Linz's Comprehensive Respiratory Diseases [1 ed.] 2018058170, 9781449652715, 1449652719, 9781284102932, 9781449652005, 076377653X

Table of contents :
LINZ’S Comprehensive Respiratory Diseases
Title Page
Dedication
Copyright
Brief Contents
Contents
Preface
How to Use this Book
About the Author
Acknowledgments
Contributors
Reviewers
Chapter 1 Cardiopulmonary Assessment
Introduction
Taking a History
Vital Signs
Essential Elements of a Pulmonary Examination
Essential Elements of the Cardiac Examination
Neurologic Assessment
Chapter 2 Diagnostic Testing and Monitoring
Introduction
Pulmonary Diagnostic Tests
Noninvasive Monitoring
Diagnostic Laboratory Tests
Diagnostic Imaging
Cardiac Diagnostic Tests and Monitoring
Chapter 3 Respiratory Failure
Introduction
Acute Hypoxemic Respiratory Failure
Acute Hypercapnic Respiratory Failure
Differentiating Hypoxemic and Hypercapnic Respiratory Failure
Chronic Respiratory Failure
Acute-on-Chronic Respiratory Failure
Prognosis for Respiratory Failure
Chapter 4 Neuromuscular Diseases
Introduction
Central Nervous System Disorders
Spinal Cord Disorders
Peripheral Motor Nerve Disorder
Neuromuscular Junction Disorders
Muscular Disorders
Prognosis for Neuromuscular Diseases
Chapter 5 Disorders of the Chest Wall and Pleura
Introduction
Disorders of the Chest Wall
Disorders of the Pleura
Chapter 6 Upper Airway Obstruction Disorders
Introduction
Definition/Diagnosis
Clinical Signs and Symptoms
Etiology
Epidemiology
Pathology/Pathophysiology
Diagnostic Testing
Fixed UAO
Variable Extrathoracic UAO
Variable Intrathoracic UAO
Chapter 7 Sleep-Related Breathing Disorders
Introduction
Definitions
Obstructive Sleep Apnea
CSA Syndromes
Sleep-Related Hypoventilation Disorders
Chapter 8 Asthma
Introduction
Definition/Diagnosis
Clinical Signs and Symptoms
Etiology
Epidemiology
Pathology/Pathophysiology
Risk Factors
Complications
Diagnostic Testing
Treatment and Management
Prognosis
Chapter 9 Chronic Obstructive Pulmonary Disease
Introduction
Definition/Diagnosis
Clinical Signs and Symptoms
Etiology
Epidemiology
Pathology/Pathophysiology
Risk Factors
Complications
Diagnostic Testing
Treatment and Management
Prognosis
Chapter 10 Cystic Fibrosis and Bronchiectasis
Cystic Fibrosis
Bronchiectasis
Chapter 11 Burns and Inhalational Injuries
Introduction
Definition/Diagnosis
Clinical Signs and Symptoms
Etiology
Epidemiology
Pathology/Pathophysiology
Risk Factors
Complications
Diagnostic Testing
Treatment and Management
Prognosis
Chapter 12 Lung Carcinoma
Introduction
Non-Small Cell Lung Carcinoma
Small Cell Lung Carcinoma
Chapter 13 Pneumonia
Introduction
Pneumonia Classification by Causative Microorganism
Pneumonia Classification by Anatomic Location
Pneumonia Classification by Origin of Development
Chapter 14 Cardiac Arrhythmias
Introduction
Cardiac Arrest Arrhythmias
Non-arrest Arrhythmias
Chapter 15 Heart Failure
Heart Failure
The Cardiomyopathies
Valvular Heart Diseases
Congenital Heart Disease
Pericardial Diseases
Left Ventricular Hypertrophy
Chapter 16 Ischemic Heart Disease
Introduction
Definition and Diagnosis
Etiology
Epidemiology
Pathology/Pathophysiology
Clinical Manifestations
Noninvasive Diagnostic Testing
Diagnostic Testing—Invasive
Treatment and Management
Coronary Artery Bypass Grafting
Cardiac Rehabilitation
Risk Factors
Prevention
Complications
Prognosis
Chapter 17 Pulmonary Vascular Diseases
Introduction
Pulmonary Embolism
Pulmonary Artery Hypertension
Chapter 18 Shock
Introduction
Cardiogenic Shock
Hypovolemic Shock
Anaphylactic Shock
Septic Shock
Neurogenic Shock
Chapter 19 Acute Respiratory Distress Syndrome
Introduction
Definition/Diagnosis
Risk Factors for ARDS
Pathology and Pathophysiology
Clinical Manifestations
Treatment and Management
Prone Positioning
Extracorporeal Life Support
Pharmacologic Treatment
Chapter 20 Drowning Injury
Introduction
Definition/Diagnosis
The Drowning Process
Clinical Signs and Symptoms
Etiology
Epidemiology
Pathophysiology
Risk Factors
Complications Associated with Drowning
Diagnostic Testing
Treatment and Management
Prognosis
Chapter 21 Interstitial Lung Disease
Introduction
Definition/Diagnosis
Clinical Signs and Symptoms
Etiology
Epidemiology
Pathogenesis
Risk Factors
Complications
Diagnostic Testing
Treatment and Management
Prognosis
Chapter 22 Postoperative Pulmonary Complications
Introduction
Pulmonary Complication Risk Factors
Preoperative Assessment for Pulmonary Risk
Common PPCs
Strategies to Reduce PPCs
Chapter 23 Pulmonary Tuberculosis
Introduction
Definition/Diagnosis
Clinical Signs and Symptoms
Etiology
Epidemiology
Pathology/Pathophysiology
Risk Factors
Complications
Diagnostic Testing
Treatment and Management
Prognosis
Chapter 24 Neonatal and Pediatric Pulmonary Disorders
Introduction
Neonatal
Pediatrics
Chapter 25 Lung Transplantation
Introduction
The Transplantation System
Candidate (Recipient) Selection
Donor Selection
Lung Transplant Procedures
Posttransplant Management
Common Complications of Lung Transplantation
Lung Transplantation Prognosis
Chapter 26 Palliative of the Respiratory Patient
Introduction
Barriers to Effective Palliative Care
Palliative Management Concerns
Management of Common Symptoms
Palliative Care in Chronic Progressive Lung Disorders
Advanced Directives
Palliative Care in Advanced-Stage Lung Cancer
The ICU and Palliative Care
Withdrawing Life Support
Hospice and End-of-Life Care
Palliative Homecare
Hospice Homecare
Palliative Sedation Therapy
Bereavement Counseling
Chapter 27 Disease Management
Introduction
Healthcare System
Etiology of Chronic Disease
Disease Management
The Chronic Care Model
Disease Management Programs
Self-Management
Evaluation of the DM Process
Glossary
Index

Citation preview

LINZ’S

Comprehensive

Respiratory Diseases Sindee Kalminson Karpel Anthony Linz

ACCESS CODE INSIDE

World Headquarters Jones & Bartlett Learning 5 Wall Street Burlington, MA 01803 978-443-5000 [email protected] www.jblearning.com Jones & Bartlett Learning books and products are available through most bookstores and online booksellers. To contact Jones & Bartlett Learning directly, call 800-832-0034, fax 978-443-8000, or visit our website, www.jblearning.com. Substantial discounts on bulk quantities of Jones & Bartlett Learning publications are available to corporations, professional associations, and other qualified organizations. For details and specific discount information, contact the special sales department at Jones & Bartlett Learning via the above contact information or send an email to [email protected]. Copyright © 2020 by Jones & Bartlett Learning, LLC, an Ascend Learning Company All rights reserved. No part of the material protected by this copyright may be reproduced or utilized in any form, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without written permission from the copyright owner. The content, statements, views, and opinions herein are the sole expression of the respective authors and not that of Jones & Bartlett Learning, LLC. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not constitute or imply its endorsement or recommendation by Jones & Bartlett Learning, LLC and such reference shall not be used for advertising or product endorsement purposes. All trademarks displayed are the trademarks of the parties noted herein. Linz’s Comprehensive Respiratory Diseases is an independent publication and has not been authorized, sponsored, or otherwise approved by the owners of the trademarks or service marks referenced in this product. There may be images in this book that feature models; these models do not necessarily endorse, represent, or participate in the activities represented in the images. Any screenshots in this product are for educational and instructive purposes only. Any individuals and scenarios featured in the case studies throughout this product may be real or fictitious, but are used for instructional purposes only. 77653-4 Production Credits VP, Product Management: Amanda Martin Director of Product Management: Cathy L. Esperti Product Specialist: Rachael Souza Project Specialist: Daniel Stone Senior Production Editor, Navigate: Leah Corrigan Marketing Manager: Michael Sullivan VP, Manufacturing and Inventory Control: Therese Connell

Composition and Project Management: S4Carlisle Publishing Services Cover Design: Scott Moden Rights & Media Specialist: Maria Leon Maimone Media Development Editor: Troy Liston Cover Image (Title Page, Chapter Opener): © TairA/Shutterstock Printing and Binding: LSC Communications Cover Printing: LSC Communications

Library of Congress Cataloging-in-Publication Data Names: Karpel, Sindee K., author. Title: Linz’s comprehensive respiratory diseases / Sindee Karpel. Other titles: Comprehensive respiratory diseases Description: Burlington, Massachusetts : Jones & Bartlett Learning, [2020] | Includes bibliographical references and index. Identifiers: LCCN 2018058170 | ISBN 9781449652715 (pbk. : alk. paper) Subjects: | MESH: Respiratory Tract Diseases--diagnosis | Respiratory Tract Diseases--therapy | Respiratory Therapy--methods | Case Reports Classification: LCC RC731 | NLM WF 141 | DDC 616.2--dc23 LC record available at https://lccn.loc.gov/2018058170 6048 Printed in the United States of America 23 22 21 20 19   9 8 7 6 5 4 3 2 1

To my husband, Larry, for all his love and support. To my children, Brad and Jordan, for challenging me daily. In memory of my parents, Herman and Bertha Kalminson.

Chapter 1

Cardiopulmonary Assessment  1

Chapter 2

Diagnostic Testing and Monitoring  31

Chapter 3

Respiratory Failure  67

Chapter 4

Neuromuscular Diseases  89

Chapter 5

Disorders of the Chest Wall and Pleura  109

Chapter 6

Upper Airway Obstruction Disorders  145

Chapter 7

Sleep-Related Breathing Disorders  169

Chapter 8 Asthma 203 Chapter 9

Chronic Obstructive Pulmonary Disease  227

Chapter 10 Cystic Fibrosis and Bronchiectasis  245 Chapter 11 Burns and Inhalational Injuries  263 Chapter 12 Lung Carcinoma  293 Chapter 13 Pneumonia  315 Chapter 14 Cardiac Arrhythmias  355 Chapter 15 Heart Failure  391 Chapter 16 Ischemic Heart Disease  439 Chapter 17 Pulmonary Vascular Diseases  463 Chapter 18 Shock  495 Chapter 19 Acute Respiratory Distress Syndrome  523 Chapter 20 Drowning Injury  541 Chapter 21 Interstitial Lung Disease  569 Chapter 22 Postoperative Pulmonary Complications  591 Chapter 23 Pulmonary Tuberculosis  613

iv

© TairA/Shutterstock

Brief Contents

Brief Contents Chapter 24 Neonatal and Pediatric Pulmonary Disorders  631 Chapter 25 Lung Transplantation  671 Chapter 26 Palliative of the Respiratory Patient  697 Chapter 27 Disease Management  723 Glossary  739 Index  761

v

Preface  ix How to Use this Book  x About the Author  xii Acknowledgments  xiii Contributors  xiv Reviewers  xv Chapter 1 Cardiopulmonary Assessment  1

Chapter 5 Disorders of the Chest Wall and Pleura  109 Introduction 110 Disorders of the Chest Wall 111 Disorders of the Pleura 129

Chapter 6 Upper Airway Obstruction Disorders  145

Introduction 2

Introduction 146

Taking a History 2

Definition/Diagnosis 146

Vital Signs  6

Clinical Signs and Symptoms 148

Essential Elements of a Pulmonary Examination  11

Etiology 148

Essential Elements of the Cardiac Examination 21

Pathology/Pathophysiology 149

Neurologic Assessment 23

Chapter 2 Diagnostic Testing and Monitoring  31 Introduction 32 Pulmonary Diagnostic Tests 33 Noninvasive Monitoring 36 Diagnostic Laboratory Tests 44

Epidemiology 148 Diagnostic Testing 152 Fixed UAO 153 Variable Extrathoracic UAO 157 Variable Intrathoracic UAO 162

Chapter 7 Sleep-Related Breathing Disorders  169

Diagnostic Imaging 50

Introduction 170

Cardiac Diagnostic Tests and Monitoring 56

Definitions 175

Chapter 3 Respiratory Failure  67

Obstructive Sleep Apnea 176

Introduction 68

CSA Syndromes 189

Acute Hypoxemic Respiratory Failure 70

Sleep-Related Hypoventilation Disorders 194

Acute Hypercapnic Respiratory Failure 77 Differentiating Hypoxemic and Hypercapnic Respiratory Failure 81 Chronic Respiratory Failure 82 Acute-on-Chronic Respiratory Failure 83 Prognosis for Respiratory Failure 86

Chapter 4 Neuromuscular Diseases  89 Introduction 90 Central Nervous System Disorders 94 Spinal Cord Disorders 96 Peripheral Motor Nerve Disorder 99 Neuromuscular Junction Disorders 100 Muscular Disorders 103 Prognosis for Neuromuscular Diseases 105

vi

© TairA/Shutterstock

Contents

Chapter 8 Asthma  203 Introduction 204 Definition/Diagnosis 205 Clinical Signs and Symptoms 206 Etiology 208 Epidemiology 208 Pathology/Pathophysiology 209 Risk Factors 213 Complications 213 Diagnostic Testing 214 Treatment and Management 218 Prognosis 222

Contents Chapter 9 Chronic Obstructive Pulmonary Disease  227

Chapter 15 Heart Failure  391 Heart Failure  392

Introduction 228

The Cardiomyopathies  404

Definition/Diagnosis 229

Valvular Heart Diseases  412

Clinical Signs and Symptoms 230

Congenital Heart Disease  424

Etiology 230

Pericardial Diseases  427

Epidemiology 231

Left Ventricular Hypertrophy  431

Pathology/Pathophysiology 232 Risk Factors 233 Complications 234 Diagnostic Testing 234 Treatment and Management 238 Prognosis 241

Chapter 10 Cystic Fibrosis and Bronchiectasis  245

Chapter 16 Ischemic Heart Disease  439 Introduction  440 Definition and Diagnosis  441 Etiology  441 Epidemiology  442 Pathology/Pathophysiology  442 Clinical Manifestations  444 Noninvasive Diagnostic Testing  444

Cystic Fibrosis 246

Diagnostic Testing—Invasive  449

Bronchiectasis 254

Treatment and Management  452

Chapter 11 Burns and Inhalational Injuries  263 Introduction 264 Definition/Diagnosis 264 Clinical Signs and Symptoms 266 Etiology  271 Epidemiology  271 Pathology/Pathophysiology  273

Coronary Artery Bypass Grafting  455 Cardiac Rehabilitation  455 Risk Factors  456 Prevention  456 Complications  457 Prognosis  458

Chapter 17 Pulmonary Vascular Diseases  463

Risk Factors  276

Introduction  464

Complications  277

Pulmonary Embolism  466

Diagnostic Testing  279

Pulmonary Artery Hypertension  478

Treatment and Management  280 Prognosis  286

Chapter 12 Lung Carcinoma  293

Chapter 18 Shock  495 Introduction  497 Cardiogenic Shock  497

Introduction  294

Hypovolemic Shock  504

Non-Small Cell Lung Carcinoma  295

Anaphylactic Shock  508

Small Cell Lung Carcinoma  306

Septic Shock  512

Chapter 13 Pneumonia  315 Introduction  316 Pneumonia Classification by Causative Microorganism  316

Neurogenic Shock  518

Chapter 19 Acute Respiratory Distress Syndrome  523 Introduction  524

Pneumonia Classification by Anatomic Location  338

Definition/Diagnosis  524

Pneumonia Classification by Origin of Development  341

Pathology and Pathophysiology  525

Chapter 14 Cardiac Arrhythmias  355

Risk Factors for ARDS  524 Clinical Manifestations  526 Treatment and Management  527

Introduction  357

Prone Positioning  531

Cardiac Arrest Arrhythmias  358

Extracorporeal Life Support  533

Non-arrest Arrhythmias  368

Pharmacologic Treatment  534

vii

viii

Contents Chapter 20 Drowning Injury  541 Introduction  542

Chapter 24 Neonatal and Pediatric Pulmonary Disorders  631

Definition/Diagnosis  543

Introduction  632

The Drowning Process  543

Neonatal  632

Clinical Signs and Symptoms  544

Pediatrics  656

Etiology  546 Epidemiology  547 Pathophysiology  548 Risk Factors  554 Complications Associated with  Drowning  556 Diagnostic Testing  556 Treatment and Management  557 Prognosis  563

Chapter 21 Interstitial Lung Disease  569 Introduction  570 Definition/Diagnosis  571 Clinical Signs and Symptoms  571 Etiology  572 Epidemiology  574 Pathogenesis  574 Risk Factors  578

Chapter 25 Lung Transplantation  671 Introduction  672 The Transplantation System  673 Candidate (Recipient) Selection  674 Donor Selection  678 Lung Transplant Procedures  679 Posttransplant Management  680 Common Complications of Lung Transplantation  683 Lung Transplantation Prognosis  691

Chapter 26 Palliative of the Respiratory Patient  697 Introduction 698 Barriers to Effective Palliative Care 700 Palliative Management Concerns 702 Management of Common Symptoms 703

Complications  578

Palliative Care in Chronic Progressive Lung Disorders 709

Diagnostic Testing  579

Advanced Directives 710

Treatment and Management  585

Palliative Care in Advanced-Stage Lung Cancer 712

Prognosis  587

Chapter 22 Postoperative Pulmonary Complications  591 Introduction  592 Pulmonary Complication Risk Factors  593 Preoperative Assessment for Pulmonary Risk  597 Common PPCs  598 Strategies to Reduce PPCs  604

Chapter 23 Pulmonary Tuberculosis  613 Introduction  614 Definition/Diagnosis  615 Clinical Signs and Symptoms  615 Etiology  616 Epidemiology  616 Pathology/Pathophysiology  617 Risk Factors  619 Complications  620 Diagnostic Testing  620 Treatment and Management  624 Prognosis  626

The ICU and Palliative Care 713 Withdrawing Life Support 713 Hospice and End-of-Life Care 714 Palliative Homecare 715 Hospice Homecare 716 Palliative Sedation Therapy 716 Bereavement Counseling 717

Chapter 27 Disease Management  723 Introduction  724 Healthcare System  724 Etiology of Chronic Disease  725 Disease Management  726 The Chronic Care Model  728 Disease Management Programs  729 Self-Management  732 Evaluation of the DM Process  735

Glossary 739 Index 761

© TairA/Shutterstock

Preface T

he profession of respiratory care is continuously evolving. The respiratory therapist (RT) of today is quite different from the RT of 38 years ago, when I started out in the profession. Back then RTs did little more than deliver oxygen and turn some knobs on mechanical ventilators. We are now called upon to utilize clinical critical thinking to share in the development, assessment, and revision of patient care plans, protocol administration, patient education, and disease management. RTs are becoming more involved in home care, outpatient care, private office practice, end-of-life and palliative care, and smoking cessation programs, as well as case managers for pulmonary disease patients. With these expanded roles, RTs rely heavily on their knowledge of pulmonary diseases and with this knowledge are expected to make and defend their clinical judgments. The goal of this text is to assist respiratory therapy students in gaining the pulmonary disease knowledge base necessary to pass the National Board for Respiratory Care’s (NBRC) Registered Respiratory Therapist (RRT) credentialing exams and function as competent, confident respiratory therapists.

Audience The target audience for this book is students enrolled in respiratory care programs. Others who may find the content germane to their practice include respiratory therapists, physician assistants, nurses, nurse practitioners, and medical school students.

Organization This book is designed to provide a comprehensive overview of the pulmonary and cardiac disorders that are covered on the NBRC board exams and most frequently

require an RT’s care in clinical settings. Each chapter includes the following elements: ■■ ■■ ■■

■■ ■■ ■■

Chapter objectives and key terms to understand the chapter learning objectives. A case study is then presented to introduce the topic. The reader is then given the most up-todate information on the diagnosis, etiology, epidemiology, pathophysiology, diagnostic testing, treatment, and management of each disorder. Knowledge check questions are included in every chapter. Illustrations, tables, and figures support concepts in each chapter. Student learning is enriched with a chapter summary, key points, and NBRC-type questions at the conclusion of each chapter.

Instructor Resources Qualified instructors will receive a full suite of instructor resources, including the following: ■■ ■■

■■ ■■

A comprehensive chapter-by-chapter PowerPoint deck A Test Bank containing questions on a chapter-by-chapter basis, as well as a Midterm and a Final Answers to the Knowledge Check questions and the end-of-chapter review questions Additional Case Studies with questions and answers

Sindee Kalminson Karpel, MPA, RRT, AE-C

ix

Chapter Features ■■

■■

■■

Each chapter of the book begins with a list of Chapter Objectives to help you focus on the most important concepts in that chapter. Each chapter contains Tables that highlight important information, such as Table 3.5 Determining Optimal PEEP.

© TairA/Shutterstock

How to Use this Book This text is highly illustrated with diagrams and photos demonstrating a variety of concepts.

Trachea (extrathoracic)

Trachea (intrathoracic)

Thorax

TABLE 3-5 Determining Optimal PEEP Method

Use

Explanation

Static compliance method

For volume control ventilation

Keep VT setting constant, measure and record exhaled VT and Pplateau or CSTAT at different PEEP settings. The optimal PEEP setting produces the highest CSTAT.

Equal pressure method

For pressure control ventilation

Keep the PIP–PEEP (∆P) constant (15–25 cm H2O) while making changes to the PEEP. (This means changes to the PIP to keep the ∆P constant.) 82 Record the exhaled VT at each change. The PEEP setting that gives the largest VT represents the optimal PEEP.

Tissue oxygen delivery

Pflex or low inflection point

For patients with Pulmonary Artery Catheters

For ventilator graphics

O2 Delivery = Cardiac Output × Cao2. At each change of PEEP, use the pulmonary artery catheter to measure the cardiac output while drawing an ABG. Calculate the Cao2, and then determine the O2 delivery. Optimal PEEP produces the highest O2 delivery. Examine the pressure–volume curve. The intersection point between the slopes of the highcompliance segment and the lowcompliance segment is the low inflection point or the Pflex point. The optimal PEEP is 2–3 cm H2O above the Pflex point.

FIGURE 6-5   Intrathoracic and extrathoracic airways. ■■ Each 3 chapter includes aFailure Case Study to put the CHAPTER Respiratory concepts discussed within the chapter in real-life scenarios.

Chronic Respiratory Failure

Case Study 3 A 39-year-old man comes to the hospital for his preoperative evaluation prior to gastrointestinal bypass surgery for his obesity. He weighs 465 lb and is 5 foot 11 inches tall (body mass index 194 kg/m2). He has been morbidly obese for more than 20 years. A baseline ABG was drawn on room air. The results are pH 7.46, PaCO2 72 torr, PaO2 53 torr, SaO2 81%, HCO−3 28 mEq/L (he is the patient mentioned in Box 3-5). This is a fully compensated respiratory acidosis with moderate hypoxemia. As shown in Box 3-6, the hypoxemia is due to the hypoventilation (hypercapnia).

Definition x

Central nervo

Chronic respiratory failure (CRF) typically involves inappropriate levels of minute ventilation or an increase in dead space. Manifestations of CRF, also called chronic ventilatory failure, in contrast to those of acute

Decrease to brea

FIGURE 3-7

Redrawn from Han Medicine. Lange M

dystrophies Chest wall racoplasty. tracheal ste

Assessme

CRF is a pr dispose a p

ing cause of mortality in many neuromuscular diseases that weaken the respiratory muscles, rendering them incapable of sustaining normal breathing. The incidence of respiratory failure does appear to increase significantly for each decade of life until 85 years of age ■■ aKnowledge Questions appear throughout with particularlyCheck high incidence observed in patients the chapters to help students test what they have over the age of 65. learned.

KNOWLEDGE CHECK QUESTIONS 1. Respiratory failure due to increased ventilatory demand may be caused by: a. sepsis b. obesity c. neuromuscular disease d. upper airway obstruction 2. True or False: Metabolic acidosis can lead to respiratory failure due to a decrease in ventilatory demand.

using either Pa2 or Sa2 (Box 3-2). Hypoxemia is a very dangerous situation because it 106 can CHAPTER 4 Neuromuscular Diseases lead to tissue hypoxia and death. the HowThtoe organs Use thisofBook body that are at greatest risk due hypoxemia are the 5. Theto differential diagnosis of neuromuscular KNOWLEDGE CHECK QUESTIONS disorders depends on the muscle and nerve CNS and the heart. Tissue hypoxia causes cell byof groups that are affected, age atinjury onset, the rate 1. True or False: NIV does not normalize the life progression, genetic predisposition, blood tests, ■ ■ Each chapter concludes with aexamination, summary, Key expectancy of a patient with neuromuscular adenosine triphosphate depletion, intracellular acidosis, physical and possibly a biopsy. disorders. The Tensilon as test, using edrophonium, Points and Chapter Questions a free review ofhelps the the build-up radicals, diagnose MG.and A positive test demonstrates 2. True or False: Quality of of lifemetabolic for patients with byproducts improvement in muscle strength following its neuromuscular disorders may improve with the important concepts within the chapter. administration. SFEMG is a more andusethe induction of inflammation. TheHowever, assessment of an MIE. sensitive test for MG. 6. Noninvasive mechanical than ventilationjust is becomof adequate oxygenation depends on more a ing more commonly used with neuromuscular patients. Chapter Summary simple evaluation of Pa2 and7.Sao . Tissue oxygenation 2 Chronic respiratory failure due to a neuromuscular Overall, patients who suffer from a neuromuscular disorder of may cause to liberate the patient disease process may showfour differentfactors: signs and symp- the ability depends on thefailure respiratory from noninvasive mechanical ventilation. Invasive toms upon presentation to the physician’s office or the mechanical ventilation is an option to be considacute care facility. It is always important to start with system to bring in oxygen (ventilate), the ability to difered at this point. obtaining a patient history and physical examination, 8. Therapies available for the treatment of neuromusif appropriate, then begin with more in-depth assessfuse the oxygen across the alveolar-capillary membrane, cular disorders may improve the quality of life for ment and testing, if needed. In some of these cases, the many of these patients. The MIE (Cough-Assist®) is end outcome of the diseaseof process is terminal, while the presence enough hemoglobin in the blood to one such therapy. in others it is resolvable, and the patient may maintain 9. Treatment for chronic neuromuscular diseases rea relatively normal lifestyle after the event. It will all carry the oxygen to the tissues, anda team theapproach ability of the quires with numerous healthcare begin with determining the correct disease process and practitioners and family members. then being able to provide the appropriate treatment for cardiovascular system to bring oxygen to thedisorders tissues. 10. the The prognosis for neuromuscular dethese patients. pends on the extent of the cardiopulmonary Many tests are available for the physicians’ offices involvement. include perfusion Other factors involved in oxygenation and at the hospitals to identify the type of neuromuscular disorder and its severity. Hopefully, this will occur as of theas possible, tissues, extraction of oxygen by the tissues, and promptly to expedite the treatment. In some Chapter Questions cases, the patient may remain in the hospital setting for 1. Th e ________________ nerve has no effect on the utilization of the by the cells. an extended period. Treatment mayoxygen involve noninvasive upper airways. and invasive life support depending on the severity of the disease process and the patient’s overall health.

Key Points Causes

1. Neuromuscular disorders consist of a variety of process that affects voluntary muscles of the body.

Acute Hypoxemic Respiratory Failure Definition Hypoxemic respiratory failure is also known as Type I respiratory failure, lung failure, or oxygenation failure. Hypoxemia is a decreased Pa2 in the blood, below the normal range.2 Hypoxemic respiratory failure can be either acute (minutes to hours) or chronic (several days or longer). The American Association for Respiratory Care (AARC) Clinical Practice Guideline for Oxygen Therapy for Adults in the Acute Care Facility3 defines a Pa2 of less than 60 torr or an Sa2 of less than 90% in while breathing room air as hypoxemia. Additionally, a

a. glossopharyngeal b. vagus c. lumbar T8 d. spinal accessory 2. Receptors for ____________ and _______________ drive the response of the brain to breathe. a. Pa2; HCO−3 b. Pa2; Pa2 c. Sa2; Hb d. HCO−3 ; Pa2 3. A/An ___________ is not a useful test to assess a patient with a questionable neuromuscular disease process. a. arterial blood gas analysis b. pulmonary function testing c. urine output d. chest radiograph 4. ________________ is a central nervous system disorder. a. Amyotrophic lateral sclerosis (ALS) b. poliomyelitis c. botulism d. Guillain–Barre syndrome

ThTheeseunderlying pathophysiologic causes of acute hyinclude central nervous system disorders, drug overdose, spinal cord disorders, peripheral motor nerve disorder, neuromuscular junction dis- include problems with varipoxemic respiratory failure orders, and muscular disorders. 2. Thisprocesses chapter covered poliomyelitis and PPS (cenous that bring oxygen into the lungs, across tral nervous system disorders); ALS and spinal cord injury (spinal cord disorders); Guillain–Barre thesyndrome alveolar-capillary membrane, and to the cells of (peripheral motor nerve disorder); MG, and tetanus (neuromuscular junction disthebotulism, body. Th ese causes include ventilation–perfusion orders); and DMD (muscular disorders). 3. The etiologies of neuromuscular disorders include mismatch, alveolar hypoventilation, decreased fraction genetic mutations, viral infections, bacterial inautoimmune diseases, and metabolic of fections, inspired oxygen, a diffusion impairment across the disorders. 4. Any neuromuscular disorder that affects the alveolar-capillary intrapulmonary shunting, muscles of ventilation can cause membrane, acute and chronic respiratory failure. and a reduction of oxygen in mixed venous blood.

Ventilation–Perfusion Mismatch Ventilation–perfusion mismatch or inequality is the most common pathophysiologic cause of acute hypoxemic respiratory failure. It causes the development of hypoxemia. Hypoxemia can occur by a decrease in

xi

Sindee Kalminson Karpel, MPA, RRT, AE-C,

has been a respiratory therapist since 1980 and is currently professor of cardiopulmonary sciences and respiratory care and chair of the Bachelor of Science completion program in cardiopulmonary sciences in the School of Health Professions at Florida SouthWestern State College in Fort Myers, Florida. She is the author of several textbook ancillaries, continuing education books, and peer-reviewed articles. Sindee served on the founding Board of Directors of the National Asthma Education Certification Board and on the Board of ­Directors of the New York State Society for Respiratory Care and is currently on the Board of Directors of the Lambda Beta Society. She is the recipient of the 2003 NYSSRC Samuel Runyon Memorial Award, the 1990 NYSSRC Practitioner of the Year Award, and the 1988 NYSSRC-SEC Award for Excellence in Respiratory Care. Sindee was born and raised in New York City, New York. She received her bachelor of arts degree in anthropology from Queens College of the City University of New York (1974), a 2-year certificate in Respiratory Care from New York University Medical Center—Bellevue

xii

© TairA/Shutterstock

About the Author Hospital (1980), and a Master of Public Administration degree in healthcare administration from the C.W. Post Campus of Long Island University (1986). Before relocating to Florida, Sindee was associate professor of allied health sciences at the Borough of Manhattan Community College of the City University of New York, where she taught for 10 years. She began her career in respiratory care at Queens Hospital Center in New York, where she was promoted from staff respiratory therapist to day supervisor to assistant director. Sindee also worked as adjunct faculty of the respiratory care program at the Borough of Manhattan Community College from 1982 to 1993. She was also assistant director of respiratory care at Long Island Jewish Medical Center before becoming a full-time educator. Sindee is a Certified Asthma Educator, certificate number 13. She has spent numerous hours volunteering with the American Lung Association of Florida and New York City, the Southwest Florida COPD Community Team, the Asthma and Allergy Network, and at local asthma and COPD events. She is a passionate educator and has mentored numerous respiratory therapists over the past 38 years.

© TairA/Shutterstock

Acknowledgments I

am honored and privileged to be able to complete the work of Anthony James Linz, DO, MPH, the original author of this text. It was his love of pulmonary medicine and teaching respiratory care students that led him to proposing this book and authoring several of the chapters before his death. I share Dr. Linz’s love of teaching and vision to have a pulmonary disease textbook that embodies a student-centered pedagogical ­approach to pulmonary disease.

Thank you to the ancillary contributor, Jean ­ ewberry, for her ability to take my thoughts and N put them into action. Finally, a special thanks to Cathy E ­ sperti and Rachael Souza for giving me the opportunity and assistance to make this book a reality. Sindee Kalminson Karpel, MPA, RRT, AE-C

xiii

A project of this magnitude is never completed without assistance. I would like to thank all the contributors: Sharon Connelly-Merdian, RRT Director of Clinical Education New York City, NY

Raymond Lenius, A.S. Professor Florida SouthWestern State College Fort Myers, FL

Amanda M. Dexter, MS, RRT, RCP, CHSE Clinical Assistant Professor University of North Carolina at Charlotte Charlotte, NC

Heather O’Connell, MS, RRT, CPFT Professor, Respiratory Care Director of Clinical Education Florida SouthWestern State College Fort Myers, FL

Dan Fisher, MS, RRT Director, Respiratory Care/PFT Boston Medical Center Boston, MA

Jeffery Ruiter, MSHI, BSRT, RRT, RCP Program Director Central Piedmont Community College Charlotte, NC

Donna (De De) Gardner, DrPH, RRT-NPS, FAARC, FCCP Associate Professor Texas State University San Marcos, TX

Nicole Smith, RRT Respiratory Care Supervisor HealthPark Medical Center Lee County, FL

Hossein Gharanfolib M.A, RRT-NPS-ACCS, RPFT Instructor Bowling Green State University Norwalk, OH

Charley Starnes, BS, RRT, RCP Instructor Central Piedmont Community College Charlotte, NC

Marnni Elaine Hutchins Instructor Central Piedmont Community College Charlotte, NC

xiv

© TairA/Shutterstock

Contributors

© TairA/Shutterstock

Reviewers Kira M. Anderson, MSA, BHS, RRT Director of Clinical Education Baptist College of Health Sciences Memphis, Tennessee

Mary P. Martinasek, MPH, RRT Professor Hillsborough Community College Tampa, Florida

Lea M. Endress, BS, RRT, RPFT, RCP Professor San Joaquin Valley College Visalia, California

Kathe Rowe, BS.Ed., RRT-NPS Respiratory Therapist Program Director Rose State College Midwest City, Oklahoma

Linda M. Lair, MS, RRT, CPFT Director of Clinical Education University of Missouri Columbia, Missouri

xv

CHAPTER

1 © TairA/Shutterstock

Cardiopulmonary Assessment

“It is only by the methodical examination of every system and organ that we get those comprehensive facts from which we can draw reasonably safe inductions.” —William Osler, MD, Unpublished draft of an address to medical students at the University of Pennsylvania, 1885.

OUTLINE

OBJECTIVES

Introduction Taking a History Providing a Therapeutic Climate Components of the Patient History Vital Signs Temperature Heart Rate Respiratory Rate Blood Pressure Essential Elements of a Pulmonary Examination Observation Inspection Palpation Percussion Auscultation of Breath Sounds Essential Elements of the Cardiac Examination Observation Inspection Palpation Auscultation Neurologic Assessment Level of Consciousness Posturing Pupillary Dilation

1. Outline the essential components of a medical history. 2. Explain the main categories of the review of symptoms. 3. Describe normal vital signs and explain common causes of vital sign alteration. 4. Understand the terminology associated with breathing patterns. 5. Describe each of the elements of a pulmonary assessment. 6. Describe the commonly found adventitious breath sounds and their causes. 7. Review the elements of a basic cardiac examination. 8. Summarize normal and abnormal heart sounds. 9. Describe different neurologic assessment scoring systems often used in the acute care setting. 10. Utilize the Glasgow Coma Scale to assess a patient’s neurologic status.

KEY TERMS Adventitious breath sound Atrial gallop Biot respiration Bradycardia Bradypnea Bronchovesicular breath sound Capillary refill time Cheyne–Stokes breathing Chief complaint (CC) Crackle Cyanosis Decerebrate posturing Decorticate posturing Diastolic blood pressure

Dyspnea First heart sound (S1) Fremitus Gallops Glasgow Coma Scale (GCS) Grunting Heart murmur History of present illness (HPI) Hyperpnea Hypertension Hyperthermia Hypothermia Jugular vein distension Kussmaul respiration

1

2

CHAPTER 1  Cardiopulmonary Assessment Kyphoscoliosis Kyphosis Lordosis Mean arterial pressure Nasal flaring Orthopnea Paradoxical breathing Pectus carinatum

Pectus excavatum Pedal edema Platypnea Point of maximal impulse Pulse pressure Pursed-lip breathing Pyrexia Resonance

Review of system Rhonchi Scoliosis Second heart sound (S2) Smoking history Sternal retraction Stridor Systole

Systolic blood pressure Tachycardia Tachypnea Tracheal (bronchial) breath sound Vesicular breath sound Wheeze

Introduction

Taking a History

Patients with respiratory problems consult with healthcare practitioners because their family or friends have noted some departure from normal health. Patients may be suffering from mild symptoms or may be apprehensive and fearful of a severe illness that may lead to their incapacitation. Understandably, the patient expects a clear and satisfactory explanation provided in simple terms. Patients are not a collection of symptoms, assessment data, dysfunctional organs, and abnormal physiology with imbalanced homeostasis. The patient is human with feelings, emotions, fears, and hopes. Healthcare professionals interacting with a patient should use their scientific knowledge and clinical skill as well as their human attributes, sympathy, kindness, and tact. ­Developing a harmonious and sympathetic relation and demonstrating compassion are imperative for successful patient care. Proper and quality care of the patient with lung disease requires recognizing the etiology and functional abnormalities presented with the disorder. Obtaining adequate and reliable information from various sources will achieve this task. Taking a history, performing a physical examination, evaluating radiographic studies, assessing other system functions, and other diagnostic tests are methods utilized to provide the necessary information. Assessment is, without a doubt, the most important skill required to initially evaluate the patient with a respiratory disease and recognize the health problems facing the patient. The patient’s perception of the respiratory care practitioner’s (RCP) competence is of utmost importance. Therefore, it is imperative that any healthcare provider’s affect be genuinely caring toward the patient; skill and a caring attitude must coexist to ensure professional and trustworthy relationship.

The medical history provides a comprehensive picture of a patient’s health and health problems. It is a detailed record that contains pertinent facts about the patient’s disease process. The medical history provides data regarding variables affecting a patient’s health so as to develop an individualized plan. This is an essential part of the entire process of patient assessment performed by the respiratory therapist.1 The characteristics of the chief complaint (CC) and associated symptoms need ascertaining. The information gathered while taking the patient’s history is the basis for the extent of the assessment. Obtaining a comprehensive history is time consuming, and the acuity of the patient’s condition may limit the practitioner’s ability to assess all the body systems. Therefore, many practitioners perform a focused assessment of the body systems of concern. Understandably, the cardiopulmonary system is of primary importance for respiratory care professionals. A list of the components of a patient medical history appears in Table 1-1.

KNOWLEDGE CHECK QUESTIONS 1. True or False: Developing a sympathetic relationship with the patient is imperative for successful patient care. 2. True or False: Obtaining adequate and reliable information from various sources will help identify a patient’s functional abnormalities.

Providing a Therapeutic Climate The patient’s impression of the healthcare practitioner’s competence is of the greatest importance. When the RCP is perceived of as being uncaring and incompetent, the patient may remember that attitude most vividly.1 Even worse, that uncaring attitude and perception may define (characterize) for that patient other members of the profession. Clinicians must dress appropriately because a professional appearance conveys respect for the patient. A patient’s opinion of the healthcare provider often is based on the physical appearance. At the core of successful history taking is skilled and patient-centered communication through which the respiratory therapist and the patient establish a rapport.2 A healthcare provider can communicate a caring attitude and competence by displaying the attributes listed in Table 1-2.

Components of the Patient History The first step in diagnostic thinking is to carefully and thoroughly review the patient history. This entails identification of the who, what, when, and where of the patient’s current respiratory condition. Obtaining a patient’s history requires a systematic approach and includes identification of the patient’s CC, history of present illness (HPI), past medical history (PMH), medication history, social history, occupational and environmental history, family history, and a review of symptoms (ROS).

Taking a History

TABLE 1-1 Example of Components of the Medical History Demographic data

CC

Patient name Address Age Gender Race/ethnicity Education Marital status Religion Languages spoken Admitting diagnosis (if available) Patient’s physician Brief description of reason for medical care The particular reason for this visit made by patient or family member List of complaints in order of acuity

HPI

Specific details regarding the presenting illness in chronologic order

PMH

Previous hospital admissions Past operations Major illnesses Accidents Injuries Pregnancies

Medication history

Current prescription medications Over-the-counter medications Allergies

Social history

Birthplace Marital status Living arrangements Smoking history Alcohol use Drug use Sexual activity

Family history

Relatives and causes of death Family diseases

Occupational/environmental history

Occupation Work environment and exposure Military service

Review of symptoms

General symptoms Skin and nails Head, eyes, ears, nose, and throat (HEENT) Endocrine Respiratory Cardiac/cardiovascular Hematologic Lymph Gastrointestinal (GI) Genitourinary Musculoskeletal Neurologic Mental status

TABLE 1-2 Attributes Supporting a Caring and Professional Climate Professional in appearance Professional in conduct Caring demeanor Eye contact Respectful Active listener Honest Nonjudgmental Unhurried

Case Study: Patient History An RCP is asked to assess a 66-year-old woman complaining of rapid onset of shortness of breath (SOB). She states, “I cannot catch my breath.” She is coughing up a yellowish sputum, is diaphoretic, and feeling feverish, although she has not taken her temperature. Questions 1. What other important questions should be asked by the RCP? 2. What possible pulmonary problems (working diagnosis) are suggested by the symptoms at this point? 3. What is the significance of the patient complaining of sweating? Answers 1. The RCP should ask the patient if she has chest pain, nausea, dizziness, or blood in her sputum. The RCP should also ask about any history of lung disease or cigarette smoking. 2. The pulmonary problems based on interview suggest pneumonia, acute bronchitis, asthma, and acute exacerbation of chronic obstructive pulmonary disease (COPD). 3. The sweating is significant because it is consistent with a fever that may be caused by infection. Fever may be a contributing factor to SOB because of an increase in oxygen consumption, increased CO2 production, and an increase in the drive to breathe.

3

4

CHAPTER 1  Cardiopulmonary Assessment

Chief Complaint The chief complaint is the problem or group of symptoms that brings the patient to the physician or hospital for health care. To elicit information about the CC, start with an open question, for example, “What is the problem?” or “Tell me about the problem.”3 The CC is a subjective statement made by the patient (patient’s description of the problem) and should be documented using the patient’s words. For example: “I am short of breath.” Documentation of more specific details is in the HPI.

History of Present Illness The history of present illness describes the detailed information pertinent to the CC. Once the patient has completed his or her answer to the initial CC question, the practitioner moves on to clarify and focus using specific questions. Closed questions provide extra detail and sharpen the patient’s story.3 This clarification includes a description of the onset of the problem, the date the symptoms were noted, and whether the symptoms developed gradually or suddenly. Also included is the setting in which the signs and symptoms developed. Past medical problems, hospitalization, symptoms, and treatments are noted as well as whether the problems are resolved, ongoing, or recurrent. The variables included when taking an HPI are summarized in Table 1-3. A focused pulmonary history is a specialized version of the HPI that focuses on symptoms related to cardiopulmonary disease. A complete pulmonary history should include questions regarding the presence or absence of a cough, sputum production, hemoptysis, wheezing, chest tightness, chest pain, and breathlessness.4 The most common complaint by patients with pulmonary problems is the feeling of SOB or breathlessness. Dyspnea is the term used to describe the TABLE 1-3 Items to Include in the History of Present Illness

uncomfortable awareness of difficult or labored breathing associated with feeling short of breath. Dyspnea is a subjective symptom influenced by the patient’s reaction, sensitivity, and emotional state. Not all patients with SOB use similar terms to describe their dyspnea. Patients with asthma tend to use the phrase “my chest feels tight,” patients with fibrosis state “my breathing is too fast,” and patients with congestive heart failure (CHF) express their dyspnea with the statement “I feel like I am suffocating.” Dyspnea is due to an increase in the work of breathing out of proportion to the level of activity. In assessing for dyspnea, it is important to determine whether it is chronic or acute. In the acute episode, the event is recent and often severe. The circumstances in which a patient’s dyspnea develops should be determined and evaluated. Dyspnea may occur with certain body positions. Orthopnea indicates dyspnea in lying down position, which is a characteristic symptom associated with heart failure. In reclining position, there is an increase in venous return to the failing heart; this additional fluid may accumulate in the lungs and lead to dyspnea. Many patients with an advanced pulmonary disease must assume an upright position to breathe well. Platypnea is dyspnea in the upright position, which improves by lying down.

Past Medical History The PMH gives an insight into the health status of the patient up to the point of the present illness. This section contains information about the patient’s past illnesses and treatment, including previous hospital admissions, prior surgeries, major illnesses (such as diabetes, hypertension, or heart disease), and accidents. When taking a PMH, it is important to ascertain the diagnosis, dates, sequence, and management of each diagnosis.3 Other information documented here include childhood diseases and development, allergies, and immunizations. Neglecting the PMH can cause inadvertent discontinuation of essential medications, prescription of incorrect dosages of chronic medications, duplication of diagnostic testing, neglect of an earlier prescription, or disruption of plans made by previous clinicians.5 Problems may become further compounded given that some of the most difficult patients to treat are also those with the most complex medical histories.5

Component

Elements

Onset

Date, time, sudden, or gradual

Location

Where is the problem? Did it spread?

Duration

Symptom duration

Medication History

Character

Quantity and quality of symptoms

Associated manifestations

The setting in which the symptoms began

Relieving factors

Factors that diminish or aggravate symptoms

Treatment

Medications, remedies that relieve or exacerbate symptoms

Medication information is crucial. Current medications serve as a reminder of other existing conditions that the patient may have forgotten to mention earlier in the interview. Medications taken may contribute to the current problem or influence the choice of medications for the current problem. It is important to ask about over-the-counter medications as well as herbal remedies because all these can have adverse reactions or drug interactions. Numerous drugs affect gastric pH,

Hess, Respiratory Care Principles and Practice 3rd edition, 2016

Taking a History enzyme quality, normal renal excretion, intestinal bacteria, and blood chemistries. Drugs may also confuse the significance of certain signs and symptoms. Medication adherence is an important part of taking a medication history. Finding out the level of adherence and any reasons for nonadherence can be of significance in the future treatment of the patient.3 Also, an enquiry into drug allergies and sensitivities is necessary.

Social History A patient’s health and well-being are affected by social, personal, and occupational factors. Knowledge of the patient’s background is useful, not only for diagnosis but also for disease management. How patients think, live, and behave influence how they cope with illness.6 Social history includes getting to know how the patient’s illness impacts the patient at home, as well as at work. Information obtained from the social history include leisure interests, physical exercise, living arrangements, children, sexual relationships (or lack of them), tobacco use, drinking alcohol, and recreational drug use.6 Smoking harms every organ in the body and causes many diseases that reduce the individual’s general health. The smoking history is an essential part of the patient interview.4 The practitioner documents the type of substance the patient smokes or uses: cigarettes, cigars, pipe, snuff, chewing tobacco, marijuana, or other recreational drugs. The length of time of lung exposure to tobacco smoke is vital information and quantifies smoking in pack-year: the number of cigarette packs smoked per day multiplied by the number of years smoked. Occasionally, a patient will smoke less than one pack per day. Each pack has 20 cigarettes. Therefore, 10 cigarettes per day make half a pack per day, and so on (Box 1-1). Inhalation of other substances, such as marijuana or crack cocaine, is associated with pulmonary symptoms such as a cough, sputum production, and wheeze.4 Illicit drug inhalation has cardiovascular effects as well. The amount and frequency of drug use are relevant information to ascertain in social history. Smoking cessation and assistance with drug use are valuable in the improvement of the patient’s overall health. For those patients who are willing to try

BOX 1-1 Examples of Tobacco Smoking History 1. A patient who currently smokes two packs per day for 35 years has a (2 packs/day × 35 years =) 70 pack-year history of smoking. 2. A patient who smokes five cigarettes per day (5 cigarettes/day ÷ 20 cigarettes/pack = ¼ pack/day) for 25 years has a (¼ pack/day × 25 years =) 6.25 pack-year history of smoking.

and quit, the clinician should offer assistance and follow-up care.4 Excessive drinking has immediate effects that increase the risk of many harmful health conditions, including alcohol poisoning. Over time, chronic alcohol consumption use can lead to an increase in long-term health risks such as hypertension, cardiomyopathy, stroke, liver diseases, and digestive problems.7 Alcoholics are prone to the development of aspiration pneumonia, as well as many other health issues.4 When quantifying alcohol consumption, one drink is usually 5 oz of wine, 12 oz of beer, or 1.5 oz of 80-proof distilled liquor.8 For women, four or more drinks in a day are excessive; for men, five or more.8 Past and present patterns of drinking alcohol are often assessed, in the hospital situation, by using the CAGE system, which uses four questions to elicit a view of alcohol intake.3,6 These items are shown in Box 1-2. Scores of two or more positive answers indicate a significant alcohol problem.3,6

Occupational and Environmental History Taking a patient’s history needs to include information about previous and current employment. This is important because aspects of employment other than the job itself can influence social well-being if illness precludes a return to work.3 Patient management and prognosis are affected significantly by the knowledge of this information. For example, patients with occupational asthma or hypersensitivity pneumonitis often cannot be managed adequately without cessation of exposure to the offending agent.9 Exposure to inorganic, as well as organic dust, is associated with the development of respiratory diseases. Inorganic dust includes asbestos, silica, coal, beryllium, aluminum, chromium, cobalt, nickel, and tungsten. Organic dust includes cotton, grain, fungal spores, vegetable products, insect fragments, animal dander, bird and rodent feces, toxic chemicals, biomass smoke, diesel exhaust, and others.9 These exposures occur in mining, farming, construction, ship repair, and a variety of industries.9

BOX 1-2 CAGE Questionnaire C

Have you felt the need to Cut down on your alcohol intake or drinking?

A

Have people Annoyed you by criticizing your drinking?

G

Have you ever felt Guilty about your drinking?

E

Eye-opener: Have you ever had a drink to steady your nerves in the morning?

Reproduced with permission from Lloyd H, Craig S. A guide to taking a patient’s history. Nurs Stand. 2007;22(13):42–48. doi:10.7748/ns2007.12.22.13.42.c6300.

5

6

CHAPTER 1  Cardiopulmonary Assessment Environmental exposure history is also necessary. Environmental exposure to contagious diseases, travel, and the home environment also have an impact on the development and course of cardiopulmonary disease.4 Indoor, as well as outdoor, exposure exacerbates existing pulmonary problems and increase the risk for cardiopulmonary diseases.9 Exposure to secondhand tobacco smoke, radon gas, wood smoke, and other biologic agents generated indoors need consideration. Pets may also play a significant role in the development of certain types of lung disease. For example, pet shop employees, bird fanciers, and veterinarians may develop a particular bacterial infection associated with pet birds and poultry.4 A careful environmental history is imperative in identifying asthma triggers. Hobbies may also impact pulmonary diseases, such as woodworking and gardening.

Family History Some disorders are considered familial or hereditary. Obtaining a patient’s family history can reveal the presence of a genetic predisposition to certain diseases. For example, the presence of cerebrovascular disease or dementia in a close blood-related relative might help guide the management of the patient.3 The family health history needs to include parents, siblings, and grandparents. The major diseases included in the family history are hypertension, cancer, heart disease, lung disease (including asthma, COPD, pneumonia, and tuberculosis [TB]), diabetes, stroke, kidney disease, thyroid problems, and Alzheimer disease.4 People who have a close family member with a chronic illness may have a higher risk of developing that illness than those without such a family member.

Review of Symptoms or Review of Systems The review of symptoms (ROS), also known as a review of systems, provides an opportunity for the RCP to collect data verbally. The focus of the ROS is on the system or systems that are affected by the present illness and relate to the patient’s complaint. Documentation of only pertinent information makes this problem-focused. This review is based on a list of questions, arranged by organ system. It is designed to uncover dysfunction and disease. Unfortunately, there is no gold standard for ROS. However, the systematic analysis of any symptoms is best achieved by a detailed assessment of its timing, influences, nature, and associated features (TINA).6 The timing of a symptom relates to its onset, duration, pattern, and progression. Onset may be sudden, gradual, or insidious. Influences refer to things that aggravate the symptom and relieve the symptom. The nature of the symptom includes its characteristics, such as description, and its severity. The associated features include a description of other symptoms that may have occurred at the same time and the relationship of these other symptoms to the primary symptom. Table 1-4 shows the main categories and examples of findings in each category. The following box is a case study demonstrating the importance of the ROS.

Vital Signs Vital signs are the four signs of life: temperature, pulse, respiratory rate (RR), and blood pressure (BP). These are the most frequently made clinical assessments because they are easy to obtain and provide useful information about the patient’s clinical condition.10 Most acute medical problems cause abnormal vital signs that become more irregular as the problem increases

TABLE 1-4 Review of Systems: Main Categories and Examples Categories

Examples

General symptoms

Weight loss, weight gain, fatigue, difficulty sleeping, fevers, chills, sweats, chronic pain

Skin and nails

Color, temperature, appearance, skin eruptions/rashes, itching, clubbing

HEENT

Head—dizziness, loss of consciousness, fainting, head injury, concussion Eyes—Blurred vision, double vision, eye discharge, red eye, pupillary reaction Ears—Pain, hearing loss, tinnitus, vertigo Nose—Nasal discharge, sneezing, nasal flaring, sinus pain, postnasal drip, nosebleeds Throat—Vocal cord pathology, voice change, sore throat, tooth pain, bad breath, appearance of gums

Endocrine

Diabetes, thyroid enlargement, thyroid tenderness, polyuria, weight gain, weight loss

Respiratory

Chronic or past pulmonary disorders, SOB with or without exertion, chest pain, cough, hemoptysis, wheezing, snoring, chest deformity, chest trauma

Cardiovascular

Chronic cardiovascular disorders, chest pain or pressure, SOB at rest or with exertion, orthopnea, paroxysmal nocturnal dyspnea, peripheral edema, syncope, palpitations, leg pain or cramps with ambulation, foot ulcers that are difficult to heal

Vital Signs

Categories

Examples

Hematologic

Chronic or past hematologic disease, fevers, chills, sweats, weight loss, abnormal bruising or bleeding

Lymph nodes

Tender, enlarged, swollen

GI

Chronic or past GI disorders, heartburn, abdominal pain, difficulty swallowing, nausea, vomiting, abdominal swelling or distension, jaundice, hematemesis, tarry stools, use of caffeine

Genitourinary

Urine output

Musculoskeletal

Known disease, trauma, joint swelling, restricted motion

Neurologic

Known disease, weakness, tremors, seizures, paralysis, balance problems, headache

Mental status

Depression, restlessness, anxiety, mood swings, sleep disturbances, known mental health disorder

Case Study: Review of Symptoms Mr. Brown, a 59-year-old Caucasian man, presents to the emergency department (ED) with a CC of SOB and chest pain. The chest pain began 8 hours ago while Mr. Brown was working in his yard. His SOB started while resting in the reclining position about an hour before he presented himself to the ED. The ED physician is busy and asks the respiratory therapist to assess and evaluate the patient. The RCP enters the patients room and introduces herself and explains what she is about to do. She asks the patient about the nature of his chest pain. (Chest pain could be pleuritic or nonpleuritic in nature. Constant chest pain under the sternum with a heavy pressure feeling on the chest is consistent with inadequate oxygen delivery to cardiac muscles from low perfusion and is called ischemia. Pleuritic pain is localized posteriorly or laterally and worsens with coughing or deep breathing.) The RCP asks the following questions about Mr. Brown’s chest pain: 1. Does the chest pain increase with deep breath? 2. Does the pain radiate to the arms and shoulders? 3. How severe is the pain? 4. Is the chest pain associated with nausea, indigestion, weakness, and profuse sweating (diaphoresis)? Next, the RCP assesses the severity of Mr. Brown’s SOB. The severity of the SOB is assessed by asking the following questions: 1. Does it occur at rest or only with exertion? 2. Has SOB occurred before this incident?

3. Does the SOB occur in reclining position (orthopnea)? 4. Does the SOB improve when sitting upright? After gathering information about Mr. Brown’s chest pain and SOB (CCs), the RCP asks about other possible symptoms such as fever, cough, sputum production, hemoptysis, and swollen ankles. (Additional information to enquire about include heart disease, family history of heart disease, and the patient’s stress levels. Social habits need to be identified as risk factors for heart and lung disease.) Mr. Brown explains that the chest pain is centrally located and radiates to his left arm and jaw. The chest pain started when he started pushing the lawn mower (exertion increases cardiopulmonary workload and oxygen requirement). The pain decreased with rest and is not affected by breathing. Mr. Brown has not taken any medication for his chest pain. He describes his SOB as severe and says it awakens him after going to bed. It improved when he sat upright. He describes his SOB as a feeling of suffocation. Mr. Brown denies any other symptoms except for having some diaphoresis, weakness, and nausea, but denies vomiting. He has been smoking two packs of cigarettes a day for the past 43 years. Case Review Assessment Upon completing the interview and information gathering, the respiratory therapist’s evaluation is as follows: Chest pain: Mr. Brown’s explanation of his chest pain is the classic description of cardiac pain. The pain is probably due to narrowing of coronary (Continues)

7

8

CHAPTER 1  Cardiopulmonary Assessment

Case Study: Review of Symptoms (Continued ) vessels that prevents adequate perfusion to the heart muscle and inadequate blood flow to the heart muscle results in an ischemic myocardium. Exertion requires more blood flow to the heart muscle and, in this case, the inability of deliver more oxygen to meet the additional demand causes the chest pain to worsen. SOB: This is most likely due to pulmonary edema (patient feels as if he is suffocating). The pulmonary edema is caused by left ventricular failure and increase

KNOWLEDGE CHECK QUESTIONS 1. True or False: A patient who smoked 2½ packs of cigarettes a day for 25 years has a 62.5 pack-year smoking history. 2. True or False: The CAGE questionnaire is used to investigate illicit drug use.

in severity.11 Chronic conditions may not result in abnormal vital signs as compensatory mechanisms take effect.11 The fifth vital sign is blood oxygen saturation or pulse oximetry. Although it is not always considered a vital sign, the patient’s oxygen saturation is often included with the vital sign assessment. A comparison of the measurements obtained during the initial assessment of a patient’s vital signs is made with the normal values (Table 1-5). After documentation of several vital sign measurements, these data are then used as a baseline for subsequent measurements and trending.

Temperature The human body has a narrow temperature range within which it operates. Body temperature measurement is an indicator of a patient’s physiologic state; it varies from person to person and is an important measurement for decisions in medical diagnosis, bedside care, treatment, and the need for laboratory tests. Thermoregulation is the body’s mechanism to maintain body temperature within its narrow operating range and is carried out by the hypothalamus. The body’s operating range normally varies because of diurnal variation and cellular metabolism and results will vary depending on the assessment location. The core temperature, the most accurate body temperature, is assessed using a rectal or tympanic measurement; however, oral temperature measurements are very common. Under normal conditions, the body can maintain a normal temperature of 37 ± 0.5°C (98.6 ± 1°F).

in pulmonary capillary hydrostatic pressure (pulmonary capillary filtration pressure). Respiratory Therapist’s Recommendations The respiratory therapist’s report to the physician includes a strong suspicion of heart failure. The respiratory therapist recommends oxygen therapy, diuretics, a 12 lead electrocardiogram (ECG), and chest radiograph. The respiratory therapist ruled out pneumonia, because Mr. Brown did not have any fever, chills, cough, and sputum production.

TABLE 1-5 Normal Vital Sign Values for Adults Temperature

37°C or 98.6°F

Pulse

60–100 beats/minute

RR

12–20 breaths/minute

BP

Systolic 90–140 mm Hg Diastolic 60–90 mm Hg

Pulse oximetry

≥95%

Infants and children have a higher RR, higher pulse rate, and lower BP values than adults.

The purpose when measuring body temperature is to estimate changes in core temperature. A site that quantitatively and rapidly reflects changes in arterial temperature and is independent of local blood flow or environmental changes would appropriately estimate core temperature.12 Elevated body temperature, also known as fever or pyrexia, can arise from disorders affecting every body system. In most patients, a fever is a temperature of >38.3°C (101°F).4 Fever is one of the ways the immune system attempts to combat infection from viral, fungal, or bacterial organisms. However, in the absence of other signs, fever usually has little diagnostic significance. Fever causes an increase in metabolic rate, resulting in an increase in oxygen consumption and carbon dioxide production. This results in an increased RR and heart rate to accommodate the increased carbon dioxide production and oxygen requirement of the cells.11 A persistent high fever (>40.6°C or >105°F) represents an emergency. Hyperthermia is an elevated body temperature due to excessive heat production or inadequate heat dissipation from heavy exertion in a hot, humid environment. A body temperature below normal is hypothermia and is most often caused by prolonged exposure to cold. This occurs in patients with head injuries that damage the hypothalamus and in drowning victims.11

Vital Signs There are also some medications that increase the patient’s risk of hypothermia. Hypothermia reduces oxygen consumption and carbon dioxide production and may cause a patient to breathe shallow and have a low pulse rate.10 The hypothalamus is the suspected cause of hypothermia when there is a significant neurologic incident (stroke or head trauma) or the development of a tumor.

