed, Plan B was to use a disposable Airtraq• video-laryngoscope. If that failed, Plan C was to place an extraglottic airway and proceed to an asleep bronchoscopic intubation via the extraglottic airway. Other than the flexible bronchoscope, all equipment for these plans was brought into the patient room. In spite of the potential for rapid oxygen desaturation with the onset of apnea, a decision was made to omit nasal prong oxygenation during the airway management sequence. Denitrogenation was achieved with spontaneous breathing via a well-applied face mask. A rapid sequence induction was performed using fentanyl 1 00 flg, propofol total dose 1 2 0 mg, and succinylcholine 1 00 mg. Bag-mask-ventilation was not performed. A Cormack-Lehane Grade 1 laryngeal view was obtained with a Macintosh laryngoscope with a disposable blade (Heine• XP Disposable Laryngoscope Blades, Heine USA Ltd., Dover, NH) , the endotracheal tube was placed and its position confirmed with capnography. During intubation a minor hemodynamic disturbance was managed with a tem­ porary increase in norepinephrine infusion. Post intubation, the tracheal tube was secured and the patient was sedated with infusions of midazolam and morphine. Once 1 5 minutes had elapsed after the intubation, the anes­ thesia practitioner and intensive care physician left the patient room and carefully removed PPE in the exit anteroom. All air­ way equipment was disposed of, including the Airtraq• that wasn't used. The patient remained ventilated for a total of 5 days dur­ ing which time antibiotic treatment continued for pneumo­ nia. Fluid and electrolyte status was optimized. Steady clinical improvement occurred and tracheal extubation took place on day 7 of his hospital stay and discharged after 3 weeks.

than the coronavirus responsible for the SARS epidemic, the case fatality rate is higher. 19 • What Are the Sym ptoms in a Patient with

MERS?

The initial symptoms in MERS are those of a nonspecific febrile respiratory tract infection.19 The clinical picture can vary from asymptomatic infection to multi-organ failure and death. 2 ° Commonly reported symptoms include fever (7 1 %), cough (68%) , dyspnea (66%) , and gastrointestinal symptoms (32%) . 20 People with comorbidities, such as diabetes, chronic lung disease, and immunocompromised patients are at higher risk of severe disease. 23 • How Should Health Workers Manage

Patients with MERS? Are There Differences from Ebola Patients?

In contrast to the Ebola virus, community transmission of MERS is uncommon. Rather, transmission in health care set­ tings has been a feature of this outbreak. 23• 24 The WHO recom­ mends that health care workers caring for patients with MERS use droplet and contact precautions (full body suit coverage including face mask and goggles or a face shield) , 20'22 and because the possibility of airborne transmission is very low, 22 the WHO only recommend airborne precautions (i.e., the additional use of a PAPR or N95 mask) for aerosol-generating procedures (Figures 32-2 and 32-3) . 1 9 Conversely, the CDC recommends

• Now That the Cu rrent Ebola Epidemic Has

Ended, What Is Next?

Middle East respiratory syndrome (MERS) was first reported in Jeddah, Saudi Arabia in June 20 1 2 . 1 9 The causative agent is a novel coronavirus known as MERS-CoV 19'20 As of September 23, 20 1 5 , a total of 1 570 cases have been confirmed with a case fatality rate of 35%. More than 85% of cases have been in Saudi Arabia. 19 There has been spread to Europe, the United States, China, and Asia2 1 with all cases linked to travel or resi­ dence in the Middle East. • How Is MERS Transm itted?

Similar to Ebola, MERS is also a zoonotic disease with drom­ edary camels being the suspected animal reservoir. 19 Person­ to-person spread occurs through droplet transmission from respiratory tract secretions. 22 Although MERS is less contagious

F I G U R E 32-2. Perso n a l protective eq u i pment with face m a s k (WITHOUT Aerosol preca utions).

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for spread of infection to health care workers and must be done with meticulous precautions. Hospitals also need to have pre­ determined arrangements including a physical location to look after such patients, a designated treating team, and appropriate training in correct use of PPE.

REFERENCES

F I G U R E 3 2 - 3 . Perso n a l protective eq u i pment w i t h PAP R (add ition of a i rborne preca utions).

that in addition to contact and droplet precautions, airborne precautions are used for all patient care activities. 20 Like Ebola, there is no specific vaccine or treatment currently available and thus treatment of MERS is supportive. 20•24

S U M MARY The 20 1 4 outbreak of EVD was the largest in its history with over 27,000 cases reported. The vast majority of these cases were seen in West Africa, although hospitals in the United States and Europe also treated returned travelers with EVD. Failure to promptly identifY and isolate suspected Ebola cases in returning travelers could lead to new outbreaks. Although respiratory symptoms are uncommon and EVD is not airborne, extra precautions should be taken in any patients who require an aerosol-generating procedure, such as tracheal intubation. If intubation is required, it should be performed by the most experienced practitioner available, in an elec­ tive fashion in order to allow the treating practitioners time to safely don PPE with aerosol precautions such as a PAPR or N95 mask. A clear airway management strategy including initial Plan A and alternative plans should be stated and under­ stood by the entire team prior to commencing. Intubation per­ formed without bag-mask-ventilation during the sequence is ideal in order to minimize aerosolization of fluids, although it may be needed berween attempts if hypoxemia is imminent or has occurred. Doffing of PPE is a particularly high-risk period

1 . Funk DJ, Kumar A. Ebola virus disease: an update for anesthesiologists and intensivists. Can J Anaesth. 20 1 5 ;6 2 ( 1 ) : 80-9 1 . 2. WHO. Ebola virus disease fact sheet. Available at: http://www.who.int/ mediacentre/factsheets/fs 1 03/en/. Updated April 20 1 5 . Accessed August 1 0, 20 1 5 . 3 . Briand S , Bertherat E , Cox P, e t a!. The international Ebola emergency. N Eng!] Med. 20 14;37 1 ( 1 3) : 1 1 80-1 1 83 . 4. WHO. Ebola situation report-August 5 , 20 1 5 . Available at: http://www .who.int/csr/disease/ebolalen/. Accessed August 1 0 , 20 1 5 . 5 . WHO. Summary o f probable SARS cases with onset o f illness from 1 November 2002 to 31 July 2003. Available at: http://www.who.int/ csr/sars/country/table2004_04_2 l len/. Updated December 3 1 , 2 0 1 3 . Accessed September 3 0 , 20 1 5 . 6. Frieden TR, Damon I , Bell B P, Kenyon T, Nichol S . Ebola 20 1 4-new challenges, new global response and responsibility. N Eng! J Med. 20 1 4; 3 7 1 ( 1 3) : 1 1 77- 1 1 80. 7. CDC. Ebola Virus Disease (EVD) information for clinicians in US healthcare settings. Available at: http://www.cdc.gov/vhf/ebola/healthcare­ us/preparing/clinicians.html20 1 5 . Updated April 1 , 20 1 5 . Accessed August 4, 20 1 5 . 8 . WHO. Clinical management o f patients with viral haemorrhagic fever-a pocket guide for the front-line health worker. Published 20 1 4 by WHO . Pocket guide Publication b y WHO . 9. Fowler RA , Fletcher T, Fischer WA, e t a l . Caring for critically ill patients with Ebola virus disease. Perspectives from West Africa. Am J Respir Crit Care Med. 20 1 4; 1 90{7):733-737. 10. Emergency. Ebola treatment unit in Goderich. Available at: http:// www. emergency. it/ sierraleone/ ebo la- treatm ent-unit -goderich. html. Updated June 20 1 5 . Accessed August 21 , 20 1 5 . 1 1 . Nanji KC, Orser BA. Managing Ebola: lessons learned from the SARS epidemic. Anesth Analg. 20 1 5 ; 1 2 1 (3) : 834-835. 1 2 . CDC. Infection prevention and control recommendations for hospital­ ized patients under investigation {PUis) for Ebola Virus Disease (EVD) in U.S. hospitals. Available at: https://www.cdc.gov/vhf/ebola/healthcare-us/ hospitals/infection-control.html. Updated February 1 2 , 20 1 5 . Accessed August 4, 20 1 5 . 1 3 . CDC. Guidance o n personal protective equipment t o b e used by healthcare workers during management of patients with Ebola virus disease in US hospitals, including procedures for putting on {Donning) and removing {Doffing) . Available at: https:/ /www. cdc. gov/vhf/ebola/ healthcare-us/ppe/guidance.html. Updated April 25, 20 1 5 . Accessed July 28, 20 1 5 . 1 4 . Wong DT, Tang JJ, Mak HY, Jagannathan N . Use o f intubation introduc­ ers through a supraglottic airway to facilitate tracheal intubation: a brief review. Can ]Anesth. 20 1 2; 5 9:704-7 1 5 . 1 5 . Grocott H P. Ebola and the journal's response t o 'the most severe acute health emergency seen in modern times'. Can ]Anaesth. 20 1 5;62( 1 ) : 1 -2. 16. Chan MT. Ebola virus disease in West Africa-no early end to the out­ break. N Eng!] Med. 20 1 4;37 1 ( 1 3) : 1 1 83- 1 1 8 5 . 1 7 . SHC. Practical recommendations t o the attention of healthcare profession­ als and health authorities regarding the identification of and care delivered to suspected or confirmed carriers of highly contagious viruses {of the Ebola or Marburg type) in the context of an epidemic outbreak in West Africa. Superior Health Council. 20 1 4 . Available at: http://www. abihh.be/ pdf2/ ebola. pdf. 1 8 . WHO. How to put on and how to remove personal protective equipment­ posters. Available at: http:/ /www.who.int/csr/resources/publications/ebola/ ppe-steps/ en/. 1 9. Gostin LO, Lucey D. Middle East respiratory syndrome: a global health challenge. JAMA. 20 1 5 ; 3 1 4 (8):771 -772. 20. Alsolamy S. Middle East respiratory syndrome: knowledge to date. Crit Care Med. 20 1 5 ;43 (6) : 1 283- 1 290. 2 1 . Countries with laboratory-confirmed MERS cases. Australian Government Department of Health. 20 1 5 . Available at: http://www.health.gov.au/inter­ net/main/publishing.nsf/Content/ohp-mers-cov-countries-lab-confirmed. htm. Updated October 2, 20 1 5 .

M a nagement of a Patient Ad m itted to I C U with Ebola Vi rus a n d I m pe n d i n g Res p i ratory Fa i l u re 22. Pavli A, Tsiodras S, Malrezou HC. Middle East respiratory syndrome coronavirus (MERS-Co V): prevention in travelers. Travel Med Inftct Dis. 20 1 4; 1 2(6 pt A) : 602-608. 23. WHO. Middle East Respiratory Syndrome (MERS). Australian Government Department of Health. Available at: http:/ /www.healrh.gov .au/mers-coronavirus. Updated September 24, 20 1 5 . 24. WHO. Middle East repiratory syndrome coronavirus (MERS-CoV). Available at: http://www.who.int/emergencies/mers-cov/en/. Updated June 20 1 5 .

SELF - EVALUATION QU ESTIONS 32. 1 . Which o f the following i s considered the basic personal protection equipment in managing a patient with Ebola virus? A. N95 or powered air purification respirator system B. contact: gloves, gown, hat, shoe-covers C. eye protection: goggles or face-shields D. pens, pagers, or personal items should not be brought into or out of the room E. all of the above. 32.2. All of the following principles in managing the airway of a patient with Ebola are true EXCEPT A. Awake bronchoscopic intubation is the preferred air­ way technique for all Ebola patients with a potential difficult laryngoscopic intubation. B . Intubation should be undertaken by an experienced airway practitioner, wearing full protection.

C. It is necessary to reduce the risk of aerosolization of Ebola droplets during the process of intubation. D. It is critical that the health care workers apply and remove personal protection equipment prior to and after intubating the patient. E. Bag-mask-ventilation, nebulization, and application of topical airway anesthesia are to be avoided. 32.3. All of the following should be in the airway management team for patients with Ebola EXCEPT A. an experienced airway practitioner B. an experienced surgeon for a surgical airway C. an experienced paramedic D. an ICU nurse E. an intensivist

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Performin g an E lective Percutaneous Dilationa l Tracheotomy in a Patient on Mechanical Ventilation Angelina Guzzo, Liane B. Johnson, and Orlando R. Hung

CAS E PRESENTATION

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I NTRO D U CTION .

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COM P LICATI ONS . . . . . . . . . . . . . . . .

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POST-TRACH EOTOMY MANAG EMENT . .

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S U MMARY .

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CASE PRESENTATION A 28-year-old, previously healthy female was thrown off an all terrain vehicle (ATV) and sustained blunt trauma to her chest. Her injuries included a Bail chest with fractures of the right first and second ribs, a pulmonary contusion, as well as a right femur fracture and ruptured spleen. Following a splenec­ tomy on the first night, she stabilized hemodynamically and subsequently underwent an open reduction internal fixation of the fractured femur. On the 1 Oth day, she failed an extubation attempt due to hypoxemia. Currently she is being ventilated with a pressure support of 1 2 em H 0, positive end-expiratory 2 pressure (PEEP) of 5 em H 0 and Fi0 0 . 5 0 . Her ABG shows 2 2 a pH 7.47, PC0 37 mm Hg, P0 60 mm Hg, and HC0 2 2 3 26 mEq·L - l . Her respiratory rate is 20 breaths per minute. All other vital signs are stable. You have been consulted to help perform a tracheotomy.

I NTRODUCTION • Why Would You Perform a Tracheotomy on

Th is Patient?

Local changes occur in airway mucosal surfaces following as little as 2 hours of endotracheal intubation. These pathophysiologic changes include a well-documented progression of mucosal ulceration, pressure necrosis, granulation tissue with subse­ quent healing, fibrosis, and occasionally stenosis. 1 ' 2 1here exists no consensus on the ideal timing of performing a tracheotomy in the hopes of minimizing long-term airway complications,3 but standard practice dictates a range of 7 to 10 days follow­ ing the initial intubation. While a Cochrane review4 showed lower mortality in an early tracheotomy group ( < 1 0 days) and a higher propensity for discharge from the ICU at day 28, a meta-analysis found no difference in mortality, length of ICU stay, or risk of ventilator-acquired pneumonia when compared to the late tracheotomy group (> 1 0 days) but did find that the duration of sedation was decreased.5 Notwithstanding, in a retrospective study of early versus late tracheotomy in trauma patients, Hyde et al.6 showed a significantly lower length of ICU stay, ventilator-acquired pneumonia, and ventilator days in the early group. However, in this study early tracheotomy was shorter than the previous analyses, < 5 days. Thus, if pro­ longed intubation is predicted based on patient circumstances such as trauma, for example, a high spinal cord injury, then earlier conversion to tracheotomy may be considered. • What Are the Advantages of a Tracheotomy

Over a Prolonged Translaryngeal I ntubation?

The potential advantages of a tracheotomy over a prolonged translaryngeal intubation include less direct endolaryngeal injury, a potentially decreased risk of nosocomial pneumonia in certain patient subgroups,3·7 more effective pulmonary toilet,

Perfo rm i n g a n E l ective Perc uta neous D i lati o n a l Trac h eotomy i n a Pati ent on Mec h a n ica l Ve ntilation

and possibly decreased airway resistance for promoting wean­ ing from mechanical ventilation. Additional benefits include improved patient comfort, communication and mobility, increased airway security, decreased requirements for sedation, better nutrition, and earlier discharge from ICU.8•9

AI RWAY CO N S I D E RATIONS • If a Tracheotomy Is Going to be Performed

Anyway, Why Is It I mporta nt to Know Whether Th is Patient Has a Difficult Airway or Anatom ical Featu res Associated with Difficult La ryngoscopic I ntu bation?

In fact, it is extremery important to assess the airway prior to performing a tracheotomy. When performing either a surgi­ cal tracheotomy (ST) or a percutaneous dilational tracheotomy (PDT) , during the procedure the indwelling endotracheal tube (ETT) must be carefully withdrawn above the tracheot­ omy site to accommodate insertion of the tracheostomy tube. During this maneuver, there is a potential risk of premature extubation and need for controlled ventilation and reintuba­ tion. Ultimately, preparing for a successful procedure requires a thorough chart review, patient airway assessment, proper equipment preparation (including the difficult airway cart if the patient has a history of difficult laryngoscopic intubation) , and proper patient positioning. Attention to these factors and hav­ ing qualified, briefed assistants will help minimize the need for emergency airway access should unanticipated difficulty arise. While the importance of assessment and preparation is well accepted in airway management, the dynamic nature of the upper airway anatomy is often overlooked. Surgical procedures or radiotherapy that alter skeletal or soft tissues of the head and neck can change the upper airway anatomy, making laryngo­ scopic intubation difficult. A high index of suspicion should be applied to patients who have undergone recent surgery of the temporo-mandibular joints and mandible, reconstructive orthognathic or cosmetic surgery, fusion of the cervical spine, or patients with severe burns to the head and neck. 10 ' 1 1 For example, Coonan et al. 1 2 reported a patient with an unantici­ pated difficult laryngoscopy secondary to contracture of the temporalis muscle causing ankylosis of the jaw several weeks following a temporal craniotomy. Many patients presenting for tracheotomy will have undergone recent surgery: in evaluating these patients, the potential for such dynamic changes to what may previously have been an easily managed airway should always be considered.

PREPARATION A N D TECH N I Q U ES • Describe the Anatomy of the Ai rway with

Respect to Perform ing a PDT

Surgical access to the trachea through the anterior neck requires knowledge and recognition of surface anatomy land­ marks of the larynx as well as the important adj acent struc­ tures in the neck. Equally important, dexterity and familiarity with flexible bronchoscopy is essential as a guide to safely complete a PDT. Easily palpable landmarks include: the hyoid bone, situated high in the neck just below the submental space and having a primary suspensory role for the airway; the thyroid notch, most prominent in adult males and identifYing the superior aspect of the thyroid cartilage; the cricoid cartilage, the only complete ring, and bridged by the cricothyroid membrane to the inferior portion of the thyroid cartilage (Figure 33- 1 ) . With the neck extended, palpation inferiorly from the cricoid cartilage may reveal proximal tracheal rings and the thyroid gland. The vocal cords are protected by the body of the thy­ roid cartilage anteriorly and attach to the arytenoid cartilages which articulate from the postero-superior margin of the cri­ coid ring. An experienced practitioner must perform flexible bron­ choscopy to identifY the level of important internal laryngeal structures (supraglottis, glottis, and subglottis) and to trans­ illuminate the area berween the second to fourth tracheal

• How Would You Assess This Patient's Airway?

The patient's chart should be reviewed to determine if there is a history of difficult laryngoscopic intubation or difficult bag­ mask-ventilation. Chapter 1 has reviewed anatomic and physi­ ologic factors which may predict difficulty with each. The neck should also be assessed for C-spine stability and other factors that could create difficult surgical conditions such as cervical flexion deformity, obesity, previous neck surgery or radiation therapy, active neck infection, or tumor.

F I G U R E 33- 1 . S u rg ic a l a i rway a natomy: Thyro i d ca rti l a g e (A); cricothyro i d m e m b ra n e (B); a n d cricoid ca rti l a g e (C) . (Reprod uced with perm ission from Wa l l RM, Luten RC, M u rphy M F, et al. Manual of Emergency A irway Management, 2nd ed. P h i l a d e l p h i a , PA: L i p p i n cott Wi l l ia m s & Wi l l ia m s; 2004.)

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rings. In patients with poorly palpable surface anatomy, transillumination and visual confirmation of the guide needle within the trachea will ensure proper positioning of the tra­ cheostomy tube.

• Compare and Contrast the Different Sites

at Which Surgical Airway Access Can be Performed

Surgical access to the airway can be gained at the cricothy­ roid space, subcricoid space, or between any of the tracheal rings. To secure an emergency airway rapidly, a cricothyrot­ omy is preferable in the adult patient because the cricothyroid membrane is superficial, easily identifiable, and thus easiest to access (see Chapter 1 4) . 3 Controversy has existed about the long-term use of cricothyrotomy due to early reports of sub­ glottic stenosis (SGS) , limiting its use to emergency airway access. 13 However, reexploration of this notion in a prospec­ tive study involving 1 1 8 patients has shown the incidence and severity of complications to be similar between traditional tra­ cheotomy and cricothyrotomy techniques. 13 A review of the literature from 1 978 to 2008 identified 20 published series in which emergency cricothyrotomy was performed with an overall SGS rate of 2 . 2 % . 14 The same authors identified only two studies examining the complications associated with con­ verting a cricothyrotomy to tracheotomy and reported it as 53%. Contrary to standard ASA difficult airway algorithm and Advanced Trauma Life Support teaching, at least one center uses ST for emergency airway management more often than cricothyrotomy. 15 The first modern-day ST performed by Chevalier Jackson in the early 1 900s involved entering the trachea at the second or third tracheal rings. 16 He advocated avoiding the first and second tracheal rings due to a high incidence of subsequent SGS.17 Current consensus dictates that in ideal circumstances, a tracheotomy is performed between tracheal rings two to four. Injury to the first ring or cricoid cartilage may increase the risk of SGS whereas placement too low may predispose to erosion of the anterior tracheal wall and possible creation of a tracheoinnominate fistula. 18 The first percutaneous tracheotomy not requiring neck dis­ section was described in 1 95 5 by Shelden, 1 9 during which a slotted needle was introduced blindly into the tracheal lumen. Subsequently, several deaths were reported secondary to lacera­ tion of vital structures in proximity to the airway. 20 Toye and Weinstein2 1 performed the first tracheotomy using a Seldinger technique where a single tapered dilator was introduced with a recessed cutting blade. In 1 98 5 , Ciaglia et al. 22 introduced a dilational Seldinger technique which has since been refined and has now become one of the most popular techniques for PDT. 2 3 Initially, PDT was performed in the immediate subcricoid space, 22 but in a follow-up publication, the space between the first and second tracheal rings was advocated. 24 But, the more distal approach (beyond the second ring) was not recommended due to the risk of bleeding from the thy­ roid isthmus24 or from puncture of an aberrant, high-riding innominate artery.

• Describe the Different Tech niq ues Used

to Perform an Elective Surgica l Airway (For Techniq ues to Manage an Emergency Surgical Airway, Refer to Chapter 1 4)

A. Surgical Tracheotomy (Please See Chapter 1 5 for Details of the Technique) ST is usually performed under general anesthesia in the operating room. The neck is extended to elevate the trachea into the neck. Depending on the length of the patient's neck, a horizontal incision is generally made crossing the midline approximately 2 em above the sternal notch. The subcutaneous tissue and platysma muscle are divided trans­ versely. The remainder of the dissection is performed lon­ gitudinally through the superficial cervical fascia and the linea alba dividing the strap muscles. Lateral retraction of the strap muscles often reveals the thyroid isthmus, which is commonly divided to provide better surgical access and to minimize the risk of bleeding by its manipulation. 18 Various types of tracheal incisions have been used. Quite frequently, a superiorly based Bjork flap or window is made by unroofing the second or third tracheal ring. To avoid damaging the indwelling ETT cuff during tracheotomy, it is a common practice to deflate the cuff and purposely advance the ETT distally into the right mainstem bronchus prior to making an incision in the trachea. Following tracheal access, the ETT is withdrawn under direct vision to just above the tracheotomy site by the airway practitioner. Superior retraction on the cepha­ lad tracheal ring with a tracheal hook and spreading of the tracheal incision facilitates subsequent insertion of the tra­ cheostomy tube. Endotracheal positioning is confirmed by connecting the tracheostomy tube to the ventilatory circuit and con­ firming the presence of end-tidal C0 • These final mea­ 2 sures, in addition to assessing lung compliance and airway pressures, are ascertained prior to the complete removal of the ETT. The tracheostomy tube is then secured with sutures, and a tie passed around the neck. 18 B . Percutaneous Dilational Tracheotomy The PDT technique is easily performed at the bedside with two practitioners: one performing the tracheotomy while the second provides ventilation and oxygenation. It is essential to continuously monitor vital signs including pulse oximetry, blood pressure, heart rate, and rhythm. The patient should be ventilated with 1 00% oxygen through­ out the procedure. The patient's current sedative regime can be supplemented with an opioid and an intravenous sedative/hypnotic such as a benzodiazepine or propofol. 2 5 Pharmacologic muscle relaxation during needle inser­ tion is desirable to help prevent inadvertent puncture of the posterior tracheal wall or coughing during the inser­ tion of the tracheotomy tube. For continued mechanical ventilation during the procedure, after ETT cuff deflation, adjustments are made to tidal volume, respiratory rate, and PEEP to compensate for the air leak. At our institution, the patient is manually ventilated with a bag-mask device and 1 00% oxygen throughout.

Perfo rm i n g a n E l ective Perc uta neous D i lati o n a l Trac h eotomy i n a Pati ent on Mec h a n ica l Ve ntilation

Flexible bronchoscopy through the ETT to facilitate PDT insertion was introduced in 1 989. 26 Bronchoscopy allows visu­ alization of the needle entering the trachea, helping to confirm its location in the midline at the correct tracheal interspace, ensuring that the ETT is not punctured or impaled, and also minimizing the risk of damaging the posterior tracheal wall. 2 3 In the case of accidental premature extubation, the broncho­ scope can also be used to guide ETT reinsertion. There may also be a role for videoscopic bronchoscopy during teaching as there is a "learning curve" to performing PDT. 20 The disadvan­ tages of flexible bronchoscopy include difficulties with ventila­ tion and oxygenation leading to hypercarbia and hypoxemia2 3 and the potential for damage to the bronchoscope by the needle or guidewire. Other adjuncts such as ultrasound and capnography are increasingly being used to aid successful PDT. Ultrasound can help to determine the site of tracheal puncture prior to PDT by identifYing the appropriate level as well as structures at risk of hemorrhage, such as variant innominate artery anatomy. 27 Kollig et al. 2 8 used ultrasound to determine the site of puncture followed by confirmatory bronchoscopy; ultrasound findings changed the tracheal puncture site in 24% of the procedures, primarily due to identification of subcutaneous blood vessels. A retrospective observational study comparing 95 ultrasound­ guided PDTs with bronchoscopic confirmation to 82 cases without subsequent bronchoscopic confirmation resulted in a significantly longer procedure time ( 1 3 . 9 vs. 1 0.7 minutes) and more oxygen desaturation to < 90% ( 1 6.8% vs. 3.7%) in the bronchoscopic group. 2 9 Bronchoscopy was used in three patients originally enrolled in the ultrasound-only group, one patient of which was found to have the wire directed cranially. Although ultrasound offers many advantages, a prospective ran­ domized control trial is needed.3° Capnography has been used to confirm tracheal needle placement and has been shown to be equally effective as bronchoscopy.31 Portable monitors are now available to quantifY C0 at the bedside. 2 Prior to tracheal puncture, the ETT must be withdrawn to avoid cuff laceration or ETT impalement. Besides bronchos­ copy, alternative methods have been advocated to confirm adequate ETT withdrawal before tracheal puncture. These include use of direct laryngoscopy with a tube exchanger, ETT cuff palpation, and pre-measured blind withdrawal. 2 3 In 2000, our group described a technique using a lightwand (Trachlight'" [Laerdal Medical Inc. , Wappingers Fall, NY] ) , a common and inexpensive intubation device, as an alternative to bronchoscopy to facilitate the PDT. The lightwand device can be advanced into the ETT. In order to place the lightbulb of the lightwand at the tip of the ETT, the number markings on the lightwand shaft must be lined up with those on the ETT. Anterior neck transillumination3 2 can then be used to confirm adequate withdrawal of the ETT prior to the needle puncture. Since the original report of PDT by Ciaglia, the procedure has undergone three modifications. These include the move­ ment of the tracheal cannulation site to one or two interspaces caudal to the cricoid cartilage; the use of bronchoscopy and the use of a single, beveled dilator instead of multiple dilators. 2 3 While currently several kits are available for the Ciaglia sin­ gle-dilator technique, only the Ciaglia Blue Rhino• kit (Cook

Critical Care, Bloomington, IN) will be presented below in more detail. Under optimal conditions, the neck is extended and the surgical field is aseptically prepared (Figure 33-2A) . The tra­ cheostomy tube cuff must be checked for leaks and then well lubricated. The first or second tracheal interspace is located and local anesthetic injected subcutaneously. A vertical skin incision is made in the midline from the level of the cricoid cartilage caudally 1 to 1 . 5 em (Figure 33-2B) . The wound is dissected bluntly to the subcutaneous fascia using a hemostat. The ETT should be withdrawn to 1 em above the anticipated needle inser­ tion site under bronchoscopic guidance. A 17 -gauge sheathed introducer needle is advanced in a midline, posterior, and cau­ dad direction. The tracheal air column is identified when air is aspirated into a fluid-filled syringe (e.g. , 2-3 mL of lidocaine) (Figure 33-2C) . At this time the ETT is advanced and with­ drawn 1 em to verifY that the needle does not concomitantly move, to rule out inadvertent impalement of the ETT. The outer sheath of the introducer needle is then advanced into the trachea while the introducer needle is removed. The fluid­ filled syringe is then reattached to the sheath and its position in the trachea is reconfirmed by free flow of air. To minimize the responses to the subsequent insertion of the dilator, the lidocaine in the syringe is instilled into the trachea. The syringe is removed and a 1 .32-mm diameter J tipped guidewire is advanced through the sheath into the trachea (Figure 33-2D) . The sheath i s then removed. Although not specified by the manufacturer, in our experience, it is beneficial to make a sec­ ond cut around the guidewire with the scalpel to provide room for the dilator. A short 1 4 French introducing mini-dilator is advanced over the guidewire using a slight twisting motion and then removed. The Ciaglia Blue Rhino" dilator, after soaking in water, is then advanced over the guide wire while maintaining the wire position (Figure 33-2E) . The dilator and guide wire are advanced together into the trachea up to the black skin level mark. The dilator is withdrawn and advanced several times to help create the stoma, whereupon it is removed. The lubricated tracheostomy tube with its internal dilator is then inserted over the guide wire and advanced as a unit until it reaches the flange (Figures 33-2F and 33-2G) . The guide wire and dilator are then removed leaving the tracheostomy tube in situ (Figure 33-2H) . The tracheostomy tube cuff is inflated and its proximal connec­ tor is attached to the ventilator (Figure 33-21) . Once insertion into the trachea has been confirmed by end-tidal C0 detec­ 2 tion, the translaryngeal ETT is removed. Other PDT techniques have been developed. 8· 2 3 The Rapitrach kit (Surgitech Medical, Sydney, Australia) uses a dilating tracheotome with blades designed to slide over the guidewire into the trachea. To create a stoma, it is necessary to squeeze the blades opened.33 Unfortunately, the Rapitrach method resulted in a high rate of posterior tracheal wall and balloon cuff tears and was removed from the US market. 23 The Griggs technique uses a Howard-Kelly forceps that is introduced into the tracheal lumen with the guidewire.34 A stoma is created when the forceps are opened, similar to the Rapitrach method, but without a cutting blade. This tech­ nique is popular in South America and Europe. 23 A third method is a translaryngeal approach developed by Fantoni

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Ai rway M a n a g e m e n t in the I nte n s ive Ca re U n it (ICU)

F I G U R E 3 3 - 2 . Percuta neous d i latio n a l tra c heotomy. (A) M o n itors a re a p p l ied a n d the n e c k i s exte n d ed a n d pre p ped. (B) T h e fi rst or secon d tra c h e a l i nterspace i s identified, a n d a vertica l s k i n i nc i s i o n i s m a d e i n the m i d l i ne from the l evel of the cricoid ca rti l a g e ca u d a l ly 1 to 1 .5 e m . (C) An i ntrod ucer need le is i n serted with a syri n g e a n d a s p i rated u n t i l a free fl ow of a i r is o bta i ned. (D) A J ti pped g u idewire is g u ided i nto the tra c h ea t h ro u g h the need l e . (E) A d i lator is adva nced over the g u i dewi re. (F, G) The tracheostomy tu be is then i n serted ove r the d i l ator a n d g u id e wi re, a n d the tracheostomy tube a n d d i l ator a re adva nced as a u n it i nto the trachea. (H) The d i l ator i s then rem oved l eavi n g the tra c heostomy t u be i n situ. ( I ) The cuff of the tracheostomy t u be i s i nfl ated a n d con n ected to the ve nti l ator. (Pa rt F, provided with perm ission fro m Cook Critica l Ca re, B l o o m i ngton, I N)

and Ripamonti.35 With this technique, a guide wire is inserted cephalad into the tracheal space and pulled out through the mouth. A trocar and tracheostomy rube with a pointed tip is then advanced over the wire and with traction applied to the guidewire, the trochar-tracheostomy rube assembly is advanced through the mouth into the trachea. A pretracheal incision is then made over the skin so that the trocar end of the tracheostomy rube can be delivered through the anterior neck. The trocar is then cut away leaving the tracheostomy rube in place. This technique avoids the downward direction of dilation and rhus may minimize damage to the posterior tracheal wall. 23 A fourth method uses a single dilator from the Percutwist'M Tracheostomy Dilator Set (Rilsch, Kernen, Germany) . This procedure uses a Seldinger technique in which a hydrophilically coated PercurwistTM dilator is moistened and advanced over a guide wire with a twisting motion to enlarge an opening in the anterior tracheal wall. A 9. 0-mm internal diameter (ID) tracheostomy rube is fitted with the insertion

dilator and subsequently advanced over the guidewire into the trachea.36 The PercurwistTM has had a higher rate of posterior wall puncture than the Ciaglia Blue Rhino technique.37 The newest technique is a modification of the Ciaglia single-dilator technique that involves balloon dilation38 but this was found to require more time and be more difficult to perform when compared to the Ciaglia single-dilator technique.39 Two meta­ analyses have been performed to analyze randomized con­ trol studies comparing different PDT techniques in patients requiring long-term ventilation. The first meta-analysis con­ cluded that the original Ciaglia multiple-dilator and Ciaglia single-dilator techniques were the best available, followed by the Griggs technique.40 However they concluded the num­ ber of available trials was insufficient to definitely conclude which PDT technique was the best. The second meta-analysis concluded that the Ciaglia single-dilator method was less dif­ ficult but also that surgeons had more experience with this technique.41

Perfo rm i n g a n E l ective Perc uta neous D i lati o n a l Trac h eotomy i n a Pati ent on Mec h a n ica l Ve ntilation

F I G U R E 3 3 - 3 . Trac h eostomy tu bes: (A) Bivo n a Foa m-Cuf s i l icone t u be (Bivo n a Med ica l Tec h n ol og ies, Ga ry, I N), (B) S h i ley cuffed n o n ­ fenestrated tu be, (C) S h i ley cuffed fe nestrated tu be, (D) S h i ley u n c uffed fe nestrated t u be (S h i l ey M a l l i n c krodt, S t . Lou i s, MO).

• Describe and Compare Different

Tracheostomy Tubes. Which Tube Would You Choose for Th is Patient?

In selecting a tracheostomy tube, patient anatomy and ven­ tilatory needs must be considered. These needs will influence choice of tube ID, length, cuff design, use of an inner cannula, and presence or absence of fenestrations. Sizing usually refers to the ID. The smallest outer diameter that satisfies the require­ ment for ventilation should be chosen . 1 8 Optimal sizing should aim for a tracheostomy tube approximately three-quarters of the diameter of the tracheal lumen. In our case presentation, the indication for tracheotomy is prolonged intubation and ventilation, so a cuffed tube which seals the airway and prevents loss of tidal volume would be a good selection. One example of such a cannula is the No. 6 (6.0-mm ID) Shiley (Mallinckrodt, St. Louis, MO) with a large-volume, low-pressure, air-filled cuff (Figure 33-3B) . 1 8 It is important to maintain an inflated cuff pressure of less than 30 em H 0 to prevent tracheal mucosal ischemia and mini­ 2 mize the risk of erosion. Once the patient is weaned from the ventilator, conversion to a fenestrated tube (Figure 33-3C) might be appropriate because it reduces work of breathing and enables vocalization. 18 Another option is to downsize the non-fenestrated tracheostomy tube which would also permit the patient to vocalize, while minimizing the risk of granula­ tion tissue formation at the site of the fenestration. Excessive granulation tissue can cause tracheostomy tube obstruction and may also produce impressive bleeding from the airway. But, in general, the choice of a tracheostomy tube is often based on the practitioner's individual experience and preference. Special consideration must be given to the obese patient. Standard tracheostomy tubes are unlikely to conform to the anatomy and thus a better choice is a flexible tube which is extra long and adjustable, 18 such as Bivona (Bivona Medical Technologies, Gary, IN) or Tracoe (TRACOE medical GmbH, Frankfurt, Germany) tracheostomy tubes. The disadvantage of

these tubes is that they have a single lumen without an inner cannula. They do have an advantage of minimizing risks of an inappropriately fitted tube, such as tube obstruction if too short, or necrosis of the anterior tracheal wall if too long. • What Are the Advantages of Perform ing PDT

Over ST?

In general, the complications of PDT are few and are compa­ rable to ST.42 Theoretical advantages of PDT include a smaller skin incision, less dissection and tissue trauma which leads to less hemorrhage, fewer infections, fewer tracheal problems, and fewer cosmetic deformities. In addition, the procedure can be performed at the bedside in the ICU, by nonsurgical personnel, decreasing the risks inherent in patient transport to the oper­ ating room, as well as less overall cost and less use of human resources. 1 7· 24,43 The disadvantages of performing PDT in the ICU relate mainly to lack of proper facilities and equipment. Poor lighting conditions and a crowded environment can also be hazardous. These risks can be minimized by proper prepara­ tion of a surgical set that includes drapes, tracheostomy tubes of various sizes, portable electrocautery, and a surgical lamp. A difficult airway cart should also be immediately available, as should appropriate anesthetic drugs, including skeletal muscle relaxants.

COMPLICATIONS • What Are the Contra indications to

Perform ing a PDT?

Physiologic contraindications to PDT include a patient who is hemodynamically unstable, requires an Fi0 > 0. 60, PEEP 2 > 1 0 em H 0/ or has an uncontrolled coagulopathy. 3 Anatomic 2 contraindications include a previously documented difficult tracheal intubation, morbid obesity, obscure cervical anatomy, goiter, short thick neck, previous tracheotomy or neck surgery,

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Ai rway M a n a g e m e n t in the I nte n s ive Ca re U n it (ICU)

TAB L E 33-1 . Co m p l icatio n s of Trac heotomy

I ntraoperative

Postoperative ( < 24 Hours}

Up to 2 Weeks

Weeks to Months

Da m a g e to g reat vesse l s

Tu be d i s l od g e m ent with loss of a i rway

Pe risto m a l cel l u l itis

I nj u ry t o poste rior tra c h e a l wa l l I nj u ry to c u p u l a of l u n g with p n e u m othorax Tra c h e a l r i n g d a m a g e Rec u r rent l a ryngea l ne rve i nj u ry Pa ratra c h e a l i n sertion F i re i n the a i rway

Tu be occ l u si o n by d ried secret i o n s Sto m a l h e m o r r h a g e

Sto m a l g ra n u lation tissue

S u p ra sto m a l o r tra c h e a l g ra n u lation tissue with a i rway o bstruction Poor sto m a l h ea l i n g

Sto m a l h e m o r r h a g e

Cuff l e a k

S u bg l ottic or tra c h e a l ste n o s i s Tra c h e o m a l a c i a Trach eoeso p h a g e a l fi st u l a Tracheoi n n o m i nate fi st u l a

Data fro m Refs. 3, 7, a n d 1 8 .

cervical infection, facial and cervical trauma and fractures, halo traction, or known presence ofSGS.3 , 7 However, PDT has been successfully performed in the morbidly obese and in those who had a previous tracheotomy.44 • What Are the Compl ications of PDT

versus ST?

Complications common to both PDT and ST are listed in Table 33- 1 and are summarized in a review by Engels et al.45 At least four meta-analyses have been published comparing PDT to ST. Delaney et al.46 identified 17 randomized control trials with 1 2 1 2 patients and concluded that PDT resulted in significantly fewer infections compared to ST. In a pooled data analysis with 973 patients from 1 5 randomized control trials, Higgins and Punthakee also found that PDT had fewer wound infections, as well as less scarring and lower costs than ST. This difference was lost when only bedside procedures were con­ sidered. Of note, PDT did result in more decannulation and obstruction problems than ST.47 Oliver et al.48 analyzed 14 pro­ spective and randomized controlled studies with 1 273 patients and showed more early and minor complications with PDT than with bedside ST, but no difference in late complications. A more recent meta-analysis which included eight randomized controlled trials with pooled data comparing the Ciaglia multi­ ple-dilator and single-dilator PDT techniques to ST found that PDT could be performed faster and with less stomal inflam­ mation but that there was no difference in patient outcomes.49

POST-TRACH EOTOMY MANAGEM ENT • What Should be Done Immediately After the

Placement of a PDT?

Following insertion of the tracheostomy tube, one must ensure that the tube is properly positioned and well secured until the tract has healed, in approximately 7 days. Because PDT is a dilational technique, creation of a false passage may easily occur.

Should accidental decannulation occur within the first 7 days of PDT, and if a tracheal tube is needed, an oral ETT should be immediately placed instead of attempting reinsertion of a tracheostomy tube through the stoma. 5° Chest x-ray following the procedure is somewhat controversial: studies have shown that the incidence of pneumothorax following endoscopically guided PDT is less than 3%, although when non-guided, it may range up to 1 2%? However, since there are no strong pro­ spective data available, recommendations to exclude a routine chest x-ray cannot be made at the present moment.

• Discuss the Special Care of a Tracheostomy

Tube

Surgical cannulation of the trachea will cause an increase in secretion production requiring frequent suctioning.50 The suc­ tion catheter should be measured such that suctioning beyond the tip of the tracheostomy tube is not performed. If this simple measure is followed, then subsequent risks of deep suctioning will be eliminated. The potential trauma from deep suctioning includes tracheal excoriation, bleeding, ulceration and trache­ itis, production of granulation tissue, and scarring of the bron­ chi and carina. Creation of a tracheotomy bypasses the nose so supple­ mental humidity and filtering of the air must be provided.50 Humidity, in conj unction with tracheal irrigation, will help prevent encrusting of tracheal secretions and minimize mucus plugging of the tracheostomy tube. A filter may be placed on the tracheostomy tube to remove particulate matter in the air and from the ventilator. The first tracheostomy tube change should be done once the tract is sufficiently mature to minimize the risk of creating a false passage. The timing varies with each center. But, it is gener­ ally done 5 to 7 days after an ST. 5 2 However, in our institution, the first tracheostomy tube change is done as early as 3 days. The first change after a PDT is usually at 7 days as the initial stoma is smaller and only created by a puncture and tissue dilation.

Perfo rm i n g a n E l ective Perc uta neous D i lati o n a l Trac h eotomy i n a Pati ent on Mec h a n ica l Ve ntilation

SPECIAL CON S I D E RATIONS • Should PDT be Performed in the Ped iatric

Population?

Traditionally PDT is not recommended for individuals younger than 1 6 years of age, the main drawbacks being the small air­ way diameter and the pronounced pliability of the cartilaginous framework. Fantoni and Ripamonti53 have tried three different techniques in the pediatric population, one of which consisted of PDT guided by rigid bronchoscopy. This eliminated the main cartilaginous compliance issue seen in the pediatric population and elevated the trachea to a more superficial position, enabling cannulation. Ultimately, any technique used in the pediatric population should be performed in the operating room with specialized surgical staff and anesthesia support. Although the percutaneous dilational technique is still considered experimen­ tal in the pediatric patient population, in experienced hands and with the use of a rigid bronchoscope, an overall reduction in complications has been noted. These include smaller opera­ tive incisions in the skin and trachea, less blood loss, and virtual elimination of pleural dome injury and posterior wall trauma. 53 • Can You Perform a PDT in a

Patient with SGS?

SGS is a known late complication of prolonged intubation or any type of tracheotomy. However, little has been published on the use of PDT in a patient with SGS. SGS is a graded problem, ranging from mild asymptomatic stenosis to complete obstruction. If the stenosis exceeds 50% to 75% of the lumen diameter, then the patient may be quite symptomatic, possibly requiring acute airway intervention. In known cases of SGS, optimal airway control may be achieved with an extra-long, small, non-cuffed pediatric ETT, or more likely a controlled tracheotomy performed in an awake patient or over a rigid bronchoscope. It would be most imprudent to undertake PDT in the face of SGS as the vertical length, or thickness, of the stenosis may not be known even if the diameter is not significantly narrowed. To maximize patient safety and minimize otherwise preventable complications from PDT, this technique should not be used in a patient with known SGS. • What Is the Role of an Extraglottic Device

in Providing Oxygenation and Ventilation While Performing the PDT?

To avoid the potential problem of an inadvertent puncture of the ETT cuff by the needle, tube transfixion, or accidental extubation, some reports suggest replacing the in situ ETT with an extraglottic device (EGD) shortly prior to the placement of the PDT. The laryngeal mask airway (LMA) , intubating LMA, LMA-ProSeal, CobraPLA, Airway Management Device (AMDTM) , and the Combitube have all been used successfully during PDT placement during the last decade.54-60 While EGDs may have a theoretical advantage over the ETT in ventilating critically ill patients during PDT, they also have limitations, including difficult placement. In a prospective

comparative study of PDT performed on patients with either an ETT or an LMA in situ, Ambesh et al.61 showed that 33% of patients with LMAs during the PDT suffered potentially catastrophic complications. These included loss of the airway, inadequate ventilation with hypoxemia, gastric distension, and regurgitation. In contrast, there were substantially fewer com­ plications in the ETT group. Until more clinical efficacy and safety data are available on the use of EGDs during PDT, in our opinion, the in situ ETT remains the best option during the procedure. In these critically ill patients who may have low lung compliance, airway edema, cervical spine instability, or a difficult airway, the ETT will pro­ vide a more secure airway during PDT. However, in the event that the airway is lost or accidental extubation occurs, EGDs may play an important role in oxygenating the patient while completing the PDT.

S U M MARY To minimize airway complications, tracheotomy is often nec­ essary for long-term mechanically ventilated patients in the intensive care setting. During the last two decades, elective PDT has been shown to be an effective and safe alternative to traditional ST. Theoretical advantages of PDT over ST include a smaller skin incision, less dissection, less tissue trauma, less hemorrhage, fewer infections, fewer tracheal problems, and less cosmetic deformity. In addition, the procedure can be per­ formed at the bedside by nonsurgical personnel, decreasing the inherent risks of transporting patients to the operating room. However, practitioners should also be aware of the limitations and disadvantages of performing PDT in the intensive care unit. These include a lack of proper facilities and equipment, poor lighting conditions, and a crowded environment.

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Ai rway M a n a g e m e n t in the I nte n s ive Ca re U n it (ICU) 1 2 . Coonan TJ, Hope CE, Howes WJ, Holness RO, Macinnis EL. Ankylosis of the temporo-mandibular joint after temporal craniotomy: a cause of difficult intubation. Can Anaesth Soc}. 1 98 5 ;32(2): 1 5 8- 1 60. 1 3 . Francois B, Clave! M, Desachy A, Puyraud S, Roustan J, Vignon P. Complications of tracheostomy performed in the ICU: subthyroid trache­ ostomy vs surgical cricothyroidotomy. Chest. 2003; 1 2 3 ( 1 ) : 1 5 1 - 1 5 8 . 14. Talving P. DuBose J, lnaba K , Demetriades D. Conversion of emer­ gent cricothyrotomy to tracheotomy in trauma patients. Arch Surg. 2 0 1 0; 1 4 5 ( 1 ) : 87 -9 1 . 1 5 . Dillon JK, Christensen B , Fairbanks T, Jurkovich G , Moe KS. The emer­ gent surgical airway: cricothyrotomy vs. tracheotomy. Int} Oral Maxillofoc Surg. 20 1 3 ;42(2) :204-208 . 1 6. Bowen C P. Whitney LR, TruwitJD, Durbin C G , Moore M M . Comparison of safety and cost of percutaneous versus surgical tracheostomy. Am Surg. 200 1 ;67( 1 ) : 54-60. 1 7. Dulguerov P, Gysin C, Perneger TV, Chevrolet J C. Percutaneous or surgi­ cal tracheostomy: a meta-analysis. Crit Care Med. 1 999;27(8) : 1 6 1 7- 1 625. 18. Walts PA, Murthy SC, DeCamp MM. Techniques of surgical tracheos­ tomy. Clin Chest Med. 2003;24(3) : 4 1 3-422. 1 9. Shelden CH, Pudenz RH, Freshwater DB, Crue BL. A new method for tracheotomy. J Neurosurg. 1 95 5 ; 1 2 (4) :428-43 1 . 20. Powell DM, Price PD, Forrest LA. Review of percutaneous tracheostomy. Laryngoscope. 1 998; 1 08 (2) : 1 70- 1 77. 2 1 . Toye FJ, Weinstein JD. Clinical experience with percutaneous tracheostomy and cricothyroidotomy in 1 00 patients. } Trauma. 1 986;26 ( 1 1 ) : 1 034- 1 040. 22. Ciaglia P, Firsching R, Syniec C. Elective percutaneous dilatational tra­ cheostomy. A new simple bedside procedure; preliminary report. Chest. 1 985 ;87(6) : 7 1 5-7 1 9. 23. deBoisblanc BP. Percutaneous dilational tracheostomy techniques. Clin Chest Med. 2003;24(3) :399-407. 24. Ciaglia P, Graniero KD. Percutaneous dilatational tracheostomy. Results and long-term follow-up. Chest. 1 992; 1 0 1 (2) :464-467. 25. Schwann NM. Percutaneous dilational tracheostomy: anesthetic consider­ ations for a growing trend. Anesth Analg. 1 997;84(4) : 907-9 1 1 . 26. Paul A, Marelli D, Chiu RC, Vestweber KH, Mulder DS. Percutaneous endoscopic tracheostomy. Ann Thorac Surg. 1 989;47(2) : 3 14-3 1 5 . 27. Al-Ansari MA, Hijazi MH. Clinical review: percutaneous dilatational tra­ cheostomy. Crit Care. 2006; 1 0 ( 1 ) :202. [Epub December 1 7, 2005] . 28. Kollig E, Heydenreich U, Roetman B, Hopf F, Muhr G. Ultrasound and bronchoscopic controlled percutaneous tracheostomy on trauma !CU. Injury. 2000;3 1 (9) :663-668. 29. Chacko J, Gagan B, Kumar U, Mundlapudi B. Real-time ultrasound guided percutaneous dilatational tracheostomy with and without bronchoscopic control: an observational study. Minerva Anestesiol. 20 1 5; 8 1 (2) : 1 66- 1 74. 30. Alansari M, Alotair H, AI Aseri Z, Elhoseny MA. Use of ultrasound guid­ ance to improve the safety of percutaneous dilatational tracheostomy: a literature review. Crit Care. 20 1 5 ; 1 9:229. 3 1 . Mallick A, Venkatanath D, Elliot SC, Hollins T, Nanda Kumar CG. A pro­ spective randomised controlled trial of capnography vs. bronchoscopy for Blue Rhino percutaneous tracheostomy. Anaesthesia. 2003 ; 5 8 (9):864-868. 32. Addas BM, Howes WJ, Hung OR. Light-guided tracheal puncture for percutaneous tracheostomy. Can } Anaesth. 2000;47(9) :9 1 9-922. 33. Schachner A, Ovil J, Sidi J, Avram A, Levy MJ . Rapid percutaneous tra­ cheostomy. Chest. 1 990;98(5) : 1 266- 1 270. 34. Griggs WM, Worthley LI, Gilligan JE, Thomas PD, Myburg JA. A simple percutaneous tracheostomy technique. Surg Gynecol Obstet. 1 990; 1 70(6) : 543-545. 3 5 . Fantoni A, Ripamonti D. A non-derivative, non-surgical tracheostomy: the translaryngeal method. Intensive Care Med. 1 9 97;23 (4) :3 86-392. 36. Frova G, Quintel M. A new simple method for percutaneous tracheos­ tomy: controlled rotating dilation. A preliminary report. Intensive Care Med. 2002;28 (3):299-303. 37. Byhahn C, Westphal K, Meininger D, et a!. Single-dilator percutaneous tracheostomy: a comparison of PercuTwist and Ciaglia Blue Rhino tech­ niques. Intensive Care Med. 2002;28 (9) : 1 262- 1 266. 38. Zgoda MA, Berger R. Balloon-facilitated percutaneous dilational trache­ ostomy tube placement: preliminary report of a novel technique. Chest. 2005; 1 28(5) :3688-3690. 39. Cianchi G, Zagli G, Bonizzoli M, et a!. Comparison between single-step and balloon dilatational tracheostomy in intensive care unit: a single­ centre, randomized controlled study. Br J Anaesth. 20 1 0; 1 04(6) : 728-732. 40. Cabrini L, Monti G, Landoni G, et a!. Percutaneous tracheostomy, a sys­ tematic review. Acta Anaesthesiol Scand. 20 1 2;56(3):270-28 1 . 4 1 . Sanabria A. Which percutaneous tracheostomy method is better? A sys­ tematic review. Respir Care. 20 1 4 ; 5 9 ( 1 1 ) : 1 660- 1 670. 42. Feller-Kopman D. Acute complications of artificial airways. Clin Chest Med. 2003;24 (3) :445-45 5 .