Heart Rate A pulse results from the force of ventricular contraction (systole) required to move the blood forward in the vascular system. It is a measurement of the heart rate that may be assessed by taking the patient’s pulse, using pulse oximetry, auscultating the heart, or by electrocardiography. The pulse rate and rhythm are a quick and easy assessment via the palpation of any accessible artery; the radial artery is the most common assessment site for this purpose. A practitioner may count the pulse for 15, 30, or 60 seconds and then mathematically calculate to the rate per minute. The 30- or 60-second count is most accurate, allowing for assessment of the quality of the pulse as well as the rate. The normal heart rate for adults is 60–100 beats/minute. See Table 1-6 for normal and abnormal rates. Quantitative pulse assessment reveals normal, rapid (tachycardia), or slow (bradycardia) rates. Tachycardia is a normal physiologic response to vigorous activity, such as running or climbing stairs.13 It is an abnormal physiologic response associated with many pathophysiologic conditions such as hypoxia, anemia, hypotension, cardiac disease, uncontrolled pain, and fever. Certain drugs, such as epinephrine, atropine, caffeine, nicotine, and cocaine, may cause tachycardia. Bradycardia is less common than tachycardia but can occur with hypothermia, as a side effect of medications, with certain cardiac arrhythmias, and with traumatic brain injury.10 Qualitative pulse assessment, taken during pulse rate assessment, includes rhythm and strength. The rhythm and strength or amplitude need to be noted TABLE 1-6 Heart Rate in Adults

using common terminology for describing pulse ­quality13 (Table 1-7). Cardiac arrhythmias cause pulses to be irregular. An ECG will determine the type of arrhythmia. An absent or a weak pulse may be bilateral or affect only one e­ xtremity. When bilateral, an absent pulse is a vital indicator of life-threatening conditions such as cardiac arrest, shock, or arrhythmia. Diminished blood flow causes a weak, thready pulse and is usually due to ­hypovolemia, hypotension, shock, myocardial infarction, CHF, poor blood flow, or blood clots.13 In a healthy person, a bounding pulse develops because of exercise, pregnancy, and periods of anxiety. However, this sign also results from fever and certain endocrine, hematologic, and cardiovascular disorders that increase the basal metabolic rate.14 The heart rate is higher in infants and children than in adults. The normal heart rate range for infants, ­especially newborn to 3 months of age, varies widely between an awake rate and a sleeping rate. The normal heart rate becomes that of an adult after the age of 10 years (Table 1-8).

Respiratory Rate A normal range for RR for an adult is 10–20 breaths/ minute. An RR greater than 20 breaths/minute is tachypnea, and slower than 10 breaths/minute is bradypnea. As with pulse, the RRs in children vary with age and slow down as children grow (Table 1-9). Tachypnea may result from reduced arterial oxygen tension or arterial oxygen content, decreased perfusion, or increased oxygen demand.14 The causes of increased oxygen demand include anxiety, exertion, fever, pain, or as a compensatory mechanism for a metabolic acidosis, pulmonary irritation, stretch receptor stimulation, or a neurologic disorder of the respiratory center.14 Tachypnea and shallow breaths are the hallmarks of restrictive breathing disorders such as atelectasis, pulmonary edema, pneumonia, pneumothorax, and pulmonary fibrosis.11 Bradypnea is usually due to central nervous system (CNS) depression from an overdose of CNS depressants TABLE 1-7 Qualitative Assessment of the Pulse

Classification

Rate (Beats/ Minute)

Common Causes

Normal

60–100

Normal

Tachycardia

>100

Hypoxia, cardiac disease, fever, exercise, and anxiety

Bradycardia

10 years

 60–100

50–90

TABLE 1-9 Normal Respiratory Rate by Age (Breaths/Minute) Age

Normal Respiratory Rate

12 years

12–18

such as opiates, benzodiazepines, barbiturates, and alcohol. Other causes of bradypnea include hypothermia and severe hypoxia.13 Assessing the respiratory pattern provides additional important information about the patient. The respiratory motions (inspiration and expiration) are apparent over the chest and abdomen. Under normal conditions, inspiration is shorter than expiration, the normal I:E ratio is 1:2. The change in respiratory pattern associated with respiratory disease is due to changes in breathing rate, tidal volume, rhythm, and the ratio of inspiration to expiration. The diaphragm is the primary muscle of inspiration. A respiratory cycle includes an inspiratory phase and an expiratory phase. Inspiration is an active process that requires the expenditure of energy and the use of oxygen to produce that energy (adenosine triphosphate [ATP]). During inspiration the diaphragm contracts and causes the intrathoracic pressure to decrease. This decrease in intrathoracic pressure, in turn, produces a subatmospheric pressure that causes airflow through the airways and alveolar expansion. At the end of inspiration, the diaphragm relaxes, and the lung recoil causes an increase in alveolar pressure relative to atmospheric pressure. This passive process that causes the air to flow out of the lung is the expiratory phase of respiration.

Breathing Patterns A breathing pattern that is fast and deep is hyperpnea and usually results in hyperventilation (a lowered Paco2). Kussmaul respiration is rapid and deep breathing associated with metabolic acidosis, usually diabetic ketoacidosis.

Cheyne–Stokes breathing is a pattern of slow, shallow breaths, which increases in depth and rate followed by periods of apnea. This breathing may be normal in young children and the elderly. However, this pattern of breathing is common to individuals with cerebral disease and CHF. Biot respiration is a pattern of a burst of uniform, large tidal volume followed by periods of apnea. Biot respirations are symptoms of increased intracranial pressure and meningitis. Figure 1-1 shows various patterns of breathing.

Blood Pressure Arterial BP is the force exerted by the circulating intravascular volume of blood on the wall of the arteries. This pressure occurs during ventricular contraction and pushes the blood forward into the aorta and pulmonary arteries. BP assessment includes four arterial pressure measurements. Systolic blood pressure (SBP) is the pressure measured during ventricular contraction. Diastolic blood pressure (DBP) is the pressure measured during ventricular relaxation and is a result of the elastic recoil of the arteries and arterioles. Pulse pressure (PP) is the difference between the systolic and diastolic pressures and is dependent on stroke volume and arterial wall elastic properties. Lastly, the mean arterial pressure (MAP), or perfusion pressure, drives the blood through the systemic vasculature from the arteries to the arterioles, capillaries, venules, veins, and back to the heart. It can be calculated by the following formula: MAP = (SBP + 2[DBP]) ÷ 3. The normal BP varies with age, body size, and underlying pathology. Normally, BP values rise from birth and reach the normal adult values of 120/80 mm Hg around age 18 to 20 (Box 1-3). An SBP continuously ≥140 mm Hg or a DBP continuously ≥90 mm Hg is hypertension (Table 1-10). Numerous medical conditions cause elevated BP, including myocardial infarction, kidney disease, Cushing syndrome, anemia, and essential hypertension. A sustained BP of less than 90/60 mm Hg is ­hypotension. It occurs from a decrease in cardiac ­output, peripheral vasodilatation, or hypovolemia. A hypotensive crisis exists if the patient’s SBP is less than 80 or 30 mm Hg below the patient’s known ­baseline. Shock is most likely, and quick action is necessary. PP normally increases during exercise. It abnormally increases in patients with atherosclerosis of the larger arteries. Heart failure or hypovolemia causes a decrease in PP. Normal MAP is 80–100 mm Hg. An MAP of >60 mm Hg is necessary to perfuse the vital organs of an average individual under most circumstances. An MAP 20 breaths per minute

FIGURE 1-1  Patterns of respiration. Modified from Mosby’s Guide to Physical Examination, Seidel HM, Ball JW, Dains JE, et al., Copyright Elsevier (Mosby) 1999.

BOX 1-3 Normal Average Blood Pressures (mm Hg) by Age Newborn 80/60 ƒƒ Infant 90/60 ƒƒ Children 110/70 ƒƒ Adult 120/80 ƒƒ

KNOWLEDGE CHECK QUESTIONS 1. True or False: Cardiac arrhythmias are identified using pulse rate. 2. True or False: A patient with a BP of 145/95 mm Hg has a normal MAP.

Essential Elements of a Pulmonary Examination

TABLE 1-10 Stages of Hypertension

Category

Systolic Blood Pressure (mm Hg)

Diastolic Blood Pressure (mm Hg)

Prehypertensive

120–139

or

80–89

Hypertension stage 1

140–159

or

90–99

Hypertension stage 2

≥160

or

≥100

Hypertensive crisis

>180

or

>110

Data from U.S. Department of Health and Human Services, National Institutes of Health, NHLBI. JNC 7 Express, The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. 2003. NIH Publication No. 03-5233, December 2003.

Performing a directed physical examination enhances the already gathered history and focuses the diagnostic process by searching for specific signs that either confirm the findings or differentiate between various conditions that might explain the current symptoms.15 The pulmonary examination requires only a stethoscope; eyes, ears, and hands of the clinician; and the clinician’s skill in eliciting and recognizing abnormal findings.16 There are five components to the pulmonary examination. These components are observation, inspection, palpation, percussion, and auscultation. The primary focus of this discussion is not to elaborate on the details of a chest examination but to examine a few of the basic principles; the primary focus is on selected aspects of the examination and the mechanisms that produce abnormalities.16

11

12

CHAPTER 1  Cardiopulmonary Assessment

Observation Observation of the patient begins when the respiratory therapist walks through the door to the patient’s room. It includes a quick review of the patient and the patient’s environment. The environment includes observing for equipment being used, as well as for any safety issues. The equipment can be as simple as a nasal cannula, intravenous solutions, or as sophisticated as life support equipment and a dialysis machine. A patient’s facial expression can reveal distress or pain, alertness, mood, and mental status. Body position can reveal respiratory distress if sitting upright or leaning forward with elbows on the knees or on the arms of the chair in the “breath saver” position. The respiratory therapist needs to be able to identify signs of respiratory distress such as nasal flaring, pursed-lip breathing, cyanosis, and diaphoresis (excessive sweating) during observation (Table 1-11). Nasal flaring occurs when the external nares flare outward during inhalation. This occurs most often in infants with respiratory distress, indicating an increased work of breathing. Patients with COPD adopt the pursed-lip breathing technique to create resistance to exhalation flow. This creates an increased resistance, which acts as a mechanism to keep the airways open and allow for a complete exhalation without airway collapse. The presence of pursed-lip breathing, especially while at rest, could mean the patient is in distress. Central cyanosis is present in patients with respiratory disease that reduces oxygen saturation and arterial oxygen content. This cyanosis is often due to severe hypoxemia and requires immediate further assessment to determine the cause. Respiratory therapists must be aware that lack of cyanosis does not indicate adequate oxygenation. Cyanosis occurs when the concentration of desaturated hemoglobin is 5 g or more. Excessive sweating TABLE 1-11 Elements of Observation Observation

Reveals

Facial expression

Distress Pain Alertness Mood Mental status

Nasal flaring

Respiratory distress, especially in infants

Patient position

Inability to breathe in reclined position or distress

Pursed-lip breathing

Patient with COPD in distress while at rest

Central cyanosis

Serious, life-threatening situation

Diaphoresis

Serious, life-threatening disorder when it occurs while at rest

(diaphoresis) while at rest is an early sign of disorders that can be life-threatening. Diaphoresis is known to accompany heart failure, myocardial infarction, shock, and pneumonia.

Inspection Inspection is the use of our eyes and looking closely at the patient to gather information; this is the most informative phase of the physical examination. Inspection reveals valuable information about the patient’s degree of illness and distress. An in-depth knowledge of anatomical structure and function is imperative to the interpretation of physical examination findings regarding underlying pathologic process. Table 1-12 shows a review of the elements of inspection.

Jugular Vein Distension The most common cause of jugular vein distension (JVD) is right-sided heart failure (cor pulmonale) secondary to increased pulmonary vascular resistance as a result of chronic hypoxemia. Right-sided heart failure may be secondary to chronic left-sided heart failure. JVD may be present because of hypervolemia or increased impedance to venous return to the right atrium. Figure 1-2 shows how to estimate JVD.

Tracheal Position Inspection of the neck is a valuable tool in evaluation of the tracheal position. The trachea is located anteriorly, TABLE 1-12 Elements of Inspection Inspection

Reveals

JVD

Right heart failure, hypervolemia, decreased blood return to right heart

Tracheal position

Air or fluid in the pleural space (e.g., pneumothorax, hemothorax) on the opposite side, atelectasis on affected side

Accessory muscle use

Increased work of breathing

Paradoxical breathing

Flail chest and/or weakened diaphragm

Chest configuration

Barrel chest from obstructive lung disease Restrictive lung disease from pectus carinatum, pectus excavatum, kyphosis, kyphoscoliosis, lordosis, or scoliosis

Pedal edema

Right heart failure, hypervolemia, decreased blood return to right heart

Essential Elements of a Pulmonary Examination

Internal jugular vein External jugular vein Sternocleidomastoid

45° Clavicle

Manubrium of sternum

FIGURE 1-2  Jugular vein distension. To estimate jugular vein pressure (JVP), position the patient supine at a 45° angle. Visualize the internal

jugular vein as it ascends the side of the neck between the two heads of the sternocleidomastoid muscle. Measure the height of the distension as a vertical column of blood in relation to the sternal angle. Normal JVP ≤ 3–4 cm above the sternal angle. JVP may increase because of right heart failure (e.g., cor pulmonale), left heart failure, constrictive pericarditis, pleural effusion, obstructed vena cava, and other cardiopulmonary disorders.

in the midline of the neck. Check the centrality of the trachea by inserting the tip of the index finger into the suprasternal notch. Allow the finger to slip to either side of the trachea. If the finger slips more easily to one side or the other, the trachea is not midline.6 The trachea will shift toward an area of the collapsed lung and away from areas of increased pressure, from fluid or air in the pleural space (e.g., tension pneumothorax, hemothorax, large pleural effusion).

Accessory Muscle Use When the diaphragm is severely depressed by the increase in residual volume and functional residual capacity, or air trapping, the accessory muscles of inspiration are activated. Normally, accessory muscles of inspiration are prominent during exercise. The use of accessory muscles, at rest, is an indication of respiratory distress, increased work of breathing, and oxygen consumption. The major accessory muscles of inspiration include the scalene, sternocleidomastoid, pectoralis major, and the trapezius. The accessory muscles of expiration are often used to overcome significantly increased airway resistance due to increased airway narrowing, loss of elasticity, and airway collapse associated with chronic obstructive pulmonary disorders. The major accessory muscles of exhalation include the rectus abdominis, external oblique, internal oblique, and the transversus abdominis. Sternal retractions are the inward movement of intercostal spaces and are caused by conditions that impede inspiration. They may occur anywhere along the respiratory tract. These conditions are characterized by increased resistance or decreased compliance. These inspiratory barriers are overcome by more negative pressure generation during inspiration, resulting in an

inward movement of the intercostal spaces, suprasternal spaces, and subclavian spaces.

Paradoxical Breathing Paradoxical breathing occurs when chest movement

is the opposite of the normal chest motion. One common cause of paradoxical breathing is flail chest. A flail is the result of two or more rib fractures in two or more places, causing instability of the isolated piece of the chest wall. In this situation, the affected side moves inward on inspiration and outward during expiration. A flail chest causes a restrictive lung disorder because of rib instability, lung volume restriction, atelectasis, lung contusion, and possible pneumothorax. The chest and abdomen move in synchrony during the respiratory cycle. The paradoxical motion of the abdomen during inspiration indicates diaphragmatic weakness associated with paralysis. Paradoxical inward movement of the chest wall during inspiration indicates paralysis of the chest wall muscle, as may occur in high thoracic spine injury or low cervical spine injury.

Finger Clubbing Chronic hypoxia can lead to digital clubbing, where the fingers appear like a small club (Figure 1-3). Digital clubbing is due to chronic diseases such as bronchiectasis, congenital heart disease, cystic fibrosis, GI disease, liver disease, and lung tumors.

Chest Configuration Inspection of chest configuration is important to ­identifying abnormalities of the chest that impact on pulmonary mechanics and reveal information about the progression of lung disease. Barrel chest is a c­ ommon finding in many patients with obstructive lung disease

13

14

CHAPTER 1  Cardiopulmonary Assessment

(A)

(B)

(A)

(B)

FIGURE 1-4  Normal chest configuration (A) and a patient with an

increased anteroposterior diameter (B).

(C) FIGURE 1-3  Digital clubbing. Normal finger (A), mild digital clubbing

Data from Wilkins RL. Physical Examination of the Patient with Cardiopulmonary Disease. In: Wilkins R, Krider S, Sheldon R, eds. Clinical Assessment in Respiratory Care. 3rd ed. St. Louis: Mosby-Year Book; 1995: 47-77.

(B), and severe digital clubbing (C).

(e.g., emphysema) where the lateral ­diameter of a normal chest is twice the anteroposterior diameter. Figure 1-4 shows the comparison of a patient with a normal chest to a patient with a barrel chest. Other abnormalities of the thorax may cause restriction lung expansion and are restrictive lung diseases (Figure 1-5). One such abnormality is pectus excavatum, which is a sternum that is depressed and deviated like a funnel. Pectus carinatum is a chest that bows out at the sternum, similar to that of a pigeon. Scoliosis is a lateral curvature of the spine. Kyphosis is the forward curvature of the spine. Kyphoscoliosis is a combination of kyphosis and scoliosis. Lordosis causes posterior curvature of the spine.

when there is enough fluid in the interstitial space to cause an indentation in the skin when compressed under the fingertips.

Pedal Edema

Peripheral Skin Temperature

Edema is an excessive accumulation of fluid in the interstitial space. Chronic lung disease can cause pedal edema because of right heart failure or cor pulmonale. Chronic hypoxemia causes pulmonary vasoconstriction that increases the right heart workload to push the blood through the constricted vasculature. This results in right ventricular hypertrophy and decreased venous return to the right heart. The reduced blood return to the right heart increases venous hydrostatic pressure and fluid accumulates in the interstitial space of the ankles, causing pedal edema. The patient with left heart failure also often presents with pedal edema; and edema of the feet, legs, and arms is not uncommon in patients with multisystem organ failure.13 Pitting edema occurs

Palpation Palpation is the art of touching and feeling the surface of the body to assess the underlying tissue. For chest assessment, this involves touching the chest wall of a patient to find areas of tenderness or subcutaneous emphysema due to trauma, determine chest expansion, and assess for tactile fremitus. Palpation uses the fingertips, palms, or the ulnar part of the hand with light pressure. Table 1-13 shows a review of the elements of palpation.

Palpation of the patient’s feet and hands provides ­information about perfusion; cool extremities may indicate inadequate perfusion. When cardiac output and blood flow are not sufficient, compensatory vasoconstriction of the extremities shunts the blood to the vital organs. The peripheral vasoconstriction and reduced perfusion result in the loss of warmth in the extremities.

Capillary Refill Time Capillary refill time (CRT) is the amount of time re-

quired for the return of color after the application of blanching pressure to a distal capillary bed, and is used

Essential Elements of a Pulmonary Examination

(A) (B)

(C)

(D)

FIGURE 1-5  Abnormal chest configurations. Pectus excavatum (A), kyphosis (B), scoliosis (C), and pectus carinatum (D). (A) © Dr P. Marazzi/Science Source; (B) © Dr P. Marazzi/Science Source; (C) © Ralf Geithe/iStock/Getty Images; (D) Reproduced with permission from Hock, András. Minimal access treatment of pectus carinatum: a preliminary report. Pediatr Surg Int. 2009; 25(4):337–342 (Web. February 14, 2016; Figure 2, p. 340).

TABLE 1-13 Elements of Palpation Palpation

Reveals

Peripheral skin temperature

Perfusion to skin, decreased skin temperature due to decrease in cardiac output, ambient temperature, or poor circulation

Capillary refill time

Decrease in perfusion to finger may be due to a decrease in cardiac output or poor circulation

Tactile fremitus

Increase due to solidlike or liquid substances (e.g., atelectasis) Decrease due to excessive air (e.g., COPD)

Subcutaneous emphysema

Air under skin due to trauma, esophageal rupture, bronchial tube rupture

Chest expansion

Right or left lung expansion problem

to assess the adequacy of blood flow to the extremities.17 Capillary refill is assessed by pressing the fingernail and counting the number of seconds it takes for the color to return to the finger nail. When cardiac output is low, and perfusion to the extremities is inadequate, capillary refill is slow. Normal CRT is less than 3 seconds. However, ambient temperature and patient temperature have a profound effect on CRT. A quick and easy bedside test to perform, CRT is done at any place and under any conditions. Unfortunately, its results cannot be interpreted with any degree of confidence in the adult population.18

Tactile Fremitus Normal lungs transmit palpable vibrations to the chest wall. This is fremitus and requires the examiner’s hands to be placed on the chest wall to feel the vibrations that occur while a patient is speaking. The patient is asked to repeat the word “ninety-nine” or

15

16

CHAPTER 1  Cardiopulmonary Assessment “one-one-one,” while the examiner places the ulnar aspect of both hands firmly against either side of the posterior chest wall between the scapula and the spine. The hands are moved downward and laterally to assess the lower lobes. Sound waves move through gas, liquids, and solids. The movement of sound vibrations through a liquid and a solid are more effective than through gas (air). This is the basis for using tactile fremitus to assess the lungs. Some disease processes increase the transmission of sound and augment the intensity of the vibration felt. These disease processes include pneumonia (consolidation), pulmonary fibrosis, atelectasis, alveolar consolidation, pulmonary edema, and lung tumor. Other conditions diminish the transmission of sound and decrease the intensity of the vibrations. These disease processes include pneumothorax and hyperinflation (air trapping). Another reason for a decrease in tactile fremitus is obesity, overly muscular chest, and pleural effusion. These increase the distance between the chest wall and the air-filled lungs. It is important to note that if the area of consolidation or atelectasis is not in contact with an open airway, tactile fremitus decreases or is absent. This occurs with atelectasis caused by complete bronchial obstruction. Fremitus is relatively subtle and is difficult to note when the increase or decrease is bilateral. Tactile fremitus can be supportive evidence used in addition to all other elements of assessment.

Subcutaneous Emphysema Subcutaneous emphysema is the presence of air under the skin. The air may be present in subcutaneous tissues of the neck, chest, and face. This condition may be painful, and the tissues may swell. Subcutaneous emphysema may be detected by placing the stethoscope over the tissue and listening for crackling or popping sounds or by palpating bubbles as the examiner’s fingers move along the surface of the affected area. The possible causes of subcutaneous emphysema include chest trauma, rupture of the esophagus, a rupture in the bronchial tube, or as a result of invasive procedures such as intubation, bronchoscopy, and central line insertion.

fingertips are spread out across the lower chest wall. At the end of the full, deep breath, the practitioner should note the distance each thumb moves outward from the midline. Under normal conditions, each thumb moves equally (symmetrically) a distance of approximately 3–5 cm.

Percussion Percussion or tapping with a finger is used to evaluate the underlying lung tissue by the transmitted sounds. During percussion of the chest, the clinician firmly places the middle finger of the nondominant hand over the area to be evaluated. With the flip of the nondominant wrist, the tip of the dominant hand middle finger is used to strike the finger on the chest. Symmetrical and orderly chest percussion is essential to compare the sounds generated over the percussed areas of the chest (Figure 1-6). A normal air-filled lung creates a resonant sound on percussion. Resonance, or resonant percussion note, is the natural frequencies of vibration through normal air-filled lungs. Alterations in the lung tissue cause changes in the resonance heard during percussion.

Dull Percussion Note A dull percussion note heard over the areas of high density or areas with little or no air is due to pleural effusion, atelectasis, and pleural thickening. It is also heard over the liver and a tumor. A dull percussion note has a flat or soft, high frequency (high pitch) and short duration. When there is an increase in tissue density, the sound vibrations generated by percussion do not freely transmit through the lungs.

Hyperresonant Percussion Note A hyperresonant note is loud, has a high pitch, and is of long duration. This note is heard over the areas of low tissue density or areas with increased air. These areas occur in patients who have emphysema, pneumothorax,

Chest Wall Expansion The chest wall is palpated to determine if the lungs are expanding symmetrically. Lung disorders such as atelectasis, pneumothorax, pneumonia, lung resection, and right main stem intubation can cause asymmetrical chest expansion. To assess for asymmetrical expansion, the practitioner places the tips of each thumb on the patient’s posterior chest so that they are touching at approximately the eighth thoracic vertebra. The thumbs are placed after the patient exhales fully, before a full and deep breath. The palmar surface of the hand and

FIGURE 1-6  Percussion technique. © Jones & Bartlett Learning. Courtesy of MIEMSS.

Essential Elements of a Pulmonary Examination

Case Study: Dyspnea Associated with Septic Shock The respiratory therapist is called to evaluate a patient with symptoms of septic shock. The patient is complaining of SOB and elevated body temperature. His level of consciousness (LOC) has been deteriorating for the past few hours; he is alert but confused. Physical assessment of the patient reveals the following: Heart rate = 106 beats/minute ƒƒ RR = 26 breaths/minute ƒƒ BP = 84/62 mm Hg ƒƒ Auscultation = bibasilar fine crackles ƒƒ No pedal edema or JVD ƒƒ Extremities cool to touch with peripheral ƒƒ cyanosis Positive for central cyanosis ƒƒ Capillary refill = 5 seconds ƒƒ Briefly, explain the assessment parameters that may suggest this patient has hypoxia. Until the physician arrives at the hospital, what recommendations are appropriate for this patient? Case Review Assessment Septic shock or any type of shock could be detrimental to the patient if not treated promptly and appropriately. Shock is generally defined as the inability of the cardiovascular system to deliver adequate oxygen to the tissues. The objective data obtained from patient assessment indicate cardiopulmonary inefficiency to meet the body’s metabolic demand. The patient is in a hypermetabolic state because of the fever. This

an asthma exacerbation, or dynamic hyperinflation due to mechanical ventilation.

Auscultation of Breath Sounds Breath sounds are generated in the large airways because of high air flow in the trachea and large bronchi. The bulk flow of air and its velocity produce turbulence in the large airways, creating audible sounds. Gas movement in the alveoli is due to simple diffusion, not bulk flow. Therefore, there are no audible lung sounds produced in the alveoli. Listening to the breath sounds is the respiratory therapist’s most important physical assessment technique. Breath sounds provide valuable information about a patient’s lungs and their condition. Auscultation requires the use of a stethoscope and a quiet environment. The best position for the patient is sitting up. The anterior, posterior, and both lateral chest walls require breath sound assessment. Placing the stethoscope against bare skin eliminates distortion caused by

increases CO2 production and increases oxygen demand. Both the heart rate and the RR are increased to attempt to meet that high demand. The feeling of dyspnea is the patient’s perception of increased effort beyond normal to get air into his lungs. Auscultation revealed bibasilar fine crackles, which may be due to atelectasis. Cool extremities are a sign of compensation for hypotension due to vasoconstriction of superficial blood vessels, diverting the blood flow to the organs with high metabolic demand. A capillary refill of 5 seconds is indicative of poor peripheral perfusion. Cyanosis of the lips and mucous membrane indicates central cyanosis caused by tissue hypoxia. Low pulse pressure (PP) and hypoxia can account for the patient’s confusion by causing cerebral hypoxia. Lack of pedal edema and JVD may rule out right heart failure and could be the result of hypotension. Respiratory Therapist’s Recommendations The respiratory therapist recommends that the patient be started on oxygen therapy and monitored by pulse oximetry to maintain a saturation of greater than 92%. Vasopressor medications are indicated to increase the patient’s BP. It is imperative that hemodynamics be restored to ensure adequate oxygen delivery to the tissues. Continuous ECG monitoring is necessary to monitor for tachycardia and cardiac arrhythmias. This patient needs to be monitored continually until the physician arrives.

clothing. The tubing should not be in contact with or rub against any objects during auscultation. The sounds created by the tubing rubbing against objects may be erroneously interpreted as adventitious lung sounds. Auscultation of breath sounds must be symmetrical with a comparison of the same spot over each lung segment. At each location on the chest wall, the patient inhales slightly deeper than normal and exhales passively. The auscultation of breath sounds should begin at the base of the lungs over the posterior chest (Figure 1-7). There are four major characteristics of a breath sound that require assessment. The pitch is the physical property of vibrational frequency. The higher the frequency, the higher the pitch. Intensity, or amplitude, is the degree of change in pressure (positive or negative) during breathing and is directly proportional to the depth of breath, duration of inspiratory or expiratory sounds, and location of the sounds. Table 1-14 shows the characteristics of the normal breath sounds.

17

18

CHAPTER 1  Cardiopulmonary Assessment

10

9

7

8

6

5

3

4

2

1 11 14

(A) 18

15

(B)

19

20

12 22

21

13 23

16 17

24

26

(C)

25

(D)

FIGURE 1-7  Suggested sequence for systematic auscultation of the chest. For chest auscultation, always move from side to side (e.g., 1 to

2, 3 to 4, 5 to 6) to compare breath sounds on the left versus the right side. The suggested sequence for auscultation for a complete chest examination is numbered. The respiratory care clinician should listen to breath sounds on inspiration and expiration and move in sequence from position 1 through 25.

TABLE 1-14 Normal Breath Sound Characteristics Breath Sound

Pitch

Intensity

Duration

Location

Vesicular

Low

Soft

Throughout inspiration until early in exhalation

Most lung fields

Bronchovesicular

Medium

Moderate

Throughout inspiration and expiration

Main bronchus area and upper right posterior lung field

Tracheal

High

Loud

Throughout inspiration and expiration

Trachea

Essential Elements of a Pulmonary Examination

Normal Breath Sounds Tracheal breath sounds, also called bronchial breath

sounds, are heard over the trachea and are high pitched with loud intensity as a result of turbulence created by the bulk flow in the trachea. The inspiratory and expiratory tracheal breath sounds are equal in length. If this breath sound occurs over lung fields, it is indicative of consolidation. Bronchovesicular breath sounds are heard anteriorly over the upper part of the sternum between the first and second intercostal spaces. This is a combination of tracheal breath sounds and vesicular breath sounds. If this sound occurs over lung fields, it is indicative of consolidation. Vesicular breath sounds, low pitched with a soft intensity, are heard over the lung periphery (parenchyma) where alveoli are located. The inspiratory phase is longer than the expiratory phase. The differences in these breath sounds are explained by the role that healthy lung tissue plays in “filtering” or muffling the harsh sounds produced by turbulent flow in the trachea and large airways.13 Figure 1-8 shows an example of a normal versus abnormal (adventitious) breath sound heard during auscultation.

Adventitious Breath Sounds In addition to normal lung sounds, other sounds may be produced in the lung when the underlying tissue is abnormal. Different lung pathologies produce sounds that do not occur normally; these lung sounds are adventitious breath sounds. Adventitious lung sounds are either continuous or discontinuous. The continuous sound maintains a uniform pattern for at least one-tenth of a second.13 The discontinuous sound does not hold that pattern.13 Crackles or rales are discontinuous (becoming stronger and weaker during the respiratory cycle) ILL

Rhonchi: coarse, low-pitched; may clear with cough Wheeze: whistling, high-pitched Bronchial: coarse, loud; heard with consolidation Rub: scratchy, high-pitched Crackles: fine crackling, high-pitched FIGURE 1-8  Abnormal and normal breath sounds.

adventitious breath sounds. Crackles are brief and explosive, and are usually heard during inspiration (sometimes during late inspiration). Depending on their site of origin, crackles have different qualities. They are often divided into fine, medium, and coarse. Fine crackles occur when terminal airways and alveoli pop open during a deep breath when the inspiratory effort is sufficient enough to overcome the forces that collapsed the airways or the alveoli (atelectasis). Medium crackles occur when air is passing through fluid-containing bronchi. Coarse crackles are present in CHF when fluid accumulates in the interstitial space between the capillaries and alveoli. In the initial stage of CHF, coarse crackles are heard in the base of the lungs. As CHF worsens, crackles ascend higher up the airways. Medium and coarse crackles are also present in pneumonia over the involved lobe. In general, the common causes of crackles include atelectasis, pulmonary edema, interstitial lung disease, acute respiratory distress syndrome, and respiratory infections. Rhonchi are deep rumbling sounds that are continuous and more pronounced during expiration. Rhonchi occur because of air passing through partially obstructed always or a tumor. Low-pitched rhonchi occur because of the presence of thick secretions in the larger airways. These rumbling rhonchi may be palpable through the chest wall. The Latin word rhonchus means wheeze; occasionally, rhonchi are called sonorous wheezes. The term wheeze is used to describe the musical lung sounds from the lungs with intrathoracic airway obstruction. Wheezes occur because of rapid airflow through narrowed (obstructed) airways. The wheeze is indicative of increased airway resistance and work of breathing under conditions such as asthma and CHF. Wheezes are usually high pitched and most commonly heard during expiration. As airways narrow, wheezes may be heard on expiration as well as on inspiration. WELL

Bronchial: coarse, loud Bronchovesicular: combination bronchial and vesicular; normal in some areas Vesicular: high-pitched, breezy

19

20

CHAPTER 1  Cardiopulmonary Assessment Airway diameter reduction and wheezes are indicative of bronchospasm, bronchitis, lung tumors, foreign body obstruction, and pulmonary edema. Stridor is produced by airflow with high velocity through a narrowed larynx and trachea. The diameter of larynx and trachea are decreased because of infections such as croup or epiglottitis or from postextubation edema as a result of tissue injury. Stridor is a life-threatening sign because ventilation is compromised in patients with stridor. Close monitoring is imperative, and an emergency intubation or tracheostomy may be needed. Treatment for the causes of stridor includes cool humidity or aerosolized racemic epinephrine, depending on its cause. Grunting is a lung sound heard in newborns with respiratory distress. It occurs when the newborn exhales against a partially closed glottis in an attempt to maintain lung volumes and prevent alveolar collapse. Grunting may be loud enough to hear without a stethoscope. Grunting improves gas exchange by increasing the functional residual capacity. When pleural membranes become inflamed and rub against each other, a creaking or grating sound is produced and called a pleural friction rub. A pleural friction rub is localized and limited to the areas of pleural irritation, and may be intermittent. Pleural rubs usually occur in patients with pneumonia,

pulmonary fibrosis, pulmonary embolism, pleural effusion, or post thoracic surgery. A decrease in airflow into the lungs will cause diminished breath sounds. Little or no air flow will cause an absence in the production of breath sounds. This emergent situation occurs because of atelectasis, pneumothorax, consolidation, or severe asthma exacerbation. Voice resonance, like breath sounds, reflects changes in lung density and airway patency and can help identify the underlying disease. Voice resonance increases with consolidation of the lung and decreases in lung collapse.6 Voice sounds are normally muffled when auscultated during patient speech. When the practitioner auscultates over an area of suspected consolidation and has the patient say ninety-nine, if heard clearly it is bronchophony.1 Similarly, egophony is elicited when the patient is asked to say the letter e. Over normal lung fields, the e would sound like e. Over areas of consolidation, the letter e sounds like the annunciation of the letter a. This “e to a” phenomenon occurs over areas of consolidation.1 Whispered pectoriloquy refers to a distinct increase in transmission of vocal sounds associated with early pneumonia, pulmonary infarction, or atelectasis.13 With this voice sound, the whispered numbers “one, two, three” are heard clearly through the stethoscope.

Case Study: Postoperative Atelectasis The respiratory therapist is called in to evaluate a patient who is postoperative 3 days for upper abdominal surgery. She is afebrile, alert, and oriented, but complains of SOB. She is 62 years old, 5 feet tall, and weighs 190 lb. Her respiratory pattern is rapid at 36 beats/minute and shallow. Heart rate is 112 beats/ minute and regular. The patient indicated that her SOB has increased for the past few hours and gets worse with any activity. Auscultation reveals diminished breath sounds with fine, late inspiratory crackles. The review of other body systems was unremarkable. Issue: What is the most likely explanation of the patient’s dyspnea and inspiratory crackles? Case Review Assessment Pulmonary complications are not uncommon following upper abdominal surgery. There are many factors that contributed to this patient’s postoperative dyspnea. 1. The surgical operation was in proximity to the diaphragm. The diaphragm is the major muscle of inspiration and any operation that might limit its contraction and relaxation will compromise the patient’s tidal volume, as evident by an increase

in RR and shallow breathing. The increase in RR is proportional to the degree of volume loss. 2. The late inspiratory crackles are caused by the sudden opening of peripheral airways during inspiration. 3. The patient weight is another contributing factor to her inability to breathe deep; her estimated ideal body is about 105 lb. These findings suggest atelectasis and loss of lung volume as the cause of dyspnea. Atelectasis causes arterial desaturation and hence low arterial oxygen content. The patient’s inability to provide the increase in oxygen demand leads to worsening of dyspnea on exertion. Respiratory Therapist’s Recommendations There may be other reasons for the patient’s dyspnea besides postoperative atelectasis. CHF and pulmonary embolism are also concerns that need to be ruled out. The respiratory therapist recommends a chest radiograph and lung expansion therapy if atelectasis is confirmed.

Essential Elements of the Cardiac Examination

KNOWLEDGE CHECK QUESTIONS 1. True or False: Restrictive lung disease causes a barrel chest. 2. True or False: Bronchial breath sounds indicate lung consolidation.

Essential Elements of the Cardiac Examination The cardiac examination is a systematic examination that begins with the clinician’s first clinical impression, through observation or the view from the door. A closer look at the patient involves the inspection of the periphery as well as the chest. This inspection requires visualization of the patient’s chest. Care must be taken to ensure privacy and comfort during the cardiac examination. Chest palpation identifies the heart’s point of maximal impulse (PMI) and auscultation over the heart identifies abnormal heart sounds.

fifth intercostal space and is due to left ventricular contraction (systolic thrust). If the PMI is visible, its location and size need to be noted.

Palpation Because the apical impulse is not always visible, the clinician can palpate the PMI (Figure 1-9). The PMI may shift to the right or left with shifts in the mediastinum. Patients with COPD (emphysema) and air trapping with flat diaphragms may have the PMI shifted toward the epigastric area. Also, the left ventricular hypertrophy may cause an enlarged PMI.

Auscultation Auscultation of the heart sounds provides valuable information that is significant in evaluating the critically ill patient. There are five auscultatory sites to assess during a cardiac examination (Figure 1-10). Normal heart sounds are primarily created by the closure of mitral, tricuspid, pulmonic, and aortic valves during the cardiac cycle (systole and diastole). The normal heart sounds are S1 and S2 (the “lub-dub” sound).

Observation

Normal Heart Sounds

Examination of a patient’s cardiovascular system begins, in earnest, with the observation of the patient, vital sign assessment, observation of JVD, finger assessment for clubbing, and ankle assessment for pedal edema.

The first heart sound, S1, is produced when the mitral and tricuspid valves snap shut simultaneously at the beginning of systole. The first heart sound is the “lub.” Normally, S1 is a single sound; any delay in right ventricular systole may cause S1 to split into its two component sounds. Right bundle branch block (RBBB) is the most common cause of S1 splitting. The second heart sound, S2, is caused by the closure of the aortic and pulmonic valves during ventricular relaxation (diastole). The second heart sound is the “dub.” This sound is heard best at the aortic and pulmonic listening positions. Splitting of S2 occurs when pulmonic and aortic valves do not close simultaneously. A narrow splitting of S2 that occurs during inspiration

Jugular Venous Distension The primary visual inspection of cardiac assessment involves observation of the right internal JVP. Fluctuations in the right jugular vein reflect pressure changes in the right atrium and provide an indication of right heart hemodynamics. Distension of the right jugular vein suggests increased volume in the right ventricle and often suggests right ventricular failure. Normal jugular venous oscillation should not exceed 3 cm above the sternal angle (angle of Louis; Figure 1-1).

Inspection With the patient in the supine position and the head elevated to 30°, inspection of the anterior chest wall is done to check for scars, an implanted pacemaker, and visible pulsations. Be sure to explain what you are doing and why before beginning. Expose the minimum amount of bare skin necessary. Ask for the patient’s assistance to raise and cover the breast area if the patient is a female. The patient’s age, size of the chest, and state of health influence this inspection. Obesity, large breasts, and a muscular chest can make the precordial examination more difficult. Apical pulsation or the point of maximal impulse occurs because the apex of the heart bumps against the chest wall with each heartbeat.19 The PMI occurs in the midclavicular line in the

FIGURE 1-9  Palpation of the apical pulse. © Jones & Bartlett Learning. Photographed by Christine Myaskovsky.

21

22

CHAPTER 1  Cardiopulmonary Assessment

Aortic valve

Pulmonic valve Erb’s point Tricuspid valve Mitral valve, PMI

FIGURE 1-10  Use a systematic approach to auscultating heart sounds. Listen to each area for the S1 and S2. The sound of the aortic valve

occurs over the “aortic area.” The pulmonic valve closure occurs over the “pulmonic area.” Erb’s point is a common listening area, which lies halfway between the apex and the base of the heart. The mitral valve is heard over the PMI or the “mitral area.”

TABLE 1-15 Normal Heart Sounds

BOX 1-4 Steps to Cardiac Auscultation

Sound Name

S1

S2

Sound heard

“Lub”

“Dub”

Cause

Closure of mitral and tricuspid valves

Closure of aortic and pulmonary valves

Timing

Beginning of systole or ventricular contraction

Beginning of diastole or ventricular filling

Best heard over

Apex of heart (PMI or mitral area)

Base of heart (aortic and pulmonic areas)

is a physiologic phenomenon and is the result of a decrease in intrathoracic pressure and increased venous return to the right side of the heart. A significant delay of pulmonic and aortic valve closure will produce a wide splitting of S2 and is indicative of pulmonary hypertension, RBBB, pulmonary embolism, and right-sided heart failure. Table 1-15 summarizes the normal heart sounds. Listening to cardiac sounds takes concentration and practice.19 See Box 1-4 for an outline of the steps to the cardiac auscultation. Extraneous noises need to be reduced, and the stethoscope must be placed directly on the skin. If the heart sounds are difficult to hear, the practitioner can ask the patient to change position. Sitting upright and leaning forward or lying down in the left decubitus position brings the heart closer to the chest wall.

Abnormal Heart Sounds Extra heart sounds, S3, and S4, are generated by atypical blood flow mechanisms. These sounds, if present, are heard over the mitral area. Both S3 and S4 occur during diastolic filling and are due to blood striking the left

1. Begin with the aortic area, located along the right sternal border. Palpating for the right second intercostal space along the right sternal border will ensure the appropriate stethoscope location. 2. Next, move the stethoscope directly toward the patient’s left sternal border at the left second intercostal space. This is clinically called the pulmonic area or left upper sternal border. 3. Moving down the left sternal border, next auscultate the tricuspid area. This area is at the left lower sternal border at the left fourth intercostal space. 4. The final auscultatory site is the mitral area, which is at the apex of the heart. The mitral area is anatomically at the fifth intercostal space in the midclavicular line. To auscultate the mitral area, use the bell of the stethoscope and have the patient lie in the left lateral decubitus position. ventricle.13 These rhythms are commonly called gallops because of their resemblance to the sound of a horse galloping.1 The S3 heart sound is often a sign of systolic heart failure. However, it can be a normal finding in children, pregnant females, and well-trained athletes. The S4 heart sound is always abnormal, and goes by the name “atrial gallop.” The S4 sound occurs during active left ventricular filling when atrial contraction forces blood into a noncompliant left ventricle. The S4 sound is indicative of diastolic heart failure and may also occur with atrial fibrillation. Table 1-16 summarizes the abnormal heart sounds.

Neurologic Assessment

TABLE 1-16 Abnormal Heart Sounds Sound Name

BOX 1-5 Timing and Grades of Heart Murmurs

S3

S4

Sound heard

“Bub” in “lub-du-bub”

First “dub” in “dub-lub-dub”

Cause

Can be normal in healthy young athletes Distended or floppy left ventricle Systolic dysfunction Congestive heart failure

Atrial contraction or atrial kick Noncompliant left ventricle Diastolic heart failure Atrial fibrillation Active myocardial ischemia

Timing

After S2

Late diastole, just before S1

Best heard over

Apex of heart with stethoscope bell with patient in left lateral decubitus position

Apex of heart with stethoscope bell with patient in left lateral decubitus position

Abnormal heart sounds occur from turbulent blood flow within the heart. These “whooshing” sounds are heart murmurs. Murmurs occur when blood travels backward through a leaky valve (regurgitation), is forced through an abnormally tight area (stenosis), or is forced through a congenital anomaly between chambers. Causes of systolic heart murmurs include aortic stenosis, pulmonic stenosis, atrial septal defect, mitral regurgitation, tricuspid regurgitation, and ventricular septal defect. Causes of diastolic murmurs include aortic regurgitation, pulmonic regurgitation, mitral stenosis, and tricuspid stenosis. The description of a heart murmur uses timing in the cardiac cycle, intensity, location, quality, pitch, configuration, and the response to specific maneuvers. Using those features will accurately characterize the nature of a murmur.20 The timing of murmurs is early, middle, or late systolic—that is, occurring between S1 and S2. Others are diastolic, coming between S2 and S1.1 Furthermore, systolic and diastolic murmurs are divided according to their duration within the cardiac cycle.20 Systolic murmurs that are present throughout all of systole are holosystolic. Systolic murmurs can also be mid-systolic, early systolic, and mid-to-late systolic. Diastolic murmurs can be early diastolic, mid-diastolic, and late diastolic. The intensity of a murmur is also classified by the intensity on a scale of 1 through 6. Box 1-5 provides the grading system for intensity; the higher the grade, the louder the intensity. The location where the murmur is loudest helps identify the origin of the murmur. For example, the murmur of aortic stenosis is loudest over the aortic area, and the murmur of pulmonary stenosis is loudest over the pulmonary area (Figure 1-10).

Grade 1: Very faint murmur only appreciated by an expert in optimum conditions. Grade 2: Faint murmur recognized by nonexpert in optimum conditions. Grade 3: Loud murmur without an accompanying thrill.* Grade 4: Loud murmur with an accompanying thrill. Grade 5: Loud murmur heard with stethoscope partially off the chest. Grade 6: Loud murmur heard with stethoscope off the chest. *A "thrill" is a tremor or vibration felt upon palpation of the chest wall.

The quality of a murmur is harsh, blowing, musical, or squeaky. The pitch is either low, medium, or high. A high-pitched murmur is due to a large pressure gradient across a pathologic lesion. A change in the intensity of the murmur throughout the cardiac cycle is the configuration of the murmur. Configuration can be crescendo (increases progressively in intensity from start to finish), decrescendo (decreases progressively in intensity from start to finish), crescendo-decrescendo (increases then decreases in intensity), diamond-shaped decrescendocrescendo (decreases then increases in intensity), plateau (constant intensity), and rectangular shaped (holosystolic or pansystolic).20 Lastly, some murmurs respond to changes in position as a result of changes in preload, afterload, and chamber size that affect the characteristic of a murmur. Many murmurs are classified as functional, innocent, or physiologic, meaning that they are clinically insignificant.1 Others are significant in that they suggest a progressive pathologic process that may eventually require surgical intervention.1

KNOWLEDGE CHECK QUESTIONS 1. True or False: Left ventricular hypertrophy may cause the point of maximum impulse to shift to the epigastric area. 2. True or False: The S3 heart sound is commonly normal in athletes and pregnant women.

Neurologic Assessment Nervous system injuries often affect a patient’s respiratory function. Familiarity with the basic components of the neurologic examination and common neurologic

23

24

CHAPTER 1  Cardiopulmonary Assessment abnormalities are essential to the respiratory therapist. The respiratory therapist needs to be able to assess a patient’s LOC using the appropriate terms and assess and understand the commonly used neurologic scoring systems, such as the GCS, Ramsay Sedation Scale, the Richmond Agitation–Sedation Scale, and the Confusion Assessment Method for Assessing Delirium in the Intensive Care Unit. Other important aspects of the neurologic assessment include posturing and pupillary response.

Level of Consciousness The most sensitive indicator of neurologic change is consciousness, which is the state of general awareness of oneself and the environment. It is difficult to measure consciousness directly. However, observation of a patient’s response to certain stimuli supplies an estimation of consciousness. Assessment of LOC begins at the initial patient encounter. A patient with intact and normal functioning CNS will be awake, interacting, and communicating with others. If asleep, the patient can be easily aroused to an awake and alert state. If the patient does not respond to verbal stimuli but moves spontaneously in a purposeful manner, the patient is localizing. Localizing is purposeful and intentional movement intended to remove the stimulus. The terms in Table 1-17 are used to describe deviations from the normal LOC.

Glasgow Coma Scale When a patient experiences an alteration in the LOC because of trauma or some other hypoxic or metabolic event, the Glasgow Coma Scale (GCS, Table 1-18) is TABLE 1-17 Terms to Describe Levels of Consciousness Term

Description

Coma (comatose)

The patient does not respond to any stimuli, even painful stimuli. The patient is unconscious.

Confusion (confused)

Delirium (delirious)

Patient has difficulty understanding directions. The patient is not oriented to person, place, time, or situation.

commonly used.1 This scale decreases the subjectivity of responses by assessing and quantifying the patient’s neurologic impairment. The GCS is used to evaluate the best motor response, best verbal response, and eye opening. The scale goes from a low of 3 to a maximum of 15. A score of 3 points is consistent with a deep coma or brain death. A score of 15 points indicates full consciousness (Table 1-18).

Ramsay Sedation Scale In patients who are critically ill, sedation and decreased LOC are often pharmacologically induced.1 In delivering prescribed sedation, the use of valid sedation assessment tools promotes safe practice, and the repeated use of sedation scores helps ensure that documentation is kept up to date and that the cumulative effects of sedation on patients’ cognitive states are minimized.21 This scale has two defined groups of scores: those of 1, 2, and 3 are given in assessing degrees of wakefulness, and those of 4, 5, and 6 are given in assessing degrees of sleep (Table 1-19). The use of this type of scale can prevent over- and undersedation of patients who are acutely or critically ill.21 TABLE 1-18 Glasgow Coma Scale Observation

Score

Eye Opening Response Spontaneously

4

In response to voice

3

In response to pain

2

None

1

Verbal Response Oriented response

5

Confused response

4

Inappropriate words

3

Incomprehensible words

2

None

1

The patient is confused, restless, agitated, incoherent, and is often having hallucinations.

Motor Response Obeys commands

6

Lethargy (lethargic)

The patient is drowsy, but can be aroused.

Localizes

5

Obtunded

The patient is difficult to arouse but responds appropriately.

Withdraws

4

Flexes (decorticate)

3

Extends (decerebrate)

2

None

1

Semi-coma (semi-comatose)

Patient is unconscious but responds to pain.

Stupor (stuporous)

Patient has reduced responsiveness when attempts are made to arouse.

Data from Center for Disease Control: Glascow Coma Score. Last updated May, 2003. http://www.bt.cdc.gov/massacasualties/pdf/glasgow-coma-scale.pdf

Neurologic Assessment

Richmond Agitation–Sedation Scale Agitated behavior frequently occurs in patients in the intensive care unit (ICU). Structured assessment of sedation and agitation is useful to titrate sedative TABLE 1-19 Ramsay Sedation Scale Observation

Score

Patient is anxious and agitated, restless, or both

1

Patient is cooperative, oriented, and tranquil

2

Patient responds to commands only

3

Patient exhibits brisk response to light glabellar tap or loud auditory stimulus

4

Patient exhibits a sluggish response to light glabellar tap or loud auditory stimulus

5

Patient exhibits no response

6

Reproduced with permission from Dawson R, Fintel N, Nairn S. Sedation assessment using the Ramsay scale. Emergency Nurse. 2010;18(3):19 (Table 1, page 19)

medications and to evaluate agitated behavior.22 RASS is a 10-point scale, with four levels of anxiety or agitation (+1 to +4 [combative]), one level to denote a calm and alert state (0), and five levels of sedation (−1 to −5) culminating in unarousable (−5)22 (Table 1-20).

Confusion Assessment Method for Assessing Delirium in the Intensive Care Unit Conventional treatment of mechanically ventilated patients in the ICU has included deep sedation and, in some cases, muscle relaxation.23 Prolonged ICU and hospital stays are associated with an increase in the diagnosis of delirium.23,24 The diagnosis of delirium is particularly problematic in intubated patients because of problems of communication and the common use of sedative and analgesic drugs. Recent guidelines recommend that all adult patients in the ICU need regular assessment for delirium.25 One of the methods recommended is the CAM-ICU monitoring tool (Figure 1-11).

TABLE 1-20 Richmond Agitation–Sedation Scale22 Score

Term

Description

+4

Combative

Overtly combative, violent, immediate danger to staff

+3

Very agitated

Pulls on or removes tube(s) or catheter(s) or aggressive toward staff

+2

Agitated

Frequent nonpurposeful movement or patient–ventilator dyssynchrony

+1

Restless

Anxious or apprehensive, but movements not aggressive or vigorous

0

Alert and calm

−1

Drowsy

Not fully alert, but has sustained (>10 seconds) awakening, with eye contact, to voice

−2

Light sedation

Briefly (100 beats/minute. 2. True or False: Decreased sympathetic tone and increased vagal tone lead to ST. 3. True or False: The fast-conducting pathway in AVNRT has a rapid conduction rate but a slow refractory time. 4. True or False: All accessory pathways in AVRT have the same rates of conduction and refractory periods. 5. True or False: AF has an atrial depolarization rate of 160–180 beats/minute. 6. True or False: The most common conduction ratio in atrial flutter is 2:1. 7. True or False: Mobitz I or Wenckebach has a progressive delay after each P wave until there is a dropped beat. 8. True or False: Mobitz II blocks are more likely to progress to a complete heart block.

Chapter Summary The heart has electrical and mechanical activity. Before the mechanical action can happen, there must be electrical activity. This electrical activity is known as an action potential and is caused by potassium, sodium, calcium, and chloride. The action potential has five phases. Phase 1 is depolarization, Phase 4 is resting, and the other three phases are repolarization. The two types of cardiac cells are the pacemaker cells and the contractile cells. The native primary pacemaker of the heart is the SA node, and it will pace the heart at 60–100 beats/ minute. When the heart depolarizes and repolarizes, the heart is in NSR; when it does not, there will be an arrhythmia. Some of the arrhythmias can be life threatening and require immediate treatment.

387

388

CHAPTER 14  Cardiac Arrhythmias The life-threatening arrhythmias are VF, VTach, PEA, and asystole. Others arrhythmias are not immediately life threatening but need to be treated to prevent them from causing a problem or becoming life threatening. These arrhythmias are ST, AF, AV nodal re-entry tachycardia, AV re-entry tachycardia, firstdegree heart block, second-degree heart block Type I, second-degree heart block Type II, and third-degree heart block. Etiologies/risk factors for arrhythmias are age, CAD, inflammation, infections, heart surgery, valve problems, valve replacement, smoking, hypoxia, hyperlipidemia, cardiomyopathies, hypertension, obesity, medication, illicit drug use, and/or MI. The prevalence and incidence of these arrhythmias range from 100,000 per year for VF to 2.7–6.1 million for AF. The symptoms for these arrhythmias can be asymptomatic, light headedness, syncope, palpitations, chest pain, dyspnea, and/or tachyarrhythmia. These arrhythmias and their etiologies are diagnosed with a 12-lead ECG, echocardiogram, blood tests, EPSs, stress tests, nuclear studies, ambulatory cardiac monitoring, and/or heart catheterizations. The treatment of these arrhythmias can be medications, pacemaker or defibrillator implantation, RFA, monitoring, and/or coronary angioplasty. The complications from these arrhythmias can be death, developing a more serious arrhythmia, MI, blood clots, stroke, hemodynamic compromise, and/or CHF.

Key Points 1. The heart has to have an action potential to have a contraction. 2. Ions are responsible for the action potential. 3. Anything that can cause an electrolyte imbalance or electrical conduction problem may lead to an arrhythmia. 4. Some arrhythmias can be life threatening if not treated immediately. 5. Some arrhythmias may become life threatening if not treated appropriately and promptly. 6. The prevalence of some arrhythmias is 2.7–6.1 million per year. 7. Causes of arrhythmias can range from age to MIs. 8. Noninvasive and invasive tests are used to diagnose arrhythmias. 9. Treatment can be from monitoring the patient to coronary angioplasty. 10. Symptoms can be from none to chest pain to death. 11. Complications can range from death to blood clots. 12. Prognosis will depend on each of the risk factors of the individuals.

Chapter Questions 1. The electrolytes used by the heart muscle include _______. a. sodium b. chloride c. calcium d. all of the above 2. The resting voltage of a contractile myocardial cell is ________________. a. −90 mV b. −70 mV c. +30 mV d. −25 mV 3. The primary pacemaker of the heart is the ________________. a. bundle branch b. bundle of Kent c. SA node d. Atrioventricular (AV) node 4. How many phases are there to the action potential? a. 2 b. 3 c. 4 d. 5 5. Pacemaker cells have automaticity. In which phase does the calcium slowly move into the cells? a. 5 b. 4 c. 2 d. 0 6. Of the problems listed below, which one is a cause for ventricular fibrillation (VF)? a. Hypertension b. Low cholesterol c. Hypotension d. Sinus tachycardia (ST) 7. Which of the following has an increased risk for VF? a. Short QRS duration b. Myocardial infarction c. Wide R-to-R interval d. Prolonged PR interval 8. Which risk factors listed below will cause ventricular tachycardia (VTach)? a. Cardiomyopathy b. Heart failure c. Cocaine use d. All of the above 9. Which of the arrhythmias listed below is considered a supraventricular tachycardia? a. Normal sinus rhythm b. VTach c. Atrial fibrillation (AF) d. Junctional escape

References 10. Which of the conditions listed below is a cause of ST? a. Hypervolemia b. Hyperthyroidism c. Hyperglycemia d. Tobacco use 11. What is the major concern in patients with AF? a. Thrombus formation b. Reduced cardiac output c. Decreased preload d. Decreased afterload 12. The classifications of AF include which of the following? a. Acute AF b. Paroxysmal AF c. Persistent AF d. All of the above 13. AV re-entry tachycardia (AVRT) is a result of an accessory pathway, which develops in what part of the cardiac anatomy? a. Intraventricular septum b. Intra-atrial septum c. Atrioventricular septum d. AV node and ventricles 14. How many accessory pathways are there that lead from the right atrium to the AV node in AV nodal re-entry tachycardia? a. 3 b. 2 c. 5 d. 4 15. The most common site for a first-degree heart block is in which part of the heart? a. Bundle branches b. Bundle of His c. Purkinje fibers d. AV node 16. What is the contributing factor that will initiate AVRT? a. Premature ventricular contraction b. Premature atrial contraction c. ST d. VF 17. What device can be implanted to treat VF? a. Implantable cardioverter defibrillator b. Dual-chamber pacemaker c. Biventricular pacemaker d. None of the above 18. Which patient population has a higher risk of developing second-degree AV blocks? a. Young adults b. Women c. Highly trained athletes d. Children

19. Treatment for AF includes which of the following? a. Biventricular pacemaker b. Pulmonary vein isolation c. Defibrillation d. Implantable cardioverter defibrillator 20. The first-line diagnostic tool used to identify a third-degree AV block is ______________________. a. blood work b. heart catheterization c. electrocardiography d. electrophysiology studies

References 1. Garcia T, Miller G. Arrhythmia Recognition. Sudbury, MA: Jones and Bartlett Publishers; 2004. 2. Abnormal Heart Rhythms (Arrhythmias). WebMD. 2016. http:// www.webmd.com/heart-disease/guide/heart-disease-abnormal -heart-rhythm. Accessed September 3, 2015. 3. ACLS Provider Manual Supplementary Material. 1st ed. Dallas, TX: American Heart Association; 2012. 4. Klabunde R. CV physiology: sinoatrial node action potentials. 2015. http://cvphysiology.com/Arrhythmias/A004.htm. Accessed September 3, 2015. 5. Goyal S. Ventricular fibrillation: background, pathophysiology, etiology. 2014. http://emedicine.medscape.com/article/158712 -overview. Accessed March 24, 2018. 6. Mayo Clinic Staff. Ventricular Fibrillation Symptoms—Mayo Clinic. 2017. http://www.mayoclinic.org/diseases-conditions /ventricular-fibrillation/basics/symptoms/con-20034473. Accessed March 24, 2018. 7. Conover MD. Understanding Electrocardiography. St Louis, MO: Mosby; 2002. 8. Ventricular Fibrillation. Information about VF | Patient. 2014. http:// patient.info/doctor/ventricular-fibrillation. Accessed March 24, 2018. 9. Compton S. Ventricular Tachycardia: Practice Essentials, Background, Pathophysiology. 2017. http://emedicine.medscape.com /article/159075-overview. Accessed March 24, 2018. 10. Prust M, Stevenson W, Lilly L. Clinical aspects of cardiac arrhythmias. In: Lilly L, ed. Pathophysiology of Heart Disease. 6th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2016: 287–309. 11. Akdeniz C, Ozyilmaz I, Saygi M, Ergul Y, Tuzcu V. Idiopathic ventricular arrhythmias detected by an implantable loop recorder in a child with exercise-induced syncope. Tex Heart Inst J. 2013;40(3):347–349. 12. Baher A, Valderrabano M. Management of ventricular tachycardia in heart failure. Methodist DeBakey Cardiovasc J. 2013;9(1):20–25. doi:10.14797/mdcj-9-1-20. 13. Shah S. Pulseless Electrical Activity: Background, Etiology, Epide­ miology. 2017. http://emedicine.medscape.com/article/161080 -overview. Accessed March 25, 2018. 14. Littmann L, Bustin D, Haley M. A simplified and structured teaching tool for the evaluation and management of pulseless electrical activity. Med Princ Pract. 2014;23(1):1–6. doi:10.1159 /000354195. 15. Advanced Cardiovascular Life Support. Dallas, TX: American Heart Association; 2015. 16. Nadkarni VM, Larkin GL, Peberdy MA, et al. First documented rhythm and clinical outcome from in-hospital cardiac arrest among children and adults. JAMA. 2006;295(1):50. doi:10.1001/jama.295.1.50.

389

390

CHAPTER 14  Cardiac Arrhythmias 17. Meaney P, Nadkarni V, Kern K, Indik J, Halperin H, Berg R. Rhythms and outcomes of adult in-hospital cardiac arrest. Crit Care Med. 2010;38(1):101–108. doi:10.1097/ccm.0b013e3181b43282. 18. Shah SN. Asystole. 2015. http://emedicine.medscape.com /article/757257-overview. Accessed March 25, 2018. 19. Engdahl J, Bång A, Lindqvist J, Herlitz J. Can we define patients with no and those with some chance of survival when found in asystole out of hospital? Am J Cardiol. 2000;86(6):610–614. doi:10.1016 /s0002-9149(00)01037-7. 20. Lauro J. Dysrhythmias. In: Aghababian R, ed. Essentials of Emergency Medicine. 2nd ed. Sudbury, MA: Jones & Bartlett Learning; 2011:138–153. 21. Testori C, Sterz F, Behringer W, et al. Mild therapeutic hypothermia is associated with favorable outcome in patients after cardiac arrest with non-shockable rhythms. Resuscitation. 2011;82(9):1162–1167. doi:10.1016/j.resuscitation.2011.05.022. 22. Orejarena LA, Vidaillet H Jr, DeStefano F, et al. Paroxysmal supraventricular tachycardia in the general population. J Am Coll Cardiol. 1998;31(1):150–157. 23. Olshansky B, Chung Mk, Pogwizd SM, Goldschlager N. Arrhythmia Essentials. Sunbury, MA: Jones & Bartlett Learning; 2012. 24. Hottigoudar R, Gopinathannair R. ‘Inappropriate’ sinus tachycardia: does the 100 beats per min cut-off matter? Future Cardiol. 2013;9(2):273–288. doi:10.2217/fca.13.5. 25. Wesley K. Huszar’s Basic Dysrhythmias and Acute Coronary Syndromes: Interpretation and Management. St. Louis, MO: Elsevier; 2011. 26. Mitchell LB. Atrial Fibrillation. Merck Manuals Professional Edition. 2018. https://www.merckmanuals.com/professional /cardiovascular-disorders/arrhythmias-and-conduction-disorders /atrial-fibrillation-af. Accessed March 24, 2018. 27. Helton M. Diagnosis and management of common types of supraventricular tachycardia. Am Fam Physician. 2015;92(9):793–800. 28. Gugneja M. Paroxysmal Supraventricular Tachycardia. 2017. http:// emedicine.medscape.com/article/156670-overview#a6. Accessed March 25, 2018. 29. Ellis C. Wolff-Parkinson-White Syndrome: Practice Essentials, Background, Pathophysiology. 2017. http://emedicine.medscape .com/article/159222-overview#a1. Accessed March 24, 2018. 30. Alaeddini J. First-Degree Atrioventricular Block: Background, Pathophysiology, Etiology. 2015. http://emedicine.medscape.com /article/161829-overview. Accessed March 24, 2018. 31. Center for Disease Control and Prevention. Atrial Fibrillation Fact Sheet| Data & Statistics| DHDSP| CDC. 2017. http://www.cdc .gov/dhdsp/data_statistics/fact_sheets/fs_atrial_fibrillation.htm. Accessed March 25, 2018.

32. Miyazaki S, Shah A, Scherr D, Haïssaguerre M. Atrial fibrillation: pathophysiology and current therapy. Ann Med. 2011;43(6):425–436. doi:10.3109/07853890.2011.554426. 33. Rosenthal L. Atrial Fibrillation. 2017. http://emedicine.medscape. com/article/151066-overview#a3. Accessed March 25, 2018. 34. Aryana A, Singh S, Kowalski M, et al. Acute and long-term outcomes of catheter ablation of atrial fibrillation using the second-generation cryoballoon versus open-irrigated radiofrequency: a multicenter experience. J Cardiovasc Electrophysiol. 2015;26(8):832–839. doi:10.1111/jce.12695. 35. Wasserlauf J, Pelchovitz D, Rhyner J, et al. Cryoballoon versus radiofrequency catheter ablation for paroxysmal atrial fibrillation. Pacing Clin Electrophysiol. 2015;38(4):483–489. doi:10.1111 /pace.12582. 36. Rosenthal L. Atrial Flutter: Practice Essentials, Background, Pathophysiology. 2017. http://emedicine.medscape.com/article/151210 -overview. Accessed March 25, 2018. 37. Olshansky B. Atrioventricular Nodal Reentry Tachycardia: Background, Etiology, Epidemiology. 2017. http://emedicine.medscape. com/article/160215-overview#a6. Accessed March 24, 2018. 38. Barold S, Ilercil A, Leonelli F, Herweg B. First-degree atrioventricular block. Clinical manifestations, indications for pacing, pacemaker management & consequences during cardiac resynchronization. J Interv Card Electrophysiol. 2006;2(17):139–152. 39. Cheng S. Long-term outcomes in individuals with prolonged PR interval or first-degree atrioventricular block. JAMA. 2009;301(24):2571. doi:10.1001/jama.2009.888. 40. Sovari A. Second-Degree Atrioventricular Block: Practice Essentials, Background, Pathophysiology. 2017. http://emedicine.medscape .com/article/161919-overview#a5. Accessed March 24, 2018. 41. Budzikowski A. Third-Degree Atrioventricular Block: Background, Pathophysiology, Etiology. 2015. http://emedicine.medscape.com /article/162007-overview. Accessed March 24, 2018. 42. Tracy C, Epstein A, Darbar D, et al. 2012 ACCF/AHA/HRS Focused Update of the 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Heart Rhythm. 2012;9(10):1737–1753. doi:10.1016/j.hrthm.2012.08.021. 43. Heart Block—Who Is at Risk for Heart Block? | National Heart, Lung, and Blood Institute (NHLBI). 2018. https://www.nhlbi.nih .gov/node/4310. Accessed March 24, 2018. 44. Mayo Clinic Staff. Tachycardia. 2018. https://www.mayoclinic.org /diseases-conditions/tachycardia/symptoms-causes/syc-20355127. Accessed March 24, 2018.

CHAPTER

15 © TairA/Shutterstock

Heart Failure

“A rude unhinging of the machinery of life.” —Thomas Edison, The Gross Clinic, 1875

OUTLINE Heart Failure Definition and Diagnosis Etiology Epidemiology of HF Pathophysiology of HF Clinical Manifestations Diagnostic Testing Treatment and Management Risk Factors Complications Prognosis The Cardiomyopathies Dilated Cardiomyopathy Hypertrophic Cardiomyopathy Restrictive Cardiomyopathy Summary of the Cardiomyopathies Valvular Heart Diseases Aortic Insufficiency (Aortic Regurgitation) Aortic Stenosis Mitral Regurgitation (Insufficiency) Mitral Stenosis Pulmonic Regurgitation Pulmonary Stenosis Tricuspid Regurgitation Tricuspid Stenosis Congenital Heart Disease Ventricular Septal Defects Atrial Septal Defect Pericardial Diseases Pericarditis Pericardial Effusion Cardiac Tamponade Left Ventricular Hypertrophy

OBJECTIVES 1. 2. 3. 4. 5. 6. 7. 8.

State the working definition of heart failure (HF). Outline the incidence, prevalence, and risk factors for HF. Discuss the etiologies of HF. Compare and contrast left-side and right-side HF. Define and discuss secondary problems associate with HF. Predict the clinical manifestations of a patient with HF. Explain diagnostic testing used to identify HF. Summarize the recommended management strategies for patients with HF. 9. Identify common complications associated with HF. 10. Discuss the prognosis of the different types of HF.

KEY TERMS Acute pericarditis Afterload AHA/ACC classification system Alcohol septal ablation (ASA) Alcoholic dilated cardiomyopathy (ACM) Aortic insufficiency (AI) Aortic stenosis (AS) Atrial septal defects (ASD) Cardiac tamponade Concentric hypertrophy Constrictive pericarditis Contractility Dilated cardiomyopathy (DCM) Eccentric hypertrophy Heart failure (HF)

Holosystolic murmur Hypertrophic cardiomyopathy Hypertrophic obstructive cardiomyopathy (HOCM) Idiopathic dilated cardiomyopathy (IDCM) Ischemic dilated cardiomyopathy (ICM) Ischemic heart disease Kussmaul sign Left heart failure Left-sided heart failure Left ventricular ejection fraction (LVEF) Left ventricular hypertrophy (LVH) Left ventricular outflow tract (LVOT)

391

392

CHAPTER 15  Heart Failure Mitral regurgitation (insufficiency) (MR) Mitral stenosis (MS) Nonrestrictive VSDs New York Heart Association (NYHA) functional classification Ostium primum defect

Ostium secundum defect Pericardial effusion Pericarditis Preload Pulmonary stenosis (PS) Pulmonic regurgitation (insufficiency) (PI)

Renin-angiotensinaldosterone system (RAAS) Restrictive cardiomyopathy (RCM) Restrictive VSDs Right heart failure Septal myomectomy

Sinus venosus defect Subacute pericarditis Tricuspid regurgitation (TR) Tricuspid stenosis (TS) Ventricular septal defect (VSD)

Case Study A 45-year-old-male office worker presents to the emergency department complaining of shortness of breath. Physical examination reveals the patient is slightly short of breath. The patient’s vital signs are blood pressure (BP) 110/65, respirations 23 breaths/minute, heart rate 106 beats/minute, temperature 98.4°F. The patient’s height is 73 inches, weight 295 pounds, and body mass index 39. Auscultation reveals S3 heart murmurs, fine crackles over the posterior lung bases, and no carotid bruit. The electrocardiogram (ECG) shows a left bundle branch block (LBBB) and left atrial enlargement (LAE; Figure 15-1).

The patient’s history reveals that he is a nonsmoker, does not use illicit drugs, but has been drinking about a 12 pack of beer a day for the last 8–10 years. The patient admitted to no exercise with a favorite pass time of television sports. His shortness of breath began a few months ago. At that time, he noticed that walking around at work caused him shortness of breath. Also, he noticed a bit of weight gain. His shoes became tight, and he had to sleep with three pillows to avoid shortness of breath (three-pillow orthopnea).

I

aVR

V1

V4

II

aVL

V2

V5

III

aVF

V3

V6

II

FIGURE 15-1  An ECG showing LAE and LBBB.

Heart Failure Heart failure (HF) is present when a weakened heart

muscle is unable to pump enough oxygenated blood to meet the metabolic demands of the body. As a result, the body does not receive a sufficient amount of oxygenated blood.1 HF is a clinical syndrome rather than a specific disease entity. HF can affect either the left or the right ventricle (RV) or both. Left ventricular (LV)

f­ ailure, or left HF, is the most common type of HF. The most common cause of right-side HF is left-side HF.2 According to statistics from 2007 to 2010, approximately 5.1 million people in the United States have HF. In 2009, 1 in 9 deaths was from HF. HF costs $32 billion a year in the United States.3 Numerous conditions or disease processes can cause HF.4 These cardiac diseases may include cardiomyopathy, valvular heart disease, congenital malformations, ischemic heart disease,

Heart Failure myocardial infarction (MI), and hypertension.5 This chapter reviews HF in general, and cardiomyopathy, valvular heart disease, congenital heart disease, pericardial disease, and hypertension as causes of HF. Chapter 16 addresses ischemic heart disease and MI.

KNOWLEDGE CHECK QUESTIONS 1. True or False: Hypertension does not lead to HF. 2. True or False: HF may be isolated to one side of the heart.

Definition and Diagnosis HF is a syndrome characterized by an inability of the heart to pump enough blood to meet the metabolic needs of the body.1 Figure 15-2 shows that the heart has four chambers: two atria and two ventricles. The LV pumps blood into the peripheral circulatory system, and the RV pumps blood into the pulmonary system. Veins bring blood back to the heart and arteries take blood away from the heart. This is a closed system, meaning the blood circulates inside this closed system repeatedly, picking up oxygen in the lungs and bringing it to the organs and peripheral tissues. HF results from the heart’s inability to fill with blood (diastolic dysfunction) or the inability of the heart to pump blood to the body (systolic dysfunction). This problem can affect the left side of the heart (left heart failure), the right side of the heart (right heart failure), or both sides of the heart.1 Figure 15-3 breaks down the heart into a series of interconnected pumps and tubing. This figure shows the four chambers of the heart in sequence. The two smaller

pumps represent the atria, and the larger pumps represent the ventricles. The ventricles differ in size and in the pressure they can generate to pump the blood forward. HF is a progressive disorder that results from a weakened heart muscle. This weakening is a consequence of an underlying cardiac issue.6 Identification of the underlying cardiac problem and its cause is crucial for proper treatment. Causes of these cardiac problems involve circulation, the pulmonary and neuroendocrine systems, and other organs.6 HF can occur acutely, as with endocarditis or MI. HF can also be a result of insults the heart has received over the course of an individual’s life.6 The main terminology used to ­identify left HF relies on the measurement of left ventricular ejection fraction (LVEF). The ejection fraction (EF) is the percentage of blood pumped out with each LV contraction. It is equal to the volume in the LV at the end of diastole minus the volume in the LV at the end of systole divided by the volume in the LV at the end of diastole. The EF categorizes two types of HF. One type has a reduced EF, HF-REF. The second type has preserved EF (PEF), which is more difficult to diagnose than HF-REF.6 Table 15-1 describes the conditions needed to diagnose HF-REF and HF-PEF. The diagnostic tests to identify HF include chest x-ray (CXR), blood work, heart catheterization, echocardiogram, electrocardiogram (ECG), treadmill exercise stress test, and a tracer study. Two methods are used to classify HF. The term HF describes the symptomatic syndrome, graded according to the New York Heart Association (NYHA) functional classification. The AHA/ACC classification system utilizes the progressiveness of HF and its risk factors. The AHA/ACCF scale allows an individual to move in both directions as their symptoms improve.7 Both classification methods appear side by side for comparison in Box 15-1.

Aorta Pulmonary artery Right atrium

Left atrium

Vena cava system

Right ventricle

Peripheral circulation FIGURE 15-2  The heart as a pump.

Pulmonary veins

Left ventricle

Pulmonary circulation

393

CHAPTER 15  Heart Failure Right ventricle

Pulmonary circulation

Left atrium

Left ventricle

Right atrium LA RA

RV LV

Peripheral circulation

One-way valves FIGURE 15-3  Simplified pump function of the normal heart. LA, left atrium; RA, right atrium. (Blue represents deoxygenated blood; red

represents oxygenated blood.)

TABLE 15-1 Diagnostic Criteria for Heart Failure Type of HF

CRITERIA

394

HFrEF

HFmrEF

1

Symptoms ± Signsa

Symptoms ± Signsa

Symptoms ± Signsa

2

LVEF 35 pg/ml and/or NT-proBNP > 125 pg/mL.

Developed with the special contribution of the Heart Failure Association (HFA) of the ESC, Eur Heart J. 2016:37(27): 2129–2200. doi:10.1093/eurheartj/ehw128

BOX 15-1 Comparison of HF Classifications7 American Heart Association/American College of Cardiology (AHA/ACC) Stage A—High risk for HF but without structural heart disease or symptoms of HF Stage B—Structural heart disease but without symptoms or signs of HF Stage C—Structural heart disease with prior or current symptoms of HF Stage D—Refractory HF requiring special interventions

NYHA Functional Class System Class I—No limitations of physical activity Class II—Slight limitations of physical activity and comfortable at rest Class III—Marked limitations of physical activity and comfortable at rest Class IIIa—No dyspnea at rest Class IIIb—Recent dyspnea at rest Class IV—Inability to carry on any physical activity without discomfort and symptoms present even at rest

Heart Failure

KNOWLEDGE CHECK QUESTIONS 1. True or False: HF occurs only when the EF is reduced. 2. True or False: The AHA/ACC use risk factors to classify HF.

Etiology In HF, the myocardium weakens and the muscle is no longer capable of pumping blood out to the body and the lungs. This diminished capacity of the heart to eject blood causes a backup of blood. Left HF causes a backup of blood in the lungs, leading to pulmonary edema. Right HF causes a backup of blood in the periphery or venous system, leading to edema in the extremities. In some cases, the blood can back up into both the lungs and the periphery.5 The weakening of the heart muscle is a consequence of other diseases or conditions.1 HF is the most severe consequence of all cardiac diseases. The causes of HF are reviewed in Box 15-2.

KNOWLEDGE CHECK QUESTIONS 1. True or False: Left HF causes pulmonary edema. 2. True or False: Right HF causes peripheral edema.

Epidemiology of HF HF has become a major public health problem in the United States and worldwide. In 1997, HF was an emerging epidemic.8 Currently, more than 5.8 million people in America and more than 23 million worldwide are diagnosed with HF. There are more than 550,000 new cases each year.8 In 2009, 1 in 9 deaths included HF as a contributing cause. Within 5 years of diagnosis with HF, approximately 50% die.9 The AHA projected that by the year 2030, the prevalence of HF is expected to increase 25% from the 2013 estimates.9 The total direct medical cost for HF in 2012 was $20.9 billion. This is expected to increase to $53.1 billion by 2030.9 The total indirect cost in 2012 was $9.8 billion and is expected to be $16.6 billion by 2030.10 HF among the different racial and ethnic groups is expected to increase substantially by 2030. The largest increase is projected to be in the black population (29%) followed by the white nonHispanic population. The lowest increases are expected in the white Hispanic population. The rate of HF among men and women is expected to grow similarly; however, men have a higher prevalence than women.10

KNOWLEDGE CHECK QUESTIONS 1. True or False: By the year 2030, the total direct medical cost for HF is expected to be less than $10 billion. 2. True or False: Men have a higher prevalence for HF than women.

BOX 15-2 Causes of HF Cardiomyopathy ƒƒ Dilated cardiomyopathy (DCM) yy Hypertrophic cardiomyopathy (HCM) yy Restrictive cardiomyopathy (RCM) yy Valvular heart disease ƒƒ Aortic valve regurgitation and stenosis yy Mitral valve regurgitation and stenosis yy Pulmonic valve regurgitation and stenosis yy Tricuspid valve regurgitation and stenosis yy Congenital heart disease ƒƒ Ventricular septal defects (VSDs) yy ASDs yy Pericardial disease ƒƒ Constrictive pericarditis yy Cardiac tamponade yy Hypertension ƒƒ Left ventricular hypertrophy (LVH) ƒƒ Ischemia ƒƒ

Pathophysiology of HF Numerous diseases/conditions can cause HF. The pathophysiology, clinical manifestations, diagnostic testing, complications, risk factors, and prognosis for each cause of HF are unique. Whatever the etiology, the consequence is either left-sided HF, or right-sided HF, or both. The three determinants of ventricular function include preload, afterload, and contractility (Box 15-3). Preload is the amount of ventricular stretch at the end of diastole, just before the initiation of contraction. The measurement of preload is left ventricular end-diastolic pressure (LVEDP). Afterload is the amount of resistance

BOX 15-3 Determinants of Ventricular Function or Stroke Volume Preload ƒƒ Afterload ƒƒ Contractility ƒƒ

395

396

CHAPTER 15  Heart Failure

FIGURE 15-4  Normal diastole and systole. © udaix/Shutterstock.

the heart needs to overcome to open the aortic valve and pump out blood volume into the systemic circulation. It is the forces that oppose ejection of blood out of the ventricle and is the systemic vascular resistance (SVR). Contractility refers to the internal strength of the ventricle to squeeze the blood out of its chamber. Left-sided heart failure is a result of impaired LV function. Figure 15-4 shows normal diastole and systole. Impaired cardiac muscle contractility will cause systolic dysfunction and impaired diastolic filling results in diastolic dysfunction.10 In either case, the blood volume that remains in the LV after contraction ends increases, resulting in an increase in the LVEDP or preload. However, in hypertrophic obstructive cardiomyopathy, RCM, or mitral stenosis (MS), the LV pressure decreases, reducing preload.11 A systolic problem results from LV myocardium weakness or overstretch. This causes a contractile impairment. In either case, the blood volume in the LV increases, ultimately causing the LV to dilate. The blood backs up into the LA, pulmonary veins, and lungs, eventually causing pulmonary edema. Figure 15-5 shows pulmonary edema caused by left-sided HF. Typically, this occurs in males between 50 and 70 years who have had a MI.12 A diastolic problem results from the muscle of the LV becoming stiff and noncompliant, restricting ventricular filling. In restricted ventricular filling, the

myocardium cannot relax to accept the optimal amount of blood. The results lead to a backup of blood in the lungs and pulmonary edema. Women, overweight individuals, and elderly, with high BP and diabetes, most often have diastolic HF. MS is another cause of restricted filling and diastolic HF.12 Right-sided HF in most cases results from left-sided HF. When the right side fails, blood backs up into the systemic venous system, causing venous congestion.12 Consequently, the patient has swollen legs, liver enlargement, and jugular vein distention (JVD).12 Pulmonary hypertension (PH) and chronic obstructive pulmonary disease (COPD) are other common causes of right-sided HF.12 Figure 15-6 shows systemic edema caused by right HF. Table 15-2 demonstrates the pathophysiology of HF with clinical examples. Although pump failure is a key component of HF, the progression of the disease and ­exacerbations of acute HF are manifestations of maladaptive neurohormonal responses that occur during HF. These neurohormonal responses include activation of the sympathetic nervous system, the renin–angiotensin–aldosterone system (RAAS), and antidiuretic hormone. One of the first responses to decreasing cardiac output is the activation of the sympathetic nervous system to release norepinephrine, in an attempt to improve cardiac output. Norepinephrine is also a potent vasoconstrictor that keeps

Heart Failure

Right ventricle

Pulmonary artery

Increased hydrostatic pressure

Pulmonary Left vein “backed atrium up”

Left ventricle

Right atrium LA RV

RA

Transudation of fluid into the alveolar space

LV Increased preload

Left ventricle failure

Left Heart Failure Peripheral circulation

Increased systemic vascular resistance (increased afterload)

One-way valves FIGURE 15-5  Pulmonary edema caused by left-sided HF, resulting in fluid buildup in the alveolar spaces. Right ventricle

Left atrium

Left ventricle

Right atrium LA RV

RA

Increased pulmonary vascular resistance

Venous congestion Jugular vein distention

LV

Right Heart Failure

Swollen legs Liver enlargement

One-way valves FIGURE 15-6  Systemic edema due to right HF.

organ perfusion stable. Activation of the RAAS also promotes vasoconstriction, and increasing levels of antidiuretic hormone promote water reabsorption. Also, the atrial natriuretic peptide (NP) is increased.

These neurohormonal responses are beneficial in the short term but are deleterious in the long term. These effects can aggravate HF by increasing ventricular afterload, which depresses stroke volume and increases

397

398

CHAPTER 15  Heart Failure

TABLE 15-2 Pathophysiology of HF with Clinical Examples

TABLE 15-3 Signs and Symptoms Typical of Heart Failure

Pathophysiology

Explanation

Clinical Examples

Symptoms

Signs

Contractility impairment

The myocardium is unable to increase the strength of contraction independent of the preload and afterload.

• DCM • Ischemia • Myocarditis

Typical

More Specific

Breathlessness Orthopnoea Paroxysmal nocturnal dyspnea Reduced exercise tolerance Fatigue, tiredness, increased time to recover after exercise Ankle swelling

Elevated jugular venous pressure Hepatojugular reflux Third heart sound (gallop rhythm) Laterally displaced apical impulse

Restricted filling

There is decrease in the compliance of the ventricle, causing an inability to fill.

• • • •

Less Typical

Less Specific

Pressure overload

A sustained increase in afterload ≥160 mm Hg causes a decrease in cardiac output.

• Aortic stenosis (AS) • Pulmonary stenosis (PS) • Systemic hypertension • Pulmonary embolism • PH

Nocturnal cough Wheezing Bloated feeling Loss of appetite Confusion (especially in the elderly) Depression Palpitations Dizziness Syncope Bendopnea

Volume overload

Progressive regurgitation of blood back into the atria or ventricle (or between atria or ventricles) causes decreased cardiac output.

• Mitral regurgitation (MR) • Aortic regurgitation • Pulmonary regurgitation • Tricuspid regurgitation (TR) • Septal defects

Weight gain (>2 kg/week) Weight loss (in advanced HF) Tissue wasting (cachexia) Cardiac murmur Peripheral oedema (ankle, sacral, scrotal) Pulmonary crepitations Reduced air entry and dullness to percussion at lung bases (pleural effusion) Tachycardia Irregular pulse Tachypnoea Cheyne Stokes respiration Hepatomegaly Ascites Cold extremities Oliguria Narrow pulse pressure

Rates too fast or too slow decrease cardiac output.

• Tachycardia • Bradycardia

Arrhythmia

RCM HCM MS Tricuspid stenosis (TS) • Constrictive pericarditis • Cardiac tamponade

preload to the point of pulmonary and/or systemic congestion and edema.13 HF is typically a chronic disease with several natural compensatory mechanisms. Acute HF is life threatening. It may develop in a previously asymptomatic patient with acute coronary syndrome or acute valvular regurgitation. Additionally, it can complicate chronic HF. In either case, it requires hospitalization and prompt interventions.

KNOWLEDGE CHECK QUESTIONS 1. True or False: Afterload is the amount of ventricular stretch at the end of diastole. 2. True or False: Preload is measured using LVEDP. 3. True or False: A sustained increase in afterload of more than 160 mm Hg causes a decrease in cardiac output.

HF = heart failure. Developed with the special contribution of the Heart Failure Association (HFA) of the ESC. Eur Heart J. 2016:37(27): 2129–2200. doi:10.1093/eurheartj /ehw128

Clinical Manifestations Regardless of the cause of HF, some of the clinical manifestations are the same. See Table 15-3. Each disease/ conditions that can cause HF have additional manifestations that are unique. The heart’s ability to compensate for changing conditions hides clinical symptoms at first. When they do occur, the majority of the signs and symptoms of HF are secondary compensatory mechanisms responding to a fall in cardiac output. The progression of HF causes fluid buildup in the pulmonary and systemic venous system. The dominant symptoms in HF are shortness of breath (dyspnea) and fatigue. Other complaints may include swelling of the extremities, weight gain, frequent urination, and a paroxysmal nocturnal cough.1 The physical findings of HF depend on the severity and chronicity of the condition. The lack of appetite and the increased metabolic demands of breathing can lead to the patient appearing frail or cachectic. Fluid retention leading to peripheral edema may be present in the legs or back and is most often due to right HF. Elevated filling pressures and TR may cause an enlarged liver. Right HF causes JVD via the hepatojugular reflux.

Heart Failure

Right heart failure

Left heart failure

Venous congestion

Peripheral edema Ascites

Pulmonary congestion

GI congestion

Liver congestion

Impaired gas exchange

Pulmonary congestion Pulmonary edema

Weight loss Anorexia GI distress

Liver impairment

Hypoxia Cyanosis

Cough with frothy sputum Orthopnea Paroxysmal nocturnal dyspnea

Decreased cardiac output

Decreased tissue perfusion Fatigue

FIGURE 15-7  Clinical manifestations of both right and left HF. GI, gastrointestinal.

Auscultation of the lungs can reveal crackles heard over the bases or dependent regions of the lungs. This is indicative of pulmonary edema. The presence of pulmonary edema is a sign of acute left HF caused by elevated capillary hydrostatic pressure pushing fluid into the interstitial spaces and alveoli. Compression of the conducting airways by pulmonary congestion may produce coarse rhonchi and wheezing. Cardiac auscultation can reveal an early diastolic sound (S3) indicative of systolic HF. A late diastolic sound (S4) results from a diastolic dysfunction. A thorough history and physical examination assist in the identification of HF, but most of the symptoms are nonspecific and frequently present in a host of other conditions. The most notable of those is COPD, which is a frequent confounder in the diagnosis of HF.13 Figure 15-7 shows the manifestations of left and right HF.

KNOWLEDGE CHECK QUESTIONS 1. True or False: The presence of the third heart sound (S3) is normal.

2. True or False: A diastolic dysfunction causes the fourth heart sound (S4). 3. True or False: Left HF causes liver congestion.

Diagnostic Testing Diagnostic testing for HF includes the measurement and monitoring of cardiac function. These tests include CXR, electrocardiography, routine laboratory evaluation, and NP assays.

FIGURE 15-8  Anteroposterior CXR of a patient with HF.

Chest Radiography A CXR is routine in the evaluation of the patient with shortness of breath. The CXR is useful in the identification of pulmonary venous congestion, interstitial edema, alveolar edema (pulmonary edema), cardiomegaly, and pleural effusions. The presence of these increases the likelihood of HF, but it does not rule out other possibilities. Kerley B lines on a CXR indicate pulmonary venous congestion or interstitial edema due to interlobular edema. Pulmonary edema shows up as opacification of the air spaces. See Figure 15-8.

399

400

CHAPTER 15  Heart Failure

Electrocardiography All suspected HF patients have an ECG done. Although the ECG is not a good predictor of HF, it is useful in determining the etiology of the HF together with other diagnostic tests. See Table 15-4 for the common abnormalities found on the ECG with HF.13

Echocardiography The echocardiogram provides immediate information on chamber volumes, ventricular systolic and diastolic function, ventricular wall thickness, and valve function.5 Together with the ECG, it is the most useful test for patients with suspected HF. The echocardiogram is critical to the determination of appropriate therapy.

Laboratory Tests Patients suspected of HF have blood tests that include serum electrolytes, renal function, complete blood count, and cardiac markers. Table 15-5 summarizes the

common lab tests and causes of abnormalities and their clinical implications. Many times the signs and symptoms of patients with suspected HF are nonspecific, and the echocardiogram shows no important cardiac abnormalities. In this case, cardiac markers are vital to the diagnosis. There is a family of hormones secreted in increased amounts when the heart is diseased or the load on any chamber in increased. The NPs increase in response to LV stretch due to high filling pressures.13 The two markers are B-type natriuretic peptide and N-terminal proB-type NP (NT-BNP). See Figure 15-9. The use of NP tests in conjunction with a standard clinical evaluation can help to identify a majority of patients with HF. BNP is most useful in distinguishing acute HF from other causes of dyspnea.13 When HF is suspected, NP tests, or echocardiogram, or both are necessary depending on test results. Figure 15-10 is an example of an algorithm for the diagnosis of HF using both echocardiogram and NP tests.

TABLE 15-4 Most Common Abnormalities on the ECG in HF Abnormality

Causes

Clinical Implications

Sinus tachycardia

Decompensated HF, anemia, hyperthyroidism

Clinical assessment Laboratory investigation

Sinus bradycardia

Beta-blockade, digoxin, ivabradine, verapamil, diltiazem Antiarrhythmics Sick sinus syndrome

Review drug therapy Laboratory investigation

Atrial tachycardia/ flutter/fibrillation

Hyperthyroidism, infection, mitral valve disease Decompensated HF, infarction

Slow AV conduction, anticoagulation, pharmacologic cardioversion, electrical cardioversion, catheter ablation

Ventricular arrhythmias

Ischemia, infarction, cardiomyopathy, myocarditis, hypokalemia, hypomagnesemia Digitalis overdose

Laboratory investigation Exercise test, perfusion studies, coronary angiography, electrophysiology testing, internal cardiac defibrillator

Myocardial ischemia/ infarction

Coronary artery disease (CAD)

Echocardiogram, troponins, perfusion study, coronary angiography, revascularization

Q waves

Infarction, HCM, LBBB, pre-excitation

Echocardiogram, perfusion studies, coronary angiography

LVH

Hypertension, aortic valve disease, HCM

Echocardiogram, cardiac magnetic resonance (CMR)

AV block

Infarction, drug toxicity, myocarditis, sarcoidosis, genetic cardiomyopathy, Lyme disease

Review drug therapy, evaluate for systemic disease, family history/genetic testing indicated, pacemaker or Implantable cardioverter defibrillator (ICD) indicated

Low QRS voltage

Obesity, emphysema, pericardial effusion, amyloidosis

Echocardiogram/CMR, CXR; for amyloidosis, consider further imaging and endomyocardial biopsy

QRS duration ≥ 120 ms and LBBB morphology

Electrical and mechanical dyssynchrony

Echocardiogram Pacemaker Pacemaker/defibrillator

Reproduced from ESC guidelines for the diagnosis and treatment of acute and chronic heart failure 2012. Eur Heart J. 2012;33:1787–1847. doi:10.1093 /eurheart/ehs104.

Heart Failure

TABLE 15-5 Common Laboratory Test Abnormalities in HF Abnormality

Causes

Clinical Implications

Renal impairment (creatinine > 150 µmol/L 1.7 mg/dL, eGFR < 60 mL/ min/1.73 m2)

Renal disease Renal congestion Angiotensin-converting enzyme (ACE) inhibitor/angiotensin-receptor blocker (ARB), Mineralocorticoid receptor antagonist (MRA) Dehydration NSAIDs and other nephrotoxic drugs

Calculate eGRF Consider reducing ACE inhibitor/ARB or MRA dosage (or postpone dose up-titration) Check potassium and BUN Consider reducing diuretic dose if dehydrated, but if there is renal congestion, more diuresis may help Review drug therapy

Anemia (8.4 mg/dL)

Diuretic treatment, gout, malignancy

Allopurinol Reduce diuretic dose

Albumin high (>45 g/L)

Dehydration

Rehydrate

Albumin low ( 3.5

Anticoagulant overdose Liver congestion/disease Drug interactions

Review anticoagulant dose Assess liver function Review drug therapy

CRP > 10 mg/L, neutrophilic leukocytosis

Infection, inflammation

Diagnostic workup

Reproduced from ESC guidelines for the diagnosis and treatment of acute and chronic heart failure 2012. Eur Heart J. 2012;33:1787–1847. doi:10.1093 /eurheart/ehs104.

401

402

CHAPTER 15  Heart Failure

Clinical examination, ECG, CXR

Natriuretic peptides

BNP 2000 pg/mL

Acute HF unlikely

Uncertain diagnosis

Acute HF likely

FIGURE 15-9  Flowchart for the diagnosis of acute HF with NP in patients with suggestive symptoms. Kirk J, Diercks D, Dhingr K. Acute heart failure. In: Aghababian R, ed. Essentials of Emergency Medicine. 2nd ed. Sudbury, CA: Jones & Bartlett Learning; 2011:122–129.

PATIENT WITH SUSPECTED HFa (non-acute onset)

ASSESSMENT OF HF PROBABILITY 1. Clinical history: History of CAD (MI, revascularization) History of arterial hypertension Exposition to cardiotoxic drug/radiation Use of diuretics Orthopnoea/paroxysmal nocturnal dyspnoea 2. Physical examination: Rales Bilateral ankle oedema Heart murmur Jugular venous dilatation Laterally displaced/broadened apical beat 3. ECG: Any abnormality

All absent

≥I present Assessment of natriuretic peptides not routinely done in clinical practice

NATRIURETIC PEPTIDES

No

• NT-proBNP ≥125 pg/mL • BNP ≥35 pg/mL

HF unlikely: consider other diagnosis

Yes Echocardiography

Normalb,c

If HF confirmed (based on all available data): determine aetiology and start appropriate treatment FIGURE 15-10  An example of a diagnostic flowchart for patients with suspected non-acute heart failure. Developed with the special contribution of the Heart Failure Association (HFA) of the ESC, Eur Heart J. 2016;37(27):2129–2200. doi:10.1093/eurheartj/ehw128.

Heart Failure

KNOWLEDGE CHECK QUESTIONS

TABLE 15-6 Medications Used for HF

1. True or False: HF can cause a pleural effusion that is seen on CXR.

Medication

Reason

ACE inhibitors

To reduce the risk of HF hospitalization and the risk of premature death. Use with betablocker for all patients with an EF ≤ 40%.

Beta-blockers

Use with ACE inhibitor Use with ARB if ACE inhibitor is not tolerated, for all patients with EF ≤ 40%, to reduce the risk of HF hospitalization and the risk of premature death.

MRA

Use for patients with persisting symptoms and an EF ≤ 35%, despite treatment with an ACE inhibitor (or an ARB) and a beta-blocker, to reduce the risk of HF hospitalization and the risk of premature death.

Diuretics

Use as first-line, short-term therapy in the emergency management of patients with acute HF to remove excess fluid in patients with signs of congestion from volume overload.

Supplemental oxygen

Use for a patient with documented or suspected hypoxemia.

2. True or False: Ventricular function, ventricular wall thickness, and valve function can be determined using echocardiography. 3. True or False: Echocardiography is most useful in distinguishing acute HF from other causes of dyspnea.

Treatment and Management The overall goals of treatment in patients with HF are to relieve the signs and symptoms, prevent hospital admission, and improve survival.5 Box 15-4 shows the goals for treatment in acute HF. Regardless of the cause of HF, some of the treatments are similar. Other treatment strategies for HF are unique to the specific etiology. The treatment of all forms of HF requires lifestyle changes. The general pharmacologic treatments indicated for HF appear in Table 15-6.

BOX 15-4 Goals of Treatment in Acute HF Immediate (ED/ICU/CCU) Improve haemodynamics and organ perfusion. Restore oxygenation. Alleviate symptoms. Limit cardiac and renal damage. Prevent thrombo-embolism. Minimize ICU length of stay. Intermediate (in hospital) Identify aetiology and relevant co-morbidities. Titrate therapy to control symptoms and congestion and optimize blood pressure. Initiate and up-titrate disease-modifying pharmacological therapy. Consider device therapy in appropriate patients. Pre-discharge and long-term management Develop a careplan that provides: A schedule for up-titration and monitoring ƒƒ of pharmacological therapy. Need and timing for review for device therapy. ƒƒ Who will see the patient for follow-up and when. ƒƒ Enrol in disease management programme, educate, and initiate appropriate lifestyle adjustments. Prevent early readmission. Improve symptoms, quality of life, and survival. CCU, coronary care unit; ED, emergency department; ICU, intensive care unit. Developed with the special contribution of the Heart Failure Association (HFA) of the ESC, European Heart Journal 2016; 37 (27): 2129–2200, doi:10.1093/eurheartj/ehw128

Other pharmacologic agents or surgical intervention may be appropriate depending on the etiology of the HF.

KNOWLEDGE CHECK QUESTIONS 1. True or False: All HF patients with EFs less than 40% should initially be treated with an ACE inhibitor and a beta-blocker. 2. True or False: HF patients with pulmonary edema are treated with diuretics.

Risk Factors Early identification of risk factors for the development of HF is important for preventive interventions. Preventive measures need to be in place before the appearance of ventricular dysfunction to reduce the risk of HF. The AHA/ACC system uses risk factors to classify HF, shown in Figure 15-11. The important risk factors for the development of HF include hypertension, atherosclerotic disease, diabetes mellitus, obesity, metabolic syndrome, patients who use cardiotoxic drugs, and those with a family history of cardiomyopathy. Metabolic syndrome is the name for a group of risk factors that include obesity, high triglyceride level, low high-density lipid level, hypertension, and high fasting blood sugar level. Cardiotoxic drugs are substances that may trigger the development of cardiac injury even when properly used. These drugs include amphetamine, anabolicandrogenic steroids, catecholamines, cocaine, ephedrine, pentamidine, and tricyclic antidepressants.

403

404

CHAPTER 15  Heart Failure Stage A At high risk for HF but without structural heart disease or symptoms of HF Patients with: Hypertension Atherosclerotic disease Diabetes mellitus Obesity Metabolic syndrome Patients Using cardiotoxins With family history of cardiomyopathy Structural heart disease Stage B Structural heart disease but without symptoms or signs of HF Patients with: Previous myocardial infarction Left ventricular remodeling (left ventricular hypertrophy/low ejection fraction) Asymptomatic valvular disease Development of HF symptoms Stage C Structural heart disease with prior or current symptoms of HF Patients with: Known structural heart disease AND Dyspnea, fatigue, reduced exercise tolerance Refractory HF symptoms at rest Stage D Refractory HF requiring special interventions Patients with: Marked symptoms at rest despite maximal medical therapy

FIGURE 15-11  AHA and ACC HF classification. Reproduced with permission from Georgiopoulou V, Kalogeropoulow A, Butler J. Heart failure in hypertension: prevention and treatment. Drugs. 2012;72(10):1373–1398.

KNOWLEDGE CHECK QUESTIONS 1. True or False: Patients with diabetes mellitus have a high risk for the development of HF. 2. True or False: A patient with a known structural heart disease and symptoms is classified as Stage B according to the AHA/ACC.

Complications The complications from HF depend on the cause of the HF and its severity. Renal damage or failure can occur from kidney hypoperfusion during times of low cardiac output. Erythropoietin (which stimulates RBC production) secreted by the kidneys is reduced by kidney

damage, causing anemia. Right HF causes fluid buildup in the liver, causing cardiac cirrhosis or congestive hepatopathy. The heart valves can be affected by HF due to the increased cardiac workload. The most common valve problem caused by HF is MR. Arrhythmias, such as atrial fibrillation (AF) or ventricular fibrillation, can occur due to damage to the heart’s electrical system. Unintentional weight loss, cardiac cachexia, is yet another complication from HF.7

KNOWLEDGE CHECK QUESTIONS 1. True or False: Hyperperfusion of the kidneys occurs during HF and causes renal failure. 2. True or False: Congestive hepatopathy is caused by left HF.

Prognosis Numerous variables provide prognostic information about HF. The most common of these variables include age, etiology, NYHA classification, EF, and the presence of key comorbidities, such as diabetes, renal dysfunction, and anemia. These variables do change with time and require frequent assessment. This assessment is particularly important to the patient’s prognosis and the course of treatment, for example, the need for device implantation; surgery, including transplantation; and planning end-of-life care.

KNOWLEDGE CHECK QUESTIONS 1. True or False: The presence of comorbidities is a major factor in a patient’s prognosis for HF. 2. True or False: The prognosis for HF can change with treatment.

The Cardiomyopathies The cardiomyopathies are a group of heart disorders that cause changes in the structure and function of the myocardium that is either idiopathic in nature (primary) or caused by another disorder of the heart or other organs (secondary).14 The World Health Organization has identified three types of cardiomyopathies: dilate cardiomyopathy, HCM, and RCM. Anatomic appearance and abnormal physiology of the LV is the basis for this classification. These disorders often result in the symptoms of HF reviewed previously.

Dilated Cardiomyopathy Dilated cardiomyopathy (DCM), once known as conges-

tive cardiomyopathy, is the most common type of cardiomyopathy.15 Myocyte damage and cardiac enlargement

The Cardiomyopathies in DCM result from a wide spectrum of genetic, inflammatory, toxic, and metabolic causes.14 See Box 15-5. Although the etiology of each type is different, they cause the same structural abnormality. The hallmark of DCM is ventricular dilatation with decreased contractile function. This results in excessive blood accumulating in the affected ventricle, causing volume overload. At first, the extra blood increases the stretch of the myocardium, causing LVEF and cardiac output to increase as a compensatory mechanism. However, as the volume within the LV increases, its walls become stretched and thin (Figure 15-12). Ultimately both the EF

BOX 15-5 Examples of Dilated Cardiomyopathies Idiopathic ƒƒ Ischemic heart disease ƒƒ Genetic ƒƒ Inflammatory ƒƒ Infectious (especially viral) yy Noninfectious yy Connective tissue diseases Peripartum cardiomyopathy {{ Sarcoidosis Toxic ƒƒ Chronic alcohol ingestion yy Chemotherapeutic agents yy Metabolic ƒƒ Hypothyroidism yy Chronic hypocalcemia or hypophosphatemia yy Neuromuscular ƒƒ Muscular or myotonic dystrophy yy {{ {{

Reproduced from Lee C, Dec G, Lilly L. The Cardiomyopathies. In: Lilly L, ed. Pathophysiology of Heart Disease. 6th ed. Philadelphia: Lippincott Williams & Wilkins; 2015.

Weakened heart muscle Enlarged ventricle

FIGURE 15-12  Dilated cardiomyopathy.

and the cardiac output decrease. This can cause cardiogenic pulmonary edema. Without prompt treatment, congestive heart failure (CHF) and possible death occur.14,15 Acute viral myocarditis afflicts young, previously healthy people, with some of these individuals progressing to DCM. Alcoholic DCM develops in a small number of people who consume alcoholic beverages excessively and chronically. Postpartum DCM causes the presentation of HF symptoms between the last month of pregnancy and up to 6 months postpartum. Risk factors for postpartum DCM include being African American, older maternal age, and having multiple pregnancies. Genetic DCM is responsible for approximately 20–30% of idiopathic DCM (IDCM).14 In the early stages of DCM, the heart is usually able to compensate for the increased volume and the patient is asymptomatic. However, as heart function declines, signs and symptoms appear.15 The clinical manifestations of DCM are those of CHF. See Table 15-3. Common signs and symptoms include fatigue, shortness of breath on exertion, decreased tissue perfusion, and swelling of the lower extremities. Other signs and symptoms include weight gain, orthopnea, fainting, palpitations, dizziness or light headedness, chest pain or pressure, loss of appetite, decreased concentration, cough, paroxysmal nocturnal dyspnea, ascites, and arrhythmias (tachycardia, fibrillation).15,16 Another consequence of reduced cardiac output is blood pooling in both the ventricles and the atria, leading to clot formation. The presence of clots increases the risk of acute MI, leg ischemia, stroke, or pulmonary embolus.15 With a persistent reduction in cardiac output, the decline in renal blood flow prompts the kidneys to secrete increased amounts of renin. This activation of the RAAS increases peripheral vascular resistance and intravascular volume. These effects are also initially helpful in buffering the fall in cardiac output. However, the compensatory effects of the RAAS prove detrimental and contribute to pathologic myocardial remodeling and fibrosis.14 The diagnosis of DCM begins with the patient’s history and a physical examination. This helps to eliminate other causes of ventricular failure.17 If the diagnosis is inconclusive after the history and physical exam, the tests seen in Table 15-7 are used to make the diagnosis of DCM. When the medications described earlier in the HF section of this chapter are unable to control the patient’s symptoms, an implantable medical device may be necessary. All of these devices are designed to pace the heart but have additional functions as well.14 Table 15-8 shows common medical devices used to treat electrical conduction abnormalities associated with DCM and other forms of HF. See Figure 15-13. If medical and device therapy is insufficient to manage end-stage HF, heart transplantation may be indicated.14 The presence of AF, a previous thromboembolic event, or an intracardiac thrombus, is an indication for the use of anticoagulation therapy.

405

406

CHAPTER 15  Heart Failure

TABLE 15-7 Diagnostic Tests for DCM Diagnostic Test

Identifiers

Blood tests

• Elevated troponin • Elevated BNP

Cardiac magnetic resonance imaging (CMRI)

• Identifies myocardial structure and function • May show abnormal myocardial tissue texture or scarring

CXR

• Cardiomegaly • Pleural effusion from elevated pulmonary venous pressure (most common on the right side)

Coronary angiography

• Used if other diagnostic tests are inconclusive • For patients with high risk for CAD, chest pain, elderly, and those with several cardiovascular risk factors

ECG

• Reveals arrhythmias: nonspecific STsegment depression, inverted T waves, and LBBB • Reveals signs of previous MI: pathologic Q waves in precordial leads

Echocardiogram

• Reveals dilated and hypokinetic heart chambers • Rules out valvular disorders • Shows wall motion abnormalities • Shows stationary thrombus against chamber wall (mural thrombus)

Positron-emission tomography

• Diagnoses cardiac sarcoidosis • Diagnoses RCM

TABLE 15-8 Medical Devices for DCM and Their Function Device Name

Device Function

ICD

The ICD can sense life-threatening arrhythmias (V-fib or V-tach) and automatically deliver the appropriate electrical shock to correct them. ICD reduces arrhythmic deaths in patients with DCM.

Cardiac resynchronization therapy (CRT)

The CRT is a pacemaker that paces both the RV and the LV, and may also include an ICD.

Right ventricular assist device (RVAD)

The RVAD is a surgically implanted medical device that helps the RV pump blood to the lungs.

Left ventricular assist device (LVAD)

The LVAD is a surgically implanted medical device that helps the LV pump blood to the body.

Risk factors for DCM include family history of cardiomyopathy, HF, or sudden cardiac arrest (SCA), coronary heart disease (CHD), MI, viral infection, diabetes, severe obesity, RCM, long-term alcoholism, or longterm high BP.18

FIGURE 15-13  A cardiologist implants a heart defibrillator in a

patient. The ICD also includes a pacemaker. © Carolina K. Smith MD/Shutterstock.

Complications from all forms of DCM include HF, heart valve regurgitation, enlargement of the left or RV, pulmonary or systemic edema, cardiac arrhythmias, SCA, and system or pulmonary emboli.19 If left untreated, DCM leads to HF. Identification of the cause (viral, bacterial, CAD, ischemic, or alcohol) and its correction (antivirals, antibiotics, angioplasty, or abstinence from alcohol) may lead to some improvement. The etiology of the DCM is the number one factor in its prognosis. Other factors affecting the prognosis include increased age, male gender, and severe CHF. If CHF develops, approximately 50% of the patients die within 5 years. There is a 50% mortality rate each year after a diagnosis of severe HF. If the HF is mild and optimal medical therapy is given, the prognosis improves.20

Ischemic Dilated Cardiomyopathy The cause of ischemic dilated cardiomyopathy (ICM) is CAD. This is the only DCM that is caused by ischemia. All other types of DCM are considered non-ischemic. CAD is the narrowing of the lumen of the coronary arteries caused by plaque buildup. One of the consequences of CAD is a MI. This causes the myocardium to become weak and unable to pump efficiently. The inefficient pump leads to a decrease in the EF, causing volume overload. This results in DCM.14 The treatment for ICM is repair of the coronary artery by angioplasty and stenting. See Chapter 16.

Alcoholic Dilated Cardiomyopathy Alcoholic dilated cardiomyopathy (ACM) is caused by

dilation of the LV due to alcohol abuse.14 Although there is extensive research on ACM, the exact pathogenesis of ACM is not fully understood.21 In long-term alcohol consumption, there are changes at the cellular level, including intracellular organelle dysfunction, contractile proteins dysfunction, and calcium homeostasis.21 These changes cause myocyte dysfunction. The incidence of ACM is lower in women as compared to men, and occurs most often in alcoholics in their late 40s. It is not

The Cardiomyopathies clear how much alcohol consumption is necessary, but individuals who drink more than eight drinks per day for at least 5 years are at risk. The best treatment is to abstain from alcohol consumption.21

Case Study The case study patient has revealed the symptoms of HF: shortness of breath, orthopnea, and swollen lower extremities. He has fine crackles in the posterior lung bases consistent with pulmonary edema from left-sided HF and has peripheral edema consistent with right-sided HF. The S3 murmur is consistent with left-sided HF. His ECG shows a LBBB and LA enlargement. All findings point to HF, the etiology of which is not smoking. However, his excessive alcohol intake makes him a candidate for the diagnosis of alcoholic cardiomyopathy. Further tests are needed to make that diagnosis, including Doppler echocardiogram and blood tests.

Idiopathic Dilated Cardiomyopathy A diagnosis of idiopathic dilated cardiomyopathy (IDCM) occurs when the cause of cardiomyopathy is unknown. IDCM accounts for approximately 50% of all cases of cardiomyopathy.22 The possible triggers for IDCM appear in Table 15-9. When a virus causes IDCM, it can be from virus-positive or virus-negative infection. For a viruspositive infection, using high doses of intravenous TABLE 15-9 Possible Triggers of IDCM Classification of IDCM

Causative Agents/Factors

Toxic cardiomyopathy

Cocaine, lithium, cobalt, lead, arsenic, radiation, catecholamines, phenothiazines, and chemotherapy

Metabolic cardiomyopathy

Diabetes mellitus, hyperthyroidism, hypothyroidism, hyperparathyroidism, pheochromocytoma

Tachycardia-induced cardiomyopathy

Sustained rapid ventricular rates from supraventricular tachyarrhythmia, ventricular tachycardia, frequent premature ventricular complexes

Inherited

Autosomal dominant transmission of mutated genes encoding cytoskeletal and sarcomeric proteins

Virus infection

Adenovirus, enteroviruses, parvovirus B19 (B19V), human herpes virus-6

Other

Amyloidosis, Gaucher disease, Hurler disease, Hunter disease

immunoglobulin (2 g/kg) has demonstrated favorable effects on both cardiac function and virus elimination. This treatment has been shown to eliminate the B19V; this is a parvovirus and is the most frequently found virus in cardiac biopsies.22 Using an immunosuppressive therapy in a virus-negative infection has shown beneficial effects on myocardial function.22

Hypertrophic Cardiomyopathy Hypertrophic cardiomyopathy (HCM) is hypertrophy of

mainly the LV myocardium by more than 1.5 cm.23 See Figure 15-6. HCM is genetic. Its cause is the inheritance of mutated genes. The proteins encoded by the responsible genes are all part of the sarcomere complex and impair the contractile function of the ventricles. HCM is common with an incidence of about 1 in 500 people. It can occur at any age, and affects men more than women and African Americans more than Caucasians.23 This cardiomyopathy is the cause of sudden death in young athletes during vigorous physical exertion (Figure 15-14). In HCM, the cells of the heart muscle become enlarged, causing ventricular hypertrophy (ventricle wall thickening). The hypertrophy reduces the compliance and relaxation ability of the ventricles, impairing their ability to fill. This thickening can be either obstructive or nonobstructive. Nonobstructive HCM is less common than its obstructive counterpart. The nonobstructive type is due to symmetrical hypertrophy of the ventricular walls. This hypertrophy can also occur only in the apex or mid-region of the LV.

Hypertrophic Obstructive Cardiomyopathy If there is an asymmetric hypertrophy of the upper interventricular septum, a transient obstruction of the LV outflow tract (LVOT) may occur during systole. This is called hypertrophic obstructive cardiomyopathy (HOCM).24 With time, the LVH and small LV chamber size regress and lead to DCM, which can lead to left-sided HF.23

Thickened heart muscle

FIGURE 15-14  Hypertrophic cardiomyopathy.

407

408

CHAPTER 15  Heart Failure

Sigmoidal HCM 40–50%

Reverse curve HCM 30–40% Blood leaks back through the mitral valve = mitral regurgitation

Mitral valve presses against the septum causing an obstruction to blood flow FIGURE 15-15  Common septal morphologies in HOCM. Redrawn from Bos J, Towbin J, Ackerman M. Diagnostic, prognostic, and therapeutic implications of genetic testing for hypertrophic cardiomyopathy. J Am Coll Cardiol. 2009;54(3):204.

In HOCM, usually only the septal wall has asymmetrical hypertrophy, as shown in Figure 15-15, and it obstructs the left ventricular outflow tract (LVOT). Hypertrophy of the apical wall alone is rare and called Yamaguchi disease.25 The LVOT reduces the amount of blood leaving the LV and increases the workload of the LV.23,25 MR occurs in HOCM when the leaflets of the mitral valve are pulled anteriorly during systolic ejection, systolic anterior motion (SAM) of the mitral valve.23,25 The pressure gradient falls below the valve (subvalvular) and changes (dynamic) as the flow increases through the narrowed LVOT. As the LVOT obstruction increases, the velocity of the blood passing through it increases (the Venturi effect). The increased velocity of the blood decreases the fluid pressure and causes an increase in the SAM of the mitral valve. This worsens the MR.23 The gradient increases if the preload of the LV is low, or there is an increase in contractility. Obstruction can exist at rest or can be brought on by provocative maneuvers (i.e., Valsalva, exercise, sudden upright position, amyl nitrite).23 In hypertrophic nonobstructive cardiomyopathy, the hypertrophied muscle is not large enough to cause any obstructions.26 Symptoms are not always present. The symptoms of HOCM correlate with the severity of the MR and LV diastolic dysfunction, not the magnitude of the LVOT obstruction.23 Box 15-6 includes the signs and symptoms of HOCM. As the disease progresses, the LV dilates, and it may progress to DCM and HF. HOCM is sometimes the cause of sudden cardiac death (SCD) at

BOX 15-6 Signs and Symptoms of HOCM AF Chest discomfort Chest pain Dyspnea (most common) Fatigue Leg edema Orthopnea

Palpitations Paroxysmal nocturnal dyspnea Pre-syncope or syncope Stroke SCD Ventricular tachycardia Ventricular fibrillation

an early age because the heart is unable to increase cardiac output during strenuous exertion.23 This leads to syncope or sudden death. The carotid pulse in HOCM has a brisk upstroke during early systole and decreases due to the obstruction.23 Lack of HF reveals clear lungs on auscultation and normal jugular venous pressure. Cardiac assessment reveals a forceful, sustained, and laterally placed point of maximal impulse. An atrial gallop, S4 heart sound, is present. Auscultation along the upper left sternal border reveals a harsh, crescendo-decrescendo systolic murmur. A Valsalva maneuver reduces venous return, resulting in decreased preload. This increases the systolic murmur heard in HOCM.23 Following a history and physical exam, the tests listed in Table 15-10 confirm the HOCM diagnosis. The lifestyle modifications used in the treatment of HCM include the avoidance of the triggers that cause symptoms such as strenuous activity, Valsalva

The Cardiomyopathies

TABLE 15-10 Diagnostic Tests for HOCM Test

Uses

Blood work

Increased BNP indicates HF

CXR

Identify LVH

ECG

LVH • R wave > 12 mm in Lead I • R wave > 11 mm in Lead aVL • R wave > 20 mm in Lead aVF • Height of S wave in V1 or V2 + Height of R wave V2 or V6 >35 mm LAE • M-shaped P waves in Lead II • Biphasic P waves in Lead V1

Echocardiogram

Identifies the location of hypertrophy (Figure 15-16) Measures wall thickness Identifies the degree of LVOT Identifies the presence of SAM

Transesophageal echocardiogram (TEE)

Used if echocardiogram is inconclusive

CMRI

Determines location, pattern, and extent of myocardial fibrosis

Cardiac catheterization

Reserved for uncertain diagnosis using other tests Identifies and verifies dynamic pressure gradient across the LVOT

Genetic testing

Establishes or excludes HOCM Identifies specific mutation

maneuvers, and competitive athletics. To avoid underfilling of the LV and reduce LVOT obstruction, patients need to be kept well hydrated.23 The medications used in the treatment of both HOCM and HCM without outflow obstruction appear in Table 15-11. Several medications worsen the LVOT obstruction. They include those drugs that decrease afterload, including ACE inhibitors, ARB, and nitrates. Drugs that have positive inotropic effects increase the force of myocardial contraction and the LVOT gradient. These drugs include digoxin, dopamine, dobutamine, and norepinephrine.23 The indication for surgical intervention occurs when the symptoms do not respond to pharmacologic treatment, and there is a resting pressure gradient ≥ 50 mm Hg between the LV apex and the LVOT. This surgical intervention is a septal myomectomy that cuts away the septal wall to open the LVOT.23 A less-invasive and alternative intervention is percutaneous alcohol septal ablation (ASA). This procedure involves injecting a small amount (1–3 mL) of desiccated ethanol into the artery feeding the hypertrophied septum. The alcohol causes a MI localized to the septal wall, which results in localized muscle death. As the muscle becomes necrotic, it shrinks (this may take weeks) and the LVOT gradient decreases.23 Risk factors that may worsen HCM include strenuous exercise that increases afterload (i.e., heavy weight lifting/training), a family history of HCM, increased ventricular wall thickness, along with the presence of certain genetic mutations in certain individuals.23 Complications from HCM are arrhythmias, obstructed blood flow, DCM, mitral valve problems (MR), HF, and SCD.27

I

aVR

V1

V4

II

aVL

V2

V5

III

aVF

V3

V6

II

FIGURE 15-16  ECG of HOCM with LVH.

409

410

CHAPTER 15  Heart Failure Mortality is affected by the age at which the symptoms appear and is higher in children than in adults (1–3%). Mortality is higher when there are frequent non-sustained ventricular tachycardia, syncope, or resuscitation following SCA. HF does not always occur. The prognosis is worse for young people who have a family history of sudden death and people older than 45 years with chest pain or exertional dyspnea.28

Restrictive Cardiomyopathy Restrictive cardiomyopathy (RCM) is the least common

cardiomyopathy in the United States. RCM is due to abnormally rigid (but not necessarily thickened) ventricles with impaired diastolic filling but usually normal, or TABLE 15-11 Medications for HCM Medications

Use in HCM

Beta-blockers

• Reduces myocardial oxygen demand by slowing the heart rate and contraction force • Decreases contraction force—reduced LVOT gradient during exercise

Calciumchannel blockers

• Second-line therapy for those in whom betablockers failed • A negative chronotropic effect, which leads to increased diastolic relaxation time (thus increasing preload)

Type IA antiarrhythmic drug

• AF in HCM • Negative inotropic effects improve diastolic function

near-normal, systolic function.29 This condition results from either fibrosis or scarring of the endo-myocardium or infiltration of the myocardium by an abnormal substance.14 Causes of RCM appear in Figure 15-17. Genetic diseases can also cause RCM, notably Fabry disease, Gaucher disease, or hemochromatosis.30 RCM causes endocardial thickening or myocardial infiltration in one, typically the left, or both ventricles. This thickening may result in mitral valve regurgitation or tricuspid valve (TV) regurgitation. If the sinoatrial (SA) node or atrioventricular (AV) node is affected, various grades of AV blocks may occur.29 The main hemodynamic consequence of RCM is a result of the noncompliant ventricles. The ventricles become rigid, impairing diastolic filling. This causes high filling pressure that leads to pulmonary and systemic hypertension.30 If the myocardium cannot compensate through hypertrophy, systolic dysfunction occurs.30 Symptoms result from the inability of the myocardium to relax and distend. They include exertional dyspnea, orthopnea, and fatigue. If the RV is affected, peripheral edema will occur.30 Atrial and ventricular arrhythmias and AV blocks may occur. Angina and syncope are uncommon. Signs and symptoms closely mimic those of constrictive pericarditis (see the “Constrictive Pericarditis” section below).30 Palpitation and auscultation reveals a low-volume and rapid carotid pulse, pulmonary crackles, and pronounced neck vein distention. S3 and S4 heart sounds are present.30 The fibrous changes to the heart may affect the chordae tendineae or the shape of the ventricle, and this causes mitral or TR.30

Restrictive

Endomyocardial diseases • Endomyocardial fibrosis • Loeffler’s disease • Metastatic tumors • Radiation therapy

Infiltrative diseases • Amyloidosis • Fatty infiltration • Gaucher disease • Hurler syndrome • Sarcoidosis

Cardiomyopathy

Storage diseases • Fabry disease • Glycogen storage disorder - type 3 • Hemochromatosis

Noninfiltrative diseases • Idiopathic • Scleroderma

FIGURE 15-17  Causes of restrictive cardiomyopathy. Modified from Lee C, Dec G, Lilly L. The Cardiomyopathies. In: Lilly L, ed. Pathophysiology of Heart Disease. 5th ed. Philadelphia: Lippincott Williams & Wilkins; 2011:257.

The Cardiomyopathies

TABLE 15-12 Summary of the Cardiomyopathies DCM

HCM

RCM

Ventricular morphology

Dilated LV usually without hypertrophy

Marked hypertrophy, often asymmetric

Fibrotic or infiltrated myocardium

Etiologies

Genetic, infectious, alcoholic, peripartum

Genetic

Amyloidosis, hemochromatosis, scleroderma, radiation therapy

Symptoms

Fatigue, weakness, dyspnea, orthopnea, paroxysmal nocturnal dyspnea

Dyspnea, angina, syncope

Dyspnea, fatigue

Physical exam

Pulmonary crackles, S3; if RV failure present: JVD, hepatomegaly, peripheral edema

S4, if outflow obstruction present: systolic murmur loudest at left sternal border, accompanied by MR

Predominantly signs of RV failure: JVD hepatomegaly, peripheral edema

Pathophysiology

Impaired systolic contraction

Impaired diastolic relaxation; LV systolic function vigorous, often with dynamic obstruction

“Stiff” LV with impaired diastolic relaxation but usually normal systolic function

Cardiac size on CXR

Enlarged

Normal or enlarged

Usually normal

Echocardiogram

Dilated, poorly contractile LV

LVH, often more pronounced at septum, systolic anterior movement of MV with MR

Usually normal systolic contraction, speckled appearance in infiltrative disorders

Medications to control symptoms

Diuretic ACE inhibitor Angiotensin II receptor blocker Beta-blocker Amiodarone

Beta-blocker Calcium-channel blocker Type IA antiarrhythmic agent

Diuretic Oral anticoagulant

Devices/surgery

ICD CRT RVAD LVAD

ICD Septal myomectomy Percutaneous septal ablation

Septal myomectomy ICD

Reproduced with permission from Lilly LS & Harvard Medical School. (2016). Pathophysiology of heart disease: A collaborative project of medical students and faculty.