4 3 . Freeman B D , Isabella K , Lin N, Buchman TG. A meta-analysis of prospec­ tive trials comparing percutaneous and surgical tracheostomy in critically ill patients. Chest. 2000; 1 1 8 (5) : 1 4 1 2- 1 4 1 8. 44. Ernst A, Critchlow ]. Percutaneous tracheostomy-special considerations. Clin Chest Med. 2003;24 (3) :409-4 1 2 . 45. Engels PT, Bagshaw S M , Meier M, Brindley P G . Tracheostomy: from insertion to decannulation. Can } Surg. 2009;52(5):427-433. 46. Delaney A, Bagshaw SM, Nalos M. Percutaneous dilatational tracheos­ tomy versus surgical tracheostomy in critically ill patients: a systematic review and meta-analysis. Crit Care. 2006; 1 0 (2):R5 5 . 4 7 . Higgins KM, Punthakee X . Meta-analysis comparison of open versus per­ cutaneous tracheostomy. Laryngoscope. 2007; 1 1 7(3) :447-454. 48. Oliver ER, Gist A, Gillespie MB. Percutaneous versus surgical tracheot­ omy: an updated meta-analysis. Laryngoscope. 2007; 1 1 7(9) : 1 570- 1 575. 49. Putensen C, Theuerkauf N, Guenther U, Vargas M, Pelosi P. Percutaneous and surgical tracheostomy in critically ill adult patients: a meta-analysis. Crit Care. 20 1 4; 1 8 (6): 544. 50. Wright SE, VanDahm K. Long-term care of the tracheostomy patient. Clin Chest Med. 2003;24(3) :473-487. 5 1 . Gonzalez I, Bonner S . Routine chest radiographs after endoscopically guided percutaneous dilatational tracheostomy. Chest. 2004; 1 2 5 (3): 1 1 73- 1 1 74. 52. Tabaee A, Lando T, Rickert S, Stewart MG, Kuhel WI . Practice patterns, safety, and rationale for tracheostomy rube changes: a survey of otolaryn­ gology training programs. Laryngoscope. 2007; 1 1 7(4) : 5 73-576. 53. Fantoni A, Ripamonti D. Tracheostomy in pediatrics patients. Minerva Anestesiol. 2002;68(5) :433-442. 54. Dexter T]. The laryngeal mask airway: a method to improve visualisation of the trachea and larynx during fibreoptic assisted percutaneous tracheos­ tomy. Anaesth Intensive Care. 1 994;22 ( 1 ) : 35-39. 55. Lyons BJ, Flynn CG. The laryngeal mask simplifies airway management during percutaneous dilational tracheostomy. Acta Anaesthesiol Scand. 1 995;39(3) : 4 1 4-4 1 5 . 56. Verghese C, Rangasami ], Kapila A, Parke T. Airway control during percu­ taneous dilatational tracheostomy: pilot study with the intubating laryn­ geal mask airway. Br J Anaesth. 1 998; 8 1 (4) :608-609. 57. Craven RM, Laver SR, Cook TM, Nolan JP. Use of the Pro-Seal LMA facilitates percutaneous dilatational tracheostomy. Can J Anaesth. 2003;50(7) : 7 1 8-720. 58. Agro F, Carassiti M, Magnani C. Percutaneous dilatational cricothyroid­ otomy: airway control via CobraPLA. Anesth Ana/g. 2004;99 (2) :628. 59. Johnson R, Bailie R. Airway management device (AMD) for air­ way control in percutaneous dilatational tracheostomy. Anaesthesia. 2000; 5 5 (6) : 596-597. 60. Mallick A, Quinn AC, Bodenham AR, Vucevic M. Use of the Combirube for airway maintenance during percutaneous dilatational tracheostomy. Anaesthesia. 1 998;53(3):249-25 5 . 6 1 . Ambesh SP, Sinha PK, Tripathi M, Matreja P. Laryngeal mask airway vs endotracheal tube to facilitate bedside percutaneous tracheostomy in critically ill patients: a prospective comparative study. J Postgrad Med. 2002;48 ( 1 ) : 1 1 - 1 5 .

SELF - EVALUATION QU ESTIONS 3 3 . 1 . You are a n airway practitioner and have been asked to participate in a PDT on the 28-year-old female in the ICU. The surgeon has j ust inserted the tracheostomy tube and you are ventilating the patient using an Ambu bag through the ETT that you have pulled back to 1 em above the tracheotomy insertion site. Once the trache­ ostomy tube is in place, you connect the Ambu bag to the tracheostomy tube and start to ventilate the patient. However, you notice that there is no end-tidal C0 trac­ 2 ing and there is a lot of resistance to ventilation, the oxygen saturation is slowly declining, and there is some subcutaneous emphysema in the neck area. What is your immediate response? A. remove the tracheostomy tube and the ETT and begin BMV B. tell the surgeon to reinsert the tracheostomy tube

Perfo rm i n g a n E l ective Perc uta neous D i lati o n a l Trac h eotomy i n a Pati ent on Mec h a n ica l Ve ntilation

C. tell the surgeon cricothyroidotomy

to

prepare

for

a

surgical

D. remove the tracheostomy tube and push the indwell­ ing ETT into the trachea 2 to 4 em distally and ven­ tilate through the ETT E. assess the location of the tracheostomy tube using a fiberoptic bronchoscope 33.2. You have secured the airway and placed the patient back on the ventilator. About 5 minutes later while you are catching up on your charting, the ventilator starts to alarm high airway pressures and the blood pressure has declined. Auscultation reveals decreased breath sounds on the right. What do you do next? A. administer 500 mL of Ringers Lactate intrave­ nously and vasopressor to raise the propofol-induced hypotension B. call for a chest x-ray

C. fiberoptic bronchoscopy to remove mucus plugs D. do a needle decompression in the midclavicular line at the right second intercostal space of the chest or insertion of a chest tube 3 3 . 3 . Three days after the PDT was performed, as an anes­ thesiologist you are called urgently to the ICU because the tracheostomy tube was decannulated and despite attempts at BMV, the patient's oxygen saturation is 80%. Which of the following should you avoid? A. attempt BMV with two operators B. insert an LMA C. insert a Combitube D. insert an ETT orally E. reinsert the tracheostomy tube

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C H A PT E R 3 4

Manage ment of a Patient with a Res piratory Arrest in the Intermediate Care Unit Peter G. Brindley

CAS E PRESENTATION

400

I NTRO DUCTION .

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I M P ROVI NG COM M U N I CATION ARO U N D T H E D I F F I C U LT A N D FAI LE D AI RWAY

40 1

S U M MARY . . . . . . . . . . . .

404

SELF-EVALUATIO N Q U ESTI O N S . . . . . . . . . . . . . . . . . . . 405

CASE PRESENTATION A respiratory arrest occurs in the intermediate care unit on the sur­ gical ward. The patient is an elderly man in a cervical halo, 3 days after admission and following a motor vehicle crash. Soon after a "code-blue" is called overhead to which both the intensive care unit (ICU) resident and the anesthesia resident respond. Upon arrival, a large number of other health care providers are crowded into the room, including many medical students who were receiv­ ing a lecture nearby. The noise level is high, and it is impossible to hear anyone calling out instructions. It is also impossible to tell if someone is leading the resuscitation or preparing for intubation. Two nurses are taking turns performing chest compressions and a respiratory therapist is performing appropriately slow bag-mask-ventilation. The anesthesia resident goes to the head of the bed. He starts making suggestions: "perhaps we could intubate"; "maybe it's time for others to take over compres­ sions"; and "I think someone needs to lead this resuscitation." Unfortunately, nobody picks up on his initial polite hints. As such, he believes he has tried but there is no point try­ ing again. He subsequently becomes silent, and stands at the

head of the bed silently hoping somebody will hand him a laryngoscope and an endotracheal tube. The ICU resident goes to the patient's right groin to insert a central line and shouts for "someone," "anyone" to get him "the damn equipment." He is angry when nobody does and starts berating the others for being "lousy teammates." A surgical resident arrives at this point and asks if the patient might have a postoperative pulmonary embolus and whether there are contraindications to thrombolysis. He announces that if the patient survives they ought to get "a 12-lead ECG and a bedside echo," and then he walks away. Meanwhile the nurses performing chest compressions have become exhausted but do not know how to ask for relief As such they cease compressions and it is 30 seconds before another person takes over. The anesthesia resident uses this pause in chest compressions to attempt tracheal intubation, but fails. He does not know if anyone has airway skills, so he tries four more times before causing airway bleeding and hence returns to bag-mask-ventila­ tion. The patient has been without a pulse now for 45 minutes. A nurse suggests calling the ICU attending physician. She arrives and finds a Do-Not-Resuscitate order on the chart. At this point resuscitative efforts are ceased and the patient is declared dead. While several of the team members try to leave stating: "well, he was a DNR so it doesn't matter," the attending/ consultant insists they remain for an immediate debrief She states that the crisis management skills, and especially the com­ munication skills need to be improved. They agree, but when they request specifics, the intensivist is unsure what to say.

I NTRODUCTION • Why Ded icate a Chapter to Commun ication

Skills in the Difficult and Failed Airway?

The above case includes several clinical errors. However, as cor­ rectly pointed out by the attending intensivist, the crisis man­ agement skills, and especially the communication, were especially

M a n a g e m e n t of a Patient with a Res p i ratory Arrest i n the I nte rmed iate Ca re U n it

poor. In another high-stakes industry, namely aviation, pilots can summarize their job as: "navigate, aviate, and communi­ cate." 1 Pilots could also argue that they "fly by voice." All of these suggest that planes are flown as much by communication as by the plane's controls and instruments. 1 '4 Accordingly, air­ way practitioners managing difficult and failed airways should perhaps learn to "oxygenate; ventilate; communicate" and to "resuscitate by voice." 2 •3 This is because of all the human factor and crisis management skills, the most important appears to be communication. 2'6 This chapter supplements the discussion of human factors and teamwork outlined in Chapter 6. This is because if com­ munication means to "share, join, unite, or make understand­ ing common," 2 then, much of what it means to create a good airway team, or is to become a good team communicator. 2-4 However, j ust as teamwork does not come naturally nor does communication in crisis situations. 2-15 For these reasons, this chapter will focus on practical communication skills that can be applied to the difficult and failed airway. Readers are strongly encouraged to read widely given the importance of this topic. They should also accept that being an expert airway practitioner includes being an expert communicator. 2-4 Many of the ideas contained within this chapter are not native to medicine (or to this author) . Instead, as in Chapter 6, these ideas have been translated from other high-consequence low-tolerance professions; most notably aviation. As previously stated, we should not overdo the comparison between aviation and acute care medicine. After all, whereas planes may not take off during significantly inclement weather, the failed airway forces practitioners to routinely "fly into the storm." However, poor cockpit communication-especially between junior and senior crew-has long been understood to be one of the com­ monest reasons why mechanically sound planes crash. 3-5 This is mirrored in acute medical crisis (such as the difficult and failed airway) where poor communication is one of the commonest reasons for preventable medical error and preventable death.3-9 The difference is that medicine has only recently embraced deliberate communication instruction. This chapter is part of a long overdue catch up, and an effort to move beyond terror or hubris when it comes to the difficult and failed airway.

I M P ROVI NG COM M U N I CATION AROU N D T H E D I F F I C U LT A N D FAI L E D AI RWAY • What Are the Basics of Commun ication

facial expressions, gestures, and eye contact) , as well as paraver­ bal communication (which includes pacing, tone, volume, and emphasis) are at least as important as verbal communication. 2 •3 Understanding communication as verbal, paraverbal, and nonverbal is especially important if there is incongruence between the words used and the facial expression or the tone. 2'4 For example, if we say: "I don't need your help with this intu­ bation" but in a tone that suggests otherwise then listeners are likely to downplay the verbal in favor of the nonverbal. Alternatively, they may base their response upon prior interac­ tions (i.e. , "he never wants help from anyone . . . no matter what he says") . As such, we need to "say what we mean and mean what we say." At best, incongruence can increase mis­ interpretation, at worst it erodes teamwork. 2-4 Congruence is even more important when those involved are unfamiliar, or when the medical situation is novel. 2-4 In addition, practitioners should understand that we really cannot afford to not commu­ nicate. Failing to say anything can also send its own unintended message. For example, silence can be variously misinterpreted as lack of concern, unwillingness to work with others or assent. Aviation made flattening the authority-gradient a prior­ ity.5 A practical strategy is to teach and model more "hori­ zontal communication." 2-3 This means that all members of the team are authorized-in fact obligated-to speak up, and to do so clearly, regardless of rank.5 Moreover, aviation has mandated "transmitter-orientated" communication (where it is the speaker's responsibility to be understood) , rather than "receiver-orientated" communication (where it is the listener's responsibility to unravel what was meant) .5 However, making communication more deliberate means that we also promote active listening. 2 This requires that we confirm understanding and demand clarification, regardless of seniority or embarrass­ ment. All team members take responsibility for how messages are delivered, received, understood, and carried out. 2-5·8 If we compare communication to a drug, it would be under­ stood to be one of our most potent "therapies." Similarly, like a drug, communication is not one-size-fits-all, nor a panacea. Like a drug, it should be used in the right dosage at the right time and tailored to the patient's needs. Like a drug, communication can also be either a "placebo" (i.e., good communication makes things better) or "nocebo" (i.e., bad communication makes things worse) . 2-3 Better communication might also decrease litigation and maintain a hospital's reputation. Regardless, communication is everybody's business: it should be taught to trainees, expected from practitioners, and supported by administration. 2-4· 1 1

Success and Com m u n ication Error?

Our communication shortfalls can be neatly summarized using a quote from Rall and Gaba6: "Meant is not said; said is not heard; heard is not understood; understood is not done." However, it is also important not to oversimplifY something as complex as communication. The first insight is that com­ munication is more than j ust talking. Good communication is a key therapy that aids (or impairs) task execution, bolsters (or stalls) information exchange, and helps (or hinders) relation­ ship building. 2-4 Communication is also more than just what is said. It also includes how it is said and how it is understood. 2 As a result, nonverbal communication (which includes posture,

• What Are Some Relevant Com munication

Models, and How Could They be Adapted to the Difficult and Failed Airway?

Shannon and Weaver, working for Bell Laboratories, developed a model for verbal telephone communication. It can still be applied to medicine, decades on. 2 Simply put, transmitters (i.e., speakers) encode messages, and receivers (i.e., listeners) decode them. However, both must be on the same channel (which in medicine could mean possessing similar situational awareness and emotional states) , and there should be minimal interference

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(which in airway management could mean minimizing chaos, stress, or cognitive bias) . They also identified the danger of "channel-overload" (which in airway management warns against communication that is unnecessarily complex) . Overload, which often results in indecision, also occurs unless the receiver can filter data into usable information. The practical point is that a skilled practitioner will receive data ("his oxygen satura­ tion is dropping despite bag-mask-ventilation"), but be able to turn this into usable information ("we have a failed airway") . 2 Shannon's communication model has limitations. For example, complex communication also requires meaning (i.e., "we need to do a surgical airway") . Meaning is harder to encode, transmit, and decode, which is why we cannot assume that coworkers have reached the same conclusions as us. 2 Shannon's model also describes communication as uni­ directional (transmitter to receiver) , while medical decision­ making is commonly multidirectional, across disciplines and across hierarchies. 2-4' 1 1 Location (i.e., a noisy operating theater or trauma bay) ought not to affect data transmission, but it does affect communication quality, impact, and efficiency. For example, when transmitter and receiver are no longer face-to­ face our communication loses important nonverbal cues. 2 This is why communication while wearing masks is important to practice. It is also why confirming understanding by routinely summarizing and repeating back is an important fail-safe. 2-4•1 1 Newer communication models focus o n relationships, not just tasks. The "four mouths and four ears model" 2 has sender and listener separated by a message with four equal sides: (i) content; (ii) relationship; (iii) self-revelation; and (iv) appeal. Content refers to facts and words. The relationship aspect means that senders reveal (consciously and unconsciously) how they regard receivers through specific words, intonations, and non­ verbal signals. Senders also indicate how they feel about them­ selves, namely a "self-revelation." Fourth, there is an appeal (or request) where messages encourage the receiver to do (or not do) something. These four aspects apply to both talker and lis­ tener, namely we "speak with four mouths" and "listen with four set of ears." This is often unconscious, and depends on mental state, expectation, and previous interactions. 2 Notably the sender cannot fully force the listener's mind (and vice versa) . A practical example from airway management follows. When one anesthesia practitioner says to another: "What do you want me to do?" they may presume they asked an unam­ biguous question and respected the listener's knowledge and abilities. Perhaps he/she did, but intonation can suggest oth­ erwise. For example, he may also have revealed his inability to make difficult decisions or even frustration about the patient's condition ("he's too sick for me; I don't know what to do!") . Also, the clinician's self-revelation could be one of either appro­ priate patient concern or resignation ("I don't have the time/ training/authority for this airway . . . j ust tell me and I'll do it") . His request or appeal (albeit unstated) might be to try to sub­ tly persuade the second anesthesia practitioner to assume con­ trol (i.e., "''m outside of my comfort zone, what do you want me to do?") . In contrast, senior clinicians may be reluctant to either seek help or give up control. In this case, communication should unequivocally state what each person will do (i.e., "you

will be the intubator one; I will perform intubation attempt rwo while you prepare for an extraglottic device") . The second clinician also listens with four set of ears, and anyone can be more or less open. For example, a content-based response would respond with objectivity (i.e., "because you could not intubate, I will use an extraglottic device") . If the second clinician hears the self-revelation he/she might reply: "I am comfortable taking over, but please stay as I will need your ongoing help." If the second clinician is attuned to rela­ tionship aspects, or has previously had bad interpersonal relationships, then they may be more defensive (i.e., "why are you asking me; are you just trying to transfer the blame?") . Only rarely will the listener have the state of mind to decipher the appeal: "so what I think you're telling me is . . . . " Regardless, this model shows how communication can create a virtuous cycle that builds cooperation, or a vicious cycle that destroys it. 2-4 • How Do We Spea k U p in a Crisis?

Health care workers may not speak due to stress, overload, or uncertainty, or simply because they do not have the usable verbal expression (see Table 34- 1) . 1 2 Similarly, the aviation industry refers to pilots suffering from "helmet fire" and about black box silence for minutes before a crash. 1-3 Instead of risk­ ing silence, we can teach standardized verbal responses. An example would be: "direct laryngoscopy has failed: what is our Plan B and Plan C?". Another would be: "I am unclear what has happened; please summarize?". Other team members need verbal strategies to rapidly become part of the team. A simple example could be "I am from anesthesia; how can I help?". Over time, familiar lines also offer more than those few words suggest. For example, the explicit statement: "can't intubate, can't oxygenate" also implicitly states far more than those words alone. It should trigger the team to "get help"; "get the difficult airway cart"; and also that "we have permission to perform a surgical airway." When team members are familiar, or the situation is rou­ tine, then implicit communication (i.e., using minimal words, and assuming everyone knows their role) can be perfectly

TA B L E 34- 1 .

Practica l Strategies to I m prove Verba l Com m u n ication i n the Difficult a n d Fa i l ed Ai rway

Pe rfo r m reg u l a r a i rway s i m u lation exe rc i ses with a l l tea m m e m bers Practice a ctive l i ste n i n g M o d e l "tra n s m itte r-orie nted l a n g u a g e" Ban " m i t i g a t i n g l a n g u a g e" 3 Cs: cite n a m es; be c l e a r/co n c i se; c l ose the loop Stru ctu re com m u n ication u s i n g "SBAR" a n d "re peat-backs" "Ca l l out '' w h e n s i g n ificant c h a nges occ u r Practice "esca lati ng assertiven ess" Avo i d "so m e body"/"a nybody" co m m ents Res pect co m m u n i cation "ste r i l ity"; contro l i nterru pti o n s

M a n a g e m e n t of a Patient with a Res p i ratory Arrest i n the I nte rmed iate Ca re U n it

acceptable. The prime example is the formula-one pit crew whose only job is to change tires: a task that they have prac­ ticed in the same team structure countless times. The corol­ lary is that the more immature the team, the more unfamiliar the team members, or the more the situation veers from an algorithm, the more we require explicit verbal coordination. The danger of overreliance upon implicit communication in airway management is that it assumes that health care workers with varying experience and disparate backgrounds will have common understanding. For example, as the senior anesthe­ sia practitioner you might assume that by placing a series of airway adjuncts on the patient's chest, you have adequately communicated to the entire team that you are more concerned about this airway than usual ("if Dr. X is setting up all this equipment then he must be anticipating difficulty, so I should too") . Unfortunately, however, implicit communication also fails to acknowledge the power of denial ("I don't want this airway to be difficult . . . therefore it won't be") or the heuristic bias (e.g. , "the anesthesia practitioner succeeded with direct laryngoscopy the last five times, so he will again") . As stated above, we need tools to be sure that "we say what we mean and mean what we say." This is why we need to not only recognize the difficult airway but also to declare it. Other high-tasks professions do not leave communication to chance. The military and aviation have used SBAR (Situation, Background, Assessment, Recommendation) in order to pro­ vide a recognizable structure to communication. While it can be overly formal-especially when team members are either familiar with each other or if the problem is routine-it offers a useful construct for junior staff and for unfamiliar situations.13 A simple example could be: Situation: "this is Dr. X, I need your help now"; Background: "I cannot oxygenate or ventilate this patient with facial trauma''; Assessment: "We have a failed air­ way"; Recommendation: "Bring me the surgical airway kit."3•13 Applying the "Cs of communication" means that we must cite names (to avoid diffusion of responsibility) ; that we must be clear and concise (to avoid confusion) ; and most impor­ tantly, we must close the loop (to confirm that it has been done) . 2-4•8•1 2 This last facet (namely "closing the loop") means that we reinforce (or amplify) our instructions by demanding feedback. For example, we tell a specific colleague to intubate but also to tell us when it is done (or tell us the end-tidal C0 ) . This also means we do not j ust ask a colleague to 2 increase the oxygen level but rather "John, increase to 1 00% oxygen . . . and call out the saturation every minute" or "Jim, immediately poke for an arterial blood gas . . . and bring the result back to me," or "set up a laryngeal mask airway . . . and tell me when ready." In other words, there are many ways to "close the loop," but as a strategy it confirms that the instruc­ tion was heard, understood, and done. A potential additional C includes "crowd control." This means ensuring that there are enough people present ("we do not have someone who can do a surgical airway, go and get me Dr. X") , or that we have the right people present ("can you do a surgical airway: yes or no?") , or that we do not have too many people present ("thank you for responding, but we need to clear out all but the following people . . . ") .

• How Do We Make Ou rselves Heard in a

Crisis?

In addition to getting aviators to speak up, they are taught how to be acknowledged. Therefore, they learn how to use a variety of levels or grades of assertiveness. 2-5•12 •14-16 For example, aviation's three-step model teaches C.U. S . : I'm Concerned; I'm Uncomfortable; this is a Safety issue. Aviation's four-step P.A.C.E. communication progresses from Probing to Alerting to Challenging to Emergency language. Other aviation con­ structs include up to six steps. Regardless, the intention is to offer strategies from least to most direct. For example, the six­ step approach includes the "hint" (e.g. , "should things look like this?") ; "preference" (e.g., "I would suggest. . . "); "query" (e.g. , "what do you think?"); "shared suggestion" (e.g., "you and I could"); "statement" (e.g., "we need to"); and "command" (e.g. , "do this now! " ) . Those actively listening should also pick up on the escalating urgency, and react accordingly. It is worth reemphasizing that leaders understand that crisis com­ munication is as much about listening as talking. As stated before (see Chapter 6) while leadership skills are very impor­ tant, so are good followership skills. Without instruction, junior team members may only hint (i.e.. "perhaps you would like to try something other than repeated laryngoscopy"), and, if ignored, fail to escalate their assertiveness.5 On the other extreme, without instruction, senior team members may rely too heavily upon blunt com­ mands (i.e. , "give me that laryngoscope now") .5 This style is certainly unequivocal, and is needed when team members have repeatedly failed to appreciate the seriousness of a situation. However, it can destroy the team structure if routinely used as the initial, or the only, communication style? With the same purpose in mind, aviation also teaches a five-step model of advocacy and confirmation. 1 2 The following includes aviation examples and airway corollaries: ''Attention Getter" ("Captain/ Doctor"). "State Your Concern" ("We're low on fuel/the patient is desaturating") . "State the Problem As You See It" ("I don't think we can land/I think we need to intubate now") . "State a Solution" ("Let's re-route to a closer airport/I'll get the dif­ ficult airway cart") . "Obtain Agreement" (e.g., "Okay, Captain/ Doctor?") . 1 2

• What Other Com m u n ication Strategies

Can be Applied to the Difficult and Fai led Ai rway?

Another strategy is the "call out" 1 2 where we alert the team to important changes (i.e., "he's now desaturating") . 1 5 Similarly, the "step-back method" means we force a "time-out." This com­ pels the team to reassess assumptions ("are we sure the tube went berween the cords?") . The "repeat-back method" 1 2 pro­ vides a safety check by repeating in order to confirm mutual understanding (i.e., "so is the next step extraglottic airway or surgical airway?") . The "read-back method" 1 2 means we con­ firm a verbal order before proceeding (i.e., "okay, so first you want the difficult airway cart in the room, then you want the video-laryngoscope in your left hand") .

403

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Ai rway M a n a g e m e n t i n the I nte n s ive Ca re U n it (ICU)

While team members are encouraged to speak up, contribu­ tions must be task-focused and appropriately timed. Aviation's "Sterile Cockpit Rule" means that no "nonoperational talk" is permitted during critical phases such as taxi, takeoff, or landing.3•17-18 Of note, it applies to all those in the cockpit to enforce it, not j ust those currently talking.3•17-18 This can be readily adapted to medical crises such as airway management. 2-4 For example, in less-critical situations we should confirm if oth­ ers are able to focus their attention ("I want you present during this potentially difficult airway, do you have time?"). In more critical situations we can demand attention ("Stop that con­ versation and focus on this difficult airway") . The anesthesia practitioner (or intensivist) is in his or her critical phase during induction and awakening. Therefore, others must avoid unnec­ essary noise or distraction. They should also learn not to take offense if asked to be quiet. Once the operation is underway, surgeons are in their critical phase and it is just as important for anesthesia practitioner to avoid unnecessary interruptions or disturbances. All members are responsible for creating the right environment so that the right team communication can be leveraged to benefit the patient.3•4 Ambiguous or noncommittal speech (also known as "miti­ gating speech") is common prior to airline crashes, as well as during medical crises. 5 This is why, during crises, we must replace comments like "perhaps we need to consider a surgical airway," or "we should think about an extraglottic device," with "get me the surgical airway kit now" and "if this intubation fails then we are going immediately to an extraglottic device." Junior members (or those that feel "unsafe" in their role) may mitigate speech to show deference, when embarrassed, or if unsure. 2-4 Interestingly, if time permits then "mitigating language" can be harmless, and can even aid team building (i.e., "if you get a moment could you help me with this patient?") . However, if the wrong communication tool is used during a crisis it can be j ust as dangerous as the wrong airway technique. It is about being as dexterous with your voice as with your hands. Over-cautious language is inappropriate during crises, just as overly dogmatic language can be inappropriate at less critical times. Crisis communication should still be polite, but must be unambiguous ("John, your next job is to intubate, do it now, please") . Communication must also be addressed to a specific person to avoid diffusion of responsibility.l-4.8 This is why com­ ments like "could someone?" and "does anybody?" can be as dan­ gerous as using the wrong piece of airway equipment. 2 However, just as we need to control communication during a crisis we need to loosen the reigns once it has abated. As a result, at other times we also need to promote more free-flowing communica­ tion. This is essential for debriefing conflict management, and stress relief. In other words, communication is also essential to keep the team resilient for the next difficult or failed airway. 2

S U M MARY Communication is likely the most important nontechnical skill during management of the difficult and failed airway. This is especially true in the ICU where orders (such as "give this drug now," or "get me this piece of equipment") are frequently

carried out by registered nurses while procedures (i.e., intuba­ tions, insertion of extraglottic devices) are usually performed by medical doctors. In other words, teamwork is essential, and teamwork means communication. Given its importance, "verbal dexterity" should not be assumed to be innate and nor should it be left to chance. First we need to understand that communication is more than just words: it incorporates ver­ bal, paraverbal, and nonverbal aspects. Moreover, incongruence between verbal, paraverbal, and nonverbal communication increases the likelihood of error. Fortunately practical strategies do exist and can be readily translated from other high-stakes industries and applied to the difficult and failed airway. Understanding the basics of communication may help to better manage the team and help mitigate an evolving crisis. Ultimately, though, practical strategies can be applied. These include learning and practicing standardized lines such as "can't intubate, can't oxygenate," announcing clearly when there is a dif­ ficult or failed airway and preannouncing Plan A, B, and C. Other strategies include SBAR (Situation, Background, Assessment, Recommendation) and using the three Cs (citing names, being clear and concise, and most importantly using closed-loop com­ munication) . However, in addition to speaking up, we need to ensure that our concerns are heard and acknowledged. There are practical strategies to help health care work­ ers become increasingly assertive. There is a three-step model using C.U. S . : Concerned; Uncomfortable; Safety issue, and a four-step P.A.C.E. model: Probing; Alerting; Challenging; Emergency language. A five-step model has health care work­ ers use an "Attention Getter"; then "State Your Concern"; then "State the Problem As You See It"; then "State a Solution"; and finally "Obtain Agreement." A six-step model uses the "hint"; "preference"; "query''; "shared suggestion"; "statement"; and "command" (e.g., "do this now!"). Regardless, all progress from least to most direct. Moreover, communication is not all about talking. Listeners should also recognize the escalating urgency, and react accordingly. Those charged with managing the difficult and failed airway can also use a deliberate "call out" to obtain attention, and a "repeat back" whenever there is doubt. They should also avoid mitigating or overly cautious language and could manage inter­ ruptions by translating aviation's sterile cockpit rule. The best functioning airway team also understands that crisis communi­ cation is as much about active listening as talking.

REFERENCES I . Skygod quotes. Available at: http://www.skygod.com/quotes/cliches.html. Accessed July 20 1 5 . 2. S t Pierre M, Hofinger G , Buerschaper C . Crisis Management in Acute Care

Settings: Human Factors and Team Psychology in a High Stakes Environment. New York, NY: Springer; 2008. 3 . Cyna AM, Andrew MI, Suyin GM, Tan SGM, Smith AF, eds. Handbook

of Communication in Anaesthesia and Critical Care. A Practical Guide to Exploring the Art. New York, NY: Oxford University Press; 2 0 1 1 .

4 . Brindley PG, Reynolds S F. Improving verbal communication in critical care medicine. ] Crit Care. 20 1 1 ;26: 1 5 5 - 1 59. 5 . Gladwell M. The ethnic theory of plane crashes. In: Gladwell M, ed. Outliers. New York, NY: Little, Brown and Company; 2008 : 1 77-223. 6. Rail M, Gaba D. Human performance and patient safety. In: Miller R, ed. Millers Anesthesia. Philadelphia, PA: Elsevier Churchill Livingstone, 2005:302 1 -3072.

M a n a g e m e n t of a Patient with a Res p i ratory Arrest i n the I nte rmed iate Ca re U n it 7. Aron D, Headrick L. Educating physicians prepared to improve care and safety is no accident: it requires a systematic approach. Qual Saf Health Care. 2002; 1 1 : 1 68 - 1 73 . 8. Gaba O M , Fish KJ, Howard S K . Crisis Management in Anesthesiology. New York, NY: Churchill Livingstone; 1 994. 9. Gawande A. The checklist. In: Gawande A, ed. 1he Checklist Manifosto. New York, NY: Henry Holt and Company; 2009:32-48. 1 0 . Brindley PG. Patient safety and acute care medicine: lessons for the future, insights from the past. Crit Care. 20 1 0 ; 1 4 (2) : 2 1 7-222. 1 1 . Brindley PG, Smith KE, Cardinal P, Leblanc F. Improving medical com­ munication: skills for a complex (and multilingual) world. Can Respir }. 20 1 4;2 1 :89-9 1 . 1 2 . Dunn EJ, Mills PO, Neily J, Crittenden MD, Carmack AL, Bagian JP. Medical team training: applying crew resource management in the Veterans Health Administration. }t Comm Qual Patient Saf 2007;33 (6) :3 1 7-325. 13. SBAR Institute for Healthcare Improvement. SBAR technique for com­ munication: a situational briefing model. Available at: http:/ /www.ihi. org/lHl/Topics/PatientSafety/SafetyGeneral/Tools/S BARTechniquefor CommunicationASituationalBriefingModel.htm. Accessed August 20 1 5 . 14. Leonard M, Graham S, Bonacum D. The human factor: the critical impor­ tance of effective communication in providing safe care. Qual Saf Health Care. 2004; 1 3 (suppl) :i8 5-i90. 1 5 . Fischer U, Orasanu J. Cultural diversity and crew communication. 1 999. Available at http://www.lcc.gatech. edu/� fischer/AIAA99.pdf. Accessed July 20 1 5 . 1 6. Besco RO. To intervene o r not t o intervene? Th e copilots 'catch 22': developing flight crew survival skills through the use of 'P.A.C.E'. 1 994. Available at http://www.crm-devel.org/resources/paper/PACE.pdf. Accessed July 20 1 5 . 1 7. Airbus flight operations briefing notes. Human performance: managing interruptions and distractions. Available at: http:/ /www.skybrary.aero/ bookshelf/books/1 76.pdf. Accessed July 20 1 5 . 1 8 . The Sterile Cockpit Rule Aviation Safety Reporting System (ASRS) 1 993. Available at: http://asrs.arc. nasa.gov/publications/direcrline/dl4_sterile. htm. Accessed July 20 1 5 .

SELF - EVALUATION QU ESTIONS 34. 1 . Regarding patient outcome, communication during acute medical crises

C. appears to be the most important nontechnical skill and likely the greatest determinant of teamwork and crisis management D. cannot be taught, so we need to hire innate communicators E. all of the above 34.2. The following is true about basic medical communication: A. Verbal communication is more important than para­ verbal or nonverbal communication. B . Incongruent communication occurs when verbal, paraverbal, and nonverbal communication appear to be out-of-sync. C. Communication can be understood using a three­ voices and three-ears model: words; interpretation; and meaning. D. Shannon and Weaver, two physicians, developed a communication model initially intended for doctors, but now relevant to all health care workers. E. "Silence is golden" : if you do not know what to say then just be quiet. 34.3. Which of the following is true? A. Assertiveness can be taught using models that initially came from aviation and include three, four, five, or six steps. B . The three Cs of communication stand for: Cite the priorities; Calm the team; Close the loop. C. Mitigating language is helpful in a crisis so that peo­ ple do not feel intimidated.

A. is certainly important but not as important as factual recall or manual skill

D. The "call out" and "repeat-back methods" should be avoided in a medical crisis because they create too much noise.

B. is very important outside on the wards, but far less important in the operating theater

E. Aviation's Sterile Cockpit Rule means everybody has to be quiet in case the captain needs to speak.

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C H A PT E R 3 5

Airway Manage ment of an Un cooperative Down Syn drome Patient with an U p per G l Bleed Michael F. Murphy

CAS E PRESENTATION

408

PAT I E NT EVALUATI ON

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AI RWAY EVALUATION AND MANAG EMENT O PTI O N S

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MANAG I N G TH E AI RWAY . . . . . . . . . . . . .

41 0

ADDITIONAL CO N S I D E RATI O N S . . . . . . . . . . . . . . . . . .

41 0

S U M MARY .

41 1

SELF-EVALUATIO N Q U ESTI O N S .

41 2

CASE PRESENTATION This 33-year-old white female patient with Down syndrome (DS) (Figure 35-1) presented to the gastrointestinal (GI) ser­ vice with a history of vomiting blood. You first encounter her when she is brought to the operating room (OR) at 22:00 hours with gross hematemesis and the general surgeon is going to attempt GI endoscopy to determine the site of bleeding and its cause, and attempt to stop it. Failing that, an open lapa­ rotomy is planned. As she is being transferred to the OR table, her only intrave­ nous (IV) is inadvertently pulled out. In the past, she has had repeated episodes of aspiration pneumonia felt to be related to grossly carious teeth and is scheduled for a full-mouth dental extraction in 2 weeks. On examination, she is 5 ft 2 in ( 1 57.5 em) tall and weighs 2 1 0 lb (96 kg) (BMI 38 .4) with moderate developmental delay. Vital signs are: heart rate (HR) 1 22 beats per minute (bpm) , blood pressure (BP) 1 00/80 mm Hg, and her oxygen satura­ tion on blow by oxygen is 92% (she is combative and will not

F I G U R E 35- 1 . Patient with Down syn d ro m e a d m itted to Gl ser­ vice department with a h i story of vom it i n g b l ood.

permit an oxygen mask to be applied) . You suspect that she has aspirated some blood. She is not cooperative and will not permit an IV to be restarted. She does not answer questions. She lies on her side with her head flexed forward and will not extend her neck when requested nor will she permit you to do so. She will not open her mouth as per your request and it seems that blood is every­ where. According to the surgeon, her sister has cared for her for the past 20 years (parents are deceased) . As far as her sister knows, she is perfectly healthy and has never had an anesthetic before. She is on no medication and has no allergies. Her past cardiac history is unremarkable according to the surgeon. She does not smoke. Blood work done earlier in the day shows a hemoglobin of 1 0.2 g/dL ( 1 02 mmol·L- 1 ) and is otherwise normal.

Ai rway M a n a g e m e n t of a n U n cooperative Down Syn d ro m e Pati ent with a n U p per G l B l eed

She will require a general anesthetic with endotracheal intu­ bation. In addition, she is grossly uncooperative, is exhibiting some evidence of hypovolemia, has features indicative of a dif­ ficult airway, and has probably aspirated some blood.

PATI ENT EVALUATION • What Ki nd of Vital Organ System Reserve

Does Th is Patient Have?

Cardiovascular reserve: The elevated pulse rate and the narrowed pulse pressure suggest an element of hypovolemia. You are hop­ ing that the surgeon is correct and that she has no congenital heart disease (e.g., an endocardial cushion defect) . CNS reserve: She is moderately developmentally delayed and anticipated to be uncooperative and combative on induction and emergence. Her response to sedative hypnotic agents and ketamine for sedation is unpredictable. Respiratory system reserve: She is moderately obese and is expected to have some restrictive lung disease with predictable consequences. In addition, she has probably aspirated blood and has a past history of repeated aspiration pneumonias. Her saturation on blow by oxygen is 92%. It is likely that she has limited oxygen reserves and will rapidly desaturate if she obstructs, or if she becomes apneic. Postoperative mechanical ventilation is a possibility. She is an extreme regurgitation and aspiration risk. AI RWAY EVALUATION A N D MANAGEMENT OPTIONS • Employi ng the Mnemon ics Suggested in

Chapter 1, Does This Patient Have a Difficult Airway?

On MOANS-guided airway evaluation (see section "Difficult BMV: MOANS" in Chapter 1 ) , you gain no confidence that you will be able to ventilate this patient using bag-mask­ ventilation (BMV) when it becomes necessary. If her neck can­ not be extended, a mask seal will be difficult. She is obese and the decrease in compliance may hinder BMV Employing LEMON and CRANE (see sections "Difficult DL Intubation: LEMON" and "Difficult VL Intubation: CRANE" in Chapter 1 ) to assess the difficulty associated with direct and indirect (video) laryngoscopy and intubation reveals that the look of this patient suggests difficulty. When you attempt to evaluate the geometry of her upper airway, you are unable to assess the volume of her mandibular space. This is particularly problematic in a person with DS in which the initial impression is that the tongue is relatively large for the volume of the mouth. You also have no idea where her larynx is relative to the base of her tongue. You are unable to evaluate a Mallampati score and get some idea as to airway access. Additionally, she is obese and you are unable to evaluate the degree of neck mobility. You call for the video-laryngoscope to be available. The mnemonic for difficulties in using extraglottic devices (EGDs) is RODS (see section "Difficult Use of an EGD: RODS"

in Chapter 1). Whether there is restricted mouth opening or not, is unknown. There does not appear to be any upper airway obstruction and the airway is neither distorted nor disrupted. As mentioned earlier, she is obese and the decreased compliance (stiff) may militate against successful ventilation with an EGD. Finally, the patient should be assessed for a potentially diffi­ cult cricorhyrotomy using the mnemonic SHORT (see section "Difficult Cricothyrotomy: SHORT" in Chapter 1 ) . There is no history of prior anterior neck surgery, hematoma, or other overlying process that masks the anatomy. However, she is obese, and in addition, one is unable to ascertain whether access to the anterior neck is possible. There is no history or evidence of radiation or tumor. In summary, she has a potentially difficult airway and is not a candidate for a rapid sequence induction, even though with a stomach potentially full of blood, that would ordinarily be the preferred technique. • What Other Airway Concerns Do You Have in

Patients with OS?

An increased incidence of subglottic stenosis in DS patients is well known. 1-4 This has been attributed, at least in part, to the increased incidence of regurgitation and aspiration in these patients during infancy and early childhood. 1 Therefore, these patients may require an endotracheal tube (ETT) that is one to two sizes smaller than the standard size appropriate for the patient's age. In addition, the DS patient is predisposed to obstructive sleep apnea due to a relatively narrow nasopharynx and large tongue. 5·6 C-spine subluxation is also seen in these patients and may be of concern in airway management? Presently, there is no consensus of opinion with respect to the need for preoperative radiological evaluation of the cervical spine for subluxation for patients with DS. • What Are the Airway Management

Options?

This patient gives every indication that the management of her airway will be difficult. However, the more pressing problem is how to pharmacologically manage her behavior without com­ promising her ability to maintain ventilation and oxygenation and permit either an IV placement and/or to gain control of the airway in a controlled fashion that minimizes the risk of aspiration. Ideally, one would like to identifY a preferable airway tech­ nique (Plan A) , and two alternative methods (Plans B and C) . However, with the limited airway evaluation, the most appro­ priate method chosen must have the least chance of producing apnea, aspiration, or a requirement for rapid action. In addi­ tion, the presence of copious amounts of blood in the airway is likely to render indirect visualization techniques (endoscopes, video-laryngoscopes, optical stylets) to be of limited use. This really leaves one primary option for consideration: sedation and awake intubation employing direct laryngoscopy. Plans B and C will likely include an EGD and the surgeon should be prepared to perform an immediate surgical airway

409

41 0

Ai rway M a n a g e m e n t i n the Operati n g Room

if asked (a double setup) . One would be wise to consider the immediate availability of a lightwand if the airway practitioner is sufficiently skilled in its use (see Chapter 1 2 ) .

MANAG I N G TH E AI RWAY • What Are the Pros and Cons of the Awake/

Sedated Method?

Clearly the sedation and awake intubation approach is not without hazards. The use of sedative hypnotic agents in large oral or intramuscular dosages may provoke paradoxical excite­ ment, or worse, lead to hypoventilation or apnea. Ketamine is an attractive option. Seven mg·kg- 1 (ideal body weight)8-1 1 can be given orally with the expectation that the patient will be dissociated within 20 minutes, at least to the point that an IV can be placed. If the degree of cooperation is not sufficient after this dose, half the original dose can be repeated at 20 minutes. Clearly this is not an option in this case. Four mg·kg- 1 of ideal body weight IM produces reliable sedation and dissociation in approximately 5 minutes. 1 1-15 The margin of safety with ketamine is greater than other sedative hypnotics, such as midazolam, as it preserves ventila­ tory function, muscle tone, and airway protective reflexes. The disadvantages of ketamine include the risk of laryngospasm, increase in secretions, emergence reactions, and post-procedure nausea and vomiting. • How Exactly Would You Manage the Airway

of Th is Patient?

To prepare for airway management, the neck of the patient is prepared in as sterile a fashion as the circumstances will allow and the surgeon and OR team are prepared to perform a surgi­ cal airway (double setup) . Ketamine 4 mg·kg- 1 is then drawn up and ready to administer IM. Propofol 200 mg and succinyl­ choline 1 40 mg are also drawn up. Additionally, an assistant is prepared to place an IV on command if possible. A central line access kit is immediately available. The following airway devices are immediately available for use: •

•

•

•

•

•

•

•

Styleted ETTs of various sizes (5, 6, and 7-mm ID) Two suctions with rigid suction handles LMA-Fastrach'M (intubating LMA) Lightwand loaded onto a 7-mm ID ETT cut at 26 em Macintosh laryngoscope with a #3 blade at the ready Video-laryngoscope with both direct and indirect laryngos­ copy capability (e.g. , CMAC, Karl Storz Endoscopy-America, Inc.) at the ready Flexible bronchoscope at the ready Topical local anesthetic spray (e.g. , 4% lidocaine in a syringe attached to a mucosal atomization device [MAD])

The patient is then placed in the left lateral position on the OR table. An antisialogogue is not administered because it must be administered intramuscularly (see later) . A pulse oximeter is applied when the patient permits, as is supplemental oxygen. When all is ready, the ketamine is administered IM. Sedation/dissociation sufficient to permit an IV placement

is typically achieved within 5 minutes. Gradual initiation of Sellick's maneuver and an awake look is initiated. If the awake look indicates that oro tracheal intubation is likely to be success­ ful, then rapid sequence intubation (RSI) may be performed, or if the patient is intubated immediately following the awake look, propofol can be administered rapidly after the airway is secured and confirmed. The dose of propofol administered must take into consideration the likelihood of hypovolemia. Failure to visualize the airway adequately to intubate or ensure that intubation is possible if RSI is employed, in the face of ongoing acceptable oxygen saturations may lead one to resort to Plan B. In the event adequate oxygen saturation cannot be maintained, a surgical airway must be immediately performed. • How Exactly Was the Airway of This Patient

Managed?

After adequate sedation was achieved with IM ketamine, an awake look was performed in the left lateral decubitus position using a #3 Macintosh laryngoscope. About 50% of the glot­ tis was visualized and tracheal intubation was achieved using a #7.0-mm ID ETT. After confirmation of the proper tracheal tube placement using end-tidal C0 , the patient underwent 2 volume resuscitation and sedation was carefully titrated using IV propofol. GI endoscopy revealed a bleeding duodenal ulcer. Hemostasis was achieved. The patient was transferred to the ICU intubated and ventilated for further evaluation of her pre­ sumed aspiration and ventilatory management.

ADDITIONAL CON S I D E RATIONS • Should an Antisialogogue be Given When

Ketamine Is Employed?

As a general comment, antisialogogues are typically used when­ ever topical anesthesia of the oro- and hypopharynx is to be attempted because it minimizes the dilution of local anesthetic agent by saliva and improves the degree of topical anesthe­ sia achieved. In this particular case, it was omitted because it would have required an IM injection and time for the drying effect to occur. Ketamine does stimulate tracheobronchial and salivary secre­ tions, and this effect of the drug can potentially cause laryngo­ spasm. 1 2 An antisialogogue, such as glycopyrrolate or atropine, is often given IM 1 5 to 20 minutes prior to the administra­ tion of ketamine to reduce these secretions. Glycopyrrolate is preferred because it produces less intense tachycardia. Unlike other tertiary-substituted antimuscarinics (scopolamine and atropine) , glycopyrrolate is a polar quaternary-substituted ammonium compound, which does not cross the blood-brain barrier and therefore avoids the risk of producing confusion and sedation. • How Common Is La ryngospasm with

Ketamine?

Laryngospasm is associated with all of the sedative hypnotics to some extent, including ketamine. The incidence of laryngo­ spasm with ketamine is about 1 % (ranging between 0.0 1 7%

Ai rway M a n a g e m e n t of a n U n cooperative Down Syn d ro m e Pati ent with a n U p per G l B l eed

and 1 .4% in various studies, including studies with data from over 1 1 ,000 patients) . 1 3-16 It manifests as transient stridor. It is likely related to ketamine-induced sensitization of laryngeal reflexes, and in some cases is thought to be related to exces­ sive upper respiratory secretions. 1 2 Thus, the recommendation has been made that an antisialogogue be coadministered with ketamine. Risk factors for laryngospasm include respiratory infection (fivefold increase) and age (three times greater risk in infants aged 1 -3 months than the average) . 17 One study of nearly 1 200 pediatric patients with laryngospasm reported the incidence of complications as hypoxemia 3.2%, aspiration 1 . 1 %, and cardiac arrest 0 . 5 % . 1 5 • How Common Are Emergence Reactions

with Ketamine?

Emergence delirium is the most common side effect of ket­ amine. 18 This response is thought to be caused by the drug's depression of CNS visual/auditory relay nuclei causing altered perception and interpretation of visual and auditory stimuli. 19 The occurrence of emergence reactions is associated with age (adults > children) , gender (females > males) , anxiety level, and psychological state prior to the procedure. 18•2 0• 2 1 The inci­ dence varies but may be as high as 1 0% to 30% in adults with a much lower occurrence in children. Severe agitation occurs in 1 .6% and mild agitation in 1 7.6% of pediatric patients. 19 Emergence reactions are less common in older children ( 1 2 . 1 % i n those more than 5 years vs. 22.5% i n children under 5 years of age) . 20 Small doses of midazolam have been used to treat severe emergence reactions. However, the prophylactic coadministra­ tion of benzodiazepines is not recommended since they have no proven benefit, delay ketamine metabolism thereby prolonging recovery, may actually increase the incidence of recovery agita­ tion in specific patient populations, and increase the risk of respiratory depression. 1 7•22-2 9 • Should These Patients be Recovered in a

Dark and Quiet Environ ment to Prevent Emergence Reactions?

Whether or not a quiet, secluded environment which limits stimuli during the post-recovery period decreases the inci­ dence of emergence reactions is debatable. 1 2 Some suggest that pre-procedure discussion with the patient (adult or child) has a greater impact on reducing the incidence of recovery agita­ tion. 1 2•23 However, the prevailing impression is that less stimu­ lation is advantageous. • How Often Do Patients Given Keta mine

Vomit Post-Proced u re?

Vomiting occurs in 6.7% of patients, which often persists into the recovery phase, and is also age related, being more common in younger children ( 1 2 . 5 % incidence in children under 5 years vs. 3 . 5 % in those more than 5 years of age) . 20 There have been no documented reports of clinically signifi­ cant aspiration with ketamine when used in patients without contraindications. 26

S U M MARY This case study serves as a prototype for the uncooperative, dif­ ficult airway with a full stomach, has incipient hemodynamic instability, and is an emergency. Time to plan an approach is limited and hindered by the fact that the patient has no IV access. In an emergency, the practitioner does not have the luxury of time, and rigid adherence to the difficult and failed algorithms is advised. Patient control is achieved with IM ketamine thereby allowing successful IV access. The Difficult Airway Algorithm (Chapter 2) with alternative plans was employed to guide actions directed to managing the airway in this patient. At each step, the imperative is to ensure that adequate gas exchange occurs and one does not burn bridges.

REFERENCES 1. Boseley ME, Link DT, Shott SR, et al. Laryngotracheoplasty for sub­ glottic stenosis in Down syndrome children: the Cincinnati experience. IntJ Pediatr Otorhinolaryngol. 200 1 ;57: 1 1 - 1 5 . 2. Mitchell RB, Call E , Kelly J. Diagnosis and therapy for airway obstruc­ tion in children with Down syndrome. Arch Otolaryngol Head Neck Surg. 2003; 1 29:642-64 5 . 3 . Jacobs I N , Gray RF, Todd N W Upper airway obstruction i n children with Down syndrome. Arch Otolaryngol Head Neck Surg. 1 996; 1 22:945-950. 4. Miller R, Gray SD, Cotton RT, Myer CM III, Netterville J. Subglottic stenosis and Down syndrome. Am J Otolaryngol. 1 990; I I :274-277. 5. Resta 0, Barbaro MP, Giliberti T, et al. Sleep related breathing disorders in adults with Down syndrome. Downs Syndr Res Pract. 2003;8: 1 1 5 - 1 1 9. 6. Dahlqvist A, Rask E, Rosenqvist CJ, Sahlin C, Franklin KA. Sleep apnea and Down's syndrome. Acta Otolaryngol. 2003; 1 23 : I 094- 1 097. 7. Kanamori G, Witter M, Brown J, Williams-Smith L. Orolaryngologic manifestations of Down syndrome. Otolaryngo! C!in North Am. 2000;33: 1 28 5 - 1 292. 8 . Rosenberg M. Oral ketamine for deep sedation of difficult-to-manage chil­ dren who are mentally handicapped: case report. Pediatr Dent. 1 9 9 1 ; 1 3 : 22 1 -223. 9. Younge PA, Kendall JM. Sedation for children requiring wound repair: a randomised controlled double blind comparison of oral midazolam and oral ketamine. Emerg Medj. 200 1 ; 1 8 :30-33. 10. Turhanoglu S, Kararmaz A, Ozyilmaz MA, Kaya S, Tok D . Effects of different doses of oral ketamine for premedication of children. Eur J Anaesthesia!. 2003;20 : 56-60. 1 1 . Zane R. The morbidly obese patient. In: Walls R, Murphy M, Luten R, Schneider R, eds. Manual of Emergency Airway Management. 2nd ed. Philadelphia, PA: Lippincott Williams and Wilkins; 2004:302-306. 12. Green S . Dissociative agents. In: Kraus B, Bructowicz R, eds. Pediatric Procedural Sedation and Analgesia. Philadelphia, PA: Lippincott, Williams and Wilkins; 1 999:47-54. 13. Green SM, Johnson NE. Ketamine sedation for pediatric procedures: part 2, review and implications. Ann Emerg Med. 1 990; 1 9: I 033- 1 046. 14. Green SM, Nakamura R, Johnson NE. Ketamine sedation for pediat­ ric procedures: part I , a prospective series. Ann Emerg Med. 1 990; 1 9 : 1 024- 1 032. 1 5 . Green SM, Rothrock SG, Lynch EL, et al. Intramuscular ketamine for pediatric sedation in the emergency department: safety profile in 1 022 cases. Ann Emerg Med. 1 998;3 1 :688-697. 16. Green SM, Rothrock SG, Harris T, et a!. Intravenous ketamine for pedi­ atric sedation in the emergency department: safety profile with 1 5 6 cases. Acad Emerg Med. 1 998; 5 : 97 1 -976. 17. Sachetti A, Gerardi M. Emergency department procedural sedation and analgesia. In: Strange G, Ahrens W, Lelyveld S, et al. , eds. Pediatric Emergency Medicine. New York, NY: McGraw Hill; 2002: 1 8 5 - 1 96. 18. Muse D. Conscious and deep sedation. In: Harwood-Nuss A, Wolfson A, Linden C, et al. , eds. 7he Clinical Practice of Emergency Medicine. Philadelphia, PA: Lippincott, Williams and Wilkins; 200 1 : 1 75 8- 1 762. 1 9. Reeves J, Glass P, Lubarsky D. Nonbarbiturate intravenous anesthetics. In: Miller R, Cuehiara R, Miller E, et a!. , eds. Anesthesia. Philadelphia, PA: Churchill Livingstone; 2000:249-256.

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Ai rway M a n a g e m e n t i n the Operati n g Room 20. Green SM, Kuppermann N, Rothrock SG, Hummel CB, Ho M. Predictors of adverse events with intramuscular ketamine sedation in children. Ann Emerg Med. 2000;35:35-42. 2 1 . Hostetler MA, Davis CO. Prospective age-based comparison of behavioral reactions occurring after ketamine sedation in the ED. Am } Emerg Med. 2002;20:463-468. 22. Reich DL, Silvay G. Ketamine: an update on the first twenty-five years of clinical experience. Can } Anaesth. 1 989;36: 1 86- 1 97. 23. White PF, Way WL , Trevor AJ. Ketamine-its pharmacology and thera­ peutic uses. Anesthesiology. 1 982;56: 1 1 9- 1 36. 24. Wathen JE, Roback MG, Mackenzie T, Bothner JP. Does midazolam alter the clinical effects of intravenous ketamine sedation in children? A double­ blind, randomized, controlled, emergency department trial. Ann Emerg Med. 2000;36:579-5 88. 25. Dachs RJ, Innes GM. Intravenous ketamine sedation of pediatric patients in the emergency department. Ann Emerg Med. 1 997;29 : 1 46- 1 50. 26. Green SM, Krauss B. Procedural sedation and analgesia. In: Roberts J, Hedges J, eds. Clinical Procedures in Emergency Medicine. Philadelphia, PA: Saunders; 2004:5 96-620. 27. Mace SE, Barata lA, Cravero JP, et a!. Clinical policy: evidence-based approach to pharmacologic agents used in pediatric sedation and analgesia in the emergency department. Ann Emerg Med. 2004;44:342-377. 28. Strayer RJ, Nelson LS. Adverse events associated with ketamine for proce­ dural sedation in adults. Am } Emerg Med. 2008;26: 9 8 5 - 1 028. 29. Melendez E, Bachur R. Serious adverse events during procedural sedation with ketamine. Pediatr Emerg Care. 2009;25:325-328.

SELF - EVALUATION QU ESTIONS 3 5 . 1 . Down syndrome patients are known t o have the follow­ ing attributes that may lead to failed intubation: A. obstructive sleep apnea B. large tongue

C. tendency to have subglottic stenosis D. C-spine subluxation E. all of the above 3 5 . 2 . Ketamine used in the uncooperative patient A. aggravates the degree of cooperation because it is a dissociative agent B. produces such salivation that laryngospasm is a com­ mon problem C. is contraindicated because of the high incidence of emergency delirium D. can be administered PO or IM E. midazolam has been proven to reduce the incidence of ketamine-induced emergency delirium in adults and children 3 5 . 3 . Oral or IM ketamine is useful in the management of the uncooperative patient. Which of the following is TRUE A. The dose of oral ketamine is 7.0 mg·kg- 1 • B . Midazolam prevents emergence reactions. C. Glycopyrrolate should be coadministered with ket­ amine to prevent laryngospasm. D. Ketamine is contraindicated in developmentally delayed individuals. E. All of the above.

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C H A PT E R 3 6

Airway Manage ment of a Patient with a H istory of Ora l an d Cervica l Radiation Thera py Jan R. Morris

CAS E PRESENTATION

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AN ESTHETIC CO N S I D E RATIO N S . . . . . . . . . . . . . . . . . . . 4 1 3 AI RWAY MANAG E M E NT . . . . . . . . . . . . . . . . . . . . . . . . . 4 1 8 POST-I NTU BATION CO N S I D ERATIONS . . . . . . . . . . . .

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S U M MARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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SELF-EVALUATIO N Q U ESTI O N S . . . . . . . . . . . . . . . . . . . 422

extension is decreased. Palpation of the submandibular tissues reveals a woody, indurated consistency. On inspection, telan­ giectasia and pallor of the submandibular skin are noted. The right neck has the typical appearance of a previous neck dissec­ tion. The mucosa of the tongue appears dry. Laboratory data reveal normal electrolytes and a hemoglobin of 1 40 g· L - 1 • EKG reveals nonspecific ST and T changes.

AN ESTH ETIC CO N S I D E RATIONS • Is Th is Patient Fit for Anesthesia?

CASE PRESENTATION A 68-year-old male was found on CT to have a right lung nod­ ule and paratracheal lymphadenopathy. He was then scheduled for diagnostic bronchoscopy and mediastinoscopy. Twenty years ago, he was diagnosed with carcinoma of the right submandibular gland, and underwent excision of the gland, right radical neck dissection, and a course of radiother­ apy. He quit smoking several years ago and has had hyperten­ sion for about 5 years. He has had a nonproductive cough for several months. His only medication is metoprolol. On examination, he is in no distress at rest. His vital signs are: blood pressure 1 40/90, heart rate 70, and respiratory rate 1 8 . Oxygen saturation on room air is 96%. His weight is 94 kg and he is 1 70 em tall. Auscultation of the chest reveals decreased breath sounds bilaterally but no rales or rhonchi, and normal heart sounds. No carotid bruits are evident. Airway examination reveals a Mallampati IV classification. Mouth opening is 2 . 5 em and mandibular protrusion is less than 1 em. Full upper dentition is present but the mandible is edentulous. The thyromental distance is normal. Cervical spine

The patient has hypertension which is adequately controlled for his surgical procedure. Carcinoma of the lung is suspected on diagnostic imaging. He does not require further medical optimization. • What Anesthetic Technique Is Req uired?

General anesthesia with endotracheal intubation is required for a brief but stimulating surgical procedure. • What Anatomic and Pathophysiologic

Changes Occur Fol lowing Radiotherapy to the Structu res of the Oral Cavity and Neck?

Radiotherapy inflicts a radiochemical injury to both normal and malignant cells. 1 The damage is related to the total radia­ tion dose and the method of radiotherapy delivery. In order to achieve adequate tumor control, damage to normal tissues is inevitable.1-3 Radiation also activates various cellular signal­ ing pathways that lead to activation of proinB.ammatory and profibrotic cytokines, vascular injury, and activation of the coagulation cascade.4 Early (acute) tissue toxicities from radio­ therapy are arbitrarily considered to occur within 90 days of the commencement of treatment, and late effects beyond 90 days of treatment. 2' 5 Early side effects are observed shortly after

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Ai rway M a n a g e m e n t i n the Operati n g Room

a course of radiotherapy, whereas late effects are manifest after a latent period and may not be evident until years following the radiotherapy. 2 ·6 In general, tissues with rapidly dividing cell populations such as mucous membranes and skin demonstrate acute effects of radiation (mucositis, desquamation) , whereas those with slowly proliferating cells such as organ parenchyma, connective, and vascular tissues demonstrate late effects. 2 •7 Interactions between acute and chronic reactions can occur resulting in "consequential late effects" due to loss of protec­ tive barrier function in the acute phase resulting in second­ ary tissue injury. 2 The severity of the late effects of radiation therapy in general cannot be predicted by the severity of the acute effects? Late radiation sequelae are usually irreversible and progressive, with the severity increasing with time. 2 Progression of late effects have been reported up to 34 years after therapy.4 The pathogenesis of late radiation effects are based on complex pathophysiological processes which include radiation-induced change in parenchymal cells (cell death) , fibroblasts (differen­ tiation) , and vascular endothelial cells (loss of capillaries) . 2 All of these cells and macrophages interact through a variety of cytokines and growth factors in an orchestrated response that results in progressive parenchymal damage and loss of function within the irradiated volume. 2 Damage to the vasculature and release of vasoactive cytokines lead to increased vascular perme­ ability, deposition of fibrin in the perivascular interstitium, and subsequent replacement by collagen.4'8 An increase in collagen content can be seen as early as 1 week following irradiation.8 Following radiation therapy to the oral cavity, pharynx, or lar­ ynx, the mucous membranes can become erythematous within 1 week, and develop areas with white pseudomembranes (muco­ sitis) at about 2 weeks? The patches of mucositis may coalesce by the third week.7 1his acute mucosal reaction usually heals within 2 to 4 weeks following completion of radiotherapy, although ulceration and necrosis can occur.6 Late effects of radiation on the mucosa are characterized by thinning or atrophy of the epi­ thelium, telangiectasia, dryness, a loss of mucosal mobility, sub­ mucosal induration, and occasionally chronic ulceration and necrosis.8 1he mucosa is fragile and more susceptible than normal to mechanical injury ? Edema is seen in the subcutaneous or sub­ mucosal soft tissue in the early phase following radiotherapy, can persist for 6 to 1 2 months,9 and can become chronic.5•10 Edema occurs when vascular permeability is increased by inflammatory mediators or when venous or lymphatic passages are obstructed1 1 and is associated with duration of radiother­ apy treatments, dose per fraction, total number of fractions, number of fractions per day, and interval between fractions . 1 2 Radiotherapy-induced laryngeal edema occurs on a continuum from mild to severe, 1 2 and can be graded from 0 (absent) to 4 (necrosis) . 1 3 After radiotherapy for head and neck cancer, 1 5% to 59% of patients develop ;::: Grade 2 laryngeal edema within 2 years. 14 Grade 2 (moderate) edema is not associated with significant or symptomatic airway obstruction. 13 However, severe laryngeal edema (Grade 3) may cause airway obstruc­ tion and require urgent tracheotomy. 14 Laryngeal edema which persists for more than 3 months after radiotherapy may suggest the presence of residual or recurrent tumor. 14 Local recurrence in about 50% of patients was noted to be associated with per­ sistent laryngeal edema. 14

The pathogenesis of radiation fibrosis is complex. Radiation of fibroblasts leads to induced differentiation and a significant increase in collagen deposition15 and radiation fibrosis may be considered to be a form of injury response in which there is a continuous signal for connective tissue deposition and/or a fail­ ure of regulatory processes that normally terminate fibrogenesis. 16 Fibrosis is one of the most common delayed radiation-associated manifestations? It usually appears in subcutaneous tissues within 6 to 1 2 months of treatment,7 although it can occur as early as 4 to 1 2 weeks.8 The fibrosis tends to be slowly progressive,7 non­ homogeneous, and variable in extent and severity from site to site. 17 The severity of the fibrosis increases when high total doses of radiation and large fraction sizes are used.6 The risk of devel­ oping moderate to severe fibrosis has been reported to be about 40%.5 The affected soft tissue loses elasticity and subcutaneous fat8 and is indurated to palpation.1 '8 In the presence of moderate to severe fibrosis, contracture of the tissues also occurs. 1 In severe cases, the soft tissues develop a woody consistency and may form a hard mass fixed to skin and underlying muscle or bone (see Figure 36-1) .7 Obstructive lymphedema may also be associated with fibrosis.7 Radiation therapy to the neck can produce a limita­ tion of neck extension (see Figure 36-2) .8'18 High-dose irradiation of metastatic cervical lymphadenopathy results in more subcu­ taneous fibrosis in the neck than does a comparable dose in the absence of palpable lymphadenopathy ? Voluntary muscle exposed to high-dose irradiation can also develop fibrosis, and when the muscles of mastication (the tem­ poralis, masseter, and pterygoid muscles) are involved, trismus

F I G U R E 36- 1 . A p peara nce of the exte r n a l neck fol l ow i n g rad io­ thera py. The a nterior neck d e m o n strates tel a n g iecta s i a and a t h i c k­ ened a ppea ra nce.

Ai rway M a n a g e m e n t of a Patient with a H i story of Ora l a n d Cervica l Rad iation Thera py

F I G U R E 36-2. L i m ited cervica l s p i n e exte n s i o n fol l ow i n g rad i oth era py.

F I G U R E 36-3. L i m ited mouth open i n g fo l l ow i n g rad ioth e ra py.

can be produced (see Figure 36-3) ? The temporomandibular joint itself is however relatively resistant to ankylosis second­ ary to radiation injury? Radiotherapy has been reported to reduce mouth opening by 1 8% (SD, 1 7%) within 1 2 months of follow-up. 19'20 Although trismus may be apparent during the course of radiation therapy, it may not become apparent until

3 to 6 months after radiotherapy, 19 The prevalence of trismus after radiotherapy for head and neck cancer has been reported to be between 5% and 38%. 20'2 1 Fibrosis of the pharyngeal musculature can produce swallowing dysfunction22 and a pre­ disposition to aspiration.3 Hypopharyngeal stenosis is caused by fibrosis of the lamina propria and submucosa. 23 Stenosis of the pharynx or supraglottic larynx can occur and lead to airway compromise (see Figures 36-4 to 36- 1 0) ?· 23'26 Choana! steno­ sis thought to be associated with severe mucosal reaction fol­ lowed by fibrosis has also been reported after radiotherapy for nasopharyngeal carcinoma. 27 Radiotherapy in head and neck cancer patients has also been associated with the development of obstructive sleep apnea. 2 8 The cause is likely multifactorial and may include persistent mucosal edema, decreased elasticity, increased fibrosis, and poor pharyngeal constriction. 2 8 Radiation therapy can also produce vascular injury which includes intimal thickening, fragmentation of the internal elas­ tic membrane, atheroma formation, and fibrosis of the media and adventitia? In medium-sized vessels intimal fibrosis is the most common lesion. 16 The capillary network is particularly vulnerable to radiotherapy and obstruction can occur due to endothelial cell injury and thrombosis. 1 6 Telangiectasia and atrophy are common late effects15'16 and a reduction in the microvascular network can ultimately lead to ischemia. 17 Tissue ischemia may be a consequence of or contribute to the radiation injury. 16 Narrowing or obstruction of larger arteries can also occur, as can occlusive thrombosis. 1 7 The changes in the vessel walls are similar to those associated with artherosclerosis due to aging.8 Symptomatic carotid atherosclerosis can be a result of cervical irradiation and may require surgical intervention. 29 Laryngeal cartilage covered by normal mucous membrane usually tolerates conventional fractionated high-dose radiation therapy.6·7 However, arytenoid edema, chrondritis, vocal cord palsy,3.3° and rarely, chondronecrosis can occur (see Figures 36-4B, 36-5B, 36-7, 36-8B, 36-9B, and 36- 1 0) . 1 Laryngeal edema can occur at any time following the completion of radiation therapy9 and can produce airway compromise. 10 Stenosis of the larynx espe­ cially at the glottic level associated with fixation of the vocal cords due to scar at the posterior glottis is not unusual after radiotherapy for carcinoma of the larynx. 25 Laryngeal chondronecrosis has been reported to occur up to 22 years following radiotherapy. 10 Radiation injury to the salivary glands produces a decrease in saliva production and a change in the composition of saliva? Typically, about 60% to 65% of the total salivary volume is produced by the parotid glands, 20% to 30% by the subman­ dibular glands, and 2% to 5% by the sublingual glands? The remainder of the salivary volume is produced by anonymous minor salivary glands distributed throughout the oral cavity and pharynx and which are variable from patient to patient? The degree of salivary gland dysfunction depends on the vol­ ume of the glands included in the radiation field and the total dose administered? It is usually not possible to irradiate the pharynx or the upper jugular nodes without irradiating the sub­ mandibular glands; however, the parotid and submandibular glands can be partially shielded during treatment.6 Intensity­ modulated radiotherapy can also be used to preserve salivary flow.31•3 2 A significant reduction in salivary flow occurs within 1 week of fractionated radiotherapy to the head and neck?

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Ai rway M a n a g e m e n t i n the Operati n g Room

F I G U R E 36-4. CT sca n s of the head a n d neck. (A) Th i s CT sca n s h ows normal soft tissues of the u p per a i rway with normal va l l ec u l a . N ote the b i l atera l a i r-fi l led dep ressi o n s at t h i s l eve l . (B) Th i s CT sca n s h ows the post-rad ioth era py soft-tissue swe l l i ng in the va l l e c u l a .

F I G U R E 36-5. C T sca n s o f the h e a d a n d neck. (A) Th i s C T sca n s h ows a n o r m a l e p i g l ottis. (B) Th i s C T sca n s h ows post-ra d i othera py t h i c k­ e n i ng of the e p i g l ottis.

F I G U R E 36-6. La rynge a l i n l et view t h ro u g h a bro n c h oscope s h ows a n o r m a l e p i g l ottis. N ote the s h a r p leaf- l i ke edge a l o n g the rig ht latera l a s pect.

F I G U R E 36-7. La ryng e a l i n l et view t h ro u g h a bro n c h oscope s h ows the a p peara nce of the edemato u s e p i g l otti s fol l owi ng rad i oth era py.

Ai rway M a n a g e m e n t of a Patient with a H i story of Ora l a n d Cervica l Rad iation Thera py

F I G U R E 36-8. CT sca n s of the head a n d neck: (A) n o r m a l soft tissues of the u pper a i rway with n o r m a l a ryep i g l ottic fol d s (0.25 em); a n d ( B ) t h i c ken i n g o f t h e r i g h t a ryepig l otti c fol d fo l l ow i n g rad i othera py (0.74 em).

F I G U R E 36-9. CT sca n s of the head a n d neck: (A) n o r m a l soft tissue th ickness at the posterior co m m i s s u re (0.23 em); a n d (B) edema at the l evel of a ryte n o i d s ca rti lages and the posterior com m i s s u re ( 1 . 1 2 em) fol l owi n g rad ioth e ra py.

F I G U R E 36- 1 0. Laryngea l i n let view t h ro u g h a bro n c h oscope s h ows the a p peara n ce of the a rytenoid ca rti lages and adjacent su p ra g l otti c a rea fol l owi ng rad i othera py. N ote the exten s ive t h i c k­ e n i ng a n d tissue d i stortio n .

Salivary flow may become barely measurable by the end of a 6- to 8-week course of treatment and the xerostomia may be permanent. 8 Xerostomia causes discomfort, alters taste acuity, and contributes to a deterioration in dental hygiene because the tissues become tender? The diminished salivary flow has

an altered electrolyte content and reduced pH, and promotes dental decay as the normal oral microflora is altered to a highly cariogenic microbial population? In the absence of stringent measures to protect the teeth, caries can develop within 3 to 6 months and lead to complete destruction of the dentition within 3 to 5 years? Dental extractions from an irradiated mandible can precipitate osteoradionecrosis.6 Infection of the underlying bone related to carious teeth can also lead to osteo­ radionecrosis more commonly seen in the mandible due to its relatively poor blood supply as compared to the maxilla.4 Hypothyroidism occurs in 5% to 1 0% of patients who undergo irradiation of the lower neck,6 and fibrosis of the api­ cal segments of the lungs can also occur? Patients with collagen vascular diseases such as scleroderma, rheumatoid arthritis, and systemic lupus erythematosis appear to have an increased incidence and severity of late normal tissue radiation toxicity16 and comorbidities with impaired vascularity such as diabetes and hypertension may have an adverse effect.4 Age may also be a factor.4 The patient presented here had palpable fibrosis of the sub­ mandibular tissues, decreased cervical extension, trismus, com­ plete loss of mandibular dentition, and a dry mouth.

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Ai rway M a n a g e m e n t i n the Operati n g Room

AI RWAY MANAGEMENT • What Airway Management Difficulties Can

be Anticipated Fol lowing Radiotherapy to the Ora l Cavity, Pharynx, Larynx, or Neck?

Radiotherapy to the oral cavity, pharynx, larynx, or neck can result in limited mouth opening, limited cervical spine exten­ sion, noncompliant immobile fibrotic soft tissue in the floor of the mouth and pharynx, edema and fibrosis of the laryn­ geal walls,31 and vocal cord dysfunction.30 Airway management can be difficult in the presence of these anatomic changes. The degree of difficulty is dependent on the site and extent of the altered anatomy.

• Can Ventilation by Face Mask or Extraglottic

Device be Anticipated to be More Difficult After Radiotherapy to the Structures of the U pper Ai rway?

In a review of 53,04 1 general anesthetics in which mask­ ventilation had been attempted, Kheterpal et al.33 identified 77 cases of impossible mask-ventilation (0. 1 5%). Of the 77 patients who were impossible to mask-ventilate, 1 9 (25%) also demon­ strated difficult intubation. However, the incidence of difficult intubation in the subgroup of patients with neck radiation was not provided.33 Both univariate and multivariate analyses dem­ onstrated neck radiation to be the most significant clinicalpredictor of impossible mask-ventilation. Of the subgroup of 3 1 0 patients with neck radiation, three could not be ventilated. Severely limited mandibular protrusion is an independent predictor of difficult (inadequate, unstable, or requiring two providers) mask­ ventilation,34 and neck radiation can be associated with reduced mandibular mobility. Limited or severely limited mandibular protrusion is an independent predictor of difficult or impos­ sible mask-ventilation combined with difficult intubation. 34 In 20 1 3 Kheterpal et al.35 reported an incidence of 0.4% for difficult mask-ventilation (DMV) combined with difficult laryngoscopy (DL) in a series of 1 76,679 patients undergoing general anesthesia. DMV was defined as Grade 3 (inadequate to maintain oxygenation, unstable, or requiring two providers) or Grade 4 (impossible) , and DL as Cormack-Lehane 3 or 4 views or 2:: 4 intubation attempts inclusive of direct or video­ laryngoscopy. Neck mass or radiation was an independent predictor of DMV combined with DL.35 Mask-ventilation and laryngoscopy serve as primary rescue techniques for each other and the inability to mask-ventilate in the setting of a difficult intubation has significant potential for morbidity and mortality. 34·35 Giraud et al. 18 reported face-mask-ventilation to be easy fol­ lowing induction of general anesthesia in nine patients after oral or cervical radiation. Laryngeal mask airway (LMA) place­ ment was often difficult but was successful in all five patients who had received oral radiotherapy, and ventilation was sat­ isfactory. 18 Two patients required lateral introduction of the LMA due to limitation of mouth opening. 18 LMA place­ ment was easy in the four patients who had received cervical radiation, but positive-pressure ventilation was difficult. 18 On

fiberoptic examination through the LMA, the vocal cords could not be visualized in any of these four patients due to vestibular­ fold collapse. A large epiglottis was also seen in two of these patients. Muscle relaxation did not improve the laryngeal view. Ventilation was impossible in two of the four patients; however orotracheal intubation was successful. Bronchoscopic intuba­ tion via the LMA was not attempted as the glottis could not be visualized. The authors theorized that the presence of the LMA in a narrowed, non-distensible hypopharynx may have compressed the larynx and thereby produced glottic collapse. 18 Ferson et al.36 reported the use of the Intubating LMA­ Fastrach (ILMA) in 254 patients with difficult-to-manage airways, of whom 40 had airway changes related to previous surgery, radiation therapy, or both. In this subset of patients, the authors reported that correct positioning of the ILMA was more difficult, and 1 0 patients required the use of a smaller ILMA than that indicated by the patient's height and weight. There were no failures to insert the ILMA and ventilation was possible in all cases. Bronchoscopically guided intubation through the ILMA was also successful in all 40 patients. The authors felt that a loss of elasticity due to fibrosis in the neck tissues caused positioning of the ILMA to be more difficult and suggested that bronchoscopic guidance be used when attempt­ ing intubation through the ILMA in this group of patients.36 Langeron et al. 37 compared the efficacy of blind intubation through the ILMA with bronchoscopic intubation in a group of 1 00 patients with anticipated difficult intubation undergo­ ing scheduled surgery. In this prospective randomized crossover study, following the induction of general anesthesia, intubation was initially attempted by blind intubation through the ILMA or bronchoscopic intubation through an Ovassapian Airway. In the event of failure of the first technique, the alternative tech­ nique was utilized. The first randomly assigned technique failed in seven patients, four in the bronchoscopic group and three in the ILMA group. All were successfully intubated by the alterna­ tive technique. In the ILMA group, all three failures occurred in patients who had undergone previous cervical radiotherapy scheduled for ENT cancer surgery. In these patients, ventila­ tion through the ILMA was not optimal for performing blind intubation, alignment of the ILMA was difficult, and increased leaks occurred during ventilation, although oxygen desatura­ tion did not occur. The authors concluded that the use of the ILMA could not be recommended in patients with previous cervical radiotherapy. 37 Siddiqui et al.38 reported a case of airway rescue using an LMA-SupremeT" in a patient who had undergone radiotherapy and who had severe trismus. Mask-ventilation was difficult. The airway was maintained with the LMA-SupremeT" until an open tracheotomy was performed. Singh et al.39 similarly reported a case of airway rescue with the AMBU-LM Aura Once• in a post-radiotherapy patient who was in respiratory distress. Mask­ ventilation was difficult and intubation by direct laryngoscopy failed after three attempts. The airway was maintained with the AMBU-LM Aura Once' until a tracheotomy was completed. In 20 1 2 Ramachandran et al.40 reviewed 1 5 ,795 patients who underwent general anesthesia with planned utilization of an LMA-UniqueTM (uLMAT") . uLMAT" failure occurred in 1 . 1 o/o of cases. Surgical table rotation was identified as the most

Ai rway M a n a g e m e n t of a Patient with a H i story of Ora l a n d Cervica l Rad iation Thera py

significant independent risk factor for device failure and in this subgroup surgery was on the head and neck in one-third, although neck radiation was not identified as a risk factor for device failure. The incidence of DMV was increased threefold in patients with uLMATM failure. Following cervical radiotherapy, mask-ventilation may be impossible,33 and the use of an LMA for airway management may not be successful due to obstruction at the level of the larynx. 18 Positioning of the ILMA36'37 and ventilation through the ILMA may also be more difficult.37 Laryngeal obstruction would also preclude ventilation using other extraglottic devices. • Can Endotracheal I ntubation by Direct

Laryngoscopy be More Difficult Fol lowing Oral or Cervical Radiotherapy?

Reduced mouth opening due to fibrosis of the muscles of mastication, reduced cervical spine extension, and fibrosis of the structures of the floor of the mouth can make visualiza­ tion of the glottis by direct laryngoscopy difficult or impos­ sible. Fibrotic subcutaneous and submucosal soft tissues lack compliance and may constitute a poorly mobile woody mass that cannot be elevated easily, if at all, on direct laryngoscopy. Post-irradiation atrophic mucosa is also easily traumatized and bleeding can readily occur. A thickened edematous epi­ glottis can obscure glottic visualization, and decreased vocal cord mobility may interfere with glottic cannulation (see Figures 36-5B, 36-7, and 36-9B) . Tomioka et al.41 reported ventilation by face mask under general anesthesia to be easy in a patient who had undergone radiotherapy for a pharyngeal tumor. However, intubation with a #7.0 endotracheal tube was not possible due to tracheal steno­ sis, which Tomioka et alY postulated may have been produced by the radiation therapy. Yaney42 reported a Cormack-Lehane Gade 3 view with a #3 Macintosh blade following induction of general anesthesia in a patient who had undergone left radical neck dissection and postoperative radiation 1 0 years previously. A "frozen larynx" that was "fibrotic and swollen" was described. Intubation with a #3 Miller blade and a #6. 5 endotracheal tube was difficult but successful.42 Reed and Frost23 reported a case of hypopharyngeal stenosis following cervical radiation. The larynx could not be visual­ ized by direct laryngoscopy. Mask-ventilation was performed and intubation over a flexible bronchoscopic laryngoscope was successful. 23 In 20 1 2 , Iseli et alY reported a series of 1 52 dif­ ficult airway cases associated with head and neck pathology. Intubation techniques included gas induction followed by "routine" laryngoscopy (38), vessel dilator cricothyrotomy (44) , awake nasotracheal bronchoscopic intubation (68) , and awake tracheotomy (2) . Of those who had undergone previous radio­ therapy, 34 were intubated without difficulty, five experienced some difficulty (> 3 attempts or > 1 0 minutes of attempted intubation), and three required a change of the intubation plan. It is unclear how many of the patients who had radiotherapy underwent direct laryngoscopy. One "can't ventilate, can't intu­ bate" patient was "safely allowed to emerge." Radiotherapy was identified as a predictor of airway difficulty.

Truong and Truong2 1 reported a patient who required bilat­ eral dacryocystorhinostomy who had severe trismus after radio­ therapy. The inter-incisor distance was 9 mm. The first side was operated on following awake nasotracheal intubation. The second surgery was done after retromolar bronchoscopic intu­ bation under general anesthesia. Delbridge et al.44 reported 30 consecutive patients who had been treated with head and neck radiation for childhood malig­ nancy who presented for thyroidectomy. Twenty-eight patients underwent straightforward intubation by laryngoscopy after induction of general anesthesia but rwo could not be intubated. One underwent flexible bronchoscopic intubation under local anesthesia and one who had a Grade 4 laryngeal view had the surgery completed with a laryngeal mask. Huitink et al.45 described awake fibercapnic intubation in a series of 37 head and neck cancer patients with difficult airways, 29 of whom had chemoradiation. A difficult airway was defined as one in which the airway could not be intubated using conventional laryngoscopy. Arne et al.46 reported difficult intubation in 1 2.3% of patients undergoing ENT cancer surgery, although the number of patients who had previous radiotherapy was not specified. Patients with neck pathology have been identified as having an increased risk of failed direct laryngoscopy.47 • Can Endotracheal I ntubation by Video­

Laryngoscopy or Alternate I ntubation Techniq ues be More Difficult Following Ora l or Cervical Radiotherapy?

Alternative intubation techniques can also be more difficult following radiation-induced changes to the upper airway. The light-guided technique using a lightwand is best avoided in the presence of anatomic distortion of the airway.48 Retrograde intubation may be feasible although laryngotracheal abnormal­ ity has been cited as a relative contraindication to this technique as well.49 Limited mouth opening may preclude rigid fiberoptic techniques, and flexible bronchoscopic intubation under gen­ eral anesthesia may be more difficult in the presence of dis­ torted anatomy and decreased mobility of the airway structures. Langeron et al.37 reported failed blind intubation through the ILMA in patients who had cervical radiation. However, Ferson et al.36 reported successful bronchoscopic intubation through the ILMA in patients who had airway changes secondary to radiotherapy. Tremblay et al. 50 identified only high Cormack­ Lehane grade with direct laryngoscopy, high upper lip bite test score, and short sternothyroid distance to be predictors of difficult intubation with the Glidescope video-laryngoscope. Aziz et alY reviewed 2004 GlideScope intubations in patients undergoing general anesthesia at two institutions. The authors identified four preoperative predictors significantly associated with failed GVL intubation: neck anatomy, thyromental dis­ tance, reduced cervical motion, and institution. Altered neck

anatomy due to previous surgery, mass, or radiation was found to be the strongest predictor of GVL failure. 47 This finding when combined with data demonstrating that radiation changes are also the strongest predictor of impossible mask-ventilation indicates the need for a carefully thought out plan for airway

41 9

420

Ai rway M a n a g e m e n t in the Operati n g Room

management in patients with altered anatomy due to radiation therapyY Successful intubation of a 32-year-old patient who had previous chemoradiation for rhabdomyosarcoma of the neck and laryngeal elevation surgery was reported using the Pentax Airway-Scope®.51 Successful intubation using the Airtraq® com­ bined with the flexible bronchoscope has also been described in a patient who had a difficult airway subsequent to "extensive radiation to the neck." 5 2 Airway examination revealed hardened neck structures, limited mouth opening, a fixed mandible, the neck in flexion, and reduced thyromental distance. Mandibular advancement was "impossible" and pharyngeal tissue rigidity was described. • Can a Surgical Airway be More Difficult in

This G roup of Patients?

Subcutaneous fibrosis in the neck can obscure surface ana­ tomical landmarks, obliterate tissue planes, and make a sur­ gical approach to the airway technically challenging (see Figure 36-2) . Percutaneous cricothyrotomy may fail in this set­ ting, and tracheotomy may require more time to complete and be associated with more bleeding.53 As an emergency surgical airway may be more difficult in patients with a history of neck radiation, this ultimate airway rescue technique may not secure the airway in a timely fashion, and this eventuality must be considered when the plan for airway management is made.33 • What Should be the Approach to Airway

Management in These Patients?

Neck radiation produces a wide spectrum of pathophysiology,33 and airway management of the patient following cervical or oral radiotherapy requires a careful airway assessment. The assessment should focus on the four "dimensions" of airway management as outlined by Murphy et al.,54 and be used to predict potential difficulty with ( 1 ) face-mask-ventilation, (2) ventilation using an extraglottic device, (3) tracheal intuba­ tion, and (4) surgical access to the airway. If mask-ventilation and intubation are both predicted to be difficult after radiotherapy, then the airway should be secured with the patient awake. Should general anesthesia be induced in this setting and mask-ventilation be inadequate, rescue ventilation by means of an LMA may also fail. 18 The use of an LMA after cervical radiotherapy may in fact be contrain­ dicated. 18 Furthermore, rescue by means of a surgical airway may also be difficult.33. s 3 Topical anesthesia of the upper air­ way has been reported to produce transient glottic obstruction resulting in a profound reduction in maximum inspiratory and expiratory flows in some normal subjects,55 and in the pres­ ence of preexisting airway compromise, an increase in resistance to gas Row may be poorly tolerated. 56 Complete obstruction has been reported during topicalization and instrumentation of the airway.53·57·58 However, awake bronchoscopic intuba­ tion, in general, maintains a wider margin of safety and has been said to be the recommended method in the patient with predicted difficult intubation post-radiotherapy. Nonetheless, extreme caution must be exercised in the presence of severe

airway obstruction if complete obstruction is to be avoided. 18·59 Following radiotherapy to the floor of the mouth and/or phar­ ynx, severe trismus may preclude oral intubation techniques, and in this setting awake nasal bronchoscopic intubation may be the most reasonable alternative. If mask-ventilation is predicted to be easy but intubation difficult, then bronchoscopic intubation under general anes­ thesia may be considered, although anatomic distortion and decreased tissue mobility can make bronchoscopic visualization more difficult. Bronchoscopic intubation via an ILMA has been successful in the presence of radiotherapy-induced changes to the airway.36 However, failure of blind intubation through the ILMA in this setting has been reported. 37 In the presence of anatomic distortion but when intubation is predicted to be possible, inhalation induction of general anes­ thesia may be a reasonable option.43 . s 6'60'61 When an adequate depth of general anesthesia has been achieved, intubation can be performed during spontaneous ventilation utilizing a curved or straight blade laryngoscope, an operating laryngoscope such as the tubular Lindholm scope, or a rigid bronchoscope.56·61 If intubation is not possible, tracheotomy can be performed under general anesthesia. Inhalation induction in the presence of airway compromise can however be difficult.56·6° Complete airway obstruction can occur and an emergency surgical airway may be required.56·60 Meticulous attention to detail is neces­ sary, in particular the maintenance of spontaneous ventilation and the avoidance of airway instrumentation until an adequate depth of general anesthesia is achieved. 56 The use of a nasal air­ way to alleviate obstruction at the level of the soft palate during inhalation induction may be helpful. 56 The 4th National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society (NAP4) reported 1 6 patients with head and neck pathology who underwent inhalation induction of anes­ thesia.62 In 12 of these patients, the spontaneous ventilation became more difficult and airway compromise and oxygen desaturation occurred. In 1 1 patients, spontaneous ventilation became impossible. Despite respiratory distress, airway obstruc­ tion, and hypoxemia, the patients did not "rapidly awaken" when airway compromise occurred. The audit concluded that inhalation induction in patients with head and neck pathology can and does fail and when this technique is used, there should be a clear rescue plan that does not assume that the patient will awaken.62 Patients who have an extremely compromised airway, severe stridor, gross anatomic distortion, or a larynx that cannot be visualized on endoscopy should undergo awake tracheotomy performed under local anesthesia. 56·60·61 • How Should This Patient's Airway be

Managed?

An anesthetic record from 2 years prior to this admission was available for review. Face-mask-ventilation had been recorded as " moderately easy'' and intubation had been achieved using a lighrwand on the third attempt. Difficult direct laryngoscopy was predicted based on the examination of the airway (Mallampati IV, reduced mouth opening, limited mandibular protrusion, decreased cervical

Ai rway M a n a g e m e n t of a Patient with a H i story of Ora l a n d Cervica l Rad iation Thera py

extension, woody induration involving the mandibular space) . The predicted ease of face-mask-ventilation was also uncertain due to the presence of the submandibular induration, reduced mandibular protrusion, and limited cervical extension. The recorded experience with face-mask-ventilation at the previous surgery is not reassuring. Ventilation by means of an LMA or other extraglottic device may be difficult as well in the presence of the existing anatomic distortion. Surgical access to the air­ way was not predicted to be difficult. An awake bronchoscopic intubation was planned. Routine monitors were attached and IV access established. No sedation was administered. Five percent lidocaine paste was applied to the posterior one-third of the tongue using a tongue depressor. An Alcove atomizer (see Chapter 3) was then used to administer 1 0 mL of 4% lidocaine via the right nostril and the mouth. An internal approach superior laryngeal nerve block was performed using Jackson forceps and cotton pledgers soaked in 4% lidocaine. The adult bronchoscope was then eas­ ily passed through the mouth into the trachea with the patient in the sitting position and using gentle tongue traction. A #8 . 5 endotracheal tube was then passed easily over the bronchoscope during maximum inspiration to widely abduct the vocal cords. The patient tolerated the intubation well. General anesthesia was then induced and bronchoscopy and mediastinoscopy per­ formed uneventfully.

POST- I NTU BATION CO N S I D E RATIONS • How Should This Patient be Extubated?

Severe post-extubation laryngeal obstruction due to laryngeal edema has been reported following hepatic resection in a patient who had previously undergone bilateral modified radical neck dissection and radiation therapy.63 However, laryngeal edema was j udged to be unlikely following this relatively brief surgical procedure in which the volume of intravenous fluid adminis­ tered was small. Furthermore, no evidence of airway obstruc­ tion existed preoperatively. If concern exists about pharyngeal or laryngeal edema, inspection of the pharynx and supraglottic larynx could be carried out by video-laryngoscopy or video­ laryngoscopy combined with flexible bronchoscopy prior to emergence. Consideration could also be given to extubation over a pediatric airway exchange catheter (AEC) being careful to keep the tip of the catheter above the carina. The patient was extubated fully awake in the semi-sitting position in the operating room immediately following surgery. The postoperative course was uneventful.

S U M MARY Radiotherapy to the head and neck can produce limited mouth opening, limited cervical spine extension, noncompliant fibrotic soft tissue in the floor of the mouth and pharynx, and alteration of laryngeal anatomy. It is the most significant clini­ cal predictor of impossible mask-ventilation33 and neck mass or radiation is an independent predictor of DMV combined with OL.35 Altered neck anatomy due to previous surgery, mass, or radiation is the strongest predictor of GVL failure.47 Direct

laryngoscopy, extraglottic device use, 18·36•37 and performance of a surgical airway may all be difficult following radiotherapy to the head and neck. Neck radiation changes should be a cause for concern during airway management.33 Airway management of the patient following cervical or oral radiotherapy therefore requires a careful airway assess­ ment focused on the prediction of DMV, difficult extraglot­ tic device utilization, difficult intubation, and difficult surgical airway. While complete obstruction has been reported during topicalization and instrumentation of the airway, awake bron­ choscopic intubation, in general, maintains a wider margin of safery and is the preferred method in the patient with predicted DMV and difficult laryngoscopic intubation post-radiotherapy. Patients who have an extremely compromised airway, severe stridor, gross anatomic distortion, or a larynx that cannot be visualized on endoscopy should undergo awake tracheotomy performed under local anesthesia.

REFERENCES 1 . Larson DL. Management of complications of radiotherapy of the head and neck. Surg Clin North Am. 1 986;66( 1 ) : 1 69- 1 82. 2. Dorr W. Chapter 13: Pathogenesis of normal-tissue side-effects. In: Joiner M, van der Kogel A, eds. Basic Clinical Radiobiology. 4th ed. London: Hodder Arnold; 2009: 1 69- 1 90. 3 . Wu CH, Hsiao TY, Ko JY, Hsu MM. Dysphagia after radiotherapy: endo­ scopic examination of swallowing in patients with nasopharyngeal carci­ noma. Ann Otol Rhino! Laryngol. 2000; I 09(3): 320-325. 4. Stone HB, Coleman CN, Anscher MS, McBride WH. Effects of radia­ tion on normal tissue: consequences and mechanisms. Lancet Oneal. 2003;4(9) : 529-536. 5 . Trotti A. Toxicity in head and neck cancer: a review of trends and issues. Intj Radiat Oncol Biol Phys. 2000;47 ( 1 ) : 1 - 1 2. 6. Vikram B. Complications of radiation therapy. In: Ossoff RH, Krespi YP, eds. Complications in Head and Neck Surgery. Philadelphia, PA: Saunders; 1 993:3 1 1 -3 1 9. 7. Parsons J, Mendenhall WM, Million RR. Complications of radiotherapy for head and neck neoplasms. In: Mark C Weissler MC, Pillsbury HC, eds. Complications of Head and Neck Surgery. New York, NY: Thieme Medical Publishers; 1 99 5 : 1 94-229. 8. Cooper JS, Fu K, Marks J, Silverman S. Late effects of radiation therapy in the head and neck region. lntJ Radiat Oneal Biol Phys. 1 995;3 1 (5): 1 1 4 1 - 1 1 64. 9. Gaitini LA, Fradis M, Vaida SJ, Somri M, Malatskey SH, Golz A. Pneumomediastinum due to venturi jet ventilation used during micro­ laryngeal surgery in a previously neck-irradiated patient. Ann Otol Rhino! Laryngol. 2000; I 09(5) : 5 1 9-52 1 . 1 0 . Weissler MC. Management o f complications resulting from laryngeal can­ cer treatment. Otolaryngol Clin North Am. 1 9 97;30 (2) :269-278 . 1 1 . Ichimura K, Sugasawa M, Nibu K, Takasago E, Hasezawa K. The sig­ nificance of arytenoid edema following radiotherapy of laryngeal carci­ noma with respect to residual and recurrent tumour. Auris Nasus Larynx. 1 997;24 (4) :39 1 -397. 12. Patterson JM, Hildreth A, Wilson JA. Measuring edema in irradiated head and neck cancer patients. Ann Otol Rhino! Laryngol. 2007; 1 1 6 (8) : 5 5 9-564. 13. Rancati T, Schwarz M, Allen AM, et a!. Radiation dose-volume effects in the larynx and pharynx. lnt J Radiat Oneal Biol Phys. 20 1 0;76 (3 suppl) :S64-S69. 14. Bae JS, Roh JL, Lee SW, et a!. Laryngeal edema after radiotherapy in patients with squamous cell carcinomas of the larynx and hypopharynx. Oral Oncol. 2 0 1 2;48 {9) :853-858. 15. Dorr W, Hendry JH. Consequential late effects in normal tissues. Radiother Oneal. 200 1 ; 6 1 (3) :223-23 1 . 1 6. Denham JW, Hauer-Jensen M . The radiotherapeutic injury-a complex 'wound'. Radiother Oncol. 2002;63{2) : 1 29- 1 4 5 . 1 7 . Fajardo L F. Morphology of radiation effects normal times. I n : Perez CA, Brady LW, eds. Principles and Practice of Radiation Oncology. 2nd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 1 992: 1 237- 1 24 1 . 1 8 . Giraud 0 , Bourgain JL, Marandas P, Billard V Limits o f laryngeal mask airway in patients after cervical or oral radiotherapy. Can J Anaesth. 1 997;44 ( 1 2) : 1 237- 1 24 1 .