The tests used to diagnose RCM include ECG, CXR, and echocardiogram. An ECG may show low voltage with ST-segment and T-wave abnormalities, pathologic Q waves (not from a previous MI), and HOCM. In many cases, a CXR shows a normal-sized heart; however, it may reveal a small heart, or in the late stages, it may be enlarged. Appropriate tests should be done to check for amyloidosis, iron, or hemochromatosis, which are common causes of RCM.30 The medications used in RCM are to treat the symptoms, not the disease. Diuretics can be given to reduce pulmonary congestion. Caution is needed not to compromise preload. If preload becomes too low, the noncompliant ventricles cannot maintain cardiac output.30 In cases with elevated heart rates, beta-blockers or rate-limiting calcium-channel blockers may be used cautiously in low doses. Medications that lower afterload may cause hypotension and are not helpful.30

Oral anticoagulants are used to control intraventricular thrombus formation in some individuals.14 Performing septal myomectomy/ablation may ­improve some symptoms. Pacemakers may be helpful in older patients, and ICDs may help younger patients at higher risk of SCD. Transplantation is not recommended because the disorder may recur in the transplanted heart.30 Risk factors for RCM include a family history of cardiomyopathy and of other types of heart disease, CHD, obesity, diabetes, high BP, and alcoholism.31 Complications from RCM are HF, mitral valve regurgitation, arrhythmias, pulmonary edema, and heart attacks.31 Because most of the treatments available are for treating the symptoms, the prognosis of RCM is poor.30

Summary of the Cardiomyopathies A summary of all the cardiomyopathies is in Table 15-12.

411

412

CHAPTER 15  Heart Failure

3. True or False: The etiology of HCM is genetic.

located between the RV and the pulmonary artery (PA). Figure 15-18 shows the circulation of blood through the chambers and valves of the heart. These valves prevent blood from flowing backward and causing systemic venous congestion or pulmonary congestion. Also, they help direct the blood forward. A stenotic valve does not open all the way and will restrict forward blood flow. If the valve is incompetent, this will allow the blood to flow backward, and this is regurgitation.4

4. True or False: Ischemia can cause HCM.

Aortic Insufficiency (Aortic Regurgitation)

KNOWLEDGE CHECK QUESTIONS 1. True or False: The anatomic appearance and abnormal physiology of the RV is the basis for cardiomyopathy classification. 2. True or False: The hallmark of DCM is ventricular dilation.

Aortic insufficiency (AI) is the inability of the aortic

valve to close properly, allowing the blood to regurgitate back into the LV during diastole. This regurgitation increases the preload and leads to volume overload.29 The results are LV dilatation and HF. Causes of AI include rheumatic fever, infective endocarditis, collagen vascular diseases, degenerative aortic valve disease, trauma, postsurgical (including post-transcatheter) aortic valve

Valvular Heart Diseases The four valves in the heart are the mitral, tricuspid, pulmonary, and aortic. The mitral valve sits between the LA and the LV, the TV is located between the RA and the RV, the aortic valve is located between the LV and the aorta, and the pulmonary valve is

Superior vena cava Right pulmonary artery

Brachiocephalic artery

Left common carotid artery

Left subclavian artery Aorta Left pulmonary artery Left pulmonary veins

Right pulmonary veins

Left atrium Atrioventricular (mitral) valve Left ventricle

Right atrium Atrioventricular (tricuspid) valve

Septum

Right ventricle Inferior vena cava

Superior vena cava Right atrium Inferior vena cava

Tricuspid valve

Rest of body

FIGURE 15-18  Circulation of blood through the heart.

Right ventricle

Aorta

Pulmonary artery

Lungs

Left ventricle

Left atrium

Mitral valve

Valvular Heart Diseases

TABLE 15-13 Scale Used to Quantify Valvular Insufficiency Scale

Explanation

Mild (1+)

A small amount of blood/contrast enters the LV during diastole and clears with each systole.

Moderate (2+)

Blood/contrast enters the LV with each diastole, but the LV chamber is less dense than the aorta.

Moderately severe (3+)

The LV chamber is equal in density to the ascending aorta.

Severe (4+)

Complete, dense opacification of the LV chamber occurs on the first beat, and the LV is more densely opacified than the ascending aorta.

replacement, or dilatation of the aorta.29 An angiogram of the ascending aorta quantifies the regurgitant flow. An echocardiogram quantifies the regurgitant flow using the scale shown in Table 15-13. AI causes the aortic diastolic pressure to decrease and the systolic pressure to increase. This widens the pulse pressure, the difference between aortic systolic and diastolic pressure.29 The severity of the AI is quantified by determining the diastolic pressure gradient between the aorta and the LV and measuring the diastolic valve area.29 The effect AI has on an individual depends on whether it is acute or chronic. In acute AI, there is a high mortality rate because the LV does not have time to adapt to the volume overload. If not treated promptly it will quickly progress from pulmonary edema to refractory HF and cardiogenic shock.29 In chronic AI, the LV has time to adapt and will dilate to handle the volume overload. Consequently, this will cause a dilated LV with contractility.29 The symptoms of acute AI are the same symptoms listed in the DCM section. These symptoms include tachycardia, cool extremities, lung crackles, low BP, and cardiogenic shock. Because acute AI has a rapid onset, the heart is unable to compensate and will result in an emergency. Upon auscultation, the first heart sound (S1) is usually absent or diminished due to equal diastolic pressure in the LV and AO. There is usually a third heart sound (S3 or ventricle gallop). There will be a mid-to-late diastolic rumble heard at the apex (Austin Flint murmur).32 Symptoms of chronic AI may not become apparent for a long time. By the time symptoms do become apparent, the heart is usually severely affected.32 The symptoms can be inconspicuous and are the same as DCM. An abnormal aortic valve is more susceptible to endocarditis. The presence of endocarditis causes additional signs and symptoms, such as fever, anemia, weight loss, and embolic phenomena.32 As the disease

progresses, the PMI becomes enlarged, sustained, increased in amplitude, and displaced downward and laterally.32 The cardiac sounds include a loud sharp or slapping second heart sound (S2), caused by increased elastic aortic recoil, and a high-pitched decrescendo diastolic murmur is heard at the third or fourth left parasternal intercostal space.32 If infectious endocarditis causes the AI blood tests, identify the causative organism. Also, renal and liver function tests are necessary to check for medication clearance.33 When AI is a result of infectious endocarditis, early surgical intervention is appropriate. With aortic dissection, emergent intervention is warranted.33 Suspected AI requires an echocardiogram to confirm it and establish a baseline of the regurgitant flow.33 If previous echocardiograms have documented AI, then regular echocardiograms quantify any changes in the regurgitant flow. Using echocardiogram will help to determine the information listed in Box 15-7. A CXR may show structural abnormalities like aortic dilation, prosthetic valve dislodgement, aortic valvular calcification, or cardiomegaly.33 Radionuclide imaging determines the regurgitant fraction and the LV/RV stroke volume ratio.33 Cardiac catheterization is optional in AI. But it can provide valuable clinical information when surgery is being contemplated. The catheterization will allow for coronary artery anatomy evaluation and the regurgitant flow through the aortic valve.33 An aortic angiography quantifies the regurgitant flow using the scale in Table 15-13.33

BOX 15-7 Information Obtained from an Echocardiogram for AI 1. Proper time to replace the valve 2. Structure and morphology of the leaflets ­(bi-leaflet vs. tri-leaflet, flail, thickening) 3. Presence of vegetation or nodules 4. Severity of AI 5. Regurgitant volume 6. Orifice area 7. Premature closure of the mitral valve 8. Opening of the aortic valve 9. Aortic dilation 10. Aneurysm 11. Dissection 12. LV structure and function 13. LVH and dilation 14. EF 15. End-systolic dimension

413

414

CHAPTER 15  Heart Failure Cardiac CT scanning and magnetic resonance imaging (MRI) are not widely recognized as a diagnostic tool for AI. However, there is growing support in the literature for the potential clinical use of these imaging techniques. Electrocardiographic findings are nonspecific but may include LVH (see the “Hypertrophic Cardiomyopathy” section), left-axis deviation, LAE, LV volume overload pattern, and LV conduction defects.33 When the AI is from aortic root dilatation, an ARB medication may be used. This class of medication slows the progression, especially if it is accompanied (concomitant) by hypertension.33 Surgery is appropriate when the AI is severe and symptoms or evidence of LV dysfunction is present. Identification of LV dysfunction includes EF < 50%, LV end-systolic dimension > 50–55 mm, or LV enddiastolic dimension > 65–75 mm. When the ascending aorta is dilated > 55 mm, surgery is considered sooner.33 Currently, only surgical options for aortic valve replacement exist. AI replacement involves open-heart surgery similar to coronary artery bypass surgery. If surgery is not an option, the patient needs the same treatment as HF from DCM. AI is a contraindication for the use of an intra-aortic balloon pump because the pump worsens the AI.33 Risk factors for AI include congenital heart defects (having one or two leaflets instead of three), old age, being male, Marfan syndrome (an inherited disorder that affects connective tissue), high BP, and autoimmune diseases.34 The complications from AI are abnormal heart rhythms, HF, and infection in the heart.35 Early valve replacement produces the best long-term results. Replacing the valve when AI is mild or moderate will result in a 10-year survival rate of 80–95%. If AI is severe and HF is not present, long-term prognosis is good. However, if the AI is severe, and HF symptoms are present, the long-term prognosis is poor.36 A summary of AI can be found in Table 15-14.

Aortic Stenosis In aortic stenosis (AS), the opening between the LV and the AO becomes stenotic. Left ventricular emptying becomes impaired because of the increased outflow resistance.37 AS leads to an increase in LV systolic pressure and causes a mean pressure gradient of at least 10 mm Hg. AS is the most common of the valvular heart diseases. Calcified AS and congenital bicuspid AS account for the majority of AS cases.37 Approximately 25% of the population over 65 years old with a normal valve at birth will develop mild thickening, or calcification, or both without restricted leaflet movement (i.e., aortic sclerosis). AS can lead to AI (see the “Aortic Insufficiency (Aortic Regurgitation)” section).37 In AS, the LV must generate a higher pressure to eject the blood through a narrowed opening, which causes a pressure overload problem.31 If the mitral

TABLE 15-14 Summary of AI Description

The inability of the aortic valve to close properly, allowing blood to regurgitate back into the LV during diastole

Etiology

Rheumatic fever Infective endocarditis Collagen vascular diseases Degenerative aortic valve disease Trauma Postsurgery (including post-transcatheter aortic valve replacement) Dilatation of the aorta

Clinical manifestations

Same as DCM Tachycardia Cool extremities Pulmonary crackles Hypotension Cardiogenic shock

Diagnostic tests

CXR Cardiac catheterization Aortic angiography ECG

Medical treatment

AI from aortic root dilatation using ARB medication

Surgical treatment

Aortic valve replacement via open-heart surgery

Data from Novara GM. Aortic Valve Disease.: Cleveland Clinic Center for Continuing Education. http://www.clevelandclinicmeded.com/medicalpubs /diseasemanagement/cardiology/aortic-valve-disease/

valve is intact, the lungs will not be affected. However, if there is MR, there will be an increase in pulmonary pressures.37 As the LV works harder to eject the blood, the cells of the LV increase in size (LVH). The LVH is a compensatory mechanism and increases the systolic pressure to maintain the stroke volume and cardiac output. Years may pass without any symptoms. The LVH will eventually lead to diastolic dysfunction and LV dilatation.37 As the LV becomes larger, it requires more oxygen. Eventually the cardiac output will not be able to meet the needs of the heart, and myocardial ischemia will occur (see Ischemic Heart Disease in Chapter 22).37 Symptoms of AS include angina, syncope, or HF.37 Cardiac auscultation reveals a harsh systolic murmur, which will be loudest at the base of the heart and radiate to the carotids. Obesity, low cardiac output, and chronic lung disease mask the sound of this murmur.38 Other findings from an examination are a single (pulmonic) component of the second heart sound, left ventricular apical impulse with an S4 heart sound, and a low-volume carotid pulse in younger patients; changes in arterial compliance often mask these findings in older adults.38 An echocardiogram is the gold standard for the diagnosis of AS. An echocardiogram will identify a stenotic aortic valve and its possible causes. It will also quantify

Valvular Heart Diseases

TABLE 15-15 AS Classifications37 Scale

Valve Area (cm2)

Mean Pressure Gradient (mm Hg)

Mild

1.5–2.0

5 mm Hg if severe), thickened leaflets with reduced movement, and RA enlargement.64 An ECG may show RA enlargement with tall peaked P waves in inferior leads and V1. The superior vena cava and RA will appear enlarged on a CXR. Blood work will reveal elevated liver enzymes due to hepatic congestion.64 A cardiac catheterization is usually not performed; however, if performed, it will show elevated RA pressure with a slow fall in early diastole and a diastolic pressure gradient across the TV.64 Because there is not much evidence to show that valve replacement is beneficial, the valve is rarely replaced; medical treatment will include a low-salt diet, diuretics, and aldosterone antagonists. If the symptoms worsen, then the valve needs replacement.64 Risk factors for TS include Group A streptococcal pharyngitis, metastatic carcinoid tumors, artificial TV, intravenous drug use, pacemaker/defibrillator leads crossing TV orifice, and genetic predisposition and environmental factors.65 Complications from TS are right atrial enlargement, right-sided HF, stroke, arrhythmias, or blood clots.66 The prognosis of TS is usually good, but it is dependent on the progression of the underlying causes, other related heart abnormalities, and associated arrhythmias (Table 15-24).67

KNOWLEDGE CHECK QUESTIONS 1. True or False: AI leads to LV volume overload. 2. True or False: The most common valvular heart disease is MS. 3. True or False: DCM can cause MR. 4. True or False: The S1 heat sound is accentuated with MS. 5. True or False: Chronic severe pulmonary insufficiency causes left-sided HF. 6. True or False: PS is a component of Tetralogy of Fallot.

Congenital Heart Disease A congenital heart disease is due to a structural and functional problem within the heart that has been present since birth. VSDs and ASDs are the most common types of congenital heart defects that can go undetected for years if small enough.

Ventricular Septal Defects A ventricular septal defect (VSD) is the abnormal opening in the intraventricular septal wall6 (Figure 15-25). The incidence of VSDs is 1.5–3.5 per 1,000 live births.68 The size, and not the location, of the VSD dictates some hemodynamic changes and symptoms. A VSD allows communication between systemic and pulmonary circulations. The blood flow through the VSD typically moves from the LV (high pressure) to the RV (low pressure), causing a left-to-right shunt (Figure 15-27).

TABLE 15-24 Summary of TS Description

Obstruction of blood flow from the RA to the RV during diastole due to stenosis

Etiology

Rheumatic heart disease (90% of cases)

Clinical manifestations

JVD Abdominal distension Hepatomegaly

Diagnostic tests

Echocardiogram ECG CXR Liver enzymes

Medical treatment

Low-sodium diet Diuretic Aldosterone antagonist

Surgical treatment

Surgical valve replacement

FIGURE 15-27  Ventricle septal defect.

Congenital Heart Disease The smaller the VSD, the more resistance flows through it, resulting in less shunted blood. Small VSDs are restrictive VSDs because the defect itself offers more resistance to flow than the pulmonary or systemic vasculature.68 Large VSDs allow significant shunting to occur. A fetus with a large VSD has little shunting because both pulmonary and SVR are equivalent. After birth, however, the normal fall in pulmonary vascular resistance (PVR) causes increasing left-to-right shunting through a large VSD. Because no physical resistance to blood flow exists with a large VSD, they are nonrestrictive VSDs.68 A small VSD may not produce symptoms and may have an excellent long-term prognosis, even without treatment. A large VSD requires a trial of a medical therapy to manage symptomatic CHF.32 Many VSDs may become smaller over time. However, uncontrolled CHF accompanied by a failure to thrive and recurrent respiratory infections are indications of surgical repair. Neither the age nor the size of the patient is prohibitive when considering surgery.68 The pathophysiologic effects of a VSD result from a large left-to-right shunt. The hemodynamic consequences of a left-to-right shunt are volume overload of the RV, pulmonary circulation, LA, and LV. Initially, the increased blood return to the LV augments stroke volume (via the Frank–Starling mechanism), but over time, the increased volume load can result in chamber dilatation, systolic dysfunction, and symptoms of HF.68 The volume overload in the RV increases pressure and may lead to pulmonary vascular disease.69 The presence of pulmonary vascular disease may change the shunt to a right-to-left shunt (Eisenmenger syndrome).69 A right-to-left shunt will send deoxygenated blood directly to the systemic arterial circulation, causing systemic hypoxemia and cyanosis.68 The size of the VSD and left-to-right shunt influences the patient signs and symptoms.70 The large VSDs are typically found early and repaired. If an adult has a VSD, it is usually small in size.70 Small VSDs are typically asymptomatic or mild, with no murmur heard during auscultation. Newborns with moderate VSD may sweat excessively during feedings due to increased sympathetic tone. The increased cardiac output needed for feeding fatigues the infant, resulting in failure to thrive and frequent respiratory infections. Symptoms become more apparent as the PVR decreases.70 The symptoms of a large VSD will be similar to those of a moderate VSD, but with increased severity. A delayed decrease in PVR will delay the symptoms. Cardiac auscultation detects a VSD over the lower left sternal border. The sound heard is related to the oxygenated blood “swishing” through the hole or VSD into the RV (holosystolic murmur).71 The smaller the defect, the louder the holosystolic murmur. This occurs because smaller holes create more turbulent flow.

When suspected, a VSD is confirmed by Doppler echocardiogram. The echocardiogram quantifies the amount of blood shunted and the pulmonary pressure. A CXR may show an enlarged heart, pulmonary congestion, or alveolar edema.71 An ECG may show LVH or RVH (see “Hypertrophic Cardiomyopathy” section). With RVH, there is a concern with PH and immediate intervention is necessary. A right and left heart catheterization may be necessary to obtain right heart, left heart, and pulmonary pressures.71 By age 2, at least 50% of small and moderate-sized VSDs undergo sufficient partial or complete spontaneous closure to make intervention unnecessary.68 Even after this type of closure, long-term follow-up is required.72 An untreated VSD can lead to pulmonary vascular disease and HF. If HF develops, it is treated with the same drugs used for DCM. Ultimately, a large VSD will need to be repaired surgically. Two types of surgeries are available to correct a VSD: the intracardiac technique and the transcatheter technique.72 The surgical procedure is open-heart surgery, using the heart–lung bypass machine. The surgery to repair a VSD usually involves placing a patch to close the hole.73 The patch is a strong woven fabric made of Gore-Tex or Dacron. During the healing process, the heart’s cells will grow over the patch, making it part of the body.73 The transcatheter approach, currently in clinical trials, involves surgical instruments passed through catheters inserted into the body. To close the hole, a disk is deployed through the catheter.72 Risk factors for VSD include Asian heritage (Asians are more likely to be born with VSD), family history of congenital heart disease, and other genetic disorders, such as Down syndrome.74 Complications from VSD include aortic regurgitation, Eisenmenger syndrome, RV outflow tract obstruction, discrete fibrous sub-AS (a fibrous lesion obstructing the LVOT), and infective endocarditis.75 Children with small VSDs, who are asymptomatic, have a good prognosis. However, the outcome of medical therapy for children with moderate or large VSDs varies. Many infants show improvement between the ages of 6 and 24 months. Surgical intervention carries less than a 2% mortality rate for isolated VSDs (Table 15-25).68

Atrial Septal Defect Atrial septal defects (ASD) are persistent openings

in the heart between the left and the right atria, as seen in Figure 15-28. The opening can occur anywhere along the atrial septum, but most commonly occurs in the area of the foramen ovale. This is an ostium secundum defect. Its development is due to inadequate formation of the septum secundum, excessive resorption of the septum primum, or a combination.

425

426

CHAPTER 15  Heart Failure

TABLE 15-25 Summary of VSDs Description

Abnormal opening in the intraventricular septal wall

Etiology

Congenital defect

Clinical manifestations

Small VSD—holosystolic murmur Large VSD—signs and symptoms of CHF and pulmonary vascular disease

Diagnostic tests

Doppler echocardiogram Right and left heart catheterization

Medical treatment

Same drugs used for DCM

Surgical treatment

Open-heart surgical repair with a Gore-Tex or Dacron patch

Sinus venosus defect Ostium secundum defect

LA RA

Ostium primum defect

LV RV

FIGURE 15-28  ASD locations.

Less common ASDs include the ostium primum defect located in the lower right portion of the interatrial septum (a defect of the endocardial cushion tissue) and the sinus venosus defect located in the high RA (is an error in the incorporation of the sinus venosus chamber into the RA).69 The pathophysiology in all three ASDs is the same. The flow through the defect will occur during both systole and diastole, and is mostly a left-to-right shunt. The majority of the shunted blood occurs during diastole. It is at this time that the blood can flow through the AV valve to the ventricles, or through the defect.69 The direction of flow across the ASD during diastole is determined by the compliance and the capacity of the two ventricles. The LV has thicker walls than the RV and, therefore, is less complaint, which will favor a left-to-right shunt.69 If the RV develops an increase in afterload due to increasing PVR, it will become hypertrophied and less compliant. Consequently, there will be a decrease in the left-to-right shunt. The more

hypertrophied the RV becomes, the less the left-to-right shunt will be. A continued RV compliance reduction will shift the shunt to a right-to-left shunt (Eisenmenger syndrome).69 The size of the ASD will determine the volume of blood shunted. In a large ASD, there is little or no resistance to flow. Blood flow across the defect in diastole is determined entirely by the relative properties of the ventricles. A small ASD is considered a restrictive defect. Blood flow is limited by the resistance of the ASD itself, no matter how large the difference in ventricular compliance.69 Children with an ASD are not always symptomatic because the myocardium is compliant and of normal size. As people with an ASD age, the myocardium hypertrophies and becomes less compliant. Symptoms usually appear between the ages of 40 and 50.69 Because the shunt is between the left and the right atria, the LV receives less blood. This reduces preload, leading to a reduction in contractility and systemic cardiac output. There is an increase in pulmonary cardiac output, causing pulmonary volume overload. Less oxygenated blood going into the systemic circulation causes shortness of breath on exertion, the most common symptom.69 The increased volume in the RA and RV causes the myocardium to stretch, resulting in atrial arrhythmias, usually the first sign of an ASD. A young adult presenting with atrial arrhythmia needs evaluation for dilatation of the RA and RV and evidence of an atrial-level shunt.69 If dilation of the RA and RV exist, a CXR will show cardiomegaly with a prominent PA and pulmonary vascular markings in the lung fields.76 An ECG will vary depending on the location of the septal defect. A secundum ASD may show normal sinus rhythm, right-axis deviation, an interventricular conduction delay, or right bundle branch block.76 An ostium primum ASD will show left-axis deviation, an interventricular conduction delay, or right bundle branch block.76 An echocardiogram will confirm the diagnosis of ASD. Doppler studies can demonstrate flow across the atrial septum. They typically show a biphasic pattern with a small right-to-left shunt at the beginning of systole. Using a contrast agent during the echocardiography provides confirmation of the shunt direction (right to left or left to right).76 If an echocardiogram is inconclusive, a TEE can provide confirmation.76 MRIs can identify the size and position of an ASD. The MRI, however, does not detect small ASDs. Advantages of MRI use are visualization and quantification of the RV size, volume, and function and evaluation of the systemic and pulmonary venous return.76 Asymptomatic ASDs do not require medical therapies. Symptomatic ASDs require medical treatment

Pericardial Diseases that include anticoagulant agents, antiarrhythmic agents, and diuretic agents (for CHF symptoms). ASD repair either surgically or percutaneously is the most effective treatment.67 The surgical procedure is considered open-heart surgery and uses autologous pericardium, synthetic patches made of polyester polymer (Dacron), or polytetrafluoroethylene (PTFE) to close the ASD.67 An ostium primum ASD is the most complicated and difficult to repair. Placing the patch is difficult and must be attached to the septum at the juncture of the mitral and TVs. The mitral valve may also need to be repaired, including closure of the cleft mitral leaflet and, possibly, annuloplasty.67 A sinus venosus ASD may cause one or more of the PV to drain into the RA (anomalous pulmonary venous return). During the repair of the sinus venosus ASD, the patch must be placed so as to close the ASD and ensure the anomalous pulmonary venous drainage is diverted into the LA. If not done correctly, the pulmonary venous return will be compromised and may lead to pulmonary venous hypertension.67 Transcatheter ASD closure is associated with fewer complications, shortened hospitalization, and reduced need for blood products. Catheters with the ASD patch are placed through a femoral vein and deployed like an umbrella to seal the septal defect. The transcatheter devices work best for centrally located ostium secundum ASDs and for a patent foramen ovale. Prior to the procedure, a TEE determines the static diameter of the ASD. During the procedure, the diameter is measured using a sizing balloon; a balloon is inflated until no flow is visible through the defect using TEE.67 As with VSDs, ASDs are birth defects. They can occur alone or with other genetic problems, such as Down syndrome.77 The risk of congenital ASDs is increased by the presence of certain conditions before or during pregnancy. These conditions include rubella, drug, tobacco or alcohol use, diabetes, lupus, obesity, and phenylketonuria (PKU).77 If an ASD is not repaired, the extra blood being shunted through the hole can lead to complications such as right HF, arrhythmias, stroke, and PH.78 The mortality rate for ASD is less than 1%. The morbidity for ASD is low if it is repaired before age 45, if HF has not developed, and the pulmonary pressure is less than 60 mm Hg. When a sinus venosus ASD is surgically repaired, the mortality and morbidity are low, and clinical improvement occurs regardless of the patient’s age at surgery. Whether the ASD is repaired surgically or percutaneously, the long-term results are similar. More arrhythmias are seen following surgical repair than percutaneous repair. However, there are more embolic events with the percutaneous repairs (Table 15-26).67

TABLE 15-26 Summary of ASDs Description

Persistent opening in the heart between the left and the RA

Etiology

Congenital Maternal exposure to rubella, smoke, drugs, alcohol Maternal diabetes, lupus, obesity, or PKU

Clinical manifestations

Small ASD—asymptomatic Large ASD—CHF symptoms, myocardial hypertrophy

Diagnostic tests

CXR ECG Doppler echocardiogram TEE MRI

Medical treatment

Anticoagulant agents Antiarrhythmic agents Diuretic agents

Surgical treatment

Open-heart surgical repair with polyester polymer (Dacron) patch or PTFE patch Transcatheter closure with patch

KNOWLEDGE CHECK QUESTIONS 1. True or False: The location of the VSD determines the hemodynamic changes. 2. True or False: A holosystolic murmur is caused by a VSD. 3. True or False: There are three types of ASDs. 4. True or False: Small ASDs are usually asymptomatic.

Pericardial Diseases The pericardium is a double-layer fibroelastic sac that contains the heart and the roots of the great vessels. This sac contains a thin layer of pericardial fluid, which provides lubrication for movement of the heart and protection against infection. Pericardial diseases may occur as a component of other systemic disorders or as an isolated disease.

Pericarditis Pericarditis is caused by inflammation of the peri-

cardium, often with fluid accumulation (pericardial effusion). Acute pericarditis is a rapidly developing inflammation of the pericardium. The pericardium is a two-layered sac that surrounds the heart. The visceral

427

428

CHAPTER 15  Heart Failure

BOX 15-12 Causes of Acute Pericarditis Idiopathic ƒƒ Noninfectious ƒƒ Drug induced yy Hydralazine {{ Procainamide Connective tissue diseases yy {{ Rheumatoid arthritis {{ Systemic lupus erythematosus {{ Systemic sclerosis Cancer yy {{ Breast cancer {{ Leukemia {{ Lung cancer Post-MI yy Radiation therapy yy Infectious ƒƒ Bacteria yy {{ Pneumococci {{ Staphylococci {{ Tuberculosis Viral yy {{ Coxsackie B {{ Echovirus {{ Influenza Fungal yy {{ Blastomycosis {{ Candidiasis {{ Coccidioidomycosis {{ Histoplasmosis {{

pericardium contains a single layer of mesothelial cells, which adhere to the outer wall of the heart. The visceral pericardium reflects back on itself over the origin of the great vessels and joins with a tough, fibrous outer layer, the parietal pericardium. The sac created by these two layers normally contains a thin film of pericardial fluid that decreases the friction between the layers during movement.79 There are three main causes of acute pericarditis: idiopathic, infectious and noninfectious. See Box 15-12. The most frequent symptoms of acute pericarditis are chest pain and fever. The chest pain resembles an acute MI or pulmonary infarction. Auscultation reveals a pericardial friction rub created by the movement of the inflamed pericardial layers against each other. The rub becomes louder when the patient leans forward and exhales.

TABLE 15-27 ECG Stages in Acute Pericarditis Stages

Description

I

• ST segments show upward concave elevation • The PR segments may be depressed

II

• ST segments return to baseline • T waves flatten

III

• T waves are inverted throughout the ECG • T-wave inversion occurs after the ST segments return to baseline (different pattern than acute ischemia or MI)

IV

• T-wave changes resolve

Diagnostic studies to identify acute pericarditis include the ECG, echocardiography, and blood studies. Serial ECGs may be necessary to observe any abnormalities. ECG changes in pericarditis can occur in four stages although not all stages are present in all cases79 (Table 15-27). Stage I ECG is shown in Figure 15-27. Lab tests usually show an elevated white blood cell count and elevated erythrocyte sedimentation rate. Additional tests, blood work for serum cardiac marker (troponin), and a lung scan may be required if the ECG is atypical for pericarditis.79 Troponin is often elevated in acute pericarditis due to epicardial inflammation, and therefore, it cannot be used to distinguish between pericarditis, acute infarction, and pulmonary embolism.79 An echocardiogram can identify the presence and hemodynamic consequences of pericardial effusion (Figure 15-29). Idiopathic or viral pericarditis is a self-limiting disease that usually runs its course in 1–3 weeks. Management involves rest, analgesics, and anti-inflammatory drugs. If a large pericardial effusion is present, it may require removal (pericardiocentesis).80 Subacute pericarditis is a prolongation of acute pericarditis and has the same causes.79 Constrictive pericarditis results from a rigid pericardium that does not allow the heart to stretch and fill appropriately during diastole. Its etiology includes any disorder that causes acute pericarditis. Constrictive pericarditis occurs when the visceral and parietal layers adhere to each other or to the myocardium due to marked inflammatory, fibrotic (may contain calcium) thickening of the pericardium. The stiff, thickened pericardium inhibits the normal filling of the cardiac chambers.80 The RV will quickly reach its limit, and venous return to the right heart ceases. This causes the systemic venous pressure to rise and signs of right HF to ensue.80 Impairment of LV filling decreases cardiac output. Clinically, constrictive pericarditis causes jugular veins to become more distended during inspiration

Pericardial Diseases

PR seg J I

aVR

V1

V4

aVL

V2

V5

J

II PR seg

J III

aVF

V3

V6 PR seg

FIGURE 15-29  Twelve-lead ECG of acute pericarditis showing a Stage I ECG. The ST segments in all but Leads aVR and V1 show upward

concave elevation. The T waves are depressed in Leads aVR and V1.

(Kussmaul sign) due to the inability of the right heart to accommodate the increased venous return created from the negative intrathoracic pressure generated by inspiration.80 Diagnostic testing includes ECG, lateral CXR, Doppler echocardiogram, cardiac catheterization, CT, or MRI. The ECG and echocardiography have nonspecific findings. A lateral CXR may show pericardial calcification. The Doppler echocardiography can distinguish constrictive pericarditis from RCM. Right and left cardiac catheterizations can quantify the hemodynamic changes. A CT or MRI can identify pericardial thickening greater than 5 mm.80 Treatment for severe constrictive pericarditis is a pericardial resection. Newly diagnosed patients who are hemodynamically stable and without evidence of chronic constriction may be given a 2- to 3-month trial of antiinflammatory drugs, rather than pericardial resection.79

Pericardial Effusion A pericardial effusion is an accumulation of fluid in the pericardium. Normally the pericardial sac contains between 15 and 50 mL of pericardial fluid. A larger volume of fluid may accumulate in association with acute pericarditis.80 Because the pericardium is a relatively stiff structure, the relationship between its internal volume and pressure is not linear.80 A small increase in volume in the pericardium will result in a small rise in pressure. However, when the intrapericardial volume expands beyond

a critical level, a dramatic increase in pressure is caused by the nondistensible sac.80 Three factors determine whether a pericardial effusion remains clinically silent or whether symptoms of cardiac compression are created: (1) the volume of fluid, (2) the rate at which the fluid accumulates, and (3) the compliance characteristics of the pericardium.80 A pericardial effusion can be seen on a CXR, if there is more than approximately 250 mL in the pericardium, as an enlarged cardiac silhouette. See Figure 15-30. The ECG in Figure 15-31 shows the decreased waveform voltage (small QRS complexes, P waves, and T waves). If a large effusion exists, then the QRS complexes on the ECG will alternate between large and small, known as electrical alternans. Electrical alternans occurs with variation in the cardiac position (swinging heart). An echocardiography is used to estimate the volume of pericardial fluid, identifies cardiac tamponade, acute myocarditis, and/or HF.79 Treatment for pericardial effusion includes finding and treating the cause. In effusions where the etiology is unknown, and there are no symptoms, only observation is required.79 Symptomatic and persistent pericardial effusions may require a window to be placed in the pericardium so the fluid can drain continuously. This can be done either surgically or percutaneously using a balloon pericardiotomy. A balloon pericardiotomy requires insertion of a catheter with a camera between the ribs. A puncture in the pericardial sac allows for the inflation of the balloon to create the window.79

429

430

CHAPTER 15  Heart Failure

Cardiac Tamponade Cardiac tamponade is a life-threatening condition

caused by the accumulation of pericardial fluid under high pressure, compressing the heart and severely limiting the filling of its chambers. There is a reduction in

FIGURE 15-30  An anteroposterior view of a 40-year-old man with a

hemopericardium (blood in the pericardium) and pleural effusion after pericardial tapping of 550 mL. The radiograph demonstrates the air-fluid level between the heart and the pericardium. © Santibhavank P/Shutterstock.

both stroke volume and cardiac output that may lead to hypotensive shock and death.80 Cardiac tamponade may develop from acute pericarditis, neoplasm, post-viral infection, acute hemorrhage into the pericardium from blunt or penetrating chest trauma, rupture of the LV wall post-MI, and as a complication of a dissecting aortic aneurysm. Cardiac tamponade is suspected in any patient with known pericarditis, pericardial effusion, or chest trauma who develop signs of cardiogenic shock. These signs include a low cardiac output, low systemic arterial pressure, tachycardia, and dyspnea. Pulsus paradoxus characterized by greater than 10 mm Hg inspiratory fall in systolic BP is a useful sign of tamponade.81 This sign is also present in severe asthma exacerbations and pulmonary embolism. A CXR showing cardiomegaly is common81 (Figure 15-32). The clinical manifestations of cardiac tamponade appear in Box 15-13. Cardiac tamponade is suggested by low voltage and electrical alternans on the ECG. However, these findings lack sensitivity and specificity. Echocardiography is the most useful noninvasive technique to evaluate whether pericardial effusion has led to cardiac tamponade physiology.80,81 When tamponade is suspected, echocardiography is done unless even a brief delay might be life threatening. Then pericardiocentesis is done immediately for diagnosis and treatment. On an echocardiogram, respiratory variation of transvalvular and venous flows and compression or collapse of right cardiac chambers in the presence of a pericardial effusion support the diagnosis.79 The definitive diagnostic procedure for cardiac tamponade is cardiac

I

aVR

V1

V4

II

aVL

V2

V5

III

aVF

V3

V6

II

FIGURE 15-31  Twelve lead ECG of pericardial effusion. Garcia GB, Holtz EH. 12-Lead ECG: The Art of Interpretation. Burlington, MA: Jones & Bartlett Learning; 2013.

Left Ventricular Hypertrophy If cardiac tamponade recurs after pericardiocentesis, the procedure can be repeated. In some cases, removal of part or all of the pericardium is required to prevent re-accumulation of the effusion.80

KNOWLEDGE CHECK QUESTIONS 1. True or False: Chest pain and fever occur commonly with acute pericarditis. 2. True or False: Troponin levels are normal with acute pericarditis. 3. True or False: Severe constrictive pericarditis can be controlled with medications.

FIGURE 15-32  A 21-year-old man with an enlarged cardiac

silhouette due to cardiac tamponade manifested by a systemic inflammatory disease. Reproduced with permission from Carrilho-Ferreira P, Silva D, de Jesus Silva M, André R, Varela M, Diogo A. Adult-onset Still’s disease and cardiac tamponade: a rare association. Texas Heart Inst J. 2015;42(3):277–280. doi:10.14503/thij-14-4101.

BOX 15-13 Clinical Manifestations of Cardiac Tamponade Dyspnea ƒƒ Hypoxemia ƒƒ Hypotension with pulsus paradoxus (fall of ƒƒ

>10 mm Hg in systolic BP during inspiration) JVD ƒƒ Muffled heart sounds ƒƒ Sinus tachycardia ƒƒ

catheterization with measurement of intracardiac and intrapericardial pressures, usually combined with therapeutic pericardiocentesis.80 To perform a pericardiocentesis, the patient needs to be in the supine position with the head elevated 30° from supine. Echocardiography is used to perform a detailed evaluation before pericardiocentesis to determine the ideal entry site to obtain the maximal amount of fluid.82 After using lidocaine to numb the area, a needle is inserted into the pericardium. Once in place, the fluid is aspirated into a syringe. ECG monitoring is essential for detecting arrhythmias produced when the myocardium is touched or punctured. The fluid is removed until the intrapericardial pressure falls below the right atrial pressure. If the effusion is large, a catheter will be inserted and attached to a plastic bag so the fluid can continue draining.79

4. True or False: Cardiac tamponade is a life-threatening condition requiring immediate attention.

Left Ventricular Hypertrophy Left ventricular hypertrophy (LVH) results from the

thickening of the LV walls due to chronic overload (Figure 15-33). The two most important factors contributing to the development of LVH are chronic pressure overload and chronic volume overload.38 Chronic pressure overload can be due to hypertension or AS.38 Hypertension and AS increase ventricular afterload and cause LVH as a compensatory mechanism. This results from the thickening of myocytes, causing increased ventricular wall thickness, or concentric hypertrophy. Volume overloading is an even more potent stimulus to the development of atrial dilation and LVH. MR or aortic regurgitation cause chronic volume overload. This leads to the elongation of the myocytes, enlarging the ventricle chamber and thickening the ventricle walls, or eccentric hypertrophy.83 The chronic volume or pressure overload causes the myocytes to remodel by either elongating or thickening. At first, this helps to reduce the stress on the ventricular wall and maintain the contractile force. Eventually, ventricular function declines, leading to chamber dilation out of proportion to wall thickness. As LVH continues and complications develop, symptoms appear. These symptoms include shortness of breath, exertional chest pain, palpitations, dizziness, and fainting.83 Patients with LVH due to continuous pressure or volume overload may remain in a compensatory phase with no symptoms and normal or near-normal exercise reserve for years. Others have a transition to HF that may be due to diastolic dysfunction, or systolic dysfunction, or both.38 The ECG remains a clinical tool, quickly and easily available to most practitioners, at a relatively small cost.84 ECG criteria have a high specificity (ability to

431

432

CHAPTER 15  Heart Failure Normal heart

Right ventricle

Left ventricular hypertrophy

Left ventricle

Thickening of the myocardium of the left ventricle

FIGURE 15-33  LVH is a thickening of the myocardium of the LV.

TABLE 15-28 Causes of LVH and Its Treatment Cause

Nonpharmacologic Treatment

Pharmacologic Treatment

Aortic regurgitation

Surgical correction

Calcium-channel blockers ACE inhibitors

AS

SAVR TAVR

Supportive therapy

Congenital heart disease

Surgical correction

Supportive therapy

Hypertension

Weight reduction Exercise Sodium restriction Alcohol reduction Smoking cessation

Diuretics Beta-blockers Alpha2 adrenergic agonists Alpha1 antagonists Calcium-channel blockers Angiotensin II receptor blockers Direct renin inhibitor

HCM

Genetic counseling Myomectomy Percutaneous septal ablation

Beta-blockers Calcium-channel blockers Type IA antiarrhythmic agents

MR

Acute MR before surgery intra-aortic balloon pump Mitral valve repair Mitral valve replacement

Acute MR—intravenous nitroprusside, nitroglycerin

Obesity

Weight reduction

Supportive therapy

rule in LVH) but low sensitivity (unable to always rule out LVH).85 TEE has poor reproducibility and is costly. CMRI is currently the gold standard for assessing LV mass. It is highly specific and highly sensitive, and has excellent reproducibility.85 However, it is costly and not

readily available. So, the 12-lead ECG remains the simple and cost-effective screening test for LVH. The treatment, risk factors, and prognosis for LVH depend on its cause. See Table 15-28 for causes of LVH and a summary of its treatments.

Key Points

KNOWLEDGE CHECK QUESTIONS 1. True or False: Hypertension causes chronic pressure overload in the LV. 2. True or False: Aortic regurgitation causes chronic volume overload in the LV.

Chapter Summary HF is the heart’s inability to supply the blood needed by the body to survive. It can be caused due to a filling problem, or pumping problem, or both, and becomes progressively worse unless treated. HF is not a disease itself, but a complication of other diseases. As a result, HF and its underlying cause must be treated. Two scales quantify HF (NYHA functional class and the American Heart Association and American College of Cardiology Foundation [AHA/ACCF]). HF can result from one or more of the following: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14.

CHD MI Hypertension Heart valve failure Heart damage (due to alcohol, drug abuse, or chemotherapy) Cardiomyopathy (dilated, hypertrophic, or restrictive) Congenital heart disease Pulmonary emboli Myocarditis (bacterial or viral) HIV VSD ASD Diabetes Pericardial disease

Currently, more than 5.8 million people in America and more than 23 million worldwide are diagnosed with HF. Each year more than 550,000 new cases are diagnosed, and in 2009, 1 in 9 deaths included HF as the contributing cause. By the year 2030, the prevalence of HF will increase 25% from the 2013 estimates. The total medical cost for HF in 2012 was $20.9 billion, and is expected to increase to $53.1 billion by 2030; this is a 2.5-fold increase. HF among the different racial and ethnic groups is expected to increase substantially. The African American population will have the largest increase followed by white non-Hispanic; white Hispanics will have the lowest increase. HF can be either left or right sided. It can be acute or chronic. It can occur during diastole or systole. Left-sided HF or pulmonary disease causes rightsided HF. The problem can be a forward, backward, or congestive failure. The diseases that can cause HF

are the cardiomyopathies (dilated, hypertrophic, obstructive, or restrictive), ventricle hypertrophy, heart valve problems, defects in the ventricle or atrial septal wall, or pericarditis. The causes of the diseases can be congenital, CAD, infections, trauma, cancer, or gene mutations. The tests that can be performed to diagnose HF are CXR, blood test, echocardiogram, Doppler echocardiogram, ECG, heart catheterization, treadmill exercise stress test, and/or tracer study. The treatment for HF includes medication, valve repair or replacement, surgery to repair a defect in the septal wall, putting a pericardial window, removing the pericardium, or heart transplant. Risk factors can be family history, gender, age, diet, smoking, or alcohol. Complications can be death, stroke, heart attack, valve problem, or infections. Prognosis can be good with early intervention to poor.

Key Points 1. HF occurs when cardiac output cannot meet the body’s metabolic demands. 2. There are two types of chronic HF: (1) HF with REF due to impaired LV systolic function and (2) HF with PEF due to diastolic dysfunction. 3. HF can occur on the right side, or the left side, or both sides. 4. Symptoms of HF may be brought on by increased metabolic demand, increase circulating volume, increased afterload, or decreased contractility. 5. HF treatment requires the identification, elimination, or treatment of the underlying condition causing the HF. 6. Medications for HF with REF include ACE inhibitors, beta-blockers, and, if necessary, diuretics, and inotropic drugs or ARB for those who do not tolerate ACE inhibitors. Medications for HF with PEF include diuretics and vasodilators. 7. The cardiomyopathies are heart muscle diseases that are classified by their pathophysiology as dilated, hypertrophic, or RCMs. 8. LV dilation with impaired systolic function is the hallmark of dilated cardiomyopathies. Thickening of the LV with impaired diastolic relaxation is the pathology behind hypertrophic cardiomyopathies. Ventricular arrhythmias associated with HCM cause sudden death. The rarest of the cardiomyopathies is RCM, characterized by an impairment of diastolic ventricular relaxation. All cardiomyopathies cause HF symptoms. 9. Rheumatic fever and congenital issues are the causes of a number of valvular heart diseases. Treatment of these valve diseases depends on the severity of the valve lesions and symptoms. Treatment ranges from no treatment to open-heart surgery for valve replacement.

433

434

CHAPTER 15  Heart Failure 10. Ventricular and ASDs are congenital heart defects that are present at birth. Mild defects may remain asymptomatic until adulthood. The larger the defect, the more likely it will be detected in infancy. Septal defects allow blood to be shunted between atria or ventricles, bypassing the blood’s normal course. Symptomatic septal defects are treated with surgical or percutaneous repair. 11. Acute pericarditis usually has an idiopathic or viral etiology. Common findings include chest pain and fever. Complications of acute pericarditis include pericardial effusions, constrictive pericarditis, and cardiac tamponade. Excessive fluid in the pericardial sac is drained by pericardiocentesis. 12. LVH is a consequence of LV compensation for chronic pressure or chronic volume overload due to a variety of etiologies. ECG remains the quickest, easiest, and least expensive method of detection for LVH. Treatment depends on the etiology.

Chapter Questions 1. Heart failure (HF) occurs when ________________. a. the heart is unable to meet the body’s metabolic needs b. the heart stops working c. the heart has a congenital problem d. the left ventricle (LV) becomes hypertrophied 2. In 2009, what was the mortality rate for HF? a. 1 in 15 b. 1 in 20 c. 1 in 9 d. 1 in 5 3. HF can affect ________________________. a. only the left side of the heart b. only the right side of the heart c. both sides of the heart d. the cardiac valves only 4. Tests used to diagnose HF include which of the following? a. Heart catheterization b. Electrocardiogram c. Blood test d. All of the above 5. Besides the initial cause of the HF, what else must be treated? a. Peripheral vascular problem b. Neuroendocrine system c. Muscular system d. Central nervous system 6. When the right heart is affected, which other ­system become congested? a. Pulmonary system b. Arterial system c. Venous system d. All of the above

 7. The total direct medical cost for HF in 2012 was _____________. a. $8 billion b. $20.9 million c. $579 million d. $20.9 billion  8. Left HF is when the systolic and/or the diastolic function is compromised, resulting in ____________________. a. increased LV end-systolic pressure b. increased LV end-diastolic pressure c. decreased LV end-systolic pressure d. decreased LV end-systolic pressure  9. What is the most common cause of right-sided HF? a. Cardiac arrhythmias b. Renal failure c. Left-sided HF d. Venous insufficiency 10. Right-sided HF will cause which of the following? a. Chest pain b. Liver enlargement c. Stroke d. Pulmonary edema 11. What medication below can be a treatment for HF? a. ACE inhibitors b. Vasodilators c. Beta-blockers d. All of the above 12. Of the etiologies listed below, which one does NOT cause idiopathic dilated cardiomyopathy? a. Toxins b. Alcohol c. Virus d. Inherited 13. What are the estimated drinks per day needed to develop alcoholic DCM? a. 2 b. 4 c. 10 d. 8 14. What is the usual cause of hypertrophic cardiomyopathy (HCM)? a. Hypertension b. Aortic stenosis c. Inherited d. None of the above 15. The obstruction in HCM occurs in which area? a. Supravalvular b. Subvalvular c. At the valve d. Within the ventricle

References 16. Symptoms that are seen in acute aortic insufficiency are the same as ___________. a. HCM b. restrictive cardiomyopathy (RCM) c. constrictive pericarditis d. DCM 17. The heart sound heard with aortic stenosis is a ________________. a. loud systolic murmur b. diastolic murmur c. loud S2 sound d. low S1 sound 18. Mitral regurgitation is caused by which of the following? a. Syphilis b. Infectious endocarditis c. Renal failure d. Hypertension 19. Which arrhythmia is common with mitral stenosis? a. Sinus tachycardia b. Sinus bradycardia c. Atrial fibrillation d. Atrial tachycardia 20. Acute pericarditis can lead to _____________________. a. cardiac tamponade b. HCM c. RCM d. DCM

References 1. What Is Heart Failure? National Lung, Heart, and Blood Institute. http://www.nhlbi.nih.gov/health/health-topics/topics /hf. Accessed July 10, 2015. 2. Right-Sided Heart Failure. eMedicineHealth. http://www .emedicinehealth.com/right-sided_heart_failure-health/article _em.htm. Accessed July 10, 2015. 3. Heart Failure Fact Sheet. Centers for Disease Control and Prevention. http://www.cdc.gov/dhdsp/data_statistics/fact_sheets/fs _heart_failure.htm. Accessed July 10, 2015. 4. What Causes Heart Failure? National Lung, Heart, and Blood Institute. http://www.nhlbi.nih.gov/health/health-topics/topics /hf/causes. Accessed July 10, 2015. 5. Heart Failure. Mayo Clinic. http://www.mayoclinic.org/diseases -conditions/heart-failure/basics/causes/con-20029801. Accessed July 13, 2015. 6. McMurray JJ, Adamopoulos S, Anker SD, et al. ESC guidelines for the diagnosis and treatment of acute and chronic heart failure 2012. Eur Heart J. 2012;33:1787–1847. doi:10.1093/eurheart/ehs104. 7. Stages of Heart Failure. Heartfailure.org. http://www.heartfailure .org/heart-failure/the-stages-of-heart-failure. Accessed July 14, 2015. 8. Roger V. Heart failure compendium: epidemiology of heart failure. Circ Res. 2013;113:646–659. doi:10.1161/CIRCRESAHA.113.300268. 9. Go A, Mozaffarian D, Roger V, et al. AHA statistical update: heart disease and stroke statistics—2013 update. Circulation. 2013;127: e6–e245. doi:10.1161/CIR.0b013e31828124ad. 10. Heidenreich PA, Albert NM, Allen LA, et al. Forecasting the impact of heart failure in the United States a policy statement from the American Heart Association. Circ Heart Fail. 2013;6(3):606–619.

11. Beyond the Basics: Right vs. Left Heart Failure. EMS World. http:// www.emsworld.com/article/10323146/beyond-the-basics-right-vs -left-heart-failure. Accessed July 14, 2015. 12. Heart Failure. University of Maryland Medical Center. http:// umm.edu/health/medical/reports/articles/heart-failure. Accessed July 14, 2015. 13. Kirk J, Diercks D, Dhingr K. Acute heart failure. In: Aghababian R, ed. Essentials of Emergency Medicine. 2nd ed. Sudbury, CA: Jones & Bartlett Learning; 2011:122–129. 14. Lee C, Dec G, Lilly L. The cardiomyopathies. In: Lilly L, ed. Pathophysiology of Heart Disease. 5th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2011:244–260. 15. Heart Disease and Dilated Cardiomyopathy. WebMD. http:// www.webmd.com/heart-disease/guide/dilated-cardiomyopathy. Accessed July 23, 2015. 16. Alcoholic Cardiomyopathy. Health Central. http://www.health central.com/encyclopedia/adam/alcoholic-cardiomyopathy-4006997 /symptoms. Accessed July 23, 2015. 17. Arnold JMO. Dilated Cardiomyopathy. Merck Manuals Professional Edition. http://www.merckmanuals.com/professional/cardiovascular -disorders/cardiomyopathies/dilated-cardiomyopathy. Accessed August 3, 2015. 18. Who Is at Risk for Cardiomyopathy? National Heart, Lung, and Blood Institute. http://www.nhlbi.nih.gov/health/health-topics /topics/cm/atrisk. Accessed August 8, 2015. 19. Mayo Clinic Staff. Dilated Cardiomyopathy. Mayo Clinic. https:// www.mayoclinic.org/diseases-conditions/dilated-cardiomyopathy /symptoms-causes/syc-20353149. Accessed August 9, 2015. 20. Goswami VJ. Dilated Cardiomyopathy. Medscape. http://emedicine .medscape.com/article/152696-overview#a7. Accessed August 10, 2015. 21. Piano MR. Alcoholic cardiomyopathy incidence, clinical characteristics, and pathophysiology. Chest. 2002;121:1638–1650. doi:10.1378/chest.121.5.1638. 22. Hazebroek M, Dennert R, Heymans S. Idiopathic dilated cardiomyopathy: possible triggers and treatment strategies. Neth Heart J. 2012;20(7–8):332–335. doi:10.1007/s12471-012-0285-7. 23. Pantazis A, Vischer AS, Perez-Tome MC, Castelletti S. Diagnosis and management of hypertrophic cardiomyopathy. Echo Research and Practice. 2015;2(1):R45-R53. doi:10.1530/ERP-15-0007. 24. Hypertrophic Cardiomyopathy. American Heart Association. http:// www.heart.org/HEARTORG/Conditions/More/Cardiomyopathy /Hypertrophic-Cardiomyopathy_UCM_444317_Article.jsp. Accessed July 20, 2015. 25. Hypertrophic Cardiomyopathy. Cleveland Clinic. http://my .clevelandclinic.org/services/heart/disorders/hcm. Accessed July 21, 2015. 26. Hypertrophic Cardiomyopathy—Adult. Mount Sinai Hospital. https://www.mountsinai.org/patient-care/health-library/diseases -and-conditions/hypertrophic-cardiomyopathy-adult. Accessed July 21, 2015. 27. Mayo Clinic Staff. Hypertrophic Cardiomyopathy. Mayo Clinic. http://www.mayoclinic.org/diseases-conditions/hypertrophic -cardiomyopathy/symptoms-causes/dxc-20122103. Accessed August 9, 2015. 28. Arnold MO. Hypertrophic Cardiomyopathy. Merck Manual Professional Edition. http://www.merckmanuals.com/professional /cardiovascular-disorders/cardiomyopathies/hypertrophic -cardiomyopathy. Accessed August 10, 2015. 29. Wang SS, Lange RA. Aortic Regurgitation. Medscape. http:// emedicine.medscape.com/article/150490-overview. Accessed July 15, 2015. 30. Arnold JM. Restrictive Cardiomyopathy. Merck Manual Professional Edition. http://www.merckmanuals.com/professional/cardiovascular -disorders/cardiomyopathies/restrictive-cardiomyopathy. Accessed July 21, 2015.

435

436

CHAPTER 15  Heart Failure 31. Moore K. Restrictive Cardiomyopathy. Healthline. http://www .healthline.com/health/restrictive-cardiomyopathy#Overview1. Accessed August 9, 2015. 32. Wang SS. Aortic Regurgitation Workup. Medscape. http:// emedicine.medscape.com/article/150490-workup#showall. Accessed August 3, 2015. 33. Armstrong GP. Aortic Regurgitation. Merck Manual Professional Edition. http://www.merckmanuals.com/professional /cardiovascular-disorders/valvular-disorders/aortic-regurgitation. Accessed August 7, 2015. 34. Aortic Valve Insufficiency: Causes, Symptoms & Diagnosis. Healthline. https://www.healthline.com/health/aortic-insufficiency. 2018. Accessed September 24, 2018. 35. Chen M. Aortic Insufficiency. MedlinePlus. http://www.nlm.nih .gov/medlineplus/ency/article/000179.htm. Accessed August 9, 2015. 36. Ren X. Pulmonic Regurgitation Workup. Medscape. http:// emedicine.medscape.com/article/157639-workup#showall. Accessed August 4, 2015. 37. Aortic Regurgitation - Doctors Lounge (TM). 2017. https://www .doctorslounge.com/cardiology/diseases/aortic_incompetence.htm 38. Lorell BH, Carabello BA. Left ventricular hypertrophy: pathogenesis, detection, and prognosis. Circulation. 2000;102(4):470–479. doi:10.1161/01.CIR.102.4.470. 39. Armstrong GP. Aortic Stenosis. Merck Manuals Professional Edition. http://www.merckmanuals.com/professional/cardiovascular -disorders/valvular-disorders/aortic-stenosis. Accessed August 10, 2015. 40. Heart Valve Disease—Percutaneous Interventions. Cleveland Clinic. http://my.clevelandclinic.org/services/heart/disorders/valve treatment/percutaneousValve. Accessed August 8, 2015. 41. Mayo Clinic Staff. Aortic Valve Stenosis. Mayo Clinic. http://www .mayoclinic.org/diseases-conditions/aortic-stenosis/basics /risk-factors/con-20026329. Accessed August 9, 2015. 42. Problem: Heart Valve Stenosis. 2018 http://www.heart.org/en/health -topics/heart-valve-problems-and-disease/heart-valve-problems-and -causes/problem-heart-valve-stenosis. Accessed July 15, 2015. 43. Understanding Rheumatic Fever—the Basics. WebMD. http://www .webmd.com/a-to-z-guides/understanding-rheumatic-fever-basics. Accessed July 20, 2015. 44. Endocarditis, Infective. WebMD. http://www.webmd.com/heart -disease/endocarditis-infective. Accessed July 20, 2015. 45. Armstrong GP. Mitral Valve Prolapse (MVP). Merck Manual Professional Edition. http://www.merckmanuals.com/professional /cardiovascular-disorders/valvular-disorders/mitral-valve-prolapse -mvp. Accessed July 20, 2015. 46. Burton LV, Beier K. Papillary Muscle Rupture. [Updated 2018 May 11]. Treasure Island, FL: StatPearls Publishing; 2018 https:// www.ncbi.nlm.nih.gov/books/NBK499976/. Accessed September 24, 2018 47. Armstrong GP. Mitral Regurgitation. Merck Manual Professional Edition. http://www.merckmanuals.com/professional /cardiovascular-disorders/valvular-disorders/mitral-regurgitation. Accessed July 27, 2015. 48. Garcia GB, Holtz EH. 12-Lead ECG: The Art of Interpretation. Burlington, MA: Jones & Bartlett Learning; 2013. 49. Sundstrom J, Lind L, Arnlov J, Zethelius B, Andren B, Lithell H. Echocardiographic and electrocardiographic diagnoses of left ventricular hypertrophy predict mortality independently of each other in a population of elderly men. Circulation. 2001;103(19):2346–2351. doi:10.1161/01.cir.103.19.2346. 50. Mayo Clinic Staff. Mitral Valve Stenosis. Mayo Clinic. https://www .mayoclinic.org/diseases-conditions/index?letter=M. Accessed August 9, 2015. 51. Armstrong GP. Mitral Stenosis. Merck Manual Professional Edition. http://www.merckmanuals.com/professional/cardiovascular -disorders/valvular-disorders/mitral-stenosis. Accessed August 10, 2015.

52. Ren X, Lange RA. Pulmonic Regurgitation: Background. Medscape. http://emedicine.medscape.com/article/157639-overview. Accessed July 15, 2015. 53. Ren X, Lange RA. Pulmonic Regurgitation: Clinical Presentation History. Medscape. http://emedicine.medscape.com/article/157639 -clinical#b1. Accessed July 27, 2015. 54. Ren X, Lange RA. Pulmonic Regurgitation: Clinical Presentation Physical. Medscape. http://emedicine.medscape.com/article/157639 -clinical#b4. Accessed July 27, 2015. 55. Pulmonary Regurgitation. Epocrates. https://online.epocrates .com/u/2932474/Pulmonary+regurgitation. Accessed August 8, 2015. 56. Ren X, Lange RA. Pulmonic Regurgitation: Follow-Up. Medscape. http://emedicine.medscape.com/article/157639-followup#e7. Accessed August 10, 2015. 57. Armstrong GP. Pulmonic Stenosis. Merck Manual Professional Edition. http://www.merckmanuals.com/professional/cardiova scular-disorders/valvular-disorders/pulmonic-stenosis. Accessed August 15, 2015. 58. Rao PS. Valvar Pulmonary Stenosis. Medscape. http://emedicine .medscape.com/article/891729-overview#a5. Accessed August 15, 2015. 59. Mayo Clinic Staff. Pulmonary Valve Stenosis: Risk Factors. Mayo Clinic. http://www.mayoclinic.org/diseases-conditions/pulmonary -valve-stenosis/basics/risk-factors/con-20013659. Accessed ­August 15, 2015. 60. Mayo Clinic Staff. Pulmonary Valve Stenosis: Complications. Mayo Clinic. http://www.mayoclinic.org/diseases-conditions /pulmonary-valve-stenosis/basics/complications/con-20013659. Accessed August 15, 2015. 61. Armstrong GP. Tricuspid Regurgitation. Merck Manual Professional Edition. http://www.merckmanuals.com/professional/cardiovascular -disorders/valvular-disorders/tricuspid-regurgitation. Accessed July 22, 2015. 62. Bruce C, Connolly H. Right-sided valve disease deserves a little more respect. Circulation. 2009;119(20):2726–2734. doi:10.1161 /circulationaha.108.776021. 63. Nall R. Tricuspid Regurgitation (Tricuspid Valve Insufficiency). HealthLine. http://www.healthline.com/health/tricuspid -regurgitation#Overview1. Accessed August 10, 2015. 64. Armstrong GP. Tricuspid Stenosis. Merck Manual Professional Edition. http://www.merckmanuals.com/professional/cardio vascular-disorders/valvular-disorders/tricuspid-stenosis. Accessed July 22, 2015. 65. Mancini M. Tricuspid Regurgitation Clinical Presentation. Medscape. http://emedicine.medscape.com/article/158484-clinical#b1. Accessed August 9, 2015. 66. HVD-Tricuspid Valve Disease. The International Heart Institute Foundation. http://www.ihimontanafoundation.org/Heart _Information/Heart_Conditions/HVDTricuspid_Valve_Disease. Accessed August 10, 2015. 67. Adler DH. Atrial Septal Defect Treatment and Management. Medscape. http://emedicine.medscape.com/article/162914-treatment#d14. Accessed August 10, 2015. 68. Berg DD, Brown DW. Congenital heart disease. In: Lilly L, ed. Pathophysiology of Heart Disease. 5th ed. Philadelphia, PA: ­Lippincott Williams & Wilkins; 2011:361–385. 69. Sommer R, Hijazi Z, Rhodes J. Pathophysiology of congenital heart disease in the adult: part I: shunt lesions. Circulation. 2008;117(8):1090–1099. doi:10.1161/circulationaha.107 .714402. 70. Ramaswamy P. Ventricular Septal Defects Clinical Presentation. Medscape. http://emedicine.medscape.com/article/892980-clinical. Accessed August 3, 2015. 71. Merlin M. Ventricular Septal Defect. Emedicinehealth. http://www .emedicinehealth.com/ventricular_septal_defect/page5_em.htm. Accessed August 6, 2015.