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Ai rway M a n a g e m e n t in the Operati n g Room 1 9. Goldstein M, Maxymiw WG, Cummings BJ, Wood RE. The effects of antitumor irradiation on mandibular opening and mobility: a prospective study of 58 patients. Oral Surg Oral Med Oral Pathol Oral Radio! Endod. 1 999;88(3): 365-373. 20. Dijksrra PU, Kalk WW, Roodenburg JL. Trismus in head and neck oncol­ ogy: a systematic review. Oral Oncol. 2004;40(9) :879-889. 2 1 . Truong A, Truong DT. Retromolar fibreoptic orotracheal intubation in a patient with severe trismus undergoing nasal surgery. Can J Anaesth. 20 1 1 ; 5 8 (5) :460-463. 22. Mitral BB, Pauloski BR, Haraf DJ, et a!. Swallowing dysfunction-preven­ tative and rehabilitation strategies in patients with head-and-neck cancers treated with surgery, radiotherapy, and chemotherapy: a critical review. Int ] Radiat Oncol Bioi Phys. 2003;57(5) : 1 2 1 9- 1 230. 23. Reed AP, Frost EA. Radiation induced hypopharyngeal stenosis mas­ querading as the larynx: a case report. Middle East ] Anaesthesia!. 20 1 0;20 (5):73 1 -733. 24. Nageris B, Elidan J, Sichel JY. Aerodigestive tract obstruction as a late complication of radiotherapy. ] Laryngol Otol. 1 99 5 ; 1 0 9 ( 1 ) :68-69. 25. Stevens MS, Chang A, Simpson CB. Supraglottic stenosis: etiology and treat­ ment of a rare condition. Ann Otol Rhino! Laryngol. 20 1 3 ; 1 22(3):205-209. 26. Tobin HA. Radiation-induced pharyngeal stenosis. A report of two cases after planned postoperative radiation therapy. Arch Otolaryngol. 1 979; 1 05 (6) :362-363. 27. Ku PK, Tong MC, Tsang SS, van Hasselt A. Acquired posterior cho­ ana! stenosis and atresia: management of this unusual complication after radiotherapy for nasopharyngeal carcinoma. Am ] Otolaryngol. 200 1 ;22 (4) :225-229. 28. Zhou J, Jolly S . Obstructive sleep apnea and fatigue in head and neck cancer patients. Am ] Clin Oncol. 20 1 5 ;3 8 (4) : 4 1 1 -4 1 4. 29. Francfort JW, Smullens SN, Gallagher JF, Fairman RM. Airway compro­ mise after carotid surgery in patients with cervical irradiation. J Cardiovasc Surg (Torino). 1 989;30(6): 877-88 1 . 30. Lau D P, Lo YL, Wee J , Tan NG, Low WK. Vocal fold paralysis following radiotherapy for nasopharyngeal carcinoma: laryngeal electromyography findings. J Voice. 2003; 1 7 ( 1 ) :82-87. 3 1 . Sanguineti G, Adapala P, Endres EJ, et al. Dosimetric predictors of laryn­ geal edema. IntJ Radiat Oncol Bioi Phys. 2007;68 (3) :74 1 -749. 32. Rancati T, Fiorino C, Sanguineti G. NTCP modeling of subacute/late laryngeal edema scored by fiberoptic examination. Int J Radiat Oncol Bioi Phys. 2009;75 (3) : 9 1 5-923. 33. Kheterpal S, Martin L, Shanks AM, Tremper KK. Prediction and out­ comes of impossible mask ventilation: a review of 50,000 anesthetics. Anesthesiology. 2009; 1 1 0 (4) :89 1 -897. 34. Kheterpal S, Han R, Tremper KK, et al. Incidence and predictors of difficult and impossible mask ventilation. Anesthesiology. 2006; 1 0 5 (5 ) : 8 8 5-89 1 . 3 5 . Kheterpal S , Healy D , Aziz MF, et al. Incidence, predictors, and outcome of difficult mask ventilation combined with difficult laryngoscopy: a report from the multicenter perioperative outcomes group. Anesthesiology. 20 1 3; 1 1 9(6) : 1 360- 1 369. 36. Ferson DZ, Rosenblatt WH, Johansen MJ, Osborn I, Ovassapian A. Use of the Intubating LMA-Fastrach in 254 patients with difficult-to-manage airways. Anesthesiology. 200 1 ;9 5 (5) : 1 1 7 5- 1 1 8 1 . 37. Langeron 0 , Semjen F, Bourgain JL, Marsac A, Cros AM . Comparison of the intubating laryngeal mask airway with the fiberoptic intubation in antic­ ipated difficult airway management. Anesthesiology. 200 1 ;94(6): 968-972. 38. Siddiqui S, Seer E, Chan WY. The use of laryngeal mask airway supreme in rescue airway situation in the critical care unit. Singapore Med ]. 20 14; 5 5 ( 1 2) :e205-e206. 39. Singh M, Srivastava M, Kapoor D. AMBU-LM Aura Once' in manage­ ment of difficult airway in post-radiotherapy oral burns patient admitted in intensive care unit. ] Anaesthesia! Clin Pharmacal. 2 0 1 4;30(4) : 574-575. 40. Ramachandran SK, Mathis MR, Tremper KK, Shanks AM, Kheterpal S . Predictors and clinical outcomes from failed laryngeal mask airway unique: a study of 1 5,795 patients. Anesthesiology. 20 1 2; 1 1 6(6) : 1 2 1 7- 1 226. 4 1 . Tomioka T, Ogawa M, Sawamura S, Hayashida M, Hanaoka K. A case of post-radiation therapy patient with difficulty in intubation unexpected preoperatively. Masui. 2003;52(4):406-408. 42. Yaney LL. Double-lumen endotracheal tube for one-lung ventila­ tion through a fresh tracheostomy stoma: a case report. AANA ]. 2007;75(6) :4 1 1 -4 1 5 . 43. lseli TA, lseli CE, Golden JB, et a!. Outcomes of intubation in difficult air­ ways due to head and neck pathology. Ear Nose Throat]. 20 1 2 ; 9 1 (3) : E 1 -E5. 44. Delbridge L, Sutherland J, Somerville H, Steinbeck K, Stevens G. Thyroid surgery and anaesthesia following head and neck irradiation for childhood malignancy. Aust N Z J Surg. 2000;70 (7) :490-492.

45. Huitink JM, Balm AJ, Keijzer C, Buirelaar DR. Awake fibrecapnic intuba­ tion in head and neck cancer patients with difficult airways: new findings and refinements to the technique. Anaesthesia. 2007;62(3) :2 1 4-2 1 9 . 46. Arne J, Descoins P, Fusciardi J, et al. Preoperative assessment for difficult intubation in general and ENT surgery: predictive value of a clinical mul­ tivariate risk index. Br J Anaesth. 1 998;80(2) : 1 40- 1 46. 47. Aziz MF, Healy D, Kheterpal S , Fu RF, Dillman D, Brambrink AM . Routine clinical practice effectiveness of the glidescope in difficult airway management: an analysis of 2,004 Glidescope intubations, complications, and failures from two institutions. Anesthesiology. 2 0 1 1 ; 1 1 4 ( 1 ) : 34-4 1 . 48. Hung OR, Stewart RD. Illuminating stylette (lightwand) . In: BenumofJL, ed. Airway Management: Principles and Practice. St. Louis, MO: Mosby; 1 996:342-352. 49. Sanchez AF, Morrison DE. Retrograde intubation. In: Hagberg CA, ed. Handbook of Difficult Airway Management. Philadelphia, PA: Churchill Livingstone; 2000: 1 1 5- 1 48. 50. Tremblay MH, Williams S, Robitaille A, Drolet P. Poor visualization dur­ ing direct laryngoscopy and high upper lip bite test score are predictors of difficult intubation with the GlideScope videolaryngoscope. Anesth Analg. 2008; 1 06(5): 1 495-500. 5 1 . Sunohara M, Okada T. An adult case of difficult intubation caused by late complications of radiotherapy for pediatric neck malignancy, as well as a later laryngeal elevation surgery. Masui. 20 1 5 ;64 ( 1 2) : 1 269- 1 272. 52. Madoc AA. Use of the airtraq with a fibreoptic bronchoscope in a difficult intubation outside the operating room. Can]Anaesth. 2008;5 5 (8 ) : 5 6 1 -562. 53. Ho AM, Chung DC, To EW, Karmakar MK. Total airway obstruction during local anesthesia in a non-sedated patient with a compromised air­ way. Can ]Anaesth. 2004; 5 1 (8): 838-84 1 . 54. Murphy M , Hung 0 , Launcelott G , Law JA, Morris I . Predicting the dif­ ficult laryngoscopic intubation: are we on the right track? Can J Anaesth. 2005 ;52(3) :23 1 -235. 5 5 . Liistro G, Stanescu DC, Veriter C, Rodenstein DO, D'Odemont JP. Upper airway anesthesia induces airflow limitation in awake humans. Am Rev Respir Dis. 1 992; 1 46(3) : 5 8 1 -5 8 5 . 56. Mason RA , Fielder CP. The obstructed airway in head and neck surgery. Anaesthesia. 1 999; 54 (7) :625-628. 57. McGuire G, ei-Beheiry H . Complete upper airway obstruction during awake fibreoptic intubation in patients with unstable cervical spine frac­ tures. Can ] Anaesth. 1 999;46 (2) : 1 76 - 1 7 8 . 5 8 . Shaw I C , Welchew EA , Harrison BJ, Michael S . Complete airway obstruc­ tion during awake fibreoptic intubation. Anaesthesia. 1 997;52(6) : 5 82-5 8 5 . 59. Ovassapian A . Flexible fiberoptic tracheal intubation. I n : Hagberg CA, ed. Handbook ofDifficult Airway Management. Philadelphia, PA: Churchill Livingstone; 2000:83- 1 1 4. 60. Wong DT, McGuire GP. Management choices for the difficult airway (author reply) . Can J Anaesth. 2003; 50:624. 6 1 . Deam R, McCutcheon C. Management choices for the difficult airway. Can J Anaesth. 2003;50(6):623-624; author reply 624. 62. Patel A, Pearce A, Pracy P. Head and neck pathology. NAP4 Report and

Findings ofthe 4th National Audit Project ofthe Royal College ofAnaesthetists. 20 1 1 ;4: 1 43- 1 5 1 , 1 54. 63. Burkle CM, Walsh MT, Pryor SG, Kasperbauer JL. Severe postextuba­ tion laryngeal obstruction: the role of prior neck dissection and radiation. Anesth Analg. 2006; 1 02 ( 1 ) : 322-325.

SELF - EVALUATION QU ESTIONS 36. 1 . Which o f the following i s NOT true i n the airway man­ agement of a patient with a history of radiotherapy to the head and neck? A. surgical airway should be uncomplicated B. limited mouth opening may preclude rigid fiberoptic intubating techniques C. fibrosis of the structures of the floor of the mouth can make direct laryngoscopy difficult D. a decrease in vocal cord mobility may interfere with glottic cannulation

Ai rway M a n a g e m e n t of a Patient with a H i story of Ora l a n d Cervica l Rad iation Thera py

E. in the presence of anatomic distortion of the airway, the light-guided technique using a lighrwand is best avoided 36.2. The most significant clinical predictor of impossible mask-ventilation is:

36.3. Anatomic and pathophysiologic changes associated with head and neck radiotherapy include: A. edema B. fibrosis C. trismus

A. neck radiation changes

D. xerostomia

B. obesity

E. all of the above

C. obstructive sleep apnea D. presence of a beard E. male sex

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Airway Manage ment in Penetratin g Nec k Injury Jan R. Morris

CAS E PRESENTATION

424

I NTRO DUCTION .

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C L I N ICAL ASS ESSMENT . . . . . . . . . . . . . . . . . . . . . . . . . . 428 AI RWAY MANAGEM ENT . . . . . . . . . . . . . . . . . . . . . . . .

430

OTH ER CO N S I D ERATIONS . . . . . . . . . . . . . . . . . . . . . . .

434

S U MMARY . . . . . . . . . . . .

437

SELF-EVALUATIO N Q U ESTI O N S .

439

(NRFM) . The patient was immobilized on a spine board and transported to the emergency department (ED) . Transport time was 20 minutes. On arrival in the ED the patient was awake and responded appropriately. Vital signs were: BP 1 40/90 mm Hg, HR 98 beats per minute, RR 26 breaths per minute. Sa0 was 98% on 2 NRFM. He was hoarse, had scant hemoptysis, and complained of pain in the anterior neck and left scapular area. Air could again be appreciated escaping from the neck wound. There was minimal bleeding. Subcutaneous (SC) emphysema was palpa­ ble in the anterior neck but no hematoma was detected. No exit wound was identified. Air entry was decreased on auscultation of the left chest. The Glasgow Coma scale was 1 5 and there were no neurologic deficits. The remainder of the examination was unremarkable.

CASE PRESENTATION A previously healthy 30-year-old male was shot at close range with a low caliber hand gun. A 9 1 1 call was placed immedi­ ately and paramedics were on the scene within 1 0 minutes . The victim was fully awake and cooperative. There was a sin­ gle gunshot entrance wound in the midline at the level of the thyroid cartilage (Figure 37- 1) . The entry wound was about 5 mm in diameter and air was noted to be escaping from it. There was minimal bleeding. The patient complained of pain in the area of the anterior neck and the left scapula. He also complained of dyspnea and coughed up scant bloody sputum. He had no allergies, was on no medications, and was previ­ ously healthy. Vital signs at the scene were: BP 1 40/60 mm Hg, HR 90 beats per minute, RR 22 breaths per minute. Oxygen satu­ ration (Sa0 ) was 97% and the Glasgow coma scale was 1 5 . 2 One intravenous cannula was placed in each upper extremity and oxygen was administered by non-rebreathing face mask

F I G U R E 37- 1 . Th i rty-year-o l d m a l e with g u n s hot wou n d of the neck.

Ai rway M a nagement i n Pe netrat i n g Neck I nj u ry

I NTRODUCTION • How Common Is Penetrating Neck

I nj ury (PNI)?

PNI has been reported to occur in 0.98% to 1 0% of all trauma patients1·6 and in 0.4% to 5% of major penetrating rrauma.7 Up to one-third of PNis are accompanied by other moder­ ate to severe injury. 1 Not all PNis involve viral structures. In a review of 26 reported series with a total of 4 1 93 patients with PNI, there were 1 2 8 5 vascular injuries (3 1 %) , 3 3 1 laryngotra­ cheal injuries (8%), and 354 digestive (pharyngeal and esopha­ geal) injuries (8.4%) .8 Others have reported vascular injury in 1 3 .3% to 37% of PNis,3·9-13 aerodigestive tract injury in 5% to 1 8 . 5%,5'9'1 1'13" 15 and esophageal injury in 0.9% to 9.6%.9•1 2 ·14·16 Pharyngoesophageal injury has been reported in 8% and 8.9% of PNis, 1 1'13 and spinal cord injury in 3 .2%4 and 6.7% . 1 0 The incidence of unstable cervical spine injury after penetrating neck trauma has been reported to be 0.4%.4 Approximately 1 6% of gunshot wounds (GSWs) to the neck and 1 4% of stab wounds (SWs) are associated with a hemo/pneumothorax.10·17 • What Is the Mortality Associated

with PNI?

Th e mortality associated with PNI has been reported i n mul­ tiple series and reviews to be between 0% and 1 7%1 .4-6·8-12· 18·29 with most of the fatalities resulting from vascular injury. 1.5·11 Two series of patients with PNI have reported the mor­ tality associated with vascular injury to be 0%13 and 2.2%.10 However, a mortality of 1 0% to 30% and approaching 50% has also been quoted.3·19·30 In a review of 1 1 series with a total of 1 5 84 cases, Asensio et al.8 reported an average calculated mortality from penetrating carotid injury of 1 7%. The mortality associated with penetrating laryngotracheal trauma has been reported to be 1 3 . 5%,31 3 . 5%,32 0%,13 and 1 1 . 5%.33 However, a mortality of 20%6·34 to 40%31 has also been quoted. The average calculated mortality for cervical esophageal wounds, most of which were penetrating, has been reported to be 1 0%.8 An increase in mortality has been observed with delayed diagnosis.3 A mortality of22% has also been quoted for penetrating pharyngoesophageal injuries.6 A mortality associated with aerodigestive tract injury of 1 3% has also been reported.35 The mortality associated with PNI also varies with the mech­ anism of injury. 2 8 The mortality associated with high-velocity bullet wounds is greater than that associated with low-velocity bullet wounds which is greater than that associated with SWs. 2 8 A mortality of 87% has been quoted for close range shotgun wounds (SGWs) .36 • Why Is Knowledge of the Anatomy

of the Neck I m porta nt in PNI?

The anatomy of the neck i s complex with multiple viral structures in close proximity enveloped in right fascial com­ partments. 5' 17 No other region of the body contains so many vital structures in such a confined space. Penetrating inj ury

F I G U R E 37-2. The th ree a nato m i c zo nes of the neck.

to the aerodigestive tract, major vascular structures, and the spinal cord can be life threatening.9 Optimal evaluation and management requires a thorough knowledge of the local anatomy. 17 ' 37 The neck can be defined as that area located between the lower margin of the mandible and the superior nuchal line of the occipital bone superiorly, and the suprasternal notch and the upper border of the clavicles inferiorly.37 For the pur­ pose of classification of PNI, the neck has been divided into three anatomic zones (Figure 37-2)9·37 based on surgical acces­ sibility to the underlying vasculature and aerodigestive tract structures. 2 Although Monson and others38-41 have described the sternal notch as the boundary line between zones I and II, multiple other authors consider zone I to extend from the level of the clavicles and sternal notch to the cricoid carti­ lage, 1·3·7·9•10·13·17·34·37.42 -44 and zone II to extend from the level of the cricoid cartilage to the angle of the mandible. Zone III extends from the angle of the mandible to the base of the skull. Although the three zones of the neck have been said to refer to the area anterior to the sternocleidomastoid mus­ cles,9 posterior neck structures have also been included in this classification.9•37 The structures in zone I include the aortic arch, proximal carotid arteries, vertebral arteries, subclavian vessels, innomi­ nate vessels, apices of the lung, esophagus, trachea, brachial plexus, thoracic duct, and spinal cord (Figure 37-3) . Important structures in zone II include the common, internal, and exter­ nal carotids, the jugular veins, the larynx, the hypopharynx, and the spinal cord3·9•37 (Figure 37-4) . Important structures in zone III include the distal cervical, petrous, and cavernous por­ tions of the internal carotid arteries, the vertebral arteries, the external carotid arteries and their major branches, the jugular veins, the prevertebral venous plexus, the pharynx, the spinal cord, and the facial nerves3·9·37 (Figure 37-5) . Th e location o f the external wound does not necessarily cor­ relate with the location of the underlying injurr and the site of the wound itself is no longer felt to be a reliable indicator of the presence of an injury, or the structures inj ured. 1 1 The relevance of the zone classification in the modern management

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Ai rway M a n a g e m e n t in the Operati n g Room

H u merus

Subclavian a. Esophag u s

B rac h i a l plexus

Apex of l u n g

Tl vertebra

Rib Sca p u l a Deltoid m .

S p i n a l cord S u bsca p u l a r i s m. S p l e n i u s ce rvicis m.

I nfra s p i n atus m .

F I G U R E 37-3. Anato m i c structu res i n Zo ne I of the neck a s seen i n tra n sverse sect i o n .

:� Sternohyoid m. ---..,...-----:•

Epiglottic cartilage -----: La rynx ----

-::!11111.: 11 __; : �-=----- La ryngeal fat pad �--- Thyroid ca rti lage :=-:---- Arytenoid carti lage t-=:---- Common ca rotid a .

La ryngopharynx --� I nternal j u g u l a r v. ---+ Sternocleidomastoid m. ----J C4 vertebra ------:*'

F I G U R E 37-4. Anato m i c structu res i n Zone I I of the neck a s seen i n tra n sverse section.

of PNI has been questioned and a "no zone" approach has been advocated. 44 The platysma, a thin superficial muscular sheet enclosed by the superficial fascia of the neck has often been cited as an important anatomical landmark in the determination of whether a penetrating neck wound is superficial or deep.3·37 Penetration of the platysma raises the potential of injury to a vital structure, and has been used as an indication for neck exploration. Deep to platysma is the deep cervical fascia which is subdivided into the investing, pretracheal, and prevertebral lay­ ers.3 These fascial layers play an important role in the clinical presentation and complications following penetrating trauma. 17 The fascial compartments of the neck can limit external hemor­ rhage, but when bleeding occurs within these closed compart­ ments, airway compression and distortion can be precipitated (Figure 37-6) .

• What D o "Selective" a n d "Mandatory"

Neck Exploration Mean?

Penetrating injuries i n zones I and I I I present complex diag­ nostic and therapeutic challenges. 5 Management of pen­ etrating injury to zone I is complicated by difficult surgical exposure and difficult proximal control of bleeding vessels.3 Penetrating inj ury to zone III is similarly complicated by dif­ ficult surgical exposure and distal control of bleeding vessels.3 Operative intervention for inj ury in zones I and III has tra­ ditionally been selective, based on physical examination and radiologic findings.37 The surgical management of penetrating injury to zone II has been controversial. Some authors have advocated man­ datory exploration for wounds that penetrate the platysma, whereas others recommend a more selective approach to surgi­ cal exploration due to high negative exploration rates using the

Ai rway M a nagement i n Pe netrat i n g Neck I nj u ry

Depressor a n g u l i oris m . ----

Pa rotid g l a nd ---..... Digastric m. ---�--::::.,�' External ca rotid a . --�--, I nterna l j u g u l a r v. ----41 (3 vertebra ----

....='-'"�.-':---- Pharynx '--....� .:, •-:---- Pharyngeal constrictor m. �,_.�-- I nterna l ca rotid a . �-�-- Retro m a n d i b u l a r v.

-�-- S p i n a l cord -;.---- Sternocleidomastoid m .

-----::...Splenius capitis m . .__ '------:f--- Sem i s p i n a l i s capitis m .

F I G U R E 3 7 - 5 . Anato m i c structu res i n Zone I l l o f the neck a s s e e n i n tra n sverse sectio n .

F I G U R E 37-6. T h e fa sci a l co m p a rtme nts o f the n e c k a s s e e n i n tra n sverse sect i o n .

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Ai rway M a n a g e m e n t in the Operati n g Room

mandatory approach. 10·13·16'18' 20-23·2 5-2 8 ,45-51 Mandatory explora­ tion was considered the standard of care for several decades after World War II.5 This practice has now been abandoned by most trauma centers and replaced by selective nonoperative management based on the clinical examination and appropriate investigations. 1 7 There is now strong evidence that the clinical exam, preferably according to a written protocol, is very reliable in identifying highly suspecting significant injuries17 and can be used to triage patients directly to the OR, to observation, or to appropriate investigation. 2 Selective exploration is currently the standard of care.5 2 Penetrating neck trauma most commonly occurs in zone II 17· 29·36 and requires emergency airway intervention in about one-third of cases. 29 In a series of 223 patients with PNI, Demetriades et al. 10 reported zone II injury in 47%, zone I inj ury in 1 8%, and zone III injury in 1 9% . More than one zone was involved in 1 6% . Inaba et al. 2 reported zone II injury in 3 8 .2%, zone I injury in 1 6.9%, and zone III injury in 1 6% in a series of 453 PNis. Multiple zones were involved in 28%. Two smaller series reported zone II injury in 43% to 64%, zone I injury in 1 6% to 1 7%, and zone III injury in 20% to 27%. 5·9 Soliman et al.5 reported injuries in multiple zones in 1 3%. In two series with predominantly SWs, most injuries occurred in zone I (4 1 o/o-44%) , followed by zone II (28o/o-29o/o) , and zone III (7%-27%) . 1 153 In the series reported by Madsen et al. , 1 1 76% o f the patients sustained wounds to the anterior triangle of the neck. Wounds in the anterior and lateral aspects of the neck produce airway compromise more often than those in the pos­ terior region. 54 Most SWs are to the left side of the neck, pre­ sumably due to the predominance of right-handed assailants. 17 • What Are the Mechan isms of I nju ry

in Penetrating Neck Trauma?

Eleven to 64% of PNis that penetrate the platysma have been reported to be caused by GSWs, 29% to 89% by SWs, and 0.9% to 6% by SGWs . 1 ,2 ·5·9-1 1'13 SWs produce a more predict­ able pattern of inj ury than do GSWs.36 GSWs produce tissue destruction that is dependent on the kinetic energy of the projectile, which is a function of its veloc­ ity.37 However, the transfer of kinetic energy is not the only determinant of tissue wounding.55 Tissue disruption depends as much on the shape, size, construction, and mass of the pro­ jectile as on its velocity.55'56 The pathophysiology of GSWs is complex and high-velocity projectiles do not necessarily cause more tissue damage than lower-velocity projectiles.56·57 The def­ inition of high velocity is also imprecise. 5556 Caliber refers to the diameter of the projectile. 55 The projectile produces a crush effect on tissue that it contacts (the permanent cavity) and a stretch effect on tissue surrounding the missile path (the tem­ porary cavity) produced by radial pressure waves which follow the penetrating projectile and impel the walls of the permanent cavity radially outwards.55•56·58·59 The volume of the permanent cavity is influenced by the yaw or tumbling, deformation, and fragmentation of the projectile. 55 The volume of the temporary cavity, in general, increases with the velocity of the projectile, and increases if the projectile tumbles or fragments.60 The effect of temporary cavitation is clinically variable and will depend

on the elasticity of the tissue affected as tissue planes are sep­ arated and tissues are displaced and stretched beyond elastic limits.55·57·59 Inelastic tissues such as liver are more susceptible to disruption by the temporary cavity than flexible tissue such as muscle.57·59 When bullets strike bone they can also ricochet, fragment, and deviate to make the resultant wound unpredict­ able and more extensive. 57 The site of the entry wound should be identified as well as the exit wound (if present) , and consid­ eration should be given to the path of the projectile.3 GSWs are more likely to cause vascular, aerodigestive, and neurologic inju­ ries than are SWs (73% vs. 3 1 %) .3·10 In a prospective series of PNis, GSWs were three times more likely than SWs to cause a large hematoma (20.6% vs. 6.7%) ; twice as likely to be associ­ ated with hypotension on admission ( 1 3.4% vs. 7.9%) ; twice as likely to cause a vascular inj ury (26.8% vs. 1 4. 6%) ; twice as likely to injure aerodigestive structures (7.2% vs. 3.4%) ; and 1 3 times more likely to cause spinal cord injury ( 1 3.4% vs. 3.4%) . 10•17 Overall approximately 35% to 45% of GSWs and 20% to 23% of SWs to the neck produce significant injuries to vital structures. 1 7·36·61 Transcervical GSWs (those that cross the midline) are more likely to inj ure vital structures than GSWs that do not cross the midline.3' 24 Seventy-three percent of tran­ scervical GSWs are associated with significant injuries to vital structures. 1 7·62 For this reason, mandatory exploration of tran­ scervical wounds has been recommended,63 while others con­ tinue to recommended a selective approach. 17·24·62 PNI can produce airway compromise as a result of blood and debris in the airway lumen, laryngotracheal injury with obstruction and air leak, and external compression by hema­ toma, edema, or SC emphysema. 1754 Spinal cord injury can also cause respiratory distress. Airway management is guided by clinical presentation.6

CLIN ICAL ASSESSMENT • What Are the Essential Elements

of the Clin ical Eva luation of PNI?

Historically, physical examination o f a PNI was considered to be unreliable unless hard signs of injury were present. 1 However, more recently it has been shown that a structured clinical exam­ ination can be used to triage patients regardless of the zone of injury. 2 Patients can be categorized into those with hard signs, soft signs, and no signs of vascular or aerodigestive injury. 2 The initial evaluation should follow the standard ABCs of resuscita­ tion, followed by a systematic, rapid, and thorough secondary survey.3 The primary survey should identify or rule out airway obstruction, tension pneumothorax, major active bleeding, spinal cord injury, and ischemic brain injury. 1 7 The secondary survey is directed to the identification of signs and symptoms of occult vascular injury, occult laryngotracheal injury, pharyn­ goesophageal injury, cranial and peripheral nerve injuries, and small pneumothoraces.17 Presence of "hard' signs of vascular or laryngotracheal injury including an expanding or pulsatile hema­ toma, severe active bleeding, hemorrhagic shock unresponsive to IV fluids, absent or diminished peripheral pulse, bruit or thrill in the area of injury, massive hemoptysis or hematemesis, air bubbling through the wound or airway compromise, mandates

Ai rway M a nagement i n Pe netrat i n g Neck I nj u ry

urgent operative intervention, 2 ·3•5•9·17•2 9•36·37•64 and airway con­ trol. Neurologic deficit and evolving stroke have also been con­ sidered to be hard signs of injury.5•36 In the hemodynamically stable patient without airway com­ promise who has "soft' signs of injury further diagnostic evalu­ ation of the aerodigestive tract, the vasculature, and the nervous system can be undertaken. 2 •3 Patients with "no signs" of inj ury other than the SW or GSW, and who are asymptomatic can be observed for a minimum of 24 hours. 2 Observation for 24 to 48 hours 1 1 ·30•5 2 and serial examination every 6 to 8 hours during the period of observation has been recommended.5 2 "Soft signs" which are suspicious for but not diagnostic of vas­ cular inj ury include small to moderate sized non-pulsatile and non-expanding hematomas, minor bleeding or pulsatile bleed­ ing that has stopped, mild hypotension that has responded to fluid resuscitation, and proximity wounds. 2 '5'175 2 Some authors have considered a radial pulse deficit, and the presence of a bruit or thrill36 or altered neurological status30 to be soft signs. Air embolism is possible in the presence of venous injury.3 Abrupt onset of a stroke type syndrome may herald vascular interruption, inj ury-induced thrombosis, or traumatic carotid or vertebral arterial dissection. After PNI the incidence of venous inj ury has been reported to be higher ( 1 8%-20%) than arterial injury ( 1 2%-1 3%).65 However, carotid injury has also been reported to occur in 4% to 1 5% of PNis and may account for 20% to 80% of all cervical vascular injuries. 17 The reported mortality after penetrating carotid artery injury has been reported to be as high as 66% . 1 7 Approximately 3% of patients with soft signs of vascular injury require a therapeu­ tic operation.17 Physical examination alone has been reported to be a reliable indicator of clinically significant vascular injury. 2 ·9•17•3053•64·66·67 In a retrospective review, Jarvik et al.67 found no statistically significant difference between the sensitiv­ ities of clinical examination and angiography. In a review of 1 4 5 cases o f PNI, Sekharan e t al.68 found that o f the 1 1 4 patients without hard signs of vascular injury, only one required opera­ tive repair. Azuaje et a!. 69 reported that physical examination alone had a 93% sensitivity and 97% negative predictive value (NPV) for vascular injury in a series of 2 1 6 patients. Similarly, Demetriades et al. 1 0 reported that none of 1 60 patients without clinical signs of vascular inj ury had serious vascular injury that required treatment. Thoma et al. 1 3 concluded that the absence of clinical signs and symptoms reasonably excluded vascular inj ury in their series of 203 patients. Conversely, in a prospec­ tive study of 59 patients with a GSW to the neck, Mohammed et aU0 found physical examination alone to have a sensitivity of 57%, a specificity of 53%, a positive predictive value (PPV) of 43%, and an NPV of 67%. Ten patients without clinical signs of vascular injury in fact had vascular injury?0 The severity of the injuries identified was not defined. In a series of 453 PNis, 8.6% had hard signs of vascular or aerodigestive injury, and 89.7% of these patients had a clinically significant injury requiring intervention. The remainder had soft tissue bleeding that required extensive surgical wound care. 2 One hundred and eighty-nine patients (4 1 .7%) had no signs of vascular or aerodigestive tract injury, and no injury was detected during observation and follow-up. Two hundred and twenty­ five patients underwent multidetector computed tomographic

angiography (MDCTA) . Thirty-nine of these patients under­ went MDCTA for proximity of the trajectory only, and all of these were negative. Twenty-eight injuries were detected in 22 of the 1 86 patients with soft signs of injury. Twenty-one of these patients required surgical or interventional radiology treatment. 2 Hematoma is the most common sign of vascular injury, fol­ lowed by shock and external bleeding.9 As mentioned above, bleeding within the compartmentalized spaces of the neck can produce insidious displacement and distortion of the air­ way without external evidence. Airway obstruction can occur precipitously following a period of apparent quiescence, and airway control can be difficult. 29 For this reason, any evidence of direct vascular injury to the neck has been said to be j ustifica­ tion for early endotracheal intubation. 2 9 The signs and symptoms of aerodigestive injury include hoarseness or dysphonia, stridor, SC emphysema or crepitance, dyspnea, dysphagia, hemoptysis, odynophagia, hematemesis, tenderness on palpation of the larynx, and air bubbling from the wound. 35·9· 11 Decreased breath sounds may be due to a hemothorax or pneumothorax.3 Aerodigestive tract injuries can be subdivided further into laryngotracheal and pharyngo­ esophageal injuries.5 In the setting of PNI, laryngotracheal inju­ ries are usually readily apparent.5 All 1 5 patients in the series reported by Soliman et al.5 who had clinically significant injuries to the aerodigestive tract met the criteria for immediate explora­ tion. The only "hard' clinical sign diagnostic of laryngotracheal injury is air escaping from the neck wound. 14·17 Air bubbling through the neck wound, massive hemoptysis or hemateme­ sis, or respiratory distress/airway compromise are indications for emergency surgical exploration. 2 '17'36 "Soft' signs are suspi­ cious but not diagnostic of significant injury and include minor hemoptysis, dysphonia/hoarseness, dyspnea, agitation, and SC emphysema?·5•17'36 Soft signs are present in approximately 1 8% of PNis and these patients require further investigation to iden­ tifY significant injuries that require repair. 17 Approximately 1 5% of patients with soft signs have a significant laryngotracheal injury.17 SC emphysema, found in 7% of patients with PNI, is the most common soft sign and may be due to laryngotracheal injury, esophageal injury, or associated pneumothorax.5·17·36 In approximately 1 5% of cases, no source of the SC emphysema is found and it is presumed that the air entered through the wound.17•36 Hoarseness is an indication of significant airway injury until proven otherwise.34 Demetriades et al. 14 reported that SC emphysema (clinical or radiological) was almost always present in penetrating aerodigestive tract injuries and SC crepi­ tus was the most common finding reported by Grewal et al.32 in a series of 57 patients with penetrating laryngotracheal trauma. An absence of signs or symptoms suggestive of aerodigestive trauma has been found to reliably exclude injuries requiring sur­ gical repair in a series of 1 52 patients. 1 0 Soliman et a!. 5 reported similar findings in a series of 1 63 patients. Emergency airway management has been required in 46% to 56% of patients with penetrating laryngotracheal injury.31·32 ·34 Pharyngoesophageal injury due to penetrating neck trauma can be occult and difficult to diagnose on physical exam. There are no hard signs diagnostic of injury. 1 7'36 Signs and symptoms suggestive of pharyngoesophageal injury include deep cervical

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Ai rway M a n a g e m e n t in the Operati n g Room

pain, chest pain, dysphagia, odynophagia, hematemesis or hemoptysis, SC crepitus/emphysema, a positive sip test (pain on swallowing a sip of water) , and retropharyngeal or medi­ astinal air on x-ray.35•17•36•5 2 "Soft" signs including odynopha­ gia, SC emphysema, hematemesis or hemoptysis are present in approximately 23% of patients with PNI and require evalua­ tion, but only 1 8% of patients with these findings have pha­ ryngoesophageal injury. 1 7 In the complete absence of these soft signs, it is highly unlikely that the patient has an injury requir­ ing treatment. 17 A thorough neurologic evaluation is necessary to detect or rule out penetrating injury to the central nervous system, cra­ nial nerves, or peripheral nerves. 3 Complete spinal cord transac­ tion above C5 can lead to respiratory arrest, and injury below C5 can cause respiratory distress.3 Injury to cranial nerve (CN) VII is manifested by facial weakness, CN XI by an inability to shrug the shoulders, and injury to CN XII by deviation of the tongue.3 Injury to cervical nerve roots C5-C7 will mani­ fest as sensory and motor deficit to the ipsilateral extremity. 2 Interruption of carotid or vertebral arterial flow can cause isch­ emic stroke.3 The identification of unstable cervical spine and spinal cord inj ury associated with PNI is important as immo­ bilization has implications for airway management as well as physical examination. It has been recommended that all patients with PNI be immobilized in a rigid cervical collar/1 despite the fact that unstable cervical spine inj ury in PNI due to SWs is exceed­ ingly rare. In the retrospective study by Rhee et al.,72 of 7483 patients with SWs, nine had cervical spine fracture, of whom six had spinal cord injury. Two additional patients had a cervical cord inj ury but no fracture. Three patients required stabiliza­ tion, none of whom were neurologically intact at presentation. All patients with cervical cord injury had obvious neurological deficit at the time of presentation. A GSW to the neck would need to disrupt the cervical spine in two of the three stabilizing columns to make the spine unstable and it is highly likely that the spinal cord would be inj ured as well in this setting.72 In the study by Rhee et al. cervical spine stabilization was required in 26 patients after GSW All patients with cervical spinal cord injury due to a GSW sustained the injury at the time of the GSW, and none had significant neurologic recovery despite stabilization. Cervical spine stabilization was required in four of 1 2 , 5 5 9 patients (0.03%) with a GSW who were neurologically intact.72 In a study reported by Klein et al. /3 33 of 1 83 patients with GSWs to the neck had cervical spine inj uries. However, only one of the 33 had a proven significant spinal injury with no neurologic findings on admission?3 The authors concluded that immobilization is essential for patients with GSWs to the neck until radiologic evaluation is complete?3 In a retrospec­ tive study by Medzon et al. /4 1 9 of 8 1 patients who had sus­ tained a GSW to the head or neck had documented cervical spine fractures. However, of the 65 patients who were alert and without neurologic deficits, only three had a fracture, none of which were unstable?4 Sixteen of the 1 9 patients with fractures required acute airway management. The authors were reluctant to recommend removal of collar immobilization based on their data. However, they note that the likelihood of an unstable fracture in an alert and examinable patient without neurologic

deficit is low.74 They went on to suggest that the decision to remove the collar or discontinue spinal precautions should be individualized, and when emergency airway control is required, it would be reasonable to remove obstructive devices to permit more expeditious treatment?4 In a retrospective review of 27 patients with PNI by Connell et al. /5 12 patients sustained a spinal cord inj ury, one due to a GSW and 1 1 from sharp weapons. Ten patients had obvious clinical evidence of spi­ nal cord injury and two were in traumatic cardiac arrest. The authors concluded that fully conscious patients with isolated penetrating trauma and no neurologic deficit do not require spinal immobilization. The retrospective review performed by Lustenberger et al.4 included 1 069 patients with PNI of whom 463 sustained a GSW and 606 a SW A cervical spine injury was diagnosed in 65 patients (6. 1 %), 56 due to GSW and nine due to SW Spinal cord injury occurred in 34 patients (3 .2%) , 32 in the GSW group and two in the SW group. The cervical spine injury was consid­ ered unstable in four patients (0.4%) , all following GSWs and all of whom had obvious neurological deficits or altered mental status at the time of admission. There were no cases of cervi­ cal instability after cervical SW The authors concluded based on their data that cervical spine immobilization has no role after SW to the neck. The incidence of unstable cervical spine injury after PNI is exceedingly low (0.4%) and all patients in their series had neurological deficits or altered mental status at presentation. Spinal immobilization may be of value after GSW to the neck, however, monitoring for hematoma and other life­ threatening complications must take priority.4 Based on the available evidence, it appears unlikely that iso­ lated PNI would produce an unstable cervical spine injury in the alert, examinable patient without a detectable neurologic deficit. Immobilization in this setting can interfere with airway management, can obscure findings on physical examination of the neck, and should only be considered when the mechanism of injury and/or physical findings suggest spinal cord involve­ ment. 6 The value of spinal immobilization by means of a collar in patients with PNI is questionable and may be harmful in some patients. 1 7 A 2007 review of PNI stated that it has no role in SWs to the neck and is of limited value in GSWs to the neck. 17 In the presence of coincidental blunt trauma, an altered level of consciousness, or neurologic deficit, immobilization is indicated. The patient presented here underwent cervical spine immo­ bilization. He had the only hard clinical sign of laryngotracheal injury on clinical examination, air escaping from the entry wound in the anterior neck. There were no signs of vascular or neurologic injury.

AI RWAY MANAGEMENT • What Airway Management Tech niq ues

Are Appropriate in PNI?

About 8% t o 1 Oo/o o f patients with PNis present with airway compromise, and approximately 30% of patients with laryngo­ tracheal injuries require emergency airway management. 17 The airway compromise may be due to direct trauma, severe edema,

Ai rway M a nagement i n Pe netrat i n g Neck I nj u ry

or external compression by hematoma. 17 Airway management is the first priority and can be intimidating and challenging even for the most skilled practitioners due to the coexistence of a potentially difficult airway and the need for rapid action. 1 · 29·76 In addition, the rarity of PNI means that the experience of any one practitioner in the management of this injury can be limited.77 The need for airway control must be determined and the time available to achieve that control must be estimated. There must be a willingness to act quickly despite incomplete information as a delay in intervention can be hazardous, 29 and there must be an ability to improvise and change plans under rapidly changing circumstances.34 Airway management deci­ sions must be based on the patient's specific injuries, existing signs of airway compromise, the anticipated clinical course and risk of deterioration, the need for transport, and the patient's overall condition and level of cooperation, as well as planned diagnostic and therapeutic interventions?· 29 On examination, evidence of inj ury to an air-containing structure in the neck (SC emphysema, stridor, dysphagia, odynophagia, respiratory distress), vascular inj ury (hematoma, active bleeding, shock, palpable thrill, carotid bruit, absent or diminished pulses) , and spinal cord injury (motor and sensory deficit) must be evalu­ ated. The presence of inspiratory stridor implies impending loss of the airway.65 The likelihood of difficult direct laryngoscopy must also be assessed. Emergency airway management may be necessary to secure a patent airway, in preparation for operative intervention, or as a part of airway evaluation in selective man­ agement of PNU Emergency airway control is indicated in the presence of airway obstruction, respiratory failure/distress, signs of significant airway injury, inability to protect the airway from aspiration, hemodynamic instability/ and hard signs of vascu­ lar injury that mandate emergency surgical intervention.6·9·37 Edema, SC emphysema, or hematoma can produce sudden air­ way obstruction following a period of relative quiescence, and anatomic distortion can make intubation or a surgical airway more difficult to perform. 2 9 The decision to observe a patient for impending airway com­ promise, or to secure the airway to avoid a difficult intubation in the presence of anatomic distortion, is a matter of clinical judgment. 2 9·76 This decision must be based on the evidence on clinical examination of significant vascular, aerodigestive tract, and neurologic injury, and recognize that if one chooses to "observe," complete airway obstruction may occur suddenly and be irreversible. The airway should be reevaluated frequently.65 If there is evidence of injury to an air-containing structure in the neck (larynx, trachea, pharynx, esophagus) , positive pres­ sure bag-mask-ventilation may be hazardous and can produce increased anatomic distortion, disruption, and airway obstruc­ tion.3·6 Laryngeal mask airways should not be used as their effi­ cacy is decreased in the presence of anatomic distortion and they may worsen the injury.78 Orotracheal intubation in the presence of laryngotracheal injury risks cannulation of a false passage, further disruption of damaged mucosa, and increased airway compromise. 14'79'80 If there is evidence of significant vas­ cular injury, airway management is indicated. 29 As mentioned above, a hematoma can expand in the deep tissue planes of the neck and airway compromise may proceed insidiously only to be followed by rapid and catastrophic deterioration. 2 9

The timing, place, and method of airway control depend on the type of neck injury, the cardio-respiratory condition of the patient, the available resources, and the experience and skills of the resuscitation team.3'10'17'81 Several investigators have reported experience with airway management in PNI. Shearer et al. 43 reviewed the records of 1 07 patients who required an artificial airway from a series of 282 patients admit­ ted with PNI. A surgical airway was the primary choice in 6%, RSI in 83%, awake bronchoscopic intubation in 7%, and blind nasal intubation in 4%. The success rates for these vari­ ous techniques were: primary surgical, 1 00%; RSI, 98%; awake bronchoscopic, 1 00%; and blind nasal, 75%. Eight of the 1 07 patients had laryngotracheal injuries (8%) and 38 patients had vascular injuries (3 5 . 5%) . RSI failed in two patients (2%) and a surgical airway was required. One blind nasal attempt failed (25%) and was followed by loss of the airway and death dur­ ing attempted cricothyrotomy. Tracheotomy was performed as the primary airway in three of the eight patients with laryngo­ tracheal injury. Of the nine patients who were hemodynami­ cally unstable, five underwent a tracheotomy or cricothyrotomy in the ED. The authors concluded that airway control can be achieved in most patients with a PNI by RSI or a surgical air­ way, and that a surgical airway should be strongly considered in patients who have wounds in proximity to the larynx who have stridor, dyspnea, hemoptysis, and SC emphysema.43 Mandavia et al. 8 2 conducted a retrospective study of ED incu­ bations in patients presenting with PNI at a level I trauma unit over a 3-year period. Seven hundred and forty-eight patients with PNI were evaluated in the ED, of whom 82 ( 1 1 %) required immediate airway management. Twenty-four of these 82 patients were excluded due to pre-hospital cardiac arrest or intubation. In the remaining 58 patients (45 GSWs, 12 SWs, 1 motor vehicle collision) , 39 underwent RSI with a 1 00% success rate. Thirty­ three patients required one attempt, four patients required two attempts, and two required three attempts. Oxygen desatura­ tion (less than 90%) occurred in two patients. Five uncon­ scious patients were intubated orally without paralysis, and two underwent emergency tracheotomy. Flexible bronchoscopic intubation was attempted by ENT residents in 12 patients and was successful in nine. The three remaining patients were suc­ cessfully intubated by RSI, although one patient required two attempts and experienced oxygen desaturation to 79%. Both patients who underwent emergency tracheotomy had GSWs and were unable to phonate properly. One of these patients had a laryngeal injury confirmed by endoscopic laryngoscopy prior to tracheotomy. Oral endotracheal intubation was the definitive technique in 47 of the 58 patients and was successful 1 00% of the time it was employed. The authors concluded that RSI was safe and effective in all of the cases in which it was attempted, and that practitioners with airway expertise should consider using RSI in the setting of PNI.8 2 Eggen and jorden38 reviewed the charts of 1 1 4 patients with penetrating injury that breeched the platysma. The mecha­ nism of injury was GSW in 59, SW in 39, SGW in seven, and miscellaneous in nine patients. Sixty-nine patients required intubation, of whom 26 were intubated urgently. Urgent air­ way control was considered necessary in the presence of acute

43 1

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airway distress, airway compromise from blood or secretions, extensive SC emphysema, tracheal shift, or severe alteration of mental status. Eight of the 26 urgent intubations were initially unsuccessful, and six of these required an alternative technique. Four of these were failed oral intubation, three of whom were subsequently managed via the open wound, and one via a tra­ cheotomy. Two of the six were failed nasotracheal intubations both of whom required emergency tracheotomy. Of the 26 patients who required urgent airway control, nine required a tracheotomy and five of these patients had diffuse SC emphy­ sema. Of the 98 patients with zone II injury, 22% required urgent airway control whereas all three patients with zone I injury, and five of 1 3 (38%) with zone III injury required urgent airway control. The authors noted that a variety of approaches to airway management have been documented to be success­ ful, and that no approach should be dismissed unless specific circumstances contraindicate it or make it technically impos­ sible.38 This study was published at a time when RSI was not widely practiced by emergency physicians. Bell et af.9 performed a retrospective analysis of 1 34 patients with PNI of whom 65 sustained wounds that violated the pla­ tysma. There were 3 1 patients with GSWs, 63 SWs, 1 3 flying glass injuries, and 1 5 who were impaled. Eight patients did not require airway management, except for the purpose of general anesthesia. Of the 59 patients who required emergency airway management, 48 were successfully intubated orally in the field. There were rwo failed intubations that required emergency tra­ cheotomy on arrival, and seven additional tracheotomies were performed for airway compromise.9 Tallon et al. 83 performed a retrospective review of the air­ way management of PNI in a Canadian tertiary care center and identified 1 9 patients over the 1 1 -year study period. Three patients were not intubated. Of the remaining 1 6, five were intubated in the pre-hospital setting, six in the ED, and five in the operating room (OR) . Eight patients were intubated awake and eight underwent RSI. No adverse airway-related outcomes were identified in either group.83 Thoma et al. 1 3 performed a prospective observational study of 203 patients with PNI who presented to Groote Schuur Hospital in Cape Town between July 2004 and July 2005. One hundred and fifty-nine patients presented with SWs and 42 with low-velocity GSWs. A vascular injury was identified in 27 patients, pharyngoesophageal injury in 1 8 , and an upper airway injury in eight. Four patients had a laryngeal injury and four had tracheal injuries. Twenty-five patients required surgical interven­ tion, and eight additional patients had endovascular procedures. Six patients underwent tracheotomy, four of whom had airway compromise associated with oropharyngeal injury. One of the patients with laryngeal injury required tracheotomy and one patient with a complete C4 spinal cord injury required long­ term ventilation. Patients with airway compromise and hemo­ dynamic stability were intubated either by oral endotracheal intubation or if that failed, emergency cricothyrotomy. However, there were no failed intubations requiring a surgical airway. The details of the technique of intubation were not provided. 1 3 Grewal et al. 32 retrospectively analyzed the records o f all patients admitted to a level I trauma center who required opera­ tive management for penetrating laryngotracheal injury over a

1 5-year period. Of the 57 patients with penetrating laryngo­ tracheal injury, 32 had sustained GSWs and 25 had sustained SWs. Five patients were hemodynamically unstable on arrival. Emergency airway management was required in 32 of the 57 patients. Oral endotracheal intubation was performed in 1 4, cricothyrotomy in three, and tracheotomy in 1 5 . Eight of the emergency tracheotomies were performed in the ED. Forty-four patients underwent tracheotomy in the course of their resusci­ tation and management. The authors concluded that endotra­ cheal intubation can be safely accomplished in selected patients with penetrating laryngotracheal injuries.3 2 They suggested that patients with minor to moderate laryngotracheal injury can be safely intubated whereas patients with major laryngeal injuries required individualized management. If the expertise required to perform tracheotomy in the ED is limited, then cricothy­ rotomy was felt to be the safest alternative.32 In a retrospective review of laryngotracheal trauma at two major hospitals between 1 996 and 2004, Bhojani et al. 3 1 iden­ tified 52 patients who had sustained penetrating laryngotra­ cheal injury. There were 26 GSWs and 24 SWs. Twenty-four of the 52 patients required an emergency airway. Endotracheal intubation was performed in 20, tracheotomy in three, and cri­ cothyrotomy in one. One patient, who was previously intubated, subsequently required emergency cricothyrotomy in the OR. Twelve of the patients who were intubated or who underwent cricothyrotomy required revision to tracheotomy. An additional seven patients required operative tracheotomy. The authors concluded that either routine intubation or a tracheotomy can be used to secure the airway.31 In a retrospective study of aerodigestive injuries of the neck, Vassiliu et al. 15 reviewed 1 562 patients with neck trauma and identified 998 patients who had sustained penetrating injury. There were 432 GSWs and 524 SWs during the 5-year study period. Blunt trauma produced aerodigestive inj ury in seven patients, GSWs in 44, and SWs in 2 5 . Forty-two patients with other penetrating mechanisms did not sustain aerodiges­ tive injury. Forty of the 76 patients with aerodigestive injury required an emergency airway in the ED, one of whom had sus­ tained blunt trauma. Orotracheal intubation was successful in 28 patients. In nine patients orotracheal intubation failed, and a cricothyrotomy was performed. Flexible endoscopic intubation was performed in three patients. Of the 38 patients with laryn­ gotracheal trauma, 20 required an emergency airway in the ED. Flexible endoscopic nasotracheal intubation was performed in one patient. Of the remaining patients, RSI failed in five and a cricothyrotomy was performed. The failure rate for RSI was 23% in the GSW group and 20% in the SW group. Twenty­ five of 49 patients with isolated pharyngoesophageal injuries required an emergency airway, 1 6 due to airway compromise secondary to pharyngeal hematoma, and nine due to shock. RSI was successful in 1 7 of these 25 patients. A flexible endoscopic intubation was performed in three patients and a cricothy­ rotomy in five. The authors concluded that RSI is the easiest technique in most cases of aerodigestive injury. However, in the presence of large hematomas, RSI can be difficult and poten­ tially dangerous. 15 If an RSI is undertaken, an experienced prac­ titioner should be ready to perform a surgical airway, should the orotracheal intubation fail. In 22.5% of attempted RSI in

Ai rway M a nagement in Pe netrat i n g Neck I nj u ry

this study, the airway was lost and a cricothyrotomy was neces­ sary, highlighting the importance of the concept of a "double setup" (preparation for immediate surgical airway in the event of intubation failure) . The authors suggest that flexible endo­ scopic nasotracheal intubation is the safest approach provided that the patient has adequate cardiovascular stability. 15 Bumpous et al. 35 performed a retrospective review of 16 patients with penetrating injury to the visceral compartment of the neck who were treated in a level I trauma center over an 8-year period. There were nine handgun injuries, one shotgun injury, five SWs, one razor slash, and two victims of penetrating trauma associated with a motor vehicle accident. Three patients sustained zone I injury, 1 1 zone II injury, and two patients, zone III injury. Eleven patients sustained tracheal injury, six esophageal injury, and five laryngeal injury. Multiple sites of aerodigestive tract injury occurred in 1 3 patients. Tracheotomy was required in 1 2 of the 1 6 patients. Gussack et al. 84 reported a series of 1 1 7 patients with PNI of whom eight had penetrating laryngotracheal injury. Of these eight patients with penetrating laryngotracheal injury, six under­ went orotracheal intubation and two were intubated through the wound.84 Four of those who underwent orotracheal intubation subsequently required tracheotomy. Both patients intubated through the wound required tracheotomy. No "untoward effect" occurred related to the orotracheal intubation.84 The authors also reviewed an additional 392 cases of laryngotracheal trauma from 1 2 published series which included 1 2 3 cases of penetrat­ ing trauma. An astonishing 73% of the 392 cases required a tracheotomy. Gussack et al. 84 also reported a series of 1 2 patients with penetrating trauma to the laryngotracheal complex. The mechanism of injury was GSW in five patients and SW in seven. Nine of the patients with penetrating laryngotracheal injury required active airway control and were orally intubated. Three required an emergency tracheotomy, two with SWs and one patient with a GSW No intubation failures were reported. The authors felt that intubation is the primary method of airway control, and is generally more expeditious than tracheotomy in the majority of patients. However, they went on to state that the practitioner should move quickly to tracheotomy if intubation is difficult.84 Cricothyrotomy was said to be relatively contrain­ dicated if laryngeal trauma is suspected. 84 In a series of 1 63 PNis reported by Soliman et al.,5 1 08 were intubated either in the ED trauma bay or in the field, 8 underwent emergency cricothyrotomy, and two emergency tracheotomy. Sixty patients were resuscitated in the ED and treated nonoperatively. Of these, 36 patients were orally intu­ bated and two underwent cricothyrotomy. Details of intubation technique were not provided.5 Kummer et a!. 85 identified 1 04 traumatic airway injuries (pharynx, larynx, trachea, main bronchi) in a series of 1 2 , 1 87 trauma patients treated at Sunnybrook Health Sciences Centre in Toronto. The pharynx, larynx, and cervical trachea were con­ sidered to be the upper airway. Sixty-eight patients were victims of penetrating trauma, of whom 62 had upper airway inj ury. A definitive airway was secured at the scene or en route in 32 patients and at a referring hospital in 22. Seventeen patients had their airway secured in the trauma room during initial assessment and resuscitation ( 1 0 oro tracheal intubations,

stx flexible bronchoscopic intubations, and one through the wound) and 30 in the OR as part of treatment for the air­ way inj ury or because surgery was necessary for other inj uries. Airway intervention in the OR included 1 5 oral intubations, one nasal intubation, five flexible bronchoscpoic intubations, six surgical airways, and three through the wound. Intubation difficulty was recorded in 1 5 patients. However, more complex interventions than simple intubation under direct laryngos­ copy was required in 30 patients. Pre-hospital definitive air­ way management had a significantly higher mortality ( 1 9 of 32 patients) . Forty-three of the victims of penetrating trauma (63%) required tracheotomy as part of their traumatic airway injury management.85 There is no uniform agreement on the airway management method of choice in PNf and there is a paucity of evidence to support a best practice approach.65·85 Controversy per­ sists and management varies from institution to institution.3 The method chosen must depend on the practitioner's exper­ tise with the various approaches,3 and in general, the technique with which the practitioner is most comfortable is utilized?6 However, familiarity with multiple approaches to secure the airway is required as success with any single technique is not guaranteed,76 and backup plans must be in place should the primary technique fail. 2 9 Orotracheal intubation is the most common method of air­ way management in PNI 17 and in most cases, is the easiest and most appropriate technique. 1 •3 However, in general, oro tracheal intubation in the ED should only be performed in patients with severe respiratory distress or imminent cardiac arrest and with preparations in place to perform a surgical airway if needed.17 The use of muscle relaxants is controversial. 1 7 Rapid sequence intubation (RSI) can b e considered when the airway is threatened but the anatomic structural relation­ ships are well preserved,6 and is more suitable in uncoopera­ tive and hemodynamically unstable patients. 65 The use of RSI in PNI was reported by Shearer et al.43 with a success rate of 98% and by Mandavia et al.8 2 with a success rate of 1 00%. However, the results of these studies may not apply to patients with primary airway injury. Kummer et al. 85 reported 59 oral and 1 2 nasal intubations in a series of 1 04 patients with trau­ matic airway injury. Difficulties in intubation were recorded in 1 5 patients. Bell et al.9 reported two failed and 48 successful oral intu­ bations in PNI. However, Eggen and Jorden38 reported 8/26 "initially unsuccessful" intubations in PNI, four of which were failed oral intubations. Gussack et al.77'84 reported successful orotracheal intubation in penetrating laryngotracheal injury. However, Vassiliu et al. 1 5 reported a failure rate of 22.5% with RSI in penetrating aerodigestive injury. Endotracheal intubation must be approached with great caution in the presence of PNI.54 If a penetrating injury exists distal to the larynx, creation of a false passage can occur with airway disruption and obstruction.54 Although the bougie has been used in PNI, it is a blind technique, has similar risks,6 and has been said to be contraindicated if there is any possibil­ ity of distal airway injury. 54 Video-laryngoscopy (VL) may pro­ vide an improved laryngoscopic view, however its use in PNI has not been described, and it is not obvious that it would

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overcome the difficulties associated with blood in the airway and anatomic distortion. 6 A prospective randomized controlled trial compared direct laryngoscopy and GlideScope video­ laryngoscopy (GVL) for emergency intubation in 623 trauma patients.86 There was no difference between the groups in first­ pass success or survival. Median intubation times were longer in the GVL group. In a subgroup with severe head inj ury, there was a higher incidence of oxygen saturation � 80o/o and a higher mortality rate in the GVL group.86 VL can be combined with fiberoptic bronchoscopy.65 In this combined technique, the VL can help guide the flexible bronchoscope by visualizing the larynx and the tip of the bronchoscope. 65 Endotracheal tube (ETT) passage through the glottis over the bronchoscope can be visualized by the VL. The flexible bronchoscope can also be used to perform the intubation as part of an RSI technique.7 This technique may be useful in combative patients who oth­ erwise do not have predictors of difficult intubation to evaluate the airway for the presence of injury or blood below the vocal cords? RSI can be difficult and potentially dangerous in the presence of PNI and should only be undertaken if judged likely to be successful and the personnel and equipment necessary to establish a surgical airway must be immediately available should the intubation fail (a "double setup"). The risks and benefits of RSI versus an awake intubation must be considered. 87 PNI is the most common indication for awake intubation in trauma.87 Awake flexible bronchoscopic intubation has been advocated as the safest method for most patients with PNI and should be considered in all cooperative patients with suspected airway injury.7·88 It has been considered to be the gold standard for safely securing the airway in patients with traumatic airway injury.54 It may also be the safest approach in patients with large neck hematomas who are not in respiratory distress.17 However, this technique may only be feasible in stable, cooperative patients who are not in severe respiratory distress, and is usually not pos­ sible in combative patients or when immediate airway control is required.6·7·14 Flexible bronchoscopic intubation is considered to be contraindicated in the presence of severe respiratory distress or apnea. 17 Blood in the airway may also impair bronchoscopic visu­ alization.6 The nasal route may require less patient cooperation. Remifentanil, dexmedetomidine, or ketamine may be useful in facilitating awake intubation in the presence of airway trauma,81'88 but must be used with extreme caution if at all in the presence of airway obstruction. The flexible bronchoscopic technique has the advantage that airway injuries can be identified and the ETT passed distal to the injury. In the moribund or apneic patient, or in the presence of massive upper airway bleeding, awake orotra­ cheal intubation may be the most expeditious approach? If an airway must be immediately established and endotra­ cheal intubation fails, then cricothyrotomy is indicated, 15· 29·79·80 but may be difficult in the presence of large midline hemato­ mas.17 Cricothyrotomy in the ED may be required in about 6o/o of PNis and 1 2o/o of laryngotracheal injuries. 1 7 Conversion to tracheotomy can be performed as soon as the clinical situation permits/9 or within 24 hours, 87 although the necessity of routine conversion to tracheotomy is controversial. 89 Cricothyrotomy has also been considered to be contraindicated if the exact location of the airway injury is unknown7 and tracheotomy has been advocated in this setting? Both cricothyrotomy and

tracheotomy can be safely performed in awake patients under local anesthesia.54 In the presence of laryngotracheal injury, if uncertainty exists about the difficulty or safety of intubation, an awake tracheotomy under local anesthesia can be performed under controlled conditions if the patient's condition permits3•79·80 and awake tracheotomy has been recommended for all but minor laryngotracheal injuries.5·81 However, an awake trache­ otomy requires patient cooperation and the difficulties associ­ ated with the performance of a surgical airway in the presence of anatomic distortion in a restless, hypoxemic patient cannot be overemphasized. 14 In extreme circumstances in which a sur­ gical airway is immediately required, most practitioners would consider a cricothyrotomy to be the procedure of choice,38 ,49 and emergency tracheotomy is not considered an appropriate method to establish an emergency definitive airway.34 Blind nasal intubation has been reported in the manage­ ment of PNI with a success rate of 90%.90 However, most authors agree that blind intubation techniques should not be used in PNI because of the risk of producing further injury and complete airway obstruction.7·54 In the presence of a large open laryngotracheal wound, the ETT can be inserted under direct vision into the distal seg­ ment of the exposed airway through the wound.6·17·36·91 The distal larynx or trachea should be grasped with tissue forceps before insertion of the tube to avoid its retraction into the mediastinum. 2,44 The decision to perform an RSI, an awake bronchoscopic intubation, or a primary surgical airway depends on the patient's condition, the clinical setting, the type and severity of airway and systemic injury, and the available personnel, equipment, and expertise.65 • How Was the Patient's Airway Managed?

The patient developed increasing respiratory distress follow­ ing arrival in the ED. A surgeon, an anesthesiologist, and an emergency physician were at the bedside. Options for airway management were discussed. No flexible bronchoscope was immediately available. The degree of respiratory distress rap­ idly increased and awake tracheotomy was not considered to be feasible. A RSI was initiated. The necessary equipment was opened and the surgeon was ready to perform a surgical airway should intubation fail. On direct laryngoscopy a Grade 2 Cormack-Lehane laryn­ goscopic view was obtained with a #4 Macintosh blade and an 8. 0-mm internal diameter (ID) ETT was successfully passed into the trachea on the first attempt. Edema of the pharynx and larynx was noted. ETT position was confirmed by colorimetric carbon dioxide analysis.

OTH E R CO N S I D E RATIONS • What I nvestigations Are Appropriate

in the Sta ble Patient with PNI?

Structured physical examination can b e used t o triage patients with PNI regardless of the zone of injury.4 Patients can be cat­ egorized into those with "hard signs," "soft signs," or "no signs" of vascular or aerodigestive injury. 2

Ai rway M a nagement i n Pe netrat i n g Neck I nj u ry

Those with "hard signs" require immediate resuscitation and surgical exploration without delay for definitive investiga­ tions. 17 If time permits, chest and neck radiographs may be helpful in locating foreign bodies and ruling out pneumotho­ rax. 17 Spinal fractures, retropharyngeal hematoma, pneumo­ mediastinum, widened mediastinum, and SC emphysema may also be evident. 14·17·36 Approximately 1 4% of SWs and 1 6% of GSWs to the neck are associated with a heme/pneumothorax. 17 For unstable patients taken to the OR, panendoscopy (laryn­ goscopy, pharyngoscopy, bronchoscopy, and esophagoscopy) is usually performed at the same time.5 Patients with "soft signs" of vascular or aerodigestive injury require investigation. Investigation protocols are evolving with the introduction of new technology and currently are not uni­ form. In particular, the replacement of the linear array of detec­ tors in computed tomography by a rwo-dimensional detector array that acquires multiple slices simultaneously within 2 to 3 minutes and provides high-quality three-dimensional images has revolutionized the evaluation of PNI. 5 The vascular images are referred to as computed tomographic angiography (CTA) .5 MDCTA not only images the vasculature and the aerodigestive tracts with a single examination, but the surrounding soft tissues and bony cervical spine are also evaluated with high-resolution, multiplanar, three-dimensional, operator-independent images using a contrast load that is administered peripherally. 2 The path of the missile can be inferred by the tracked air.5 Digital subtraction 4 vessel catheter angiography has been considered to be the gold standard for detection of vascular injuries, has well-documented efficacy,9·36'5 2 ·9 2-95 and remained standard practice for many years.17 With the surgical exposure challenges associated with zone I and III injury, imaging was obtained whenever possible, 2 and routine angiography has been suggested regardless of clinical findings.96 However, in one study only 5% of 1 48 zone I and 1 3% of zone III injuries required treatment for vascular injury. 53 In a review of 1 1 0 patients with zone II PNI, 45 underwent arteriography based on proxim­ ity or soft signs of vascular injury but only 1 had an arterial injury requiring surgery that was not predicted by physical findings.97 A second study of PNI involving all zones, reported one vascular injury requiring surgery in 63 arteriograms.98 No significant arterial injuries were identified that did not have suggestive physical findings.98 The authors concluded that the angiogram result did not alter management in zone II penetrat­ ing neck injuries.98 In a study of 223 patients with PNI, 1 76 underwent angiography. 10 Abnormalities were detected in 34 patients, of whom 1 4 required treatment of the vascular lesion. 1 0 Angiography i s invasive and has a n associated complication rate of 0. 1 6% to 2.0%.36'98 Helical CTA (HCTA) has been compared to conventional angiography for the diagnosis of arterial inj uries of the neck in several studies, and a sensitivity and specificity for HCTA as high as 90% to 1 00% has been reported.9·99-102 Mazolewski et al. , 1 0 1 i n a prospective study o f zone II PNI, determined the sensitivity, specificity, PPV, and NPV of CT angiography for significant injury to be 1 00%, 9 1 %, 75%, and 1 00% respec­ tively. In 2002, Munera et al. 103 reported a sensitivity of 1 00% and specificity of 9 8 . 6% in the evaluation of arterial injury in PNI. Inaba et al. 104 in a prospective study of PNI reported that

MDCTA achieved 1 00% sensitivity and 9 3 . 5 % specificity in detecting all vascular and aerodigestive injuries. In 20 1 2 lnaba et al. 2 reported a prospective multicenter study of 453 PNis in which patients with hard signs of vascular or aerodigestive injury underwent immediate surgical exploration, and those with no signs were observed for a minimum of 24 hours with no missed injuries. The 225 patients with soft signs underwent MDCTA. Twenty-rwo vascular inj uries were diagnosed, five confirmed at angiography and 1 7 at surgery. Two patients had a false positive MDCTA; one inj ury was ruled out at surgery and one at angiography. MDCTA was nondiagnostic in four patients because of retained missile artifact and three of these patients underwent angiography. The specificity of MDCTA was 97. 5% and the sensitivity, 1 00%. Thirty-nine of the 225 patients who underwent MDCTA were investigated for prox­ imity alone and actually did not have one of the preestablished soft signs. All of the MDCTAs that were done because ofprox­ imity alone were negative. 2 In 20 1 6 Madsen et al. 1 1 reported a retrospective review of 5 1 0 PNis in a trauma registry. Twenty­ eight unstable patients underwent emergency surgery without prior imaging. CTA was used as the first line of imaging to exclude a vascular inj ury and catheter-directed angiography was reserved for equivocal findings, or where artifacts com­ promised interpretation of the CTA, or for therapeutic intent. Three hundred and eighty-seven patients underwent CTA of whom a vascular inj ury was diagnosed in 70. Sixteen pro­ ceeded to angiography and a vascular inj ury was confirmed in eight. One additional patient underwent negative exploration. Therefore 9 of 70 CTAs were falsely positive ( 1 3%) . Three patients who had a normal CT on admission returned with a pseudo-aneurysm (0.95% false negative) . 1 1 Metallic foreign bodies can lead to suboptimal or nondiagnostic imaging in 1 % to 1 . 8% o f examinations. 2,44 A 20 1 5 review considered CTA to be the diagnostic modality of choice and the standard of care for evaluation of possible penetrating inj ury to the cervi­ cal arteries. 5 2 Color flow Doppler imaging and duplex ultrasonography have also been used in the evaluation of PNJ.3·14·76 The color flow Doppler has the disadvantage of being operator depen­ dent. 17 1he specificity of duplex ultrasound has been quoted at 85% to 1 00% and the sensitivity at 9 1 % to 1 00%.30 As noted above, for unstable patients with PNI, panen­ doscopy is usually performed at the time of emergency sur­ gery.5 The optimal diagnostic strategy for PNI patients with soft signs of aerodigestive tract injury is controversial.5 Flexible endoscopy has been said to be the investigation of choice for suspected laryngotracheal trauma14 and is indicated in the pres­ ence of proximity injury with soft signs or CT findings of a missile tract near the larynx or trachea. 17 Direct laryngoscopy may also be used in the evaluation of laryngeal trauma.80·105 Triple endoscopy (laryngoscopy, bronchoscopy, and esophagos­ copy) has been recommended as mandatory for all stable PNI patients suspected of having upper airway injury. 1 7 Flexible bronchoscopy can be performed in the emergency room under topical anesthesia if the patient is cooperative.17'81'91 The most common findings are blood or edema in the laryngotracheal tract and vocal cord dyskinesia.17 Rigid bronchoscopy has been said to be more definitive for diagnosing the exact site and size

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of airway trauma but requires special skills, general anesthesia, and neck extension.91 The diagnostic imaging procedure of choice in the evalua­ tion of suspected laryngeal injury is high-resolution CT scan­ ning, which provides the most complete radiologic assessment of the larynx.80·106 Computed tomography can help differ­ entiate patients who require surgery from those who can be observed.89 In the study by Inaba et al. , of 225 patients with PNI who underwent MDCTA, aerodigestive tract injury was diagnosed in six; three esophageal and three tracheal. All three tracheal injuries were repaired in the OR. 2 Three patients had air tracking that was suspicious for aerodigestive inj ury but ruled out on endoscopic examination and contrast swallow. In 1 94 MDCTAs that were negative for vascular or aerodigestive injuries, there were no missed injuries on follow-up. The sen­ sitivity and specificity of MDCTA for vascular or aerodigestive injury was 1 00% and 97. 5%. However, it has been said that CT scanning cannot be recommended as a replacement for triple endoscopy in PNI106 and controversy exists with regard to the utility of CT scanning in the evaluation of laryngeal injury?9 As its resolution increases, MDCTA is replacing laryn­ goscopy and tracheobronchoscopy as the diagnostic modality of choice in patients with subtle inj uries of the airway. 5 2 There are no hard signs of pharyngoesophageal injury. 1 7 Soft signs require evaluation of the pharynx and esophagus, although only 1 8% of patients with soft signs have pharyngoesophageal trauma. 17 Diagnostic modalities include CTA, esophagoscopy, and contrast swallow studies. 17 Contrast esophagography is the most commonly used study for investigation of the esopha­ gus,17 followed by esophagoscopy if needed.5 2 Esophagography has been used in 82% of suspected esophageal injuries, and esophagoscopy in 1 8%? Water-soluble gastrograffin has been considered the initial contrast agent of choice1 1'5 2 and has a reported 57% to 80% accuracy in diagnosis of esophageal injury,5 2 although the choice of contrast material is controver­ sial.5 If no leak is identified, the study can be repeated with thin barium which is more sensitive in the diagnosis of smaller injuries.5·17 Thin barium is used as the initial contrast in some centers. 5 2 The sensitivity of CT imaging after swallowed intra­ venous contrast has been shown to be equivalent to barium swallow.89 Esophagography has been reported to have a sensi­ tivity of 50% to 90%.3 If esophagography is normal, flexible endoscopy can be performed. 5 2 Esophagoscopy can also be per­ formed when esophagography cannot be performed. 1 1 Flexible endoscopy alone has a reported accuracy of 97% to 99.3% in detecting esophageal perforations, and when combined with esophagography the accuracy approaches 1 00%.5 2 Controversy surrounds the choice of flexible versus rigid esophagoscopy.5 Insuffiation of air through the flexible scope can worsen SC emphysema and produce pneumomediastinum if a tear is pres­ ent.5 Rigid esophagoscopy by itself has been reported to have a sensitivity of 1 00%,5 may be superior to flexible endoscopy in evaluation of the upper esophagus, and is the investigation of choice after esophagography for some authors . 1 7 1he most com­ monly used algorithms for suspected aerodigestive tract inju­ ries in patients who do not meet criteria for neck exploration include esophagography and endoscopy,5 but this strategy is

labor and resource intensive, and endoscopy itself carries a risk of iatrogenic aerodigestive injury.5 ,44 MDCTA has been used as a screening test for aerodigestive inj ury prior to endoscopy,5 although data on the accuracy of CT-esophagograms in the evaluation of penetrating injury to the esophagus is limited. 5 2 Soliman et al.5 have proposed that patients with symptoms suggestive of aerodigestive injury undergo MDCTA. If the MDCTA is suspicious, then esophagography and/or esopha­ goscopy should be performed, whereas if the MDCTA is nega­ tive the patients can be observed.5 It is likely that MDCTA will play an ever-increasing role in the diagnosis of penetrating aerodigestive injury, and that the role of endoscopy will become more limited.5 In the study performed by Inaba et al} patients with soft signs of aerodigestive injury underwent MDCTA. Three esophageal injuries were identified. One was repaired in the OR and the remaining two were investigated with esopha­ gography. One small esophageal leak was managed conserva­ tively. The second contrast esophagogram did not identifY a leak, however a repeat CT 4 days later demonstrated a reno­ pharyngeal abscess and repeat esophagogram identified a leak which was managed surgically. There were no missed injuries in the presence of a negative MDCTA. 2 As previously noted, the sensitivity and specificity of MDCTA in detecting clinically significant vascular or aerodigestive injury after PNI has been reported to be 1 00% and 97.5%. 2 In a 20 1 3 review, Shiroff et al.44 concluded that comprehensive physical examination combined with MDCTA can effectively identifY or exclude vascular and aerodigestive inj ury after PNI. X-rays of the cervical spine and chest revealed surgical emphysema in the neck, a left upper lung field opacity compat­ ible with contusion or hemothorax, and a bullet fragment over the left scapula. Following intubation and placement of a left chest tube, the patient was taken to the CT scanner sedated and paralyzed with neuromuscular blocking agents. An enhanced CT scan revealed no vascular injury in the neck. Extensive surgical emphysema was present but no airway injury was identified. • What Is The Appropriate Disposition

of the Patient with PN I?

Unstable patients with hard signs o f vascular or aerodigestive injury are taken to the OR for immediate surgical explora­ tion. Stable patients without airway compromise who have soft signs undergo evaluation as directed by the physical examina­ tion. MDCTA is a highly sensitive and specific initial screen­ ing modality and when combined with comprehensive physical examination can effectively identifY or exclude vascular or aerodigestive injury.44 If a significant injury is identified, fur­ ther investigation and surgical management is undertaken as indicated. If no injury is identified, or no signs or symptoms of significant injury are present, then observation is appropriate. 2 The patient was taken to the OR for neck exploration. In the OR, a rigid pharyngolaryngoscopy, flexible bronchoscopy, and flexible esophagoscopy were performed. No penetrating injury was identified although the cephalad trachea could not be examined due to the presence of the ETT. Edema of the pharynx

Ai rway M a nagement i n Pe netrat i n g Neck I nj u ry

and larynx was again noted. On neck exploration penetrating injury to the trachea at the third and fourth tracheal rings was identified and repaired, and a tracheotomy was performed. The projectile tract was followed to the level of the cervical spine. Soft tissue disruption was noted in the tracheoesophageal groove and raised the likelihood of recurrent laryngeal nerve injury. Nasopharyngoscopy was performed on postoperative day 2 and confirmed vocal cord palsy. The patient was decannulated on postoperative day 3 . O n follow-up exam 1 month postoperatively, the patient had no shortness of breath but was still hoarse. Endoscopy revealed a persistently paralyzed vocal cord and minimal narrowing at the site of the tracheal injury.

S U M MARY Optimal management of PNI requires knowledge of the anat­ omy of the neck, an understanding of the mechanism of injury, careful clinical examination, and investigation as directed by the physical exam. Management of the traumatized airway can prove to be the ultimate test of a practitioner's technical skills34 and clinical judgment.

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Ai rway M a n a g e m e n t in the Operati n g Room 49. De Ia Cruz A, Chandler JR. Management of penetrating wounds of the neck. Surg Gynecol Obstet. 1 973; 1 37(3):45 8-460. 50. Dunbar LL, Adkins RB, Waterhouse G. Penetrating injuries to the neck. Selective management. Am Surg. 1 9 84;50(4) : 1 98-204. 5 1 . Lee C, May M, Sapote P, Amnuay C, Tucker HM, Ogura JH. Penetrating wounds of the neck: selective exploration. A study of I 00 cases. Transactions-Am Acad Ophthalmol Otolaryngol. 1 9 7 1 ;75 (3) :496-509. 52. Feliciano DV Penetrating cervical trauma. "Current Concepts in Penetrating Trauma'', IATSIC Symposium, International Surgical Society, Helsinki, Finland, August 25-29, 20 1 3 . World] Surg. 201 5;39(6) : 1 363- 1 372. 53. Demetriades D, Charalambides D, Lakhoo M. Physical examination and selective conservative management in patients with penetrating injuries of the neck. Br] Surg. 1 993;80 ( 1 2) : 1 534- 1 536. 54. Mercer SJ, Lewis SE, Wilson SJ, Groom P, Mahoney PF. Creating airway management guidelines for casualties with penetrating airway inj uries. J R Army Med Corps. 20 1 0 ; 1 56(4 suppl 1 ) : 3 5 5-360. 55. Farjo LA, Miclau T. Ballistics and mechanisms of tissue wounding. Injury. 1 997;28 (suppl 3):S-C I 2 . 56. Fackler M L . Civilian gunshot wounds and ballistics: dispelling the myths. Emerg Med Clin North Am. 1 998; 1 6 ( 1 ) : 1 7-28. 57. Santucci RA, Chang YJ. Ballistics for physicians: myths about wound ballistics and gunshot inj uries. ] Urol. 2004; 1 7 1 (4) : 1 408- 1 4 1 4 . 5 8 . Fackler ML. Wound ballistics. A review o f common misconceptions. ]AMA. 1 988;25 9 ( 1 8) :2730-2736. 59. Fackler ML. Gunshot wound review. Ann Emerg Med. 1 996;28(2): 1 94-203. 60. Volgas DA, Stannard JP, Alonso JE. Ballistics: a primer for the surgeon. Injury. 2005;36(3) :373-379. 6 1 . Biffi WL, Moore EE, Rehse DH, Offner PJ, Franciose RJ, Burch JM. Selective management of penetrating neck trauma based on cervical level of injury. Am J Surg. 1 997; 1 74 (6) : 678-682. 62. Demetriades D, Theodorou D, Cornwell E Ill, et a!. Penetrating injuries of the neck in patients in stable condition. Physical examination, angiog­ raphy, or color flow Doppler imaging. Arch Surg. 1 995; 1 30(9) : 9 7 1 -975. 63. Hirshberg A, Wall MJ, Johnston RH Jr, Burch JM, Mattox KL. Transcervical gunshot injuries. Am ] Surg. 1 994; 1 67(3) :309-3 1 2 . 64. Sriussadaporn S, Pak-ArtR, Tharavej C, Sirichindakul B, Chiamananthapong S. Selective management of penetrating neck injuries based on clinical pre­ sentations is safe and practical. Int Surg. 200 1 ;86(2):90-93. 65. Jain U, McCunn M, Smith CE, Pittet JF. Management of the trauma­ tized airway. Anesthesiology. 20 1 6; 124( 1 ) : 1 99-206. 66. Atteberry LR, Dennis JW, Menawat SS, Frykberg ER. Physical exami­ nation alone is safe and accurate for evaluation of vascular injuries in penetrating Zone II neck trauma. ] Am Col! Surg. 1 994; 1 79 (6) :657-662. 67. Jarvik JG, Philips GR 3rd, Schwab CW, Schwartz JS, Grossman RI. Penetrating neck trauma: sensitivity of clinical examination and cost­ effectiveness of angiography. Am ] Neuroradiol. 1 995; 1 6 (4): 647-654. 68. Sekharan J, Dennis JW, Veldenz HC, Miranda F, Frykberg ER. Continued experience with physical examination alone for evaluation and manage­ ment of penetrating zone 2 neck injuries: results of 1 4 5 cases. ] Vase Surg. 2000;32(3):483-489. 69. Azuaje RE, Jacobson LE, Glover J, et a!. Reliability of physical examina­ tion as a predictor of vascular injury after penetrating neck trauma. Am Surg. 2003;69 (9) :804-807. 70. Mohammed GS, Pillay WR, Barker P, Robbs JV The role of clinical examination in excluding vascular injury in haemodynamically stable patients with gunshot wounds to the neck. A prospective study of 59 patients. Eur] Vase Endovasc Surg. 2004;2 8 (4):425-430. 7 1 . Pepe PE, Wyatt CH, Bickell WH , Bailey ML, Mattox KL. The relation­ ship between total prehospital time and outcome in hypotensive victims of penetrating injuries. Ann Emerg Med. 1 987; 1 6 (3):293-297. 72. Rhee P, Kuncir EJ, Johnson L, et a!. Cervical spine injury is highly depen­ dent on the mechanism of injury following blunt and penetrating assault. ] Trauma. 2006;6 1 (5 ) : 1 1 66- 1 1 70. 73. Klein Y, Cohn SM, Soffer D, Lynn M, Shaw CM, Hasharoni A. Spine injuries are common among asymptomatic patients after gunshot wounds. J Trauma. 200 5 ; 5 8 (4) :833-836. 74. Medzon R, Rothenhaus T, Bono CM, Grindlinger G, Rathlev NK. Stability of cervical spine fractures after gunshot wounds to the head and neck. Spine. 2005 ;30(20) :2274-2279. 75. Connell RA, Graham CA, Munro PT. Is spinal immobilisation neces­ sary for all patients sustaining isolated penetrating trauma? Injury. 2003;34( 1 2) : 9 1 2-9 1 4 . 7 6 . Rathlev NK, Medzon R , Bracken M E . Evaluation and management o f neck trauma. Emerg Med Clin North Am. 2007;25 (3): 679-694, viii.

77. Gussack GS, Jurkovich GJ. Treatment dilemmas in laryngotracheal trauma. J Trauma. 1 988;28 ( 1 0) : 1 439- 1 444. 78. Corneille MG, Stewart RM, Cohn SM. Upper airway injury and its man­ agement. Semin Thorac Cardiovasc Surg. 2008;20 ( 1 ) : 8 - 1 2 . 7 9 . Butler A P, Wood BP, O'Rourke AK, Porubsky E S . Acute external laryn­ geal trauma: experience with 1 1 2 patients. Ann Otol Rhino! Laryngol. 2005 ; 1 1 4(5) : 3 6 1 -368. 80. O'Mara W, Hebert AF. External laryngeal trauma. J La State Med Soc. 2000; 1 52(5) : 2 1 8-222. 8 1 . Nelson LA. Airway trauma. Int Anesthesia! Clin. 2007;45 (3) :99- 1 1 8. 82. Mandavia DP, Qualls S, Rokos I. Emergency airway management in pen­ etrating neck injury. Ann Emerg Med. 2000;35 (3):22 1 -225. 83. Tallon JM, Ahmed JM, Sealy B. Airway management in penetrating neck trauma at a Canadian tertiary trauma centre. Can J Emerg Med. 2007;9 (2) : 1 0 1 - 1 04. 84. Gussack GS, Jurkovich GJ, Luterman A. Laryngotracheal trauma: a pro­ tocol approach to a rare injury. Laryngoscope. 1 986;96(6): 660-665. 8 5 . Kummer C, Netto FS, Rizoli S, Yee D. A review of traumatic airway inj uries: potential implications for airway assessment and management. Injury. 2007;38 ( 1 ) :27-33. 86. Yeatts OJ, Dutton RP, Hu PF, et a!. Effect of video laryngoscopy on trauma patient survival: a randomized controlled trial. ] Trauma Acute Care Surg. 20 1 3;75 (2) : 2 1 2-2 1 9 . 8 7 . Dupanovic M, Fox H, Kovac A . Management o f the airway in multi trauma. Curr Opin Anaesthesia!. 201 0;23(2):276-282. 88. Abernathy J H Ill, Reeves ST. Airway catastrophes. Curr Opin Anaesthesiol. 20 1 0;23 ( 1 ) : 4 1 -46. 89. Schaefer SO. Management of acute blunt and penetrating external laryn­ geal trauma. Laryngoscope. 20 14; 1 24 ( 1 ) :233-244. 90. Weitzel N, Kendall J, Pons P. Blind nasotracheal intubation for patients with penetrating neck trauma. ] Trauma. 2004;56(5) : 1 097- 1 1 0 1 . 9 1 . Chhabra A, Rudingwa P, Selvam SRP. Pathophysiology and management of airway trauma. Trends Anaesth Crit Care. 20 1 3;3:2 1 6-2 1 9 . 92. Hiatt JR, Busuttil RW, Wilson SE. Impact of routine arteriography on management of penetrating neck injuries. J Vase Surg. 1 984; I (6) : 860-866. 93. McCormick TM, Burch BH. Routine angiographic evaluation of neck and extremity injuries. ] Trauma. 1 979; 1 9 (5 ) :384-387. 94. Reid J D, Weigelt JA, Thai ER, Francis H 3rd. Assessment of proximity of a wound to major vascular structures as an indication for arteriography. Arch Surg. 1 988; 1 23(8) : 942-946. 95. Snyder WH 3rd, Thai ER, Bridges RA, Gerlock AJ, Perry MO, Fry WJ . The validity of normal arteriography in penetrating trauma. Arch Surg. 1 978; 1 1 3 (4):424-426. 96. Rao PM, lvatury RR, Sharma P, Vinzons AT, Nassoura Z, Stahl WM. Cervical vascular injuries: a trauma center experience. Surgery. 1 993; 1 1 4(3): 527-53 1 . 97. Menawat SS, Dennis JW, Laneve LM, Frykberg ER. Are arteriograms necessary in penetrating zone II neck inj uries? ] Vase Surg. 1 992; 1 6(3): 397-400. 98. Rivers SP, Patel Y, Delany HM, Veith FJ. Limited role of arteriography in penetrating neck trauma. J Vase Surg. 1 988;8(2): 1 12-1 16. 99. Gracias VH, Reilly PM, Philpott J, et a!. Computed tomography in the evaluation of penetrating neck trauma: a preliminary study. Arch Surg. 200 1 ; 1 36 ( 1 1 ) : 1 23 1 - 1 23 5 . 1 00. LeBiang SO, Nunez DB, Rivas LA , Falcone S, Pogson S E . Helical com­ puted tomographic angiography in penetrating neck trauma. Emerg Radio!. 1 9 97;4(4) :200-206. 1 0 1 . Mazolewski PJ, Curry JD, Browder T, Fildes J. Computed tomographic scan can be used for surgical decision making in zone II penetrating neck injuries. ] Trauma. 200 1 ; 5 1 (2):3 1 5-3 1 9 . 1 02. Munera F, Soto JA, Palacio D, Velez S M , Medina E. Diagnosis o f arte­ rial injuries caused by penetrating trauma to the neck: comparison of helical CT angiography and conventional angiography. Radiology. 2000;2 1 6 (2):3 56-362. I 03. Munera F, So to JA, Palacio OM, et a!. Penetrating neck inj uries: helical CT angiography for initial evaluation. Radiology. 2002;224 (2) :366-372. I 04. Inaba K, Munera F, McKenney M, et a!. Prospective evaluation of screen­ ing multislice helical computed tomographic angiography in the initial evaluation of penetrating neck injuries. ] Trauma. 2006;6 1 ( 1 ) : 1 44- 149. 105. Goudy SL, Miller FB, Bumpous JM. Neck crepitance: evaluation and management of suspected upper aerodigestive tract inj ury. Laryngoscope. 2002; 1 1 2 (5 ) : 79 1 -79 5 . 1 06. Atkins B Z , Abbate S , Fisher SR, Vaslef S N . Current management o f laryngotracheal trauma: case report and literature review. ] Trauma. 2004;56( 1 ) : 1 8 5- 1 90.

Ai rway M a nagement in Pe netrat i n g Neck I nj u ry

SELF-EVALUATION QU ESTIO N S 37. 1 . Penetrating neck injury classification has divided the neck into three anatomic zones. Zone III extends from A. the level of the clavicles and the sternal notch to the cricoid cartilage

C. hoarseness D. hemoptysis E. stridor 37. 3 . In penetrating neck injury, the investigation of choice for suspected laryngotracheal trauma and vascular injury is

B. the level of the clavicles and the sternal notch to the thyroid cartilage

A. MDCTA

C. the cricoid cartilage to the angle of the mandible

C. flexible bronchoscopic endoscopy

D. the thyroid cartilage to the angle of the mandible

D. duplex ulrrasonography

E. the angle of the mandible to the base of the skull

E. catheter angiography

37.2. The only hard clinical sign diagnostic of laryngotracheal injury in penetrating trauma is A. subcutaneous emphysema B. air escaping from the neck wound

B. direct laryngoscopy

439

440

C H A PT E R 3 8

Airway Manage ment of a Patient in Prone Position Dennis Drapeau and Orlando R. Hung

CAS E PRESENTATION

440

I NTRO DUCTION .

440

AI RWAY CO N S I D E RATIO N S.

440

PREPARATION A N D PLANS FOR TRACH EAL I NTU BATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 1 POST-I NTU BATION A N D VENTI LATION MANAG EM ENT. . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . 446

OTH ER CO N S I D E RATI O N S FOR PAT I E NTS I N . . . . . . . . T H E P RO N E POSITI O N .

446

S U MMARY .

447

SELF-EVALUATIO N Q U ESTI O N S .

449

CASE PRESENTATION A 3 5-year-old intoxicated male 1 79 em tall and weighing 1 1 0 kg (BMI 34 kg·m- 2) presents to the emergency room with a 1 2-inch hunting knife lodged in his upper thoracic spine after an altercation at a cottage party. Initial examination reveals nor­ mal vital signs in the prone position, a reassuring airway, and normal screening neurological exam. Initial x-ray studies con­ firm the knife enters at the level of T3 to T4 and traverses the right side of the spinal canal with the tip of the knife embedded in the T4 vertebral body. The neurosurgeon wishes to take the patient to the operating room for an urgent wound explora­ tion and removal of the foreign body under general anesthesia with careful continuous neurological monitoring throughout the procedure.

I NTRODUCTION • What Are You r Concerns When a Patient Is

Placed in the Prone Position for a Surgical Proced u re?

Proper patient positioning for any medical procedure is an important consideration for a safe and successful outcome. Proper positioning provides for appropriate surgical access and guards against injury due to pressure points and strain on neu­ rological and musculoskeletal structures. The prone position is most commonly required for surgical procedures on the spine, and for selected procedures in neurosurgery, urology, and gen­ eral surgery. This position is complicated by an increased risk of stretch and pressure injury of nerves, cardiovascular instability, difficulty with ventilation, and problems with providing cardio­ pulmonary resuscitation as compared with the supine position. Airway considerations for patients in the prone position may include difficult access to the airway, migration of the endo­ tracheal tube (ETT) , cephalad or caudad with head extension and flexion respectively, 1 changes in ETT cuff pressure, 2 limited ability to reposition the head and neck for bag-mask-ventilation (BMV) , and the potential development of airway edema. This case presents a challenging situation for airway practitio­ ners: securing the airway in an urgent setting in which the patient cannot be easily positioned supine. Limited information is cur­ rently available in the literature to assist the airway practitioner with critical decision making should they encounter rhis situation.

AI RWAY CO N S I D E RATIONS • How Do You Provide Ventilation to a Patient

in the Prone Position if U rgently Needed?

Options to manage the airway in a prone patient are similar to those in the supine patient. BMV should be considered the standard and attempted before other measures because the ease

Ai rway M a n a g e m e n t of a Patient i n Pro n e Pos ition

of BMV will guide all airway management decisions that fol­ low. However, BMV in the prone patient can be difficult due to limited access to the airway, difficult mask seal due to no occipital support to apply counter pressure to the head,3 and lack of clinical experience performing BMV in a prone patient. It may be necessary to use a two-person BMV technique, with one person achieving a mask seal using both hands, while the second person provides manual ventilation. Provided that a good seal can be maintained between the mask and the patient's face, BMV should be reasonably easy in a patient lying prone as gravity tends to move the tongue away from the posterior pha­ ryngeal wall. The authors would recommend quickly moving to a two-person BMV technique (see Chapter 8) and proceeding to alternative methods of ventilation should there be any dif­ ficulty obtaining an adequate mask seal. If BMV is not possible, an extraglottic device (EGO), such as the Laryngeal Mask Airway (LMA) , can be used to pro­ vide emergency ventilation and oxygenation for a patient in the prone position. Several reports have evaluated the ease of insertion of LMA devices in the prone position in manikin studies4·5 as well as for short elective procedures in anesthetized patients.6-16 Despite these reports, there is still considerable debate in the literature regarding the safety of using EGOs for patients in the prone position. 17-22 A number of investigators have reported successful use of EGOs (LMA•, LMA-Supreme•, LMA-ProSeal•, and others) to regain control of the airway and provide positive-pressure ventilation following ETT dislodge­ ment in the prone position. 2 3-26 Insertion of the LMA in the prone patient should be attempted using the classic insertion technique recommended for patients in the supine position. 27 Successful insertion of the LMA may actually be easier in the prone position because gravity helps to move the tongue and epiglottis2 8 away from the posterior pharyngeal wall and mini­ mizes the risk of down-folding of the epiglottis. Other EGOs, such as the Combitube'", may be used while the patient is prone, depending on the skill and experience of the practitioner, as well as the available resources. Currently there are no reports in the literature of the successful use of non-LMA derived EGOs for patients in the prone position. Therefore, the authors do not recommend the use of non-LMA derived devices in elective airway management situations or as first-line rescue devices in emergency situations. • How Do You Manage a Patient with a

Difficult Airway Who Req uires Prone Position ing?

Airway management of the patient with a difficult airway who requires surgery in the prone position poses unique challenges for the anesthesia practitioner. These issues can be categorized according to the etiology of the difficult airway: ( 1 ) anatomical characteristics making ventilation and/ or tracheal intubation difficult and (2) cervical spine instability. If difficult laryngo­ scopic intubation secondary to anatomical characteristics is predicted (LEMON and CRANE, see sections "Difficult DL Intubation: LEMON" and "Difficult VL Intubation: CRANE" in Chapter 1 ) , the technique utilized to manage the airway is dependent on whether or not oxygenation can be readily

provided (by BMV, EGO, or a surgical airway) , aspiration risk, the available resources, as well as the expertise of the practitio­ ner. Once tracheal intubation has been achieved, the ETT must be carefully secured. The situation becomes more challenging when possible cer­ vical spine instability or spinal cord inj ury exists. It is generally believed that awake bronchoscopic intubation and prone posi­ tioning of the patient prior to induction of anesthesia is ideal, because it allows verification of neurological integrity prior to surgery. 29·30 However, there is no high level of evidence to support this practice. In a retrospective review of 1 50 patients with cervical spine injury, Suderman and Crosbf1 found no difference in neurological outcomes following tracheal intuba­ tion awake or under general anesthesia, with or without in­ line cervical spine immobilization (see section "Cervical-Spine (C-Spine) Considerations" in Chapter 1 7) .

PREPARATION A N D PLANS F O R TRAC H EAL I NTU BATION • What Are the Options for Tracheal

Intubation in the Prone Position?

In addition to direct laryngoscopic intubation, alternative intu­ bating techniques can be considered. These include the use of a flexible bronchoscope (FB) , an intubating LMA (LMA­ Fastrach'M, LMA North America Inc., San Diego, CA) , or other EGOs designed to allow intubation through the device, light-guided intubation using the Trachlight'" (Laerdal Medical Corp. , Wappingers Falls, New York, NY) , and digital intuba­ tion. However, there is limited clinical information with regard to the effectiveness and safety of these techniques in patients in the prone position. Baer3 2 performed endotracheal intubation using a direct laryngoscope in the prone position in 200 patients undergo­ ing lumbar surgery. Two failed intubations occurred and these patients were then intubated in the lateral or supine positions, with difficulty.32 This experience emphasizes the importance of airway assessment and management in the supine position when difficulty is predicted. Komasawa et al.33 evaluated the utility of a video-laryngoscope (Pentax-AWS Airway Scope) for tracheal intubation in different positions in a manikin and found the prone position to be feasible for intubation but it took longer and was subjectively more difficult for the practi­ tioner than the supine position. There are several case reports describing airway rescue in prone patients using an FB,34·35 intubating LMA (in a neonate) ,36 and flexible bronchoscopy through an LMA device. 2 6 Induction of anesthesia in patients with posterior thoracic inj uries in the prone position and sub­ sequent successful tracheal intubation with direct laryngos­ copf7 and an intubating LMA38·39 have also been reported. We believe that tracheal intubation of patients in the prone position should be reserved for special and rescue situations and for practitioners with the necessary skills and resources. For elective and non-urgent tracheal intubation of patients requiring prone positioning, it would be prudent to secure the airway in the supine position which is most familiar to the airway practitioner.

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However, intubation in the prone position may be neces­ sary if: 1 . ventilation and oxygenation are ineffective using BMV, the LMA, or other EGOs, 2 . ventilation using BMV, the LMA, or other EGOs is ade­ quate but a definitive airway is desired (e.g., prolonged case, risk of aspiration) , 3 . transfer of the patient to the supine position is impossible, or associated with extreme risk.

• Can I ntubation be Performed in the Latera l

Position?

While transfer of the patient to the supine position would be ideal, it could be difficult to achieve in a timely manner and is not without considerable risk depending on the situation. Therefore, it is desirable to have several alternative approaches for tracheal intubation in this particularly difficult situation. If it is feasible to place the patient in a lateral position, the left lateral decubitus is preferred by some practitioners for laryngoscopy and intubation, as graviry will help to displace the tongue as well as secretions to the left and facilitate visual­ ization of the glottis.3 However, others prefer the right lateral decubitus position as the practitioner's left arm has more room to maneuver during the procedure. The tongue can still be eas­ ily displaced by the laryngoscope in the right lateral decubi­ tus position. Nathanson et al.40 found tracheal intubation of a manikin in the lateral position to be more difficult than in the supine position. The ease of intubation increased with each subsequent attempt, indicating that practitioner experience was a confounding factor.33 ,4° An assistant may be necessary to sta­ bilize the head, neck, and body while performing intubation of a patient in the lateral decubitus position. Blind endotracheal intubation techniques using the intu­ bating LMA (LMA-Fastrach'", LMA North America Inc., San Diego, CA) and the lighted srylet have also been described with a patient in the lateral position.41-43 Practitioner's experience with these intubation techniques will improve the chance of success. However, blind techniques should only be attempted after direct or indirect visualization techniques have failed, espe­ cially in trauma patients with the potential for a full stomach and if there is a possibiliry of anatomic distortion of the airway. • What Are the Options for Positioning This

Patient for Ind uction of General Anesthesia?