References 72. Mersch J. Ventricular Septal Defect. MedicineNet. http://www .medicinenet.com/ventricular_septal_defect/page3.htm#how_is_a _small_vsd_treated. Accessed August 8, 2015. 73. Pediatric Cardiothoracic Surgery–Ventricular Septal Defect. 2018. https://pediatricct.surgery.ucsf.edu/conditions--procedures /ventricular-septal-defect.aspx. Accessed September 24, 2018. 74. Krause L. What Is Ventral Septal Defect (VSD)? Healthline. http:// www.healthline.com/health/ventricular-septal-defect#Overview1. Accessed August 9, 2015. 75. Ramaswamy P. Discrete Fibrous Subaortic Stenosis. Medscape. http://emedicine.medscape.com/article/892980-clinical#showall. Accessed August 10, 2015. 76. Adler DH. Atrial Septal Defect Workup. Medscape. http:// emedicine.medscape.com/article/162914-workup#showall. Accessed August 7, 2015. 77. Mayo Clinic Staff. Atrial Septal Defect (ASD). Mayo Clinic. http:// www.mayoclinic.org/diseases-conditions/atrial-septal-defect/basics /risk-factors/con-20027034. Accessed August 9, 2015. 78. Types of Holes in the Heart: Atrial Septal Defect. The University of California, San Francisco: Department of Surgery. http://www .surgery.ucsf.edu/conditions--procedures/ventricular-septal-defect .aspx. Accessed August 10, 2015. 79. Hoit BD. Pericarditis. Merck Manual Professional Edition. http:// www.merckmanuals.com/professional/cardiovascular-disorders /pericarditis/pericarditis#v939902. Accessed July 21, 2015.

80. Ren Y, Lilly LS. Diseases of the pericardium. In: Lilly L, ed. Pathophysiology of Heart Disease. 5th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2011:324–338. 81. Chandraratna P, Mohar D, Sidarous P. Role of echocardiography in the treatment of cardiac tamponade. Echocardiography. 2014;31(7):899–910. doi:10.1111/echo.12605. 82. Degirmencioglu A, Karakus G, Güvenc T, Pinhan O, Sipahi I, Akyol A. Echocardiography-guided or “sided” pericardiocentesis. Echocardiography. 2013;30(9):997–1000. doi:10.1111/echo .12214. 83. Drazner MH. Contemporary reviews in cardiovascular medicine: the progression of hypertensive heart disease. Circulation. 2011;123:327–334. doi:10.1161/circulationaha.108.845792. 84. Estes E, Jackson K. The electrocardiogram in left ventricular hypertrophy: past and future. J Electrocardiol. 2009;42(6):589–592. doi:10.1016/j.jelectrocard.2009.06.016. 85. Klodas E. High Blood Pressure and Hypertensive Heart Disease. WebMD. http://www.webmd.com/hypertension-high-blood -pressure/guide/hypertensive-heart-disease?page=2#2. Accessed August 7, 2015.

437

CHAPTER

16 © TairA/Shutterstock

Ischemic Heart Disease

“When the heart speaks, the mind finds it indecent to object.” —Milan Kundera, 1984

OUTLINE Introduction Definition and Diagnosis Etiology Epidemiology Pathology/Pathophysiology Clinical Manifestations Noninvasive Diagnostic Testing Twelve Lead Electrocardiogram Exercise Stress Testing Pharmacologic (Chemical) Stress Test Echocardiogram Radiological Imaging Computed Tomography Diagnostic Testing—Invasive Coronary Angiograms Fractional Flow Reserve IntraVascular UltraSound/Optical Coherence Tomography Treatment and Management Angioplasty Plain Old Balloon Angioplasty Rotational Atherectomy Stents Coronary Artery Bypass Grafting Cardiac Rehabilitation Risk Factors Prevention Complications Prognosis

OBJECTIVES 1. State the working definition of ischemic heart disease (IHD). 2. Outline the incidence, prevalence, and risk factors for IHD. 3. Define and discuss secondary problems associated with IHD. 4. Predict the clinical manifestations of a patient with IHD. 5. Explain diagnostic testing used in identifying IHD. 6. Summarize the recommended management of patients with IHD. 7. Identify common complications associated with IHD. 8. Discuss the prognosis of IHD.

KEY TERMS Aerobic metabolism Anaerobic metabolism Angina pectoris Atherosclerosis Bare-metal stent (BMS) Bruce protocol Carotid bruit Coronary artery bypass grafting (CABG) Coronary artery disease (CAD) Coronary heart disease Drug-eluting stent (DES)

Dual antiplatelet therapy (DAPT) Fatty streak Fractional flow reserve (FFR) Heart disease Heart failure High-density lipoprotein (HDL) Hyperacute phase Hyperemia Indeflator Intima

439

440

CHAPTER 16  Ischemic Heart Disease Ischemia Ischemic heart disease (IHD) Intravascular ultrasound (IVUS) Left heart catheterization Low-density lipoprotein (LDL)

Optical coherence tomography (OCT) Pathologic Q wave Percutaneous coronary angioplasty Prinzmetal angina Restenosis Resting scan

Rotational atherectomy Silent heart attack Spontaneous coronary artery dissection (SCAD) Stable angina

Stent Stress scan Translesional pressure Unstable angina Variant angina

Case Study A 58-year-old female attorney has her first appointment with a new family physician. She has been experiencing some unusual symptoms lately. Her symptoms are discomfort in both arms, breaking out in a cold sweat, pain in her jaw, nausea, and shortness of breath without chest discomfort. Originally, these symptoms appeared only when she was having an extremely stressful day at work; however, lately the symptoms have been appearing even when she is resting. Before going to see her family physician, she tried using antacids to help with nausea and acetaminophen to help with the pain, but this did not help. When she told her current family physician about them, he just told her it was anxiety and stress and gave her an anti-anxiety medication. The medication did not seem to help, so she decided to see a new physician and hopes the new physician can diagnose her problem. In addition to her job, she has a husband that travels a lot for his job, and she cares for two young children at home. She does not smoke, but she is

Introduction Ischemic heart disease (IHD) is coronary heart disease (CHD) or coronary artery disease (CAD).1 IHD can lead

to a heart attack and ischemic cardiomyopathy.1,2 Statistics from the Centers for Disease Control and Prevention (CDC) shows that IHD is the number one killer of men and women in the United States, and approximately 611,000 died in 2009 from heart disease.3 While genetics has a large influence on CAD, there are other risk factors that are independent of genetics. Table 16-1 lists the uncontrollable and controllable risk factors for IHD. The American Heart Association (AHA) reports that the annual cost of treating IHD is over $108 billion.3 As the population in America ages, the cost of heart disease increase. One study puts the cost at $818 billion by the year 2030.5 In an effort to reduce risk and cost, the AHA and the American College of Cardiology

around secondhand smoke all day. She denies illicit drug use or alcohol abuse. She admits to not exercising on a regular basis, citing her work and home schedule is too busy to find the time. Her mother and father are still alive, and both receive treatment for heart disease. On physical examination, the patient was not experiencing any pain, discomfort, nausea, or shortness of breath. The exam reveals hypertension with a blood pressure of 154/102 mm Hg. The patient’s temperature is 97.9°F, respiratory rate is 16 breaths/minute, and pulse is 102 beats/minute. She is 65 inches tall, weighs 162 pounds, and has a body mass index (BMI) of 27. She has no heart murmurs, no carotid bruit (a sound caused by turbulent blood flow in the carotid artery resulting from stenosis of the artery). The patient’s lungs are clear to auscultation. An electrocardiogram (ECG) performed in the office revealed sinus tachycardia with ST-segment changes in leads V1 through V4, indicating anteroseptal ischemia.

TABLE 16-1 Uncontrollable and Controllable IHD Risk Factors Uncontrollable IHD Risk Factors

Controllable IHD Risk Factors

Age Gender Family history History of preeclampsia during pregnancy

Hypertension Hyperlipidemia Diabetes and prediabetes Tobacco smoking Overweight or obese Physically inactivity Unhealthy diet4

Foundation (ACCF) released their updated 2011 guideline for prevention and risk reduction therapy for CHD.6 This guideline lists several strategies and goals that need to be implemented (Table 16-2).

Etiology

TABLE 16-2 AHA/ACCF Goals for Prevention and Risk Reduction for CHD Risks

Goals/Strategies

Smoking

Complete cessation

Hypertension

Below 140/90 mm Hg; if diabetic, kidney failure, or CAD then below 130/80 mm Hg

Hyperlipidemia

LDL-C below 100 mg/dL

Physical inactivity

A least 30 minutes of physical activity every day (5 days minimum)

Obesity

BMI: 18.5–24.9 kg/m

Diabetes

Control blood sugar and A1c

Blood clots

75–162 mg aspirin daily (unless contraindicated)

KNOWLEDGE CHECK QUESTIONS 1. True or false: A history of preeclampsia during pregnancy is a controllable risk factor for IHD. 2. True or false: Another name for IHD is CAD.

Definition and Diagnosis Diet and exercise can prevent, delay, or reverse CHD. The cause of CHD is plaque buildup in the coronary arteries, known as atherosclerosis (Figure 16-1).7 As the plaque builds in the coronary arteries, the lumen of the vessels become narrowed, reducing the amount of blood the heart receives. When this happens, the heart does not receive the oxygen supply it needs to function properly; this is ischemia.8 Ischemia can manifest itself in different ways. The most obvious one is severe chest pain; however, shortness of breath and sweating (diaphoretic) are common. Other signs, which may not always be visible, are chest pressure or discomfort, indigestion, weakness, nausea, dizziness, and rapid heartbeat. These symptoms may appear only while the person is under exertion, known as stable angina, or they can appear at rest, known as unstable angina.9 Both men and women may experience these symptoms. Also, women may experience neck, jaw, shoulder, upper back or abdominal discomfort, right arm pain, unusual fatigue, or no pain at all (known as a silent heart attack).10

Normal artery

Atherosclerosis and blood clot

FIGURE 16-1  Normal artery and artery with atherosclerosis.

KNOWLEDGE CHECK QUESTIONS 1. True or false: The buildup of plaque in the coronary arteries is called atherosclerosis. 2. True or false: Chest pain that subsides with rest following exertion is unstable angina.

Etiology The main cause of IHD is atherosclerosis.11 The atherosclerosis process starts when the intima layer (inner layer) of the artery becomes damaged. Figure 16-2 shows the proper anatomy of an artery. Damage to the intima layer occurs from high blood pressure, smoking, high levels of certain fats and cholesterol, and diabetes.12 Other causes of IHD are coronary artery spasms and dissections.13

KNOWLEDGE CHECK QUESTIONS 1. True or false: Damage to the intima layer of the artery begins the atherosclerosis process. 2. True or false: Smoking does not damage the intima layer of the coronary arteries.

441

442

CHAPTER 16  Ischemic Heart Disease

FIGURE 16-2  Anatomy of an artery. © Tefi/Shutterstock.

Epidemiology The diseases/conditions that included in the term cardiovascular disease (CVD) are IHD, stroke, arrhythmias, heart valve disorders, and peripheral vascular disease (PVD).14 Of the 611,000 people that died in 2010 of CVD, approximately 370,000 died from IHD.3 The breakdown of the demographics for 2010 appears in Table 16-3. Every year approximately 735,000 people have a heart attack. The majority, 525,000, represent people who are having their first heart attack. The remaining 210,000 represents people who have had previous heart attacks.15 The prevalence of CVD in the United States shows that over 82 million people have one form of CVD, approximately 16 million with IHD. Almost 8 million people have heart attacks each year, 9 million with angina pectoris.16 The death rate from CVD is higher than that from any other disease in the world. According to the World Health Organization, of the 17.5 million deaths

TABLE 16-3 2010 CVD Mortality Demographics Group

Rate

Males

210,000

Females

176,000

White, non-Hispanic

315,000

Black, non-Hispanic

39,000

Hispanic

20,000

Asian/Pacific Islander

7,600

American Indian/Alaska Native

1,700

Heart Disease Fact Sheet: Centers for Disease Control and Prevention. http://www.cdc.gov/dhdsp/data_statistics/fact_sheets/fs_heart _disease.htm. Published February 19, 2015. Accessed June 26, 2015.

in 2012, 6.7 million died from IHD. Heart disease represented 31% of all global deaths.17 The total cost for CVD in 2012 was over $300 billion. The direct costs (hospital, home health, and prescriptions) for CVD in 2012 were over $195 billion, and the indirect costs (lost productivity/mortality) were over $124 billion.18 The AHA 2030 projection for CVD in the United States is over 43%.18

KNOWLEDGE CHECK QUESTIONS 1. True or false: CVD is the number one killer in the world. 2. True or false: CVD does not include PVD.

Pathology/Pathophysiology CAD is the result of plaque building up in the coronary arteries, a process known as atherosclerosis. When this occurs, the blood supply to the heart is diminished, and the heart muscle becomes ischemic, which may cause a heart attack.11 The atherosclerotic process does not happen all at once but is a chronic condition.19 Damage to the intimal layer of the coronary artery is the first step in the process.12 Figure 16-3 demonstrates the development of atherosclerosis. The human body needs cholesterol to function, and there are two types of cholesterol. One is the low-density lipoprotein (LDL), which is the bad cholesterol, and the other is the high-density lipoprotein (HDL), which is the good cholesterol.11 Damage to the intima causes LDL to migrate from the blood into the subendothelial space between the intima and media. Upon reaching the subendothelial space, the LDL oxidizes. As a result, the modified LDLs become potent chemotactic molecules that promote monocyte adhesion and migration to the subendothelial space.19 Monocytes become macrophages in the subendothelial space and phagocytize (ingest) the modified LDL, and become foam cells. These cells have

Pathology/Pathophysiology

Endothelial dysfunction

Fatty streak formation

Stable (fibrous plaque formation

Plaque rupture thrombosis Atherosclerosis and blood clot FIGURE 16-3  The development of atherosclerosis.

proinflammatory functions and release cytokines, such as interleukins and tumor necrosis factor. This process forms a fatty streak in the subendothelial space.19 After the formation of the fatty streak, lymphocytes and mast cells accumulate in the subendothelial space. The migration of these cells results in cellular and humoral immune responses, which causes a chronic inflammatory state in the artery producing several proinflammatory molecules.19 The next step in the atherosclerotic process is the migration of smooth muscle cells (SMC) from the medial layer of the artery into the intima. This transforms the fatty streak to a more complex lesion.19 The migration of the SMCs into the subendothelial space produces extracellular matrix molecules. These extracellular matrix molecules create the fibrous cap that covers the fatty streak.19 After the fibrous cap is formed, the foam cells inside start to die, resulting in the release of lipids. These lipids accumulate in the

extracellular space, forming a lipid-rich pool known as the necrotic core.19 At this point in the atherosclerotic process, the plaque becomes either stable or unstable (unstable plaque is also called vulnerable plaque).19 The key ingredient that determines this is the thickness of the fibrous cap. The cap on a stable plaque is intact, thick, and composed of SMCs in a matrix rich in Type I and III collagen. As this kind of plaque grows and protrudes into the lumen of the artery, it reduces the quantity of blood reaching the heart muscle. This lesion will usually produce angina only upon exertion, which is called stable angina.19 The cap on the unstable plaque is thin and consists mainly of Type I collagen, and has few or no SMCs. However, there are abundant macrophage, proinflammatory, and prothrombotic molecules.19 Unstable plaques are more vulnerable to erosion or rupture. If the plaque ruptures, the core is exposed to

443

444

CHAPTER 16  Ischemic Heart Disease circulating coagulation proteins, which can cause a clot to form (thrombosis). When the clot forms, it results in the coronary artery occlusion, which leads to acute coronary syndrome (ACS), also known as an acute myocardial infarction (AMI).19 Prinzmetal angina or variant angina is another type of CAD that is caused by coronary spasms.20 This rare condition accounts for only 2 out of every 100 angina cases. The stimuli for this type of angina are thought to be exertion or stress. It occurs while the person is at rest, and between the hours of midnight and morning.20 Some of the factors that can cause coronary spasms are cold weather, cocaine, stress, medications, or smoking.20 Spontaneous coronary artery dissection (SCAD) is a rare type of CAD that causes myocardial infarction (MI) or sudden death. The mean age for SCAD is 42 years. Most cases are women (70% of all reported cases), and 30% of those women are in their third trimester of pregnancy or early postpartum period.21 The left anterior artery is the most common coronary artery affected by SCAD. The causes of SCAD are not clear. Conditions commonly associated with SCAD are CAD and the peripartum period. Some other risk factors include hypertension, connective tissue disorders (Marfan syndrome, Ehlers–Danlos syndrome), or vasculitis.21

KNOWLEDGE CHECK QUESTIONS 1. True or false: The thickness of the fibrous cap on a lesion determines its vulnerability to rupture. 2. True or false: The right anterior artery is most commonly affected by SCAD.

Clinical Manifestations Symptoms of IHD appear because the heart muscle is not receiving enough oxygenated blood. In 90% of the cases, it is a result of plaque buildup in the coronary arteries.22 However, not all patients can feel angina; asymptomatic ischemia is called silent ischemia.22 Angina pectoris (chest pain) is most often the first sign a person has when something is wrong. As the artery starts to narrow, the heart muscle does not receive the proper amount of oxygen; however, it is usually not diminished enough to cause the death of the cardiac muscle (infarct).22 Angina pectoris is a symptom that lasts up to 15 minutes. The pain is located under the sternum or in the precordial chest and is a discomfort that feels like constricting, squeezing, choking, or knifelike. The combination of increased myocardial demand and decreased myocardial perfusion is responsible for angina. The decline in perfusion is due to artery narrowing because of plaque, disrupted plaque, vasospasm, thrombosis, platelet aggregation, and embolization. There are three variants of

angina: stable angina, Prinzmetal angina, and unstable angina. The last one is the most dangerous and can lead to an AMI.22 Stable or typical angina is the most common form and results from the reduction of coronary perfusion to a critical level by plaque buildup. Because of the plaque buildup, the heart is vulnerable to further ischemia whenever there is an increase in the demand. Demand increases with physical activity or emotional excitement.22 This type of angina is relieved either by rest (reducing the demand) or by medications to dilate the coronary arteries (increase supply).22 Coronary spasms cause Prinzmetal or variant angina, as described in the “Pathology/Pathophysiology” section. Usually, there is an elevated ST segment on the ECG, indicative of ischemia. There may be plaque buildup with Prinzmetal angina, but attacks are unrelated to physical activity, heart rate, or blood pressure. Prinzmetal angina responds to vasodilators, such as nitroglycerin and calcium channel blockers.22 Unstable or crescendo angina is the same type of pain that occurs with stable angina, but with increasing frequency. This pain is present with little or no exertion, and may come on at rest and have a longer duration. The same factors that create stable angina cause unstable angina. However, unstable angina is usually an indication of an AMI.22 All three of these can lead to ACS. In ACS, there may be a rupture of the plaque (total occlusion), which results in an AMI. This type of AMI is ST elevation myocardial infarct (STEMI) and is transmural (Figure 16-4). Transmural MIs cause cellular death that involves the full or nearly full thickness of the ventricular wall in the area supplied by the occluded artery. In contrast, if there is a reduction in the blood flow, unstable angina occurs. This does not result in heart damage but is a warning sign. The subendocardial (nontransmural) infarct affects part of the ventricular wall in the areas supplied by the occluded artery and causes a non-STEMI.22

KNOWLEDGE CHECK QUESTIONS 1. True or false: Ischemia results in a depressed ST segment on an ECG. 2. True or false: Transmural MIs cause full-thickness cell death of the ventricular wall supplied by the occluded coronary artery.

Noninvasive Diagnostic Testing Several noninvasive tests can be performed to diagnose IHD. Some are more definitive than others. Usually, more than one test is needed. Listed below are the noninvasive tests that can be ordered by a physician.

Noninvasive Diagnostic Testing

I

aVR

V1

V4

II

aVL

V2

V5

III

aVF

V3

V6

II

FIGURE 16-4  Twelve-lead ECG showing an STEMI.

I

aVR

V1

V4

II

aVL

V2

V5

III

aVF

V3

V6

II

FIGURE 16-5  Hyperacute phase of AMI.

Twelve Lead Electrocardiogram One test that can be performed to detect heart muscle ischemia, injury, or an AMI is a 12-lead ECG.23 An ECG shows the electrical activity of the heart and produces a series of waves and complexes that look like spikes and dips. Approximately half of people who suffer from angina or silent ischemia have normal ECG readings.11 As the blood flow to the heart muscle diminishes, the muscle becomes ischemic and switches from using oxygen to produce energy, called aerobic metabolism, to producing

energy without oxygen, called anaerobic metabolism.23 This results in the muscle becoming acidotic. This acidosis can, if not reversed, cause cell injury and eventually death.23 Consequently, changes in the ECG occur. The early stage of an AMI may not be visible on an ECG. If visible, it shows as broadened, asymmetric, and peaked T waves.23 This is called the hyperacute phase, see Figure 16-5. Ischemia occurs next and results in electrical changes in the ischemic areas. Because of the electrical changes, there are ST

445

446

CHAPTER 16  Ischemic Heart Disease depressions and the T wave becomes inverted.23 If normal blood flow does not return, the heart muscle starts to suffer injury. The damage prevents the cells from repolarizing correctly. These cells remain more positively charged than normal. The abnormal repolarization usually causes ST elevations greater than 2 mm with a flipped T wave.23 This process is reversible with improved blood flow. If blood flow to the area does not improve, the muscle infarcts, or dies, an irreversible process. When heart muscle dies, there is no electrical activity. As a result, the ECG looks through the dead tissue to the tissue behind it. This results in the development of a permanent Q wave or a deeper-than-normal Q wave. This Q wave is called a pathologic Q wave, see Figure 16-6.23 The tissue surrounding the infarcted area still suffers from ischemia or injury. This keeps the ST segment elevated, and the T waves flipped.23 Analyzing ECG waves and complexes can detect other cardiac abnormalities. These abnormalities include enlarged heart chambers or inflammation of the pericardium. Review of an ECG can also check the medication effectiveness, monitor the location of implanted mechanical devices (i.e., pacemakers), and check device function.24

Exercise Stress Testing Patients who have some angina and a normal ECG at rest could still have IHD. Others with obvious symptoms

and suspicious ECG may not have IHD. In either case, these patients require an exercise stress test to diagnose the presence of IHD.25 An exercise stress test uses a treadmill or stationary bicycle to put stress the heart. The most common type of an exercise stress test has a patient walk on a treadmill using the Bruce protocol.25 In the Bruce protocol, the treadmill starts with a warmup phase; this is a slow speed. Every 3 minutes the treadmill speed and its incline increase. Each 3-minute interval is a stage (Figure 16-7).25 The test is over when the heart rate reaches 85% of its maximum heart rate that is determined by the patient’s age. Testing ends early when any of the following occur: ST-segment depressions, chest pain, certain heart arrhythmias (ventricular tachycardia or ventricular fibrillation), fatigue, or the patient wants to stop.11 During stress testing, certain vital patient assessments are made. These particular assessments appear in Table 16-4. Exercise stress tests are not 100% accurate and are incorrect approximately 10% of the time. A false-positive test indicates there is heart disease when there is no heart disease.11 A false-negative test indicates there is no disease when there is heart disease. When the heart has to work harder, it requires more oxygenated blood. The coronary arteries dilate. If IHD exists in the coronary arteries, they are not able to dilate as much, resulting in diminished blood flow and oxygen delivery to the heart, causing ischemia.25

I

aVR

V1

V4

II

aVL

V2

V5

III

aVF

V3

V6

II

Pathological Q waves

FIGURE 16-6  Pathologic Q waves.

Noninvasive Diagnostic Testing

FIGURE 16-7  Treadmill stress test. © ComStock/Stockbyte/Getty Images.

TABLE 16-4 Exercise Stress Test Patient Assessments Assessment

Explanation

Exercise capacity

Maximum amount of physical exertion a patient can sustain

ECG

Monitor for ST-segment depressions or arrhythmias

Heart rate

Heart rates increase due to decreased vagal tone and increased sympathetic outflow Monitor heart rate recovery following exercise

Blood pressure

Systolic blood pressure usually rises with increasing work rates Monitor for changes

Oxygen saturation

Assessing for abnormal exerciseinduced hypoxemia

Chest discomfort

Can be used as a criterion for diagnosis and prognosis

Pharmacologic (Chemical) Stress Test Exercise stress tests, using a treadmill, are the diagnostic test of choice for IHD. However, there are times when a patient is unable to walk on a treadmill.26 Physical limitations, such as back problems, joint disease, marked fatigue, unsteady gait, prior stroke, dizziness, or

shortness of breath, prevent the use of an exercise stress test.26 The primary medications for chemical stress testing include adenosine, dipyridamole, dobutamine, and regadenoson. These medications should mimic the effects of exercise on the heart and coronary arteries, and may reveal any underlying CAD. Adenosine dilates the coronary arteries and mimics what occurs during exercise. This drug dilates normal arteries more than stenotic arteries. The administration of adenosine is via an intravenous (IV) pump. This medication has a half-life of approximately 6 seconds. Adenosine increases the blood velocity and flow rate in normal vessels. However, the diseased artery is limited as to how much they can dilate, and this shows up as ischemia.26,27 Dipyridamole, brand name Persantine, has the same effect on the coronary arteries as adenosine. This medication is given over a 4-minute period through an IV as an IV push.26,27 Dobutamine is a positive cardiac inotrope and chronotrope, and it causes the heart rate to increase. The administration is through an IV with a pump. The amount administered is increased every 3 minutes until the heart rate reaches 85% of its maximum.26,27 Regadenoson is an adenosine analog and has the same effect on the coronary arteries as adenosine, but has a longer half-life. Administration is through the IV as an IV push.26,27

Echocardiogram An echocardiogram uses high-frequency sound waves, called ultrasound, to look at the heart.28 The sound waves originate in a probe placed on the chest wall over the heart. When the sound waves reach the heart, they bounce back or echo to the probe. The probe sends these echoes to a computer, which converts the echoes into real-time moving images of the heart.28 An echocardiogram can evaluate the heart’s wall size, wall function, valve function, blood flow, chamber size, and pumping function (Figure 16-8).28 A physician may also order a stress echocardiogram. This is used to look at the wall motion of the heart.29 When the heart muscle is ischemic, it cannot pump as well. In a stress echocardiogram, the patient has an echocardiogram or resting scan first.29 Then a chemical or treadmill stress test is performed. Following the stress test, the patient is re-scanned. The pre- and post-stress test scans undergo comparison. If the wall motion of the heart and ejection fraction (fraction of blood pumped from the heart with each beat) are less on the second exam, there is a possibility that the patient has CAD.29

Radiological Imaging Radiological imaging, also known as nuclear imaging, uses a radioactive isotope to evaluate blood flow in the heart.29 When the work of the heart increases, it requires more blood. The coronary arteries dilate

447

448

CHAPTER 16  Ischemic Heart Disease

FIGURE 16-8  Echocardiogram with and without Doppler. © kalewa/Shutterstock.

to increase the blood flow. Coronary arteries that have plaque in them are not able to dilate as much as normal arteries. This results in reduced blood flow to the heart.25 When the less-expensive diagnostic approaches are unreliable, radiological imaging is used.11 The radioactive isotopes used in radiological imaging are thallium, Cardiolite, or Myoview.29 An IV is used to inject the isotopes, and as they circulate in the body, they are taken up by the viable heart tissue. Because more blood circulates to the areas of the heart without diseased arteries, more isotopes appear in these areas during the scan.27 Radiological imaging is a three-step process. In the first step, the isotope is injected, and pictures are taken using a scanning camera; this is a resting scan. The camera rotates around the patient’s chest, stopping at specific intervals to take pictures. The camera is designed to detect the gamma radiation emitted by the isotope.29 After the scan, the pictures are sent to a computer for the physician to view and interpret. These images demonstrate coronary artery perfusion at rest. Next, the patient receives a stress test. The stress test is administered chemically or performed with a treadmill. One minute before the end of the stress test, the isotope is injected, again through the IV. The isotope needs to circulate for 1 minute before the stress test ends; therefore, it is important that patients inform the physician when they can endure only another minute.29 The third step is a repeat scan called the stress scan. A scan comparison

looks for any differences. If an area of the heart does not have any color present, there is no blood flow to the muscle in this field. Reversible ischemia shows when the resting scan has more color than the stress scan. If the resting scan and stress scan do not have any color, this indicates irreversible ischemia (Figure 16-9).30

Computed Tomography Another type of testing for IHD is computed tomography (CT) scanning. These are used to evaluate IHD.11 Two types of CT scans can be used to assess for IHD: calcium-scoring CT scan and the coronary CT angiography (CCTA). The calcium-scoring CT scan looks at the coronary arteries and detects any calcium. The presence of calcium correlates well with the presence of IHD. The calcium score indicates IHD. If the score is low, it is unlikely the patient has IHD. A high score does not mean the patient has IHD, but it is an indication for additional testing.11 This type of diagnostic test is used primarily for risk stratification of asymptomatic patients. CCTA scans are also used to visualize the coronary arteries for patients with acute or chronic chest pain. However, CCTA scans are not as accurate as the invasive coronary angiograms and are only for diagnosing, not treatment, discussed in the invasive section of this chapter. Other types of newer CT techniques include electron beam CT and multidetector CT.11

Diagnostic Testing—Invasive

FIGURE 16-9  Coronary angiograms and nuclear scan images. Reproduced with permission from Pijls N. (2004). Non-invasive testing is not specific enough: why and how to obtain objective signs of ischemia in the cath lab. Cath Lab Digest, 12(10), 12–20. https://www.cathlabdigest.com/articles/Non-invasive-Testing-Not-Specific-Enough-Why-and-How-Obtain-Objective-Signs-Ischemia-Cath-L.

KNOWLEDGE CHECK QUESTIONS 1. True or false: Electrical changes due to ischemia can invert the T wave on an ECG. 2. True or false: The ventricular wall movement is assessed using nuclear imaging.

Diagnostic Testing—Invasive Based on the information collected in the noninvasive testing, an individual may need to have a more invasive test called a left heart catheterization. This type of catheterization shows coronary angiograms. This test is invasive and, therefore, has more risks of complications.

Coronary Angiograms Although invasive, the cardiac catheterization is the gold standard for diagnosing and treating coronary vessel occlusions. Indications for a coronary angiogram include a positive result from one or more of the noninvasive tests, inconclusive noninvasive tests, or during an

AMI.11 With this procedure, the physician can directly visualize the coronary arteries and assess the pumping function of the left ventricle.11 For this procedure, the physician accesses the artery in the groin via the femoral artery or in the wrist via the radial artery. Usually, the right leg or right wrist is used. Figure 16-8 shows the sites for catheter entry. Once the artery is accessed, the physician uses a small wire and a small hollow tube called a catheter to advance through the artery to the opening of the coronary artery, the coronary artery ostium. This is called cannulating the coronary artery ostium. The next step is to inject the contrast medium (dye) into the coronary artery. This injection is the coronary angiogram (Figure 16-10).11 Coronary angiogram observation occurs under X-ray; the physician watches the contrast as it flows through the coronary arteries. Narrowing of an artery on X-ray represents stenosis and is a lesion. The basis for treatment is the severity of the lesion, the number of arteries with lesions, and location of lesions.11 Treatments can range from medications to percutaneous coronary intervention (PCI) to open-heart surgery. Figure 16-11 shows a coronary angiogram before and after a PCI.

449

450

CHAPTER 16  Ischemic Heart Disease

FIGURE 16-10  Sites used for arterial entry to perform a cardiac catheterization. © Alila Medical Media/Shutterstock.

FIGURE 16-11  Coronary angiograms before and after PCI of a

coronary lesion.

© KellyNelson/Shutterstock.

Coronary angiograms will not always be definitive. There are times when angiograms do not provide the information needed to make a decision about the proper treatment of a lesion. When this occurs, other tools are available during a heart catheterization that assists the physician in making a decision. Three tools help in the decision-making process in the catheterization lab.31 They are the fractional flow reserve (FFR) wire, IntraVascular UltraSound (IVUS), and optical coherence tomography (OCT).

Fractional Flow Reserve Fractional flow reserve (FFR) calculates blood flow

across a stenosis. The basis for this test rests on the three principles of coronary pressure and flow. The first principle is that aortic pressure is transmitted through

normal coronary arteries without any loss; even to the distal regions of the vessels.31 The second principle is narrowing of the artery lumen results in resistance to blood flow. This resistance causes a drop in pressure in the artery distal to the lesion. This drop is used to calculate the resistance. The velocity of the blood flow through the lumen of an artery increases as the lumen size decreases. As a result, the pressure across the lesion decreases.31 The third principle involves the morphology of the stenosis. A standard coronary angiogram cannot quantify the resistance created by the lesion morphology.31 The FFR wire measures the pressure across the lesion or translesional pressure using a 0.014-inch pressure sensor guide wire. Measuring the pressure before and after the lesion quantifies the effect of the stenosis on blood flow.31 Adenosine (IV or intracardiac [IC]) is administered to increase the blood in the artery, called hyperemia.31 The FFR wire uses a ratio of the pressure distal to the lesion compared to the pressure in the aorta; normally, this is a 1:1 ratio. Figure 16-12 shows a schematic of this principle. If the ratio is below 1, this represents the percentage reduction of normal flow (i.e., if the ratio is 0.80, the artery transmits 80% of the expected normal flow).31 The FFR versus angiography in multivessel evaluation (FAME) trial demonstrated that a lesion with a ratio below 0.80 needs repair. With a lesion having a ratio greater than 0.80, medical treatment is the best option.32 The FAME study also demonstrated that use of FFR to guide treatment reduced cost and was superior to coronary angiogram guided treatment.32

Diagnostic Testing—Invasive

FIGURE 16-12  The flow of blood increases distal to the lesion in the vessel, decreasing the pressure across the lesion. © Fouad A. Saad/Shutterstock.

IntraVascular UltraSound/Optical Coherence Tomography While FFR is perfect for physiologic lesion assessment, it cannot give vessel size, stent expansion, stent apposition, lesion length, or plaque morphology. To assess these characteristics, intravascular ultrasound (IVUS) or optical coherence tomography (OCT) is the proper tool.31 An IVUS or OCT catheter can provide images from within the coronary artery. With IVUS or OCT, the physician can accurately quantify the dimensions of the vessel, the length of the lesion, the composition of coronary arteries, and plaque morphology. The images returned from the IVUS or OCT catheter can give precise details with good resolution.31 The standard coronary angiogram cannot provide all this information that is helpful in the selection of the correct stent size. After stent implantation, information from the IVUS or OCT is used for the assessment of the stent’s appropriate placement, proper size, full expansion, and the complete apposition of the struts to the vessel wall.31 IVUS catheters have an ultrasound probe on the tip. This probe uses the same technology as the ultrasound probe described in the “Echocardiogram” section. The IVUS catheter fits over an angioplasty guide wire that is already in the artery distal to the lesion. The IVUS probe is advanced distal to the lesion. A recording of the images occurs as the probe is pulled back through the lesion.31 The physician can view the pictures on the IVUS computer (Figure 16-13). The recorded images allow the physician to measure the minimal lumen

FIGURE 16-13  IVUS image. Cath Lab Digest. 2013;21(4):28–30.

diameter, reference vessel diameter, and vessel area.31 The selection of the stent size is based on the reference vessel size. Using IVUS after a stent is in place has resulted in superior stent outcomes, reduced abrupt closure, and lower restenosis; all of these are a major advance in interventional cardiology.31 The OCT catheter contains a single optical fiber that emits infrared light with a wavelength between 1,250 and 1,350 nm.33 Resolution is better with OCT than with IVUS; however, tissue penetration is better with

451

452

CHAPTER 16  Ischemic Heart Disease

FIGURE 16-14  OCT image. © BSIP/UIG/Universal Images Group/Getty Images.

IVUS than with OCT.33 Figure 16-14 shows an image from an OCT catheter. Red blood cells can interfere with the light from the OCT catheter. Therefore, the vessel fills with contrast when obtaining images. The tip of the OCT catheter is in a place distal to the lesion and scans the lesion as the physician pulls it back.33 The catheter measures the echo time delay and the signal intensity after it is reflected from the coronary wall structures.33 Physicians can obtain the same information from an OCT catheter as an IVUS catheter. See the “IVUS” section for this information.

KNOWLEDGE CHECK QUESTIONS 1. True or false: Access for a left heart catheterization is through the femoral vein. 2. True or false: The most appropriate treatment for a FFR of 50% is angioplasty.

Treatment and Management The best treatment for a patient with IHD is a decision made by the physician and the patient. The physician takes into consideration the patient history, current medical condition, and the results from the heart catheterization. Some of these factors are diabetes, heart failure, the number of arteries affected, location and severity of the lesion(s), and other comorbidities.34 Studies have shown that if a patient is diabetic and has lesions in three or more vessels, coronary artery bypass grafting (CABG) is the best option. Also, if the lesion is in the left main coronary artery, then CABG is the best choice.34 The treatment options for IHD include medical management, invasive management, or surgery.

Pharmacologic Management If the physician determines the patient has mild IHD, medical management is best. Medical management includes certain medications and lifestyle changes. These

lifestyle changes help to prevent the progression of the disease (see the section on “Prevention”).34 When lifestyle changes are not enough, the physician prescribes certain medication to help (Table 16-5). These medications help to reduce the risk of heart attack, stroke, and heart failure, which helps lessen the likelihood of death. The medications prescribed are antianginal medications, anticoagulation medications, antihypertensives, and cholesterol-lowering medications. Antianginal medications help with angina (chest pain). One way to reduce angina is to reduce the myocardial oxygen demand by using drugs that block the beta-1 receptors in the heart. These beta blockers slow the heart rate. Another method to reduce angina is to reduce the resistance the heart has to work against to open the heart valves. This is afterload, and the medications that reduce afterload are calcium channel blockers. A third way of alleviating angina is to use nitrates. Nitrates dilate the coronary arteries and thus increase the amount of blood flow to the heart.34 Anticoagulant medications help thin the blood and reduce the risk of clot formation (thrombus). Aspirin is an anticoagulant that is available without a prescription and is available in low dose (50 mg) for this purpose. Physicians use aspirin for patients with stable CAD. For unstable CAD, platelet P2Y12 inhibitor is used (clopidogrel, brand name Plavix).34 Antihypertension medications help reduce high blood pressure. Some people have high blood pressure due to water retention. This may be due to intake of too much sodium. For these individuals, a diuretic helps remove the excess sodium and water from their body, thereby reducing the blood pressure.35 Angiotensin II is a potent vasoconstrictor. Angiotensin-converting enzyme (ACE) inhibitors prevent an enzyme in the kidney from converting angiotensin I to angiotensin II.35 All muscles need calcium to contract. Calcium channel blockers prevent calcium from entering the muscles in the heart and blood vessels. This leads to a drop in the heart rate and vasodilatation, thus lowering the blood pressure.35 The largest class of cholesterol-lowering medications is the statins. Statins work in the liver by preventing the formation of cholesterol, which lowers the cholesterol in the body. They work mainly on the bad cholesterol (LDL), but may also raise the good cholesterol (HDL) and lower triglycerides. People taking these medicines may have muscle pain and need to have their liver functions regularly tested.36

Angioplasty If determined during a heart catheterization that the patient has severe IHD or is having an AMI, percutaneous coronary angioplasty (PCI) of the artery or arteries is necessary. Initiation of a PCI occurs following the coronary angiogram. There are certain situations where the physician may wait to perform

Treatment and Management

TABLE 16-5 Medical Treatment for IHD Medication Class

Medication Type

Examples of Medication

Mechanism of Action

Antianginal drugs

Beta blockers

Carvedilol (Coreg) Atenolol (Tenormin)

Decreases heart rate and heart’s demand for oxygen.

Calcium channel blockers

Verapamil (Calan) Amlodipine (Norvasc)

Decreases afterload and prevents coronary artery spasm.

Nitrates

Nitroglycerin

Dilates coronary arteries.

PGHS-1 inhibitor

Aspirin

Prevents thrombosis.

P2Y12 inhibitor

Clopidogrel (Plavix)

Interferes with platelet aggregation.

Diuretics

Furosemide (Lasix) Spironolactone (Aldactone)

Reduces the amount of water in the body.

ACE inhibitors

Benazepril (Lotensin) Lisinopril (Prinivil)

Relaxes blood vessels and reduces the workload on the heart.

Calcium channel blockers

Verapamil (Calan) Amlodipine (Norvasc)

Decreases heart rate and causes vasodilation.

Statins

Simvastatin (Zocor) Atorvastatin (Lipitor)

Prevents the formation of cholesterol in the liver.

Anticoagulant drugs

Antihypertensive drugs

Cholesterol-lowering drugs

the PCI or stage the PCI. The basis for this decision is the patient’s condition. The contrast used in a heart catheterization can harm the kidneys by causing contrast-induced nephropathy (CIN). This compromises kidney function, causing elevated blood urea nitrogen (BUN) and creatinine levels. Accordingly, the PCI can be delayed for a few days, allowing time for the kidneys to recuperate. The contrast needs to be flushed out with IV fluids following heart catheterization. Giving fluids to patients with renal dysfunction before a heart catheterization will help to reduce the chance of CIN.37 If there are multiple lesions, the procedure is staged, and this helps to reduce the likelihood of CIN. In some patients, the treated artery closes back down. This is restenosis and has been a major problem with PCIs since its inception. After an artery undergoes repair, the vessel grows new tissue in the repaired area. This new tissue consists of healthy cells from the lining of the arterial wall (endothelium) and is desirable. This new tissue allows the blood to flow smoothly and reduces the risk of thrombus development. In some cases, scar tissue may form underneath the new healthy lining. If the scar tissue becomes too thick, it obstructs the blood flow and causes restenosis.38 All invasive procedures require the use of anticoagulants to prevent the formation of clots on the equipment while in the body. In the early days of angioplasty, the anticoagulant used was unfractionated heparin (heparin). Heparin is an antithrombin agent that inactivates thrombin.39 Heparin and drugs derived from heparin are considered indirect thrombin inhibitors. One

complication of using heparin over long periods is the development of heparin-induced thrombocytopenia with or without thrombosis syndrome (HIT[TS]). This syndrome causes thrombi to form even when receiving heparin; it rarely occurs during PCIs.39 Today, direct thrombin inhibitors are used during PCIs. The most commonly used is bivalirudin.39 This drug does not carry the threat of HIT(TS) but does not have a reversal agent like heparin. The half-life of bivalirudin is 25 minutes.39 There are several types of angioplasty. Each one follows the same catheter introduction as described for the coronary angiogram.

Plain Old Balloon Angioplasty This procedure is useful on the soft plaque. The plaque morphology is determined by using IVUS or OCT, as described earlier. During this procedure, a small (0.014 inches in diameter) coronary guide wire is advanced into the coronary artery with the lesion. The guide wire continues to be advanced until it is at a distal point in that coronary artery. The physician uses a coronary balloon catheter that matches the size of the reference diameter and the length of the lesion (Figure 16-15). The balloon catheter loads onto the coronary guide wire and advances to the lesion. The balloon has two radiopaque markers. One is on the proximal end, and the other is on the distal end of the balloon. The physician uses these markers to place the balloon to cover the lesion before inflating. If the balloon inflation occurs in the wrong place, it causes damage to healthy tissue.

453

454

CHAPTER 16  Ischemic Heart Disease

Artery with plaque

Catheter with uninflated balloon inserted

Balloon inflated, plaque compressed

FIGURE 16-16  Rotablator burr. Image courtesy of Boston Scientific. © 2019 Boston Scientific Corporation or its affiliates. All rights reserved.

Widened artery

FIGURE 16-15  Balloon angioplasty.

The balloon must cross the lesion before inflation. If the balloon is unable to cross the lesion, a smaller balloon is tried. The appropriate balloon is the one that crosses the lesion. When smaller balloons are used, several balloons are needed to repair the artery.40 Once the balloon is in place, it is inflated using a device called an indeflator. The indeflator pushes a contrast/saline mixture into the balloon, causing the balloon to inflate. The balloon puts pressure on the plaque in the lesion, compressing and fracturing the inside vessel walls. The pressure exerted on the vessel wall is measured in atmospheres (1 atm equals 15 psi). The amount of pressure required depends on the lesion and the physician.40 Balloon angioplasty carries a 40% chance of restenosis.38

speed of the burr and allows manipulation of the catheter. The drive unit attaches to a flush solution through an irrigation port. The flush mixture usually contains 1,000 units heparin, 2 mg nitroglycerin, and 5 mg verapamil in 500 mL of normal saline.40 Using a pressure bag on the saline mixture provides a continuous flow to the catheter. The mixture lubricates the catheter, reduces the chance of spasms, and reduces clot formation. The rotational atherectomy device is pneumatic and uses pressurized nitrogen gas.40 The burr sizes range from 1.25 to 2.38 mm. The larger the burr, the larger the guide catheter has to be. Rotational atherectomy removes calcified plaque by grinding it away. After grinding the plaque away, a stent is placed. The largest burr used should be smaller than the reference lumen diameter. Several burr sizes are often required to grind away the plaque. This is done in increments of 0.5 mm to reduce the risks of complications.40 The manufacturer recommends a temporary pacemaker for the patient before using the rotational atherectomy device.40

Rotational Atherectomy

Stents

Rotational atherectomy uses a catheter with an

In most cases after a plain old balloon angioplasty (POBA) or rotational atherectomy, the artery is stented (Figure 16-17). A stent is a wire mesh tube that acts as scaffolding for the artery to help keep it open. Stents are pre-mounted on a balloon catheter.34 The stent catheter has the same characteristics as the balloon catheter, and inflation is the same. Stent selection requires matching the size of the reference vessel and length of the lesion. After the balloon deflation of the stent catheter, the catheter is removed, leaving the stent behind.41 Stents

oval-shaped burr resembling a football. Attached to the front portion are crushed diamonds (Figure 16-16). The burr rotates at high speeds (150,000 rpm) to grind hard plaque away. The plaque morphology is determined using the IVUS or OCT. Rotational atherectomy requires a 0.009-inch diameter coronary guide wire advanced down the coronary artery with the lesion. The guide wire advances to a distal point in the coronary artery. The burr catheter attaches to a console, which displays the

Cardiac Rehabilitation the cell division. These drugs all have names ending in “olimus.”43 As with BMS stents, there is a risk of stent thrombosis, and because of this, DAPT is required. Because the drugs do not differentiate between healthy tissue and scar tissue, it takes a long time for the healthy endothelial cells to cover the DES. For this reason, the patient uses DAPT longer. According to the 2011 ACCF/AHA/SCAI Guideline for PCI, after a DES has been implanted, DAPT must continue for 12 months.44

Coronary Artery Bypass Grafting

FIGURE 16-17  A stent catheter placed in the coronary artery with

the lesion. The balloon is inflated and then deflated, leaving the stent in the artery.

increase the structural integrity of the coronary arteries and become incorporated into the coronary arteries through endothelialization.

Bare-Metal Stent As the name implies, these stents consist of metal without any coating. These were the first stents made. The invention of stent reduced the restenosis rate to 25%. Using a bare-metal stent (BMS) increases the risk of clot formation on the stent. To prevent this, the patient has to take dual antiplatelet therapy (DAPT). DAPT consists of taking two blood thinners for 1 month. These are aspirin and a platelet P2Y12 inhibitor (such as clopidogrel).34 After 1 month, the endothelial cells cover the stent, reducing the risk for clots.34 If the patient goes 12 months without an event, it is rare for restenosis to develop.34

Drug-Eluting Stents Drug-eluting stent (DES) material is the same as the

BMS. However, they have a drug on them to reduce the restenosis rate. The restenosis rate associated with the use of DESs is 5%.42 DESs have three basic parts: a stent platform, a polymer, and an anti-restenotic drug.43 The polymer must be non-thrombotic, non-inflammatory, and nontoxic to cells, and should encourage arterial healing by re-endothelialization.43 Different types of medicines are used with the stents. Paclitaxel is a cancer drug made from the Pacific Yew trees. This medication prevents restenosis by stopping the cells from dividing. The other type of drug prevents restenosis by slowing

Some patients with IHD need to have surgical management with CABG. Patients considered for CABG have one or more of the following: diabetes, severe lesions, lesion in the left main coronary artery, or disease involving two or three coronary arteries.34 A CABG entails the creation of a bypass (detour) around the blockage. To create the bypass, either the saphenous vein from a leg (SVG) or the left internal mammary artery (LIMA) from the patient’s chest becomes the bypass graft.34 The LIMA grafts have been proven to last the longest. The radial artery in the arm may also serve as a graft. The number of bypasses varies depending on the number of blockages.34 CABG operations require general anesthesia and a heart–lung machine to maintain circulation. The typical hospital stay post CABG is 4–7 days. Full recovery from the surgery can take up to 3 months.34 Recently, a new method of performing CABG has been developed. It is the minimally invasive direct coronary artery bypass (MIDCAB). This technique does not require stoppage of the heart. Therefore, the heart–lung machine is not used. The MIDCAB is less invasive than the CABG and does not require the surgeon to cut through the breastbone (sternum).34 MIDCAB requires only a small incision between the ribs to operate on the blocked artery. The entire procedure occurs while the heart is beating, and requires only a 3-day hospital stay.34 This approach is less invasive and has a lower length of stay. If the patient has more than two blocked arteries, this technique is not utilized.

Cardiac Rehabilitation After a PCI or CABG, the patient is referred to cardiac rehabilitation.45 Cardiac rehab is a supervised program that helps improve the lives of people diagnosed with heart problems. Almost every person with IHD can benefit from cardiac rehab. The cardiac rehab team may include doctors, nurses, exercise specialists, physical and occupational therapists, dietitians or nutritionists, and psychologists or other mental health specialists.45 Cardiac rehab teaches the patient the proper way to exercise. Through education, counseling, and training, the patient can understand the heart condition, cope with stress, and deal with fears about the future. The cardiac rehab team works together to develop

455

456

CHAPTER 16  Ischemic Heart Disease a program designed to meet the individual patient’s needs. The program shows the patient how to exercise safely and strengthen their muscles, and improve their stamina.45

TABLE 16-6 Controllable Risk Factors and Strategies Risk Factor

Control Strategies

Hypertension

Reduce stress Reduce sodium intake Weight loss Smoking cessation Exercise Diet Medications

Hyperlipidemia

Diet Exercise Medications

Diabetes/prediabetes

Diet Exercise Weight loss Decrease sugar intake Medications

Smoking

Smoking cessation program Medications Reduce stress Behavior modification

Overweight/obese

Diet Exercise Stress reduction Reduce sugar intake Weight loss program

Sedentary lifestyle

Exercise program

Unhealthy diet

Dietician consultation Healthy diet

KNOWLEDGE CHECK QUESTIONS 1. True or false: The best treatment option for a patient with diabetes and lesions in three or more vessels is CABG. 2. True or false: An inflated angioplasty balloon contains air. 3. True or false: The bypass vessel used in a CABG is either the saphenous vein from a leg or the left internal mammary artery from the patient’s chest. 4. True or false: The MIDCAB procedure for performing a CABG requires a heart–lung machine to maintain circulation. 5. True or false: Cardiac rehabilitation is a management strategy used only for post-CABG patients. 6. True or false: Patients who have completed a cardiac rehabilitation program will have improved stamina.

Risk Factors The risk factors for IHD include those that are controllable and those that are uncontrollable. Table 16-6 lists controllable risk factors with strategies to control them.

KNOWLEDGE CHECK QUESTIONS 1. True or false: A sedentary lifestyle increases the risk for the development of IHD. 2. True or false: Diabetes is an uncontrollable risk factor for IHD.

Prevention The best treatment for IHD is prevention. The first step in prevention is for the patient to identify the risk factors and take appropriate action to eliminate the controllable factors, and minimize the effects of the uncontrollable risk factors (see risk factors in the “Introduction” section).46 The more risk factors a patient has, the higher the risk for IHD.46

The effects of the controllable risk factors for IHD are reduced by adopting a healthy diet consisting of vegetables, fruits, whole grains, fat-free or low-fat dairy products, and protein foods.46 Protein food includes lean meats, poultry without skin, seafood, processed soy products, nuts, seeds, beans, and peas.46 Avoid or reduce sodium (salt), added sugars, solid fats (saturated fat and trans fatty acids), and refined grains. Eating whole grains increases nutrient and fi ­ ber intake.46 Adopting a healthy diet also helps to reduce obesity and hypertension. However, sometimes diet is not enough to control IHD and medication is necessary. Exercise in conjunction with a healthy diet helps to reduce weight and blood pressure and control diabetes.46 Smoking cessation reduces the risk of IHD. Smoking damages and constricts blood vessels, increasing the risk of IHD. Also, secondhand smoke needs to be avoided.47 There are numerous smoking cessation programs and medications to aid in the smoking cessation process.

Complications A reduction in stress can reduce the risk of IHD. Research shows that stress from anger or an emotional event can induce a heart attack.45 Stress causes a person to overeat and increases alcohol consumption and tobacco use. Eating right, getting exercise and relaxation therapy, or taking stress management classes helps reduce stress.45

TABLE 16-7 Complications from Diagnostic Catheterization Injury

Explanation

Vessel injury

Injury to the catheterized artery or vein (both arm and leg) occurs in 0.5–1.5% of patients.

Site bruising

Bruising with skin discoloration at the site occurs in 1–5% of patients.

Reaction to contrast medium

Contrast may cause transient nausea and vomiting in 3–15% of patients, itching or hives in 1–3%, and a life-threatening allergic reaction in approximately 0.2%. Many physicians will give Benadryl as a precaution.

CIN

The kidney function is compromised by excessive amounts of contrast, causing elevated BUN and creatinine levels. Extra IV fluids will flush out the contrast.

Infection

Rarely occurs.

Heart attack, stroke

Within 24 hours of catheterization, this occurs in only 0.2–0.3% of patients.

Death

Perforation of the heart or surrounding vessels, cardiac arrhythmia, or anaphylactic shock due to contrast medium can cause death.50

KNOWLEDGE CHECK QUESTIONS 1. True or false: Diet and exercise can reduce the risk of IHD. 2. True or false: Stress, alone, cannot cause a heart attack.

Complications Diagnostic testing for IHD has a risk of complications. Exercise and chemical stress testing have very few complications. There is a 1-in-5,000 chance of a person having a heart attack or dying during the exercise test.48 Patients commonly develop arrhythmias, which normally subside with rest. If arrhythmias persist, the patient is monitored and receives prescribed medication. Hypotension may occur during testing, causing the patient to feel lightheaded or dizzy. This usually goes away when the patient stops exercising.48 The chemical stress test may lead to jitteriness, wheezing, shortness of breath, and other asthma-like symptoms. These symptoms may last several hours, can be severe, and require treatment.48 The use of radioactive contrast may cause an allergic reaction requiring medical treatment.49 Diagnostic cardiac catheterization is an invasive procedure and as a result carries an increased risk of complications. The possible complications appear in Table 16-7. The PCI carries all the same complications discussed in the “Diagnostic Cardiac Catheterization” section. Also, PCI complications are listed in Table 16-8. Individuals who are over the age of 65, have chronic kidney disease, have extensive heart disease with significant coronary artery blockages, or are in shock have a higher risk of complications from PCI. The more invasive the procedure, the more complications there can be. Following CABG surgery, there is usually some inflammation involving the lung and pericardium; this is from the incision in the pericardium. It is usually mild, but may require some treatment. The presence of comorbidities, such as diabetes kidney disease, lung disease, or peripheral arterial disease, increases the risk for complications following CABG surgery.51 Complications involving memory loss and problems with concentration may occur with older patients. The risk for complications increases when the

TABLE 16-8 PCI Complications Complication

Cause

Discomfort and bleeding at the catheter insertion site

Insertion of catheter

Blood vessel damage

Catheter

Cardiac arrhythmia (irregular heartbeat)

Irritation by catheter

The need for emergency CABG (40 years) ƒƒ Anticoagulant deficiencies (antithrombin, protein ƒƒ

C, protein S, plasminogen, heparin cofactor II) and combination anticoagulation deficiencies Antiphospholipid antibody syndrome ƒƒ Behcet disease (systemic vasculitis) ƒƒ Blood type A ƒƒ Burns ƒƒ Central venous catheterization ƒƒ Chemotherapy ƒƒ Congestive heart failure ƒƒ COPD ƒƒ Diabetes ƒƒ Dysfibrinogenemia and high fibrinogen ƒƒ Factor V Leiden mutation from activated protein C ƒƒ resistance Family history ƒƒ Fractures and presence of orthopedic casts ƒƒ Hemolytic anemias ƒƒ

High-dose hormone replacement and tamoxifen ƒƒ Hospitalized patients with chronic liver disease ƒƒ Increased travel time ƒƒ Intravenous drug abuse ƒƒ Lupus anticoagulant (SLE, AIDS) ƒƒ Major surgery ƒƒ Microalbuminuria (>30 mg/24 hours) ƒƒ Myocardial infarction ƒƒ Obesity ƒƒ Oral contraceptive use ƒƒ Phenothiazines ƒƒ Polycythemia, thrombocytosis, sickle cell disease, ƒƒ

and multiple myeloma Pregnancy ƒƒ Previous history of DVT or PE ƒƒ Prothrombin gene mutation (prothrombin G20210A ƒƒ mutation) Sedentary lifestyle, reduced mobility ƒƒ Spinal cord injury ƒƒ Venography ƒƒ

A major complication of PE is due to the therapy that treats the embolism. Anticoagulation therapy and thrombolytic therapy both increase the risk of bleeding, including intracranial hemorrhage.

Suspected PE

Clinical pretest probability/Prediction rule

Diagnostic Testing Diagnosis of PE begins with an assessment of clinical pretest probability (CPTP) based on the combination of individual symptoms, signs, and common tests evaluated using prediction rules (Table 17-3) or clinical judgment. The primary goal of diagnostic testing for PE is to identify patients who would benefit from treatment.3 Every patient for whom PE is initially considered does not need testing for PE, a convincing alternative diagnosis may subsequently be found.3 Diagnostic management algorithms are used to exclude PE without the need for imaging tests in a proportion of patients. These algorithms begin with the CPTP, followed by a D-dimer blood test or a computed tomography pulmonary angiography (CTPA).10 See Figure 17-8.

D-Dimer D-dimer is a degradation product of cross-linked fi-

brin, and therefore, levels are increased in the setting of thrombosis of any type. Plasma levels of D-dimer increase not only in the setting of venous thrombosis but also in many other conditions, including myocardial

PE unlikely

PE likely

D-dimer test

Positive test results (>500 mcg/L or ageadjusted threshold)

Normal test results

Negative PE excluded

CTPA Positive PE confirmed

FIGURE 17-8  Diagnostic testing algorithm for PE.

infarction, pneumonia, sepsis, trauma, surgery, cancer, and inflammation. Thus, D-dimer testing for VTE or PE is very sensitive, but the test is nonspecific.4 The test is inappropriate to “screen out” PE in patients who

Pulmonary Embolism have not been evaluated clinically because the high frequency of false positive results will increase, rather than decrease, the need for additional testing.3 A negative D-dimer in a low clinical probability patient does reduce the risk of PE to approximately 1% (when followed for 3 months), allowing such patients to be discharged without further investigation.

Computed Tomographic Pulmonary Angiography Since the introduction of multidetector computed tomographic (MDCT) angiography with high spatial and temporal resolution and quality of arterial opacification, computed tomographic (CT) angiography has become the method of choice for imaging the pulmonary vasculature in patients with suspected PE.8 The

computed tomographic pulmonary angiography (CTPA)

outlines the thrombi in the pulmonary arteries with intravenous contrast medium (Figure 17-9). The newest generation of CT scanners can image small peripheral emboli. Six-order branches can be seen with resolution superior to that of conventional invasive contrast pulmonary angiography.7 CT venography is a simple method for diagnosing DVT in patients with suspected PE, as it can be combined with CTPA in a single procedure, using only one intravenous injection of contrast medium. However, because CT adds a significant amount of irradiation, ultrasonography is appropriate instead of CT venography, if indicated.8 CTPA can lead to contrast-induced nephropathy and substantial radiation exposure. Allergic reactions to contrast medium are also possible.

Pulmonary Angiography Imaging Pulmonary angiography has for decades remained the ‘gold standard’ for the diagnosis or exclusion of PE but is rarely performed now as less-invasive CTPA offers similar diagnostic accuracy.8 When performed carefully and

FIGURE 17-9  CTPA showing normal pulmonary vessels. © windcatcher/iStock/Getty Images.

completely, a positive pulmonary angiogram provides virtually a 100% certainty of pulmonary arterial blood flow obstruction. A negative pulmonary angiogram similarly provides greater than 90% certainty that PE does not exist. Pulmonary angiography is more often used to guide percutaneous catheter-directed treatment of acute PE. Digital subtraction angiography requires less contrast medium than conventional cineangiography and has excellent imaging quality for peripheral pulmonary vessels in patients who can hold their breath; it is less useful for imaging of the main pulmonary arteries, due to cardiac motion artifacts.8 Pulmonary angiography is useful as a secondline imaging technique if previous studies have been nondiagnostic and clinical suspicion remains high. It is useful if a patient is unable to tolerate a CT scan. Pulmonary angiography carries a low morbidity/mortality rate, related more to the severity of the clinical presentation than the test itself. Its limitations include moderate to poor interobserver reliability, a risk of renal injury from contrast load, and missing subsegmental emboli. Despite it being a highly accurate investigation, it is rarely performed.9

Ventilation–Perfusion Scan Imaging Ventilation–perfusion (V/Q) scanning is an established

diagnostic test for suspected PE. The V/Q scan, also known as V/Q scintigraphy, does not cause allergic reactions, as does diagnostic tests that require intravenous contrast.8 This imaging test is a second-line diagnostic test for patients who cannot tolerate intravenous contrast.7 The perfusion scan utilizes the intravenous injection of radiolabeled macroaggregated albumin particles into a peripheral vein. In areas of normal blood flow in the lungs, the albumin particles lodge in a fraction of the perfused small vessels. When a clot obstructs blood flow within the pulmonary arterial system, the perfusion scan shows decreased blood flow. See Figure 17-10. The perfusion scan is combined with a ventilation study that utilizes a radiolabeled inhaled gas such as xenon-133- or Tc-99m-labeled aerosols, or Tc-99-labeled carbon microparticles. The V/Q scan exploits the unique pulmonary arterial segmental anatomy. Each bronchopulmonary segment receives blood from a single end artery. Occlusive thrombi affecting individual pulmonary arteries, therefore, produce characteristic lobar, segmental, or subsegmental peripheral wedge-shaped defects with the base projecting to the lung periphery.17 The combination of ventilation and perfusion studies increases the specificity of the test. With acute PE, ventilation is expected to be normal in hypoperfusion segments.8 Therefore, the diagnosis of PE depends on identifying the V/Q mismatch. A normal V/Q study excludes PE with the same degree of certainty as a negative pulmonary angiogram. A “high-probability” V/Q study establishes the diagnosis. A nondiagnostic V/Q study, on the other hand, is not

473

474

CHAPTER 17  Pulmonary Vascular Diseases

Radiologic Imaging

FIGURE 17-10  Perfusion scan of lungs with PE. The embolism

shows in the left upper lobe.

© ISM/Centre Jean PERRIN/Medical Images.

an acceptable end point in the workup for pulmonary thromboembolism and must be further followed up with another definitive test when the diagnosis remains unclear.5 For patients with contraindications to CTPA, including contrast allergy, renal disease, and pregnancy, V/Q scanning may be the preferred imaging modality for the evaluation of possible PE.18

Magnetic Resonance Pulmonary Angiography Magnetic resonance pulmonary angiography (MRPA) may provide an important safer alternative to CTPA because it is free of long-term cancer risks from ionizing radiation and has an overall decreased risk of complication from contrast material adverse reaction.19 The conclusion of a large-scale clinical trial studying the use of MRPA to diagnose PE is that it should be considered only by centers that routinely perform it well and only for patients for whom standard tests are contraindicated.20

Venous Doppler Doppler ultrasonography is the most widely used modality for evaluating patients with suspected DVT and PE, because of its accuracy in detecting proximal thrombi, noninvasiveness, and wide availability. When used in combination with a CPTP, ultrasound examination is accurate in predicting the need for anticoagulation. A normal ultrasound study in a high-probability patient requires additional investigations before the possibility of DVT and PE can be ruled out. There are certain limitations on the use of Doppler ultrasonography. These limitations include operator accuracy, inability to differentiate between old and new thrombus, and specific site limitations, such as the detection of a DVT in the pelvic veins or small vessels of the calf. Another obstacle limiting the use of Doppler ultrasonography is the presence of significant obesity or edema. A positive Doppler allows diagnosis of thromboembolism, while a negative study mandates further investigation.9

Initial CXR findings of patients with PE are most often normal. Later, an initially normal CXR may deteriorate to atelectasis, or develop a pleural effusion or elevation of the hemidiaphragm. Also, some cases may demonstrate focal infiltrates that simulate infection (especially in the face of low-grade fever). The CXR is important for ruling out other diagnoses because most CXR findings are nonspecific or rare. The rare CXR findings that occur with PE include the Westermark sign, Hampton hump, and Fleischner sign. The Westermark sign is an area of decreased pulmonary vascularity (oligemia) that causes a unilateral hyperlucency corresponding to the embolized arterial branch. Hampton hump is a wedge-shaped or rounded pleural-based infiltrate with the apex pointed toward the hilum and is frequently located adjacent to the diaphragm. Hampton hump is typically a late CXR finding associated with pulmonary infarction distal to the thrombus. Fleischner sign refers to a localized widening of an artery due to impaction of an embolus.

Electrocardiogram The ECG is abnormal in approximately 85% of individuals with PE. PE frequently causes sinus tachycardia and T-wave inversion in Leads V1 to V4. An S1-Q3-T3 electrocardiographic pattern is another common finding. This pattern includes an S wave in Lead I, a Q wave in Lead III, and an inverted T wave in Lead III. This finding is relatively specific, but insensitive.7 While ECG abnormalities may be suggestive of PE, the absence of such abnormalities has no significant predictive value.

Echocardiography Echocardiography can detect RV pressure overload and dysfunction caused by an acute PE. However, a negative result cannot exclude PE and signs of RV overload, or dysfunction may also be found in the absence of acute PE and due to concomitant cardiac or respiratory disease.8 The echocardiography is helpful when estimating the extent of PE in clinically severe cases. Suspected high-risk PE is an immediately lifethreatening situation, and patients presenting with shock or hypotension have a distinct clinical problem. In this situation, the probability of PE is high, and the differential diagnosis includes cardiac tamponade, acute coronary syndrome, acute valvular dysfunction, and aortic dissection. These patients may be so critical that only bedside diagnostic tests are possible. The most useful ­initial test, in this situation, is bedside transthoracic echocardiography (TTE). If PE is the cause of the patient’s hemodynamic decompensation, the TTE will demonstrate acute PH and RV dysfunction. A transesophageal echocardiogram may allow the direct visualization of thrombi in the PA, and its main branches and a bedside venous Doppler can detect a DVT.8

Pulmonary Embolism

Arterial Blood Gas Findings Patients with acute PE usually present with tachypnea and hyperventilation, causing arterial blood gases (ABGs) to commonly exhibit a low Paco2, with an elevated pH consistent with an acute respiratory alkalemia. The size of the vascular impairment determines the extent of the patient’s hypoxemia. In patients with suspected PE, a normal Pao2 does not rule out PE. ABG findings are not diagnostic of PE. However, profound hypoxemia without clear explanation is suspicious for possible PE.

Cardiac Biomarkers Elevated plasma troponin I or troponin T levels can occur in patients with PE secondary to RV dilation and collateral myocardial injury. Elevated troponin levels have a high risk of short-term mortality.10 PE needs to be considered in individuals presenting with chest pain or dyspnea and elevated plasma troponin levels. High concentrations of brain-type natriuretic peptides (BNPs) or the N-terminal of the prohormone of BNP (NT-proBNP) may be elevated during a PE that is

associated with RV overload. Elevated levels of BNPs are strongly associated with mortality in acute PE. Normal BNP levels are associated with a low mortality rate in PE.10

Treatment and Management The degree of hemodynamic compromise is the single most important predictor of in-hospital death in patients with massive PE. The PE-related mortality risk of these patients is >15%.8 Hemodynamic instability is a systolic BP 100 beats/ minute.21 Patients with low-risk PE may be candidates for early discharge or outpatient treatment. These patients are identified using the Hestia Decision Rule or the Simplified Pulmonary Embolism Severity Index (sPESI).22 The Hestia Decision Rule consists of 11 bedside criteria that all need to be negative for a patient to be considered for early discharge or outpatient treatment. The sPESI includes six criteria that must all be negative for the patient to be considered for early discharge or outpatient treatment. Table 17-5 shows both

TABLE 17-5 The sPESI and the Hestia Criteria sPESI Criteria

No

Yes

Hestia Criteria

Is the patient age >80 years?

Is the patient hemodynamically unstable?*

Does the patient have cardiopulmonary comorbidity?

Is thrombolysis or embolectomy necessary?

Does the patient have a history of cancer?

Does the patient have a high risk for bleeding?†

Is the Sao2 90% for more than 24 hours?

Is the systolic BP 15 mm Hg

PH due to left heart disease (Group 2) PH with unclear and/or multifactorial mechanisms (Group 5)

Isolated postcapillary PH (Ipc-PH)

DPG 3 WU

PH due to left heart disease (Group 2) PH with unclear and/or multifactorial mechanisms (Group 5)

Pulmonary Artery Hypertension

TABLE 17-7 Classification of PH Group Name

Subgroup

Etiology

1. PAH

1.1

Idiopathic PAH (IPAH)

1.2 1.2.1 1.2.2 1.2.3

Heritable PAH (HPAH) Bone morphogenetic protein receptor Type 2 (BMPR2) Other mutations Unknown

1.3

Drug and toxin induced

1.4 1.4.1 1.4.2 1.4.3 1.4.4 1.4.5

Associated with: Connective tissue disease Human immunodeficiency virus (HIV) infection Portal hypertension Congenital heart diseases Schistosomiasis

1’.1

Idiopathic

1’.2

Heritable

1’.3

Drug, toxin, and radiation induced

1’.4 1’.4.1 1’.4.2

Associated with: Connective tissue disease HIV infection

2.1

LV systolic dysfunction

2.2

LV diastolic dysfunction

2.3

Valvular disease

2.4

Congenital/acquired left heart inflow/outflow tract obstruction and congenital cardiomyopathies

2.5

Congenital/acquired pulmonary veins stenosis

3.1

COPD

3.2

Interstitial lung disease

3.3

Other pulmonary diseases with mixed restrictive and obstructive pattern

3.4

Sleep-disordered breathing

3.5

Alveolar hypoventilation disorders

3.6

Chronic exposure to high altitude

3.7

Developmental lung diseases

4.1

CTEPH

4.2 4.2.1 4.2.2 4.2.3 4.2.4 4.2.5

Other PA obstructions Angiosarcoma Other intravascular tumors Arteritis Congenital pulmonary arteries stenosis Parasites (hydatidosis)

1’. Pulmonary veno-occlusive disease and/or pulmonary capillary hemangiomatosis

1”. Persistent pulmonary hypertension of the newborn (PPHN) 2. PH due to left heart disease

3. PH due to lung diseases and/or hypoxia

4. CTEPH and other PA obstructions

(Continues)

479

480

CHAPTER 17  Pulmonary Vascular Diseases

TABLE 17-7 Classification of PH (Continued) Group Name

Subgroup

Etiology

5. PH with unclear and/or multifactorial mechanisms

5.1

Hematologic disorders: chronic hemolytic anemia, myeloproliferative disorders, splenectomy

5.2

Systemic disorders: sarcoidosis, pulmonary histiocytosis, lymphangioleiomyomatosis

5.3

Metabolic disorders: glycogen storage disease, Gaucher disease, thyroid disorders

5.4

Others: tumoral obstruction, fibrosing mediastinitis, chronic renal failure, segmental PH

specified by the World Symposium on PH are PAH (Group 1); PH due to left heart disease (Group 2); PH due to chronic lung disease and/or hypoxia (Group 3); chronic thromboembolic PH (CTEPH; Group 4); and PH due to unclear multifactorial mechanisms (Group 5).29 See Table 17-7. Each of the five categories or classification groupings of PH has a distinct mechanism responsible for the elevated PAP, a different natural history, and a different approach to treatment. Diagnosis, understanding, and the correct clinical application of the specific classifications of PH compels a sequence of investigative stages intended to establish a specific diagnosis, clarify clinical category and type of PH, and assess functional and hemodynamic impairment. A systematic approach typically begins with a clinical suspicion of PH followed by the employment of methods to detect PH, which ordinarily leads to the identification of an appropriate clinical classification. Proceeding with appropriate testing can potentially establish the specific type, functional capacity (FC), and hemodynamic status of persons with PH.

Clinical Signs and Symptoms The overall group of symptoms in patients with PH depends on the underlying disease; there are certain characteristic complaints attributed to PH. These characteristic complaints, however, are nonspecific and can lead to a delay in diagnosis. Initially, patients present with exertional dyspnea, lethargy, and fatigue. Because PH is progressive, the presentation evolves over time. Patients may eventually develop the signs and symptoms of severe PH with overt RV failure (e.g., exertional chest pain or syncope and congestion, including peripheral edema, ascites, and pleural effusion).30 Exertional chest pain may be difficult to distinguish from classical angina pectoris. In most circumstances, the chest pain is presumed to be related to the increased workload of the RV and RV ischemia, although in some cases an

enlarged PA can compress the left main coronary artery and produce true LV ischemia. When PH is severe, and the RV is failing, patients are unable to increase CO with exertion and may experience exertional light headedness or frank syncope. These are very poor prognostic signs.4 Uncommon symptoms include cough, hemoptysis, hoarseness, and wheezing. The hemoptysis is related to rupture of hypertrophied bronchial arteries.27 The hoarseness is due to Ortner syndrome, a compression of the left recurrent laryngeal nerve by a dilated main PA.30 Large airway compression can cause wheezing.27 Significant dilation of the PA may result in its rupture or dissection, leading to signs and symptoms of cardiac tamponade.27 Physical examination of the patient may reveal signs more related to the cardiac consequences of PH than to the actual disease of pulmonary vessels. PH does not cause any changes that can be noted on examination of the lungs, although patients with underlying lung disease often have findings related to their primary disease.4 There may be a left parasternal heave, due to RV enlargement. Patients frequently exhibit an accentuation of the pulmonic component of the second heart sound (P2) because of earlier and more forceful valve closure attributable to high pressure in the PA.4 Elevated jugular venous pressure, hepatomegaly, ascites, peripheral edema, and cool extremities characterize patients with advanced disease.27 Clinical examination may suggest an underlying cause of PH, such as COPD, interstitial lung disease, connective tissue disease, liver disease, and heart failure.

Etiology Several factors, occurring either individually or in combination, can affect the pulmonary circulation, resulting in an abnormal rise in PAP. The most common mechanism contributing to increased PAP (Table 17-6) is precapillary

Pulmonary Artery Hypertension Right lung

SVC

Capillary IVC

Left lung

Precapillary

Postcapillary

Capillary

RV

FIGURE 17-12  Pulmonary circulation showing areas affected by PH. See text for description.

PH. Precapillary PH develops through processes involving arterial destruction, obstruction, and constriction. Etiologies for this type of PH include PA hypertension, lung diseases, chronic thromboembolic disease, and multifactorial mechanisms. Postcapillary PH results in an increased pressure in the pulmonary vascular circuit distal to the capillaries and causes PAP elevation from left heart disease and multifactorial mechanisms. See Figure 17-12.

Epidemiology The true prevalence of PH in the general population is unknown, likely because of the broad classification and multiple etiologies. PH affects all age groups and racial populations as well as both genders.31 The age-standardized death rate in the United States ranges between 4.5 and 12.3 per 100,000 population.27 The mortality rates associated with PH for women are higher than those for men. One reason may be that women have a higher rate of connective tissue disease than men.32 The epidemiology of PH varies among the different etiologies of the five groups and even within each group. The group best studied is Group 1 PAH; idiopathic and heritable PAH is rare in the general population and estimated to be 5–15 cases per 1 million adults.33,34 PAH may occur in different settings depending on associated clinical conditions.29 The mean age at the time of diagnosis of PAH has increased from 36 years, in 1981, to between 50 and 65 years.27 In Group 2, PH due to left heart disease (PH-LHD), the prevalence of PH increases with the severity of the defect and the symptoms. PH occurs in virtually all patient with severe symptomatic mitral valve disease and in up to 65% of those with symptomatic aortic stenosis.35

The incidence of PH in Group 3 depends on the type and severity of the lung disease. Mild PH is common in both severe interstitial lung disease and severe COPD.36 Several studies suggest that 90% of those with severe COPD have mild-to-moderate PH and 3–5% have severe PH.37 The prevalence of PH due to interstitial lung disease is estimated to be between 8% and 32%, and the estimated prevalence of PH due to obstructive sleep apnea is 15–20%.31 The incidence of PH in Group 4, CTEPH, is unknown but estimated to be between 1% and 5% among survivors of acute PE.38 Within Group 5 (PH with unclear and/or multifactorial mechanisms), PH due to sickle cell has an incidence between 6% and 10%.39 PH is common in advanced sarcoidosis. Among sarcoidosis patients awaiting lung transplant, over 70% have significant PH.40

Pathology/Pathophysiology A normal PAPm at rest is ≤20 mm Hg; the definition of PH includes a PAPm of ≥25 mm Hg at rest. The hemodynamic variables that contribute to PAP can be explained using a variation of Ohm’s law, which is a fundamental law of physics. It states that the electric current flowing through a fixed linear resistance is directly proportional to the voltage applied across it and inversely proportional to the resistance.41 Hemodynamics are the physical factors that govern blood flow. In relating Ohm’s law to fluid flow, the voltage difference is the pressure difference (ΔP; sometimes called driving pressure, perfusion pressure, or pressure gradient), the resistance is the resistance to flow (R) caused by the blood vessels and their interactions with the moving blood, and the current is the blood flow (F). See Box 17-4. From the equation in Box 17-4, it is apparent that the PAPm is determined by the right-sided CO, PVR, and

481

482

CHAPTER 17  Pulmonary Vascular Diseases

BOX 17-4 Hemodynamic Variables of PH ΔP = F × R ΔP = PAPm − PVPm F=Q R = PVR

TABLE 17-8 Pulmonary Vascular Hemodynamic Abnormalities, Their Mechanisms, and Causative Medical Conditions Hemodynamic Variable

Mechanism

Medical Conditions

Occlusive vasculopathy of small pulmonary arteries and arterioles

• IPAH • Connective tissue disease • HIV infection • Congenital heart disease

Decreased area of pulmonary vascular bed

• Pulmonary emboli • Interstitial lung disease

Hypoxic vasoconstriction

• Hypoventilation syndromes • Parenchymal lung disease

Increased pulmonary vascular blood flow

Left-to-right shunt

• Atrial septal defects • Ventricular septal defects • Patent ductus arteriosus • Liver cirrhosis

Increased pulmonary venous pressure

Decreased forward blood movement

• Mitral valve disease • LV systolic or diastolic dysfunction • Constrictive pericarditis • Restrictive cardiomyopathy • Pulmonary venous obstruction

Increased PVR

Therefore, PAPm − PVPm = Q × PVR Then: PAPm = (Q × PVR) ÷ PVPm Key: ΔP = pressure gradient; F = blood flow; R = resistance; PAPm = mean pulmonary arterial pressure; PVPm = mean pulmonary venous pressure; Q = right-sided CO; and PVR = pulmonary vascular resistance.

mean pulmonary venous pressure.42 Increases in blood flow alone do not usually cause significant PH because the pulmonary vascular bed vasodilates and increases the number of vessels in response to increased flow. Increases in pulmonary venous pressure alone do not usually cause significant PH. However, a chronically increased flow and increased pulmonary venous pressure can increase PVR.42 Various medical conditions cause changes in PVR, blood flow, and pulmonary venous pressure. See Table 17-8. Regardless of the cause of the PH, a predictable sequence of events occurs. The RV hypertrophies and then dilates, causing the CO to fall. By the time the CO falls, the patient may have severe symptoms, including symptoms at rest.42 The five PH classifications have different pathophysiologic mechanisms, although each clinical presentation may be similar.

Group 1: Pulmonary Arterial Hypertension PAH was once regarded mainly as a disease of excess vasoconstriction, but this view was incomplete.43 PAH is a proliferative vasculopathy, characterized not just by vasoconstriction, but also by cell proliferation, fibrosis, and thrombosis. Hyperplasia and hypertrophy occur in the intima, media, and adventitia of the pulmonary arteries that are 50 mm Hg. §

Patients with a score of 4 may be at an increased perioperative risk from OSA; patients with a score of 5 or 6 may be at significantly increased perioperative risk from OSA. Practice Guidelines for the Perioperative Management of Patients with Obstructive Sleep Apnea. Anesthesiology. 2014;120(2):268-286. doi:10.1097/aln.0000000000000053.

enough time to complete the referral and study prior to the need for surgery. If the patient does not have a diagnosis of OSA but has a high risk of OSA, emergency surgery should be allowed. The decision to defer elective surgery for further evaluation is made on a case-by-case basis, based on the judgment that optimal management of OSA will improve patient outcome. When possible,

Recent findings of patients undergoing elective surgery from the Veterans Administration Surgical Quality Improvement Program demonstrated current smokers had a dose-dependent increase in postsurgical pulmonary complications (especially PP) based on pack-year exposure.28 A smoking history of ≥20 pack-years has an association with a fivefold increased risk of PPCs.17 Preoperative smoking is associated with an increased risk for general morbidity, wound complications, general infections, neurological complications, as well as pulmonary complications.12 Smokers produce more mucus and have slower mucus clearance, increased airway sensitivity, and increased pulmonary epithelial permeability and impaired macrophage and natural killer cytotoxic activity.1 Smoking cessation prior to elective surgery appears to improve several outcomes, such as wound healing and postoperative pulmonary recovery. One study showed that 2 months of preoperative smoking cessation is necessary for intraoperative sputum volume to decrease to the baseline levels of nonsmokers.15 A systematic review of 13 randomized controlled trials concluded that intensive smoking interventions initiated at least 4 weeks prior to surgery using multiple contacts for behavioral support and pharmacotherapy (Box 22-1) are beneficial for changing overall smoking behavior and reducing complications.29 Because there are no well-established guidelines for the duration of abstinence from smoking necessary to reduce

BOX 22-1 Strategies for Smoking Cessation31 Ask, advise, assess, assist, and arrange (steps to intervention for tobacco addiction) Behavioral counseling (to enhance motivation and abstinence) Pharmacotherapy Nicotine replacement therapy (NRT) ƒƒ Gum yy Lozenge yy Nasal spray yy Inhaler yy Sublingual tablet yy Transdermal patch yy Bupropion hydrochloride (sustained release) ƒƒ Varenicline tartrate ƒƒ

Preoperative Assessment for Pulmonary Risk pulmonary complications, more than 8 weeks may be preferable.30

Preoperative Assessment for Pulmonary Risk

Poor General Health (ASA Class >2)

It is possible to reliably identify patients at the highest risk for postoperative mortality and pulmonary complications with information that is available before the surgical procedure. A detailed history and physical examination are the most critical elements of preoperative risk assessment.7 The preoperative evaluation, particularly before major intrathoracic or upper abdominal surgery, needs to include any significant history of smoking and cough, obesity, and known underlying pulmonary and cardiac disease. Important factors in the preoperative assessment include the presence and character of a cough and sputum production; history or presence of abnormal breath sounds, including wheezing; and history and/or presence of shortness of breath and exercise intolerance. Other known medical conditions such as neurologic events capable of impairing normal airway protection mechanisms require consideration in the preoperative evaluation. While such occurrences may be subtle, obtaining a history of swallowing difficulties or prior aspiration may trigger perioperative intervention strategies likely to reduce the risk of aspiration. Relevant physical findings include the presence of wheezing or other adventitious lung sounds, prolonged expiration, or any other manifestations of pulmonary disease.

A patient’s overall health status is an essential determinant of pulmonary risk and the development of complications.2,7 Higher ASA physical status is associated with PPCs following both thoracic and non-thoracic surgery.32 An ASA classification of two or higher has an increased risk of PPCs when compared with an ASA classification of one.22 Refer back to Table 22-1. In a recent multicenter study involving seven U.S. academic centers, one-third of all patients with severe systemic disease (ASA physical status 3) undergoing non-cardiothoracic surgery for 2 hours or more had PPCs.4 Poor general health status, including impaired sensorium and functional dependency, also increases the risk of PPCs.22 Total dependency (the ability to perform any activity of daily living) more than doubles the patient’s likelihood of developing pneumonia.1

Congestive Heart Failure The risk of PPCs is high with patients who have CHF. Good-quality evidence shows that CHF is a significant risk factor for PPCs.15,23,33 Patients with preoperative CHF often have left atrial hypertension and pulmonary interstitial edema, which in turn resulted in a change in the pulmonary ventilation/blood flow ratio, thus causing postoperative hypoxemia and prolonged ventilation support.34 Preoperative CHF also causes the lymph to back up, leading to pulmonary alveolar edema and decreasing pulmonary compliance, thus further aggravating respiratory dysfunction. Therefore, patients with preoperative CHF are prone to PPCs.34

KNOWLEDGE CHECK QUESTIONS 1. True or False: According to the ASA' Physical Status Classification System, a patient with a severe systemic disease that is not life threatening is in category ASA-2. 2. True or False: COPD is a modifiable risk factor for PPCs. 3. True or False: A fivefold increased risk of PPCs is present with a smoking history of ≥20 pack-years. 4. True or False: CHF is a significant risk factor for PPCs.

Pulmonary Function Testing The routine preoperative evaluation of pulmonary function testing (spirometry) is less useful in predicting postoperative pulmonary complication risk than a thorough clinical assessment including the history and physical examination and determination of functional status (ASA classification).23 Spirometry is, however, appropriate for individuals suspected of having a significant underlying cardiopulmonary disease by history and/or physical examination.23 See Box 22-2.

BOX 22-2 Criteria for Preoperative Pulmonary Function Testing7 Assess current COPD or asthma control to idenƒƒ

tify the need for optimizing therapy Differential diagnosis for unexplained pulmonary ƒƒ issues after history and physical exam Not to be used as the primary factor to deny ƒƒ surgery Not to be used routinely prior to abdominal surƒƒ gery or for other high-risk operations (except for lung resection surgery)

597

598

CHAPTER 22  Postoperative Pulmonary Complications

Chest Radiography Preoperative chest radiographs add little to the clinical evaluation in identifying healthy patients at risk for perioperative complications.7 A systematic review of the literature by Smetana, Lawrence, and Cornell concluded that clinicians might predict most abnormal preoperative chest radiographs based on the history and physical examination and that chest radiography only rarely provides unexpected information that influences preoperative management.15 It is reasonable, however, to obtain a preoperative chest radiograph in patients with known cardiopulmonary disease and in those over age 50 years who are undergoing surgical procedures, including upper abdominal, aortic, esophageal, and thoracic surgery. Chest radiography is especially useful when PPCs are clinically suspected as with the development of unexplained fever, unexpected significant hypoxemia, change in normal respiratory effort (development of tachypnea), alterations in breath sounds on lung auscultation, or change in the peripheral white blood cell count. A detailed review of the postoperative chest radiography may substantiate the presence of an infiltrate, signs of lung volume loss as with atelectasis or lung collapse, or the development of pleural effusion (PE) or pneumothorax. Other radiography findings include an increased density around atelectasis, the presence of air bronchograms, hemidiaphragm elevation on the affected side of atelectasis, and mediastinal shift with the significant collapse of lung tissue on the affected side.

Assessment of Oxygenation Measurement of oxygenation via pulse oximetry is an essential factor in the prediction of PPCs. Pulse oxygen saturation (Spo2) assessment is included in the ARISCAT Risk Index3 and is helpful for stratifying risk, particularly prior to high-risk surgeries. Current data do not support the use of preoperative arterial blood gas analyses to stratify risk for PPCs.7

Risk Prediction Tools Risk prediction tools use preoperative factors to estimate the risk of PPCs. These tools are for the stratification of risk when advising patients prior to surgery and, in some cases, to identify patients most likely to benefit from risk-reduction interventions. For example, patients predicted to be at high risk for PPCs may be scheduled for postoperative care in a more intensive care location.7 There are four indices available for PPC risk stratification. These include the Gupta calculator for postoperative respiratory failure, the Gupta calculator for postoperative pneumonia, the Arozullah Respiratory Failure Index, and the ARISCAT Risk Index. These tools are a useful starting point when estimating pulmonary risk before major noncardiac surgery, and they guide conversations between the surgeon and the patient.7

The Gupta calculator for postoperative respiratory failure utilizes numerous preoperative factors to predict the risk of failure to liberate a patient from mechanical ventilation within 48 hours of surgery or unplanned intubation within 30 days of surgery.35 The Gupta calculator was developed to aid in the surgical decision making and informed consent process. It is in the form of an interactive spreadsheet and is available online as a free download.35 The Gupta calculator for postoperative pneumonia is also available online for downloading. The Arozullah Respiratory Failure Risk Index is a validated model for identifying patients at risk for developing postoperative respiratory failure and may be useful for guiding perioperative respiratory care.36 This risk index is based on several factors, including laboratory results, type of surgery, history of COPD, age, and functional status. The index is too complicated for clinical practice and may be of value in research settings.7 The ARISCAT Risk Index is based on seven easily assessed factors. These factors include age, preoperative Spo2, respiratory infection within the last month before surgery, preoperative anemia, surgical incision site, duration of operation, and whether the surgery is emergent.3 Each factor is assigned a risk score that is weighted. The higher the risk, the higher the weight, based on the statistical findings of the research.3 The ARISCAT Risk Index is useful for differentiating three levels of PPC risk.

KNOWLEDGE CHECK QUESTIONS 1. True or False: Spirometry is performed only preoperatively on select patients who are suspected of having pulmonary disease. 2. True or False: Poor preoperative pulmonary function test results can cause a patient to be denied surgery. 3. True or False: Two indices are available for postoperative pulmonary complication risk strategy.

Common PPCs The term PPC encompasses almost any complications that affect the lungs after anesthesia and surgery. These complications can have significant adverse effects on postoperative patients and are difficult to predict, even with prediction tools. Table 22-4 shows six common PPCs and their definitions. While these PPCs represent some of the common causes of overall perioperative morbidity and mortality in the patient undergoing surgery, other adverse events include acute upper airway obstruction, exacerbation of OSA, pulmonary edema, pulmonary embolism, abdominal compartment syndrome, and tracheal laceration or rupture.3

Common PPCs

TABLE 22-4 Common PPCs and Definitions1,3,37,38 Complication

Definition

Atelectasis

Lung opacification with a shift of the mediastinum, hilum, or hemidiaphragm toward the affected area and compensatory over-inflation in the adjacent non-atelectatic lung

Bronchospasm

Newly detected expiratory wheezing treated with bronchodilators

Chemical pneumonitis (aspiration)

Acute lung injury after the inhalation of regurgitated gastric contents

Pleural effusion

Chest radiograph showing blunting of the costophrenic angle, loss of sharp silhouette of the ipsilateral hemidiaphragm in an upright position, evidence of displacement of adjacent anatomical structures, or (in supine position) a hazy opacity in one hemithorax with preserved vascular shadows

Pneumothorax

Air in the pleural space with no vascular bed surrounding the visceral pleura

Respiratory failure

Failure to wean from mechanical ventilation within 48 hours after surgery or unplanned intubation/reintubation intraoperatively or postoperatively

Respiratory infection (pneumonia)

Treatment with antibiotics for a suspected respiratory infection with one of the following criteria: new or changed sputum, new or altered lung opacities, fever, leukocyte count >12,000/mm3

Anesthetic gas effects can also produce adverse effects that may lead to pulmonary complications, including a reduction in diaphragmatic function, impairment of mucociliary clearance for several days, and elimination of protective cough, and may inhibit hypoxic vasoconstriction in poorly ventilated areas of the lung. These mechanisms can foster consequences of atelectasis, reduction in FRC, and ventilation–perfusion mismatch.39

Atelectasis As soon as the patient loses consciousness from general anesthesia, adverse respiratory effects begin. The anesthesia depresses the patient’s central respiratory drive, causing prolonged apnea. Because the central nervous system (CNS) is affected, ventilatory responses to hypercapnia and hypoxemia are blunted. Although artificial ventilation maintains carbon dioxide removal and oxygenation, the cephalad diaphragm is displaced in the dependent areas, and there is a reduction in the crosssectional area of the chest wall.37 These changes in endexpiratory muscle tone lead to a decrease in FRC when compared with the patient’s awake, supine volume.37 See Figure 22-1.

While often clinically uneventful, atelectasis is one of the most common PPC, particularly following abdominal and thoracoabdominal procedures.3 It is estimated that up to 15–20%37,40 of the lung is regularly collapsed at its base during uncomplicated anesthesia prior to any surgery and can persist for several days following surgery.3 See Figure 22-2. Anesthesia-induced lung collapse commonly occurs with almost all anesthetics mainly from hyperoxygenation during induction,40 anesthesia-related loss of muscle tone,37 and reduction in FRC40 resulting in absorption atelectasis behind closed airways. Other potential causes of atelectasis include lung tissue compression as well as the loss of surfactant or surfactant function. The administration of 100% oxygen following a vital capacity maneuver in lung tissue previously collapsed and subsequently attempted to be re-expanded will frequently result in rapid recurrence of atelectasis. This also occurs with the combination of oxygenation and airway suctioning. Given the likelihood of anesthetic agents and increased oxygen in contributing to the development of postoperative atelectasis, it has become common to utilize alveolar recruitment maneuvers prior to extubation followed by ventilation with moderate concentrations of Fio2.1,41 The underlying mechanisms responsible for the development of lung atelectasis include increases in bronchial secretion volume, increases in secretion viscosity, reduced tidal volume, as well as FRC and the inability to effectively cough.3 Atelectasis resulting in the loss of functional alveolar units is recognized as a significant pathophysiologic mechanism responsible for postoperative hypoxemia. The formation of atelectasis in high-risk patients may be prevented during invasive mechanical ventilation by the application of positive end-expiratory pressure (PEEP). Following extubation, however, this positive airway pressure is lost, and subsequent collapse of alveoli can occur immediately. When this effect occurs in combination with suboptimal postoperative coughing, lack of deep inspirations, PEs, and increased interstitial lung water, the formation of atelectasis can progress further, reducing oxygenation. CPAP can be continued in the spontaneously breathing patient following extubation from mechanical ventilation. CPAP is used either intermittently or continuously with patients who are unable to perform effort-dependent measures, which increase postoperative lung volumes.30 Treatment with CPAP, theoretically, prevents further collapse of alveolar units, while it simultaneously acts to increase FRC and arterial oxygenation. CPAP also effectively reduces respiratory workload as well as cardiac preload. The clinical presentation of postoperative atelectasis can range from subclinical or asymptomatic to manifesting overt clinical signs of increased work of breathing (respiratory distress) and hypoxemia.3 Significant postoperative atelectasis is usually accompanied

599

600

CHAPTER 22  Postoperative Pulmonary Complications

Expiration TLC

Inspiratory muscles

Lung volume Expiratory muscles

RV Inspiration

Awake (coordinated) Expiration

Anesthetized (incoordinated) Expiration

Lung volume Inspiration

Lung volume Inspiration

FIGURE 22-1  Model showing how incoordination of respiratory muscles impairs lung function. The position of the midpoint of a horizontal bar,

suspended between fixed surfaces by inspiratory and expiratory muscles, represents lung volume as denoted on a scale from low (residual volume, RV) to high (total lung capacity, TLC) volumes. During awake, coordinated inspiration (lower left), the bar remains horizontal (representing normal chest wall expansion), and lung volume changes efficiently. When anesthetized, muscle activity becomes uncoordinated, such that the bar tilts during inspiration (representing chest wall distortion), impairing lung expansion. Incoordination continues into the postoperative period after thoracic and abdominal surgery. Dashed lines in lower panels denote the end-expiratory position of the bar. Reproduced with permission from Warner D. Preventing postoperative pulmonary complications. Anesthesiology. 2000;92(5):1467–1472 (Figure 1, p. 1468). doi:10.1097/00000542 -200005000-00037.

by tachycardia, associated shallow and rapid breathing, increased late inspiratory crackles, or reduced breath sounds on chest auscultation accompanied by dullness on chest percussion over the area of sizeable collapse.3 A fever can occur concurrently with the presence of an underlying infection. Chest radiography can substantiate the existence of consolidation and parenchymal collapse. The onset of hypoxemia due to postoperative atelectasis tends to occur within the first 48 hours following most major surgeries (such as early after the patient has left the post-anesthesia care unit). Generally, hypoxemia becomes most severe during the second postoperative night and continues through the fourth or fifth postoperative night.3 Hypoxemia that develops earlier perioperatively as in a patient who has not yet been discharged from the post-anesthesia care unit should prompt investigation into alternate postoperative complications such as hypoventilation due to residual anesthetic effects and upper airway obstruction due to airway tissue edema. The upper airway obstruction can result from

the accumulation of pharyngeal secretions, prolapse of the tongue posteriorly, or either iatrogenic or allergic tongue edema. Early ambulation and the use of breathing exercises and expiratory maneuvers, such as positive expiratory pressure, are especially crucial following upper abdominal surgery in preventing atelectasis.42,43

Bronchospasm Exacerbations of bronchospasm in the postoperative period can be caused by reflex constriction of bronchial smooth muscles due to tracheal stimulation by secretions, suctioning, endotracheal intubation, or other surgical stimulation. Additionally, postoperative bronchospasm can be triggered by aspiration, histamine release caused by certain medications such as opiates, tubocurarine, or atracurium, an allergic response to medications, or an exacerbation of a chronic pulmonary condition, such as asthma or COPD.3 The clinical manifestations of postoperative bronchospasm are identical to those of asthma or COPD.

Common PPCs

Surgical trauma

Somatic nerve

Reflex inhibition

Vagus nerve

Muscle disruption –

Pain

Phrenic nerve

Chest wall

Diaphragm Abdominal viscera – –

Hypoventilation atelectasis

FIGURE 22-2  Factors producing respiratory muscle dysfunction after surgical trauma. From left to right: (1) surgical trauma stimulates CNS

reflexes mediated by both visceral and somatic nerves that produce reflex inhibition of the phrenic and other nerves innervating respiratory muscle; (2) mechanical disruption of respiratory muscles impairs efficiency; and (3) pain produces voluntary limitation of respiratory motion. These factors all tend to reduce lung volumes and can produce hypoventilation and atelectasis. Reproduced with permission from Warner D. Preventing postoperative pulmonary complications. Anesthesiology. 2000;92(5):1467–1472 (Figure 2, p. 1469). doi:10.1097/00000542 -200005000-00037.

These manifestations include wheezing, chest tightness, tachypnea, prolonged expiratory time, dyspnea, small tidal volumes, and hypercapnia. Treatment includes the removal of the cause, if it is medication, and bronchodilator administration. The decision to use an inhaled beta-2-agonist alone or in combination with a short-acting muscarinic antagonist, ipratropium bromide, is made on a case-by-case basis, depending on the severity of the bronchospasm.3

Chemical Pneumonitis Surgical patients are at risk for chemical pneumonitis resulting from the aspiration of acidic gastric contents

during the perioperative period. Anesthetic agents depress the airway protective reflexes, which predispose patients to aspiration.44 The increased risk for aspiration and chemical pneumonitis during the perioperative period is most likely to be related to the anesthetic-induced depression of airway protective reflexes and the use of muscle relaxants and pain medications.3 The incidence of aspiration is infrequent in healthy adults; it is more common in obstetric and pediatric patients.3 Most aspirations occur during tracheal extubation or laryngoscopy. A high ASA classification and emergency surgery are associated with a higher risk of aspiration.3

601

602

CHAPTER 22  Postoperative Pulmonary Complications Witnessed aspiration is treated with lateral head positioning and suctioning of the oropharynx. Patients with uncertain aspiration may development coughing, diffuse crackles on lung auscultation, abrupt onset of dyspnea, tachycardia, fever, bronchospasm, hypoxemia, and frothy pink sputum.3,44 Patients who do not develop these signs and symptoms are unlikely to develop chemical pneumonitis.3 However, some patients may develop a secondary bacterial infection (pneumonia) or acute respiratory distress syndrome (ARDS).3

Pleural Effusion Pleural effusion (PE) occurs because of the deterioration of the balance of absorption and secretion in the pleura. It occurs most often within the first week following cardiac45 and upper abdominal surgeries.3 A PE is more common following abdominal surgery (especially upper abdominal surgery), among patients with postoperative atelectasis, and among patients with free abdominal fluid. A postoperative patient with a significant amount of pleural fluid, particularly when associated with fever, needs a diagnostic thoracentesis to rule out pleural infection as a cause. If an effusion develops more than 72 hours after surgery, it is probably not related to the surgical procedure itself and alternative explanations require investigation, including conditions such as pulmonary embolization, intra-abdominal infection, and cardiac decompensation due to volume overload. Most postoperative PEs resolve spontaneously within a few days and, therefore, do not require intervention. However, atypical characteristics of either the PE or the patient’s clinical course warrant diagnostic evaluation of the effusion. Postoperative PEs are evaluated in the same way as other PEs.3

Pneumothorax Tension pneumothorax is suspected in patients with chest pain, dyspnea, tachypnea, hypoxemia, hypotension, distended neck veins, tracheal deviation, or risk factors that include attempted or actual central line insertion, surgery in the neck or thorax, or chronic lung disease. A needle decompression can be performed immediately, followed by chest tube placement as soon as possible if the thoracotomy equipment is not immediately available.44

Respiratory Failure Postoperative respiratory failure accounts for more than 20% of all patients receiving ventilatory support3 and is one of the most serious pulmonary complications.38 Prolonged mechanical ventilation is frequently a cause for delayed recovery following cardiac surgery.46 Respiratory failure requiring unplanned reintubation in the

postoperative period is associated with high morbidity, leading to a longer hospital stay, and increase in 30-day mortality to as high as 18-fold.47–49 Older individuals have a higher incidence of unanticipated reintubation within the first 72 hours after surgery.47,48 The first 6 hours post extubation have the highest risk of reintubation due to pulmonary edema, atelectasis, pneumonia, aspiration, impaired brain function, and airway obstruction.3 Postoperative respiratory failure can be caused by several factors. The loss of airway protection results from a variety of risk factors, including neurologic impairment, absent or ineffective cough, absent gag reflex, or laryngeal edema. Failure to oxygenate leading to hypoxemic respiratory failure (Type I respiratory failure) is another cause. Also, a failure to ventilate leads to hypercapnic respiratory failure (Type II respiratory failure). Postoperative respiratory failure is considered by many to be an extremely morbid event and marker of ill health that reliably forecasts additional postsurgical complications. Fortunately, the occurrence of respiratory failure is uncommon in postoperative patients without preexisting cardiopulmonary disease, such as severe COPD or the presence of a neuromuscular disorder subjected to thoracic or upper abdominal surgery. Acute respiratory failure may, however, occur in patients without preexisting cardiopulmonary or neuromuscular disorders if circumstances of overwhelming pneumonia, PE, pneumothorax, or acute airway obstruction occur during the postoperative period. One study found postoperative patients who developed respiratory failure as a complication of surgery had a 26% mortality within 30 days of their surgery. In this study, 6% had a myocardial infarction, 35% developed pneumonia, 10% developed acute renal failure, and 3% developed deep vein thrombosis (DVT) or pulmonary embolism.50 Incidence rates of these events were lower than 2% among patients ­without respiratory failure.50 ARDS is recognized as a leading cause of postoperative respiratory failure, associated with a mortality rate approaching 40% in the general population and 80% in the subset of patients undergoing cardiac surgery.51 This represents a significant concern with profound economic implications.

Respiratory Infection Postoperative pneumonia (PP), the third most common PPC, is a major cause of morbidity and high cost of care in the postsurgical patient.52,53 A diagnosis of PP is clinically made in a patient who develops fever, increased secretions, purulent sputum, leukocytosis, and hypoxemia that is associated with a new or progressive infiltrate on chest x-ray. PP tends to occur within 5 postoperative

Common PPCs days.3,40 The incidence of PP ranges from a rate of 3.0% to greater than 20% in high-risk groups, depending on the patient population and the diagnostic criteria utilized.5 The incidence of PP abruptly increases among patients who undergo prolonged tracheal intubation for ≥48 hours.5 Risk factors for PP after non-cardiothoracic surgery include smoking, age >70 years, ASA >2, preexisting COPD, and high-risk surgeries.40 The occurrence of PP is consistently associated with increased ICU and hospital LOSs. PP is associated with a higher postoperative mortality rate in all risk groups depending on the severity of illness, comorbid disorders, and causative pathogens.5 PP, especially ventilator-associated pneumonia, is a result of the aspiration of microorganisms from the subglottic area.40 See Table 22-5. Another cause of PP is the aspiration of regurgitated material from the digestive tract. PP is frequently caused by resistant organisms.3 Factors contributing to the development of PP following aspiration include the predominant organism(s), a large inoculum, and compromised host defenses.5 Although aspiration that leads to pneumonia can occur at various times in the perioperative period, most aspirations occur during tracheal intubation. Bronchial airway contamination following intubation occurs from bacterial migration within or surrounding

Cuff Biofilm

(A)

Cuff Microaspiration

(B) TABLE 22-5 Microorganisms That Cause PP3,5 Microorganism

Risk Factors

Haemophilus influenza Streptococcus pneumoniae

Traumatically injured patients are at higher risk, predominate in early infections

Methicillin-resistant Staphylococcus aureus (MSRA)

Previous antibiotic use, a positive nasal screen for MSRA, long operations (>5 hours) and emergency surgery, predominates in late infections

Staphylococcus aureus

Mechanically ventilated neurosurgical patients, victims of blunt trauma and coma, and patients with closed head injuries

Pseudomonas aeruginosa

Intubation >8 days, structural lung disease (e.g., bronchiectasis, cystic fibrosis, and COPD), corticosteroid therapy, malnutrition, and prolonged exposure to antibiotics, predominates in late infections

Acinetobacter species

Mechanical ventilation, predominates in late infections

Anaerobic species

Abdominal surgery

FIGURE 22-3  (A) Biofilm on the inner wall of the endotracheal

tube with distal migration of microorganisms through the lumen. (B) Microaspiration with distal migration of microorganisms around the inflated endotracheal tube cuff. Reproduced with permission from Shander A, Fleisher LA, Barie BS, et al. Clinical and economic burden of postoperative pulmonary complications: Patient safety summit on definition, risk-reducing interventions, and preventive strategies. Crit Care Med. 2011; 39(9):2166 (Figure 1).

the endotracheal tube. Bacterial movement through the endotracheal tube can form a biofilm, which represents an aggregate of colonizing, adherent microorganisms that may exist on the inner surface of the tube as early as 6 hours after tracheal intubation.5 When present, this collection of organic material eventually descends by gravity into the distal airways. Microaspiration from oropharyngeal secretions permits bacterial movement from around an endotracheal tube cuff because of improper cuff position or inflation, cuff deflation, tube manipulation, or patient movement. Secretions can also leak through channeled folds that develop despite a properly positioned and inflated high-volume, lowpressure cuff.5 See Figure 22-3. Some endotracheal tubes have integrated subglottic suctioning ports to provide continuous suctioning of accumulated secretions around the cuff of the endotracheal tube. See Figure 22-4

603

604

CHAPTER 22  Postoperative Pulmonary Complications

FIGURE 22-4  Endotracheal tube with subglottic suction.

KNOWLEDGE CHECK QUESTIONS 1. True or False: Anesthetic gas can impair mucociliary clearance for several days. 2. True or False: Increasing the tidal volume during surgery helps in in reducing the development of atelectasis. 3. True or False: Hypoxemia due to postoperative atelectasis occurs within the first 48 hours following most major surgeries. 4. True or False: The greatest risk for postoperative chemical pneumonitis occurs with patients who have a low ASA classification.

Strategies to Reduce PPCs Perioperative risk-modification strategies to reduce preventable patient and procedure surgery-related pulmonary complications should be routinely implemented, especially in higher-risk patients. Despite a robust enthusiasm to curb the adverse effects that can result from invasive surgery, a systematic review of strategies to reduce PPCs following surgery has identified very few evidence-based interventions that definitively impact reduction of these complications. Individuals presenting with symptoms of a cough or shortness of breath

preoperatively need assessment to determine the underlying etiology of these symptoms and to stratify the risk for PPCs. Concurrent medical disorders need treatment when identified because chronic medical comorbidities are notably essential determinants of perioperative morbidity and mortality.

Preoperative Strategies Treatment to decrease the risk of PPCs starts before surgery. These strategies include, but are not limited to, patient education, smoking cessation, preoperative exercises, pulmonary rehabilitation, and presurgical weight loss.

Patient Education Preoperative education is vital in preparing the patients for what is expected as well as what they could potentially encounter following surgery. Information about the type of surgery planned, the degree of postoperative pain intensity for the specific operation, the possibility of PPCs after surgery, and the types of respiratory interventions used during the postoperative period is essential to this education. The best time to teach lung expansion maneuvers, such as coughing, IS, and voluntary deep breaths and inspiratory muscle training is ­before surgery. It is challenging to explain these strategies to patients with surgical pain. A systematic review of cardiac patients showed that preoperative

Strategies to Reduce PPCs intervention intending to improve the patient’s ability to cope with the surgery reduced PPCs.54

Smoking Cessation Cigarette smoking is a known health risk, and current smokers have an increased risk for PPCs. The preoperative evaluation provides an opportunity to discuss the benefits of smoking cessation with the patient.55 However, one concern about smoking cessation in the immediate preoperative period is that abrupt removal of the irritant effect of cigarette smoke can inhibit coughing and lead to retention of secretions and small airway obstruction. It takes several weeks for the improvement in ciliary action, small airway function, and decreased mucus production to occur.56 An important clinical question is whether quitting smoking less than 8 weeks prior to surgery could, in fact, increase PPCs. Systemic reviews and meta-analyses, however, have not supported that concern.30 A large retrospective cohort analysis of elective operations from 2002 to 2008 yielded 393,794 patients in the Veterans Affairs Surgical Quality Improvement Program for all surgical specialties and found that there is a dose-dependent increase in PPCs based on pack-year exposure. Those with more than 20 pack-years of cigarette smoking had significant increases in smoking-related surgical complications, including PPs and deaths.57 A literature review of 25 studies comparing current smokers and the risk of respiratory complications found that at least 4 weeks of abstinence from smoking reduces respiratory complications. Short-term (20/100,000)

Not demonstrated

Residents and employees of high risk congregate settings

Yes

None

Not demonstrated

LTBI testing strategy Likely to be infected Low to intermediate risk of progression (TST ≥ 10 mM)

Likely to be infected High risk of progression (TST ≥ 5 mM)

Unlikely to be infected (TST > 15 mM) Risk of developing tuberculosis if infected Low No risk factors

Intermediate (RR 1.3–3)

High (RR 3–10)

Clinical predisposition Diabetes Chronic renal failure Intravenous drug use

Children age less than 5 HIV infection Immunosuppressive therapy Abnormal CXR consistent with prior TB Silicosis

Benefit of therapy Not demonstrated

Yes

FIGURE 23-5  Evaluation of individuals with LTBI based on the risk of infection, the risk of progression to TB, and benefit of therapy. The three

groups are unlikely to be infected, likely to be infected with low-to-intermediate risk of progression, and likely to be infected with a high risk of progression. CXR, chest radiography; RR, respiratory rate. Reproduced with permission from Lewinsohn D, Leonard M, LoBue P, et al. Official American Thoracic Society/Infectious Diseases Society of America/Centers for Disease Control and Prevention Clinical Practice Guidelines: Diagnosis of Tuberculosis in Adults and Children. Clin Infect Dis. 2017;64(2):111–115 (Figure 1, p. 113). doi:10.1093/cid/ciw778.

blood to be drawn for testing. The results can be available in 24 hours, and the laboratory test is not open to the subjectivity, as is the TST. Two IGRAs are available and approved by the U.S. Food and Drug Administration (FDA) for the diagnosis of TB infection. They are QuantiFERON®-TB Gold In-Tube test (QFT-GIT) and T-Spot®.TB test. IGRAs identify the presence of M. tuberculosis infection by measuring the immune response to the TB proteins in whole blood. IGRAs cannot differentiate between LTBI and active TB disease. As with the TST, additional tests are needed to diagnose or rule out TB disease.1 A positive IGRA means that the person is infected with TB bacteria. A negative IGRA means that the individual’s blood did not react to the test and that LTBI or TB disease is not likely. IGRAs are the preferred method of TB infection testing for people who have received bacille Calmette–Guérin (BCG is a vaccine for TB) and people who have a difficult time returning for a second appointment to look for a reaction to the TST. There is no problem with repeated IGRAs.8,22

The BCG vaccine is a live, attenuated (weakened) vaccine derived from a strain of M. bovis. The BCG vaccination is not recommended in the United States due to a combination of factors. These factors include the low risk of infection with M. tuberculosis, the variable efficacy of the BCG vaccine against pulmonary TB, the small risk of severe disseminated TB disease in young children in the United States, and the vaccine’s interference with the ability to determine TST reactivity. Many highly TB-prevalent countries vaccinate infants with BCG as part of their TB control effort to prevent children from contracting severe disseminated TB or TB meningitis.8 The TST or IGRA is not contraindicated for persons who have been vaccinated with BCG. The TST or IGRA results are used to support decisions about the diagnosis of infection with M. tuberculosis. TST in persons vaccinated with BCG should be interpreted using the same criteria for those not BCG vaccinated. The booster phenomenon may occur among persons who have had a prior BCG vaccination.

621

622

CHAPTER 23  Pulmonary Tuberculosis The booster phenomenon occurs mainly in previously infected, older adults whose ability to react to tuberculin has waned over time. When these people are skin tested many years after infection with M. tuberculosis, they may have an initial negative reaction. However, if they are tested again within a year of the first test, they may have a positive result. This is because the first TST “triggered the memory” of the immune system, boosting its ability to react to the second TST. It may appear that these people were infected between the first and second tests (recent TB infection). The second, positive test reaction is a boosted reaction due to TB infection that occurred a long time ago. These people may still be considered for LTBI treatment if they fit into a high-risk category for progression to TB disease. While both TST and IGRA testing provide evidence for infection with M. tuberculosis, they cannot distinguish active from latent TB. Therefore, the diagnosis of active TB must be excluded before embarking on treatment for LTBI. This is typically done by determining whether symptoms suggestive of TB disease are present, performing a chest radiograph, and, if radiographic signs of active TB disease are seen, then sputum sampling is performed and the patient managed accordingly.23

Testing for TB Disease The key to the diagnosis of TB is a high index of suspicion. Diagnosis is not difficult with a high-risk patient with typical symptoms and a classic chest radiograph. On the other hand, the diagnosis can be easily missed in an elderly patient or a teenager with a focal infiltrate. The initial suspicion of pulmonary TB is often based on

FIGURE 23-6  Chest radiograph, PA view, of a 60-year-old female

an abnormal chest x-ray in a patient with symptoms, although computed tomographic (CT) scanning is more sensitive than plain chest radiography for diagnosis, particularly for smaller lesions located in the apex of the lung.8

Radiographic Procedures Some patterns of chest radiographic abnormalities are considered more “typical” of TB disease.22 These “classic” patterns include upper lobe infiltrates and cavitary lesions. See Figure 23-6. However, virtually any radiographic pattern—from a normal film or a solitary pulmonary nodule to diffuse alveolar infiltrates in a patient with adult respiratory distress syndrome—may be seen.8 Old, healed TB presents a different radiologic appearance from active TB. Dense pulmonary nodules, with or without visible calcification, may be found in the hilar area or upper lobes. Smaller nodules, with or without fibrotic scars, are often seen in the upper lobes, and upper lobe volume loss often accompanies these scars.2 In patients with HIV infection, the nature of the radiographic findings depends, to an extent, on the degree of immunocompromise produced by the HIV infection. The more advanced the HIV disease, the more “atypical” the chest x-ray. Cavitation is uncommon in the case of advanced HIV, and lower lung zone or diffuse infiltrates and intrathoracic adenopathy are frequent.2 See Figure 23-7. Thus, while certain chest x-ray findings can be indicative of TB, it remains an insensitive and nonspecific test.22 CT may be useful in interpreting questionable ­findings on plain chest radiography and may be helpful in diagnosing some forms of extrapulmonary TB. 

patient diagnosed with pulmonary TB, showing fibro-exudative infiltrates at the right apex and left middle lung zone.

FIGURE 23-7  Chest radiograph, PA view, of a 43-year-old male with

© Santibhavank P/Shutterstock.

© Suttha Burawonk/Shutterstock.

HIV disease and TB disease.

Diagnostic Testing Magnetic resonance imaging is useful in the diagnosis of intracranial TB.8

Bacteriologic Examination A critical component for the diagnosis of TB disease is the bacteriological examination. The TB bacteriological examinations are done in a laboratory and identify M. tuberculosis, as well as other mycobacteria. There are five components to the bacteriologic examination: specimen collection, AFB smears, nucleic acid amplification, specimen culturing and identification, and drug susceptibility testing. For diagnostic purposes, all persons suspected of having TB disease need to have sputum specimens collected for an AFB smear and culture, even those without respiratory symptoms. A minimum of three consecutive sputum specimens is required. Each of these specimens is collected in 8- to 24-hour intervals, with at least one being an early morning specimen.1 Methods for obtaining a sputum specimen include a spontaneous sputum sample, sputum induction, bronchoscopy, and gastric washing. See Table 23-6. Smear examination is a quick procedure, the results of which are usually available within 24 hours of specimen collection. If AFB is found on a sputum smear, it is considered smear positive,

and it often indicates TB disease. However, a positive smear does not confirm a diagnosis of TB because some stained mycobacteria are not M. tuberculosis. Additionally, smear-negative results do not exclude TB disease, because the AFB may not be seen. Rapid identification of a microorganism is done via direct detection using nucleic acid amplification (NAA). NAA tests amplify DNA and RNA segments of the mycobacterium. This testing permits the identification of M. tuberculosis in as little as several hours, with high specificity and sensitivity approaching that of culture.1,8 It is recommended that the NAA testing be performed on at least one respiratory specimen from each patient with signs and symptoms of pulmonary TB for whom a diagnosis of TB is being considered but has not yet been established, and for whom the test result would alter case management or TB control activities, such as contact investigations.1,23 The gold standard for the definitive diagnosis of TB disease is the isolation and identification of M. tuberculosis in cultures from a clinical specimen.1,8,23 Culture examinations should be done on all diagnostic specimens, regardless of AFB smear or NAA results. Liquid and solid mycobacterial cultures are available, but at least the liquid culture needs to be done on all specimens.23 Because most species of mycobacteria

TABLE 23-6 Methods of Obtaining a Sputum Specimen Method

Description

Advantage

Disadvantage

Spontaneous sputum sample

• Patient coughs up sputum into a sterile container

• Inexpensive • Easy to do

• Patient may not be able to cough up sputum or cough up saliva instead of sputum • Coaching and supervision by a healthcare provider is necessary

Sputum induction

• Patient inhales aerosolized, hypertonic saline (between 3% and 10%) • Used when spontaneous coughing is nonproductive of sputum

• Easy to do

• Requires special equipment • May cause bronchospasm • Specimens may be watery and may be confused with saliva (label “induced specimen”)

Bronchoscopy

• Bronchoscope is passed through the mouth or nose directly into the diseased portion of the lung, and sputum or lung tissue is removed • Used when sputum induction is not productive, or other diseases are being considered

• Direct removal of sputum from the lung. Will not have saliva • No active involvement by patient is required

• • • • •

Gastric washing

• Tube inserted through the patient’s mouth or nose and passed into the stomach to obtain a sample of gastric secretions that contain sputum that has been coughed into the throat and then swallowed • Used to obtain a sputum sample from children who do not produce sputum when they cough

• No active involvement by the patient is required

• Can be uncomfortable for the patient • Must be done as soon as the patient wakes up in the morning • May require a hospital stay

Expensive Invasive Requires special equipment Performed in hospital or clinic Requires anesthesia

Core Curriculum on Tuberculosis: What the Clinician Should Know. 6th ed. Atlanta, GA: Centers for Disease Control and Prevention; 2013. https://www.cdc.gov/tb /education/corecurr/pdf/corecurr_all.pdf. Accessed April 25, 2017.

623

624

CHAPTER 23  Pulmonary Tuberculosis grow slowly, 4–8 weeks are required before growth is detected. Positive cultures for M. tuberculosis confirm the diagnosis of TB disease; however, in the absence of a positive culture, TB disease may also be diagnosed based on clinical signs and symptoms alone.1 Once the growth of M. tuberculosis is detected, it can be sub-cultured onto media containing antibiotics.22 Susceptibility to the first-line anti-TB drugs isoniazid, rifampin, ethambutol, and pyrazinamide is performed to identify multiple-drug-resistant TB (MDR-TB).1,8 The results of drug susceptibility tests direct clinicians to choose the appropriate drugs for treating each patient. Patients with TB disease who are treated with drugs to which their strain of TB is resistant may not be successfully cured. In fact, their strain of TB may become resistant to additional drugs.1 A patient is diagnosed with MDR-TB disease if the organisms are resistant to at least isoniazid and rifampin, the two most potent firstline anti-TB drugs.1

TABLE 23-7 FDA-Approved Anti-TB Drugs Drug Class

Drug Name

Comments

First-line anti-TB drugs

Isoniazid (INH)

INH, RIF, PZA, and EMB form the core of initial treatment regimen.

Rifampin (RIF) Pyrazinamide (PZA) Ethambutol (EMB) Rifapentine (RPT)

Secondline anti-TB drugs

Streptomycin (SM) Cycloserine Capreomycin

KNOWLEDGE CHECK QUESTIONS

Para-aminosalicylic acid

1. True or False: TST in persons vaccinated with BCG should be interpreted using different criteria than for those not BCG vaccinated.

Ethionamide

2. True or False: The best way to obtain specimens from children who are unable to produce sputum is by gastric washing. 3. True or False: Cultures should be done on all diagnostic specimens, regardless of the other bacteriologic examination results. 4. True or False: Resistance to isoniazid, rifampin, ethambutol, and pyrazinamide is required for a diagnosis of MDR-TB.

Treatment and Management Currently, 10 drugs have been approved by the FDA for the treatment of TB disease. See Table 23-7. Also, the fluoroquinolones (levofloxacin, moxifloxacin, and gatifloxacin), although not approved by the FDA for TB disease, are commonly used to treat TB disease caused by drug-resistant organisms or for patients who are intolerant of some first-line drugs.1 The goals of TB treatment are to interrupt transmission, make the patient noninfectious, and prevent morbidity and death by curing patient with TB while preventing the emergence of drug resistance.8 A few basic treatment regimens are recommended for treating adults with TB disease caused by organisms that are known or presumed to be susceptible to isoniazid (INH), rifampin (RIF), pyrazinamide (PZA),

RPT may be used once weekly with INH in the continuation phase of treatment for HIV-negative patients with noncavitary, drug-susceptible pulmonary TB who have negative sputum smears at the completion of the initial phase of therapy. Increasing prevalence of resistance to SM in many parts of the world has decreased its overall usefulness. SM was formerly a first-line anti-TB drug. SM is still used in initial treatment.

Courtesy of U.S. Food and Drug Administration.

and ethambutol (EMB). Table 23-8 shows two of these regimens. Each treatment regimen consists of an initial 2-month treatment phase followed by a continuation phase of either 4 or 7 months.1 See Table 23-9. The choice of treatment in the initial phase is usually empiric, as susceptibility data may not be available or become available at the end of the initial phase of treatment. The initial drug regimen is based on the knowledge of the likely drug susceptibility. Four drugs, INH, RIF, PZA, and EMB, are used in the initial phase of previously untreated TB because of concern for INH resistance.1,11 These drugs are well absorbed after oral administration with peak serum levels at 2–4 hours and nearly complete elimination within 24 hours. The drugs are recommended based on their bactericidal activity to rapidly reduce the number of viable organisms and render the patients noninfectious. Sputum AFB smears and cultures need to be obtained at the time of completion of the initial phase of treatment (8 weeks) to identify patients at increased risk of relapse. Once the TB isolate is known to be fully susceptible, ethambutol can be discontinued. After 2 months of therapy, pyrazinamide can be stopped. The duration of therapy depends on the drugs used, the drug susceptibility test results of the isolate, and the patient’s response to therapy. Many patients with untreated pulmonary TB disease can be managed with either a 6-month or a 9-month regimen, although the 6-month regimen is used for most patients.1

Treatment and Management

TABLE 23-8 Recommended Drug Regimens for Adults with Drug-Susceptible Organisms Initial Phase

Continuation Phase

Regimen

Drugs

Duration

Regimen

Drugs

Duration

1

INH, RIF, PZA, EMB

2 months*

1a

INH, RIF

4 months*

1b

INH, RPT

4 months*

2

INH, RIF

7 months*

2

INH, RIF, EMB

2 months*

*There are several combinations of doses and days/week these medications may be administered. Patients on regimens given less than 7 days/week should receive direct observation therapy. Regimens given less than 3 times/week are not recommended for HIV-infected patients. Core Curriculum on Tuberculosis: What the Clinician Should Know. 6th ed. Atlanta, GA: Centers for Disease Control and Prevention; 2013. https://www.cdc.gov/tb /education/corecurr/pdf/corecurr_all.pdf. Accessed April 25, 2017.