This is a complex clinical situation that has to take into consid­ eration each of the following prior to developing an appropriate management plan: 1 . urgency of the situation (e.g. , presence or absence of respira­ tory difficulties and hypoxemia) , 2. risk of regurgitation and aspiration (full stomach secondary to drinking at a parry) , 3. the extent of the patient's spinal inj ury or other associated injuries (following an altercation at a parry) , 4. current hemodynamic status and potential for hemody­ namic changes,

5. the presence of any neurological compromise and degree of concern for impending neurological compromise, 6. the level of the patient's anxiery and willingness to cooperate, 7. the position of the patient at presentation. Ultimately, the anesthesia management plan will weigh the risks and benefits of airway interventions and induction of general anesthesia-keeping the patient in his current position with the risks and benefits of repositioning the patient into a potentially more favorable position. If the risk of neurological compromise is deemed to be high, transferring the patient from supine/sitting to prone or prone to supine would be unacceptable. It would be prudent to manage the anesthesia and airway with the patient at or close to his position at presentation. Regardless of the final plan for positioning the patient, careful consideration must be given to securing the equipment, personnel, and resources required to carry out the management plan. Clear and concise communica­ tion must be provided to all team members regarding the sequence of steps involved in the management plan (Plans A, B, C, and D) . • How Would You Position This Patient for

Ai rway Management if He Presented in the Sitting or U pright Position?

If the patient presenting to the emergency department in the sitting position with stable neurological and hemodynamic status can be transported to the operating room (OR) in sitting posi­ tion with sufficient support and care. There are several options for positioning the patient for anesthetic and airway management: 1 . His airway can be managed awake with topical anesthesia and the patient can then be turned prone before induction of anesthesia. 2. Two OR tables can be placed side-by-side with a sufficient gap to allow the foreign body to rest berween the tables with the patient supine. These OR tables can be adjusted in tandem into an appropriate position (supine, reverse Trendelenburg, semi-sitting, or beach chair) prior to transferring the patient to them (see Figure 38- 1 ) . This method may require a third OR table to be present in the room for transferring the patient to the prone position for the surgical procedure after securing the airway and induction of general anesthesia. The length of the foreign body that remains outside of the thorax is a concern as a particularly lengthy foreign body could get caught on one of the OR tables straddling the foreign body while transferring the patient to the prone position. 3. The patient can be transferred to the supine position on an OR table from the sitting position such that the foreign body will lie above the head of the table. With this approach, support of the patient's shoulders and head will be needed as they will also lie above the head of the OR table. This support of the head and shoulders can be achieved with an extra side table, OR table, stretcher, or other device adjusted to the right height (see Figure 38-2) . 4. Th e patient can b e transported t o the O R i n prone position and then transferred to the OR in the same position. The airway and anesthesia can be managed in the prone position. The risks and benefits of this option will be discussed later in the chapter.

Ai rway M a n a g e m e n t of a Patient i n Pro n e Pos ition

F I G U R E 38- 1 . Two operati n g ta bles ca n be p l aced s i d e-by-side with a sufficient g a p to a l l ow the fore i g n body rest between the ta bles.

F I G U R E 38-2. Using a m a n i k i n with a knife i n the back (a rrow), t h i s fig u re d e m o n strates that the patient with a forei g n body i n the back ca n be tra n sferred to a n operati n g room ta b l e l y i n g supine so that the fore i g n body wi l l l i e a bove the head of the ta b l e a n d the head and s h o u l ders of the patient rest i n g o n a n i n stru ment ta b l e l eveled with the O R table. With t h i s a p proac h , the a i rway ca n be sec u red by a ny tec h n i q u e fa m i l ia r to the a n esthesia p ractitio n e r.

5 . The patient can carefully be placed in the lateral position for airway management before being turned into the prone position for the surgical procedure.

• How Would You Position This Patient for

Airway Management if He Presented in the Prone Position?

For the patient with a dorsal foreign body presenting in the prone position, the options are as follows: 1 . Carry out airway and anesthetic management with the patient in his current position (prone on a stretcher or bed) . Although this option avoids moving or transferring the

patient prior to airway management, the patient would still need to be transferred and positioned on the OR table. The authors do not recommend this option. 2. Transfer the patient to the OR table in their final prone position and manage the airway and induction of general anesthesia in that position. This would allow proper surgi­ cal positioning prior to airway management and ensure the patient was neurologically intact prior to induction of anes­ thesia and the start of the surgical procedure. 3. Arrange OR equipment for anesthetic management in the supine position (see above) and transfer the patient from the prone to supine position for airway management. 4. Turn the patient into the lateral position for airway and anesthetic management (see above) .

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• If the Patient was Cooperative, Could This

Patient's Airway be Managed Awake?

If the patient was cooperative and could be safely positioned to allow for awake airway management, there are no contrain­ dications to manage this patient's airway awake. For a patient presenting in the sitting position, tracheal intubation could be achieved as described in the previous section. During airway topicalization or awake intubation, it is possible that the patient could change his position by coughing or become agitated and combative. Any patient movement could potentially further impale the foreign body into the spine. Excessive body move­ ment can be minimized by a gentle unhurried airway topical­ ization technique and by having assistants support the patient's body position during the procedure. Performing an awake intubation with a patient already in the prone position may be more challenging. Although an OR table could be maneuvered to place the patient in a reverse Trendelenburg/chair position with the patient's head extend­ ing over the end of the OR table, it would be difficult to arrange this position with the appropriate bolsters in place. In addition, any patient discomfort while preparing for or during awake intubation could result in patient movement which could result in the patient falling off the OR table. Lastly, most anesthesia practitioners and assistants are unfa­ miliar with awake intubation in a prone patient and the lack of confidence and preparation may jeopardize the suc­ cess of the technique and the ability to manage any potential complications. • Can Ind uction of Anesthesia in the Prone

Position be Safely Performed in This Patient?

There is considerable debate in the literature about the merits of prone positioning and induction of general anesthesia for elective cases. An increasing number of studies including a sub­ stantial number of patients report induction of anesthesia in the prone position and report the level of complications to be similar to induction of general anesthesia in the supine posi­ tion. However, extrapolation of this limited evidence to clinical scenarios different from the patient populations and procedures in those reported studies should be done with great caution. All of the reported studies which include induction of general anesthesia in the prone position were carried out in elective patients, the majority of whom were not obese, and always stressed the importance of the need to be able to quickly turn the patient supine should any difficulties present themselves during airway management. Therefore using currently available evidence, inducing general anesthesia in the prone position for elective surgical patients does not appear to offer the widest margin of safety. There are several case reports of the induction of general anesthesia and airway management in the prone position for traumatic posterior thoracic inj uries.37-39 Agrawal et al.39 used an inhalation induction followed by tracheal intubation through an ILMA technique for a 25-year-old patient with a normal airway placed in the prone position because of exten­ sive open back wounds. Van Zundert et al. 37 describe successful tracheal intubation using direct laryngoscopy in a non-obese

patient placed in prone position with a pair of scissors lodged in her spine. Another case report of a patient with a normal airway and a traumatic knife inj ury to the lumbar spine was managed with induction of anesthesia and intubation in the prone position using an intubating LMA.38 Assuming that careful consideration is given to select and prepare the method of airway management, this could be a reasonable manage­ ment plan if the risks of positioning the patient in a more conventional position for airway management are deemed unacceptably high.

• How Can Endotracheal I ntubation be

Performed in the Prone Position in the Patient Presented Here?

As stated above (see section "What Are the Options for Tracheal Intubation in the Prone Position?" in this chapter) , successful tracheal intubation has been reported using a variety of techniques. While the practitioner may be unfamiliar with the awkward prone position, tracheal intubation using an FB can be performed in the prone position with the OR table in a reverse Trendelenburg position and an assistant supporting the patient's head (see Figure 38-3) . With an assistant holding the patient's head, tracheal intubation by direct laryngoscopy can also be performed in the prone patient by the airway practitio­ ner who is positioned at the head of the patient facing caudad and who uses the right hand to insert the laryngoscope into the pharynx and expose the glottis (Figure 38-4) . Operating the laryngoscope with the right hand while the practitioner faces the prone patient allows the laryngoscope blade to dis­ place the tongue in the usual manner-away from the right side of the patient's mouth. The practitioner then uses the left hand to insert the ETT into the trachea. This technique of laryngoscopic intubation in prone patients has been shown to be effective (99% success rate) and safe.32 Alternately, direct laryngoscopy and intubation can be performed in a more con­ ventional manner from either side of the patient (Figure 38-5) . An assistant can turn the patient's head to the right and elevate the right shoulder slightly to facilitate access to the mouth. The head and neck can also be placed in the familiar sniffing position. The additional concerns with this technique in the patient requiring spinal precautions would make the former technique (approaching the airway from the head of the bed) more favorable. Agrawal et al. 39 described the successful use of the ILMA for tracheal intubation in a patient in the prone position who presented with inj uries precluding supine positioning. The ILMA can provide a conduit through which an ETT can be advanced into the trachea blindly, or with the aid of a light­ wand, or the FB (see Chapter 1 2) . However, insertion of an intubating LMA (as compared to the LMA-Classic) can be difficult in the prone position. Alternatively, following suc­ cessful placement of the LMA-Classic, an FB can be used to facilitate tracheal intubation through the EGO (see section "Can the Flexible Bronchoscope be Combined with Other Intubation Techniques?" in Chapter 1 0) . Flexible broncho­ scopic guided intubation can be accomplished by passing a

Ai rway M a n a g e m e n t of a Patient i n Pro n e Pos ition

F I G U R E 38-3. Bro n c hoscopic tra c h e a l i ntu batio n i n a m a n i k i n w i t h a knife i n the back (arrow) p l a ced i n the pro n e posit i o n : Orotra c h e a l i ntu batio n u s i n g a flex i b l e bro n c h oscope ca n be performed i n a m a n i k i n p l a ced i n p ro n e position with the operating roo m ta b l e i n a reverse Tre n d e l e n b u rg position a n d an a s s i sta nt su pporti n g the m a n i ki n's head.

F I G U R E 38-4. La ryngosco pic i ntu ba­ tion in a m a n i k i n with a knife in the back (a rrow) p l a ced i n the pro n e position: With the m a n i k i n p l a ced i n pro n e posi­ tion with the o perat i n g room ta b l e i n a reverse Tre n d e le n b u rg position a n d with a n a s s i sta nt h o l d i n g t h e patient's head, d i rect l a ryngoscopic i ntu batio n (the CMAC video-la ryngoscope i s u s e d to s h ow the ETI t h ro u g h the g l otti s open­ i n g) c a n be perfor m ed fro m t h e fro nt of the m a n i k i n with the right hand h o l d i n g the l a ryngosco pe.

F I G U R E 38-5. Laryngoscopic i ntubation of a m a n i ki n p l a ced i n t h e pro n e position: Laryngoscopic i ntu batio n c a n a l so b e per­ formed fro m the side (rig ht) of the m a n i k i n . The i n sert s h ows the l a ryngoscopic view of t h i s tec h n iq ue. The voca l cords (VC) a n d the e p i g l otti s (EG) ca n be v i s u a l ized ea s i l y.

pediatric FB with an ensleeved Aintree Intubation Catheter (AIC, Cook Medical Inc. Bloomington, IN) into the trachea through the "aperture bars" of an in situ LMA-Classic. The bronchoscope and LMA-Classic can then be removed leav­ ing the AIC in the trachea. An ETT ;::o: ?. O-mm ID can be advanced over the AIC into the trachea. Since the patient was cooperative and the risk of aspiration was high, the anesthesia team decided to perform an awake tra­ cheal intubation using an FB (Plan A) with the patient placed prone on the operating room table (see Figure 38-3) . An awake tracheal intubation under direct laryngoscopy in the prone position (see Figure 3 8-4) would be performed should the flexi­ ble bronchoscopic intubation attempt fail (Plan B) . The patient would be placed in the supine position with the foreign body berween rwo OR tables placed side-by-side (see section "How Would You Position This Patient for Airway Management if He Presented in the Sitting or Upright Position?" in this chapter) for airway intervention (Plan C) if both of the techniques were unsuccessful.

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POST-I NTU BATION AND VENTI LATION MANAG E M E NT • How Can the Tracheal Tu be be Secured

Following Intubation in a Patient with a Beard?

To minimize the risk of ETT dislodgement, it is imperative to secure the ETT properly, particularly for patients in a prone position. The most common method of securing the ETT is to tape it to the face. However, in the presence of facial hair, oils on the skin, perspiration, oropharyngeal secretions, and surgical skin preparation solutions, the adhesive tape may not be effec­ tive. Generous use of waterproof tape and the use of multiple attachment points can reinforce the bond to the patient's face. The application of tincture of benzoin to the skin may improve tape adhesiveness. Although adequate taping is required for the prone patient, complete sealing off of the mouth should be avoided, as oropharyngeal secretions should be allowed to drain out. This will minimize pooling of saliva and secretions which may loosen the tape. In addition, the use of an antisi­ alagogue (e.g. , glycopyrrolate) may be helpful as a preventive measure to minimize secretions. Placement of a throat pack in the oropharynx or a gauze bite block may also limit the amount of secretions available to disrupt the bond between the tape and the skin. However, the airway practitioner must always be aware of the potential for local pressure injury (e.g. , lingual nerve injury) associated with the use of throat packs and bite blocks.44,45 Patients with facial hair often pose additional prob­ lems with securing the airway. For these patients, it may be best to tie the ETT around the neck with an umbilical tape. It is important not to tie the ETT too tightly and thereby obstruct venous return from the head. If the ETT cannot be tied around the neck (e.g., procedures around the neck or posterior fossa craniotomy) , other possible options to secure the ETT include: ( 1 ) suturing the ETT to the lips; (2) tying the ETT to the upper incisors (if present) or nares; (3) using a nasotracheal ETT to facilitate securing the ETT with tape; and (4) shaving the patient's beard prior to induction of anesthesia.

OTH E R CO N S I D E RATIONS FOR PATIE NTS I N T H E PRO N E POS ITION • How Can Airway Edema be Minimized in a

Patient in the Prone Position?

Tissue edema, particularly in dependent areas, can occur in sur­ gical procedures involving significant blood loss and/or fluid shifts. The development of post-extubation stridor (PES) or air­ way compromise due to an edematous airway following a sur­ gical procedure in the prone position may require emergency airway interventions. Therefore, all attempts should be made to minimize the development of edema during procedures per­ formed in the prone position. Current fluid management strat­ egies advocate minimizing the amount of intraoperative fluids given during elective surgeries, which is especially prudent in patients requiring surgery in the prone position. Early resusci­ tation with blood components in the setting of hemorrhage is

warranted to minimize the use of crystalloid in order to keep head and neck edema at a minimum. Although the efficacy of this approach has not been scientifically validated, it is our practice to use this approach in order to limit crystalloid use to between 2 to 3 liters in total whenever possible. Venous drainage of the head and neck can be optimized by keeping the head elevated if possible and avoiding compression or "kinking" of j ugular veins. If the head must be turned to one side for airway or surgical access, the degree of rotation should be minimized. • How Can Airway Edema be Assessed and

Managed?

The development of edema in the hypopharynx and larynx while in the prone position can produce airway obstruction following extubation. Clinical signs, such as facial, periorbital or conjunctival edema, distended neck veins, and venous con­ gestion of the head may indicate the presence of upper airway edema. The use of a flexible nasopharyngoscope to assess the extent of airway edema prior to tracheal extubation may be helpful,46 although there have been no studies to confirm its utility. Antonaglia et al.47 evaluated post-extubation laryngeal edema in ICU patients using a rigid laryngoscope by an oto­ laryngologist and were able to successfully identify the amount of edema as well as other lesions which would complicate the post-extubation course (hematoma, granuloma, ulcers, and ary­ tenoid luxation) . There are no scientifically validated methods to assess the degree of postoperative airway edema or to predict post­ extubation airway obstruction (see Chapter 30) . However, the performance of a leak test prior to extubation in patients with suspected airway edema has been suggested. 48 If the patient is being ventilated by a mechanical ventilator, the leak test mea­ sures the decrease in exhaled volume returned to the ventila­ tor following deflation of the ETT cuff. A positive leak test (> 1 1 0 mL or > 1 0% of the tidal volume) has been shown to indicate that airway patency is sufficient to tolerate extubation without PES (99% specificity, 98% PPV) , although a negative leak test is not predictive of the development of PES .49 The leak test can also be performed by deflating the ETT cuff in a spontaneously breathing patient without ventilator support and then occluding the proximal end of the ETT. The patient is observed for signs of an audible leak or coughing around the ETT. The absence of a leak and/or coughing are positive predictors for PES .50 Multiple studies have found the leak test to be either helpful for predicting adverse events51.53 or not,54·56 but they all suffer from study design flaws. A systematic review which included 1 6 studies found odds ratios for the cuff-leak test for predicting laryngeal edema and reintubation were 1 8 and 1 0. 8 , respectively.57 Laryngeal ultrasound is an emerging method for assessing laryngeal anatomy. Lakhal et al.58 showed a strong correlation between laryngeal ultrasound and MRI for measuring tracheal diameter at the cricoid ring in 27 young adults. Ding et al.59 reported a pilot study using a laryngeal ultrasound to predict PES in 4 1 patients. The investigators used real-time ultrasonog­ raphy to evaluate the air leak and to determine the relationship

Ai rway M a n a g e m e n t of a Patient in Pro n e Pos ition

between the air column width difference (ACWD) before and after cuff deflation and the development of PES. The results of this study suggest that laryngeal ultrasonography could be a reliable, noninvasive method in the evaluation of laryngeal morphology and airflow through the upper airway. Two recent reports compared ultrasonographic assessment to cuff-leak test for assessing laryngeal edema.60•61 Surherasan et al.61 determined the US measurement of ACWD could be a useful tool and had similar sensitivity and specificity (70% and 70% respectively) and receiver operating characteristic curve (ROC) compared to the cuff-leak test (0.823 vs. 0. 840, respectively) . Mikaeili et al.60 demonstrated that both the cuff-leak test and ACWD had poor sensitivity (25% and 50%, respectively) , specificity (84% and 54%, respectively) , and positive predictive value (both < 20%) . Therefore, airway practitioners should recognize the potential limitations of the application of both of these tests in clinical practice. Interestingly, Antonaglia et al.47 found the cuff-leak test correlated with the amount of laryngeal edema as assessed by rigid laryngoscope but not the occurrence of PES . This could explain some of the discrepancy in evaluations of the cuff-leak test and ACWD as tests for laryngeal edema as they relied on PES as a surrogate for laryngeal edema. Other predictors of PES including length of intubation, female gender, body mass index, and ratio of ETT size to laryngeal diameter have also been reported.49·62 Kwon et al.63 reported total operative time, and the volume of crystalloid and blood given to be risk factors for delayed extubation. Even though the patient may have passed the tests for laryn­ geal edema assessment, if there is clinical evidence of facial and possible airway edema, it would be prudent to perform extuba­ tion over an 1 1 -Fr ETT exchange catheter (Cook Critical Care, Bloomington, IN) to provide a means for oxygenation should post-extubation airway obstruction occur. For patients failing the leak test, the airway practitioner can perform nasopha­ ryngoscopy, video-laryngoscopy, and/or laryngeal ultrasound to provide additional information to aid in determining the risk for post-extubation problems. If there are still sufficient concerns of airway edema, the authors recommend leaving the ETT in place until the airway edema resolves and a subsequent leak test is satisfactory. Although failing the laryngeal edema tests may not predict post-extubation problems with high spec­ ificity, using this approach provides for the greatest margin of safety for the patient. Appropriate treatment of airway edema includes elevation of the head and the use of steroids and diuretics. The effi­ cacy of these measures has not been scientifically validated. Two meta-analyses64·65 provide a comprehensive review of the effect of steroids on PES and showed that there is evi­ dence to support multiple doses of steroids given 1 2 to 24 hours prior to extubation in adults for preventing PES in high-risk patients (as determined by the cuff-leak test) . The evidence for prophylactic steroids in neonates or children is heterogeneous but shows a trend toward benefit and should be considered for high-risk patients.65 Steroids may reduce the amount of airway edema and decrease the risk of post­ extubation airway obstruction, however, evidence supporting a decreased rate of reintubation only exists in the pediatric population. 66-70

S U M MARY Airway management in a prone patient presents a unique chal­ lenge to all airway practitioners. While the principles of airway management (BMV, use of an EGO, tracheal intubation, and surgical access) remain unchanged for a patient in any posi­ tion, oxygenation using these techniques in a prone patient may be difficult and unfamiliar to most airway practitioners. The choice of an airway intervention technique is dependent on the urgency of the clinical status, the available resources, the patient's position, and the skills of the airway practitioner. All airway practitioners must have a strategy to manage a dif­ ficult or failed airway in a patient in the prone position. Special attention must be paid to intraoperative fluid management and the assessment of airway edema prior to tracheal extubation in prone patients, particularly for patients undergoing long surgi­ cal procedures with significant fluid shifts.

REFERENCES I . Minonishi T, Kinoshita H, Hirayama M, et al. The supine-to-prone position change induces modification of endotracheal tube cuff pressure accompanied by tube displacement. J Clin Anesth. 20 1 3;25 ( 1 ):28-3 1 . 2 . Athiraman U , Gupta R, Singh G . Endotracheal cuff pressure changes with change in position in neurosurgical patients. lnt J Crit llln lnj Sci. 20 1 5;5 (4) :237 -24 1 . 3 . Cupitt JM. Induction o f anaesthesia i n morbidly obese patients. Br J Anaesth. 1 999;83(6) : 964-965. 4. Komasawa N, Ueki R, Fujii A, et al. Comparison of Laryngeal Mask Supreme• and Soft Sea!• for airway management in several positions. J Anesth. 20 1 1 ;2 5 (4) : 535-539. 5 . Gupta B, Gupta S, Hijam B, Shende P, Rewari V Comparison of three supraglottic airway devices for airway rescue in the prone position: a man­ ikin-based study. ] Emerg Trauma Shock. 20 1 5 ; 8 (4) : 1 8 8 - 1 92. 6. Taxak S, Gopinath A, Saini S, Bansal T, Ahlawat MS, Bala M. A prospec­ tive study to evaluate and compare laryngeal mask airway ProSeal and i-gel airway in the prone position. Saudi J Anaesth. 20 1 5 ;9(4):446-450. 7. Kang F, Li J, Chai X, Yu J, Zhang H, Tang C. Comparison of the i-gel laryngeal mask airway with the LMA-supreme for airway management in patients undergoing elective lumbar vertebral surgery. J Neurosurg Anesthesiol. 20 1 5 ;27 ( 1 ) :37-4 1 . 8 . Olsen KS , Petersen JT, Pedersen NA, Rovsing L . Self-positioning followed by induction of anaesthesia and insertion of a laryngeal mask airway ver­ sus endotracheal intubation and subsequent positioning for spinal sur­ gery in the prone position: a randomised clinical trial. Eur J Anaesthesiol. 20 1 4;3 1 (5):25 9-265 . 9. Lopez AM, Valero R , Hurtado P, Gambus P, Pons M, Anglada T. Comparison of the LMA Supreme with the LMA Proseal for airway management in patients anaesthetized in prone position. Br J Anaesth. 2 0 1 1 ; 1 07(2):265-27 1 . I 0 . Taxak S , Gopinath A. Insertion o f the i-gel airway in prone position. Minerva Anestesiol. 20 1 0;76(5) :38 1 . I I . Sharma V, Verghese C , McKenna PJ. Prospective audit o n the use of the LMA-Supreme for airway management of adult patients under­ going elective orthopaedic surgery in prone position. Br J Anaesth. 2 0 1 0; 1 05 (2) :228-232. 12. Lopez AM, Valero R, Brimacombe ] . Insertion and use of the LMA Supreme in the prone position. Anaesthesia. 20 1 0;6 5 (2) : 1 54- 1 57. 13. Senthil Kumar M, Pandey R, Khanna P. Successful use of i-gel airway in prone position surgery. Paediatr Anaesth. 2009; 1 9 (2) : 1 76- 1 77. 14. Yano T, Imaizumi T, Uneda C, Nakayama R. Lower intracuff pressure of laryngeal mask airway in the lateral and prone positions compared with that in the supine position. J Anesth. 2008;22(3) : 3 1 2-3 1 6. 1 5 . Stevens WC, Mehta PD. Use of the Laryngeal Mask Airway in patients positioned prone for short surgical cases in an ambulatory surgery unit in the United States. J Clin Anesth. 2008;20 (6) :487-488. 1 6. Brimacombe JR, Wenzel V, Keller C. The Proseal laryngeal mask airway in prone patients: a retrospective audit of245 patients. Anaesth Intensive Care. 2007;35 (2) :222-225 .

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Ai rway M a n a g e m e n t i n the Operati n g Room 1 7. Patel A, Clark SR, Schiffmiller M, Schoenberg C, Tewfik G. A survey of practice patterns in the use oflaryngeal mask by pediatric anesthesiologists. Paediatr Anaesth. 201 5;25 ( 1 1 ) : 1 1 27- 1 1 3 1 . 1 8 . Whitacre W, Dieckmann L , Austin PN. An update: use o f laryn­ geal mask airway devices in patients in the prone position. MNA }. 20 1 4;82(2) : 1 0 1 - 1 07. 1 9. Staender S . CON: laryngeal masks must not be used for surgery in the prone position. Eur J Anaesthesia!. 2 0 1 4;3 1 (5):256-258. 20. Kranke P. Penny wise, pound foolish? Trade-offs when using the laryngeal mask airway for spine surgery in the prone position. Eur J Anaesthesia!. 20 1 4;3 1 (5):249-252. 2 1 . Hinkelbein J. PRO: laryngeal masks can be used for surgery in the prone position. Eur] Anaesthesia!. 20 1 4 ; 3 1 (5):253-25 5 . 2 2 . Abrishami A , Zilberman P, Chung F. Brief review: airway rescue with inser­ tion of laryngeal mask airway devices with patients in the prone position. Can ] Anaesth. 20 1 0; 5 7 ( 1 1 ) : 1 0 1 4- 1 020. 23. Dingeman RS, Goumnerova LC, Goobie SM. The use of a laryngeal mask airway for emergent airway management in a prone child. Anesth Analg. 2005; 1 00(3) :670-67 1 . 24. Raphael J, Rosenthal-Canon T, Gozal Y. Emergency airway management with a laryngeal mask airway in a patient placed in the prone position. J Clin Anesth. 2004; 1 6 (7) : 560-5 6 1 . 25. Brimacombe J, Keller C. An unusual case of airway rescue in the prone position with the ProSeal laryngeal mask airway. Can ] Anaesth. 2005;52(8):884. 26. Sohn L, Sawardekar A, Jagannathan N. Airway management options in a prone achondroplastic dwarf with a difficult airway after unintentional tracheal extubation during a wake-up test for spinal fusion: to flip or not to flip? Can ] Anaesth. 20 1 4 ; 6 1 (8) :74 1 -744. 27. Brain A. Proper technique for insertion of the laryngeal mask. Anesthesiology. 1 990;73 (5): 1 053- 1 054. 28. Ng A, Raitt DG, Smith G. Induction of anesthesia and insertion of a laryngeal mask airway in the prone position for minor surgery. Anesth Analg. 2002;94(5) : 1 1 94-1 1 98. 29. Douglass ], Fraser J, Andrzejowski J. Awake intubation and awake prone positioning of a morbidly obese patient for lumbar spine surgery. Anaesthesia. 20 1 4;69(2) : 1 66- 1 69. 30. Malcharek MJ, Rogos B, Watzlawek S, Sorge 0, Sablotzki A, Gille J, Larson CP Jr. Awake fiberoptic intubation and self-positioning in patients at risk of secondary cervical injury: a pilot study. ] Neurosurg Anesthesia!. 20 1 2 ;24(3) : 2 1 7-22 1 . 3 1 . Suderman VS, Crosby ET, Lui A. Elective oral tracheal intubation in cervi­ cal spine-injured adults. Can ] Anaesth. 1 99 1 ;38 (6) :785-789. 32. Baer K. Is it much more difficult to intubate in prone position? Lakartidningen. 1 992;8 9 (44) :3657-3660. 33. Komasawa N, Ueki R, Irani M, Nomura H, Nishi SI, Kaminoh Y. Evaluation of tracheal intubation in several positions by the Pentax-AWS Airway Scope: a manikin study. ] Anesth. 20 1 0;24(6) :908-9 1 2 . 3 4 . Hung MH, Fan S Z , Lin CP, H s u YC, Shih PY, Lee T S . Emergency airway management with fiberoptic intubation in the prone position with a fixed flexed neck. Anesth Analg. 2008; 1 07(5): 1 704- 1 706. 3 5 . Kramer DC, Lo JC, Gilad R, Jenkins A 3rd. Fiberoptic scope as a res­ cue device in an anesthetized patient in the prone position. Anesth Analg. 2007; 1 0 5 (3): 890. 36. Jagannathan N, Jagannathan R. Prone insertion of a size 0 . 5 intubating laryngeal airway overcomes severe upper airway obstruction in an awake neo­ nate with Pierre Robin syndrome. Can ] Anaesth. 2 0 1 2 ; 5 9 ( 1 0) : 1 00 1 - 1 002. 37. van Zundert A, Kuczkowski KM, Tijssen F, Weber E. Direct laryngoscopy and endotracheal intubation in the prone position following traumatic thoracic spine inj ury. ] Anesth. 2008;22 (2) : 1 70- 1 72. 38. Samantaray A. Tracheal intubation in the prone position with an intubat­ ing laryngeal mask airway following posterior spine impaled knife injury. Saudi J Anaesth. 20 1 1 ; 5 (3):329-33 1 . 39. Agrawal S , Sharma JP, Jindal P, Sharma UC, Rajan M . Airway manage­ ment in prone position with an intubating Laryngeal Mask Airway. J Clin Anesth. 2007; 1 9 (4) :293-295. 40. Nathanson MH, Gajraj NM, Newson CD. Tracheal intubation in a manikin: comparison of supine and left lateral positions. Br ] Anaesth. 1 994;73 (5):690-69 1 . 4 1 . Cheng Kl, Chu KS, Chau SW, e t al. Lightwand-assisted intubation of patients in the lateral decubitus position. Anesth Analg. 2004;99 ( 1 ) : 279-283. 42. Dimitriou V, Voyagis GS, latrou C, Brimacombe ] . Flexible lightwand­ guided intubation using the intubating laryngeal mask airway in the supine, right, and left lateral positions in healthy patients by experienced users. Anesth Analg. 2003;96 (3) :896-898.

43. Komatsu R, Nagata 0, Sessler Dl, Ozaki M. The intubating laryngeal mask airway facilitates tracheal intubation in the lateral position. Anesth Analg. 2004;98 (3) : 8 5 8-86 1 . 44. Evers KA, Eindhoven GB, Wierda JM. Transient nerve damage follow­ ing intubation for trans-sphenoidal hypophysectomy. Can ] Anaesth. 1 999;46 ( 1 2) : 1 143- 1 1 4 5 . 45. Wang KC, Chan WS, Tsai CT, Wu GJ, Chang Y, Tseng H C . Lingual nerve injury following the use of an oropharyngeal airway under endotracheal general anesthesia. Acta Anaesthesia! Taiwan. 2006;44 (2) : 1 1 9- 1 22. 46. Bentsianov BL, Parhiscar A, Azer M, Har-E! G. The role of fiberoptic naso­ pharyngoscopy in the management of the acute airway in angioneurotic edema. Laryngoscope. 2000; 1 1 0 ( 1 2) : 2 0 1 6-20 1 9. 47. Antonaglia V, Vergolini A, Pascotto S, et al. Cuff-leak test predicts the severity of postextubation acute laryngeal lesions: a preliminary study. Eur ]Anaesthesia!. 201 0;27(6) : 5 34-54 1 . 48. Miller RL , Cole RP. Association between reduced cuff leak volume and postextubation stridor. Chest. 1 996; 1 1 0 (4) : 1 035- 1 040. 49. Kriner EJ, Shafazand S, Colice GL. The endotracheal tube cuff-leak test as a predictor for postextubation stridor. Respir Care. 2005 ; 5 0 ( 1 2) : 1 632- 1 638. 50. Maury E, Guglielminotti J, Alzieu M, Qureshi T, Guider B, Offenstadt G. How to identify patients with no risk for postextubation stridor? J Crit Care. 2004; 1 9 ( 1 ) :23-28. 5 1 . Chung YH , Chao TY, Chiu CT, Lin MC. The cuff-leak test is a simple tool to verify severe laryngeal edema in patients undergoing long-term mechanical ventilation. Crit Care Medicine. 2006;34 (2) :409-4 1 4 . 52. Suominen P, Taivainen T, Tuominen N, e t al. Optimally fitted tracheal tubes decrease the probability of postextubation adverse events in children undergoing general anesthesia. Paediatr Anaesth. 2006; 1 6 (6) :64 1 -647. 53. Wang CL, Tsai YH , Huang CC, et al. The role of the cuff leak test in predicting the effects of corticosteroid treatment on postextubation stridor. Chang Gung Med]. 2007;30 ( 1 ) : 53-6 1 . 54. Shin SH, Heath K, Reed S , Collins J , Weireter LJ, Britt LD. The cuff leak test is not predictive of successful extubation. Am Surg. 2008;74 ( 1 2) : 1 1 82- 1 1 8 5 . 5 5 . Suominen PK, Tuominen NA, Salminen JT, e t al. The air-leak test i s not a good predictor of postextubation adverse events in children undergoing cardiac surgery. J Cardiothorac Vase Anesth. 2007;2 1 (2) : 1 97-202 . 56. Wratney AT, Benjamin DKJr, Slonim AD, He J, Hamel DS, Cheifetz IM. The endotracheal tube air leak test does not predict extubation outcome in critically ill pediatric patients. Pediatr Crit Care Med. 2008;9(5) :490-496. 57. Zhou T, Zhang HP, Chen WW, et al. Cuff-leak test for predicting postex­ tubation airway complications: a systematic review. ] Evid Based Med. 20 1 1 ;4(4) :242-254. 5 8 . Lakhal K, Delplace X, Cottier JP, et al. The feasibility of ultrasound to assess subglottic diameter. Anesth Analg. 2007; 1 04(3) : 6 1 1 - 6 1 4 . 59. Ding LW, Wang H C , Wu HD, Chang CJ, Yang P C . Laryngeal ultrasound: a useful method in predicting post-extubation stridor. A pilot study. Eur Respir}. 2006;27(2) :384-389. 60. Mikaeili H, Yazdchi M, Tarzamni MK, Ansarin K, Ghasemzadeh M. Laryngeal ultrasonography versus cuff leak test in predicting postextuba­ tion stridor. ] Cardiovasc Thorac Res. 20 1 4;6( 1 ) :25-28. 6 1 . Sutherasan Y, Theerawit P, Hongphanut T, Kiatboonsri C, Kiatboonsri S . Predicting laryngeal edema in intubated patients b y portable intensive care unit ultrasound. ] Crit Care. 2 0 1 3;28(5) :675-680. 62. Erginel S, Ucgun I, Yildirim H, Metintas M, Parspour S . High body mass index and long duration of intubation increase post-extubation stridor in patients with mechanical ventilation. Tohoku J Exp Med. 2005;207(2) : 1 25- 1 32. 63. Kwon B, Yoo JU, Furey CG, Rowbottom J, Emery SE. Risk factors for delayed extubation after single-stage, multi-level anterior cervical decompression and posterior fusion. J Spinal Disord Tech. 2006; 1 9 (6) : 389-393. 64. Jaber S, Jung B, Chanques G, Bonnet F, Marret E. Effects of steroids on reintubation and post-extubation stridor in adults: meta-analysis of ran­ domised controlled trials. Crit Care. 2009; 1 3 (2):R49. 65. Khemani RG, Randolph A, Markovitz B. Corticosteroids for the preven­ tion and treatment of post-extubation stridor in neonates, children and adults. Cochrane Database Syst Rev. 2009 (3) :CDOO ! OOO. 66. Anene 0, Meert KL, Uy H, Simpson P, Sarnaik AP. Dexamethasone for the prevention of postextubation airway obstruction: a prospec­ tive, randomized, double-blind, placebo-controlled trial. Crit Care Med. 1 996;24 ( 1 0) : 1 666- 1 669. 67. Darmon JY, Rauss A, Dreyfuss D, et al. Evaluation of risk factors for laryngeal edema after tracheal extubation in adults and its prevention by dexamethasone. A placebo-controlled, double-blind, multicenter study. Anesthesiology. 1 992;77 (2) :245-25 1 .

Ai rway M a n a g e m e n t of a Patient in Pro n e Pos ition 68. Lukkassen IM, Hassing MB, Markhorst DG. Dexamethasone reduces reintubation rate due to postextubation stridor in a high-risk paediatric population. Acta Paediatr. 2006;95 ( 1 ) : 74-76. 69. Markovitz BP, Randolph AG. Corticosteroids for the prevention of rein­ tubation and postextubation stridor in pediatric patients: a meta-analysis. Pediatr Crit Care Med. 2002;3(3):223-226. 70. Meade MO, Guyatt GH, Cook DJ, Sinuff T, Butler R. Trials of cortico­ steroids to prevent postextubation airway complications. Chest. 200 1 ; 1 20 (6 suppl) :464S-468S.

SELF - EVALUATION QU ESTIONS 3 8 . 1 . Which o f the following i s not acceptable initial method to provide oxygenation and ventilation to an awake cooperative patient lying prone with a knife in the tho­ racic spine in the emergency department? A. Advancing the ETT over a flexible bronchoscope into the trachea B. Establish a surgical airway C. Insertion of a Laryngeal Mask Airway D . Bag-mask-ventilation E. Intubation through an Intubating LMA

38.2. Following orotracheal intubation, which of the following is NOT an acceptable method of securing the endotra­ cheal tube (ETT) in a patient with facial hair? A. Tie the ETT around the neck with an umbilical tape. B. Tie the ETT to the upper incisors. C. Secure the ETT with a waterproof tape after the application of tincture of benzoin to the face. D. Shave the patient's beard under general anesthesia. E. None of the above. 3 8 . 3 . Which of the following is most reliable in assessing postoperative airway edema in a patient who was placed prone for the procedure? A. The amount of intraoperative fluid administered to the patient. B. The presence of facial edema. C. The leak test. D. Flexible nasopharyngoscopy. E. None of the above.

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Lun g Se paration in the Patient with a Difficult Airway Jan R. Morris

CAS E PRESENTATION

450

AN ESTH ESIA CONS I D ERATI ONS . . . . . . . . . . . . . . . . . . . 450 AI RWAY MANAGEM ENT . . . . . .

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POSTO PERATIVE AI RWAY CO N S I D E RATI ONS . . . . . . . . 453 OTH ER CO N S I D ERATIONS . . . . . . . . . . . . . . . . . . . . . . . . 453 S U MMARY . . . . . . . . . . . .

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SELF-EVALUATIO N Q U ESTI O N S .

456

Airway examination reveals a Mallampati II classification, thyromental distance of 5 em, mouth opening of 5 em, man­ dibular mobility of 2 em, normal cervical spine extension, and full dentition.

AN ESTH ESIA CON S I D E RATIONS • Is Th is Patient Fit for Anesthesia?

The patient has spinal cord compression with slowly progressive neurologic symptoms and requires surgery. He has no signifi­ cant comorbidities and needs no additional preoperative medical optimization. • What Anesthetic Technique Is Required?

CASE PRESENTATION A 50-year-old male presents with a 6-month history of pro­ gressive paraparesis. He had sustained a fall at work about 12 months ago and has complained of back pain since that time. He also complains of difficulty with urination and con­ stipation over the past several weeks. Magnetic resonance imag­ ing (MRI) reveals disc herniation at T1 0- 1 1 and spinal cord compression. He has been scheduled for T 1 1 vertebrectomy, spinal cord decompression, and spinal instrumentation via a left thoracotomy. He is otherwise healthy. His medications include acetaminophen, and dexamethasone which has recently been added. On examination, he is 1 73 em (5 ft 8 in) tall and weighs 77 kg ( 1 70 lb) . His vital signs are: BP 1 40/80 mm Hg, HR 69 beats per minute and regular, RR 1 6 breaths per minute, temperature 36.9°C, and oxygen saturation is 99% on room air. Examination of the lower extremities reveals 3/5 motor power in the left leg and 5/5 in the right leg. Sensation is altered below T 1 1 . The chest is clear to auscultation and heart sounds are normal.

General anesthesia is required. Lung separation has been requested by the surgeon to optimize the surgical exposure. • How Can One Lung Ventilation or Lung

Separation be Achieved?

Double lumen tubes (DLTs) have been considered to be the gold standard for lung separation.1·4 However, recently intro­ duced bronchial blockers (BBs) have been shown to provide equivalent surgical exposure when compared to the DLT.5-13 A DLT is preferred over BBs when lung isolation is required to protect the non-diseased lung from contamination with blood or pus, in the presence of a bronchopleural or bronchopleural cutaneous fistula, and to perform unilateral pulmonary lavage. 1 A contralateral DLT is preferred when a sleeve resection, o r lung transplant is performed.5·14 However, there are many clinical situations in which a DLT may not be the best primary choice. 2 The indications for the use of a BB include the difficult airway, the patient already intubated, distorted bronchial anatomy, small adults or young children, the presence of a tracheotomy, when nasal intubation or lobar blockade is required, and to avoid the

Lu ng Sepa ration in the Patient with a Diffi c u l t Ai rway

need for a tube exchange. 1 '3 Currently available BBs include the Univent Torque Control Blocker, the Arndt Wire-Guided Endobronchial Blocker, the Cohen Flexitip Endobronchial Blocker, the Fuji Uniblocker, the HS (Hospital Service) Endoblocker, the Coopdech Endobronchial Blocker,3·5·1 2·15-23 and the EZ-Biocker.9'10' 1 1 '24 One lung ventilation using a DLT is planned. In the operating room (OR) , basic monitors are applied and a left radial arterial catheter is placed under local anesthesia. Following denitrogenation, general anesthesia is induced with propofol 1 75 mg, sufentanil 1 5 flg, and rocuronium 50 mg. Bag-mask-ventilation (BMV) is easily performed. Direct laryn­ goscopy (DL) with a #4 Macintosh blade reveals a Grade 4 Cormack-Lehane view (soft palate only) . Cystic tissue is noted to be present at the posterior aspect of the tongue.

AI RWAY MANAGEMENT • Is Th is a "Difficult Ai rway"?

The term "Difficult Airway" has been used when conventional DL reveals a Cormack-Lehane (CL) Grade 3 (epiglottis only) or Grade 4 (soft palate only) view. 14'2 5-27 Tracheal intubation by DL can certainly be more difficult in the presence of CL 3 or 4 direct laryngoscopic view and this clinical setting may be more appropriately defined as a "difficult intubation." The ASA Task Force on Management of the Difficult Airway defines difficult airway as the clinical situation in which a conventionally trained anesthesiologist experiences difficulry with face-mask ventila­ tion, endotracheal intubation, or both. 2 8 The difficult airway can also be defined as one in which an experienced practitioner anticipates or encounters difficulry with any or all of face-mask ventilation, direct or indirect (e.g. , video) laryngoscopy, tracheal intubation, extraglottic device (EGD) use, or surgical airway. 29 Contextual issues such as anticipated safe apnea time, aspiration risk, presence of obstructing pathology, availabiliry of skilled help and clinical inexperience can also contribute to the degree of difficulry.30 DLTs and the Univent tube have been termed "dif­ ficult tubes" as they can be more difficult to insert due to their increased outside diameter (OD) , shape, lack of a bevel at the tip, and increased overall rigidiry which impedes optimal shaping of the tubes.5·2 5'27 The criteria for difficult DLT insertion have not been well defined. 1 ,2 However, difficulry can be encountered in the presence of a CL II (partial glottis) view14 and it has been shown that placement of a DLT may be challenging in an airway that can be easily intubated with a single lumen tube (SLT) . 2 The Univent is an SLT with an enclosed channel along its con­ cave (anterior) aspect which contains a movable BB.31·32 The OD of the Univent is relatively large as compared to a conventional polyvinyl chloride SLT and it has increased stiffness.3·32 It can be problematic to insert in the setting of a difficult intubation.3 • What Are the Options for Airway

Management in This Patient?

Mask ventilation has been demonstrated to be easy but DL is difficult. The patient's position should have been optimal before induction. If not, then it should be optimized. Head lift and external laryngeal manipulation should be considered part of

best DL technique. A blade change can be considered if it is anticipated that a specific anatomic problem can be overcome. Placement of a DLT is best accomplished with a curved blade as it leaves more space in the pharynx through which to pass the relatively bulky DLT. 14 An Eschmann Tracheal Introducer (ETI, commonly known as "bougie") is unlikely to succeed in the presence of a CL Grade 4 view and may produce trauma. When a patient with a difficult direct laryngoscopy requires lung separation, airway management options include: place­ ment of an SLT and utilization of a BB; placement of a Univent tube; or placement of a DLT. The decision to use an SLT as opposed to a Univent or a DLT is based on the degree of dif­ ficulry anticipated with the more difficult tube, which in turn is a function of the available airway management equipment such as video-laryngoscopes, the airway anatomy/geometry, and the expertise of the airway practitioner. In addition, the anticipated post-operative clinical course must be considered. If postopera­ tive ventilation is possible or probable based on the length and extent or rype of surgery, anticipated fluid shifts and transfusion requirements, hemodynamic stabiliry, or marginal respiratory reserve, placement of a DLT may require a tube changer at the end of the case. 1 ,2'14 Exchange of a DLT for an SLT at the end of the case is not without risk. 2 Edema, secretions, and trauma from the initial intubation1' 2'3'14' 27 may make reintubation at the end of surgery more difficult. Optimal positioning for intuba­ tion at the end of surgery may also be more difficult to achieve. Reintubation at the end of surgery may be extremely difficult and a highly dangerous maneuver3 with potential loss of airway control. 1 Aspiration and airway trauma can also occur. 1 The decision to proceed with intubation with an SLT, a Univent, or a DLT is a matter of clinical judgment, taking into consideration the technical and airway anatomical issues as well as the anticipated clinical course. The requirement for lung sepa­ ration must also be evaluated. The absolute indications for lung separation include massive bleeding or abscess in which the non­ diseased lung must be protected from contamination, unilateral air leak from bronchopleural or bronchopleural cutaneous fistula, or unilateral pulmonary lavage for alveolar proteinosis or cys­ tic fibrosis.U·14'27 Video-assisted thoracoscopic surgery (VATS) has also been included as an absolute indication for lung sepa­ ration. 1 ' 27 Other indications for lung separation are relative and are to improve surgical exposure.3'27 Although many surgical procedures are more easily performed with the lung collapsed, if placement of a DLT or BB is problematic, the need for lung sepa­ ration as well as the safery of the technique must be considered. 14 Intubation techniques that can be used as an alternative to DL include flexible bronchoscopic intubation under general anesthesia, intubation using a video-laryngoscope, or intuba­ tion through an EGD. Intubation of the unconscious patient using the flexible bronchoscope is a widely accepted technique. Jaw thrust and tongue traction can be used to open the pharynx and facilitate passage of the scope. Minimizing the discrepancy between the OD of the bronchoscope and the internal diam­ eter (ID) of the ensleeved endotracheal tube (ETT) will mini­ mize the risk that the tube will meet obstruction as it is passed through the larynx into the trachea over the scope. In the setting of predicted difficult DL, awake flexible bron­ choscopic intubation has historically been considered to be the

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Ai rway M a n a g e m e n t in the Operati n g Room

safest means to secure the airway14 and is still recommended as the preferred technique in the elective setting.3 However, with the introduction of devices that are proving to be useful in the difficult intubation, protocols are changing14 and video­ laryngoscopes are challenging bronchoscopy as the first choice for accessing the difficult airway. 14•33-35 Flexible bronchoscopic intubation using a Univent tube can be more difficult than with a conventional ETT due to the fixed concavity of the Univent as well as its larger OD. 1•36 When performing a flexible bronchoscopic intubation with a DLT, the length of the tube relative to the length of the shaft of the scope limits the maneuverability of the scope. 27•37 The rigidity of the DLT also makes it harder to advance the tube over the scope, though it can be done (see section "Can Awake Flexible Bronchoscopic Intubation be Done with a DLT?" in this chapter) . 27 Intubation with an SLT utilizing a video-laryngoscope, such as the GlideScope•, is widely practiced in the setting of a predicted difficult intubation and is associated with a high degree of success.38·39 In 2005, Hernandez and Wong40 reported the successful placement of a DLT using the GlideScope in a patient with anticipated difficult airway. Bustamante et al.41 subsequently reported the successful placement of DLTs in a dozen patients with anticipated and unanticipated difficult DL using the GlideScope. The authors suggested that the distal aspect of the DLT be pre-curved to about 60 degrees, the stylet be removed when the glottis was engaged, and then the tube rotated 1 80 degrees to cannulate the trachea. In 20 1 2 , Bussieres et al.42 described the use of a customized GlideRite DLT Stylet to facilitate DLT placement using the GlideScope. The device was used successfully in 50 patients without a predicted difficult intubation and in "more than 1 5 patients" with anticipated or proven difficult intubation.42 In 20 1 2 , Hsu et al.43 compared the GlideScope and the Macintosh laryngoscope for DLT insertion in a randomized controlled trial which included 60 patients without difficult intubation predictors. All intubations were performed by rwo anesthesiologists who had previously performed at least 300 tracheal intubations with each device. There was no difference in the first attempt success rate berween the groups and the authors concluded that intubation was easier using the GlideScope.43 In 20 1 3, Russell et al.44 reported a ran­ domized controlled trial which compared the GlideScope and the Macintosh laryngoscope for DLT intubation in 70 patients with no predictors of difficult laryngoscopy. The majority of the anesthetists who took part in the study had limited experi­ ence with the GlideScope for DLT insertion. All 35 patients in the Macintosh group were successfully intubated within rwo attempts, whereas in the GlideScope group, 29 patients were intubated on the first attempt with the GlideScope and three on a second attempt. In the remaining three patients, the Macintosh laryngoscope was used for the second attempt and was successful. The investigators encountered difficulty with tube delivery and advancement into the trachea. They concluded that the GlideScope was more difficult to use than the Macintosh for DLT intubation.44 Failure of DLT intuba­ tion using the GlideScope has also been reported.45 Shulman and Connell/6 used the Bullard laryngoscope in a group of 29 patients scheduled for general anesthesia and lung separation.