TABLE 23-9 Phases of TB Disease Treatment Phase

Purpose

Treatment

Initial phase

• Kills most of the tubercle bacilli • Prevents the emergence of drug resistance • Determines the outcome of the regimen

• The duration is 2 months • Most often includes four drugs (INH, RIF, PZA, and EMB) • Multiple drugs are needed to prevent the development of drug-resistant TB disease

Continuation phase

• Kills remaining tubercle bacilli (after initial phase) • If continuation phase is not utilized, surviving bacilli may cause TB disease in the patient later on

• Duration is either 4 or 7 months • 4 months is used for most patients • 7 months is recommended only for persons • Who have drug-susceptible cavitary or extensive pulmonary TB disease and whose sputum culture obtained at the end of the initial phase is positive • Whose initial phase of treatment did not include PZA • Who are treated with once-weekly INH and RPT and whose sputum culture at the end of the initial phase is positive

Treatment completion

Defines the number of doses ingested within a specific time frame Duration depends on • Drugs used • Drug susceptibility test results of the isolate • Patient’s response to therapy

Most patients with previously untreated pulmonary TB disease can be treated with either • 6-month regimen (preferred) containing INH, RIF, and initially PZA Or • 9-month regimen containing INH and RIF

Core Curriculum on Tuberculosis: What the Clinician Should Know. 6th ed. Atlanta, GA: Centers for Disease Control and Prevention; 2013. https://www.cdc.gov/tb /education/corecurr/pdf/corecurr_all.pdf. Accessed April 25, 2017.

The continuation phase of treatment for pulmonary TB is administered for 4 or 7 months and, in most cases, consists of INH and RIF. Treatment completion is defined primarily as the ingestion of the total number of doses prescribed within the specified time frame.8 The duration of therapy depends on the drugs used, the drug susceptibility test results of the isolate, and the patient’s response to therapy.1,8,11 Routine follow-up after treatment is not necessary for patients who have had a satisfactory response to a 6- or 9-month regimen with both INH and RIF. Patients whose organisms were fully susceptible to the drugs being used should be instructed to promptly report the development of any symptoms, particularly prolonged cough, fever, or weight loss. State and local health departments have the primary responsibility for preventing and controlling TB.

However, TB control is a complex undertaking and requires the collaborative efforts of a broad range of persons, organizations, and institutions both inside and outside the public health sector. These various persons and organizations have a role in improving the detection of TB cases, one of the most important responsibilities of TB control.1 Drug-resistant TB disease can develop in two different ways, known as primary and secondary resistance. Primary resistance occurs in persons who are initially exposed to and infected with resistant organisms. Secondary resistance, or acquired resistance, develops during TB therapy, either because the patient was treated with an inadequate regimen or because the patient did not adhere to the prescribed regimen appropriately or because of other conditions such as drug malabsorption or drug–drug interactions leading to low serum levels.1

625

626

CHAPTER 23  Pulmonary Tuberculosis When initiating treatment for MDR-TB, at least 3–5 previously unused drugs for which there is in vitro susceptibility are used. Levofloxacin, which is a fluoroquinolone, has been shown to be the best suited over a long term and should be included in the regimen.11 Other drugs that are used, but not FDA approved for TB treatment, include amikacin, capreomycin, kanamycin, levofloxacin, ciprofloxacin, ofloxacin, prothionamide, terizidone, and bedaquiline.11 Any patients who have a clinically significant result on TST or a positive IGRA result should receive a course of therapy for latent TB, once active infection and disease are ruled out. Recommendations from the CDC include the use of INH individually for either 9 or 6 months, INH and RPT for 3 months, or RIF for 4 months. The duration of LTBI treatment depends on the patient. However, the preferred regimen is daily treatment with INH for 9 months.1 The efficacy of treatment and presence of adverse reactions to therapy require evaluation by clinicians. There are three methods to determine whether a patient is responding to therapy. These methods include clinical evaluation, bacteriological examination, and chest radiograph. During the initial therapy, patient symptoms should gradually improve and eventually go away. If not, the patient may have regimen adherence issues and develop drug resistance.1

KNOWLEDGE CHECK QUESTIONS 1. True or False: The initial treatment phase for TB disease consists of 6 months of treatment. 2. True or False: The initial treatment phase typically consists of four medications. 3. True or False: A LTBI requires the same treatment as active TB disease. 4. True or False: Treatment for MDR-TB includes using at least three to five previously unused anti-TB drugs.

Prognosis TB disease now ranks alongside HIV as a leading cause of death worldwide.4 There are several factors that directly affect the prognosis of a person with TB disease. These factors include alcohol abuse, age, HIV infection, comorbidities of malignancy, renal disease, and respiratory disorders and malnutrition.24,25 Comorbidity has a significant effect on the survival of patients with TB disease, and it is a poor prognostic indicator that needs consideration regardless of sputum conversion.26 Other important predictors of mortality include socioeconomic status, multidrug resistance, and delayed

diagnosis.27–29 The absence of respiratory symptoms, including a chronic cough and dyspnea, are significant factors associated with early mortality within 30 days, making early diagnosis and treatment important features in improving the outcome of TB disease.30 With early diagnosis and adequate treatment, almost all patients will recover and be cured.1

KNOWLEDGE CHECK QUESTIONS 1. True or False: Comorbidities have no influence on the outcome of TB disease treatment. 2. True or False: Given adequate treatment, almost all patients will recover and be cured.

Chapter Summary TB is an airborne disease caused by M. tuberculosis. These bacteria are carried in droplet nuclei or airborne particles that are between 1 and 5 µm in diameter. People can handle the mycobacterium in one of three ways. A person’s immune system can clear the infection. A person’s immune system can suppress the organism into a dormant state called LTBI. Latent TB is not communicable. However, the microbes may be activated later on in life if the person’s immune system becomes weak, causing secondary TB. A person’s immune system can be overwhelmed on initial exposure, causing primary TB. LTBI can be detected by either TST or IGRAs or both. TB disease is diagnosed using physical ­examination along with chest radiography and bacteriological examination. The organism is tested for susceptibility to at least two of the first-line medications. There are currently five first-line medications and five second-line medicines, approved by the FDA, for the treatment of TB disease. TB disease is always treated with multiple drugs. The number and types of drugs used depend on the organism’s susceptibility, the patient’s response to therapy, and the phase of treatment.

Key Points 1. TB is an airborne disease caused by the rodshaped, non-spore-forming, acid-fast, aerobic bacterium M. tuberculosis. 2. M. tuberculosis is carried in airborne particles called droplet nuclei that are 1–5 µm in diameter. 3. TB most commonly affects the lungs but can also occur in almost any anatomical site. 4. Sputum specimen is obtained from spontaneous samples, sputum induction, bronchoscopy, bronchoalveolar lavage, or gastric washing to culture M. tuberculosis for the diagnosis of TB disease.

Chapter Questions 5. Factors that influence the clinical features of TB disease include host–organism interaction, host endogenous factors, and organism factors. 6. The most common symptom of pulmonary TB disease is a cough. 7. TB disease is one of the top 10 causes of death worldwide and in 2015 caused more deaths than HIV. 8. The host immune system can clear the TB infection, suppress the TB infection into latent TB (which may become active years later), or be overwhelmed by the infection and lead to the onset of active (primary) disease. 9. Risk factors for developing TB disease include recent infection with TB bacteria and those individuals with weakened immune systems. 10. Hemoptysis is the most frequently occurring complication of TB disease. 11. Testing for latent TB includes TST and IGRAs. 12. Diagnostic testing to identify TB disease in patients relies on the use of chest radiography, acidfast smears of sputum specimen, NAA testing, culturing, and drug susceptibility testing. 13. The goals of TB treatment are to interrupt the transmission of the disease by rendering a patient noninfectious, prevent patient morbidity and mortality, and avoid the development of drug-resistant strains. 14. The three phases of TB therapy include the initial phase (2 months), the continuation phase (4–7 months), and treatment completion (depends on the drug used, organism susceptibility, and patient response). 15. Multiple drug therapy is always used to treat TB disease. 16. Comorbidity has a significant effect on the prognosis for TB disease.

Chapter Questions 1. Mycobacterium tuberculosis is ___________. a. non-spore forming and anaerobic b. rod shaped and aerobic c. spore forming and aerobic d. spherical and anaerobic 2. The purpose of a sputum smear is to identify _________. a. leukocytes b. gram-negative bacilli c. acid-fast bacilli d. drug-resistant bacilli 3. The specimen collection process that best suits small children who cannot produce sputum is _____________. a. transbronchial needle aspiration b. sputum induction c. bronchoalveolar lavage d. gastric washing

4. Endogenous factors that influence the clinical manifestations of tuberculosis disease include all of the following except _______________. a. host immunocompetence b. the host country of origin c. immunization with bacillus Calmette–Guérin d. the presence of comorbidities 5. The most common symptom of tuberculosis (TB) disease is __________. a. cough b. night sweats c. foul-smelling sputum d. pleuritic chest pain 6. The most common hematologic findings of TB ­disease is _____________. a. polycythemia b. hypernatremia c. leukocytosis d. reduced erythrocyte sedimentation 7. In 2011, the TB disease rate in the United States was the highest for which race/ethnicity? a. Non-Hispanic white b. African American c. Hispanic d. Asian 8. Once exposed, how long does it take M. tuberculosis to grow, within a host, until they reach 1,000 to 10,000 in number? a. 2–12 weeks b. 4–16 weeks c. 6–18 weeks d. 8–20 weeks 9. ______________________ is(are) the most common site for tuberculosis to affect the human body. a. Kidneys b. Liver c. Lungs d. Central nervous system 10. Which of the following statements about TB is true? a. Latent tuberculosis infection (LTBI) and TB disease both begin with macrophage production of proteolytic enzymes and cytokines. b. Tubercle bacilli are in the body only with ­tuberculosis disease. c. Granulomas are present with immunocompromised individuals exposed to TB. d. Individuals with LTBI can spread the ­tuberculosis TB disease. 11. The primary lesion in active pulmonary TB may spontaneously heal into a __________________. a. Ghon lesion b. tuberculoma c. granuloma d. Ghon focus

627

628

CHAPTER 23  Pulmonary Tuberculosis 12. Which of the following is true concerning the characteristics of LTBI? a. Smears and cultures are positive for LTBI. b. Isolation precautions are necessary for LTBI. c. The bacilli are alive but inactive with LTBI. d. There are a large number of bacilli in the body with LTBI. 13. Cavitation in the lungs from bacilli dissemination occurs most often in the ___________. a. basal portion of the lower lobes b. middle lobes c. lower portion of the upper lobes d. apices of the upper lobes 14. A common complication of active pulmonary TB is ___________. a. hemoptysis b. necrosis c. lymph obstruction d. pleural effusion 15. Following exposure to TB, it takes the body’s immune system approximately ____________________ to react to the tuberculin skin test. a. 48–72 hours b. 2–8 weeks c. 8–12 days d. 4 months 16. The gold standard for the definitive (confirmation) diagnosis of active pulmonary tuberculosis disease is the ____________. a. culture and examination of a clinical specimen b. tuberculin skin test c. acid-fast stain d. nucleic acid amplification tests 17. A patient is diagnosed with multiple-drug-resistant tuberculosis (MDR-TB) when the M. tuberculosis is resistant to at least ___________. a. ethambutol and rifampin b. capreomycin and ethionamide c. streptomycin and isoniazid d. isoniazid and rifampin 18. The initial treatment phase for pulmonary TB disease is _________. a. 2 months b. 4 months c. 6 months d. 8 months 19. The continuation phase of treatment for pulmonary TB disease is ______________. a. 1–3 months b. 4–7 months c. 5–6 months d. 6–12 months

20. The anti-TB drug that has been shown to be the best suited for a long-term MDR-TB regimen is ____________. a. kanamycin b. prothionamide c. levofloxacin d. ciprofloxacin

References 1. Core Curriculum on Tuberculosis: What the Clinician Should Know. 6th ed. Atlanta, GA: Centers for Disease Control and Prevention; 2013. https://www.cdc.gov/tb/education/corecurr/pdf/corecurr_all .pdf. Accessed April 25, 2017. 2. Diagnostic Standards and Classification of Tuberculosis in Adults and Children. This official statement of the American Thoracic Society and the Centers for Disease Control and Prevention was adopted by the ATS Board of Directors, July 1999. This statement was endorsed by the Council of the Infectious Disease Society of America, September 1999. Am J Respir Crit Care Med. 2000; 161(4 Pt 1):1376–1395. 3. Hershkovitz I, Donoghue H, Minnikin D, et al. Detection and molecular characterization of 9000-year-old M. tuberculosis from a Neolithic settlement in the Eastern Mediterranean. PLoS ONE. 2008;3(10):e3426. doi:10.1371/journal.pone.0003426. 4. World Health Organization. Global Tuberculosis Report 2016. World Health Organization; 2016. http://www.who.int/tb/publications /global_report/en. Accessed March 12, 2017. 5. Knechel N. Tuberculosis: pathophysiology, clinical features, and diagnosis. Crit Care Nurs. 2009;29(2):34–43. doi:10.4037/ ccn2009968. 6. Rieder H, Snider D, Cauthen G. Extrapulmonary tuberculosis in the United States. Am Rev Respir Dis. 1990;141(2):347–351. doi:10.1164/ajrccm/141.2.347. 7. Slutsker L, Castro K, Ward J, Dooley S. Epidemiology of extrapulmonary tuberculosis among persons with AIDS in the United States. Clin Infect Dis. 1993;16(4):513–518. doi:10.1093/clind /16.4.513. 8. Raviglione M, O’Brien R. Tuberculosis. In: Loscalzo J, ed. Harrison’s Pulmonary and Critical Care Medicine. 2nd ed. New York, NY: McGraw-Hill Education; 2013:121–146. 9. Lee S, Meintjes G, Kamarulzaman A, Leung C. Management of tuberculosis and latent tuberculosis infection in human immunodeficiency virus-infected persons. Respirology. 2013;18(6):912–922. doi:10.1111/resp.12120. 10. CDC | TB | Data and Statistics. 2017. https://www.cdc.gov/tb /statistics. Accessed May 9, 2017. 11. Herchline T. Tuberculosis: practice essentials, background, pathophysiology. Medscape. 2016. http://emedicine.medscape.com /article/230802-overview. Accessed May 17, 2017. 12. Dheda K, Booth H, Huggett J, Johnson M, Zumla A, Rook G. Lung remodeling in pulmonary tuberculosis. J Infect Dis. 2005;192(7): 1201–1209. doi:10.1086/444545. 13. Ong C, Elkington P, Friedland J. Tuberculosis, pulmonary cavitation, and matrix metalloproteinases. Am J Respir Crit Care Med. 2014;190(1):9–18. doi:10.1164/rccm.201311-2106pp. 14. CDC | TB | Basic TB Facts | TB Risk Factors. 2017. https://www .cdc.gov/tb/topic/basics/risk.htm. Accessed May 24, 2017. 15. Johnston H, Reisz G. Changing spectrum of hemoptysis. Underlying causes in 148 patients undergoing diagnostic flexible fiberoptic bronchoscopy. Arch Intern Med. 1989;149:1666–1668. 16. Conlan AA, Hurwitz SS, Krige L, et al. Massive hemoptysis. Review of 123 cases. J Thorac Cardiovasc Surg. 1983;85:120–124.

References 17. Wilder RJ, Beacham EG, Ravitch MM. Spontaneous pneumothorax complicating cavitary tuberculosis. J Thorac Cardiovasc Surg. 1962;43:561–573. 18. Ihm HJ, Hankins JR, Miller JE, McLaughlin JS. Pneumothorax associated with pulmonary tuberculosis. J Thorac Cardiovasc Surg. 1972;64:211–219. 19. Aktoğu S, Yorgancioglu A, Cirak K, et al. Clinical spectrum of pulmonary and pleural tuberculosis: a report of 5,480 cases. Eur Respir J. 1996;9:2031–2035. 20. Bobrowitz ID, Rodescu D, Marcus H, Abeles H. The destroyed tuberculous lung. Scand J Respir Dis. 1974;55:82–88. 21. Palmer PE. Pulmonary tuberculosis—usual and unusual radiographic presentations. Semin Roentgenol. 1979;14:204–243. 22. Cudahy P, Shenoi S. Diagnostics for pulmonary tuberculosis. Postgrad Med J. 2016;92(1086):187–193. doi:10.1136/postgradmedj-2015 -133278. 23. Lewinsohn D, Leonard M, LoBue P, et al. Official American Thoracic Society/Infectious Diseases Society of America/Centers for Disease Control and Prevention Clinical Practice Guidelines: Diagnosis of Tuberculosis in Adults and Children. Clin Infect Dis. 2017;64(2):111–115. doi:10.1093/cid/ciw778. 24. Sterling T, Zhao Z, Khan A, et al. Mortality in a large tuberculosis treatment trial: modifiable and non-modifiable risk factors. Int J Tuberc Lung Dis. 2006;10(5):542–548.

25. Kim H, Lee C, Shin S, et al. The impact of nutritional deficit on mortality of in-patients with pulmonary tuberculosis. Int J Tuberc Lung Dis. 2010;14(1):79–85. 26. Oursler K, Moore R, Bishai W, Harrington S, Pope D, Chaisson R. Survival of patients with pulmonary tuberculosis: clinical and molecular epidemiologic factors. Clin Infect Dis. 2002;34(6):752–759. doi:10.1086/338784. 27. Kliiman K, Atraja A. Predictors and mortality associated with treatment default in pulmonary tuberculosis. Int J Tuberc Lung Dis. 2010;14(4):454–463. 28. Liu Y, Lin H, Chen Y, et al. Reduced health provider delay and tuberculosis mortality due to an improved hospital programme. Int J Tuberc Lung Dis. 2010;14(1):72–78. 29. Kawai V, Soto G, Gilman R, et al. Tuberculosis mortality, drug resistance, and infectiousness in patients with and without HIV infection in Peru. Am J Trop Med Hyg. 2006;75(6):1027–1033. doi:10.4269/ajtmh.2006.75.1027. 30. Feng J, Su W, Chiu Y, et al. Initial presentations predict mortality in pulmonary tuberculosis patients—a prospective observational study. PLoS One. 2011;6(9):e23715. doi:10.1371/journal.pone.0023715.

629

CHAPTER

24 © TairA/Shutterstock

Neonatal and Pediatric Pulmonary Disorders

“You treat a disease, you win, you lose. You treat a person, I guarantee you, you’ll win, no matter what the outcome.” —Patch Adams

OUTLINE Introduction Neonatal Delivery Room Care Apnea of Prematurity Meconium Aspiration Congenital Heart Defects Infant Respiratory Distress Syndrome Bronchopulmonary Dysplasia Transient Tachypnea of the Newborn Congenital Diaphragmatic Hernia Pediatrics Croup Epiglottitis Bronchiolitis Foreign Body Obstruction

OBJECTIVES 1. Describe the abnormalities underlying neonatal and pediatric pulmonary disorders. 2. Review the development, etiology, and pathophysiology of the various pulmonary disorders in newborns, infants, and children. 3. Discuss the clinical manifestations associated with each type of neonatal and pediatric pulmonary disorder. 4. Explain diagnostic testing used in analyzing each type of pulmonary disorder seen in newborns, infants, and children.

5. Recognize and manage various neonatal and pediatric pulmonary disorders. 6. Identify clinical treatment options available for the various pulmonary disorders in newborns, infants, and children. 7. Define the complications and prognosis primarily associated with the various neonatal and pediatric pulmonary disorders.

KEY TERMS Apgar scores Apnea of prematurity (AOP) Bronchiolitis Bronchopulmonary dysplasia (BPD) Central apnea Congenital diaphragmatic hernia (CDH) Congenital heart defect (CHD) Croup Epiglottitis Extracorporeal membrane oxygenation (ECMO) Fetal heart rate (FHR) Fetal hypoxic stress Fetal ultrasonography Foreign body aspiration Foreign body obstruction (FBO)

Golden minute Heliox Infant respiratory distress syndrome (IRDS) Meconium Meconium aspiration syndrome (MAS) Mixed apnea Persistent pulmonary hypertension of the newborn (PPHN) Prematurity Respiratory syncytial virus (RSV) Scalp blood sampling Surfactant Surfactant replacement therapy Transient tachypnea of the newborn (TTN)

631

632

CHAPTER 24  Neonatal and Pediatric Pulmonary Disorders

Introduction Cardiopulmonary diseases represent the most common cause of death in infants and children worldwide. Proper knowledge of the etiology and pathophysiology of various cardiopulmonary disorders in the neonate and pediatric patient is fundamental to effective patient care. Neonatal and pediatric airways are different than those of adults, and these patients are prone to rapid status changes. Recognizing, managing, and treating these disorders require an understanding of how a diagnosis presents, the predisposed condition, and treatment options available. This essential knowledge base can improve patient care and allow the child to thrive, especially in the medical field. This chapter will focus on the etiologic and pathophysiologic characteristics of the most common neonatal and pediatric cardiopulmonary disorders of the respiratory system. It will focus on the clinician understanding the complexity of the diseases and engaging in potential management strategies to improve outcomes.

Neonatal There are several differences between the respiratory system of the neonate and that of a pediatric patient. The following sections will focus on the neonatal aspects and will cover everything from what to expect in the delivery room to the numerous afflictions that can affect newborns.

Delivery Room Care The birth of a baby in the delivery room is one of the most extraordinary moments in healthcare. In 2015, the number of babies born in the United States was just shy of 4 million.1 Most of these newborns will need routine clinical attention; however, roughly 1% may require extensive postdelivery medical care. The outcomes of these challenging newborns can be enhanced through proper patient assessment and efficient neonatal resuscitation. Prior to delivery, it is important to check that all necessary equipment (e.g., intubation tray) is present and functioning properly. The delivery room setup is imperative. The room should be warm, the radiant warmer turned on, and warm towels available. Lastly, the maternal case notes should be viewed for any relevant information, specifically searching for risk factors associated with pulmonary disorders. Based on findings, clinicians should anticipate the need for potential resuscitation and gather the applicable personnel and equipment to ensure the patient care team responds in a suitable and successful manner. Various methods, including fetal heart rate (FHR) monitoring and scalp blood sampling, can be used to evaluate fetal health during labor and delivery.2 FHR monitoring can help to detect irregularities in normal heart patterns.2 Trends in FHR are used to estimate fetal tolerance,

help prevent unnecessary treatments, and guide the patient care team in making clinical decisions.2 Fetal scalp blood sampling is a monitoring practice that uses pH to verify whether fetal oxygenation is sufficient.3,4 A low fetal scalp pH is considered abnormal and may mean that the baby is not tolerating labor very well.3,4 Following delivery, the newborn should be assessed right away. If a neonate passes the initial assessment then the baby should remain with the mother. However, if a neonate is failing to thrive upon examination then a neonatal resuscitative algorithm should be initiated (Figure 24-1). Clinicians have approximately 60 seconds, the golden minute, to complete the preliminary evaluation and initiate the resuscitative interventions.5 A brief physical exam, including Apgar scoring, vital signs, and other procedures, should be performed. It is the responsibility of the clinicians attending the delivery to ensure that the infant is provided proper care, immediately examined for problems, and given any resuscitation that may be needed. The first few minutes following delivery may determine the quality of life of a patient.6 If neonatal breathing is not adequate, the ABCs (i.e., airway, breathing, circulation) of resuscitation should be followed. A patent airway is obtained through repositioning the infant’s head and carefully suctioning to clear secretions.7 If breathing efforts are shallow, gentle stimulation and supplemental oxygen therapy may be required. Clinicians must thoroughly understand the adverse effects of excessive and insufficient oxygen delivery to the newborn. Failure to establish spontaneous breathing indicates the need for positive pressure ventilation (via face mask) or even endotracheal intubation and assisted ventilation.7 Clinicians should ventilate at an appropriate respiratory rate, observe chest movement, and listen for heart and breath sounds. Assessment of circulation is done through heart rate monitoring, palpation, and skin color check of the infant. Chest compressions, medications, and volume expanders may be started if the heart rate drops and remains below 60 beats/minute.7 Newborns needing resuscitative measures in the delivery room should be transported to the neonatal intensive care unit (NICU) for close monitoring as well as for additional management and treatment.

Apnea of Prematurity In recent years, the understanding of the anatomy and physiology of neonatal breathing has increased. In utero, breathing is intermittent but becomes continuous following birth.8,9 After birth, apnea of prematurity (AOP) or the cessation of breathing efforts is a key concern of ICU nursery clinicians. This neonatal condition is the most common form of newborn apnea and causes significant increases in morbidity and mortality rates.9 Clinicians must be able to properly differentiate the various clinical definitions

Neonatal

Antenatal counseling Team briefing and equipment check

Birth

Yes

1 minute

Term gestation? Good tone? Breathing or crying?

Infant stays with mother for routine care: warm and maintain normal temperature, position airway, clear secretions if needed, dry. Ongoing evaluation

No Warm and maintain normal temperature, position airway, clear secretions if needed, dry, stimulate No

Apnea or gasping? HR below 100/min? Yes

Labored breathing or persistent cyanosis? Yes Position and clear airway, SpO2 monitor Supplementary O2 as needed Consider CPAP

PPV SpO2 monitor Consider ECG monitor

No

HR below 100/min?

Postresuscitation care Team debriefing

Yes Check chest movement Ventilation corrective steps if needed ETT or laryngeal mask if needed

No

HR below 60/min? Yes Intubate if not already done Chest compressions Coordinate with PPV 100% O2 ECG monitor Consider emergency UVC

HR below 60/min? Yes IV epinephrine If HR persistently below 60/min Consider hypovolemia Consider pneumothorax

Targeted preductal SpO2 after birth 1 min: 60–65% 2 min: 65–70% 3 min: 70–75% 4 min: 75–80% 5 min: 80–85% 10 min: 85–95%

FIGURE 24-1  American Heart Association neonatal resuscitative algorithm. ETT, endotracheal tube; HR, heart rate; PPV, positive pressure

ventilation.

Reproduced with permission from Wyckoff MH, et al. (2015). Part 13: Neonatal resuscitation: 2015 American Heart Association guidelines update for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation, 132(18 suppl 2), S543–S560.

involved in this disorder. Apnea, in general, is defined as the cessation of breathing.8,9 Remember that apnea can be classified into three subcategories: central, obstructive, or mixed apnea. Central apnea is a complete interruption in the effort to breathe.8,10 Obstructive

apnea is absent respiratory airflow in the presence of continued efforts.8,10 Mixed apnea contains elements of both central and obstructive apnea symptoms.8,10 AOP is a result of immature respiratory control developing into a disorder most commonly defined as the cessation

633

CHAPTER 24  Neonatal and Pediatric Pulmonary Disorders of respiratory airflow for more than 20 seconds or the cessation of respiratory airflow for less than 20 seconds if complemented by bradycardia or oxygen (O2) desaturations8 in neonates with less than 37 weeks’ maturation.

Clinical Signs and Symptoms It is the responsibility of the bedside clinician to identify the problem through a physical examination and thorough patient assessment. Clinical symptoms associated with apnea, including bradycardia and oxygen desaturations, must be documented.11 Physical observation of the neonate’s breathing patterns, sleeping positions, and lying postures should be noted. Further assessment of infant apnea should include identification of airway deformities (e.g., choanal atresia, jaw anomalies, or neck masses) as well as any distant organ disorders that potentially affect breathing (e.g., brain hemorrhages, seizures, or congenital heart disease).11 Other clinical symptoms include choking, snoring, and mouth breathing; however, in some newborn cases, no additional respiratory distress signs may present.11 Added fluctuations in skin color, breathing pattern, or muscle tone may result.11 Monitoring of the infant’s cardiac, neurologic, and respiratory statuses may reveal supplemental clinically significant findings.

Etiology Over the years, several aspects of causation have been proposed because the etiology of AOP is not fully understood. As it stands, when all other causes of apnea have been eliminated, a premature infant may be considered to have AOP.12,13 This clinical phenomenon is associated with unorganized, yet interconnected brain stem neurons and their responses to stimuli (e.g., respiratory system).12,13 This immature respiratory control system is represented in abnormal breathing patterns seen during apnea episodes. There are two types of apnea related to this disorder at birth. An increased respiratory rate and depth indicates primary apnea.12,13 During this primary stage, infants usually respond to stimulation measures.12,13 When asphyxia is allowed to continue, the infant may suffer from a period of gasping respirations as well as a falling heart rate and blood pressure.12,13 This secondary stage requires resuscitation. In some cases, it can be difficult to distinguish primary from secondary apnea, so many clinicians, therefore, assume any apnea at birth requires immediate artificial respiration.12,13

Epidemiology AOP is the most common problem in premature infants. During their hospital stay, nearly 70% of infants born at 34 weeks gestational age or younger have clinically significant apnea episodes14 (Figure 24-2). Simply put, the more premature the infant, the higher the

Relative Incidence of Apnea

634

SIDS (m ± SD)

Pre-term

Term

3 mos

6 mos

Age Apnea of prematurity 24 weeks GA 40 weeks GA FIGURE 24-2  Apnea of prematurity. GA, gestational age. Reproduced with permission from American Academy of Pediatrics.

risk of AOP. Research findings have shown that AOP may not resolve at full term and the condition may persist for some time following discharge.15 Family members and other caregivers must be well trained in in-home monitoring, infant care, and cardiopulmonary resuscitation.

Pathology/Pathophysiology Premature infants with AOP are considered susceptible to impaired chemoreceptors, immature lung and airway receptors, as well as an inhibited central nervous system (CNS).16,17 This depression of the central respiratory drive output mechanism to the muscles is depicted as the key element in the pathogenesis of AOP.16,17 Sleep and sleep state are major contributing factors in apnea as well. When compared with full-term infants, preterm infants have more frequent REM sleep episodes, resulting in larger sleep cycles spent in respiratory depression.18

Risk Factors There are numerous causes of apnea in premature infants. A mixture of inappropriate neural signaling and airway obstruction typically triggers apneic episodes in these patients; however, underlying pathologies, including sepsis, necrotizing enterocolitis (NEC), asphyxia, respiratory distress, infection, gastroesophageal reflux disease (GERD), and cardiovascular disorders, may also be causes of neonatal apnea.19 AOP is specifically a developmental disorder. Risk factors significantly associated with AOP include a fetal birth weight of fewer than 1,500 g, hypotension, GERD, and the immediate need for postdelivery positive pressure ventilation.19

Complications Regardless of past medical history, premature infants are at an increased risk for apnea episodes following

Neonatal administration of anesthetics or sedatives.12 As a result of this increased risk, allowing the infant’s respiratory control system to mature before performing elective surgery is highly recommended.

Diagnostic Testing Research has shown that highly trained clinicians miss nearly 50% of all AOP cases.20 Due to this high prevalence, preterm infants with a 35-week or less gestational age should be monitored for apnea.20 Clinicians must familiarize themselves with the benefits and drawbacks of sophisticated monitoring tools used to improve bedside detection of AOP. Neonates with frequent apnea episodes following birth should receive routine diagnostic tests, including a chest radiograph (CXR), electrocardiogram (ECG) monitoring, arterial blood gas (ABG) analysis, and complete blood count (CBC).8 Cultures of blood, urine, and spinal fluid should be performed if a serious infection is suspected.20 Cardiorespiratory monitors are essential for not only identifying AOP but furthermore for continuous monitoring of the infant’s blood pressure and heart rate.20 Pulse oximetry may be useful in revealing hypoxemia, but clinicians must be aware of the issues (e.g., potential recording delay) surrounding these diagnostic tools. Impedance pneumography is another commonly used instrument that monitors a patient’s apneic events.20 Through the use of electrodes, this device tracks respiratory volume and breathing rate. Impedance pneumography in combination with a nasal thermistor may be clinically used to distinguish types of apnea.8,21 A nasal thermistor is a conventional respiratory airflow-recording device that measures temperature as an alternate of flow.8,21 Obtaining a polysomnographic recording is the recommended diagnostic standard because it provides sufficient information on chest wall movement measurements, airflow changes, oxygen saturation, and heart rate trends.8,21 The severity and duration of these apneic events through nasal airflow, thoracic impedance, oxygen saturation, and heart rate monitoring must be accurately noted. Patient care teams commonly rely heavily on documentation to make bedside management decisions. Through the use of standardized approaches, precise diagnosis of AOP can be improved.

Treatment and Management Treatment goals should focus on addressing the underlying cause of the apnea, providing appropriate patient management, and preventing further occurrences. This begins with monitoring, identifying, and treating the primary disease process—ineffective breathing potentially resulting in apnea. Defining escalating treatment options can be an effective management strategy. Depending on the severity and frequency of AOP, common treatments include stimulation, assisted ventilation, or methylxanthine therapy.22 Using high-flow nasal

cannula (HFNC) oxygen therapy may alleviate airway occlusions enough to reduce obstructive apnea events.23 Further research is still needed to determine the usefulness of this therapy method. Sometimes it is as simple as fetal tactile stimulation (i.e., rubbing the back); however, if the problem persists, more advanced therapies may be required. Bag-mask ventilation may be initiated when bradycardic or hypoxemic episodes require assistance. Assisted ventilation (e.g., nasal continuous positive airway pressure [CPAP] or invasive ventilation) to manage severe AOP can be life saving. To prevent hyperoxia and the associated risk of retinopathy of prematurity (ROP), Fio2 levels should be limited to maintaining adequate fetal oxygenation statuses.23 Following prolonged apneic episodes, a low dose of a methylxanthine compound, including caffeine, theophylline, or aminophylline, may be administered to promote respiratory stimulation.22 Recently, safety concern questions have been raised regarding the use of methylxanthines in the treatment of AOP. Early reports indicate a potential risk for decreased cerebral blood flow in patients following medication administration.22 Clinical trials related to the safety of methylxanthines in preterm infants with AOP are ongoing.12,22

Prognosis Prognosis is excellent. In infants born prematurely, apnea episodes gradually decrease following the first few months of postpartum life.23 In some cases, however, apnea events may continue until 44 weeks after conception.23 If apneic episodes persist, the neonate should be evaluated for secondary causes of apnea, including neurologic issues or GERD.

Meconium Aspiration Meconium aspiration or

meconium aspiration syndrome (MAS) is the passage

of stained bowel discharge before, during, or following birth.24 Meconium is a dark-green substance composed mainly of water, amniotic fluid, mucus, and other intestinal debris.24 Meconium itself is sterile and harmless; however, if inhaled into the lungs, it can cause serious distress to the newborn. Complications including airway obstruction or lung inflammation, leading to infections, can be life threatening.24 Because meconium is rarely found in the amniotic fluid in infants less than 34 weeks’ gestational age, MAS primarily affects the term or near-term infants and is associated with increased morbidity and mortality.25 The longer a pregnancy continues, the higher the likelihood of the passage of meconium.

Clinical Signs and Symptoms Patients with MAS are usually term or post-term infants delivered through meconium staining and who have already faced substantial fetal hypoxic stress.

635

636

CHAPTER 24  Neonatal and Pediatric Pulmonary Disorders Past medical history most likely includes prolonged labor, breech delivery, as well as inconsistent fetal heart tracings.26,27 Following delivery, severe respiratory distress may be present. Thicker meconium usually correlates with more severe respiratory symptoms. Signs including cyanosis, end-expiratory grunting, nasal flaring, intercostal retractions, and tachypnea may also be observed.26,27 Contingent on the degree of hypoxia, some infants may exhibit low Apgar scores. Physical examination symptoms may include a mature infant with yellow-green staining of skin (e.g., nails and umbilical cord), and green urine, and the umbilical cord may have limited Wharton jelly (i.e., gelatinous substance).26,27 In some cases, auscultation of the chest reveals rhonchi, diminished aeration, as well as a barrel chest (i.e., increased anteroposterior [AP] diameter) due to the manifestation of air trapping.26,27

Etiology Factors such as chronic maternal hypertension, placental insufficiency (i.e., inadequate supply of nutrients), preeclampsia (i.e., gestational hypertension), oligohydramnios (i.e., deficiency of amniotic fluid), infections, and ongoing maternal drug use can all potentially promote the passage of meconium in utero.25

Epidemiology In the United States, meconium staining occurs in nearly 8–25% of all births, significantly increasing in pregnancies continuing past 42 weeks.25,28 Approximately 10% of infants delivered through meconium staining develop MAS.25,28 Additionally, 30% of MAS-diagnosed infants will require intubation and mechanical ventilation.25,28 Changes in obstetric/neonatal approaches appear to be decreasing these numbers.

Rest

Pathology/Pathophysiology Meconium passage results from fetal hypoxic stress in utero. Theoretically, as childbirth approaches, the gastrointestinal (GI) tract matures and vagal stimulation causes relaxed rectal sphincter tone, leading to the passage of meconium into the amniotic fluid.29 The possibility of aspiration always exists, but odds increase with fetal hypoxic stress because of potential gasping breaths and greater respiratory efforts in utero.29 The pathophysiologic effects of meconium staining include increased risk of infection and perinatal aspiration, resulting in four major pulmonary consequences: airway obstruction, surfactant dysfunction, chemical pneumonitis, and pulmonary hypertension.25,30 The amount and consistency of meconium present may lead to significant degrees of airway obstruction. Large amounts of thick meconium may cause complete airway obstruction, resulting in atelectasis and subsequent alveolar collapse.29 A smaller amount of meconium typically causes partial airway obstruction, resulting in alveolar hyperdistension, commonly called the ball-valve effect30 (Figure 24-3). The term ball-valve effect describes the happening of gas being trapped in the lung and potentially rupturing into the pleura, mediastinum, or pericardium.30 It has been suggested that meconium deactivates surfactant and may also compete with surfactant components, thereby inhibiting surfactant synthesis.30 Research has shown that this surfactant hindrance may lead to diffuse atelectasis and decreased pulmonary compliance.30 Following meconium aspiration, inflammation of the airways and a release of cytokines also occur, initiating a diffuse chemical pneumonitis.29 To drastically complicate the clinical picture further, fetal hypoxic stress is suggested to contribute to pulmonary vascular restructuring, resulting in infants quickly developing pulmonary hypertension.29 As one can see, the presence of meconium in the airways has detrimental effects on the newborn.

Inspiration

FIGURE 24-3  Ball-valve effect obstruction by meconium aspiration into the airway. Modified from Koff PB, Eitzman DV, Neu J. Neonatal and Pediatric Care. ed 2. St Louis, MO: Mosby; 1993.

Expiration

Neonatal

Risk Factors Risk factors that increase the likelihood of the development of meconium staining include thicker meconium consistency, inconsistent fetal heart tracings, fetal acidosis, meconium below the cords, cesarean delivery, intubation requirements at birth, and low Apgar scores.25,28 Additionally, research has shown that African American and Pacific Islander infants are at a higher risk for an MAS diagnosis.25,28

Complications MAS complications are extensive and depend on the severity of the disorder as well as the duration and level of treatment required. Assisted ventilation always brings with it a risk of barotrauma or air leak syndrome, especially in situations where the ball-valve effect creates air trapping.31 Increased intracranial pressure is another serious complication in MAS. Compromised infants with unstable vasculature must be regularly assessed for this high incidence complication. As a safety precaution, clinicians should always be closely monitoring high-risk infants for sudden deterioration.

Diagnostic Testing The diagnosis of MAS requires the presence of meconium staining, respiratory distress, as well as radiographic abnormalities. CXR is essential for determining the extent of the disease and any further associated complications. Chest images typically show widespread involvement of acute atelectasis as well as air trapping and hyperexpansion.28,32 Patchy opacities and pleural effusions may be present, especially when an infection develops28,32 (Figure 24-4). Air leaks, including pneumothorax, pneumomediastinum, and pulmonary interstitial emphysema (PIE) are common.28,32

FIGURE 24-4  CXR of MAS. Reproduced from Parenchymal lung disease. Auckland District Health Board. http://www .adhb.govt.nz/newborn/TeachingResources/Radiology/LungParenchyma.htm.

An echocardiogram is necessary to evaluate cardiac function in the setting of pulmonary hypertension or shunting.28,32 ABG assessment of the infant’s acid–base status is crucial in determining V/Q mismatch and hypoxic stress severity. A combination of metabolic acidosis from hypoxic stress and respiratory acidosis from pulmonary hypertension usually develops, resulting in respiratory failure and severe hypoxemia.28,32 ABG measurements, as well as continuous pulse ­oximetry, are essential for proper patient management. Obtaining serum electrolyte concentrations and a CBC can help to ensure adequate selection of treatment modalities.28,32

Treatment and Management Traditionally, national guidelines are provided regarding complicated delivery indications, MAS prevention tactics, and management strategies immediately following delivery. Prevention of MAS is vital: clinicians need to closely monitor neonates in an attempt to better detect distress. Amnioinfusion, an intrapartum intervention, is believed to dilute meconium and thereby minimize aspiration severity in infants identified as at risk for MAS.33 However, a large multicenter study recently reported outcomes that the routine use of amnioinfusion did not reduce the risk of MAS in infants born with meconium staining.33 Further research is still needed to resolve the uncertainties of this intervention. Routine intrapartum suctioning for infants born with meconium staining is no longer advised following current research recommendations.34 Additionally, no clinical studies warrant suctioning on the basis of meconium consistency alone.34 National evidence-based guidelines are continuously under review regarding the management of meconium-exposed infants. In regard to endotracheal suctioning in the delivery room, the most recent guidelines state that for a vigorous infant (i.e., normal respiratory effort and muscle tone), a bulb syringe may be used to clear secretions while receiving initial newborn care. For non-vigorous infants (i.e., depressed respiratory effort or muscle tone), place the infant on the radiant warmer, clear the secretions with a bulb syringe, and proceed with newborn resuscitation. Mechanical ventilation is required by nearly 30% of infants diagnosed with MAS.35,36 Optimal ventilator parameters, including minimal mean airway pressure, short inspiratory times, and maintained oxygen saturations, are essential to provide acceptable oxygenation and ventilation.35,36 Minimal stimulation handling, sedation, and ABG monitoring may be necessary for clinical improvement.35,36 While conventional ventilation is typically used as an initial management technique, high-frequency ventilation (HFV) is an alternative effective therapy. HFV aimed at lessening barotrauma, increasing secretion mobilization, and maintaining respiratory alkalosis may be advantageous.35,36 Surfactant

637

638

CHAPTER 24  Neonatal and Pediatric Pulmonary Disorders therapy can be considered a treatment therapy of MAS because it is used as a detergent to remove meconium.37,38 Surfactant administration may reduce the severity of the disease, reduce the need for ECMO (i.e., extracorporeal membrane oxygenation) utilization, and decrease the length of hospital stay.37,38 If all other therapy options have been attempted, ECMO may be used. Note that although ECMO is effective in treating MAS, it is also correlated with high occurrences of poor neurologic outcomes.38 Clinical intervention selections should depend on the severity of the aspiration and the degree of hypoxia that presents.

Prognosis The prognosis of infants with MAS has drastically improved over the past several years. In the United States, a retrospective analysis study revealed the overall mortality rate for MAS to be at a little over 1%.29,39 Some infants experience an increased prevalence of respiratory infections as a result of lung recovery.29,39 Survivors of MAS may develop chronic lung disease, including BPD, from clinical interventions.29,39 Chronic hypoxia, owing to meconium staining, may cause long-term neurologic deficits, including CNS damage, seizures, mental retardation, and cerebral palsy.29,39 New delivery room care techniques, as well as careful

management of resuscitative measures, have allowed for a better quality of life outcomes.

Congenital Heart Defects A congenital heart defect (CHD) is a health abnormality, present at birth, with the structure of the heart. Some defects can cause an array of difficulties in the care and management of the patient, while others are simple and do not need treatment. Many different structural defects can ultimately lead to the diagnosis of congenital heart disease. Heart defects can be divided into classes, acyanotic and cyanotic defects.40,41 If a defect does not influence oxygen in the body, it is called acyanotic, whereas a defect that reduces the amount of oxygen in the body is called cyanotic. More specifically, acyanotic heart defects refer to heart problems that do not normally interfere with the amount of oxygen or blood that reaches the body’s tissues.40,41 Acyanotic heart defects do not usually cause cyanosis. Acyanotic heart defects include septal wall defects, aortic and pulmonic stenosis, double aortic arch, and coarctation of the aorta40,42,43 (Table 24-1 and Figures 24-5 to 24-11). Cyanotic heart defects refer to heart issues that allow for the mixture of oxygen-rich blood and oxygen-poor blood.40,41 Cyanotic heart defects result in the development of cyanosis and include

TABLE 24-1 Acyanotic CHDs40,42,43 Type

Signs/Symptoms

Epidemiology

Pathophysiology

Risk Factors

Atrial septal defects51,52

• Shortness of breath • Fatigue • Heart palpitations/ murmur • Swelling

• 10% of all CHDs • 2:1 female-to-male ratio

• Freshly oxygenated blood from left atrium mixes with deoxygenated blood of right atrium and is pumped to the lungs • Increases blood volume to the lungs • Overworks right side of the heart, enlarging and weakening

• • • •

Ventricular septal defects53–55

• Failure to thrive • Tachypnea • Fatigue

• 2–7% of live births • More common in females

• Septum between the ventricles fails to form • Oxygenated blood mixes with deoxygenated blood • Heart must work harder to provide oxygen to body tissues

• Genetics • Hereditary

Atrioventricular septal defects56,57

• • • • •

• 3–5% prevalence • No variance in sex or race

• Oxygen-rich and oxygenpoor blood mix through the hole in the ventricles • Only one large valve between upper and lower heart chambers • Blood leaks into ventricles • Overworks and enlarges the heart

• Down syndrome • Smoking/drinking during pregnancy • Poorly controlled maternal diabetes • Rubella infection

Tachypnea Wheezing Tachycardia Cyanosis Lack of appetite; poor weight gain

Rubella infection Drug/alcohol use Maternal diabetes Maternal obesity

Neonatal

Type

Signs/Symptoms

Epidemiology

Pathophysiology

Risk Factors

Aortic stenosis58–60

• Chest pain • Dyspnea • Syncope

• 6% of CHDs • Severe aortic stenosis rare • Obstruction at aortic valve most common

• Aortic valve cusps defective/too thick/ improper separation • Outflow obstruction

• Rheumatic fever • Older maternal age • Infections

Pulmonic stenosis60,61

• • • • •

• 10% of CHDs • Female predominance

• Pulmonary valve cusps defective/too thick/ improper separation • Blood flow restricted

• • • •

Double aortic arch62,63

• Stridor • Apneic episodes • Difficulty swallowing

• Unknown

• Multiple arches on aorta present at birth • Arches compress trachea and esophagus

• Genetics

Coarctation of the aorta64,65

• • • •

• 4–6% of CHDs • Male predominance

• Narrowing of the aorta • Heart must pump harder to force blood through narrowed part

• Bicuspid aortic valve • Patent ductus arteriosus • Septal wall defects • Valve stenosis • Valve regurgitation

Type

Complications

Diagnosis

Treatment

Prognosis

Atrial septal defects

• • • •

Pulmonary hypertension Right-sided heart failure Heart arrhythmias Stroke

• • • •

Echocardiogram CXR ECG Cardiac catheterization

• Medical monitoring • Beta-blockers and anticoagulants • Open-heart surgery • Cardiac catheterization

• Excellent prognosis • Repair of atrial septal defect (ASD) improves prognosis

Ventricular septal defects

• Heart failure • Pulmonary hypertension Endocarditis

• • • •

Echocardiogram CXR ECG Cardiac catheterization • Pulse oximetry

• Surgical repair • Cardiac catheterization • Lasix and beta-blockers

• Medical therapy shows decrease in shunting

Atrioventricular septal defects

• Heart enlargement • Pulmonary hypertension • Recurrent respiratory tract infections • Heart failure

• • • •

Echocardiogram CXR ECG Cardiac catheterization

• Surgery

• Develops more rapidly than other CHDs • Prognosis poor without surgery

Aortic stenosis

• • • •

• • • •

Echocardiogram ECG CXR Cardiac catheterization

• Aortic valve repair • Balloon valvuloplasty • Aortic valve replacement

• Active, healthy following surgery

Pulmonic stenosis

• Infection • Right ventricular hypertrophy • Heart failure • Arrhythmias

• Echocardiogram • ECG • Cardiac catheterization

• Balloon valvuloplasty • Open-heart surgery

• Treatment highly successful

Double aortic arch

• Upper airway obstruction • Swallowing difficulties • Tracheal or esophageal damage

• Barium esophagography • Echocardiogram • ECG • CXR • Cardiac catheterization

• Supportive care • Surgical repair • Cardiac catheterization

• Excellent long-term prognosis • Persistent respiratory symptoms

Coarctation of the aorta

• • • • •

• • • •

• Surgery • Balloon angioplasty and stenting • Medications

• Guarded prognosis • Follow-up monitoring/ care imperative

Heart murmur Fatigue Shortness of breath Chest pain Fainting

Cyanosis Heavy sweating Difficulty breathing Difficulty eating

Heart failure Blood clots Arrhythmias Infections

Aortic stenosis Hypertension Aneurysm Heart failure Premature coronary artery disease

Echocardiogram CXR ECG Cardiac catheterization

Carcinoid syndrome Rheumatic fever Noonan syndrome Pulmonary valve replacement

639

640

CHAPTER 24  Neonatal and Pediatric Pulmonary Disorders

AO AO

PA LA

PA

RA

LA

LV RV

Aortic valve stenosis

RA

LV FIGURE 24-5  Atrial septal defect. AO, aorta; LA, left atrium; LV, left

ventricle; PA, pulmonary artery; RA, right atrium; RV, right ventricle.

RV

Normal open aortic valve

Aortic stenosis open aortic valve

AO PA LA

RA

FIGURE 24-8  Aortic stenosis.

LV RV

VSD

FIGURE 24-6  Ventricular septal defect (VSD).

AO PA

LA

RA

Common valve

Normal open pulmonary valve

LV RV

FIGURE 24-7  Atrioventricular septal defect.

FIGURE 24-9  Pulmonic stenosis.

Pulmonary stenosis open pulmonary valve

Neonatal total anomalous pulmonary venous return, truncus arteriosus, transposition of the great arteries, hypoplastic left heart syndrome, Ebstein anomaly, pulmonary atresia and tetralogy of Fallot40,42,43 (Table 24-2

Trachea

and Figures 24-12 to 24-18). A comprehension of fetal development is essential for properly detecting these abnormalities, understanding their pathophysiology, and planning treatment options.

Esophagus

FIGURE 24-11  Coarctation of the aorta.

FIGURE 24-10  Double aortic arch.

TABLE 24-2 Cyanotic CHDs40,42,43 Type

Signs/Symptoms

Epidemiology

Pathophysiology

Risk Factors

Total anomalous pulmonary venous return66

• Heart murmur • Cyanosis • Tachypnea

• 1% of CHDs • Male predominance (3:1)

• Pulmonary veins attach to the heart incorrectly • Oxygen-rich blood returns to the right atrium, mixing with oxygen-poor blood • Less oxygen-filled blood flows to the body, causing cyanosis

• Hereditary • Genetics

Truncus arteriosus67,68

• • • • •

Cyanosis Poor feeding/growth Sleepiness Dyspnea Tachypnea

• 1–2% of CHDs • No variance in sex or race

• One large blood vessel leads out of the heart • Creates severe circulatory problems

• Viral illness during pregnancy • Poorly controlled diabetes • Chromosomal disorders • Smoking during pregnancy

Transposition of the great arteries69,70

• • • •

Cyanosis Shortness of breath Lack of appetite Poor weight gain

• 5–7% of CHDs • 70% male predominance

• Position of the pulmonary artery and aorta are switched • Circulation of oxygenpoor blood through body; cyanosis

• Rubella • Poor maternal nutrition • Alcohol use during pregnancy • Down syndrome • Older maternal age

Hypoplastic left heart syndrome71,72

• • • • •

Cyanosis Tachypnea Cold extremities Fatigue Poor feeding

• >1.5% of all CHDs • 70% male predominance

• Left ventricle is too small/may not exist • Left-sided heart valves do not work properly • Aorta smaller than normal

• Family history • Genetics

(Continues)

641

642

CHAPTER 24  Neonatal and Pediatric Pulmonary Disorders

TABLE 24-2 Cyanotic CHDs40,42,43 (Continued) Type

Signs/Symptoms

Epidemiology

Pathophysiology

Risk Factors

Ebstein anomaly73

• • • •

Shortness of breath Fatigue Arrhythmias Cyanosis

• 0.5% of CHDs • Misdiagnosis rate high

• Tricuspid valve sits lower than normal in right ventricle • Portion of right ventricle becomes atrialized, causing a larger-than-usual right atrium • Right ventricle does not work properly

• Maternal exposure to lithium • Family history • Genetics

Pulmonary atresia74

• • • • •

Cyanosis Tachypnea Fatigue Feeding problems Clammy skin

• ~3% of CHDs • Male predominance

• Pulmonary valve does not form correctly • Solid sheet of tissue forms • Blood cannot travel normal route to lungs

• Rubella • Family history • Alcohol use/smoking during pregnancy • Down syndrome

Tetralogy of Fallot75–77

• • • • • • •

Cyanosis Dyspnea Fainting Clubbing Poor weight gain Fatigue Heart murmur

• 10% of CHDs • More common in males

• Combination of four defects • Oxygen-poor blood flows to rest of the body; cyanosis

• • • • • •

Type

Complications

Diagnosis

Treatment

Prognosis

Total anomalous pulmonary venous return

• • • • •

Enlarged heart Pulmonary hypertension Respiratory failure Heart failure Enlarged liver

• Echocardiogram • ECG • CXR

• Surgery

• Following surgery, grow and develop normally

Truncus arteriosus

• • • •

Respiratory problems Pulmonary hypertension Cardiomegaly Heart failure

• Echocardiogram • CXR

• Diuretics and inotropic agents • Surgical procedures • Cardiac catheterization

• Increasing survival rate

Transposition of the great arteries

• Hypoxia • Heart failure • Lung damage

• • • •

• Vasodilators • Atrial septostomy • Surgery

• Prognosis depends on therapy used

Hypoplastic left heart syndrome

• Arrhythmias • Edema • Developmental problems • Pulmonary embolism/ stroke

• Echocardiogram

• • • • •

• 60% 1-year survival

Ebstein anomaly

• Heart failure • Arrhythmias • Cardiac arrest

• • • •

Echocardiogram ECG CXR Cardiac magnetic resonance imaging (MRI) • Cardiac catheterization

• Regular monitoring • Beta-blockers and diuretics • Surgery • Radiofrequency catheter ablation • Heart transplant

• Depends on severity of anomaly

Pulmonary atresia

• Infectious endocarditis • Death if untreated

• • • •

Echocardiogram CXR ECG Cardiac catheterization

• Vasodilators • Stent placement • Radiofrequency catheter ablation • Heart surgery

• Critical CHD • Varies per child • Worst prognosis of CHDs

Tetralogy of Fallot

• Infectious endocarditis • Disability • Death

• • • •

Echocardiogram CXR ECG Cardiac catheterization

• Temporary surgery • Intracardiac repair

• Critical CHD • 50% 1-year survival • Worst prognosis of CHDs

Echocardiogram CXR ECG Cardiac catheterization

Vasodilators Fluid support Atrial septostomy Surgery Heart transplant

Rubella Alcoholism Family history Genetics Poor maternal nutrition Older maternal age

Neonatal

Vertical vein

AO

SVC

Common pulmonary vein Left pulmonary veins

PA

Right pulmonary veins

Patent ductus arteriosus

LA

PA Atrial septal defect

LA Mitral valve closed

RA

RA

LV

LV RV

RV IVC

FIGURE 24-12  Total anomalous pulmonary venous return.

FIGURE 24-15  Hypoplastic left heart syndrome.

IVC, inferior vena cava; SVC, superior vena cava.

© Mayo Foundation for Medical Education and Research. All rights reserved.

AO

PA AO

LA

Atrial septal defect

PA

RA Atrial septal defect

LV

LA

RA

RV LV Displaced tricuspid valve allows blood back into right atrium

RV

FIGURE 24-16  Ebstein anomaly.

Ventricular septal defect

FIGURE 24-13  Truncus arteriosus.

AO

PA

Transposed aorta and pulmonary artery

AO LA

PA RA

LA Atretic pulmonary valve

RA

LV RV

LV RV

Small (hypoplastic) right ventricle

FIGURE 24-14  Transposition of the great arteries.

FIGURE 24-17  Pulmonary atresia. © Mayo Foundation for Medical Education and Research. All rights reserved.

643

644

CHAPTER 24  Neonatal and Pediatric Pulmonary Disorders

Increased outflow in aorta

AO

Partial obstruction (stenosis) of right ventricular outflow (to lungs) and pulmonary valve

PA LA RA

RV

Thickened right ventricle (hypertrophy)

LV

Ventricular septal defect

FIGURE 24-18  Tetralogy of Fallot.

Clinical Signs and Symptoms Severe CHDs are evident before birth or during the first few weeks of life. Signs and symptoms may include cyanosis, tachypnea, swelling in the legs, abdomen, or areas around the eyes, as well as dyspnea during feedings, resulting in minimal weight gain.44 If the patient is asymptomatic at birth, less serious CHDs may not be diagnosed until later in childhood. Signs and symptoms apparent in older children could include easily dyspneic or fatigued during exercise, fainting spells, in addition to swelling in the hands, ankles, or feet.44 Additional CHD signs that may be detected during a patient assessment or diagnostic test include arrhythmias, heart murmurs, or even a weak pulse.44 Consider more conclusive diagnostic testing if any of these symptoms occur.

Etiology CHDs are generally caused by an irregular formation of the heart during fetal growth.45 Literature has shown that in most cases, there is no distinguishable cause for the development of a CHD.45 However, there are several risk factors, usually genetic and environmental, that are generally considered to cause the condition (see the “Risk Factors” section).

Epidemiology CHDs account for nearly one-third of all major congenital abnormalities.46,47 CHDs are common in children, with approximately 8 cases per 1,000 live births every year.46,47 See Tables 24-1 and 24-2 for statistics on specific CHDs.

Pathology/Pathophysiology By the fourth week of development, the heart begins taking shape and starts efficiently pumping

blood.42,43,48 During this critical time, the major blood vessels begin to form. It is at this point that deviations in cardiac development occur leading to CHDs. There are many different types of CHDs, which are defined by specific clinical characteristics (Tables 24-1 and 24-2). In certain cases, septal wall defects (i.e., holes) can form between heart chambers or major blood vessels.43 These holes allow the mixing of oxygenated and deoxygenated blood to occur, resulting in adverse effects to cardiac output or tissue oxygenation.43 Depending on the severity of the hole, lack of sufficient oxygen can cause cyanosis or perhaps lead to congestive heart failure (CHF).43 The three types of septal wall defects include ASDs, ventricular septal defects, and atrioventricular septal defects.43 Atrial septal defects occur when there is an opening in the intra-atrial septum (i.e., upper heart chamber walls)49,50 (Figure 24-5). A ventricular septal defect is a hole between the right and left ventricles (i.e., lower heart chamber walls)51–53 (Figure 24-6). An atrioventricular septal defect is a condition in which there are holes between the heart chambers and the valves of the heart (i.e., hole in the center of the heart)54,55 (Figure 24-7). Additionally, patent ductus arteriosus is an opening between two blood vessels (e.g., pulmonary artery and aorta) in the heart.54,55 Another type of CHD is characterized by obstructed blood flow. Aortic and pulmonic stenosis is defined by a discrete narrowing of the heart valves or blood vessels, resulting in an increased exertion of the heart to pump blood56–59 (Figures 24-8 and 24-9). Eventually, these obstructions can lead to cardiomegaly or cardiomyopathy.56–59 Several CHDs occur due to abnormal blood vessels. A defect called double aortic arch takes place when an arch fails to remodel and two aortic arches form a complete vascular ring, causing compression of both the trachea and the esophagus60,61 (Figure 24-10). Coarctation of the aorta is a discrete narrowing of the large blood vessel (i.e., descending aorta) leading from the heart62,63 (Figure 24-11). Total anomalous pulmonary venous return is a CHD that occurs when the four pulmonary veins attach to incorrect areas of the heart64 (Figure 24-12). In other words, there is no joining between the pulmonary vein confluence (i.e., coming together of the pulmonary veins) and the left atrium.64 Truncus arteriosus is a condition in which a single blood vessel leaves the heart, instead of the normal two vessels (i.e., pulmonary artery and aorta), and supplies both the systemic and the pulmonary circulation65,66 (Figure 24-13). Lastly, a CHD called transposition of the great arteries happens when the pulmonary artery and the aorta are on the wrong sides of the heart so that the pulmonary artery develops from the left ventricle and the aorta develops from the right ventricle67,68 (Figure 24-14). An underdeveloped heart illustrates another type of CHD. In hypoplastic

Neonatal left heart syndrome, the left side of the heart is too immature to effectively pump blood to the body69,70 (Figure 24-15). An additional type of CHD is characterized by heart valve abnormalities. In Ebstein anomaly, the tricuspid valve is malformed, displaced, and oftentimes does not work properly71 (Figure 24-16). Pulmonary atresia is also a heart valve disorder wherein the pulmonary valve is missing, triggering unusual blood flow to the lungs72 (Figure 24-17). Finally, some infants are born with numerous heart defects. Tetralogy of Fallot is the most common cyanotic CHD and is a combination of a ventricular septal defect, pulmonic stenosis, a misplaced aorta, and right ventricular hypertrophy (i.e., thickened ventricular walls)73–75 (Figure 24-18).

Risk Factors Most CHDs are a result of in utero heart development complications, the cause of which is typically unknown. However, there are several environmental and genetic risk factors that may play a role. Environmental factors, including maternal rubella, gestational diabetes, certain medications, alcohol consumption, and maternal smoking, have all shown to adversely affect heart development.47 Medications known to increase the risk of CHDs include thalidomide, angiotensinconverting enzyme (ACE) inhibitors, statins, antiseizure medicines, and lithium.47 Family history can also play a role in producing a CHD. Some heart defects have autosomal-dominant inheritance, meaning that a parent with a defect has a 50% chance of passing the condition on to their newborn.47 Research has also shown that some types of CHDs can be directly related to chromosome abnormalities or single gene disorders.47 Genetic testing can help to detect these fetal development disorders that are associated with an increased risk for CHDs.

Complications Specific complications depend on the type and severity of the particular CHD. There are several conditions that can develop as complications of CHDs, including endocarditis, developmental delays, pulmonary hypertension, CHF, and stroke.76 Clinicians should discuss with family members ways to minimize the risk for complications due to CHDs.

Diagnostic Testing The identification of CHDs is often made before birth and is commonly detected via fetal ultrasonography.77 Prompt diagnosis of CHDs allows for thorough monitoring as well as proper planning prior to delivery. Delivery of these infants should ideally be performed at facilities with dedicated cardiac ICUs and

experienced ECMO programs. For those infants not diagnosed in utero, many diagnostic techniques exist to clarify the type, location, and severity of the heart defect. These tools include ECGs, CXRs, cardiac catheterization, echocardiogram, cardiac auscultation, and Doppler ultrasound (US).78

Treatment and Management Management of CHDs is mostly supportive; however, that does not diminish the significance of the clinician’s role. Proper oxygenation and ventilation management can significantly impact the cardiovascular system and assist in avoiding further complications. Additionally, hemodynamic imbalances must be appropriately monitored as they can cause cardiac abnormalities, poor tissue perfusion, or even cardiac arrest and are detrimental to the infant’s prognosis.79,80 Recognition of patient deterioration and cautious clinical assessment can play a substantial role in proper CHD treatment and management. As mentioned previously, some CHDs have no long-term consequences and may safely go untreated. Certain defects may even correct themselves as the patient ages. However, others are very serious and require treatment soon after diagnosis. Treatment decisions will depend on the type and severity of the defect. Options may include cardiac catheterization, open-heart surgery, or heart transplant.79,80 Procedures using catheterization allow repairs to be done (e.g., fix holes or increase areas of narrowing) without surgically opening the heart. For milder defects, especially those found later in life, certain medications could help to make the heart function more efficiently. ACE inhibitors, angiotensin II receptor blockers, and betablockers are drugs that alleviate strain on the heart by decreasing blood pressure, heart rate, and fluid retention.79,80 Additionally, some medications can help with arrhythmias. In some cases, a combination of treatment modalities is required. Additionally, some procedures may need to be done in phases, over an extent of time, while others may need to be repeated as the patient ages.79,80 Some infants with CHDs may require long-term treatment throughout their lifetime. While outcomes for infants with CHD have improved drastically, most patients will require lifelong monitoring and treatment. Follow-up cardiology appointments, exercise restrictions, and infection prevention will aid in letting infants with CHD grow up to lead healthy lives.79,80

Prognosis Infants diagnosed with CHDs should continue to receive routine exams throughout their lifetime to reduce the risk of heart disease. Furthermore, undetectable CHD have the potential to cause disabilities later in life.

645

646

CHAPTER 24  Neonatal and Pediatric Pulmonary Disorders

Infant Respiratory Distress Syndrome neonatal respiratory distress syndrome, and previously called hyaline membrane disease, almost exclusively affects premature infants with immature lung development81–84 (Figure 24-19). It is a neonatal condition caused by an insufficient development of pulmonary surfactant and lung structure immaturity.85 The occurrence and severity of IRDS are inversely related to the gestational age of the newborn.84,86 Immense strides in research, clinical practice, and education have been made to better understand the pathophysiology and management of IRDS, leading to improvements in morbidity and mortality rates.

including A, B, C, and D.89 Surfactant deficiency is one of the principal causes of respiratory distress in premature infants. Generally, alveolar type II cells synthesize and store surfactant starting at 16 weeks’ gestation.89 Between weeks 28 and 38 of gestation, surfactant is secreted into the alveoli and transfers into the amniotic fluid.89 The genes involved in surfactant enhancement include surfactant protein B (SP-B) gene, surfactant protein C (SP-C) gene, and the ABCA3 gene.90,91 All are critical for surfactant production and proper function of the infant lung.90 Therefore, infants born prior to 28 weeks’ gestation may potentially have underdeveloped lung structures with little or no surfactant production, leading to IRDS susceptibility.91

Clinical Signs and Symptoms

Epidemiology

The clinical characteristics of IRDS are consistent with the infant’s maturity. Signs of surfactant deficiency and increased chest wall compliance are highly depicted in this patient. Progressive symptoms of respiratory distress begin immediately after birth and include tachypnea, expiratory grunting, intercostal and subcostal retractions (i.e., “seesaw” pattern), cyanosis, and nasal flaring.87,88 Extremely premature infants look distressed and may develop apnea events, causing eventual unresponsiveness.87,88 Chest auscultation features decrease breath sounds.87,88

Approximately 5,000 infants are born with IRDS each year.86 The risk of developing IRDS depends on gestational age. That is, the closer to term a newborn is, the less likely the risk of IRDS. The incidence of IRDS is 10% in all-preterm infants, with 60% of those infants being less than 28 weeks’ gestational age.83 Despite clinical advancements, the mortality rates for infants with respiratory distress syndrome (RDS) is still reaching nearly 10%, making it the fifth leading cause of death in infants under 1 year of age.83 IRDS does not affect sex and race equally. Males are more often affected than females.92 Additionally, the Caucasian race historically has a higher incidence of RDS than others.93

Infant respiratory distress syndrome (IRDS), also known

Etiology IRDS develops in premature infants because of impaired surfactant synthesis, resulting in insufficient amounts of surfactant, leading to adverse effects, including atelectasis, V/Q mismatch, and hypoventilation.89 Surfactant is a mixture of lipids and proteins that reduces surface tension at the alveolar interface in the lung. It is composed of phospholipids and four surfactant proteins,

Pathology/Pathophysiology Poor gas exchange, increased chest wall compliance, thickened alveolar–capillary (A–C) membranes, inadequate vascular processes, and deprived lung fluid clearance are all pathophysiologic means that contribute to the clinical picture of an IRDS preterm infant.89

Normal alveoli

Airway Lung

FIGURE 24-19  Characteristics of immature lung development.

Collapsed alveoli

Neonatal The etiological significance of surfactant deficiency as well as the immature vascular development and abnormal surface tension components all impact IRDS disease progression89 (Figure 24-20). This disturbance of normal surfactant transformation has been identified in the neonatal population as a cause of respiratory distress.90 Surfactant dysfunction in the form of abnormal surfactant quantity, composition, metabolism, and inactivation of surfactant has been described in several infant acute lung injuries, including IRDS.91 Decreases, increases, and no changes in surfactant quantity have all been described.91 These inconsistent fluctuations in surfactant can lead to interstitial edema, hyaline membrane formation, and pulmonary hypertension as a result of both respiratory and metabolic acidosis.90 Furthermore, the onset of pulmonary hypertension can lead to the shunting of blood (as much as 80% of the cardiac output), which can cause greater hypoxemia problems for the infant.89 This vicious cycle can continue and may even lead to further pathophysiologic suppression. Clinicians must remember that not only these infants have immature lungs, but prematurity also puts them at risk for both metabolic and cardiac challenges.

Risk Factors Prematurity is the greatest risk factor for IRDS. Additional risk factors include maternal diabetes, cesarean delivery, and asphyxia.94

Complications Complications related to IRDS can significantly influence morbidity outcomes. Some of the complications impacting these premature infants include septicemia (i.e., blood poisoning), bronchopulmonary dysplasia (BPD), pulmonary hemorrhage, hypertension, NEC, and susceptibility to other respiratory disorders.95 An interruption in regular growth patterns, also known as failure to thrive, significantly impacts infants with RDS and is perhaps the leading contributor to worldwide childhood morbidity and mortality.95 Increased work of breathing, decreased lung compliance, and recurring oxygen desaturations are also commonly seen in pulmonary tests (PFT) of premature infants surviving IRDS.95 Future focuses on immunologic processes and chronic pathologies related to IRDS will assist in improving the outcomes of these patients.

Prematurity

Surfactant deficiency

Atelactasis

V/Q mismatch ACUTE

Immature lung

Hypoventilation

Hypoxemia & Hypercarbia

CHRONIC

High FiO2 & Baro or volutrauma

Respiratory & metabolic acidosis Infections Pulmonary vasoconstriction

Injury to endothelial and epithelial cells

Proteinaceous exudate

RDS

FIGURE 24-20  Pathogenesis of IRDS versus BPD. Modified from http://flipper.diff.org/app/items/info/6229.

Reperfusion

Inflammatory cell influx

Antioxidant reduction

Cytokine release

Free-radical reactions

Lung Injury

BPD

647

648

CHAPTER 24  Neonatal and Pediatric Pulmonary Disorders

Diagnostic Testing IRDS may coexist with a multitude of conditions and therefore complicate diagnostic approach considerations. Clinicians should base their diagnosis on the history, patient assessment, CXR, and laboratory evaluation. Infants at risk for IRDS should be evaluated using fetal lung maturity tests. The amniotic fluid lecithin-tosphingomyelin (L:S) ratio test is a marker of fetal lung maturity. Lecithin is the most common phospholipid in surfactant. Typically, there is twice as much lecithin as sphingomyelin; thus, an L:S ratio of greater than 2:1 depicts a mature lung.96 Additionally, an increased level of phosphatidylglycerol (PG), the second most common phospholipid in surfactant, near term indicates a low risk for IRDS.96 The presence of PG and an L:S ratio greater than 2:1 drop the risk of IRDS to nearly 0%.96 Blood gas analysis typically shows moderate-to-severe hypoxemia, varying levels of hypercapnia, and mixed respiratory and metabolic acidosis.86 Respiratory acidosis is primarily due to alveolar atelectasis and overdistension. On the other hand, metabolic acidosis occurs because of lactic acid accumulation (i.e., poor tissue perfusion and anaerobic metabolism). CXR of infants with IRDS reveal diffuse, bilateral, ground-glass appearances, air bronchograms, and reduced lung expansion86 (Figure 24-21). Also, the heart may be normal or slightly enlarged.86 Using radiographic findings, IRDS can be described as stages and is generally correlated with disease severity and progression. In the early stages (stage 1), air bronchograms are absent and alveolar atelectasis targets the dependent areas of the lungs.86 In

FIGURE 24-21  CXR of IRDS. Reproduced from Parenchymal lung disease. Auckland District Health Board. http://www .adhb.govt.nz/newborn/TeachingResources/Radiology/LungParenchyma.htm.

infants with mild-to-moderate IRDS (stages 2 and 3), the CXR reveals overdistension, the presence of air bronchograms, and an increase in dense opacities.86 As IRDS progresses (stage 4), large areas of increased lung opacity (i.e., “white out”), uniform atelectasis, and air bronchograms can be seen on the radiograph.86 When IRDS is characterized by excess fluid (e.g., pulmonary edema), fluid input and output must be closely monitored. While infrequently used to date, a recent study has reported the accurate and reliable use of lung US in diagnosing IRDS.86 Ultrasonography can be used to find lung consolidations and even diagnose or exclude a coinciding pleural effusion.86 Other monitoring devices, including end-tidal CO2, cardiopulmonary displays, and Doppler flow studies, can be used to monitor patient progress.

Treatment and Management Due to the complexity of IRDS, the preferred treatment should always be prevention. If predictive tests (L:S ratio, PG levels) indicate a high IRDS risk, elective cesarean delivery should be stopped and premature delivery should be delayed.96 The administration of antenatal corticosteroid therapy prior to delivery may accelerate lung development and reduce the risk of respiratory distress.97 However, a recent study concluded that multiple courses of antenatal corticosteroids did not improve results and were associated with decreases in neonatal weight at birth.97 Because research results remain unclear, clinical judgment must be used when deciding on repeat doses of administered corticosteroids for preterm delivery. The arrival of surfactant replacement therapy has reduced morbidity and mortality rates in infants with IRDS by nearly 50%.98 Studies have found that early surfactant therapy reduces the occurrence of pulmonary air leaks as well as the severity of the chronic lung disease.98 Another clinical trial targeting intubated IRDS patients showed that early surfactant therapy combined with rapid extubation to nasal CPAP (nCPAP) decreased the need for and duration of mechanical ventilation.99 Surfactant replacement therapy has the ability to improve survival and lung development outcomes in these preterm infants. Oxygen therapy as a treatment modality for IRDS is administered via an oxygen hood, nasal cannula, or isolette to the infant.99 Providing adequate oxygenation, preventing atelectasis, and reducing risk factors for IRDS are the main features of this therapy option. When applying oxygen therapy, substantial efforts must be made to minimize Fio2 levels to no more than what is necessary to prevent potential lung damage. Oxygen therapy was the principal therapeutic modality for IRDS before the introduction of CPAP. If oxygenation fails to improve with basic oxygen therapy, CPAP should be started. CPAP has the ability to keep the alveoli open at the

Neonatal end of expiration, therefore decreasing the opportunity for shunts.99 Studies have shown that early nCPAP can reduce the need for mechanical ventilation later on.99 With the ability of CPAP to stabilize the alveoli, surfactant production is allowed to continue without interference. Heated and humidified HFNC therapy is another respiratory support modality being used in infants with IRDS. This device allows for the delivery of 100% heated and humidified high-flow oxygen at body temperature.100 Some research has suggested that HFNC therapy may be a more effective, better-tolerated treatment method for IRDS.100 Evidence suggests fewer ventilator days, reduced nasal trauma, and improvements in weight gain when using HFNC therapy.100 However, further research is still required to determine the best methods for weaning as well as the long-term effects of neonatal treatments. Endotracheal intubation and mechanical ventilation may be indicated for a variety of reasons. Mechanical ventilation should be initiated in infants with IRDS when Fio2 or pressure requirements exceed safe thresholds, ABG results display increases in respiratory acidosis, or if prolonged apneic episodes persist.101 In the very preterm infants, mechanical ventilation may be needed immediately following delivery. For these delivery room cases, clinicians should use their patient care protocols and physical assessment skills to guide decision making. Mechanical ventilation may also be indicated in full-term infants if presenting with severe respiratory distress or asphyxia.101 Mechanical ventilation should be considered a physiologic support to the patient while they recover from IRDS. Additionally, HFV may be indicated in infants struggling while receiving conventional mechanical ventilation. An animal study demonstrated that HFV promoted uniformity in lung aeration, gas exchange improvements, and decreased lung inflammation in patients with IRDS.101 Nevertheless, HFV clinical trials are still awaiting evaluation of short-term and long-term patient outcomes.101 Hypothermia may further complicate IRDS. Clinicians must prevent hypothermia and care for these patients in a neutral thermal environment. Routine monitoring and consistent assessments are very useful in managing the daily abnormalities of these patients.

Prognosis Prognosis of preterm infants with IRDS has steadily improved. In the last 50 years, the mortality rate for IRDS has significantly decreased by almost 13%.102 If managed effectively, IRDS often gets worse following birth and will improve slowly over time. Acute clinical problems following diagnosis of IRDS include alveolar rupture, infections, AOP, and hemorrhaging.102 Bronchopulmonary dysplasia (BPD), ROP, and neurologic impairments are possible long-term clinical issues

following treatment and management of IRDS.102 Despite improved survival rates, oftentimes therapies (e.g., mechanical ventilation) needed to treat IRDS are the very reasons responsible for prolonged symptoms and altered lung development. The major long-term respiratory complication of RDS is BPD. Forthcoming alterations in pulmonary function tests (PFT) suggest the development of reactive airway disease in these patients as a result of BPD diagnosis.102 Fetal care improvements have led to better neonatal outcomes.

Bronchopulmonary Dysplasia BPD is the most common cause of respiratory insufficiency and ventilator dependence in infants born prematurely. BPD affects nearly 10,000–15,000 infants every year in the United States.103,104 It is a multifactorial syndrome that affects major organ systems within the body. BPD is defined as a clinical, radiographic, and pathologic disease process affecting premature infants with IRDS, exposed to aggressive ventilatory support and high levels of oxygen therapy.103,104 This long-term mechanical ventilation and supplemental oxygen requirements cause severe lung derangement resulting in poor prognoses. Because of this, infants with BPD have an increased risk of pulmonary morbidity and mortality within the first 2 years of life.103,104 Lung function impairment may persist throughout childhood and even into adulthood.103,104 The validity and utility of a commonly used definition for BPD remains questionable. A recent study compared three diagnostic criteria for defining BPD: the original 36-week threshold, the National Institutes of Health workshop definition, and the physiologic definition requiring a room air challenge.103,104 Conclusions stated that a contemporary definition of BPD, which correlates with respiratory morbidities in childhood, is still needed.105 A diagnostic criterion that clearly defines the pulmonary abnormalities of BPD is important to identify infants who have different severities of this lung disease.

Clinical Signs and Symptoms BPD usually presents with irregular findings on physical examination, CXR, PFT, and histopathologic exam. Infants born with BPD exhibit signs and symptoms similar to that of IRDS, including tachypnea, tachycardia, increased work of breathing (e.g., nasal flaring, retractions), and recurrent desaturations.106 BPD patients are usually very premature, have very low birth weight, and require significant respiratory support to maintain oxygenation and ventilation.106

Etiology BPD is often due to respiratory distress. As previously stated, IRDS is the result of lung development

649

650

CHAPTER 24  Neonatal and Pediatric Pulmonary Disorders complications. The insufficient production of surfactant occurs because of infant prematurity and prompts the need for ventilatory support in these patients.107 Invasive mechanical ventilation has the likelihood of causing lung damage and may result in the infant requiring prolonged support, and a BPD diagnosis. BPD may also arise from other adverse medical conditions, including congenital lung malformations, pneumonia, or even other infections.107 All of these BPD-associated illnesses can cause further lung inflammation and scarring to the patient. Genetic susceptibility has also recently been suggested to contribute to some cases of BPD; however, follow-up research is still needed to support these findings.107

Epidemiology The epidemiology of BPD has transformed over the years following the introduction of new, advanced therapies as well as a better clinical understanding of the disease progression. Today, severe BPD is less frequent and has been replaced by milder, more frequent forms as the survival of premature infants has strikingly increased.108 The most important determinant of BPD incidence is the degree of prematurity, with BPD largely occurring in infants less than 28 weeks’ gestational age or below 1,000 g birth weight.108 A recent report stated that the incidence of diagnosis of BPD had significantly decreased concurrently with improvements in BPD care protocols.108 Nowadays, BPD rarely occurs in infants greater than 30 weeks’ gestational age or with birth weights greater than 1,200 g.108 African American infants generally have a lower occurrence of BPD compared with Caucasians.108 Additionally, male premature infants with BPD tend to have worsening disease progression and outcomes. Noteworthy is the challenge in comparing BPD incidence as different patient classifications, criteria, and management strategies are frequently used.

Pathology/Pathophysiology Four distinct pathologic findings of BPD are generally described: acute lung injury, exudative bronchiolitis, proliferative bronchiolitis, and obliterative fibroproliferative bronchiolitis.109 The pathology of BPD is complex, and clinicians must be able to recognize the various factors that lead to lung injury in this patient population. Damage to alveolar, bronchial, or vascular development can result in significant dysfunction in infants with BPD. A thorough comprehension of the alveolar, bronchial, and vascular pathology will assist in providing optimal care to these preterm infants. Wilson-Mikity syndrome describes preterm infants presenting with respiratory distress soon after birth.109 Initially, these infants have diffuse lung infiltrates, tachypnea, and cyanosis.109 Over the course of weeks, some infants recover spontaneously while those who die exhibit hyperaeration and reduced

A–C membrane density.109 The classical description of BPD, defined by structural injury, is now commonly referred to as “old BPD.” “Old BPD” was described as developing in four pathologic stages based on days of life (DOL). In stage one, the first through third DOL, the appearance of BPD is the same as IRDS with not enough surfactant in the lungs.110–112 This stage of BPD involves the presence of widespread atelectasis, hyaline membranes, and air bronchograms.110–112 In stage two, the 4th through 10th DOL, lung destruction occurs. Hyaline membranes persist and alveoli begin to merge in a similar manner as emphysema.110–112 Stage three, the 10th through 20th DOL, involves progressive repair of the lung. Persistent injury results in air trapping, interstitial edema, and ciliary dysfunction.110–112 In stage four, more than 1 month of age, the CXR depicts emphysematous alveoli. This chronic lung damage causes pulmonary hypertension, fibrosis, and prolonged atelectasis.110–112 Recognizing any of these above stages could assist in the diagnosis of BPD. Presently, the “new BPD” defines BPD as a developmental delay. The key features of the “new BPD” pathology include alveolar hypoplasia, hindered A–C development, abnormal pulmonary vasculature, and increased interstitial fibrosis.113 It is believed that these features manifest as a result of subsequent changes in lung development following birth. While there are no causative links to “new BPD,” mechanical ventilation and oxygenation can still be justifying factors.

Risk Factors Multiple risk factors exist for the development of BPD. Premature infants with very low birth weights are often exceptionally susceptible to BPD because of their immature structural and functional respiratory system. Premature birth and subsequent events, including long-term oxygen exposure, prolonged mechanical ventilation, and infection, are the leading causes of lung development abnormalities and loss of gas exchange in BPD.114 Other risk factors include hypothermia or hypotension at admission, preeclampsia, or hypercarbia.114 Certain risk factors may increase the degree of BPD severity, including prolonged acidosis, patent ductus arteriosus, oligohydramnios, or an Apgar score of less than 6.114

Complications The complications associated with BPD are relatively unpredictable and can vary widely between individual patients. Acute complications include bronchiolitis, heart problems, and kidney difficulties.115 Long-term complications may involve respiratory infections, delayed growth, neurologic dysfunction, and coordination problems.115 Various degrees of obstructive lung disease may persist throughout the life span. For some, prolonged lung dysfunction will continue to be apparent in abnormalities, including airway hypersensitivity,

Neonatal wheezing, and emphysematous symptoms.115 Frequent rehospitalizations for respiratory exacerbations and infections may continue into adolescence and adulthood. These chronic health complications can also adversely impact the families of these babies.

Diagnostic Testing ABG analysis in BPD patients may disclose acidosis, hypercapnia, and hypoxia with mounting oxygen therapy requirements.116,117 End-tidal CO2 monitoring may be advantageous in recognizing trends, especially when correlated with ABG results.116,117 Continuous oxygenation monitoring may be required because of frequent desaturations. Changes in pulmonary mechanics, including increased airway resistance, decreased lung compliance, increases in functional residual capacity (FRC), and increased airway hyperresponsiveness, may all appear on PFT.116,117 Infants with BPD can develop pulmonary hypertension, increased pulmonary vascular resistance, or right ventricular hypertrophy.116,117 Echocardiograms are extremely valuable tools in diagnosing injury to the pulmonary circulation. BPD severity levels can be determined through the use of CXR. CXRs may show diminished lung volumes, atelectasis, pulmonary edema, or even PIE118 (Figure 24-22). Today, high-resolution imaging (computed tomography or MRI tests) can help detect irregularities not commonly seen on CXRs.

Treatment and Management In most cases of BPD, the focus of therapy is on prevention and routine treatment of IRDS. The foundation for treating IRDS includes minimal oxygen therapy use,

FIGURE 24-22  CXR of a patient with BPD. Reproduced from Semple T, Akhtar MR, Owens CM. (2017). Imaging bronchopulmonary dysplasia: a multimodality update. Front. Med. 4:88. doi: 10.3389/fmed.2017.00088.

surfactant replacement therapy, CPAP, and mechanical ventilation.119 Supplemental oxygen therapy is necessary to prevent tissue hypoxia; however, oxygen toxicity should always be avoided. Premature infants have a relatively deficient antioxidant defense and therefore are at an increased risk of injury due to oxygen free radicals.119 Ideal oxygen saturation strategies for infants at risk for BPD have not been clearly determined. However, many clinicians have adopted the consensus of targeting oxygen saturation ranges of 90–95% following the results of the Surfactant, Positive Pressure, and Pulse Oximetry Randomized Trial (SUPPORT) trial.119 Recall that surfactant dysfunction occurs in a high percentage of preterm infants requiring continued ventilatory support. While there is limited evidence regarding the usefulness of late surfactant therapy in infants with BPD, early surfactant administration has been associated with a lower incidence of disease progression.120 The use of “gentler ventilation,” described earlier as more aggressive CPAP and less-invasive techniques, may eliminate the need for advanced therapies and even decrease injury to the lungs.121,122 While positive pressure ventilation is necessary to recruit alveoli and prevent atelectasis in the immature lung, this treatment option is a targeted marker for the development of BPD. Early extubation and favorable use of noninvasive positive pressure ventilation (NIPPV) have the potential to reduce BPD severity likelihood.121 Many ventilator modes and strategies have been studied in the hopes of reducing impending lung injury. Some researchers have adopted the term volutrauma, suggesting the occurrence of lung injury in regard to low versus high tidal volume (VT) approaches.122 Results have been mixed when discussing which specific mode provides the most optimal use of conventional ventilation in regard to improved pulmonary outcomes.122 However, minimizing oxygen and volume in the lungs is promised to reduce the lung injury in BPD diagnoses. Generally, when ventilating infants with chronic lung injury, using adequate positive end-expiratory pressure levels, stabilizing atelectatic alveoli, avoiding overdistension, and targeting reduced tidal volume (VT) values have been shown to have clear benefits in managing BPD.122 Though HFV is an applicable lung-protective ventilatory strategy, most trials have not had large enough sample sizes or sufficient evidence to support its use. Regardless of the ventilatory strategy used, an increase in alveolar recruitment, avoidance of hypocapnia, and a decrease in BPD risk factors need to be the main focus. While several of these interventions are individually effective, ventilator bundle strategies have been shown to positively improve management of patients with BPD.122 BPD can be further complicated by pulmonary edema. Fluid restrictions and diuretics are often used to prevent excessive fluid administration and treat pulmonary edema.122 Other therapies suggested to manage BPD involve permissive hypercapnia (ventilation strategy that allows for un-physiologically

651

652

CHAPTER 24  Neonatal and Pediatric Pulmonary Disorders high partial pressure of carbon dioxide (Pco2) to permit lung-protective tidal volume values123), corticosteroids (group of hormones used to improve lung function and reduce inflammation124), mast cell stabilizers (block the release of mast cells, thereby preventing airway hyperreactivity125), antioxidants (enzymes that protect the lung and prevent deficiency of trace elements126), vitamin A (promotes gene regulation necessary for lung growth and increases surfactant production127), and inhaled nitric oxide (pulmonary vasodilator that improves gas exchange and reduces pulmonary vascular resistance); however, effectiveness varies and routine use is not commonly recommended128).

Prognosis Survival rates of the most preterm infants have drastically improved since the introduction of surfactant therapy.129,130 Advancements in technology and improved understanding of BPD pathophysiology have led to milder BPD disease progression today than in years past. Infants who develop severe BPD remain at risk for repeated hospital admissions throughout their life span.129,130 Irregular neurologic effects, muscular development, and long-term respiratory morbidity are common in infants with BPD.129,130

Transient Tachypnea of the Newborn Transient tachypnea of the newborn (TTN) is a lung

condition seen in infants shortly after delivery. Others have termed it “wet lungs” or “type II respiratory distress syndrome.”131,132 It is a disorder that describes mild neonatal respiratory problems, which begin after birth and last roughly 3 days.131,132 It is a self-limited illness (i.e., resolves spontaneously with or without treatment), typically correcting within 48–72 hours.131,132 TTN is caused by excessive lung fluid due to compromised clearance mechanisms.131,132 Signs of respiratory distress typically become evident within 6 hours of birth. At delivery, clinicians may have challenges distinguishing TTN from other causes of respiratory distress, including sepsis, aspiration, and pneumonia.131,132

Clinical Signs and Symptoms Attaining a full history and clinical assessment are crucial to the proper management of these infants. The maternal history in TTN consists of cesarean delivery or extremely rapid labor.133 Within the first few hours of life, tachypnea and signs of respiratory distress (e.g., nasal flaring, grunting, retractions, and cyanosis), increased oxygen requirements, and hypoxia without associated carbon dioxide retention characterize this disease.133 It is important for clinicians to observe these infants for signs of clinical deterioration, which may suggest the development of respiratory fatigue or another diagnosis. This disorder is again transient,

meaning clinical symptoms will usually resolve within 72 hours following birth.

Etiology TTN results from complications during the prenatal to postnatal transition period. Delayed absorption of fetal lung fluid following delivery causes TTN. The subsequent pulmonary edema is a common cause for respiratory distress in the immediate newborn. This development of fluid accumulation may provoke tachypnea, increased work of breathing, or reduced pulmonary compliance, especially in neonates.134,135

Epidemiology The exact incidence of TTN is weakly unknown, but publications have estimated that roughly 1% of newborns have some form of respiratory distress unrelated to infection.136,137 Of this 1%, nearly 30–50% have TTN.136,137 Despite being one of the most common causes of IRDS, many cases go underdiagnosed due to coexisting problems.136,137 While TTN is generally a self-resolving disorder, it has been correlated with subsequent morbidity.

Pathology/Pathophysiology TTN results in the admission of neonates to the NICU because of failure to clear fetal lung fluid prior to delivery. The ensuing respiratory distress is characterized by the retention of fluid in air spaces, resulting in alveolar hypoventilation.138,139 Typically at birth, the mature lung switches from fluid secretion to fluid absorption in response to traveling catecholamines and other hormones.138,139 The remaining fluid is routinely expelled during delivery. Reduced expression of chemical channels (e.g., Na+, Cl-) contributes to the inability of the immature fetal lung to switch from fluid secretion to fluid absorption.138,139 Several studies have demonstrated the critical physiologic importance of Na+ transport channels during delivery. Ineffective Na+ channels have the potential to cause respiratory distress in at-risk patients. Disruption of this process can lead to liquid filling the alveoli and moving into the interstitium.138,139 Mature newborns, especially infants delivered by cesarean section, are often deprived of these fluid clearance changes during labor, making the risk of excessive pulmonary fluid much more probable.138,139 Research has also suggested that low lamellar body counts derived from infant secretions, consistent with surfactant abnormalities, may be associated with TTN.138,139

Risk Factors The main risk factors for TTN include cesarean delivery, low gestational age, male gender, maternal history of asthma, macrosomia, and maternal diabetes.131,140 As more babies are being delivered by elective cesarean

Neonatal section before the onset of labor, the occurrence of respiratory distress due to failed transition has increased.131,140 Studies have also shown that gestational age is inversely proportional to TTN occurrence due to the adverse effects of prematurity factors.131,140 Likewise, research has found a potential connection between TTN and asthma, demonstrating that male infants of asthmatic mothers are more likely to develop TTN later in life.131,140 Additionally, neonates with TTN are at a higher risk for subsequent development of asthma.131,140 However, to date, no straightforward correlation with asthma and TTN can be made based on the existing literature.131,140

Complications Few potential complications exist. One study found neonatal problems and prematurity difficulties to be significantly increased in infants with TTN.141 Some infants may develop hypoxia, respiratory fatigue, and acidosis as a consequence of RDS.141 In infants with an increased work of breathing, air leaks may be occasionally seen.141 Careful monitoring for worsening respiratory distress should be performed.

Diagnostic Testing Most often, infants with TTN are hemodynamically stable, but an ABG assessment is essential to establish the degree of gas exchange as well as acid–base balance. A rising carbon dioxide level may indicate respiratory fatigue, impending respiratory failure, or even a pneumothorax.131 Clinicians should continuously monitor pulse oximetry for assessment of infant oxygenation. Pulse oximetry monitoring allows for oxygen-level adjustments needed to maintain adequate saturation in these patients. The diagnostic standard for TTN is CXR and is characterized by diffuse infiltrates, prominent perihilar streaking secondary to retained lung fluid, and small pleural effusions131 (Figure 24-23). Follow-up CXRs may be needed if the respiratory status worsens. The definitive diagnosis of TTN is often based on the

remedying of symptoms within a strict time frame (i.e., within 72 hours).131 Misdiagnosis of TTN occurs if symptoms remain beyond the 72-hour period. Additional patient evaluation and diagnostic testing must be done to determine the true cause of the respiratory distress. An echocardiogram may be necessary for patients with more than 5–6 days of persistent tachypnea to help exclude congenital cardiac defects.131

Treatment and Management Treatment and management of TTN is oftentimes in the form of supportive care in that the pulmonary system will improve as retained lung fluid is absorbed. Supportive care may include both intravenous fluids and NG feeding until the respiratory distress decreases enough to allow for oral feedings.131 Supplemental oxygen therapy, a state of thermal balance, and minimal stimulation are necessary for these patients.131 Repeat ABG assessments and CXRs should be performed if the infant’s status decompensates. Therapeutic care should be given on an as-needed basis for developing hypoglycemia, hypothermia, or sepsis, all risk factors associated with TTN.131 Additionally, several studies have evaluated the use of antenatal corticosteroids (e.g., dexamethasone) as a management option for fetal lung immaturity and reduced expression of chemical channels. Results demonstrate a decreased incidence of pulmonary adverse outcomes and the greatest impact of exposure in the reduction of respiratory morbidity in TTN.142 Following resolution of TTN, the clinical focus needs to be on routine newborn management.

Prognosis Prognosis is excellent for infants with TTN. Recall that TTN is a self-limiting disease and thus rarely causes long-term morbidity and mortality. One study looked at TTN characteristics as risk factors for childhood asthma. Conclusions revealed that infants with TTN are at an increased risk for asthma-related hospitalizations during the toddler years.143,144 Additionally, infants with

FIGURE 24-23  CXR of TTN with perihilar streaking. Reproduced with permission from Transient Tachypnea of the Newborn Lokesh Guglani, Satyan Lakshminrusimha, Rita M. Ryan. Pediatrics in Review. 2008; 29(11);e59-e65. doi: 10.1542 /pir.29-11-e59.

653

654

CHAPTER 24  Neonatal and Pediatric Pulmonary Disorders TTN delivered by cesarean section may develop pulmonary hypertension owing to retained lung fluid.143,144 A challenging clinical course, potentially requiring ECMO, may be required.

Congenital Diaphragmatic Hernia Congenital diaphragmatic hernia (CDH) is a complex

congenital disorder with high mortality. The incidence of CDH is roughly 1 in 2,500 births.145–147 CDH is a major medical concern and is not well known outside the realm of neonatology. A primary characterization of CDH is a hole in the diaphragm that allows abdominal organs to move into the chest, thus hindering lung development146,147 (Figure 24-24). As a result, CDH infants suffer a combination of various degrees of insufficient lung growth and pulmonary hypertension.146,147

Clinical Signs and Symptoms The first clinical manifestations of CDH are usually seen in prenatal ultrasonography findings. A CDH diagnosis can be made as early as 15 weeks’ gestation.148,149 An earlier gestational diagnosis oftentimes leads to potentially worse outcomes because this discovery indicates a more severe defect or pulmonary dysfunction.148,149 Prenatal US findings will usually show an improperly situated stomach as well as the intestines being located next to the heart.148,149 “Liver-up,” or the presence of the liver in the thorax, usually depicts a more severe form of CDH because it again indicates a larger defect or pulmonary dysfunction.148,149 At delivery, infants most generally exhibit respiratory distress (e.g., retractions and grunting) and cyanosis, although a delayed presentation is possible.148,149 During the neonatal assessment, CDH infants frequently present with a scaphoid abdomen (i.e., sucked inward) and barrel chest.148,149 Continuing with auscultation of the lungs, the clinician will hear poor air entry (i.e., diminished breath sounds)

Normal diaphragm development

FIGURE 24-24  Congenital diaphragmatic hernia. Printed with permission from Texas Children's Hospital.

on one side and bowel sounds on the affected side.148,149 A shift in cardiac sounds may also be heard because of the incorrect anatomic location of the heart.148,149 Furthermore, in patients with severe CDH, a pneumothorax may be found.148,149 Hypoxemia is a commonly seen clinical characteristic of CDH. Multiple factors, including pulmonary vascular abnormalities, the extent of lung hypoplasia, and the compression of lung units, contribute to worsening hypoxemia.148,149 Ongoing hypoxemia, along with right-to-left shunting, may cause tissue hypoxia and increases in metabolic acidosis.148,149 Pulmonary hypertension is another common clinical symptom in patients with CDH. Moreover, these anatomic irregularities and pulmonary hypertension can both contribute to further cardiac insufficiency.

Etiology During normal gestation, the diaphragm is fully formed by the 12th week. In CDH infants, a part of the diaphragm does not form correctly, resulting in a defect that causes the abdominal innards to enter the thoracic cavity.146 Classification of CDH is based upon the anatomic location of the defect. CDH can be classified as a posterolateral, anterior, or central defect.146 Posterolateral defects, also termed Bochdalek hernia, make up 90% of CDH cases, with the remaining 10% comprising anterolateral defects (Morgagni hernia) and relatively rare forms of total diaphragm absence.150 The majority of CDH cases occur on the left side with less frequent incidences on the right side or bilaterally.147,150

Epidemiology CDH occurs in 1 in every 2,000–3,000 newborns and accounts for 8% of all major congenital abnormalities.145 The risk of recurrence in future siblings is approximately 2%.145 Mortality and morbidity are traditionally difficult to calculate and sometimes underestimated

Congenital diaphragmatic hernia

Neonatal because of the “hidden mortality” in CDH. Hidden mortality refers to fetuses with hernias that die in utero or shortly after birth.151 Studies have found that hidden mortality significantly exists in this condition, with hidden CDH deaths at 45%.151 The presence of other abnormalities and associations (e.g., prematurity, low birth weight, and pneumothorax) has been correlated with poor outcome in these patients.

Pathology/Pathophysiology CDH has a very complex pathophysiology and remains weakly understood. Research experiments have demonstrated that incomplete growth of the lungs (pulmonary hypoplasia) occurs prior to diaphragm shortcomings.146 Using this evidence, researchers were able to show that lung growth is already affected prior to the development of the diaphragmatic hernia.152 This led to the “dual-hit hypothesis,” which postulates CDH as the result of developmental compromises. The first hit or compromise affects both lungs and occurs before diaphragm development as a result of genetic and environmental factors.152 The second hit affects only the ipsilateral lung and occurs after development of the defect, causing herniation of organs into the thorax.152 Retinoid (compounds chemically related to vitamin A) signaling disturbances may play a significant role in the pathophysiology of CDH.146 Additionally, studies have shown an increased risk for CDH associated with various maternal factors, including alcohol use, smoking, low intake of retinol, obesity, and antimicrobial drugs.146 Genetics is also being associated with congenital abnormalities in CDH. Genetic syndromes, chromosome abnormalities, and congenital anomalies have all been identified in CDH infants.146 Several cardiovascular malformations (CVMs) commonly coexist with CDH following the birth of these patients, including pulmonary hypoplasia, patent ductus arteriosus (i.e., an opening between two blood vessels leading from the heart), patent foramen ovale (i.e., a hole between the two atria in the heart), and intestinal malrotation.152

defects or hereditary abnormalities.153,154 In cases of isolated CDH (the only major health problem), pulmonary hypoplasia and PPHN are main causes of morbidity and mortality.153,154 Further studies are needed to determine a clear etiology and established risk factors of CDH, especially to help with prevention efforts.

Complications Neonatal research has documented that both pulmonary hyperplasia and

persistent pulmonary hypertension of the newborn (PPHN)

are chief complications following the repair of CDH.157 Histologic research has shown increased musculature in the pulmonary vasculature.152 Continued contraction of the vasculature can produce chronic constriction of the arterioles, resulting in pulmonary hypertension or PPHN.152 Good patient assessment and strict follow-up is necessary for patients who develop postoperative complications. CDH babies are at risk for long-term morbidities, including pulmonary diseases, GI disorders, growth failure, neurologic impairment, and chest wall deformities.146

Diagnostic Testing Prenatally, CDH is diagnosed by an US examination. Polyhydramnios is commonly present and is the main indicator in pregnancies complicated by CDH.155 The diagnosis of CDH is confirmed by radiographic imaging. The CXRs may indicate abdominal organs in the thorax as well as an abnormal cardiac axis or mediastinal shift in the opposite direction146,155 (Figure 24-25). Pulmonary hypoplasia can be measured by the severity

Risk Factors Risk factors contributing to the onset of CDH remain unclear. Studies have found CDH to be associated with several demographic risk factors, including male fetal gender, higher maternal age, Caucasian race, and maternal smoking.153,154 Additionally, maternal pre-gestational diabetes and alcohol use are related to the occurrence of CDH in infants.153,154 Several of these risk factors are modifiable and significant attention should be given to patient and family education. There are also several clinical characteristics related to poor outcomes that have been identified as risk factors in infants with CDH, such as low birth weight, size of the diaphragmatic defect, a low Apgar score, prematurity, air leaks, as well as the presence of other structural

FIGURE 24-25  Chest and abdominal radiograph showing a CDH. Reproduced with permission from James A. O'Neill Jr and The American Pediatric Surgical Association.

655

656

CHAPTER 24  Neonatal and Pediatric Pulmonary Disorders of fetal breathing movements.155 Postnatal clinical symptoms soon after birth also help in the diagnosis and management of CDH. The onset of symptoms may differ depending on the volume of innards in the thorax and the severity of pulmonary hypoplasia present.156 Undiagnosed patients may present with acute respiratory distress, a barrel-shaped chest, concave abdomen, the absence of breath sounds, shifted cardiac sounds, and bowel sounds in the chest.146 Some CDH infants remain asymptomatic and present later in life with CI symptoms or some other ailment.155 Prenatal diagnosis is advantageous as it can help in better management and intervention of the infant and mother, individualized patient education, and planned delivery in a skillful facility.146,155

Treatment and Management One essential management component of all CDH cases is parental counseling. Parents need to properly understand the severity of the disorder, disease process expectations, and potential outcomes. Furthermore, prenatal management of CDH consists of routine US surveillance for potential prenatal complications.146 Postnatal management has evolved to include lung-protective ventilation with possible permissive hypercapnia, infant stabilization prior to surgical repair, inhaled nitric oxide (iNO), HFV, or extracorporeal membrane oxygenation (ECMO) therapies.146 In the delivery room, the aim is to achieve adequate oxygenation and ventilation. Infants should receive a nasogastric (NG) tube to prevent further bowel enlargement.155 Severe CDH infants should be immediately intubated and placed on safe mechanical ventilation settings. Ventilatory strategies should consist of lung protection principles, maintaining an Spo2 of at least 85%, allowing for comfortable permissive hypercapnia, and stimulating spontaneous breathing.146 Bag-mask ventilation should be avoided as it can lead to bowel distension and further respiratory distress.146,155 ABG values should be used as ventilatory management determinants in infants with CDH.156 Once the cardiopulmonary functions are stabilized, usually in the first week of life, surgical repair can be accomplished. The operating approach consists of open or minimally invasive surgical techniques.146 The transabdominal approach is preferred and the standard technique for repair.157 If the abdominal cavity is inadequate, the transthoracic approach is used for good exposure to the defect.157 Generally, the closure method depends on the size and severity of the defect. Smaller defects are repaired with permanent sutures, whereas larger defects require a patch.146,155 In recent years, experimental surgical treatment approaches for CDH have been developed and used. Fetal tracheal occlusion therapy is an improved technique of fetal surgery.146,158 Outcomes have varied, with some studies reporting

reduced pulmonary hypoplasia while others failing to show improved survival.146,158 HFV and ECMO can be used as rescue therapies when conventional ventilation fails. Some studies have reported improved survival rates with both HFV and ECMO; however, discrepancies exist.146,155 Recent advancements in NICU protocols have significantly helped to reduce CDH mortality in hospital centers.152

Prognosis Despite the continuous improvement in knowledge and management of this disease, CDH still carries over a 50% mortality rate.155 Traditional therapies, including pulmonary vasodilators, pharmacologic paralysis, HFV, and ECMO, have all shown potential but made no noteworthy impact on the pulmonary hypertension issues facing these patients.155 Presently, iNO therapy, a potent pulmonary vasodilator, is the most common treatment for pulmonary hypertension in CDH infants.146 However, the benefits of blood pressure enhancement are debatable. The long-term outcomes and quality of life of CDH infants vary. Due to the high morbidity prevalence rates, the importance of close follow-up and long-term care among CDH survivors must be emphasized.

KNOWLEDGE CHECK QUESTIONS 1. True or False: Cyanotic heart defects are more dangerous than acyanotic heart defects. 2. True or False: IRDS is caused by weakness or underdevelopment of the chest muscles. 3. True or False: Positive pressure ventilation support in infants can lead to BPD.

Pediatrics The following sections will discuss the etiologic and pathophysiologic characteristics of several pediatric cardiopulmonary disorders of the respiratory system. These will include croup, epiglottitis, bronchiolitis, and foreign body obstruction (FBO).

Croup Croup, also known as acute laryngotracheitis or acute

laryngotracheobronchitis, is a common pediatric viral inflammatory condition.159,160 Croup generally affects the subglottic airway (i.e., larynx and trachea) but can extend as far as the bronchi.159,160 With this area being the narrowest part of the pediatric airway, significant airway obstruction is very common in these patients.

Pediatrics This respiratory tract disorder is characterized by a hoarse voice, cough, acute onset of stridor, and a varying degree of respiratory distress.159,160

by a Westley croup score of 6–11.163 A Westley croup score of greater than 11 signifies impending respiratory failure.163

Clinical Signs and Symptoms

Etiology

There tends to be a wide clinical spectrum of croup. Patients with croup initially present with nonspecific respiratory symptoms such as a sore throat, cough, and runny nose.161,162 Over the course of a few days, characteristic signs include low-grade fever, hoarseness, a seal-like barking cough, inspiratory stridor, and a variable degree of respiratory distress.161,162 Symptoms tend to worsen at night and usually resolve within 3–7 days but have been seen to last as long as 2 weeks.161,162 The clinical presentation of stridor has wide variation. Some children have stridor only during physical activity, while others have stridor accompanied by respiratory distress at rest.161,162 Substantial degrees of airway obstruction can even cause “quiet stridor” in certain patients.161,162 Milder cases may present with normal respiratory sounds, but more severe cases can have inspiratory and expiratory stridor, retractions, or even poor air entry.161,162 Fatigue and agitation occur and are due to respiratory distress, triggering hypoxemia and hypercarbia.161,162 Additional signs of respiratory distress include tachypnea, tachycardia, cyanosis, and poor muscle tone. Additionally, during severe coughing fits, respiratory arrest has been known to occur.161,162 Croup scoring systems have been created to assist clinicians in characterizing the severity of respiratory impairment in children with croup. The most widely used clinical score, demonstrated by its validity and reliability is the Westley croup score.163 The Westley croup score evaluates the severity of croup by considering 5 common symptoms: level of consciousness, stridor, cyanosis, air entry, and retractions163 (Table 24-3). The score for each of the symptoms is totaled. Children with a Westley croup score of 0–2 are considered to have mild croup.163 Those corresponding to a Westley croup score of 3–5 indicate moderate croup.163 Severe croup is denoted

Croup is caused by viruses spread through direct inhalation from a cough/sneeze or by contamination of hands with consequent touching of the face.164 Parainfluenza viruses (Types I, II, III) are the most common viral types causing croup outbreaks each year.164 They account for nearly 80% of all croup cases.164 Other etiologic agents include respiratory syncytial virus (RSV), adenovirus, and influenza viruses A and B.164 The chief entry points of the virus are the nose and nasopharynx.164 The infection spreads and eventually reaches the larynx and trachea. In some cases, the lower airways may also be affected and could necessitate additional evaluation to address concerns of secondary bacterial infections.164

Epidemiology Croup is the most common pediatric upper airway disorder, accounting for nearly 15% of the annual emergency department (ED) visits each year.165 It typically affects infants and toddlers between the ages of 6 months and 3 years, with a peak incidence in the second year of life.165 Croup occurs most often in early fall and winter but may present at any time.165 The male-to-female ratio is roughly 1.4:1 for croup.165 While infrequent, croup can also be a recurring disorder, with nearly 5% of patients experiencing more than 1 episode of croup.165

Pathology/Pathophysiology Recall that the narrowest portion of the pediatric airway is the subglottis, just below the vocal cords. This anatomic distinction predisposes children to airway obstruction and to infectious diseases, such as croup.166 Inflammation and edema of the subglottic airway are cause for concern. The infiltration of inflammatory cells

TABLE 24-3 Westley Croup Score165 Score Symptom

0

1

2

3

4

5

Stridor

None

With agitation

At rest w/stethoscope

At rest w/o stethoscope

N/A

N/A

Retractions

None

Mild

Moderate

Severe

N/A

N/A

Air Entry

Normal

Decreased

Markedly decreased

N/A

N/A

N/A

Cyanosis on Room Air

None

N/A

N/A

N/A

With agitation

At rest

Level of Consciousness

Normal

N/A

N/A

N/A

N/A

Disoriented

Modified from Li S. The Westley croup score. Acad Emerg Med. 2003;10(3):289. doi:10.1197/aemj.10.3.289.

657

658

CHAPTER 24  Neonatal and Pediatric Pulmonary Disorders can trigger swelling, which can significantly reduce airflow.166 Seal-like coughs, stridor, and chest wall retractions arise from the narrowing of the pediatric airway.161,166 Associated hoarseness is due to the reduced mobility of the vocal cords secondary to edema.161,166 In severe croup cases, hypoxemia may occur from the development of even greater airway obstruction, impaired alveolar ventilation, or V/Q mismatching.166

Risk Factors Individuals most at risk of getting croup are children between the ages of 6 months and 3 years.167 Preventing colds and the flu, frequent hand washing, and up-to-date vaccinations can help to stop the incidence of croup.167 Other risk factors for developing croup include seasonal variation, prematurity, and other cases of viral infections.167

Complications Complications due to croup are sporadic. In most cases, less than 5% of patients diagnosed with croup need in-patient hospitalization and less than 2% of those require intubation tactics.159 Mortality from croup has occurred in as little as 0.5% of intubated patients, provided good airway management is carried out.159 A secondary bacterial infection, such as pneumonia or tracheitis, may result from croup. Additionally, conditions including pulmonary edema, pneumothorax, pneumomediastinum, ear infections, and lymphadenitis (i.e., lymph node inflammation) have been reported.159 Poor nutritional status and increased fluid loss can lead to patients requiring intravenous fluid hydration.159

Diagnostic Testing Croup is a clinical diagnosis, with the past medical history and physical assessment findings presenting as clues. Laboratory tests rarely confirm the diagnosis; however, white blood cell (WBC) count and differential can help to identify the specific etiologic agent type.164,168 Nasal washing can help to determine isolation precautions in the hospital setting and to decide whether antiviral therapies should be initiated.164,168 Pulse oximetry is useful to assess decompensating respiratory status and the demand for supplemental oxygen therapy. ABGs are necessary only if respiratory failure arises. Fluid support may be required to maintain the needed fluid volume. Laryngoscopy is indicated only in unusual cases.164,168 CXRs can help confirm a presumptive diagnosis or exclude other disorders. Lateral neck films detect haziness in the subglottic airway or a distended hypopharynx, which contrast epiglottitis findings.169,170 The AP radiograph of the neck classically shows subglottic narrowing or the steeple sign169,170 (Figure 24-26). While helpful, these radiographic findings are seen only in roughly 50% of clinical croup cases.169,170

FIGURE 24-26  Neck radiograph of croup showing steeple sign. Reproduced with permission from American Academy of Family Physicians.

Treatment and Management Treatment and management recommendations for croup are based on the severity of symptoms and any corresponding assessments. Most mild croup cases can be successfully treated at home using humidified mist, anti-fever medications, head elevation, and continued parental monitoring.171–173 In the cases of severe respiratory distress, a thorough evaluation should be performed to determine airway patency and maintenance of oxygenation and ventilation.171–173 Keeping children as comfortable as possible and avoiding painful interventions can prevent agitation, reduce respiratory distress, and decrease oxygen therapy requirements. Careful monitoring of vital signs and nutritional/ hydration status is important. Due to their antiinflammatory capabilities, corticosteroids are beneficial in the treatment of croup. Corticosteroids are known to decrease laryngeal edema and reduce the inflammatory reaction.174 Dexamethasone is the most common corticosteroid used for the treatment of croup. Studies have shown that if administered within the first 24 hours, a single dose of dexamethasone has been effective in reducing overall croup severity.174 The route of administration (i.e., intravenously, intramuscularly, or orally) is patient dependent and has shown to have the same efficacy toward the presenting illness.174 Nebulized racemic epinephrine is typically reserved for croup patients with moderate-to-severe respiratory distress. Epinephrine works by adrenergic stimulation, leading to improvements in laryngeal edema.175 It takes effect immediately and has shown to have effective therapeutic benefits within the first 30 minutes, lasting up to 2 hours.175 Due to the short half-life of epinephrine,

Pediatrics a single dose may relieve symptoms, but a repeat dose could be required. Clinicians should continue to monitor these patients for the possible return of symptoms, which include recurring bronchospasm, worsening respiratory distress, and tachycardia.175 A system-wide study showed that patients who received corticosteroids and single-dose racemic epinephrine were managed differently than those who received multidose racemic epinephrine and corticosteroids.174,175 Higher rates of hospital admission were seen in patients who received only single-dose racemic epinephrine treatments in the ED.174,175 The administration of heliox can be a beneficial treatment option for select patients with croup. Heliox can be dispensed as 80:20, 70:30, or 60:40 mixtures; however, patients requiring less than 40% oxygen will not see the benefits of heliox therapy. By using heliox, turbulent airflow is transformed into a more laminar flow, thus bypassing obstructions and lessening airway resistance.176 This lower density gas carries oxygen and medications through the narrowed airways, thereby decreasing the work of breathing and improving gas exchange.176 High costs and delivery setup complexity are some limiting factors to heliox therapy. Some recent trials have demonstrated no advantageous benefits of heliox therapy over traditional modalities, while other studies have shown it to be equally effective to racemic epinephrine in the treatment of moderate-to-severe croup.176 Heliox has also shown to improve symptoms in patients failing to improve with racemic epinephrine treatments.176 Heliox serves as a therapeutic bridge until the underlying condition can be treated. Infants experiencing severe respiratory distress may require ventilatory support due to increasing respiratory fatigue and worsening hypercarbia.176 Discharge can occur only if the patient demonstrates clinical stability.

Prognosis The prognosis of croup is excellent. Advancements in treatment and management have altered this disorder from a once fatal upper airway disease to a somewhat self-limiting disorder. The majority of croup cases can be treated as outpatients. Patients younger than 6 months, an unusually long duration of symptoms, and those with recurring croup should be evaluated for congenital anomalies.160

Epiglottitis Epiglottitis, also termed supraglottitis, is a bacterial

inflammation of the structures above the insertion of the glottis (i.e., epiglottis, surrounding tissues, and the supraglottic larynx).177,178 The epiglottis is the most common spot of swelling. As the edema increases, the epiglottis is repositioned posteriorly, causing gradual airway obstruction.177,178 The anatomic features of the epiglottis are significantly different between children

and adults. The epiglottis is located more anteriorly and superiorly, and it is at a greater angle to the trachea in children.177,178 Acute epiglottitis and associated life-threatening airway obstruction have substantial morbidity and mortality consequences.177,178

Clinical Signs and Symptoms An abrupt onset of severe respiratory symptoms characterizes epiglottitis. If not quickly recognized, symptoms can quickly progress to severe airway obstruction or respiratory arrest. Symptoms typically begin with fever, followed by stridor, labored breathing, dysphagia, hoarseness, refusal to eat, sore throat, and anxiety.161 The onset of classic epiglottitis is easily identified using the clinical triad: drooling, dysphagia, and distress.161 Upon physical examination, children appear restless, irritable, and extremely anxious.161 Children may sit in the tripod position (i.e., chin hyperextended and body leaning forward), which maximizes airflow entry and improves diaphragmatic excursion.161 During an examination of the oropharynx, a swollen, red epiglottis can be seen. Patients may present with stridor, but as the epiglottitis progresses, breath sounds may become diminished as a result of severe airway obstruction.161 A clinician capable of obtaining an airway should attend to this patient at all times.

Etiology Formerly, Haemophilus influenza type b (Hib) was the most common cause (>90%) of pediatric epiglottitis cases.178 However, since the introduction of the Hib vaccine, the main contributing agent of epiglottitis has changed. Bacterial causes of epiglottitis include Streptococcus pneumoniae, Staphylococcus aureus, Klebsiella pneumoniae, and Haemophilus parainfluenzae.178 While viruses do not routinely cause epiglottitis, a previous viral infection can increase the chances of a bacterial infection occurring. Viral agents, including herpes simplex virus, parainfluenzae virus, human immunodeficiency virus, and varicella (i.e., chickenpox), can cause primary or secondary infections to occur.178 Noninfectious etiologies such as trauma or thermal injury may also cause epiglottic inflammation.178

Epidemiology Epiglottitis is a rare condition most commonly seen in children between 2 and 5 years old.179 Studies have shown a seasonal variation in pediatric epiglottitis incidence.179 A comparative study found a 10-fold decline in acute epiglottitis admissions in large U.S. children’s hospitals.179 Generally, studies have shown no racial predominance for epiglottitis; however, a recent report revealed higher incidence in black and Hispanic patients.179 Epiglottitis is also a male-dominant disorder, which remains true even with changing epidemiology.179

659

660

CHAPTER 24  Neonatal and Pediatric Pulmonary Disorders

Pathology/Pathophysiology The pathophysiology of epiglottitis involves the respiratory transmission of bacteria through close contact. Infectious pathogens penetrate the mucosa and invade the bloodstream, leading to infections of the epiglottis and surrounding tissues.180,181 Infection of the epiglottis results in acute swelling of the airways. Respiratory distress or ultimately arrest can occur due to severe airway obstruction, aspiration of secretions, or mucus plugging.180,181

Risk Factors Several factors increase the risk of a child developing epiglottitis. Children younger than 1 year of age who have not completed the Hib vaccine series are at a higher risk for emerging epiglottitis.178 While unclear, the male gender is more likely to develop epiglottitis than females.178 Increased exposure to respiratory infections (e.g., schools or day care centers) heightens the risk of getting epiglottitis.178 Furthermore, a weakened immune system can make it more challenging to combat infections, making it easier for epiglottitis to develop.178

Complications During the progression of epiglottitis, other infections are possible. The most commonly associated infection is pneumonia.182 The two most common complications are accidental extubation and respiratory arrest.182 Additionally, complications related to an inflamed epiglottis include airway obstruction as well as aspiration, tracheal stenosis, pneumothorax, and epiglottic abscess.182

Diagnostic Testing The diagnosis of epiglottitis requires a superior clinical inkling and careful recognition of the clues provided in the patient’s presentation. Securing and maintaining the airway is of utmost importance. In patients with mild cases, visualization of the epiglottis may be performed via gentle compression of the tongue with a tongue depressor.183,184 While laryngoscopy is the best way to confirm diagnosis via direct visualization of the epiglottis, it is not advised without first securing the airway.183,184 Refrain from progressing with diagnostic testing until airway maintenance is performed. Laboratory test results show an elevated WBC count and positive blood cultures for the bacterial etiologic agent.183,184 In highly suspected epiglottitis cases, radiography is not indicated. In less clear cases, radiologic images can establish the diagnosis and rule out other conditions (i.e., croup or FBO).185 A lateral neck radiograph may demonstrate the thumb sign, indicating a swollen epiglottis protruding from the hypopharynx185 (Figure 24-27).

FIGURE 24-27  Neck radiograph of the epiglottitis showing

thumb sign.

Case courtesy of Dr Andrew Ho, Radiopaedia.org, rID: 22906.

Treatment and Management The typical treatment and management of epiglottitis include treating potential hypoxemia, maintaining the airway, relieving the airway obstruction, and eradicating the infectious agent.186,187 Oxygen therapy is used to treat hypoxemia in distressed patients while stabilizing the airway.186,187 Clinicians should always be prepared to evaluate the ABCs (i.e., airway, breathing, and circulation). If epiglottitis is suspected, emergency airway management should be performed. Mortality rates for children who require, but do not receive, endotracheal intubation is as high as 10%.186,187 Because there is no underlying lung disease, clinicians should place the patient on normal rest ventilator settings. Appropriate antibiotic therapy should be tailored to the cause of the bacterial infection. Patients recovering from epiglottitis may be extubated when an air leak around the endotracheal tube occurs at 24–48 hours.186,187 Children should be placed on supplemental oxygen therapy and closely monitored. Clinicians must be prepared for emergent reintubation situations, as patients with epiglottitis have a substantial risk of decompensating following extubation.186,187

Prognosis Patients with epiglottis, and whose airways have been properly secured, have a good prognosis. There is a less than 1% mortality rate in these patients.186 There are no long-term complications associated with epiglottitis and discharge usually occurs within a week.186

Pediatrics

Bronchiolitis Bronchiolitis is an acute, viral inflammation of the

bronchioles. It is typically a self-limiting disorder with a wide spectrum of clinical symptoms. Bronchiolitis is characterized by acute swelling, increased mucus production, and bronchoconstriction.188,189 It is the most common cause of lower respiratory tract infection in infants younger than 1 year of age.188,189 Although it occurs in children of all ages, severe bronchiolitis has a peak incidence in infants between 3 and 6 months of age.188,189 Despite the published clinical practice guidelines, there are still inconsistencies in the management and treatment of patients with bronchiolitis. More standardized bronchiolitis care can lead to fewer patient hospitalizations and shorter length of stays.

Clinical Signs and Symptoms The past medical history and clinical assessment form the finding of bronchiolitis. Initial clinical manifestations are subtle, including difficult feedings, tachypnea, expiratory wheezing, low-grade fever, and nasal congestion.190,191 Feeding intolerance can lead to dehydration and trigger thickened secretions. Progression of bronchiolitis leads to the development of a cough, dyspnea, and profound inspiratory and expiratory wheezing.190,191 Severe cases result in impending respiratory failure secondary to lower respiratory tract obstruction and inflammation.190,191 Hypoxia is the best predictor to determine the severity of the disease. This V/Q mismatch occurs because of the collapse of the bronchioles and atelectasis. Typically, severity worsens over the first 72 hours, then plateaus, and rectifies over several weeks. Though several severity-scoring systems exist, none are widely used and few prove predictive validity. While rarely lasting longer than a few days, careful monitoring is required to detect apneic episodes in these patients. Additional clinical signs include retractions, nasal flaring, and cyanosis.190,191

Etiology Most cases of bronchiolitis are caused by a variety of viral pathogens, but RSV is the most common.191,192 RSV accounts for nearly 80% of all bronchiolitis cases in children younger than 2 years.191,192 Other etiologic agents include rhinovirus, parainfluenza virus, adenovirus, and coronavirus.191,192 Bronchiolitis is highly contagious and is spread via direct contact with nasal secretions or respiratory droplets.191,192 Once contaminated, RSV can survive on the hands for a considerable amount of time, making good hand-washing technique and infection prevention imperative.

Epidemiology In the United States, nearly 125,000 hospitalizations and 250 infant deaths due to bronchiolitis occur each

year.193 Of those patients hospitalized, roughly 2–5% require mechanical ventilation support.193 Recall that RSV is the most common viral cause of bronchiolitis. Nearly all children are infected with RSV at least once by the age of 2, but peak numbers occur between 2 and 3 months following birth.193 The highest RSV infections occur in winter months, with peak season happening from October to February.193

Pathology/Pathophysiology Once viruses penetrate the bronchioles (i.e., small airways) and cause infection, bronchiolar injury and subsequent inflammation occur.194,195 A complex inflammatory response develops in the epithelium, resulting in necrosis.194,195 The release of cytokines amplifies the inflammatory response into the airways. Bronchiolar injury is caused by inflammation, edema, and debris in the respiratory tract.194,195 Adverse effects of bronchiolar injury, including increased mucus production, airway obstruction, air trapping, and atelectasis, typically begin to appear about 24 hours following infection.194,195 The extent of mucus plugging prompts various degrees of airway obstruction, the principal contributing factor to V/Q mismatching, hypoxemia, and, ultimately, respiratory failure.194,195

Risk Factors Risk factors described with bronchiolitis include younger gestational age (i.e.,