A DLT was successfully passed into the trachea in 28 of the 29 patients. Hirabayashi and Seo47 used the Airtraq laryngoscope to place #35 or 37 DLTs in 1 0 patients. Nine of the 1 0 patients had a CL Grade 1 to 2 view on DL with a Macintosh blade. Suzuki et al.48 reported the successful intubation of a patient with a #39 DLT using the Pentax AirwayScope with a modi­ fied blade. Poon and Liu49 used the AirwayScope to place an airway exchange catheter (AEC) into the trachea and then rail­ roaded a #37 DLT over the catheter under visual control using the scope. Intubation with a DLT using the Bonfils Intubation Fiberscope,50 the Wu scope,51 the CEL- 1 00 video-laryngoscope (Connell Energy Technology Co. Ltd., Shanghai, China) ,5 2 and the X-Lite (Rusch Tuttlingen, Allemagne)53 have also been reported. Retrograde intubation is an option in the clinical scenario presented here if the equipment and expertise are available.5455 Intubation with an SLT or AEC through a Laryngeal Mask Airway (LMA) or an Intubating Mask Airway (ILMA) is also an option. 56 Intubation by transillumination utilizing a lighted stylet is a nonvisual technique and is not recommended in the pres­ ence of pharyngeal masses or anatomic abnormalities of the upper airway.5758 However, successful placement of DLTs using a lighted stylet under general anesthesia in patients with pre­ dictors of difficult DL but without airway pathology has been reported. 36, 59,60 In the case presented here, a flexible bronchoscopic intuba­ tion under general anesthesia was attempted but the vocal cords could not be visualized. The glottis was visualized with the GlideScope but the larynx was noted to be "extremely anterior" and neither a "bougie" nor an ETT could be passed through the glottis because of the acute angle that needed to be negoti­ ated up into the larynx. An ILMA was placed and satisfactory ventilation was achieved. The flexible bronchoscope was passed through the ILMA but the vocal cords could not be identified. The patient was ventilated through the ILMA until the muscle relaxation could be reversed and then awakened. • What Should be the Next Steps in

Th is Patient's Management?

The patient requires urgent surgery. He was transported to the post-anesthesia care unit (PACU) for a period of observation. An explanation of the airway difficulty was provided to the patient, an antisialogogue was administered, and the patient was returned to the OR about 2 hours later for an awake flex­ ible bronchoscopic intubation. Awake flexible bronchoscopic intubation using an adult bronchoscope and an 8 . 5-mm ID SLT was performed under topical anesthesia (see Chapter 3) . A remifentanil infusion was used to attenuate airway reflexes. The awake intubation was uneventful and was followed by the controlled induction of general anesthesia. • Can Awake Flexible Bronchoscopic

I ntubation be Done with a DLT?

Successful awake flexible bronchoscopic intubation with a DLT has been reported by Patane et al. 37 The laryngeal and carina!

Lu ng Sepa ration in the Patient with a Diffi c u l t Ai rway

stimulation produced by the DLT can be intense and profound anesthesia of the airway is required.4•37 When the bronchial lumen of a DLT is ensleeved over the bronchoscope, only a short segment of the insertion cord of the scope remains out­ side the tube and maneuverability is therefore limited. 27·37 Once the DLT has been placed in the trachea, general anesthesia can also be induced before advancing the DLT into the mainstem bronchus under flexible bronchoscopic control. Since mod­ ern BBs have become available, awake flexible bronchoscopic intubation with a DLT or Univent is rarely performed.61 • What Are the Options for Lung Sepa ration

in Th is Case Now That an SLT Has Been Placed?

The options for one lung ventilation include use of a BB passed through the SLT or exchange of the SLT for either a Univent tube or a DLT using an AEC under visual control utilizing a video-laryngoscope. 2' 14'26.45 In the case presented, it was decided to proceed with the placement of a BB and not to exchange the SLT for a DLT. This decision was based on the degree of difficulty anticipated with the tube change and the risk associated with this maneuver, as well as the possibility of the requirement for postoperative ven­ tilatory support. A Fuji Uniblocker (Fuji Systems, Tokyo) was chosen and placed uneventfully in the left mainstem bronchus. The cuff was inflated under bronchoscopic control. The choice of BB is largely a matter of personal preference. The Fuji Uniblocker is made of silicone,5 is 66.5 em long, has an angled tip, and a spherical high-volume low-pressure cuff (cuff volume of 5-8 mL) .3 The adult blocker is 9 Fr and has a 2 mm lumen.3 It is maneuvered by rotation in a similar man­ ner to a bougie. Narayanaswamy et al.8 compared the Arndt wire-guided BB (Cook Critical care, Bloomington, IN) , the Cohen Flexitip BB (Cook Critical care, Bloomington, IN) , the Fuji Uniblocker, and the left DLT (Mallinckrodt Medical, Cornamaddy, Athlone, Westmeath, Ireland) in a randomized trial that included 1 04 patients undergoing left video or open thoracotomy. The three BBs provided surgical exposure equiva­ lent to the left DLT, although the blockers required more time to position and required intraoperative repositioning more often.8 In a randomized trial that compared the Coopdech blocker, the Arndt, the Univent tube, and the left DLT, Zhong et al. 1 2 reported that surgical exposure was similar among the groups. The first clinical use of a new BB, the EZ-Blocker (AnaesthetiQ, Rotterdam, The Netherlands) , was reported in 20 1 0 by Mungroop et al. 24 The blocker has a 4 em bifurcated tip each limb of which is fitted with a cuff. The blocker is posi­ tioned with one cuff in each mainstem bronchus and the cuff on the side to be blocked inflated. Lung collapse using the EZ-Blocker has been shown to be equivalent to that achieved with a DLT9'1 1 and the Cohen B B . 1 0 Th e surgical procedure required 8 hours t o complete. The estimated blood loss was 8000 mL. Eleven units of packed red blood cells, 1 500 mL of plasma, eight units of platelets, 6000 mL of crystalloid, and 1 5 00 mL of colloid were admin­ istered. At the end of the case, edema of the face and tongue was evident.

POSTOPERATIVE AI RWAY CO N S I D E RATIONS • Should Th is Patient be Extubated?

Airway edema can occur as a result of fluid resuscitation and trauma associated with the initial intubation. The presence of airway edema will almost certainly make reintubation condi­ tions even less favorable than they were at the beginning of the case. In addition, the patient has undergone an extensive surgical procedure and the risk of respiratory failure in the immediate postoperative period is significant. The placement of an epidural catheter for postoperative analgesia was not done on consideration of the preexisting neurological deficit and the planned spinal surgery. Placement of a paravertebral catheter could have been considered as an alternative. The BB was deflated and removed but the ETT was left in place. The patient was transported to the intensive care unit (ICU) in stable condition and electively ventilated. Twenty-four hours after the surgery the patient was awake and no longer required ventilatory support. • How Should the Patient be Extubated

at Th is Point in Time?

Whether the patient should be extubated in the I CU or in the 0 R is a matter of clinical judgment and to some extent dependent on the expertise and equipment available. Nasopharyngoscopy should be performed prior to extubation to determine the pres­ ence and extent of airway edema. The presence of an air leak around the tube (the leak test) may be reassuring. Given the degree of difficulty experienced with the intuba­ tion, the patient was transported to the OR for extubation. The extubation was performed over an AEC, being careful to match the numbers on the catheter with the numbers on the SLT. A surgeon skilled in the performance of a surgical airway was present in the room and the necessary equipment was immedi­ ately available. Extubation was uneventful.

OTH E R CO N S I D E RATIONS • If the SLT Had Been Exchanged for a DLT

After Induction, How Should This Have Been Done?

Tube exchange should be done utilizing an AEC and under visual control to assist guidance of the DLT through the glottis. 2 •3•26•62 The AEC should be introduced no further than 24 to 26 em from the teeth or lips in order to minimize the risk of trauma to the distal trachea and bronchi.3·14·26 An AEC at least 83 em in length is recommended for a DLT exchange. 26 This length of catheter best allows the depth of insertion to be controlled during the tube exchange. A video-laryngoscope should be used during tube exchange in either direction: SLT for DLT or DLT for SLT. Tube exchange using an AEC is not without risk. 2·63•64 McLean et al.64 reported a failure rate using the Cook Airway Exchange Catheter of 9.3% for SLT to SLT, 39.9% for SLT to DLT, and 0% for DLT to SLT. The number of cases in which direct or video-laryngoscopy was used to assist the exchange was not reported.

453

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Ai rway M a n a g e m e n t in the Operati n g Room

• If a DLT Had Been Used for Lung Separation,

What Constitutes Appropriate Airway Management at the End of the Case? Can the Patient Go to ICU with a DLT in Place?

Intubation was difficult at the start of the case. Given the extent and duration of the surgery and the likelihood of airway edema, exchange of the DLT for an SLT at the end of the case could be a highly dangerous maneuver.3 The glottis was visualizedwith the Glidescope at induction and the angle into the larynx was difficult to negotiate. The options then, are, to leave the DLT in place or perform a tracheotomy. If it is anticipated that the airway edema will recede in the immediate postoperative period and that prolonged ventilatory support will not be required, tracheotomy is not necessary at this time. Given the intraop­ erative course, placement of a BB through the SLT was a good decision and avoided the consideration of a potentially risky tube change at the end of the case. A DLT can be used in the critical care setting for one lung ventilation or for postoperative two-lung ventilation if tube change to an SLT is considered to be too risky. 14 However, ICU medical and nursing staff are generally less experienced in the management of a DLT. 1 ' 27 If the DLT is left in an endobronchial position, malposition can occur, particularly if neuromuscular blockade is not employed. 27 Alternatively, the DLT can be with­ drawn such that the endobronchial lumen is above the carina, and both lungs ventilated with both lumens with the bronchial cuff deflated. 14 Suction is more difficult through a DLT and secretions can be problematic. 27 In the postoperative setting, extubation directly from the DLT can be performed when the condition of the upper airway and ventilatory function are satisfactory, employing an AEC if appropriate. If more prolonged but short-term ventilatory sup­ port is anticipated, tube exchange to an SLT can be performed when the upper airway is favorable. If longer-term ventilation in anticipated, tracheotomy without a tube change may be more appropriate. • How Should the Ai rway Have Been Managed

if the Surgery Had Been an Emergency and Could Not be Postponed?

Intubation had failed by DL, GlideScope, flexible broncho­ scope, and via the ILMA. The expertise to perform a retrograde intubation was not available and the likelihood of success was uncertain given the airway pathology. If the neurologic deficit had been acute, then a tracheotomy could have been performed under general anesthesia with the patient ventilated via the ILMA. A BB could then be passed through an armored ETT or conventional tracheotomy cannula inserted into the trache­ otomy stoma. 14•26·65•66 If a wire-reinforced ETT had been used, it can be changed for a tracheotomy cannula at the end of the case. A conventional DLT can be inserted through a tracheotomy stoma if the caliber of the stoma is sufficient, or a DLT modified for use in tracheotomized patients (e.g., Tracheopart or Naruke tube) could be used.3·26'66-70 A conventional DLT placed through a tracheotomy stoma has been said to be prone to malposition26 as it is too long relative to the shortened upper airway and the tracheal cuff may be at or proximal to the stoma. 27 Cohen1 has

recommended that a rigid large diameter DLT not be passed through an old tracheotomy stoma. The Univent tube has also been inserted through a tracheotomy stoma to achieve one lung vemilation.71 , 72 Campos26 has recommended the use of an inde­ pendent BB for the patient with a tracheostomy tube in place. • If a "Can't I ntu bate, Can't Oxygenate"

Situation Had Occurred at Induction, What Should Have Been Done?

If ventilation by mask or EGD had become impossible dur­ ing the failed intubation attempts, emergency cricothyrotomy would have been indicated.3 The patient made an uneventful recovery. The diagnosis of lingual tonsillar hyperplasia was subsequently confirmed by an ear, nose, and throat consultant. No treatment was required.

S U M MARY Lung separation can be achieved using a DLT, the Univent tube, or a BB placed through an SLT. In the setting of a difficult air­ way, the decision to use a particular device must take into con­ sideration the airway anatomy and geometry, the expertise and equipment available, and the anticipated postoperative clinical course. Airway management decisions will depend on whether the difficulty is predicted or unpredicted and whether the surgery is elective or an emergency. In the management of the difficult airway, the first priority is to ensure adequate oxygenation and ventilation; one lung ventilation becomes a secondary objective.3 That said, in the setting of the difficult airway the use of an SLT and an independent BB can be an invaluable option.

REFERENCES I , Cohen E. Pro: The new bronchial blockers are preferable to double-lumen tubes for lung isolation. J Cardiothorac Vase Anesth. 2008;22 (6) : 920-924. 2. Cohen E. Recommendations for airway control and difficult airway man­ agement in thoracic anesthesia and lung separation procedures. Are we ready for the challenge? Minerva Anestesiol. 2009;75 ( 1 -2):3-5. 3 . Merli G, Guarino A, Della Rocca G, et al. Recommendations for airway control and difficult airway management in thoracic anesthesia and lung separation procedures. Minerva Anestesiol. 2009;75 ( 1 -2) : 5 9-78; 79-96. 4. Satya-Krishna R, Popat M. Insertion of the double lumen tube in the difficult airway. Anaesthesia. 2006; 6 1 (9) : 896-898. 5 . Campos JH. Which device should be considered the best for lung isolation: double-lumen endotracheal tube versus bronchial blockers. Curr Opin Anaesthesiol. 2007;20 ( 1 ) :27-3 1 . 6 . Campos JH, Kernstine KH. A comparison o f a left-sided broncho-cath with the torque control blocker Univent and the wire-guided blocker. Anesth Analg. 2003;96 ( 1 ) :283-289. 7. Campos JH, Massa FC. Is there a better right-sided tube for one-lung ventilation? A comparison of the right-sided double-lumen tube with the single-lumen tube with right-sided enclosed bronchial blocker. Anesth Analg. 1 998;86(4) :696-700. 8 . Narayanaswamy M, McRae K, Slinger P, et al. Choosing a lung isolation device for thoracic surgery: a randomized trial of three bronchial blockers versus double-lumen tubes. Anesth Analg. 2009; I 08(4): I 097- 1 1 0 1 . 9. Mourisse J, Liesveld J, Verhagen A, e t al. Efficiency, efficacy, and safety of EZ-Blocker compared with left-sided double-lumen tube for one-lung ventilation. Anesthesiology. 20 1 3; 1 1 8 (3) : 5 5 0-56 1 . I 0 . Kus A, Hasten T, Gurkan Y, Gul Akgul A, Solak M , Taker K. A comparison of the EZ-Blocker with a Cohen Flex-tip blocker for one-lung ventilation. J Cardiothorac Vase Anesth. 2 0 1 4;28 (4) :896-899. 1 1 . Ruetzler K, Grubhofer G, Schmid W, et al. Randomized clinical trial comparing double-lumen tube and EZ-Blocker for single-lung ventilation. Br J Anaesth. 20 1 1 ; 1 06 (6) : 896-902.

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Ai rway M a n a g e m e n t in the Operati n g Room 69. Saito T, Naruke T, Carney E, Yokokawa Y, Hiraga K, Carlsson C. New double intrabronchial tube (Naruke tube) for tracheostomized patients. Anesthesiology. 1 998;89(4): I 038- 1 039. 70. Yaney LL. Double-lumen endotracheal tube for one-lung ventilation through a fresh tracheostomy stoma: a case report. MNA j. 2007;75 (6) : 4 1 1 -4 1 5 . 7 1 . Andros TG, Lennon P F. One-lung ventilation i n a patient with a tra­ cheostomy and severe tracheobronchial disease. Anesthesiology. 1 993; 79(5): 1 1 27- 1 1 2 8 . 7 2 . Bellver J, Garda-Aguado R , De Andres J, Valia J C , Bolinches R . Selective bronchial intubation with the Univent system in patients with a tracheos­ tomy. Anesthesiology. 1 993;79(6) : 1 45 3 - 1 454.

C. increased rigidity and increased OD D. none of the above 39.2. Changing an DLT to an SLT at the end of the case can be difficult due to: A. edema B. previous intubation trauma C. suboptimal head and neck position D. secretions E. all of the above

SELF-EVALUATION QU ESTIO N S 39 . 1 . Why have the Univent and DLT been termed "difficult tubes" ?

3 9 . 3 . Exchange of an SLT for a DLT should be done: A. under visual control B. with an AEC

A. increased external diameter (OD)

C. with an AEC and under visual control

B. increased rigidity

D. none of the above

457

C H A PT E R 40

Airway Manage ment of a Patient with Superior Vena Cava O bstruction Syn drome Math ieu Asselin and Gordon 0. Launce/ott

CAS E PRESENTATION

457

I NTRO D U CTION .

457

PAT I E NT EVALUATI ON

458

S P EC I F I C CO NCERNS FOR THIS PATI ENT . . . . . . . . . . .

458

AI RWAY MANAG E M E NT . . . . . . . . . . . . . . . . . . . . . . . .

460

S U M MARY . . . . . . . . . . . .

46 1

SELF-EVALUATIO N Q U ESTI O N S .

462

CASE PRESENTATION A 5 5-year-old male patient with superior vena cava (SVC) obstruction secondary to a mediastinal mass is scheduled for bronchoscopy and mediastinoscopy. The patient weighs 1 20 kg (250 lb) and has obvious swelling of the face, neck, and upper extremities. The tongue is large (Mallampati Classification IV) and the oral mucosa is plethoric. He is unable to lie flat, but is not dyspneic in the sitting position.

I NTRODUCTION • What Is the Perti nent Pathophysiology

in SVC Syndrome?

The left and right subclavian and internal j ugular veins join to form the brachiocephalic (innominate) veins, which in turn join to form the SVC. Venous drainage from the head and upper extremities then finds its final conduit to the

heart in this large, but easily compressible, vessel. Extensive collaterals with the SVC include the azygos, the mammary, vertebral, lateral thoracic, paraspinous, and esophageal veins. The largest of these, the azygos vein, is formed from the j unction of the right subcostal and the right ascending lumbar veins. It ascends in the posterior mediastinum and then passes anteriorly over the right mainstem bronchus to join the SVC as the latter enters into the right atrium. Here, the area is anatomically crowded with lymph nodes, the pulmonary artery, and the tracheobronchial structures hemmed in by the sternum anteriorly. The low-pressure SVC can be obstructed, either indirectly by external compression from vascular structures, tumor, or enlarged lymph nodes or directly by primary or secondary intraluminal thrombus or tumor (Figures 40- 1 and 40-2) . Obstruction o f the SVC will result i n upper body venous hypertension, which forces blood to seek an alternate pathway to the heart via the previously described collateral vessels and the inferior vena cava. This upper body venous hypertension results in the classic clinical signs and symptoms of the syn­ drome. These include facial, neck, and arm swelling, as well as engorgement of the mucous membranes, including those of the upper airway. In some patients, it may result in laryngeal or cerebral edema, predisposing to an increased risk of surgical bleeding. Most cases of SVC syndrome are due to extrinsic tumor compression from bronchogenic carcinoma or non-Hodgkin's lymphoma occurring in the right paratracheal space or right pulmonary hilum. 1 From even a cursory glance at the anatomy, it is clear that the disease process may also compromise other major structures in the area, such as the pulmonary arteries, the right heart, and the tracheobronchial tree. With these factors in mind, the practitioner will want to determine the degree to which major structures are involved prior to embarking on induction of general anesthesia (GA) .

458

Ai rway M a n a g e m e n t in the Operati n g Room

Left internal j u g u l a r

subclavian brachiocephalic

A change in voice may be due to recurrent laryngeal nerve involvement or vocal cord edema. Dyspnea, often with a his­ tory of syncope, may not necessarily be due to airway compro­ mise but secondary to right ventricular outflow tract or right heart compression. 1 In this patient, the tongue is large, perhaps as a result of upper body venous hypertension, and the mucous membranes are plethoric, suggesting that the mucous membranes of the lar­ ynx in general, and glottis in particular, may also be engorged, edematous, and friable. • What I nvestigations Should be Done

to Assess the Ai rway of the Patient?

F I G U R E 40-1 . Th i s d i a g ra m i l l u strates the venous d ra i nage i nto the heart. (Reprod uced with perm ission from Abeloff M D. Clinical Oncology, 3rd ed. P h i l a d e l p h ia, PA: El sevier C h u rc h i l l Livi n g ston; 2004.)

\'\'\'.......---- S u perior vena cava

q-....� .3111 �-

Enlarged nodes or t u m o r b l ocking superior vena cava with azygos vein patent

.....,..� 30 kg·m - 2) has become much more fre­ quently encountered in the general population over the past decade. Mask-ventilation is often difficult in obese patients because of reduced chest compliance and increased intra­ abdominal pressure. The incidence of partially obliterated oropharyngeal structures in obese parturients is double that of non-obese parturients.6 In addition, weight gain may create a "short neck," a large tongue, and large breasts, all of which contribute to difficult laryngoscopy. In the morbidly obese par­ turient (greater than 1 40 kg or - 300 lb, BMI ;::: 4 0 kg·m- 2) , the risks for diabetes, hypertension, preeclampsia, and primary CD are all increased. There is also a higher incidence of dif­ ficult labor resulting in instrumental deliveries, postpartum hemorrhage, or other conditions which may require anesthetic intervention. 23 Morbidly obese parturients are at increased risks for anes­ thesia-related complications during CD, and increased risks for failed intubation and gastric aspiration if general anesthe­ sia is required. 24 The cesarean section rate in these patients can exceed 50%, with one-third of attempted tracheal intubations being difficult and 6% being failures. 2 5 In the ASA closed claims obstetrical files, damaging events related to the respiratory sys­ tem were significantly more common among obese (32%) than non-obese (7%) parturients.Z6 Res p i rato ry C h a n g es

Respiratory changes during pregnancy are of special significance to the anesthesia practitioner. Over the course of a normal ges­ tation, the parturient experiences a 30% to 60% increase in oxygen consumption, which results in an increased minute ven­ tilation. Displacement of abdominal contents toward the chest due to the enlarged uterus, causes a reduction in functional residual capacity (FRC) and premature airway closure, with widening of the alveolar-arterial oxygen gradient. The reduc­ tion in FRC, which begins to decline as early as the fifth month and is reduced to 80% of nonpregnant values by term, and together with the increase in oxygen consumption would lead to exceedingly rapid desaturation with apnea. The tendency toward rapid desaturation is further aggravated by a decrease in FRC in relation to the supine position and obesity. As a result of these changes, oxygenation of the mother and fetus may be compromised. 27 Despite adequate denitrogena­ tion, these physiological changes greatly reduce the time allow­ able for intubation post-induction. Ai rway C h a n g e s

Generalized edema may affect the oropharynx and nasophar­ ynx. These changes are aggravated by elevated estrogen levels that stimulate the development of mucosal edema and hyper­ vascularity in the upper airways. Capillary engorgement of the nasal and oropharyngeal mucosa begins early in the first trimester and increases progressively throughout pregnancy. Accordingly, the parturient frequently appears to have symp­ toms of upper respiratory infection and laryngitis, with nasal congestion and voice changes due to swelling of the false vocal

cords and arytenoids. Nasal obstruction from vascularity and edema may complicate bag-mask-ventilation (BMV) . 2 8 Numerous case reports suggest that edema of the pharyngeal and laryngeal structures (including vocal cords) may hinder visu­ alization of the cords and passage of an ETT. 29·30 Tongue edema may make retraction of the tongue into the mandibular space dur­ ing laryngoscopy difficult. The increased engorgement and vascu­ larity present special challenges in manipulating the nasopharynx (nasal trumpets, nasogastric tubes) , or when considering repeated attempts at intubation of the trachea. An ETT one size smaller than might be usual (i.e., 6.0-7.0-mm ID) should be routinely used. Excessive weight gain, even mild upper respiratory tract infections, pre-eclampsia, fluid overload, and bearing down, can all exacerbate airway edema-potentially leading to a severely compromised airway. The classical Mallampati classification (Samsoon and Young modification) of mouth opening has been reported to advance by one or two classes during pregnancy.6•14 This has been confirmed by acoustic reflectometry, which mea­ sures oropharyngeal volumes, and is likely a surrogate marker for ease of intubation of the trachea. It has demonstrated pharyngeal narrowing in pregnancy and labor, due to edema and an increase in localized fatty tissue volume.31 The Mallampati score may worsen even further as a consequence of bearing down, and the score may not return to the pre-labor state for a further 1 2 hours postpartum.32•33 Acoustic reflectometry also revealed decreased volumes both in women after delivery, and in women whose pregnancy was complicated by preeclampsia. 28•33·34 C a rd i ova scu l a r C h a n g es

The supine position may result in compression of the aorta and inferior vena cava (or both) by the enlarged pregnant uterus. Compression of the aorta decreases uterine blood flow, impair­ ing fetal oxygenation. Vena caval compression decreases venous return, cardiac output, and ultimately uterine blood flow. A com­ bination of oxygen desaturation and compromised cardiac out­ put is particularly lethal for the pregnant mother and fetus. This situation is further aggravated by obesity. It is therefore impera­ tive that the parturient be positioned with a wedge under the right hip, creating left lateral displacement of the uterus, away from the great vessels. Unfortunately, such displacement may hinder adequate preoperative airway evaluation and the creation of an optimum position for intubation of the trachea. Gastro i n testi n a l C h a n ges

The risk of aspiration in the parturient impacts how the anes­ thesia practitioner approaches and manages the parturient's airway. Several factors increase the risk of aspiration in these patients. While intragastric pressure increases steadily during pregnancy, as the gravid uterus enlarges, a concomitant decrease in lower esophageal sphincter tone occurs as circulating levels of progesterone increase. The enlarging uterus distorts esophageal and gastric anat­ omy. The cephalad pressure of the abdominal uterus decreases the obliquity with which the esophagus contacts the stomach, permitting reflux of gastric contents at lower than usual trans­ sphincteric pressure. Gastric emptying appears to be unaffected by pregnancy, though intestinal transit time and gastric acidity

What Is U n i q u e About the Obstetrical Ai rway

are increased. With the onset of labor, gastric emptying slows and this slowing may be further aggravated by the administra­ tion of opioids for labor pain management. Taken together, these gastrointestinal changes mandate that precautions for aspiration of gastric content be taken when a parturient undergoes general anesthesia. O bstetrica l Factors

There are a number of comorbid obstetrical factors that may put the parturient at risk for difficulties in airway management and related complications. Gestational hypertension, eclampsia, and preeclampsia aggravate mucosal and interstitial edema. 2 8 Concomitant proteinuria, with reduced intravascular plasma protein levels, leads to increased edema of the upper airway, an enlarged and less mobile tongue, and soft tissue deposition in the neck. Preeclampsia is frequently accompanied by coagulopa­ thy and edema, both of which may exaggerate bleeding with repeated attempts at direct laryngoscopy. Airway and laryn­ geal edema can develop exceedingly rapidly in preeclamptic patients, and neck and face edema, together with dysphonia from uvular edema, should alert the practitioner to the pos­ sibility of difficult intubation of the trachea.35 In these patients, extreme caution should be exercised not only at intubation, but at the time of extubation as well. Maternal knee-chest and left lateral positioning, as part of intrauterine fetal resuscitation for non-reassuring fetal heart tracings, may also limit ability to conduct adequate preopera­ tive airway evaluation. The impact that all these have on the validity, and the positive and negative predictive values of the preoperative airway assessment, is unknown. Massive peripartum hemorrhage (e.g. , placenta previa, accreta, abruption) and acute fetal distress (e.g., abruption, cord prolapse) are frequently encountered obstetrical emergen­ cies occurring acutely and unannounced. The visual impact of profuse vaginal bleeding, or the slow ominous sound of the tocodynamometer with fetal distress, frequently pushes obste­ tricians and anesthesia practitioners to urgently proceed to gen­ eral anesthesia, without taking the time to adequately assess the patient's airway. General anesthesia in the obstetric population is most frequently conducted for emergency clinical indica­ tions,36'37 and most airway catastrophes occur when the diffi­ cult airway is not recognized before the induction of anesthesia. Indeed, retrospective publications have reported poor ability to predict difficulty in the obstetrical population, and poor docu­ mentation of preoperative airway evaluation. 1 2' 19 Endler et al. 24 found that emergency surgery was implicated in up to 80% of maternal deaths with general anesthesia, and difficult or failed intubation was associated with 4 of 1 5 deaths.

AI RWAY EVALUATION • Why Is It I mporta nt to Assess the Airway of

Each Pa rturient?

Ideally, every pregnant patient admitted to the labor and delivery service should have a thorough preanesthetic airway evaluation. In the absence of this assessment, interdisciplinary education of

our obstetric, general practice, midwifery and nursing colleagues in airway assessment and the risk factors for difficult airways in parturients is imperative. With the always-present risk of acute onset fetal distress, an essential and critical part of airway man­ agement is an accurate assessment of the patient's airway. A detailed discussion of the airway examination and those predictors associated with management difficulties can be found in Chapter 1 . Most predictive studies have been conducted on general surgical populations, not parturients. Some 20 factors predicting difficult laryngoscopic intubation have been identi­ fied. The obstetrical patient presents unique assessment chal­ lenges, often the most important being a pressure of time. • How Do You Assess the Airway of a

Parturient? What Are the Predictors or Risk Factors of a Difficult Airway for a Parturient?

The increasing use of regional anesthetic techniques for delivery has significantly decreased opportunity for clinical studies in patients undergoing general anesthesia. While parturients pose many unique airway challenges to anesthesia practitioners, assessment of the pillars of airway management (BMV, the use of extraglottic devices [EGDs] , tracheal intubation under direct and indirect laryngoscopy, and establishment of a surgical air­ way) should not differ from the non-obstetrical population. Diffi c u lt BMV

As discussed, BMV can be difficult to impossible in approxi­ mately 0.02% of parturients. However, this incidence is com­ parable to the general surgical patient.8 While the mnemonic MOANS (see section "Difficult BMV: MOANS" in Chapter 1 ) i s a helpful reminder o f the five patient characteristics associ­ ated with difficult BMV,38 many of these characteristics do not apply to the obstetrical population. For example, young and healthy pregnant women are typically not older than 55 years of age, or edentulous, and they do not generally have facial hair. Obesity (BMI ;::: 30 kg·m- 2) , however, is an important consid­ eration and is becoming increasingly prevalent among pregnant women. It is noteworthy that 28% of pregnant patients and 75% of preeclamptic women reported snoring compared to 1 4% of nonpregnant women. 2 8 •

Difficult Direct Laryngoscopy and Tracheal Intubation Section "Difficult DL Intubation: LEMON" in Chapter 1 discusses in detail the current evidence in assessing the predictors of difficult direct laryngoscopy and intubation (LEMON) . Dupont and colleagues39 conducted one of the early airway studies in the obstetrical population, and reported that the risk of difficult direct laryngoscopic intu­ bation was eight times greater than in the general surgical population. This has since been disputed by Goldszmidt and others.9'15 Previously published increased rates of diffi­ cult and failed intubation in the parturient may in fact be related to anatomic abnormalities unrelated to pregnancy, augmented by emergency conditions, lack of preoperative airway assessment, or differences in intubation experience and expertise.9 The literature suggests a variety of clinical signs that can help determine the degree of difficult direct laryngoscopic

565

566

Ai rway M a n a g e m e n t in Obstetrics

TABLE 5 1 -2.

Risk factors

Featu res of the Ai rway Exa m i nation Usefu l

Class !

in Pred icti ng Difficult Laryngoscopy

I n the p a rtu rient

Class !I Class I l l

M a l l a m pati C l a s s I l l o r IV L i m ited thyromenta l d i stance S h o rt thick neck L i m ited mouth o p e n i n g Pro m i nent i n c isors

Class IV 1 + 5N I + PI I + RM 11 + 5N II + PI I I + RM 111 + 5N I I I + PI I I I + RM IV + SN

intubation (Table 5 1 -2) , however, none of these has a high positive predictive value as a single tool, particularly in the obstetrical patient. A number of studies have suggested that, although the presence of risk factors was useful, they were not as reliable as the Mallampati examination. Benumofl0 has frequently suggested that a patient's relative tongue/pha­ ryngeal size (Mallampati) , degree of atlanta-occipital joint extension, and adequacy of the mandibular space, provide the clinician with three easy to perform and accurate predic­ tors of difficulty in laryngoscopic intubation. Rocke et al.6 conducted one of the sentinel studies spe­ cifically looking at the obstetrical population and difficult airway predictors. They prospectively evaluated the airways of 1 5 00 parturients presenting for elective and emergency intubations, and found that a highly predictive sign for a difficult airway was a "neutral" to "extension" sternomental distance variation of less than 5 em. In addition, the authors built a scale of predictive factors showing clearly that the greater the number of abnormal findings, the higher the prediction accuracy for a difficult intubation (Figure 5 1 - 1) . Th e associated risk factors included short neck (SN) , pro­ truding maxillary incisors (PMI) , receding mandible (RM) , and Mallampati Class III and IV The relative risk of expe­ riencing a difficult intubation in comparison to an uncom­ plicated Class I airway assessment was as follows: Class II, 3 .23; Class III, 7 . 5 8 ; Class IV, 1 1 . 3; SN 5 . 0 1 ; RM, 9. 7 1 ; and PMI, 8 . 0 . Using the probability index for a combi­ nation of risk factors, Rocke et al. showed that a combi­ nation of either Class III or IV, plus PMI, SN, and RM, correlated with a probability of difficult direct laryngoscopy of > 90%. It was interesting that neither facial edema nor swollen tongue was associated with difficult laryngoscopic intubation. Overall, the mnemonic LEMON (see section "Difficult DL Intubation: LEMON" in Chapter 1) examines almost all of the difficult direct laryngoscopic intubation character­ istics (with the exception of the PMis) and remains a use­ ful guide for the obstetrical population. Obesity and BMI are not independent predictors of difficult intubation but an increased neck circumference is.41 In the obstetrical patient, obesity and large pendulous breasts often compound airway problems. It is important that the parturient be assessed in the recumbent position with left uterine displacement. Adjustments in the patient's position should be made before induction of anesthesia, to make intubating conditions easier, but there are limits to the extent that these adjustments can be employed, because of

IV + PI IV + RM I + S N + PI I + SN + RM I + RM + PI II + S N + PI I I + S N + RM II + RM + PI I l l + SN + PI I I I + S N + RM I I I + RM + PI IV + SN + PI IV + SN + RM IV + RM + PI I + SN + RM + PI I I + S N + RM + PI I l l + S N + R M + PI IV + S N + RM + PI

{29.3%)

{34.9%)

{ 1 5 .8%)

{3.7%) {2.1 %) {0.2%) {0.2%)

{5.7%) {0.3%)

{0.4%)

{5.4%)

{0.07%)

{0.07%) { 1 .2%)

{0.07%)

{0. 1 3%) {0%)

{0.07%) {0%)

{0.2%)

{0. 1 3%) {Oo/o)

{0.07%) {0%) {0%)

{0%) {0%) {0%)

{0%) {0%)

{0%)

{0%) 0

20

40

60

80

1 00

Proba b i l ity (%) of difficult i ntubation

F I G U R E 5 1 - 1 . The pro ba b i l ity of experi e n c i n g a d iffi c u l t l a ryngoscopic i ntu batio n for the va ryi n g com bi nations o f risk fa ctors a n d the observed i nc i d e n ce of these com b i nations. (Reprod uced with perm ission fro m Rocke D, M u rray W, Rout C, et al. Relative risk factors associated with d iffic u l t i ntu bation in o bstetric a n esthesia. A n esthesiology. 1 992;77:67-73 .)

•

the positioning required to reduce aortocaval compression. In the morbidly obese parturient, elevations (i.e., ramping) (see Figure 5 1 -2 and Chapter 20) of the thorax, shoulders, and head may be necessary to bring the anatomical axes of the oral, pharyngeal, and laryngeal structures into alignment. Positioning on a ramp and use of a short "stubby" laryngo­ scope handle may also mitigate the problem of the laryngo­ scope handle abutting on the patient's chest. Difficult Indirect Laryngoscopy and Tracheal Intubation Using Video-Laryngoscopes While section "Difficult VL Intubation: CRANE" in Chapter 1 discusses in detail the current evidence in assess­ ing the predictors of difficult indirect video-laryngoscopy and intubation (CRANE) , some of the predictors (e.g. , radiation to the head and neck) may not be applicable to the healthy obstetric population. Furthermore, there is limited clini­ cal information regarding the use of video-laryngoscopes in the obstetric population. In a retrospective review with 1 80 parturients, Aziz et al.43 showed that video-laryngoscopy resulted in 1 00% ( 1 8 out of 1 8) successful intubations on first attempt compared to 95% ( 1 57 out of 1 63 patients) with direct laryngoscopy. In a case series involving 27 obstet­ ric patients undergoing general anesthesia, Shonfeld et al.44 reported that video display from the CMAC provided better

What Is U n i q u e About the Obstetrical Ai rway

F I G U R E 5 1 -2. The Troop E l evation P i l l ow®: For i n d uction of genera l a nesthesia for obese, m o r b i d l y o bese a n d a l l parturient patients. These patients should be a p p ro p riately pre-positioned, for exa m p l e, "ra m ped" a s needed to e n s u re the patient's extern a l a u d itory meatus i s l evel with t h e ste r n a l notc h . (U sed with perm ission from CR Enterprises LLC, Fri sco, Texas.)

•

•

Cormack-Lehane grade ( 1 00% Grade I view) compared to standard direct laryngoscopy (52% Grade I, 44% Grade 2, and 4% Grade 3 and 4 view) . Similarly in a randomized trial involving 80 obstetric patients, Arici et al.45 reported that the McGrath Series 5 video-laryngoscope provided better views during orotracheal intubation compared to Macintosh laryn­ goscope even though the intubation was longer with the video-laryngoscope. While there is a growing interest in the potential use of video-laryngoscopes in the obstetric popula­ tion, more studies are needed to confirm their role in this patient population.46 Difficulty in Use of an EGD The latest iterations of obstetric difficult airway algo­ rithms advocate for even earlier use of an EGD as a part of a failed "Plan A" primary attempt at tracheal intuba­ tion. It also advocates that an EGD be used as an impor­ tant backup maneuver in "Plan B," and serve as a bridging attempt to reestablish gas exchange in a "can't intubate, can't oxygenate" (CICO) setting, while one prepares to perform a surgical airway (i.e., cricothyrotomy, tracheotomy, or "front-of-neck access [FONA]") in parturients. RODS (see section "Difficult Use of an EGD: RODS" in Chapter I ) is a mnemonic that i s intended to identifY patients where the use of an EGD may be difficult. Difficult Surgical Airway While the necessity to perform a surgical airway (i. e., cri­ cothyrotomy) in the obstetric population is exceedingly rare, all parturients requiring a general anesthetic ought to have an assessment of the feasibility of this procedure. The mnemonic SHORT (see section "Difficult Cricothyrotomy: SHORT" in Chapter I) can be used to quickly assess the patient for features that may indicate a difficult cricothyrotomy. In addition, given that the most common complication of this procedure is misplacement due to failure to identifY the cri­ cothyroid membrane (CTM) ,47 it would seem advisable to

identifY and mark the CTM ahead of time while in supine position (at preanesthesia assessment or pre-induction) in patients who have risk factors for an anticipated difficult airway.48 Identification of the CTM using digital palpa­ tion is more challenging in females (independent of body habitus) and in obese patients.49 The use of ultrasound to identifY the CTM has greatly improved accuracy, especially on obese patients, and given appropriate training, is poten­ tially an invaluable tool in this setting.49 Most obstetricians do not have experience in performing a surgical airway, and it is incumbent upon the anesthesia practitioner to maintain the necessary skills for this procedure despite their infrequent use. It may be prudent to consult with an experienced sur­ gical colleague for assistance when the need for a surgical airway is anticipated. When considering the best technique, studies have shown that use of a narrow-bore (::;2 mm) cannula technique has the highest failure rate, particularly in obese patients. Greater success is achieved by using a wide-bore (�4 mm) cannula technique (wire-guided Seldinger, or cannula-over trocar technique) , with the highest and most consistent success achieved by using an open surgical method.47•505 1 While many anesthesiologists are not comfortable with an open technique, the skills required for the rapid four-step cricothyrotomy (palpation, horizontal incision through skin and CTM, retraction of cricoid cartilage with hook [or inser­ tion of a gum-elastic bougie] , and insertion of tube) are easy to master.475 1 Alternatively, there is an argument for using a 4 em vertical incision for open cricothyrotomy in patients with a poorly identified CTM . 14 Nonetheless, success depends on not just having the practical skills, the correct equipment readily available, and trained assistance, but also on timely decision making. Regardless of technique used, failure to recognize immediate need (CICO) , and reluctance to per­ form cricothyrotomy, or other FONA can result in disastrous outcomes.47 When a Diffi c u l t La ryn g oscopy Is Antici pated i n a Pa rt u rie nt, I s I t Usefu l to Perfo r m a n Awa ke D i rect La ryn g oscopy (An "Awa ke Loo k") ?

Awake direct laryngoscopy with a topically anesthetized airway (i.e., an "awake look") has been suggested as useful assessment tool for the potentially difficult airway prior to induction of anesthesia. However, one must recognize that the airway, as it appears with the patient awake and un-paralyzed, might look quite different with the patient under general anesthesia and with muscle paralysis. 5 2

CON D UCT OF AN ESTH ESIA A N D TRAC H EAL I NTU BATION • What Are Necessary Preparations for

General Anesthesia for a Parturient?

Several preparations must be made on the labor and delivery suite to ensure safe and expeditious care of the parturient should general anesthesia be required. The operating room bed should have a ramp on it at all times (see Figure 5 I -2 and Chapter 20) .

567

568

Ai rway M a n a g e m e n t in Obstetrics

This will prove to be an invaluable aid in optimizing head posi­ tion and will help align the oral, pharyngeal, and laryngeal axes in the obese parturient. Furthermore, it will not be problematic in the patient with easy tracheal intubation. It is important to have all difficult airway equipment in the operating room. It is also important to recognize the importance of having well-trained assistants to help with all aspects of air­ way management, including rescue devices, as well as applica­ tion of cricoid pressure. Because time is often of the essence, and resources often limited, the practitioner must carefully choose devices with which they are familiar and comfortable, and tech­ niques that can be practiced regularly. Table 5 1 -3 details some of the suggested equipment necessary to manage the difficult airway on the labor floor. A short laryngoscope handle ("stubby") can be particularly helpful. While there are few prospective comparative studies on the obstetric airway and alternative airway equipment success rates, as previously stated, the most important success fac­ tor is practitioner familiarity and skills in using the devices. All obstetric patients requiring general anesthesia must receive aspiration prophylaxis (non-particulate antacid, H and 1 H blockers) . Induction should be in rapid sequence fashion, 2 including the application of cricoid pressure. However, conven­ tional teaching for obstetric RSI is being challenged. It has been shown that, even when correctly applied, cricoid pressure may not always be completely effective. 53 Consideration for discon­ tinuation of cricoid pressure is recommended should difficulty with BMV, laryngoscopy, or EGO insertion be encountered. The airway practitioner should consider gentle BMV ( 2 atte m pts. Hypoxe m ia-Sp0 < 90%; severe hypoxe m i a-S p0 < 70%. 2 2

Risk Ratio

647

648

Practical Consid e rat i o n s i n Ai rway M a n a g e m e n t

Hypoxe m i a

Reg u rg itation

I

Aspiration

D 1 990-95

>2 attem pts

• 1 995-2002

Surgical a i rway

1

F I G U R E 62- 1 . Co m p l ications associated with repeated atte m pts at l a ryngoscopic i ntu bation 9

the OR. The ready accessibility of difficult airway carts is indis­ pensable in reducing airway-related morbidity and mortality. • What Steps Should be Ta ken to Ensure That

the Carts Remain Well Stocked and Contain Eq uipment in Good Worki ng Order?

It is important that when an airway practitioner arrives at the scene of an airway emergency, or when the "Difficult Airway Cart" is summoned, all of the equipment that is needed must be present and functional. To achieve this, departmental and hospi­ tal policies or processes must be crafted, which should identifY: •

•

•

•

•

•

•

•

•

•

•

the numbers and locations of such carts; a process of annual review of the cart locations and how they are equipped and updated; a qualified staff member must be responsible for the cart in each assigned area as the "keeper of the cart"; how equipment is added to and deleted from the standard list of contents, and how such changes are suggested, vetted, implemented, and communicated to the relevant staff; how the drawers will be arranged and labeled; how equipment with schedules are to be maintained (e.g., bronchoscopes) ; time frames and responsibilities regarding replenishment after equipment is used; who will check the inventory and how often it will be checked. The checklist includes the functioning of essential equipment, such as bulbs and batteries, and time-sensitive supplies such as local anesthetic agents and vasoconstrictors; If cleaning is to be done, who will do it, how it will be done (e.g., bronchoscopes) , and how long the "out of service for cleaning" interval will be; an inventory of replenishment supplies to be kept immedi­ ately on hand, particularly disposables (e.g., EGOs, open cri­ cothyrotomy kit, etc.); where equipment manufacturers' literature will be kept.

Routine airway management equipment that one expects to use in most, if not all, airway management emergencies, such as laryngoscopes, airways, ETTs, intubating stylets (e.g. , Eschmann Introducer or Frova) , tonsil and catheter suction devices, etc., should be immediately available and not clutter the drawers of the cart. As mentioned above, this equipment

need not be on an OR cart as each anesthetizing location ought to have them available. Carts should be located in each area of the hospital where airway management might reasonably be expected to occur, such as EDs, coronary care unit, car­ diac catheterization units, labor and delivery suites, endoscopy suites, diagnostic imaging units, and other locations where sed­ atives will be administered. In locations where both children and adults are cared for, the pediatric cart should be distinctly separate from the adult cart (different style, and perhaps differ­ ent color) . An array of ETT sizes, masks, oral and nasal airways, etc. , must be easily accessible in the event pediatric patients are cared for. Perhaps the best system currently available to meet this need is the Broselow-Luten System0• 1 0 Alternatively, can­ vas-pocketed systems that are rolled up for storage can easily and quickly be unrolled to access the equipment. If at all possible, airway carts should be in a consistent location (e.g. , with the cardiac crash cart) . The cart should be secured with a plastic rwist removable lock. The cart is secured after each check, signaling that the cart has been replenished and is ready for use. The absence of the lock signifies that the cart needs immediate inspection. A keyed lock may be required for drawers that contain medications. The locking mechanism for this drawer must be limited to this drawer only and should not impede access to the other drawers with airway devices.

D I F F I C U LT AI RWAY CART I N TH E OR • What Are the Guiding Principles for

Establishing a Difficult Airway Cart for the OR Area?

Historically, the contents of the "difficult airway cart" in most anesthesia locations varied widely, as various practitioners demanded the addition of newer or their preferred devices. Unfortunately, items that nobody had ever used, or would ever use, were included. The contents would often be forgotten, and little or no maintenance would occur. Basically, they were difficult airway carts in name only. Although a number of publications describe difficult airway cart setup, most are simply a description of the author's depart­ mental cart. 1 1 However, such a list can be a good starting point for creating a useful cart, with the end users customizing the con­ tents according to departmental needs, preferences, and available

Diffi c u l t Ai rway Ca rts

resources. A designated individual or committee should be responsible for soliciting input from users in determining what should be on the cart. The decision about the contents ought to be reviewed quarterly or semiannually to ensure that carts have the most up-to-date and effective equipment. Deletions and addi­ tions need to be communicated to all users in a timely manner. In principle, the cart should be one that is easily accessible and has equipment familiar to the users and other unit per­ sonnel. An assortment of well-arranged and quickly accessible devices should be available to handle most needs. Decisions about disposable versus reusable equipment should be made consistent with hospital policies and published evidence of equipment effectiveness (discussed later in this chapter) . In this all-inclusive difficult airway cart, all equipment needed for difficult airway situations (so-called Plan B and Plan C) should be present. As mentioned, equipment on the cart need not duplicate routine airway equipment otherwise avail­ able on anesthetic carts in the ORs. This may be where an OR difficult airway cart differs from airway carts in other locations: in ICU or ED settings, airway kits or carts may contain both routine and alternative airway equipment. Familiarity with the difficult airway cart and its contents is cru­ cial. Using "difficult airway'' equipment for routine intubations will add to the skills in using alternative devices and will also help the anesthesia practitioner, and support personnel, gain needed familiarity with cart contents and location. This in turn will lead to more effective management of an emergency unanticipated difficult and failed airway, minimizing stress for all concerned. However, with regular use of the difficult airway cart, there must be a routine to ensure that it is properly maintained: disposables must be replenished and reusable equipment disinfected, and replaced as quickly as possible (see section "Disposable versus Reusable Devices Considerations for Difficult Airway Carts" in this chap­ ter) . This in turn implies that designated personnel familiar with the cart routinely check and replenish it. This is the same principle that applies to maintenance of the cardiac arrest "crash cart." • What Equi pment Should be Available on a

Difficult Airway Cart for the OR?

The cart containing the equipment should be mobile, small enough to be safely and easily moved by one person, and should fit into the ORs through the doorways. It should be located in a central location that is familiar and visible to all. Smooth cas­ tors on the cart and the drawers are important to ensure that the cart does not become an obstacle in itself, and is safe from being overturned. Cables and cords should be neatly attached so that nothing can be snagged while the cart is being moved or people are working around it. Failure to pay attention to this could lead to damage to equipment or injury to staff. The draw­ ers should be clearly labeled as per their contents. The equipment included on the cart should cover the range of options that might be needed in a difficult airway scenario. This will include categories such as: •

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equipment to facilitate mechanical (bag-mask or EGO) ventilation; adjuncts to direct and indirect laryngoscopy (e.g. , tracheal introducers) ;

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alternatives to direct laryngoscopy (e.g., video-laryngoscopes, lighrwands, etc) ; equipment to facilitate transtracheal access (e.g., cricothy­ rotomy kit) ; light sources, cameras, and monitors for techniques requir­ ing, or facilitated by, this equipment; equipment and drugs for application of topical airway anes­ thesia or airway blocks; miscellaneous equipment as determined by the location and facility.

• What Equi pment to Facilitate Mechan ical

(Bag-Mask or EGO) Ventilation Should be I ncl uded in the Difficult Airway Cart for the OR?

At least one bag-mask device should be available for delivery of positive pressure ventilation. Nonstandard mask sizes (i.e., very large and very small) may belong on the cart. The group or individual responsible for the airway cart should decide which EGOs to stock. If LMA Classic• or disposable LMAs are routinely stocked in an OR cart, then the cart may con­ tain an LMA ProSeal® and intubating LMA (LMA Fastrach•) . Other EGOs such as the King LT• airway can be considered, but the devices should be the ones with which the department members have experience and have found useful. Second­ generation EGOs (those with esophageal/gastric drainage tubes such as the King LTS-0•, LMA Proseal®, LMA Supreme®, LMA Protector'M, iGel•, etc.) should be considered, especially in the wake of the findings of NAP4 where aspiration was the most common cause of death.1 2, 13 • What Adju ncts to Direct Laryngoscopy

Should be Included in a Difficult Airway Cart for the OR?

An assortment of alternate blades designed to fit standard laryngoscope handles used in the OR should be available. For example, Miller (straight) and Macintosh (curved) blades of various sizes, as well as levering tip (McCoy) laryngoscope blades, might be kept in this section. The presence of a variety of ETTs (e.g., Endotrol'", Microlaryngeal Tubes'", GlideRite'") not routinely stocked in the OR, including a range of smaller sizes, is important. The presence of a flexible, Coude-tipped (distal 2 . 5 em angled approximately 35 degrees) Eschmann Tracheal Tube Introducer (the "gum-elastic bougie"), the SunMed Bougie'", Pocket Bougie, or the single-use Cook Frova'" is an essential addition to an emergency cart. It can be guided below the epi­ glottis when a Mallampati Class II or III view of the larynx is encountered, whereupon the ETT can be advanced over it (see section "What Is the Eschmann Tracheal Tube Introducer? How Does It Facilitate the Placement of an Endotracheal Tube?" in Chapter 1 2) . Because they should be kept straight (except the Pocket Bougie) , rather than bent to fit into a drawer, some tracheal tube introducers (e.g., Portex'") may be stored in their original shipping case, secured to the side of the cart (Figure 62-2) . As a simple, yet useful device, most would

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Practical Consid e rat i o n s in Ai rway M a n a g e m e n t

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F I G U R E 62-2. T h e proposed Diffi c u l t Ai rway Ca rt w i t h d ifferent d rawers for d iffere nt a i rway eq u i pme nt, video m o n itor, fl ex i b l e bro n c h oscope i n a sec u re com partment (A), a n d Esc h m a n n Tra c h e a l I ntrod ucer stored i n its orig i n a l s h i p p i n g case (B).

suggest that these introducers be an integral part of standard equipment found in every room or location where airways are routinely managed (e.g. , anesthetizing locations, ED resuscita­ tion rooms, etc.) . • What Alternatives to Direct Laryngoscopy

and Rescue Devices Should be Incl uded in a Difficu lt Ai rway Cart for the OR?

Here is where the list of objects becomes potentially extensive. Again, the principles are to not duplicate what already exists as routine airway management equipment in the OR, and to stock only those devices familiar to the anesthesia practitioner and support staff. Options for inclusion in this section are as follows:

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Intubating LMA (LMA Fastrach®) in a variety of sizes (#3--#5) , their dedicated silicone-ETTs (7-8-mm ID) , and the tube stabilizer to aid with subsequent LMA Fastrach® removal. Intubating lighted stylet for light-guided intubation. Flexible bronchoscope (FB) devices. The FB should be kept in a secure compartment, where it can be stored so that it is not tightly curled (Figure 62-2) . This ensures maximum pro­ tection of the fragile shaft and the motion cable that controls the scope tip. FBs ought to be handled with great care as they are fragile devices and repairs may be expensive. Discussion often arises regarding the use of pediatric versus adult scopes.

In a difficult intubation, particularly where failed attempts at direct laryngoscopy have traumatized the airway, the adult scope has the advantage of having a more functional suction lumen in addition to being a more rigid (and sturdy) scope. Ideally, a scope that will allow intubation with a 6-mm ID or larger ETT should be sought. Pediatric scopes are fragile and may not have the rigidity to facilitate the insertion of a large-diameter ETT tube around tight corners, and have smaller working channels compromising their suction capac­ ity. They are, however, indispensable in performing an awake nasal intubation and confirming the position of devices when lung isolation is required. Included in the drawer where the FB equipment is kept should be devices to protect the scope from being bitten, such as a Williams Airway Intubator'" (Figure 1 0-25), Ovassapian'" Fiberoptic Intubating Airway (Figure 1 0-26) , or Berman Intubating Pharyngeal Airways'" (Figure 1 0-23) in an assortment of sizes. Rigid fiberoptic and video-laryngoscopic devices. These devices provide indirect visualization of the larynx via fiberoptics, camera chips, or alternative visual displays (e.g. , Airtraq'" Optical Laryngoscope) . Some devices such as the McGrath Mac'", GlideScope'", and C-MAC" have a blade to aid with tongue control, while others, such as the Shikani SOS'", Clarus Video System'", Bonfils'", and Levitan FPS, are optical stylets, enabling visualization through an ensleeved ETT. Further details on these devices appear in Chapter 1 1 . Many of these devices can be operated with batteries, making them portable.

A recent review of the literature revealed that, although visualization of the glottic opening is improved with many of these devices, insertion of the ETT may remain problematic. 14 Indeed, significant trauma to the pharyngeal and tracheal structures has been documented with some of these devices. Intubations, when confronted by distorted anatomy, are facil­ itated more by some video-laryngoscopes than by others. In other words, none of the devices is a panacea. While video­ laryngoscopes are promising intubation devices, their precise role in difficult and failed airway management remains to be elucidated. • What Equi pment to Facilitate Transtracheal

Access Should be Available in the Difficult Ai rway Cart for the OR?

In a failed airway situation, particularly when ventilation and intubation are not possible, quick direct transtracheal access to the airway must occur (see Chapters 1 4 and 1 5 for details) . It is safe to say at this point in time that OPEN Cricothyrotomy is indicated in the "can't intubate, can't oxygenate" (CICO) failed airway; and that transtracheal jet ventilation should be aban­ doned. 15 Commercial kits are available with equipment for one or both techniques. The Universal Cricothyrotomy Kit'" avail­ able from Cook Critical Care contains both open and Melker (needle cricothyrotomy) equipment. These cricothyrotomy kits now have cuffed cannulae, making them particularly use­ ful when faced with the need for positive pressure ventilation. For those departments with members familiar with the tech­ nique, equipment for retrograde intubation can be considered

Diffi c u l t Ai rway Ca rts

an option in less urgent situations (e.g. , "can't intubate, but can oxygenate" situation) . The equipment for retrograde intubation is also available commercially in a kit (Cook Critical CareTM) .

practices are essential in ensuring that vital life-saving equip­ ment is available and in working order when required, includ­ ing the following: •

• What Video Accessory Eq u i pment

Should be Available in the Difficult Airway Cart for the OR?

Many of the newer flexible bronchoscopes can run on a battery-powered light source, while visualization occurs through a traditional eyepiece. Other FBs and the newer video bronchoscopes require a separate light source that attaches to the scope via a cable. This light source is generally brighter than the battery-powered light sources. A particularly useful device is a camera with an appropriate adapter that attaches to a bronchoscope's eyepiece to give a video feed to a monitor (see Figure 62-2) . This allows much better viewing of the airway, as the image is magnified and is brighter than that viewed through the eyepiece. It allows an assistant to visualize what is happen­ ing and in a teaching institution, it can be invaluable when explaining or directing a trainee what to do next. Still or video images can be recorded for documentation of the procedure as well as any pathology encountered. • What Other Miscella neous Equipment

Should be Available in a Difficult Airway Cart?

Ancillary equipment, such as medication cups for holding and mixing solutions, tongue depressors, tonsil forceps (e.g., the Kraus or Jackson forceps) for applying local anesthetic (e.g., lidocaine) containing gauze balls for superior laryngeal nerve blocks, as well as antifog agents for the FBs are a few other additions to the cart. The need for awake intubation is always a possibility, so appropri­ ate types and volumes of local anesthetic agents should also be kept on the cart (see Chapter 3). Water-soluble lubricants (e.g., AMG MedPro Lubricating Gel; AMG Medical Inc., Montreal, Canada), silicone fluid (Endoscopic Instrument Lubricant, ACMI, Norwalk, CT), or other antifog agents should also be available. An array of airway exchange catheters is always appropriate, for use in changing tubes in difficult situations or for the extu­ bation of the patient whose trachea was difficult to intubate. Availability of pediatric equipment will be dictated by the practice pattern of the hospital, although very small-for-age adults, disaster preparedness, and airway pathology situations make it advisable for adult hospitals to carry some pediatric equipment. Other equipment for inclusion on the difficult airway cart will be dictated by the department's practice envi­ ronment. For instance, some institutions include rigid bron­ choscopes and anterior commissure scopes on their cart.

D I F F I C U LT AI RWAY CART OUTS I D E THE O R • How Might Equipment Requirements Differ

for Out-of-OR Locations Such as the ICU or ED and Why?

The processes governing airway carts in non-OR areas are no different than those described above. A variety of policies and

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Who should be involved in deciding what the cart contains? How are suggestions as to contents made and how are those decisions made? How are cart modifications communicated effectively to all staff that may be affected? How often is the cart checked for contents and equipment function, and by whom? Who is responsible to ensure that the carts are restocked rou­ tinely after use? How is this process documented?

Some areas are more "airway intervention prone" than oth­ ers. EDs, CCUs, free-standing day-surgery operations, PACUs, pediatric dental clinics, nonhospital surgical facilities, and pedi­ atric cancer care units are obvious examples. It is reasonable to expect that airway intervention may occur with some regularity in these environments, and that routine and difficult airway management equipment ought to be immediately available. Others are less obvious. These include units where proce­ dural sedation is undertaken, such as endoscopy suites, angiog­ raphy and cardiac catheterization units. While routine airway management equipment ought to be immediately available on these units, it may be financially prohibitive to create potentially expensive, fully equipped carts as described above. However, it is not unreasonable to expect that such units have relatively inexpensive, proven adjuncts, such as oral and nasal airways, and rescue devices such as disposable LMA (LMA Unique®) , LMA Fastrach®, and intubating stylets. Some institutions designate staff from anesthesia, criti­ cal care, or emergency medicine, or hospitalists be a part of a team that responds to declared intra-institutional airway emer­ gencies. In response, some of these departments have created portable airway management bags to be taken to the site of the airway emergency. Policy considerations as to contents and their working order are no different for these kits than for the cart described above. Furthermore, and crucially important from a medicolegal perspective, is the involvement of those departments tasked with emergency airway management in the design, equipping, and maintenance of unit resident carts in the units for which they are responsible. It is the duty of the hospitals and unit management, department leadership, and airway practitioners to understand and embrace this accountability.

DISPOSABLE VERS U S REUSABLE DEVICES: CON S I D E RATIONS FOR D I F F I C U LT AI RWAY CARTS • What Is Transm issible Bovine Spongiform

Encephalitis (BSE)? Should Airway Practitioners be Concerned About It?

The widespread awareness of the possibility of transmission of infectious processes via the use of reusable medical equipment has led to adherence to standards for sterilization as a routine

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practice. Until recently, it was assumed that the adherence to these traditional sterilization measures would assure that pre­ vention of iatrogenic disease transmission by this route would be effective. Creutzfeldt-Jakob disease (CJD) , bovine spongiform enceph­ alitis (BSE or mad cow disease) , as well as variant CJD (vCJD) are examples of transmissible spongiform encephalopathies (TSE) . All of these diseases are transmitted by malformed pro­ tein particles, referred to as prions. These infectious prion pro­ teins attach themselves to native prion proteins in the recipient's brain, resulting in production of more of the distorted, abnormal prions, and the clinical specter of progressive neurological symp­ toms leading to death. Almost any symptom can present, from motor, to sensory, to cognitive dysfunction. This often makes the diagnosis difficult, as the symptoms can be confused with other neurological conditions. Definitive diagnosis is made histologi­ cally by biopsy or at autopsy. The term "spongiform" refers to the spongy gross appearance of the brain caused by TSE. The incidence of TSE in humans is extremely low. Sporadic (90% of CJD) and familial ( 1 0% of all CJD) forms of CJD occur at a frequency of 1 : 1 ,000,000 in the general popula­ tion. Iatrogenic forms of CJD have occurred from transfer of infected neural tissues (pituitary extract, cornea, or dura mater) and represent < 1 % of all cases of CJD . I n 1 986, the first case of B S E was reported i n Britain. By 200 1 , it was estimated that 1 80,000 cattle were infected. One recalls the widespread control measures taken at that time, with the mass destruction of herds throughout the United Kingdom. There appears to be a link between BSE and vCJD. This variant has some significant differences from the sporadic form of CJD. Among the differences between the two disease entities is the notable discovery of a prion specific to vCJD in lymphoid tissues (tonsil, spleen, appendix, and lymph nodes) . Prior to this, the only location of the agents responsible for BSE was felt to be neural tissue involving brain, spinal cord, dura mater, or eye. The discovery of prions in lymphoid tissue occurs very early in the disease process, before the onset of clinical symptoms. Furthermore, the tissues are very highly infectious. A mass of 1 j.lg of infected lymphoid tissue has the same risk of infectivity as 1 g of neural tissue from sporadic CJD-infected subjects . 16•17 This makes the tissue infected with the vCJD prion particle 1 000 times more infectious. By the year 2002, a total of 1 34 cases of human TSE felt secondary to BSE had been reported worldwide . 16 The vast majority ( 1 26) were in the United Kingdom and Ireland, six in France, one in Italy, and one in the United States. The US (FL) resident, however, was from the United Kingdom and it was felt the disease had been acquired there. Clearly, the transmis­ sion of TSE has been documented through the use of neural tissues, both dural grafts and pituitary growth hormone. It has also been reported to have passed from patient to patient via reusable neurosurgical instruments, despite employing standard cleaning and disinfection methods. While it is difficult to assess the risk of transmission via reusable airway instruments, either surgical or anesthetic, that have come in contact with lymphoid tissue in an infected patient, the infectivity of the vCJD prion from such tissue as mentioned above, is approximately 1 000 times that of the material from neural tissue. In spite of the

above data, there have been no reported cases, to date, of vCJD transmitted via contaminated airway equipment. Furthermore, projections of the future risks of deaths from vCJD show dra­ matic decreases, such that the incidence of deaths from the dis­ ease will be almost negligible over the next 70 years. 18 • How Effective Is Sterilization in Destroying

the Prion Pa rticle?

Discovery of prion transmission through the use of infected sur­ gical instruments created an alarming realization that the usual methods of sterilization were not reliable in disinfecting medical equipment. 1 9• 20 It has been shown that the prion particles associ­ ated with TSE are extremely resistant to accepted standard steril­ ization procedures; particles withstanding autoclaving ( 1 20oC) , ultraviolet radiation, as well as ionizing radiation. 20 The dis­ covery that protein residue is present in medical instruments used for airway manipulation after routine cleaning procedures creates even more concern. This is particularly worrisome in light of the presence of prions in lymphoid tissues in patients later diagnosed with vCJD. Miller et al. 2 1 showed, in the assess­ ment of 20 cleaned reusable LMAs, that all had residual protein deposits on them, ranging from mild (55%) to heavy staining (20%) . Similarly, of the 6 1 used laryngoscope blades that had been cleaned and returned for use, 50 were contaminated. This finding was confirmed by Clery and colleagues. 22 The recognition that: (i) prions related to vCJD were present in tonsil tissue; (ii) the specific prion was much more virulent than the agent for vCJD; and (iii) material from patients was present on airway instruments in spite of adequate techniques of sterilization has led to the suggestion that single-use instruments be used in place of reusable varieties, where the risk of cross contamination with tonsil tissue can occur. Indeed, in 200 1 , the Department of Health in the United Kingdom mandated the use of disposable surgical and anesthetic instruments for use in tonsil surgery. However, within a year, the high incidence of surgical complications deemed to be secondary to the introduc­ tion of these disposable instruments led to the reversal of the directive. It was decided that the risk of complications from the disposable instruments outweighed the risk of transmission of vCJD from cross contamination of inadequately cleaned mul­ tiple use instruments. Although the ban on reusable anesthetic equipment was initially lifted, it was reimposed in 2002. • How Well Do Single-Use (Disposable) Airway

Devices Work When Compared to the Reusa ble Instruments?

Following the concern that reusable airway equipment could cause the transmission of vCJD, a large number of single-use instruments were introduced into the market. These included, but were not limited to, laryngoscope blades, tracheal tube introducers (e.g. , Eschmann Introducer) , LMA, and other EGDs, as well as disposable covers for laryngoscope blades. However, there are no strict testing or standards that must be met by any of these devices. Consequently, a great deal of con­ troversy has arisen as to their effectiveness, when compared to the traditional equipment.

Diffi c u l t Ai rway Ca rts

Twigg et al. 23 compared six single-use laryngoscope blades with the "standard" Macintosh blade in a simulator model. Twenty experienced anesthesiologists used each device, both in an "easy" scenario and a simulated difficult airway. Time to intu­ bate, need for the use of an Eschmann Introducer, Cormack/ Lehane (C/L) grading, and percentage of glottic opening vis­ ible (POGO) scores were recorded. Although considerable variability existed between the disposable devices, the best performer in both "normal" and "difficult" scenarios was the Macintosh blade. Not surprisingly, it was the difficult airway that brought out the greatest differences between the best and the worst performers. Some of the single-use blades performed reasonably well, the best being the Europa, which is a metal instrument. The results were so troubling that the investigators concluded, "We believe that intubation equipment that fails to match standard equipment should be avoided and is clinically unsafe. The unregulated use of single-use laryngoscopes must be questioned." 2 3 Annamaneni et al. 24 demonstrated a difference between single­ use and disposable tracheal introducers ("bougies") in simu­ lated difficult intubations. Twenty anesthesiologists attempted intubation twice with both a reusable introducer and a single­ use introducer, with success measured by tracheal as opposed to esophageal insertion. The success with first attempts was 85% versus 1 5% for the multiple use and disposable devices, respec­ tively. The results were similar for the second attempt. Evans et al. 2 5 compared disposable and non-disposable laryn­ goscopes by studying the time to intubate as well as measuring the force used to obtain an adequate laryngoscopic view, for both routine and difficult intubation in a manikin. They had 60 anesthesiologists performing intubations with five different laryngoscope blades, both routinely and with a cervical collar on the manikin. The blades included the standard Macintosh #3, a disposable metal, and three plastic blades. The time was significantly greater with the plastic blades when compared to the metal, for both the routine and "difficult" intubations. The increase ranged from 33% to 85%. Forces generated were sta­ tistically greater for the plastic blades when compared to those for the metal blades, by as much as 35%. The forces generated, even though they were not out of the range used clinically, were sufficient to cause three of the plastic blades to fracture during the study. Anderson and Bhandal26 measured the effect on the illumi­ nation by placing a protective cover over a reusable Macintosh blade. They showed that a predictable reduction in illumination occurred, with a mean reduction of 1 9%. Others have com­ mented on their findings that disposable laryngoscope blades are inferior to reusable devices. 27• 28 One of the authors of this chapter (SP) had the experience of having been provided with a disposable plastic blade in the ICU when called to assist with a failed intubation. The blade fractured during the intubation attempt, causing a laceration on the patient's tongue and adding to an already stressful situ­ ation. Intubation was successful following the use of a reusable metal Macintosh blade. Another area where the influx of single-use, disposable devices has flooded the market place is with the LMA The reasons cited are again cost as well as infection control.

The significant increase in the marketing of these devices is unfortunately devoid of studies showing their safety and reli­ ability. The materials used differ significantly from the ones used in the original LMA Classic". In the LMA Classic" device, silicon was the chosen material. It produces a good seal, due to its pliability. It is, however, more expensive than the poly­ vinylchloride (PVC) material used in the single-use devices. Of note, Dr. Archie Brain rejected PVC as the materials for his LMA devices in the development stages. PVC, by its nature, is a rather rigid material, and therefore not very compliant. Plasticizers are needed to make PVC pliable and therefore pro­ duce a decent seal. These additives, however, potentially can make these products toxic, as phthalates-the most commonly used plasticizer-have been suggested as being potentially car­ cinogenic. Another concern regarding the use of single-use devices is the effects on the environment with the disposal of these nonbiodegradable plastic products. Most importantly, there is a lack of standardized guidelines for the manufacturing of disposable devices, as well as the lack of studies comparing their efficacy to the original, reusable LMA devices. Just as with the disposable laryngoscopes and tracheal introducers, studies may reveal that the performance and safety of these devices may or may not meet expectations. • Should Reusable or Disposable Eq u i pment

be Kept in the Difficult Airway Carts?

The only reliable ways to avoid the transmission of vCJD is to either use disposable instruments or not perform airway manipulation on patients infected with prion agent, and thus avoid contamination of reusable equipment. Clearly, the risk of contaminating equipment depends on the probability of caring for an infected individual. The data from the World Health Organization (WHO) show that the incidence varies world­ wide and is very low, even in countries at highest risk (i.e., the United Kingdom) . Indeed, the risk of transmission through the use of contaminated instruments was felt to be less than the risk of complications posed by disposable surgical instru­ ments used for tonsillectomy in 200 1 . Fortunately, the risks of anesthetic-related airway mishaps are lower than the risks posed by complications from our surgical colleagues. The numbers of failed intubations are too low to have adequate power to reveal what the increased risks posed are to patients by using dispos­ able devices. Certainly, the risk posed by cross contamination of vCJD is unknown. However, as discussed earlier, there has not been a single reported case of transmission of vCJD via airway equipment at the time of this publication. In their edito­ rial, Blunt and Burchett16 discuss the hypothetical relative risks and come to the conclusion that the risk to the patient with poorly functioning airway equipment is likely greater than that of acquiring TSE through contaminated airway instruments. The cost and reliability must be taken into account for all single-use instruments. Although Galinski et al. 29 felt that the disposable instruments were acceptable, they also state that, "it may be advisable to maintain conventional laryngoscopes in reserve for difficult intubations." More effective cleansing meth­ ods would also reduce risk, albeit not eliminate it. In the final analysis, it is important to weigh the relative risks of possible

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contamination with vCJD prions, negligible in most areas of the world and dropping, to those of risks created during airway man­ agement with what could, and has been shown to be, less than optimal equipment. The decision to keep reusable or disposable equipment in the difficult airway carts should be based on sound scientific evidence, relative risk, and cost-benefit assessments. Unfortunately, a lack of studies supporting the efficacy and safety of the large number of disposable airway devices flooding the market is concerning, making informed decision difficult. Furthermore, many of the comparative studies have shown that these disposable devices are frequently substandard when com­ pared to their reusable counterparts. The issue of cost, discussed by Cook30 in an editorial in the BJA suggests that this may not be the advantage as previously thought. Finally, when dealing with the most difficult airway situa­ tion, where the emergency airway cart is required, one could argue that the best, most reliable, and proven equipment should be selected.

S U M MARY The use of alternative airway devices has clearly improved patient care. The ready availability of these devices is markedly facilitated by the creation of an airway cart. This cart should be easy to use, well laid out, and maintained to ensure optimal use. The contents should encompass a range of devices as described in various publications, and should be customized to the needs of a given department and its members. Although the decision to keep reusable or disposable equipment in these airway carts is not an easy one, it should be based on relative risk, scientific evidence, and the cost-benefit assessments. The appendix itemizes how a difficult airway cart might be structured.

REFERENCES I . American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Practice guidelines for rhe difficult airway. Anesthesiology. 1 993;78 : 5 97-602. 2. American Society of Anesthesiologists Task Force on Management of rhe Difficult Airway. Practice guidelines for management of the difficult airway: an updated report by rhe American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology. 2003;98: 1 269- 1 277. 3. Crosby ET, Cooper RM , Douglas MJ, et al. The unanticipated dif­ ficult airway with recommendations for management. Can J Anaesth. 1 998;45 :757-776. 4. Practice guidelines for management of the difficult airway: an updated report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology. 20 1 3; 1 1 8 :25 1 -270. 5 . Frerk C, Mitchell VS . McNarry AF, et al. Difficult Airway Society 20 1 5 guidelines for management o f unanticipated difficult intubation i n adults. Br J Anaesth. 20 1 5 ; 1 1 5 : 827-848. 6 . Rose DK, Cohen MM. The airway: problems and predictions in 1 8,500 patients. Can ] Anaesth. 1 994;4 1 :372-3 83. 7. Schwartz DE, Matthay MA, Cohen NH. Death and other complications of emergency airway management in critically ill adults. A prospective investigation of297 tracheal intubations. Anesthesiology. 1 995;82: 367-376. 8 . Mort TC. Emergency tracheal intubation: complications associated with repeated laryngoscopic attempts. Anesth Analg. 2004;99:607-6 1 3, table of contents. 9. Mort TC. The incidence and risk factors for cardiac arrest during emer­ gency tracheal intubation: a justification for incorporating the ASA guide­ lines in the remote location. J Clin Anesth. 2004; 1 6 : 508-5 1 6. 1 0 . Luten R, Broselow J. Rainbow care: the Broselow-Luten system. Implications for pediatric patient safety. Ambul Outreach. 1 999: 1 4- 1 6.

1 1 . McGuire GP, Wong DT. Airway management: contents of a difficult intu­ bation cart. Can J Anaesth. 1 999;46: 1 90- 1 9 1 . 1 2 . CookTM, Woodall N , Frerk C . Fourrh National Audit Project. Major com­ plications of airway management in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society. Part I : anaesthesia. Br J Anaesth. 20 I I ; I 06:6 1 7-63 1 . 1 3 . Cook TM, Woodall N , Harper J , et al. Fourth National Audit Project. Major complications of airway management in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society. Part 2: intensive care and emergency depart­ ments. Br J Anaesth. 20 1 1 ; 1 06:632-642. 14. Niforopoulou P, Pantazopoulos I, Demestiha T, Koudouna E, Xanthos T. Video-laryngoscopes in the adult airway management: a topical review of the literature. Acta Anaesthesia! Scand. 20 I 0;54: I 050- 1 06 1 . 1 5 . Duggan LV, Ballantyne Scott B, Law JA, Morris IR, Murphy MF, Griesdale DE. Is transtracheal jet ventilation an effective management technique in the "can't intubate can't oxygenate" emergency? A systematic review. Br J Anaesth. 20 1 6; 1 1 7:28-38. 1 6. Blunt MC, Burchett KR. Variant Creutzfeldt-Jakob disease and disposable anaesthetic equipment-balancing the risks. Br J Anaesth. 2003;90: 1 -3. 1 7 . Bruce ME, McConnell I, Will RG, Ironside JW Detection of vari­ ant Creutzfeldt-Jakob disease infectivity in extraneural tissues. Lancet. 200 1 ;358 :208-209 . 1 8 . Ghani AC, Donnelly CA, Ferguson NM, Anderson RM . Updated projec­ tions of future vCJD deaths in the UK. BMC !nfoct Dis. 2003;3:4. 1 9. Brown P, Preece M, Brandel JP, et al. Iatrogenic Creutzfeldt-Jakob disease at the millennium. Neurology. 2000; 5 5 : 1 075- 1 08 1 . 20. Zobeley E , Flechsig E , Cozzio A, Enari M , Weissmann C . Infectivity of scrapie prions bound to a stainless steel surface. Mol Med. 1 999;5 :240-243. 2 1 . Miller DM, Youkhana I, Karunaratne WU, Pearce A. Presence of pro­ tein deposits on 'cleaned' re-usable anaesthetic equipment. Anaesthesia. 200 1 ;56: 1 069- 1 072. 22. Clery G, Brimacombe J, Stone T, Keller C, Curtis S . Routine cleaning and autoclaving does not remove protein deposits from reusable laryngeal mask devices. Anesth Analg. 2003;97: 1 1 89- 1 1 9 1 . 23. Twigg SJ, McCormick B , Cook TM. Randomized evaluation o f the perfor­ mance of single-use laryngoscopes in simulated easy and difficult intuba­ tion. Br J Anaesth. 2003;90:8- 1 3 . 24. Annamaneni R , Hodzovic I, Wilkes AR, Latta IP. A comparison o f simu­ lated difficult intubation with multiple-use and single-use bougies in a manikin. Anaesthesia. 2003 ; 5 8 :45-49. 2 5 . Evans A, Vaughan RS, Hall JE, Mecklenburgh J, Wilkes AR. A compari­ son of the forces exerted during laryngoscopy using disposable and non­ disposable laryngoscope blades. Anaesthesia. 2003 ; 5 8 : 869-873. 26. Anderson KJ, Bhandal N. The effect of single use laryngoscopy equipment on illumination for tracheal intubation. Anaesthesia. 2002;57:773-777. 27. Babb M, Mann S. Disposable laryngoscope blades. Anaesthesia. 2002;57:286-288. 28. Jefferson P, Perkins Y, Edwards VA, Ball DR. Problems with disposable laryngoscope blades. Anaesthesia. 2003 ; 5 8 :3 8 5-386. 29. Galinski M, Adnet F, Tran D, et al. Disposable laryngoscope blades do not interfere with ease of intubation in scheduled general anaesthesia patients. Fur J Anaesthesia!. 2003;20:73 1 -73 5 . 3 0 . Cook T M . The classic laryngeal mask airway: a tried and tested airway. What now? Br J Anaesth. 2006;96 : 1 49- 1 52.

SELF-EVALUATION QU ESTIONS 62. 1 . Which o f the following i s a known effective method of sterilization in destroying the prion particle? A. autoclaving ( 1 20°C) B . ultraviolet radiation C. ionizing radiation D. sterilization with ethylene oxide E. none of the above 62 .2. All of the following policy issues regarding a difficult air­ way cart are crucial EXCEPT A. cart location B. who is the cart "policy'' manager

Diffi c u l t Ai rway Ca rts

C. communications regarding contents D. maintenance and replacement of contents E. who is permitted to use the cart 62. 3 . Since anesthesia practitioners are called to out-of-OR locations to manage airways A. they are liable for negative outcomes if the equipment they need is not available

C. they must ensure that policies regarding airway equipment maintenance in out-of-OR locations are in force and followed D. noncompliance in any of the scenarios listed above (including the availability of essential equipment) would be grounds to refuse to participate in airway management in those locations E. all of the above

B. they must have input regarding contents of difficult airway carts in locations where they may be called to intervene

APPEN D IX: SAM PLE CONTE NTS OF AN OPERATI N G ROOM D I F F I C U LT AI RWAY CART D rawer # 1 : awa ke i ntu bation and to pica l a n esthesia

D rawe r #2

D rawer #3 Drawer #4: LMAs Drawer #5 : s u rg ica l a i rway DRAWER #6: b ro n c h oscope To p of ca rt S i d e ca b i n et

E n dosco pic i ntu bation g u ides s u c h as Ovassa pia n™, Wi l l i a m s™, a n d/o r Be r m a n I nt u bati n g P h a ry n g e a l ( B rea kaway) Ai rways™ M u cosa l Ato m izati o n Device (MADTM) Antifog g og g l es J a c kson C rossove r Force ps Ato m ize r (e.g., s i n g l e- u se EZ-Sp rayTM Al cove M e d i c a l Corporation, H o u sto n, TX) with 0 2 Tu b i n g Phenyl e p h r i n e 0 . 5 % (N eosyn e p h r i n e®) n a s a l s p ray 1 5 m L Lidoca i n e 4 % a q ueous 5 0 m L bottles Lidoca i n e 5% oi ntment (t u be) with to n g u e d e p ressors Lidoca i n e 2% g e l , Med C u p s a n d cotto n ba l l s for u se with J a c kson fo rceps Endoscopic l i g ht source replacement bu l b Po rtex fl exi b l e b ro n c h oscope swivel a d a pte rTM Ad u l t a n d Ped iatric Ma g i l l fo rce ps Metered Dose I n h a l e r i n - l i n e a d m i n i stration a d a pters I ntrave n o u s need l e/catheters fo r tra nscricoid i n se rt i o n ( 1 4 a n d 1 6 g a u g e x 2 of each) m u st be a s p i ration ca pa b l e with 3 mL syri n g e with 7.0- m m ID ETI c o n n ector E N K Oxyg e n F l ow Mod u l ator™ (Cook Critica l Ca re) 6.0-, 7.0-, a n d 8.0- m m I D E n d otro i TM tu bes-Ma l l i n c krodt K i n g LTS-D® of va r i o u s s izes (Am b u) Lig htwa n d L M A Fa strac h ® of va rious s izes Seco n d - g e n e ration EGOs of va rious s izes U n ive rsa l Cri cothyrotomy Kit™ (Cook Critica l Ca re) Retrog ra d e I ntu bati o n Kit™ (Coo k Critica l Ca re) Cook Ai rway Exc h a n g e Cath ete rsTM a n d A i ntree catheterTM (Coo k Critical Ca re) B ro n c h oscope Lig ht S o u rce S p a re Esc h m a n n Tra c h e a l Tu be I ntrod ucer 3 . 7 m m " Ped iatric" and 5.1 m m fl exi b l e b ro n c h oscopes

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Documentation of Difficult an d Failed Airway Manage ment Lorraine J. Foley, Michael F. Murphy a n d Orlando R. Hung

CAS E PRESENTATION

. . . 656

WHY SHOULD WE DOC U M ENT BOTH THE OCCU RRENCE A N D TH E MANAG EMENT O F A D I F F I C U LT OR FAI LE D AI RWAY? . . .

. . . 656

HAS THERE EVER BEEN A CO NCERTED EFFORT TO ESTA B L I S H A CE NTRA L " D I F F I C U LT AND FAI LE D AI RWAY REG I STRY"? . . . . . . . . . . . . . . . . . . . . . . . . . . . . 657 I S THERE ANY EVI DENCE THAT VERBAL ADVI CE, M E D I CAL RECORD DOC U M E NTATION, O R REG I STR I E S HAVE ANY E F F ECT IN REDUCING THE I N C I DENCE O F S U BSEQ U E NT ADVERSE AI RWAY MANAGEM ENT EVENTS? . . . . . . . . . 657 WHO S H O U L D U N DERTAKE TH E VERBAL ADVICE AND WRITIEN DOC U M E NTATION? WHEN S H O U L D THAT . 658 OCC U R?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . WHO S H O U L D BE ADVI SED OF THE EVENT? W H E RE S H O U L D WE DOC U M ENT T H E I N FO RMATI ON? . . . . . .

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WHAT S H O U L D WE DOC U M E NT? . . . . . . . . . . . . . . .

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S U MMARY .

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SELF-EVALUATIO N Q U ESTI O N S . . . . . . . . . . . . . . . . . .

66 1

CASE PRESENTATION An obese 39-year-old female is scheduled for a laparoscopic cholecystectomy under general anesthesia. She takes no meds and has no allergies. She is 5 '4" ( 1 6 1 em) , 220 lb ( 1 00 kg) , with a BMI 3 8 . 6 kg-m- 2 . She denies reflux. On physical exam, she has a Mallampati Class II airway, has 4 em mouth opening, and a good neck extension. Her hyomental distance is also less

than 5 em and her hypothyroid distance is about 3 em. She has no past surgical history except for a cesarean section under epi­ dural. Upon arrival at the operating room, standard monitors are placed on the patient. Following denitrogenation and induction of anesthesia with 200 mg of propofol, rocuronium (40 mg) is administered for muscle relaxation. Direct laryngoscopy is attempted with #3 Macintosh blade. Only a large epiglottis is seen with no improvement in the view following the applica­ tion of laryngeal pressure. A #3 Miller blade is then used to lift the epiglottis, but vocal cords are still not visible. An Eschmann Tracheal Introducer ("bougie") repeatedly goes into the esoph­ agus. Bag-mask-ventilation (BMV) remains adequate. Help and the difficult airway cart are summoned. A #3 Intubating Laryngeal Mask Airway (LMA-Fastrach) is placed, resulting in adequate ventilation. An attempt at blind intubation through the Intubating Laryngeal Mask Airway (ILMA) is unsuccessful. In a further attempt, a 7.0-mm ID endotracheal tube (ETT) is loaded onto the FAST (Foley fiberoptic airway stylet, Clarus Medical LLC, Minneapolis, MN) and placed through the ILMA. The ILMA is manipulated till vocal cords are visualized and the ETT is placed into trachea without difficulty. Correct ETT placement is confirmed by means of end-tidal C0 and 2 auscultation. The surgical procedure proceeds uneventfully. At the conclusion of the cholecystectomy, tracheal extubation is achieved with no difficulties when the patient is awake and alert. Appropriate monitoring and disposition of the patient are provided.

WHY SHOULD WE DOCU MENT BOTH T HE OCCU RRENCE A N D TH E MANAG EM E NT OF A D I F F I C U LT OR FAI LED AI RWAY? As indicated in earlier chapters (most notably Chapter 1 ) , a difficult or failed airway is not the same as a difficult or failed intubation, or a failed attempt at using an extraglottic device (EGD) or BMV It is critically important to be able to accurately

Doc u m e ntation of Diffi c u l t a n d Fa i l ed Ai rway M a nagement

describe, document, and communicate an adverse event related to airway management difficulty and/or failure. Failure to manage successfully an airway problem may cer­ tainly threaten patient safety and may also threaten the welfare of any airway practitioner. Attempts to improve outcomes in the management of a difficult/failed airway would require a system which records and reports this information to a widely disparate group of practitioners. The challenge is to create a system that conveys this information to this disparate group of practitioners dispersed in location and time. Practitioners are both legally and professionally vulnerable if they either fail to record or communicate critical information or fail to access and be aware of it. This underscores the importance of clear documentation of untoward airway events. Many difficult airways can be predicted after a routine care­ ful airway examination. Even so, unanticipated difficult and failed airways continue to occur. 1-3 One to 3% of patients undergoing general anesthesia present with unanticipated dif­ ficult airway/intubations when managed with conventional laryngoscopy. 4•5 A history of difficult airway has been shown to be an inde­ pendent risk factor for a patient presenting with second difficult airway.6·7 Documenting and communicating these incidents can therefore be crucial in preventing future airway disasters. Identifying patients who have had a previous "difficult airway" incident through accurate written and verbal documentation ensures that practitioners are not dependent on inaccurate ver­ bal histories to assess these at-risk patients. The American Society of Anesthesiology Closed Claims Analyses has consistently identified adverse airway outcomes as the largest class of injury.8•9 Of the events occurring in the 1 980s, 1 7% were due to difficult intubation. Cheney, 10 in an ASA newsletter published in June 1 997, compared the closed claims cases from the 1 970s, 1 980s, and 1 990s. The three most common adverse respiratory events causing death or brain dam­ age were inadequate ventilation, esophageal intubation, and difficult intubation. A marked reduction among these adverse events was noted over time. Interestingly, while inadequate ven­ tilation fell progressively (22% in 1 970s, 1 5% in 1 9 80s, and only 7% in 1 990s) and the incidence of death or brain damage decreased, difficult intubation as a cause of death or brain dam­ age increased from 5% in 1 970 to 1 2% in 1 990s. The number of claims in 1 990s due to difficult intubation was too small to reach statistical significance. The conclusion is interesting: while the decrease in inad­ equate ventilation and esophageal intubation may be due to the introduction of pulse oximetry and end-tidal C0 monitoring, 2 the approach to a difficult intubation will require a strategy with alternative airway techniques (Plans A, B, and C) . More importantly, the 4th National Audit Project (NAP4) , as well as other studies, have shown that repeated attempts at intubation causes swelling and bleeding, leading to a "cannot intubate, cannot oxygenate" situation, in addition to other complications.9• 11 • 1 2 In the Closed Claims review, Caplan et al. 8 showed that more than 50% of the difficult airway claims were in airways that were anticipated to be difficult. In the NAP4 study, 1 33 cases had major airway management complications. Of the

1 33 cases, half (66) were anticipated difficult airways. Of the 66 anticipated difficult airways, 41 of them had a history of airway management problems. A history of difficult airway management was found in the medical records of 32 of the 66 anticipated difficult airways. Only 1 4 of these 66 patients had received verbal or written communication in this regard. This serves to remind us that accurate and detailed communication of the patient's airway management is critically important. It is not just enough to say the patient has a difficult airway. 13 The "Difficult Airway Guidelines" of the American Society of Anesthesiologists ( 1 993, updated in 2003, and then in 20 1 3) repeatedly recommend documentation of airway management difficulty on the patient record AND in verbal discussion with the patient.

HAS THERE EVER B EEN A CONCERTED EFFORT TO ESTABLISH A CENTRAL "DI F F I C U LT A N D FAI LED AI RWAY REGI STRY"? Coincident with the development of these guidelines, an Anesthesia Advisory Council representing anesthesiologists, otolaryngologists, and experts in risk management joined together with the nonprofit MedicAlert Foundation to estab­ lish a National Difficult Airway/Intubation Registry. The major objective of this registry was to develop mechanisms for a uni­ form documentation and dissemination of critical information related to airway management difficulty and failure to protect patients. As a result, in 1 99 1 , the Anesthesia Advisory Council along with the MedicAlert Foundation established the category "Difficult Airway/Intubation." In 1 992, The World Federation of Societies of Anesthesia officially endorsed this initiative and in the same year, the American Academy of Otolaryngology­ Head and Neck surgeons followed suit. The Society for Airway Management (SAM) has endorsed the National MedicAl en. In 20 1 4, the SAM's MedicAlert Task Force updated a designated Difficult Airway Registry (www . medicalert. org/ everybody/difficult-airwayin tubation-registry) . Currently, the SAM is developing guidelines for dissemination of critical information on the difficult airway. Any health care provider who manages airways is able to uniformly document the patient's airway physical examination, the management of the difficult airway, and the patient's outcome, all via the inter­ net. A registration form can be downloaded, completed, and given to the patient. Once the patient is registered, this infor­ mation can be accessible worldwide.

IS THERE ANY EVI DENCE THAT VERBAL ADVICE, M E D ICAL RECORD DOCU M E NTATION, OR REG ISTRIES HAVE ANY EFFECT I N REDUCING TH E I NCI DENCE OF SU BSEQU ENT ADVE RSE AI RWAY MANAGEM ENT EVE NTS? Two small studies have shown a lower incidence of adverse out­ comes associated with a prior knowledge of difficult airway. The first employed The MedicAlert Foundation Registry Database. By February of 1 994, a total of 1 1 1 patients had been enrolled in the registry from over 30 states within the United States.

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Preliminary results suggested that knowledge of a prior difficult airway led to the use of fewer airway management techniques, and a lower incidence of adverse outcomes. 14 In the second study, a computerized In-Hospital Difficult Airway Registry had been developed at the Beth Israel Deaconess Medical Center in Boston, MA. 15 One hundred and twenty­ nine patients were entered into the registry during the period of April 1 995 and April 1 997. Of these patients, 3 1 returned at least once to the operating room. Uniform documentation of the prior airway management difficulty was available on the permanent medical record, reducing the need to rely on the patient's memory. There were no adverse outcomes related to airway management in their repeated visit to the operating room. Some locally based hospital systems have been able to track and warn future anesthesia practitioners by using their Anesthesia Information Management Systems (AIMS) . 16• 17 The operating room is not the only location in which a diffi­ cult airway may be encountered in a patient. Both the Peterson report9 and NAP41 1 identified a variety of locations outside the operating theater/room, ICU, hospital wards, and the emer­ gency department (ED) in their discussions. John Hopkins University developed a comprehensive difficult airway program which targeted three contributing factors that would increase complications related to airway management 1 1 : ( 1 ) inability t o access the written medical record; (2) lack of immediate access to equipment and supplies necessary to man­ age a difficult airway; and (3) lack of availability of trained personnel to help manage and secure the airway. The program incorporated electronically communicated patient information which could be accessed any time. It also mandated a green "difficult airway bracelet," immediate access to specific equip­ ment and the immediate availability of anesthesia and surgi­ cal staff. Following the implementation of this program, they showed that the number of emergency surgical airways were reduced from 1 992-1 995 6.5 ± 0 . 5 per year to 1 996-2006 2.2 ± 0.89 per year. 18 Practice guidelines have been promulgated by anesthe­ sia societies in North America and Europe, all recommend­ ing verbal communication with the patient and practitioners and written documentation of adverse airway management events. 1•19-2 1•22-24 Entering patients into a difficult airway regis­ try is also advisable.

WHO SHOULD U N D E RTAKE THE VERBAL ADVICE AND WRITTEN DOCU M E NTATION? WHEN SHOULD THAT OCC U R? If feasible, patients should be verbally advised in jargon-free language about the event by the practitioners themselves when the patient is alert and oriented in the post-anesthesia care unit, recognizing that this may not always be possible. More impor­ tantly, patients should be able to confirm their understanding of the gravity of the situation and its details are understood. Because of the residual effects of medications, the complexity of the event and the vagaries of memory, a written narrative must also be given to the patients to take with them so they can show to subsequent practitioners if possible.

WHO SHOULD BE ADVI SED OF TH E EVENT? WHERE SHOULD WE DOC U M ENT TH E I N FORMATION? Besides the patient, the following should be briefed either ver­ bally or in written form: •

•

•

Patient family members if available Primary care provider notified in writing Depending on the context, the surgeon, the intensivist, or the admitting physician, should be told at time after the intubation.

A form letter ought to be sent with the patient delineat­ ing the precise issues encountered, the methods employed to circumvent the airway difficulties, and advice regarding future management strategies. The practitioner's identifYing data and contact information should be included. Similar documenta­ tion should be entered in the permanent medical record.

WHAT S H O U L D WE DOCU M E NT? The documentation of a relevant airway management event ought to independently address the four basic airway techniques identified in Chapter 1 if they were employed. For example: was the BMV difficult? Was the use of the EGD difficult? Was direct or indirect (video) laryngoscopy and intubation difficult? Was laryngoscopy performed with or without laryngeal manip­ ulation? Were other airway adjuncts used? Were other intuba­ tion techniques employed? Was cricothyrotomy necessary as a rescue technique? In addition, during laryngoscopy, Laryngeal View Grading system as proposed by Cormack and Lehane (C/L) 2 5 or Levitan's percentage of glottic opening (POG0) 26 should also be reported. While there is no general agreement regarding the infor­ mation that should be recorded in the patient's chart, the authors believe that the following information ought to be in the note: Date of operation: Type of operation: Hospital and medical record number Physical examination that may contribute to the problem: height, weight, BMI, Mallampati classification, mouth opening, receding chin, range of motion of the cervical spine, etc. Medical history that may contribute to the difficult air­ way: rheumatoid arthritis, diabetes, obesity, obstructive sleep apnea, radiation to the head and neck, etc. Mask-ventilation: easy, difficult, or impossible Oral or nasal airway size Type and size of laryngoscope or video-laryngoscope used Number of attempts at laryngoscopy and intubation, including laryngoscopic view Alternative airway techniques attempted: if successful or not Any recommendations

Doc u m e ntation of Diffi c u l t a n d Fa i l ed Ai rway M a nagement

The example for this patient management documentation would be as follows: Date of operation: 4/ 1 2/05 Type of operation: Laparoscopic Cholecystectomy Winchester Hospital, Winchester MA, Medical Record # 1 23-45-67 PE: 5 '4" ( 1 6 1 em) , 220 lb ( 1 00 kg) , with a BMI 3 8 . 6 kg·m- 2 , otherwise healthy normal anatomy Easy mask-ventilation Attempt 1 -Macintosh 3; grade 3 (C/L) laryngoscopic view, no change with BURP, unsuccessful Attempt 2-Miller 3; grade 3 (C/L) laryngoscopic view, Eschmann Introducer ("bougie") passed, esophageal intubation Attempt 3-ILMA #3 good ventilation, blind ETT passed, unsuccessful Attempt 4-ILMA #3, ETT with Foley fiberoptic airway srylet successful Recommendation for future management: Depending on the circumstances, awake intubation provides the widest margin of safety to secure the airway for future elective procedures.

S U M MARY Following the successful management of a difficult or failed air­ way, the standard of care requires at a minimum that the prac­ titioner advises the patient verbally and in writing and places in the permanent medical record the facts as to what transpired, and further records the devices and techniques which failed and succeeded, and recommendations as to future airway manage­ ment strategies. A suggested sample form letter to be sent with this patient:

Dear Patient, As we discussed during our postoperative visit, you under­ went general anesthesia (completely asleep for surgery) . This required a breathing tube to be placed in your windpipe to deliver oxygen to your lungs, heart, brain, and other vital organs. Under anesthesia, it was difficult to place the breath­ ing tube in your windpipe. This is referred to as a "Difficult Airway."

Now that we know that you have a "Difficult Airway," it is important that you do the following to help protect yourself. 1 . Tell your primary care physician or family doctor that you have a "Difficult Airway." 2. Tell your family and others of your choosing that you have a "Difficult Airway" in case they need to provide this informa­ tion on your behalf. 3. For any future surgical procedure, it is important that you should inform your anesthesiologist that you have a "Difficult Airway." Show your anesthesiologist a copy of the attached form that contains all the medical details needed to manage your difficult airway. 4. You are strongly advised to enroll in the MedicAlert Foundation's Registry for Difficult Airway/Intubation. a. Fill out the attached MedicAlert Foundation application for enrollment and send a copy of the "Difficult Airway'' information form and membership fee along with it. b. After you enroll, you will receive an ID number, wal­ let card with the MedicAlert Foundation toll-free phone number, and a custom engraved "Difficult Airway/!" metal emblem on a necklace or bracelet. c. Your "DIFFICULT AIRWAY" information will be in the Registry at the MedicAlert Foundation, which has safe­ guards for patient confidentiality. d. In an emergency or ifyou have surgery, your "DIFFICULT AIRWAY" information can be accessed by your health care provider or any provider 24 hours a day, 7 days a week, at no charge. I have informed you of your DIFFICULT AIRWAY because it is extremely important that you are aware of the difficulties in placing a breathing tube. Please keep this letter in a safe place for future reference. I cannot emphasize enough how important it is for you to wear a MedicAlert emblem bracelet or necklace. It could be lifesav­ ing! If you are unable to afford the enrollment fee, please let me know and I can write a letter for a waiver of the fee. Please con­ tact me if you have any questions or desire further information. Sincerely, Staff Physician Anesthesiologist Hospital Address Phone:

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Practical Consid e rat i o n s in Ai rway M a n a g e m e n t DIFFICULT AIRWAY MEDICAL INFORMATION FORM {apply patient sticker)

was found to have a "DIFFICULT AIRWAY" on

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MR#

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Mask Ventilation: __

Easy

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Difficult Intubation

Telephone#

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Difficult

!

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!

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__

at

_ _ _ _ _ _ _ _ _ __

-------

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Impossible

Difficult Laryngoscopy

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Failed Intubation

Xxx

Physical Exam: Reason for Difficulty

Height:

Weight:

Mouth Opening: Teeth:

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prominent

Thyromental Distance:

Mallampati Class {I-IV) :

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em

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Neck Extension:

edentulous

Large Tongue: