ABC of Prehospital Emergency Medicine [2 ed.] 1119698324, 9781119698326

Table of contents :
ABC of Prehospital Emergency Medicine
Contents
Contributor list
Foreword
Preface
1 Prehospital Emergency Medicine
Part 1 Operational Practice
2 Activation and Deployment
3 Responder Safety
4 Extrication
5 The First Five Minutes and the Primary Survey
6 Airway Assessment and Management
7 Breathing Assessment and Management
8 Circulation Assessment and Management
9 Prehospital Monitoring
10 Prehospital Ultrasound
11 Analgesia and Sedation
12 Transfer and Retrieval
Part 2 Providing Prehospital Trauma Care
13 Abdominal Injury
14 Pelvic Injury
15 Head Injury
16 Spinal Injuries
17 Extremity Injury
18 Burns
19 Suspension and Crush Injury
20 Ballistic and Blast Injury
21 Cardiac Arrest
Part 3 Providing Prehospital Medical Care
22 Acute Medical Emergencies
23 Overdose and Poisoning
Part 4 Special Groups
24 The Paediatric Patient
25 The Obstetric Patient
26 The Bariatric Patient
27 The Older Patient
28 Mental Health Crisis
29 Capacity
Part 5 Environmental
30 Environmental Injuries
31 Drowning
32 Diving Emergencies
33 Altitude Illness
Part 6 Emergency Preparedness
34 Mass Casualty Incident Management
35 Chemical, Biological, Radiation, and Nuclear Incidents
36 Mass Gatherings
Part 7 Clinical Governance and Professional Skills
37 Clinical Governance
38 Medicolegal and Ethical Aspects
39 Human Factors, Ergonomics, Safety, and Culture
40 Human Performance
41 Research and Development
Index
EULA

Citation preview

Prehospital Emergency Medicine

Prehospital Emergency Medicine SECOND EDITION EDITED BY

Tim Nutbeam

Lead Doctor for the Devon Air Ambulance Honorary Professor of Prehospital Emergency Medicine (PHEM), University of Plymouth Consultant in Emergency Medicine at University Hospitals Plymouth NHS Trust Plymouth, UK

Matt Boylan

Consultant in Military Emergency Medicine and PHEM University Hospitals Birmingham NHS Foundation Trust Birmingham, UK

Caroline Leech

Deputy Clinical Lead for The Air Ambulance Service, Rugby, UK Consultant in Emergency Medicine University Hospitals Coventry & Warwickshire NHS Trust Coventry, UK

Clare Bosanko

Critical Care Doctor for the Devon Air Ambulance Consultant in Emergency Medicine, University Hospitals Plymouth NHS Trust Plymouth, UK

This edition first published 2023 © 2023 John Wiley & Sons Ltd Edition History 1e © 2013 John Wiley & Sons Ltd All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by law. Advice on how to obtain permission to reuse material from this title is available at http://www.wiley.com/go/permissions. The right of Tim Nutbeam, Matt Boylan, Caroline Leech and Clare Bosanko to be identified as the authors of the editorial material in this work has been asserted in accordance with law. Registered Office(s) John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, USA John Wiley & Sons Ltd, 9600 Garsington Road, Oxford, OX4 2DQ, UK For details of our global editorial offices, customer services, and more information about Wiley products visit us at www.wiley.com. Wiley also publishes its books in a variety of electronic formats and by print-on-demand. Some content that appears in standard print versions of this book may not be available in other formats. Trademarks: Wiley and the Wiley logo are trademarks or registered trademarks of John Wiley & Sons, Inc. and/or its affiliates in the United States and other countries and may not be used without written permission. All other trademarks are the property of their respective owners. John Wiley & Sons, Inc. is not associated with any product or vendor mentioned in this book. Limit of Liability/Disclaimer of Warranty The contents of this work are intended to further general scientific research, understanding, and discussion only and are not intended and should not be relied upon as recommending or promoting scientific method, diagnosis, or treatment by physicians for any particular patient. In view of ongoing research, equipment modifications, changes in governmental regulations, and the constant flow of information relating to the use of medicines, equipment, and devices, the reader is urged to review and evaluate the information provided in the package insert or instructions for each medicine, equipment, or device for, among other things, any changes in the instructions or indication of usage and for added warnings and precautions. While the publisher and authors have used their best efforts in preparing this work, they make no representations or warranties with respect to the accuracy or completeness of the contents of this work and specifically disclaim all warranties, including without limitation any implied warranties of merchantability or fitness for a particular purpose. No warranty may be created or extended by sales representatives, written sales materials or promotional statements for this work. The fact that an organization, website, or product is referred to in this work as a citation and/or potential source of further information does not mean that the publisher and authors endorse the information or services the organization, website, or product may provide or recommendations it may make. This work is sold with the understanding that the publisher is not engaged in rendering professional services. The advice and strategies contained herein may not be suitable for your situation. You should consult with a specialist where appropriate. Further, readers should be aware that websites listed in this work may have changed or disappeared between when this work was written and when it is read. Neither the publisher nor authors shall be liable for any loss of profit or any other commercial damages, including but not limited to special, incidental, consequential, or other damages. Library of Congress Cataloging-in-Publication Data Names: Nutbeam, Tim, editor. | Boylan, Matthew, editor. | Leech, Caroline (Consultant in emergency medicine), editor. | Bosanko, Clare, editor. Title: ABC of prehospital emergency medicine / edited by Tim Nutbeam, Matt Boylan, Caroline Leech, Clare Bosanko. Description: 2nd edition. | Hoboken, NJ : John Wiley & Sons, 2023. | Includes bibliographical references and index. Identifiers: LCCN 2022057616 (print) | LCCN 2022057617 (ebook) | ISBN 9781119698326 (paperback) | ISBN 9781119698340 (pdf) | ISBN 9781119698333 (epub) Subjects: MESH: Emergency Medicine--methods | Emergency Medical Services--methods Classification: LCC RC86.8 (print) | LCC RC86.8 (ebook) | NLM WB 105 | DDC 616.02/5--dc23/eng/20230221 LC record available at https://lccn.loc.gov/2022057616 LC ebook record available at https://lccn.loc.gov/2022057617 Cover Image: © Gorodenkoff/Adobe Stock Photos Cover Design: Wiley Set in 9/12pt MinionPro by Integra Software Services Pvt. Ltd, Pondicherry, India

Contents

Contributor list, viii Foreword, xi Preface, xii 1 Prehospital Emergency Medicine, 1

Part 1 Operational Practice, 3 2 Activation and Deployment, 5

Stephanie Cowan, Iwan Davies, and Matthew Boylan

3 Responder Safety, 10

Clare Bosanko and Dave Dungay

4 Extrication, 15

Malcolm Russell and Rob Fenwick

5 The First Five Minutes and the Primary Survey, 23

Tim Nutbeam and Matthew Boylan

6 Airway Assessment and Management, 26

Tom Renninson, Mårten Sandberg, Tim Hooper, Marius Rehn, Per Kristian Hyldmo, and David Lockey

7 Breathing Assessment and Management, 38

Per Kristian Hyldmo, Marius Rehn, and Mårten Sandberg

8 Circulation Assessment and Management, 46

Jake Turner and Matthew Boylan

9 Prehospital Monitoring, 57

Tim Harris and Peter Shirley

10 Prehospital Ultrasound, 63

Tim Harris, Adam Bystrzycki, and Stefan Mazur

11 Analgesia and Sedation, 72

Jonathan Hulme, Philip Keane, and Tony Sim

12 Transfer and Retrieval, 80

Richard Browne and Scott Grier

Part 2 Providing Prehospital Trauma Care, 89 13 Abdominal Injury, 91

Ed Barnard and Keith Roberts

14 Pelvic Injury, 94

Keith Porter, Caroline Leech, and Matt O’Meara

15 Head Injury, 97

Jeremy Henning, Clare Hammell, and Matthew Boylan v

vi

Contents

16 Spinal Injuries, 102

Mark Wilson and Tim Nutbeam

17 Extremity Injury, 107

Matt O’Meara, Caroline Leech, and Keith Porter

18 Burns, 110

Christopher J. Lewis and Keith P. Allison

19 Suspension and Crush Injury, 119

Jason van der Velde and Caroline Leech

20 Ballistic and Blast Injury, 123

Matthew Boylan and William Charlton

21 Cardiac Arrest, 130

Walter Kloeck, Martin Botha, David Kloeck, and Clare Bosanko

Part 3 Providing Prehospital Medical Care, 139 22 Acute Medical Emergencies, 141

Ewan Barron and Adam Low

23 Overdose and Poisoning, 151

Peter Welby-Everard and Ian Gurney

Part 4 Special Groups, 157 24 The Paediatric Patient, 159

Ben Lawton and John Glasheen

25 The Obstetric Patient, 166

Tracy-Louise Appleyard and Caroline Leech

26 The Bariatric Patient, 176

Hannah Bawdon and Surpreet Grewal

27 The Older Patient, 181

Fionna Lowe and Keniesha Miller

28 Mental Health Crisis, 184

Rob Cole, Richard Corrall, and Carly Lynch

29 Capacity, 189

Rob Cole, Richard Corrall, and Carly Lynch

Part 5 Environmental, 193 30 Environmental Injuries, 195

William Charlton and Omar Tayari

31 Drowning, 203

Mike Tipton and Paddy Morgan

32 Diving Emergencies, 207

Tudor A. Codreanu

33 Altitude Illness, 212

Harvey Pynn and Lucy Obolensky

Part 6 Emergency Preparedness, 219 34 Mass Casualty Incident Management, 221

Jamie Vassallo and Damian Keene

35 Chemical, Biological, Radiation, and Nuclear Incidents, 228

Niall Aye Maung and William Charlton

36 Mass Gatherings, 234

Lee Wallis and Wayne Smith

Contents

Part 7 Clinical Governance and Professional Skills, 237 37 Clinical Governance, 239

Clare Bosanko

38 Medicolegal and Ethical Aspects, 243

Craig M. Klugman and Jennifer Bard

39 Human Factors, Ergonomics, Safety, and Culture, 249

Chris Frerk, Tom Hurst, and Neil Jeffers

40 Human Performance, 253

Tom Evens, Alison Sanders, and Chris Shambrook

41 Research and Development, 259

Jamie Miles, Willem Stassen, Niroshan Siriwardena, and Suzanne Mason

Index, 262

vii

Contributor list

Peter Aitken

James Cook University, Townsville, QLD, Australia

Keith P. Allison

Consultant Plastic Surgeon, James Cook University Hospital, Middlesbrough, UK

William Charlton

Academic Department of Military General Practice, UK Kent Surrey Sussex Air Ambulance

Tudor A. Codreanu

Southmead Hospital, Bristol, UK

State Health Incident Coordination Centre, Western Australian Department of Health Emergency Department, Critical Care Directorate, Busselton Health Campus, Busselton, West Australia

Jennifer Bard J.D.

Rob Cole

Tracy-Louise Appleyard

University of Florida Levin College of Law, Gainesville, FL USA

Ed Barnard

Military Consultant in Emergency Medicine (Prehospital Emergency Medicine) Cambridge University Hospitals NHS Foundation Trust, UK East Anglian Air Ambulance, UK

Ewan Barron

West Midlands Deanery, Birmingham, UK

Hannah Bawdon

West Midlands Ambulance Service, UK

Richard Corrall

West Midlands Ambulance Service, UK

Stephanie Cowan

West Midlands CARE Team The Air Ambulance Service, UK

Iwan Davies

Sandwell and West Birmingham Hospital, Birmingham, UK

West Midlands CARE Team The Air Ambulance Service, UK

Clare Bosanko

Tim Draycott

Devon Air Ambulance, UK University Hospitals Plymouth NHS Trust

Southmead Hospital, Bristol, UK

Martin Botha

Dave Dungay

University of the Witwatersrand, Johannesburg, South Africa

Devon Air Ambulance, UK

Matthew Boylan

Tom Evens

West Midlands Ambulance Service MERIT, Birmingham, UK Royal Defence for Defence Medicine, University Hospitals Birmingham, Birmingham, UK

Richard Browne

Queen Elizabeth Hospital, Birmingham, United Kingdom ACCOTS Adult Critical Care Transfer Service, Birmingham, UK

Adam Bystrzycki

Alfred Hospital, Melbourne, VIC, Australia

viii

Ambulance Service of New South Wales, Australia

Rob Fenwick

Consultant Nurse, Emergency Department, Wrexham Maelor Hospital, UK

Chris Frerk

Consultant Anaesthetist at Northampton General Hospital, Trustee Clinical Human Factor Group, UK

Contributor list

John Glasheen

High Acuity Response Unit, Queensland Ambulance Service, Queensland, Australia Lifeflight Retrieval Medicine, Queensland, Australia

Surpreet Grewal

Birmingham School of Anaesthesia, Birmingham, UK

Scott Grier

Southmead Hospital, Bristol, United Kingdom Retrieve Adult Critical Care Transfer Service, UK

Ian Gurney

Defence Consultant Advisor in Emergency Medicine, Academic Dept of Military Emergency Medicine, UK

Clare Hammell

Ben Lawton

Emergency Department, Logan Hospital, Queensland, Australia Queensland Children’s Hospital, Queensland, Australia Don’t Forget The Bubbles School of Medicine, University of Queensland, Queensland, Australia

Caroline Leech

Deputy Clinical Lead for The Air Ambulance Service, Rugby, UK Consultant in Emergency Medicine, University Hospitals Coventry & Warwickshire NHS Trust, Coventry, UK

Christopher J. Lewis

Consultant Burn Surgeon, Royal Victoria Infirmary, Newcastle upon Tyne, UK

Mark Little

James Cook University, Townsville, QLD, Australia

David Lockey

Leighton Hospital, Crewe, UK

North Bristol NHS Trust, Bristol, UK London’s Air Ambulance. Barts Health NHS Trust

Tim Harris

Adam Low

Royal London Hospital, London, UK

Jeremy Henning

The James Cook University Hospital, Middlesbrough, UK

Tim Hooper

Raigmore Hospital, NHS Highland, Inverness, Scotland

Jonathan Hulme

Sandwell and West Birmingham NHS Trust, City Hospital, Birmingham, UK West Midlands Ambulance Service (WMAS) University NHS Foundation Trust, West Midlands, UK Midlands Air Ambulance Charity, West Midlands, UK

Tom Hurst

London’s Air Ambulance, Bart’s Health, UK

Per Kristian Hyldmo

University Hospitals Birmingham NHS Foundation Trust & Midland Air Ambulance Charity, UK

Fionna Lowe

Derriford Hospital, Plymouth Hospitals NHS Trust, Plymouth, UK

Carly Lynch

London Ambulance Service, UK

Rod Mackenzie

Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK

Assiah Mahmood

Magpas Helimedix, St. Ives, UK

Kristyn Manley

Southmead Hospital, Bristol, UK

Sorlandet Hospital, Kristiansand, Norway Faculty of Health Sciences, University of Stavanger, Stavanger, Norway

Suzanne Mason

Neil Jeffers

Niall Aye Maung

Philip Keane

Stefan Mazur

London’s Air Ambulance, UK

Wye Valley Hospitals NHS Trust, Hereford County Hospital, Hereford, UK

Damian Keene

University of Sheffield, UK

Academic Department of Military General Practice, UK

MedSTAR, South Australian Emergency Medical Retrieval Service, SA, Australia

Department of Military Anaesthesia and critical care, Birmingham, UK University Hospitals Birmingham, Birmingham, UK

Jamie Miles

Walter Kloeck

Keniesha Miller

David Kloeck

Paddy Morgan

University of the Witwatersrand, Johannesburg, South Africa

University of the Witwatersrand, Johannesburg, South Africa

Craig M. Klugman

DePaul University, Chicago, IL USA

ix

University of Sheffield, UK

Derriford Hospital, Plymouth Hospitals NHS Trust, Plymouth, UK

Extreme Environments Laboratory, School of Sport, Health & Exercise Science, University of Portsmouth, Portsmouth, UK Emergency Medical Retrieval and Transfer Service (EMRTS) Cymru, Cymru North Bristol NHS Trust, Bristol, UK

x

Contributor list

Lucas A. Myers

Alison Sanders

Ian Norton

Chris Shambrook

Tim Nutbeam

Peter Shirley

Matt O’Meara

Tony Sim

Lucy Obolensky

Niroshan Siriwardena

Mayo Clinic Medical Transport, Mayo Clinic, Rochester, MN, USA

Royal Darwin Hospital, Darwin, NT, Australia

Derriford Hospital, Plymouth Hospitals NHS Trust, Plymouth, UK

University Hospitals of North Midlands, UK

GP, Programme Lead Global and Remote Healthcare Masters University of Plymouth, UK

Andrew Pearce

Royal Adelaide Hospital, Adelaide, SA, Australia

Keith Porter

University Hospital Birmingham, UK

Harvey Pynn

Consultant in Emergency Medicine and Critical Care doctor, Bristol, UK

Marius Rehn

Faculty of Health Sciences, University of Stavanger, Stavanger, Norway Division of Prehospital Services, Air Ambulance Department, Oslo University Hospital, Oslo, Norway Norwegian Air Ambulance Foundation, Oslo, Norway

Tom Renninson

North Bristol NHS Trust, Bristol, UK Emergency Medical Retrieval and Transfer Services, Wales, UK

Keith Roberts

University Hospitals Birmingham, UK

Malcolm Russell

Emeritus Medical Director, Air Ambulance Kent, Surrey & Sussex Clinical Governance Lead, Midlands Air Ambulance Charity, Medical Director UKFire & Rescue Services International Search and Rescue (UK ISAR) Team, Mercia Accident Rescue Service – responding BASICS doctor

Christopher S. Russi

Mayo Clinic Medical Transport, Mayo Clinic, Rochester, MN, USA

Mårten Sandberg

Division of Prehospital Services, Air Ambulance Department, Oslo University Hospital, Oslo, Norway

Barts Health NHS Trust, Imperial College Healthcare NHS Trust, UK

PlanetK Performance Systems, UK

Royal London Hospital, London, UK

Wye Valley Hospitals NHS Trust, Hereford County Hospital, Hereford, UK

University of Lincoln, UK

Wayne Smith

University of Cape Town, South Africa

Willem Stassen

University of Cape Town, South Africa

Omar Tayari

Institute of Naval Medicine, Gosport, UK

Mike Tipton

Extreme Environments Laboratory, School of Sport, Health & Exercise Science, University of Portsmouth, Portsmouth, UK

Jake Turner

Nottingham University Hospitals NHS Trust, Nottingham, UK The Air Ambulance Service, Rugby, UK West Midlands Ambulance Service MERIT, Birmingham, UK

Jamie Vassallo

Academic Department of Military Emergency Medicine, Royal Centre for Defence Medicine, Birmingham, UK

Jason van der Velde

Cork University Hospital, Cork, Ireland

Lee Wallis

University of Cape Town, South Africa

Peter Welby-Everard

Specialty Trainee, Emergency Medicine, Defence Medical Services

Foreword

Dominique Jean Larrey, a French surgeon and military doctor practicing in the late 1700s, is often cited as the father of modern-day Prehospital Emergency Medicine (PHEM). His vision and commitment to provide care at the point of wounding, triage his patients on the basis of clinical need and transport them to battlefield hospitals in his flying ambulances was the blueprint of present-day PHEM practice. In the face of adversity, he provided contemporary medicine where patients needed it most, and at the same time created innovative practices such as triage. Such achievements remain inspirational today. The ‘roots’ of PHEM by this measure are admittedly short, especially when compared to those of hallowed medical establishments that can trace their practices and buildings back nearly 1000 years. With this comes a need for PHEM to make up for lost ground. It is therefore with huge pride for our sub-speciality I see the efforts of the contributors in this second edition of the ABC of Prehospital Emergency Medicine making such significant strides in bringing together our modern-day understanding of the diseases we treat and defining modern PHEM practice. The content of the first edition has been re-structured with the addition of new chapters such as Human Performance and Human

Factors. In keeping with Larrey’s desire to innovate, our modern-day understanding of bleeding mimics are described, as well as, impact brain apnoea, and the interventions of REBOA (Resuscitative Endovascular Balloon Occlusion of the Aorta) and e-CPR (Extracorporeal Membrane Oxygenation Cardiopulmonary Resuscitation). Our understanding of our patient’s pathologies and physiology is forever evolving: as are the complexities of interventions we can deliver. The second edition of the ABC of Prehospital Emergency Medicine reflects this evolution and will give any practitioner of PHEM a modern bedrock of understanding that will undoubtedly help the patients they tend. I would recommend it to all. Dr Gareth Davies Consultant in Emergency Medicine & Prehospital Care, Barts Health Trust Emeritus Medical Director London’s Air Ambulance Consultant in Emergency Medicine & Prehospital Care Nobles’ Hospital, Isle of Man Chief Medical Officer Isle of Man TT

xi

Preface

The first edition of this book was conceived 15 years ago in recognition of the paucity of resources available for practitioners in the growing field of Prehospital Emergency Medicine. Then the project had two clear aims: ●

●

To present accessible, cutting edge, expert opinion on core PHEM topics To provide the reader with the practical knowledge and resources to put this knowledge into clinical practice

Published in 2013, the first edition brought together an international field of experienced prehospital practitioners to share their knowledge and expertise in the accessible ABC format. Since then Prehospital Emergency Medicine has grown and evolved; with postgraduate qualifications and training available to clinicians from a variety of professional backgrounds, an increasing number of commissioned prehospital services alongside the voluntary agencies, and increased scrutiny and governance of practice. Our knowledge has grown too, and much of what was contained in the first edition has been superseded.

xii

This second edition has been in development for several years, hampered by the COVID-19 pandemic, when our contributors were required to focus on clinical care. However, we are now proud to share this updated and expanded ABC of Prehospital Emergency Medicine. It is our hope that this text will serve as a useful educational tool for all those in prehospital training, as well as a useful revision aid for the seasoned practitioner. We must thank the team at Wiley Blackwell, our supportive (and tolerant) families, and our expert team of authors without all of whom this project would never have happened. Finally, we would like to dedicate this text to the hundreds of prehospital practitioners who have dedicated many hundreds of thousands of hours of their own time to make the specialty what it is today. Tim Nutbeam Matthew Boylan Caroline Leech Clare Bosanko

CHAPTER 1

Prehospital Emergency Medicine

Introduction

Training in PHEM

‘Prehospital care’ is the term given to the provision of medical care outside of the hospital or alternative fixed healthcare setting. In the developed world, the provision of prehospital care is usually the responsibility of a regional ambulance or emergency medical service (EMS). A number of agencies may operate in support of the ambulance service including air ambulance charities, private ambulance companies, rescue organisations (e.g. mountain rescue, coastguard), the voluntary aid societies (e.g. St John’s or Red Cross) and volunteer immediate care practitioners (e.g. British Association of Immediate Medical Care, BASICS). Medical cover of sporting and mass gathering events, extreme and wilderness medicine, disaster and humanitarian medicine, and transfer and retrieval medicine all involve the provision of prehospital medical care.

An important advancement within prehospital care in the UK has been the recognition of PHEM as a new medical subspecialty led by the Intercollegiate Board for Training in Pre-Hospital Emergency Medicine (IBTPHEM). IBTPHEM has produced a curriculum that outlines the knowledge, technical skills, and non-technical (behavioural) skills required to provide safe prehospital critical care and transfer. Links to the IBTPHEM and the curriculum can be found in the further reading section. The key themes of the curriculum are shown in Figure 1.1. Similar prehospital training programmes exist across Europe (e.g. Germany) where they are firmly integrated into medical training and the emergency medical services. In Australasia, geography has been the driving force behind the development of retrieval medicine as a specialisation. A number of retrieval services (e.g. Greater Sydney Area HEMS) have recognised the commonality between PHEM and retrieval medicine and have moved towards delivering a combined

Prehospital emergency medicine Prehospital emergency medicine (PHEM) is a field within prehospital care. PHEM’s evolution has been triggered by the demand to meet new challenges imposed by the regionalisation of specialist medical and trauma services. Many of the critically injured or unwell patients that prove to benefit most from these new systems of care are paradoxically those less likely to tolerate extended transfer without advanced critical care support. As a result, there is a need to provide prehospital practitioners capable of advanced clinical assessment and critical care intervention at the scene of an incident, together with safe retrieval to an appropriate centre of definitive care. In most continents the enhanced skill set required to provide this level of care falls outside that deliverable by the ambulance service or its supporting bodies, and therefore requires the deployment of specially trained physician – led teams. The role of the PHEM practitioner or team is to augment the existing prehospital response, not replace it. Their function is to provide an additional level of support for those patients with higher acuity illness and injury, both on scene and during transfer. In doing so they are also well placed to educate and enhance the skills of the prehospital providers they work alongside.

ABC of Prehospital Emergency Medicine, Second Edition. Edited by Tim Nutbeam, Matt Boylan, Caroline Leech, and Clare Bosanko. © 2023 John Wiley & Sons Ltd. Published 2023 by John Wiley & Sons Ltd.

Working in emergency medical systems

Supporting emergency preparedness and response

Providing prehospital emergency medical care

Supporting safe patient transfer

Using prehospital equipment

Supporting rescue and extrication

Figure 1.1  Pre-hospital emergency medicine curriculum themes.

1

2

ABC of Prehospital Emergency Medicine

model that provides both inter-facility secondary transfer and primary prehospital retrieval. The experiences of many of these systems has helped to develop the PHEM subspecialty within the UK.

Summary PHEM is a challenging and exciting development within the field of prehospital care. This book aims to provide some of the underpinning knowledge required for effective PHEM practice.

Further reading www.ibtphem.org.uk

PA RT 1

Operational Practice

3

CHAPTER 2

Activation and Deployment Stephanie Cowan2,3, Iwan Davies2,3, and Matthew Boylan1,2 1

West Midlands Ambulance Service MERIT West Midlands CARE Team 3 The Air Ambulance Service 2

OVER VIEW By the end of this chapter you should: • Understand how emergency calls are handled and prioritised • Understand the different types of dispatch • Understand the risks and benefits of deployment by road • Understand the risks and benefits of deployment by air.

Introduction The first step in delivering high-quality prehospital care is the timely activation and deployment of prehospital resources. The initial aim is to get the right resource to the right patient in the right time frame. This process requires efficient call handling, robust call prioritisation, and intelligent tasking of resources. Prehospital practitioners may deploy to the scene using a variety of different transport modalities. The choice of modality will be determined by the system in which they work and by the nature and location of the incident.

Activation of prehospital services It is important for the prehospital practitioner to understand how emergency calls are processed and resources dispatched.

Call handling In most developed countries there is a single emergency telephone number that members of the public may dial to contact the emergency services. The emergency number differs from country to country but is typically a three-digit number that can be easily remembered and dialled quickly, e.g. 911 in the USA, 999 in the UK and 000 in Australia. In the 1990s the European Union added 112 as the Global System for Mobile Communications (GSM) approved common emergency telephone number. In the UK, emergency calls from telephone and mobile phones pass to operators within Operator Assistance Centres (OACs). OACs can now also receive emergency calls via third party

Figure 2.1  Computer-aided dispatch in the emergency control centre.

service providers such as motor vehicle collision detection systems or public access defibrillator cabinets. The role of the OAC is to connect the call to the appropriate emergency service (Police, Fire, Ambulance, Coast Guard) and provide caller and location details to the emergency service call centre (ECC). The Enhanced Information Service for Emergency Calls (EISEC) provides service subscriber details and address, termed the Caller Line Identification (CLI) for every fixed line call. For emergency calls made by mobile, the Advanced Mobile Locations (AML) system automatically sends the caller’s GPS co-ordinates via an SMS to the emergency call centre. The data then appears automatically as an incident on the dispatcher’s Computer-Aided Dispatch (CAD) screen in the ECC (Figure 2.1). At the same time, the caller is connected to a call taker at the ECC who will begin the process of call prioritisation. Location finding services such as what3words are being used by some ambulance services to augment the above systems and allow more accurate location finding.

Call prioritisation ABC of Prehospital Emergency Medicine, Second Edition. Edited by Tim Nutbeam, Matt Boylan, Caroline Leech, and Clare Bosanko. © 2023 John Wiley & Sons Ltd. Published 2023 by John Wiley & Sons Ltd.

There are several systems available by which calls can be prioritised including NHS Pathways, Advanced Medical Priority Dispatch System (AMPDS), and Criteria Based Dispatch (CBD). NHS Pathways uses a solely symptom-based approach to call assessment, 5

6

ABC of Prehospital Emergency Medicine

Table 2.1  Summary of NHS Pathways dispatch priorities and response targets Category

Colour

Type

1

Purple

2 3

4

Response target

90th percentile response target

Life threatening injury and Immediate dispatch and often autoillness, particularly cardiac allocation of nearest resource. arrest

7 minutes

15 mins

Red

Time-critical emergency calls Resources dispatched, could be diverted such as stroke patients to a Category 1 call.

18 minutes

40 mins

Amber

Urgent calls such as abdominal pains

Includes treatment by resources in their own home. Some services will interrogate Category 3 calls further.

None

120 minutes

Less urgent calls such as back pain and vomiting

Some of these patients will be given None advice over the telephone or referred to another service such as general practice or the pharmacist.

Green

Response

whereas AMPDS and CBD use a combination of symptom (e.g., chest pain, unconsciousness), specific condition (e.g. diabetes, pregnancy) or incident type (e.g. fall, road traffic accident) as prompts for assessment. Regardless of the system used, the aim is to match severity with the response time and in some systems direct patients to other community services. As an example, the priority categorisation and corresponding response targets for the NHS pathways system are shown in Table 2.1. The process of call prioritisation used by these systems is known as systematised caller interrogation and they incorporate protocolised pre-arrival first-aid instructions that are relayed by the call taker to the caller while they await the emergency response. In addition, each injury and injury mechanism can be allocated a unique code for audit purposes.

Activation of enhanced care assets Although effective in prioritising an ambulance service response, the forementioned systems have been shown to lack the sensitivity and specificity required to select calls that would benefit from enhanced prehospital emergency medicine (PHEM) intervention. To identify these cases, an additional tier of enhanced caller interrogation and dispatch criterion is required. The method by which this is achieved varies across different enhanced care services. In many services this is undertaken by active PHEM practitioners (e.g. critical care paramedics or doctors) as they are felt to be best placed to make accurate judgements about the likely need for advanced interventions. The use of non-clinical dispatchers in this role has previously been associated with high rates of over-triage, although there is some emerging evidence to suggest that the use of bespoke algorithms in combination with non-clinical dispatchers can increase tasking accuracy. One example of enhanced call prioritisation and dispatch is that used by London Air Ambulance in the UK. A dedicated Air Ambulance dispatch desk within the Emergency Control Centre is manned by an operational air ambulance paramedic. They are responsible for scanning all the incoming cases and identifying those

Mean indicator 60 mins 180 minutes

that would benefit from enhanced intervention. A set of evidencebased criteria known to be associated with severe injury are used to trigger the ‘immediate dispatch’ of the helicopter or car-based team (Box 2.1). Certain other cases undergo direct caller interrogation by the paramedic to assess whether enhanced intervention would be beneficial (Box 2.2). This is termed ‘interrogated dispatch’. The clinical knowledge and experience of the air ambulance paramedic is critical in ensuring rapid and accurate identification and prioritisation of these cases. The third form of dispatch is the crew request, which is treated as an immediate dispatch. Box 2.1  Immediate dispatch criteria (London Air Ambulance) Fall from greater than two floors (>20 feet) Fall or jumped in front of a train Ejected from vehicle Death of a same vehicle occupant Amputation above wrist or ankle Trapped under vehicle (not motorcycle) Request from any other emergency service

Box 2.2  Incident categories for interrogation (London Air Ambulance) Shooting Stabbing Explosions Road traffic collisions Industrial accidents/incidents Hanging Drowning Entrapments Amputations Burns/scalds Building site accidents Falls from height less than two floors Impalement

Activation and Deployment

7

skill set of the responders. PHEM practitioners deployed to augment the ambulance service response will usually deploy by land vehicle or by helicopter.

Deployment by land vehicle

Figure 2.2  GoodSAM instant-on-screen function (Courtesy of GoodSAM).

Obtaining accurate information from the scene of an incident is complex and represents a significant challenge to personnel interrogating emergency calls. Bystanders are often not medically trained, and the emotional effect of the incident may render them incapable of accurately describing the scene or clinical condition of the patient, causing inaccurate and delayed dispatch of appropriate resources. The time critical nature, severity of injury and scarcity of critical care teams necessitates accurate, early, and careful allocation of resources. The recent utilisation of a secure live video feed from bystander mobile phones (e.g. GoodSAM Instant-On-Screen function™ – Figure  2.2) allows visual as well as auditory triage in order to improve triage accuracy. Improved mobile and artificial intelligence technology that allow the remote assessment of vital signs and audio analysis of emotions are now being trialled to see whether they can improve the accuracy and speed of the standard interrogation process and lead to earlier deployment of enhanced care teams and less over triage.

Dispatch While the call is being prioritised by the call taker, the dispatcher is responsible for allocating appropriate resources to the incident. Most modern CAD systems have an integral automatic vehicle location system (AVLS) which will automatically populate a list of the nearest available resources. The choice of resource will depend on the location, mechanism of injury, number of patients involved, and the perceived severity of injury. Many ambulance services have moved from VHF radio to digital data transmission (e.g., Airwave in the UK) as their primary mode of communication enabling the incident details to be sent directly to the radio handset. The details are also sent directly to vehicle-mounted data terminals with integrated satellite navigation systems that will automatically plot the route to the incident. Alternative modes of dispatch include activation via a base telephone landline, mobile phone or pager system.

Many systems deploy their prehospital practitioners by rapid response vehicle (Figure 2.3). Land-based deployment is not restricted by weather or daylight hours in the same way that helicopter deployment is. They are ideal for operations in built-up urban areas as they are not limited by the need for an appropriately sized landing site. Over relatively short distances they also offer similar response times to helicopters because of the additional time taken by helicopters for take-off and landing. Response vehicles must be roadworthy. A daily vehicle check is important and should include fuel and oil levels, water coolant, screen wash, electrics, lights, and tyres (tread depth, inflation, and damage). Medical equipment should be appropriately restrained and a lockable box available for controlled drug storage. The vehicle should have visual and audible warning devices, as well as high-visibility markings. Drivers must be appropriately trained and insured for emergency response driving. Activation may be via radio or mobile phone. If activation occurs while the vehicle is mobile, the driver should pull over at the next safe opportunity before further details of the incident are taken. Progression to scene should be made rapidly but safely with the full use of visible and audible warning devices. Parking at scene will usually be under the direction of the police. If the prehospital practitioner is first on scene at a road traffic accident, the fend-off position may be used to protect the incident scene (Figure 2.4). The vehicle should be positioned approximately 50 meters back from the incident and positioned to afford maximum use of rear visual devices and reflective high-visibility markings. The front wheels should be turned in a safe direction to reduce the risk of the vehicle being pushed into the incident if another vehicle collides with it. Keys should be left in the ignition and the engine left running to prevent the battery draining flat. Once parked in a fend-off position, no one should return to the vehicle unless necessary.

Deployment of prehospital services Ambulance services may choose to deploy their resources to the scene of an incident by foot, bicycle, motorbike, car, ambulance, helicopter, or fixed wing aircraft. The decision to deploy a particular asset will be determined by the distance the asset is from the incident, the accessibility by road, known congestion, and the required

Figure 2.3  Ground-based enhanced care team. (Courtesy of the West Midlands CARE Team).

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ABC of Prehospital Emergency Medicine

Figure 2.4  Fire tenders protecting the scene in the ‘fend-off’ position. (Courtesy of Shane Casey).

Deployment by helicopter Helicopter Emergency Medical Services (HEMS) provide extended range and rapidity of advanced critical care team deployment over a large geographical area. These assets are particularly advantageous when covering remote and rural regions, allowing bypass of local hospitals, delivering patients to their definitive care site directly and quickly. They can also be utilised effectively in the urban setting where traffic congestion may limit rapid deployment by road (Figure 2.5). Deployment by helicopter provides a unique, ‘birds-eye’ view of the incident which can be useful to appreciate the complexity of a scene, access and egress routes, and any potential risk; particularly valuable at large or major incidents. Restrictions on the use of helicopter platforms occur due to environmental conditions, including poor weather conditions (high wind speeds, low cloud levels, and freezing temperatures) and an inability to identify a suitable landing site. Some aircraft are able to fly in low light conditions or hours of darkness if equipped with a Night Vision Imaging Systems (NVIS). Each service will determine the benefit of a 24-hour service, versus the added cost and risks associated with flying at night. Helicopter operations within Europe are regulated by the European Aviation Safety Agency (EASA), formerly known as JAR-OPS. Similar national regulations are in place in the USA and Australasia. EASA defines a HEMS flight as a ‘Flight by a helicopter, operating under a HEMS approval to facilitate emergency medical assistance, where immediate and rapid transportation is essential, by carrying: 1 medical personnel, 2 medical supplies (equipment, blood, organs, drugs), or 3 ill or injured persons and other persons directly involved’. The HEMS designation for flight operation is important as this allows exemptions from normal weather limits and other certain rules of air, relating to flying and landing in congested areas and special sites such as nuclear power stations, prisons, and some restricted airspaces/areas. Incidents that do not meet EASA definition of HEMS are classified as air ambulance missions and do not confer the same exemptions. Medical personnel carried on HEMS flights fall into one of two categories: 1 HEMS crew member – an individual who has been specifically trained and assigned to the HEMS flight to provide medical

Figure 2.5  Urban HEMS. (Source: Adam Calaitzis/Adobe Stock).

Figure 2.6  Example of helicopter zones of safe approach for the AW109SP.

assistance to the patient and assist the pilot during a mission with such roles as navigation or radio management. 2 Medical passenger – an individual who is carried during a HEMS flight whose primary role is patient care. No specific training other than a pre-flight briefing is required, but they must be accompanied by a HEMS crew member. During start-up and shut down, the rotors blades are less stable and more susceptible to sail. The inherent dangers of the moving rotor blades necessitate tight control of entrance and exit from the aircraft by the pilot. The crew should hold outside of the rotor disc space until a confirmatory thumbs up signal is passed from the pilot to the crew confirming that it is safe to enter the disc space. The crew will approach the aircraft in the appropriate safe direction avoiding the main hazard areas of the aircraft e.g., engine exhausts and rotor blades (Figure 2.6). It is important to note that hazard areas and direction of safe approach may differ between aircraft types and so local familiarisation is essential. When landing on scene care should be taken on sloping ground to avoid walking uphill into the rotor disc – always exit in a downhill direction under the guidance of the pilot or a HEMS crew member. Any passengers should also have received a brief from the

Activation and Deployment

pilot or a HEMS crew member before being escorted onto and off the aircraft. Take-off and landing are the most hazardous periods of a HEMS flight therefore talking and noise should be kept to a minimum during this phase unless a hazard is noted. Landing sites during daylight hours need to be twice the diameter of the rotor blades and should be flat, free of debris and clear of any wires. The surrounding area of the site needs to be considered (people, animals, potential risks) including the access and egress routes for the crew and other emergency services personnel. These requirements change substantially at night.

Tips from the field • Use of PHEM practitioners for enhanced prioritisation of emergency calls minimises over-triage • Always pull over safely before taking incident details or ­programming the sat-nav • Always carry a set of maps as a back-up in case of electronic failure • Take advantage of the bird’s-eye view of the scene afforded by helicopter deployment – assess for hazards, mechanism and ­casualty locations.

9

Further reading Avest et al. Live video footage from scene to aid helicopter emergency service dispatch: a feasibility study. Scand J Trauma Resuscitation Emerg Med 2019;27;55:1–6. Brown JB, Forsythe RM, Stassen NA, Gestring ML. The national trauma triage protocol: can this tool predict which patients with trauma will benefit from helicopter transport? J Trauma 2012;73:319–325. Lin G, Becker A, Lynn M. Do pre-hospital trauma alert criteria predict the severity of injury and a need for an emergent surgical intervention? Injury 2012;43:1381–1385. Munro S, Joy M, de Coverly R, Salmon M, Williams J, Lyon RM. A novel method of non-clinical dispatch is associated with a higher rate of critical Helicopter emergency medical service intervention. Scand J Trauma Resuscitation Emerg Med 2018;26;84:1–7. Ringburg AN, de Ronde G, Thomas SH, et al. Validity of helicopter emergency medical services dispatch criteria for traumatic injuries: a systematic review. Prehosp Emerg Care. 2009;13:28–36. Sherman G. Report on Operating Models for NHS Ambulance Trust Control Rooms in England, 2007. Manchester: Mason Communications Ltd.

CHAPTER 3

Responder Safety Clare Bosanko1,2 and Dave Dungay1 1 2

Devon Air Ambulance, UK University Hospitals Plymouth NHS Trust

OV ER VIEW By the end of the chapter you should: • Identify which items of personal protective equipment (PPE) should be part of the prehospital providers’ kit, and describe what features it should have • Know how to use risk assessment to minimise the impact of hazards

Table 3.1  Health and Safety Executive: 5 steps to risk assessment Identify the hazards Who might be harmed and how? Evaluate the risks What can be done to control the risks? Review and update procedures

• Understand the requirements of specialist PPE.

Introduction Is it safe to approach? First aid and basic life support training always starts with the premise that the rescuer should only approach a casualty if it is safe to do so. Healthcare providers working in the prehospital environment may be required to treat patients in a hazardous environment. A risk assessment will consider the potential hazards, and what can be done to mitigate these. Personal protective equipment (PPE) is the term used to describe those items worn or used to reduce risk where it cannot be entirely avoided. In recent years, infectious diseases, terrorist actions and chemical, biological, radiation, and nuclear (CBRN) incidents have highlighted the importance of PPE for the safety of both the patient and the practitioner.

Legislation Many countries have legislation requiring employers to ensure the health and safety of their employees by risk assessment and hazard management, including the use of PPE in the workplace. There is emphasis on the control of hazards to reduce harm, but where changes to working practices alone are insufficient to protect employees from exposure to the hazard, PPE should be provided to lessen the risk. In the UK, PPE provision is controlled by the Health and Safety Executive in the Personal Protective Equipment at Work Regulations, 1992. These define PPE as ‘equipment that will protect the user against health or safety risks at work’. The regulations govern

ABC of Prehospital Emergency Medicine, Second Edition. Edited by Tim Nutbeam, Matt Boylan, Caroline Leech, and Clare Bosanko. © 2023 John Wiley & Sons Ltd. Published 2023 by John Wiley & Sons Ltd.

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assessment of suitability, maintenance, storage, instruction in and use of PPE, and the responsibilities of employers and employees. In the USA, the Occupational Health and Safety Administration (OHSA) publish similar guidelines. In advance of a task being undertaken, a risk assessment identifies potential hazards, what risk they pose, the likelihood and impact of an event, and what control measures, including PPE, are in place to minimise the harm. See Tables 3.1 and 3.2. Written risk assessments and training may be provided by organisations to their employers for expected or anticipated hazards, but in the prehospital environment, where not every eventuality can be predicted or planned for, the clinician may have to undertake a dynamic risk assessment. This is a concept which originated with fire and rescue services, and describes the continuous process of identifying risk and adjusting strategies to optimise safety. In the prehospital field, risk must be balanced against the need to assess and treat a casualty in a potentially hazardous environment. The UK Joint Emergency Services Interoperability Programme suggests the ERICPD mnemonic for agreeing a co-ordinated approach with a hierarchy of control measures: Eliminate, Reduce, Isolate, Control, Personal Protective Equipment, Discipline.

Approach to a scene In advance of arriving at a prehospital incident, the clinician is likely to have some existing knowledge of the potential hazards they may face. This will allow them to consider how to approach, and whether to don any PPE. Additional information may be provided on arrival by allied providers such as fire and rescue services or the coastguard. The patient’s location and clinical needs will determine whether the clinician starts to treat them immediately or plans for them to be moved to a safer location first. Balancing a patient’s needs and their and rescuer safety can be challenging when there are conflicting priorities.

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Table 3.2  Example risk assessment for some prehospital scenarios  

Hazard(s)

Sharps

Motor vehicle collision

Risk(s)

Examples of control measures

Examples of risk mitigation & PPE

Needles from vascular access Inoculation injury devices Transmission of blood borne viruses

Training

Gloves

Easy access to sharps bin

Vaccination programme

Self-sheathing needles

Protocol for sharps injury

Vehicle debris

Personal injury

FRS* glass management

Extrication gloves, thick clothing, safety footwear, helmets

Live traffic

Struck by moving vehicles

Response vehicle ‘fend off’ position

High vis clothing

Police traffic management Pandemic

Combustible materials

Fire

Neutralising substances

Safety footwear

Pathogen infection

Healthcare worker infection

IPC** measures Training

Masks, eye protection, suits/ gowns, gloves, sleeve protectors

Training

Ballistic PPE

Onward transmission Marauding terrorist attack

Weapons

Hazardous materials

Toxic substances

Personal injury & death

Improvised weapons

Incident command

Dynamic changeable situation

Emergency services Joint Operating Principles Poisoning

Cordons

Decontamination

Contamination

Positioning uphill/upwind

Substance identification

Incident command

Antidotes

Step 1,2,3

PPE specific to the substance

*FRS = Fire & Rescue Services **Infection Prevention and Control

The role of PPE Prehospital providers work in an environment with risks from multiple sources, therefore different items of PPE are required. Gloves, masks, eye protection, sleeve protectors, and aprons guard against blood-borne or respiratory pathogens and reduce transmission of infection to and from patients. Helmets, boots and high-visibility clothing protect the wearer from injury, e.g. at the scene of a motor vehicle collision (MVC). The PPE must be designed to allow the wearer to perform the riskrelated activity with minimal limitation, but with maximum protection. Clearly, for PPE to function properly the user must be trained in how to don, wear, adjust and remove (doff) their PPE, in addition to knowledge of its limitations, how it should be stored, cared for, maintained, and disposed of.

PPE for patient contact The COVID-19 pandemic re-emphasised the requirement for clinical PPE to protect clinicians from viral transmission, both to themselves and to other patients. Healthcare workers learned to match their PPE to circumstances particularly whether an aerosol generating procedure (AGP) was undertaken. The World Health Organisation provided guidelines on recommended PPE which was adopted across countries and providers; in the UK the requirements were described according to levels, with the highest level required for AGPs being Level 3. See Figures 3.1 and 3.2.

Eye protection Eye protection protects against the risk of infection from splashes of body fluid or blood and respiratory secretions during airway management. Goggles, protective glasses, visors, and full face splash guards are all available. Eye protection should also be worn when

Figure 3.1  Level 2 and Level 3 PPE for ambulance personnel. (Source: East Midlands Ambulance Service NHS Trust).

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ABC of Prehospital Emergency Medicine

High-visibility clothing Prehospital providers working on or near a highway or in low visibility settings should wear high-visibility clothing. EN 471 is the European standard, and Class 3 garments are required for any individual likely to be working on or near motorways or dual carriageways. These offer the highest level of visibility and must incorporate a minimum of 0.80 m2 of fluorescent background material and 0.20 m2 of retro-reflective materials. Whether on a jacket or a set of coveralls this usually takes the form of two 5-cm bands of reflective tape around the body, arms and braces over both shoulders (Figure 3.3). Regulations from the USA also set minimum areas for reflective material in the shoulder area, or encircling the sleeves, consistent with the European standard.

Boots

Figure 3.2  Powered respirator hood.

there is a risk of injury to the eye from debris, such as during cutting glass or metal at an MVC. Eyewear should include side protection and should fit over prescription glasses if necessary.

Helmet Prehospital practitioners should wear head protection for all MVCs involving extrication, when working at height, during civil unrest, working on industrial sites, and in any other designated ‘hard hat’ area. Increasingly, helmets are certified to fire-fighting standards (e.g. EN443). They should have clear labelling of the wearer’s job title and an integrated visor, the standard of which is separately regulated.

Figure 3.3  Responder in PPE.

Footwear should be of the safety boot type. The European standard (EN ISO 20345:2011) demands a toe cap able to withstand impact of up to 200 joules. The Occupational Health and Safety Administration and American National Standards Institute guidance recommends minimum height of 4 inches (10.2 cm), cut/puncture and abrasion resistance, and barrier protection with chemical resistance in addition to a safety toe.

Specialist PPE There are also a number of specialist items of PPE, used by groups of providers operating in higher risk environments. PPE used in this environment forms a part of risk mitigation alongside specific training and safe systems of work.

Helicopter emergency medical services operations Prehospital practitioners involved with HEMS operations require additional PPE as a result of their aviation role (Figure 3.4). Flame-retardant flight suits made of Nomex or Kermel should be worn and are designed

Figure 3.4  HEMS Practitioner in flame-retardant flight suit.

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to protect against flash fire (4–5 seconds of flame). Most come with reflective strips, knee pads, and a selection of pockets. The addition of full-length cotton undergarments will improve the flash fire protection rating of the suit significantly by preventing excessive heat soak to the underlying skin. Flight helmets have a role in both protection of the head and communication between crew members, and are deemed compulsory for HEMS work in the UK by the Civil Aviation Authority. There is no guidance regarding hearing protection specifically for this field of work, but noise control is required consistent with industry standards.

Tactical operations Due to the increased threat and incidence of terrorism in recent years, in the UK specialist ambulance responders have been trained in tactical operations with the use of ballistic PPE. This includes Kevlar body armour and helmet (Figure 3.5). These items will protect against penetrating trauma from knives, handguns and fragmentation in the event of an explosion. Specialist tactical medical training and PPE allows care to be delivered in areas previously deemed too high risk for medical staff. These operations require specific command and control between emergency services. Recent experience has realised that first responders may find themselves in the area of threat prior to the incident being identified as terrorist related. The UK National Police Chief ’s Council have produced Run–Hide–Tell advice for persons caught in a terrorist incident (Figure 3.6). These actions are relevant for first responders that find themselves in such a situation.

Water operations Incidents near water can be classified as coastal or inland water operations. In most countries the coastguard provides water, land and air resources for the former. Following large scale flooding in the UK,

Figure 3.6  Run – Hide – Tell advice (Source: NPCC UK).

Figure 3.7  Drysuit/Flood response.

the government standardised equipment and training for inland water rescue. This categorised responders into tiers dependent on an individual’s and team’s capability. A level three responder such as a Hazardous Area Rescue Team (HART) paramedic, is trained to operate in swift water and would wear a personal flotation device (PFD) and drysuit (Figure 3.7).

Working at height and urban search and rescue

Figure 3.5  Practitioner in Kevlar body armour and helmet.

Prehospital practitioners may be required to attend patients in environments where there is a risk of a fall from height (e.g. scaffolding, cranes, pylons, hydraulic lifting platforms). PPE including harness and helmet must be rated to the appropriate standard. In the UK, rescue agencies, such as the coastguard or Fire and Rescue services, are trained in setting up access and safety systems to allow medical personnel to operate in this environment. Ambulance HART operatives will have bespoke PPE and training to allow smooth interoperability with other rescue agencies. Figure 3.8. Urban Search and Rescue is a specific function which applies to working within collapsed structures. This may require elements of working at height and working in confined space within unstable terrain. Specialist rescue teams such as UK Ambulance HART have specific training and equipment to operate in this high-risk environment.

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ABC of Prehospital Emergency Medicine

  Tips from the field • Consider the safety of yourself and your patients when approaching an incident scene. • PPE is there for your protection. Keep it in good working order and check it regularly for defects. • Some items of PPE are used less frequently and can therefore become unfamiliar. Incorporate PPE into training and ensure regular revision of unfamiliar kit. • Communication in PPE can be challenging, be aware of these limitations and adjust for them. • Liaise with other Emergency Services to assess and mitigate risks, and involve specialist teams.

Further reading Figure 3.8  PPE for operating at height.

CBRN/HAZMAT The term Chemical Biological Radiological or Nuclear incidents (CBRN) is generally used to indicate an intentional release of material and as such carries a greater threat to responders than a HAZMAT incident where release is accidental, the substance should be identifiable, and safety advice will be easier to obtain. Prompt identification that a CBRN incident is occurring and responder safety is key. In the UK responders use the Step 1–2–3 plus approach, and remain at a safe distance from contaminated areas and people. When three incapacitated people are encountered with no clear explanation responders must keep a safe distance from them, ideally up wind. See Chapter 35.

Chilcott RP, Larner J, Matar H. UK’s initial operational response and specialist operational response to CBRN and HazMat incidents: a primer on decontamination protocols for healthcare professionals, Emerg Med J 2019;36:117–123. HSE. Risk assessment. A brief guide to controlling risks in the workplace https://www.hse.gov.uk/pubns/indg163.pdf (accessed October 2020) HSE. Personal protective equipment (PPE) at work. A brief guide. https:// www.hse.gov.uk/pubns/indg174.pdf (accessed October 2020) JESIP Initial Operational Response programme guide. https://naru.org.uk/ wp-content/uploads/2014/05/NARU-IOR-A4-X-3-v8a-2.pdf (accessed December 2020) Public Health England. COVID-19: guidance for Ambulance trusts. https:// www.gov.uk/government/publications/covid-19-guidance-for-ambulancetrusts/covid-19-guidance-for-ambulance-trusts (accessed December 2020)

CHAPTER 4

Extrication Malcolm Russell1 and Rob Fenwick2 1

Emeritus Medical Director, Air Ambulance Kent, Surrey & Sussex, Clinical Governance Lead, Midlands Air Ambulance Charity, Medical Director United Kingdom Fire & Rescue Services International Search and Rescue (UK ISAR) Team, Mercia Accident Rescue Service – responding BASICS doctor 2 Consultant Nurse, Emergency Department, Wrexham Maelor Hospital, United Kingdom

Introduction and context

Table 4.1  Types of entrapment

Motor Vehicle Collisions (MVC) are common and produce a significant burden of death and morbidity worldwide. Up to 40% of casualties will be trapped following MVC, and entrapment is independently associated with mortality and morbidity. Trapped patients are more likely to have deranged physiology, more significant injuries and higher rates of significant blood loss when compared to untrapped patients. Extrication can be defined as the process of removing (or assisting the removal) of injured or potentially injured patients from vehicles following MVC. In the past decade, historical extrication practices have been increasingly questioned with greater application of an evidence-based approach. After a MVC, many patients are able to exit their vehicle unassisted or with minimal assistance. Some may be physically trapped (i.e. entangled in, or impinged by, the wreckage), medically trapped (i.e. unable to extricate due to actual or suspected injury) or be trapped by a combination of both (Table 4.1). A small number of patients may require assistance due to pre-existing disability, health problems or body habitus. If unable to self-extricate, then the patient will require some form of extrication, usually by the responding rescue team. Of those patients who require extrication, approximately 12% will be physically trapped by the wreckage requiring some element of ‘space-making’ or ‘disentanglement’; the much greater majority have the potential to be released rapidly, with appropriate medical care where indicated. Prolonged entrapment is associated with increased mortality and there are many reported cases of major trauma deaths which could be prevented by early recognition and definitive management of lifethreatening injuries. Achieving extrication quickly is therefore important and there are many variables that can be influenced by the prehospital clinician. Historically, Fire and Rescue Service (FRS) extrication strategies have been based on the paradigm of movement mitigation to avoid the exacerbation of potential spinal injuries. This approach may seem logical, but it frequently means significant time delays for the casualty (median time for a ‘traditional’ roof-off Long Spinal Board (LSB)

Type of Description entrapment Medical

No physical reason to prevent the casualty being removed from the vehicle immediately if required. Extrication required for medical reasons (e.g. pain, suspected injuries, spinal immobilisation).

Physical

Casualty trapped by the vehicle or other object, which is preventing extrication. This scenario requires mechanical intervention to create enough space to allow egress (can be as simple as opening a door, through to more complex ‘cutting and spreading’ operations such as roof removal).

Medical and physical

Where the casualty is physically trapped in the vehicle and also has medical issues to manage before they can be moved e.g. analgesia for injuries. These two components may be managed simultaneously, or one may be achieved before the other, requiring effective team leadership and coordination.

extrication is 30 minutes). During this phase, it may be difficult for the prehospital clinician to undertake a thorough assessment and /or offer meaningful intervention to patients that are trapped. Recent studies have demonstrated that spinal cord injury (SCI) is only present in approximately 0.7% of those with major trauma following a MVC. Of this 0.7% group, over half will have additional severe injuries requiring time-sensitive interventions (e.g. head and thorax). And so the balance between movement mitigation and speed of rescue has shifted. In contemporary practice a ‘careful patient handling’ approach is more commonly utilised in place of the absolute movement mitigation paradigm. This recognises that small and careful movements are permissible, to enable the benefits of a more rapid extrication from the vehicle. All patients should be moved with care, but this does not necessarily mean slowly. When considering extrication techniques, it is essential to be aware that: ●

●

ABC of Prehospital Emergency Medicine, Second Edition. Edited by Tim Nutbeam, Matt Boylan, Caroline Leech, and Clare Bosanko. © 2023 John Wiley & Sons Ltd. Published 2023 by John Wiley & Sons Ltd.

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Traditional extrication which focuses on movement mitigation typically takes around 30 minutes. Delays to thorough casualty assessment and definitive care can increase mortality and morbidity. Interventions are limited when the casualty remains trapped. 15

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ABC of Prehospital Emergency Medicine

Serious occult injuries may exist in patients with normal observations. Spinal cord injuries are rare (but are commonly associated with other severe injuries). The prehospital team should be aware of the risk of sudden deterioration at point of release (possibly due to clot disruption occurring with the inevitable movement involved) and be prepared to act accordingly. An immediate post-extrication primary survey and reassessment should always be conducted.

Team-working principles Managing patients effectively during the rescue phase can be complex and challenging, but is possible with education and training. The whole rescue team should understand the processes involved and should be able to communicate with each other in a shared language. Regular joint training is essential if this care is to be optimal as there is likely to be significant regional variation in equipment, training and techniques. A structured approach to the management of MVC patients allows consistency and efficiency on scene. Although elements of collision scenes vary, many features are shared and allow for a generic approach. The rescue team’s tasks are often divided into extrication and casualty care elements, with the senior fire officer taking overall lead informed by the senior medic present (Figure 4.1). The two functions are not necessarily provided exclusively by a single service (e.g. a firefighter will often be part of the casualty care team) and the activity of both extrication and casualty care teams should be undertaken concurrently to avoid delays. The two teams must work to a shared plan, and each has its key priorities. Effective communication, coordination and command are essential in delivering a plan that works and the team leaders should regularly liaise to ensure adequate progress and so they are both aware of the other’s constraints.

Describing the anatomy of the car

Figure 4.2  Car anatomy – key terms. Wisdomtech Services Private Limited.

front; the A-post, B-post and, in theory, alphabetically as far back as there are posts. Generally it is only the front two posts (A and B) which are referred to (Figure 4.2).

Casualty care team (and shared) tasks Safety Safety is the shared first priority for the whole rescue team. Think about safety from the perspective of yourself, the scene and the casualty. The clinical team should be trained to work in this environment and be aware of the risks involved. They should wear appropriate personal protective equipment for the environment which can include: ● ●

Vehicles vary widely in their design and structure. It is useful to be able to describe standard parts of a vehicle and standard rescue techniques with your local rescue service using shared terminology. The most common terms used in a rescue setting relate to the support structures that attach the roof. These are labelled, from the

●

● ● ●

helmet eye protection ± face visor dust mask if working inside a vehicle where glass (particularly the windscreen) is being cut coveralls (ideally flame-retardant material) boots with steel or composite toe protectors high-visibility waterproof over-jacket

Casualty care team tasks

Rapid access and assessment Treatment and monitoring

Extrication team tasks

Safety Planning

Removal of casualty from vehicle

Figure 4.1  Division of tasks at an extrication.

Vehicle stability Glass management and space-making

Extrication

● ●

●

medical protective gloves ‘debris’ gloves (e.g. leather), which can be useful when gaining access to a patient. Although the medical team should rarely be involved in handling the wreckage and in practice these gloves are rarely required. Infectious disease PPE (e.g. COVID-19) as required.

Safety of the scene is managed primarily by fire and police personnel and includes injury prevention while conducting the rescue, fire prevention (or control) and traffic management around the scene. If the clinical team is first on scene, simple measures should be carried out such as stopping traffic and removal of car keys to isolate the electrical system of a car. Be aware that un-deployed airbags may still be ‘live’ for several minutes after the ignition has been turned off. Consider too whether the vehicle is carrying any hazardous materials and act accordingly. Safety of the patient may include using a plastic shield (commonly known as a ‘tear-drop’) when tools are being used in glass management or space creation. The patient may require eye or respiratory protection. Think too about the risk of hypothermia and consider passive (e.g. blankets, bubble-wrap) or active (e.g. chemical or electrical heating systems) management methods early in the extrication to keep the patient warm; trapped patients will typically be dressed for the internal cab temperature (not the external environmental temperature) and can become cold surprisingly quickly.

Vehicle-specific hazards Modern vehicles often have multiple safety systems, some of which can present hazards to the rescue team during casualty rescue. These are managed by the fire service and are best demonstrated in practical exercises. Vehicle-specific hazards to consider include: ●

●

●

●

●

airbags and their activation units (most modern cars have multiple airbags in various parts of the car) gas struts which raise a hatchback door; these usually contain pressurised gas and fluid which may be released in an uncontrolled way if cut seat-belt pre-tensioning devices (may include pyrotechnic materials) hazardous chemicals and materials, especially if there has been a fire (i.e. products of combustion) fuel, hydrogen or electricity – depending on the vehicle’s main fuel type. Seek FRS advice.

Rapid access and assessment With safety in mind, access to the patient should be gained as early as possible, and triage carried out for treatment and extrication. A primary survey should be completed noting whether they can move all four limbs, and the degree of physical entrapment (particularly the lower legs and feet). It should be remembered that initial assessment may not detect significant (and potentially life-threatening) injuries and that physiological observations may be falsely reassuring at this point. The information regarding the clinical picture should be communicated to the clinical team leader and treatment can begin where appropriate and absolutely necessary. Significant time can be added to the extrication by low-value medical tasks and the subsequent complexity they cause (tubes, wires, etc).

17

Occupants of vehicles that have rolled are often ejected from their original positions. You may find them in the vehicle where you do not expect them (e.g. in the foot-wells, or the rear part of the passenger cell) or ejected from the vehicle itself. Ensure the surrounding area external to, and under, the vehicle is searched to avoid missing any casualties.

Extrication team tasks It is important to understand the basic approach and techniques used by the extrication team which are best learned by hands-on training with fire service colleagues in exercise scenarios.

Stability The vehicle should ideally be stabilised to prevent large movements or vibration of the patient. This can help spinal immobilisation, minimise movement of fractures (pain control) and assist haemorrhage control (clot stability) as well as minimising risk of injury to rescuers. To achieve this, the fire service may use tools including chocks and wedges, inflatable airbags and stabilisation devices. It should be noted that the small vehicular movements that stabilisation prevents is unlikely to have any meaningful clinical impact when compared to the act of full egress from the vehicle.

Glass management The glass of a vehicle is ‘managed’ where necessary to allow spacemaking (such as roof removal) and to prevent any uncontrolled breakage which can risk the rescuers and the patient. In many cases, glass may be left intact in situ. Where removal is necessary it may be broken (e.g. side windows) or cut (e.g. laminated windscreens) using dust and fragment mitigation techniques.

Space creation If the casualty requires extrication, the creation of additional space will sometimes be required. This is undertaken by the FRS, often using a range of tools to cut and/or spread the metalwork surrounding the casualty or blocking the route of egress. Simple plans are often the most effective; the more complex plans usually being associated with increased time and resource costs. Once adequate space has been created and the casualty is free, the space-making process can usually stop. In many cases of true physical entrapment, movement of only a few centimeters is all that is required to enable release. Clinical input is important throughout as clinicians will be more familiar with handling damaged limbs and can assess when the true point of release has been achieved.

Extrication methods Self-extrication Self-extrication by the patient is the favoured method of extrication and is possible for the majority of cases (regardless of age). Selfextrication should be a simple and quick process in which they exit the vehicle in a controlled manner and move to a location where injuries can be assessed fully. It has been shown to produce the smallest movements at the cervical and lumbar spine, when compared to

18

ABC of Prehospital Emergency Medicine

the other methods discussed in this chapter. Self-extrication should be assisted as required by the rescue team. It has been demonstrated that the application of a semi-rigid cervical collar can reduce the movement of the neck during the self-extrication process and therefore application may be considered by the rescue team prior to asking the patient to leave the vehicle. In this situation, the cervical collar can be viewed as an extrication-assist device and may be removed once the patient has been fully assessed or is lying on the ambulance trolley for onward transport. Decisions regarding collar removal and the degree/nature of immobilisation should be taken thoughtfully, particularly where the patient is intoxicated or has major distracting injuries, and local guidelines should be followed.

Assisted extrication methods The decision regarding which approach to use in the patient who cannot self-extricate will be based on numerous patient and environmental factors. As a basic synopsis, self-extrication can be achieved in the quickest time and with the least patient spinal movement. For the assisted methods, the time to complete these increases sequentially from snatch, rapid, B-post rip and ‘roof-off ’ due to the increasing complexity of the vehicular cutting and interventions needed. Despite the increasing time to perform, there is no significant difference in the overall patient spinal movement seen between any of the assisted extrication methods.

Figure 4.3  Rapid extrication using lateral excursion.

Snatch rescue A snatch rescue is required when there is an immediate threat to safety for the patient (e.g. fire) or if the patient is in cardiac arrest or peri-arrest. This should ideally be carried out in just a few seconds. If there are physical obstructions, then the absolute minimum of vehicular cuts should be made to achieve access. For a snatch rescue, ideally 2–4 rescue personnel will remove the patient from the vehicle, prioritising the extrication above all other considerations. Typically, the lead clinician will support the head (and airway) and others will lift/drag using whatever mechanical purchase they can reasonably achieve (e.g. limbs, clothing, patient’s belt). Once removed from the vehicle and an adequate distance away from danger, or when 360° access has been gained, movement mitigation and careful patient handling can recommence. Initiating and conducting a snatch rescue demands dynamic risk assessment, strong leadership and clear communication (e.g. ‘time critical injury’ or ‘time critical hazard’) to be effective.

Rapid extrication A rapid extrication is performed by extricating the patient laterally from the vehicle via the closest or most accessible aperture. Most frequently this will be done via the door and is most effective with four personnel. Minimal vehicular cutting should be required and the space-making may be as simple as opening the door of the vehicle as widely as possible (with or without hydraulic tools). If further space is required, removal of the B-post using hydraulic tools is normally achievable within five minutes. In the typical scenario, a rescue board is slid onto the patient’s car seat and braced to provide a horizontal platform (Figures 4.3 and 4.4). The patient is then rotated and laid down on the board before

Figure 4.4  Rapid extrication using lateral excursion with LSB in place.

being moved up along its length. During the extrication process, a member of the rescue team may apply manual in-line stabilisation (MILS) and a semi-rigid cervical collar if indicated.

B-post rip The B-post rip is a technique which can be performed rapidly and is designed to quickly create space around the casualty by removing the side of the vehicle. The rear doors of the vehicle are opened and then cuts are made through the lower and then the upper B-post (below the seatbelt pre-tensioner and at the level of the roofline respectively), which enables the entire side of the vehicle to pivot on the front hinges of the A-post. This technique can be performed quickly with minimal vehicle cutting and manipulation and removes the obstruction caused by the B-post which can hinder the rapid extrication method. This allows for greater control of the patient during the removal phase as the rescue team have better access for support and egress.

Extrication

Roof-off extrication This was historically the gold standard method of extrication following MVC. Practice is evolving, but it may still be required where access is limited and the vehicle cannot be repositioned. In addition, prehospital clinicians may come across a roof-off extrication in progress where changing strategy will result in further delay, and so it is described here for information. A LSB is slid down between the patient’s back and the back of the seat (Figure 4.5). Positioning the long board can be made easier by first sliding two ‘tear-drops’ down behind the patient’s back. The long board is then guided between these, which act as introducers, making the process easier and often more comfortable for the patient. The board is then held upright with the patient braced against it while the seat back is lowered as far as possible. Additionally, if the mechanism is still intact, the whole seat may slide back horizontally creating more space. The casualty and board together are then lowered back as far as possible. The casualty should then be moved along the length of the board in a series of small coordinated slides until fully on the board. The person providing MILS is in control and should brief the team before giving give clear, loud instructions such as, ‘Ready! Brace! Slide!’. Once the patient is lying full-length against the board, it is lowered to the horizontal position and then slid out the back of the vehicle. With very little space and multiple rescuers, think about temporarily disconnecting lines and cables. The oxygen cylinder, if oxygen is necessary during this phase, can often be placed on the board between the patient’s legs. Vascular access points, if gained, should be secured well.

Vehicle relocation It may be possible to make the process of extrication more simple by moving the vehicle. This may be to move it away from a potential obstruction, meaning that simple techniques such as self-extrication can be utilised, or could involve moving the vehicle away from potential dangers which would provide a safer environment for the patient and the rescue team.

Figure 4.5  Roof-off extrication.

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Vehicle relocation could be as simple as rolling a vehicle a short distance in a controlled manner on all its wheels, or may require different techniques and equipment e.g. using a winch to pull, or spreaders to push the vehicle carefully away from the obstructions.

Special circumstances Vehicle on its side When a vehicle is on its side, access to occupants is often initially through the hatchback/rear door, through the windscreen or (with care and fire service control) through the ‘upper’ doors. The casualty can sometimes be extricated through the rear window of the vehicle, and occasionally out through the windscreen once cut, particularly if a rapid extrication is required. Where necessary, a ‘roof fold-down’ technique can be used. In this technique, the upper supporting posts are cut (and sometimes some of the lower ones too) and the roof is laid down on the ground. This can give excellent access to the passenger cell (Figure 4.6) but can take significant time.

Vehicle on its roof When a vehicle is on its roof, there are a number of techniques that can be used to create space when it is required. Access can be made through the rear door of a rolled hatchback (Figure 4.7), through a side door, or by means of a ‘B-post rip’ (Figure 4.8). In this technique, the B-post is removed (with the rear door) by cutting it at the top and bottom. Sometimes, particularly where the roof has been crushed, further space-making is required using hydraulic rams to open up the side of the crushed vehicle: known as ‘making an oyster’. This can take considerable time but is occasionally necessary. In some scenarios the FRS may consider rolling a vehicle back upright and then tackling the problem as if the car had been found on all four wheels. The scenario of a patient suspended upside down in a seatbelt can be particularly challenging. In practice the best solution is probably any that minimises the time the patient is suspended while providing cervical spine protection as best as possible. Sometimes a firefighter can crawl below the patient’s lap area, on their hands and knees, to support the patient as they are released from their seatbelt. Keep the plan simple and use as many hands as possible to support the patient during the release. They can then usually be rapidly extricated.

Figure 4.6  Roof fold-down.

20

ABC of Prehospital Emergency Medicine

Figure 4.7  Access through rear hatch.

Figure 4.9  Access after dashboard roll.

Figure 4.8  Access after B-post rip. (Source: Malcolm Russel). Figure 4.10  Chain cabling.

Footwell entrapment Footwell entrapment is found frequently during head-on collisions and often results from relocation of the vehicle pedals and dashboard. This can severely limit access to the lower extremities of the patient and the possibility of significant injury or unrecognised haemorrhage should be considered whilst they remain trapped. The loose application of tourniquets around the lower limbs may allow for more timely application at the point of release. The exact method of space creation and the tools used to perform this technique will vary, however a ‘dashboard roll’ followed by the removal of pedals is a commonly used method of freeing the patient. Figure 4.9.

It has been reported that this method can be achieved in approximately 12.5 minutes and the overall movement associated with this approach is similar to that reported for other extrication types.

Large vehicles The principles for rescuing a casualty from a large vehicle such as a heavy goods vehicle are largely the same as for a car. The differences are most apparent in access (with the clinician often on a ladder or access platform, Figure 4.11) and removal of a casualty from height. The extrication team will often require heavier cutting and lifting equipment to deal with the heavier vehicle and its structure. This may necessitate the dispatch of specialist rescue units which can impact on extrication time.

Chain cabling Chain cabling involves attaching anchored chains or strops to the front and rear posts of the damaged vehicle and using a winch to apply traction to the vehicle (Figure 4.10). This therefore reverses the vehicle damage and forces associated with a frontal collision. In practice, the chains are often anchored to fire appliances or suitably large trees.

Impalement Impalement is an unusual event but can lead to complex extrication. With modern vehicle design, patients are rarely impaled by the structure of their own vehicle. More often they are impaled by external structures penetrating the vehicle e.g. fence railings, or by objects

Extrication

21

applying monitoring often causes delay and complicates the rescue process with the ‘spaghetti factor’ of multiple cables running from patient, through wreckage, to the monitor. It is usually better to set up a casualty reception area a few metres from the vehicle where advanced monitoring can be laid out, ready to connect, and minimise ‘attachments’ to the patient during the physical extrication.

Post-extrication care Once free, the patient should be taken to a pre-designated casualty reception area. This is typically 5–10 metres away from the crashed vehicle and can be prepared in advance with any necessary equipment. Figure 4.11  Accessing the trapped patient in a HGV cab.

carried on another vehicle involved in the collision e.g. a car crashing into the back of a static lorry carrying steel stock. In some cases the patient may be impaled and dis-impaled momentarily during the course of the collision, e.g. as the vehicle rolls over a static structure. In such cases the wound is managed as any other penetrating injury. Where the object remains embedded in, or through, the patient careful but rapid assessment and extrication planning is required. In addition to the usual primary survey, the assessment should include: ● ●

●

●

●

the likely anatomical structures affected the type and bulk of material causing the impalement and how easily it could potentially be cut the length of the object and whether it has free ends (is it still attached at either end to any structure?) the feasibility of extrication, patient management and transport if the impaling object were left in situ the risks of removing the object and the process that would be required (procedural sedation; surgical intervention; haemostasis; risk of sudden haemodynamic collapse).

Most of these unusual cases require expert management and often need early senior advice or co-response to the incident and potentially specialist rescue assets from the Fire & Rescue Service. The risks of possible courses of action should be judged and the best plan executed without unnecessary delay; indecision will never help the patient.

Treatment and monitoring While in the vehicle, treatment and monitoring should be kept simple with only the most important interventions provided, such as control of compressible haemorrhage. Whilst patients may go on to require advanced procedures, the priority of care whilst the patient remains in the vehicle should be to enable or facilitate timely extrication (e.g. adequate analgesia or sedation). If a prolonged delay is anticipated, consider administration of tranexamic acid only where IV access can be gained promptly without hampering the extrication efforts. Avoid using complex monitoring devices during the early phase of the rescue unless absolutely necessary. The process of

Summary The management of entrapped patients is challenging and complex. Clinical assessment and physiological observations are often unreliable indicators of serious injuries and priority should be given to ensuring patients are extricated promptly. Self-extrication provides the quickest approach, with the least spinal movement and should be considered the primary option for most patients. See Box 4.1. Other assisted extrication methods take longer to achieve and result in more spinal movement but may be necessary in specific circumstances. The multi-agency rescue team delivering post-MVC care should train regularly together in order to develop skills leading to safe, efficient and reproducible rescue procedures which benefit patient care. Box 4.1  Extrication key points • Prolonged extrication is associated with increased mortality • The incidence of spinal cord injuries following MVC is low (0.7%) and over half of these will have life-threatening injuries • Self-extrication is the optimal method for the majority of patients as it is faster and produces the least spinal movement • Where self-extrication is not possible, the approach should be to provide careful patient handling using the fastest technique for that situation • Interventions inside the vehicle should be minimised to avoid further delays and should focus on those which facilitate timely extrication

Tips from the field • Safety is paramount. • Delays can lead to increased morbidity and mortality. If care of the trapped patient is part of your role, train to become skilled and efficient. • Get early access to the patient(s) and agree a plan. • Occult injuries may exist in even the most ‘stable’ of patients. • Communicate with other emergency personnel and agree a target time for release. • Minimise medical interventions in the vehicle. • Be prepared to change the plan at any time. • Movement mitigation and careful handling are key principles but should not unduly delay extrication. It is usually possible to achieve both rapid extrication and careful patient handling.

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ABC of Prehospital Emergency Medicine

Further reading Calland V. Extrication of the seriously injured road crash victim. Emerg Med J 2005;22:817–821. Connor D, Greaves I, Porter K, Bloch M. Pre-hospital spinal immobilisation: an initial consensus statement. Emerg Med J 2013;30;12:1067–1069. Fenwick R, Nutbeam T. Medical versus true physical entrapment. JPP. 2018. Moss R, Porter K, Greaves I. Minimal patient handling: a faculty of pre-hospital care consensus statement. Emerg Med J 2013;30;12:1065–1066. Nutbeam T, Fenwick R, Hobson C, Holland V, Palmer M. The stages of extrication: a prospective study. Emerg Med J: EMJ 2014;31;12:1006–1008. https://doi.org/10.1136/emermed-2013-202668. Nutbeam T, Fenwick R, May B, Stassen W, Smith JE, Wallis L, Dayson M, Shippen J. The role of cervical collars and verbal instructions in

minimising spinal movement during self-extrication following a motor vehicle collision - a biomechanical study using healthy volunteers. Scand J Trauma, Resusc Emerg Med 2021;29;1:108. https://doi.org/10.1186/ s13049-021-00919-w. Nutbeam T, Fenwick R, May B, Stassen W, Smith JE, Bowdler J, Wallis L, Shippen J. Assessing spinal movement during four extrication methods: a biomechanical study using healthy volunteers. Scand J Trauma, Resusc Emerg Med 2022;30;1:7. https://doi.org/10.1186/s13049-022-00996-5. Nutbeam T, Kehoe A, Fenwick R, Smith J, Bouamra O, Wallis L, Stassen W. Do entrapment, injuries, outcomes and potential for self-extrication vary with age? A pre-specified analysis of the UK trauma registry (TARN). Scand J Trauma, Resusc Emerg Med 2022;30;1:14. https://doi.org/10.1186/ s13049-021-00989-w.

CHAPTER 5

The First Five Minutes and the Primary Survey Tim Nutbeam1 and Matthew Boylan2 1 2

Derriford Hospital, Plymouth Hospitals NHS Trust, Plymouth, UK Royal Centre for Defence Medicine, University Hospitals Birmingham, Birmingham, UK

OVER VIEW By the end of this chapter, you will understand: • The importance of your actions in the first five minutes of arriving on the scene of an incident • How to perform a focused primary survey.

The first five minutes The first five minutes are crucial in ensuring that your job goes smoothly and that your patient receives the care they need. Often on ‘tasking’ to a job, we will receive information that is useful in preparing ourselves and our team. Different systems will have a variety of approaches to enable discussion amongst the team and mental modelling of the potential job that lies ahead. This could include considering known or potential hazards, clinical interventions anticipated, support that may be required and/or likely receiving hospitals. A balance must be struck between the need for pre-briefing and the need to provide a ‘sterile cockpit’ to allow the driver or pilot to transport the team in a safe and timely fashion to the incident scene (e.g. whilst driving on blue lights). On arrival, it is imperative that the correct personal protective equipment (PPE, see Chapter 3) is worn, that we are carrying appropriate kit and that the scene is safe. Safe arrival on scene should be logged with control. Information given by dispatch is not necessarily accurate and the clinician must ensure that they are prepared to reset any preconceptions. Your arrival on scene may be the only opportunity to take a step back and appreciate the ‘big picture’ of the scene, and any implications it may have. This is the time to identify any impediments to access and egress (and formulate a plan). Do you need to request additional back-up or specialist teams? There may be an opportunity to ‘read the wreckage’; to gain an understanding of the mechanism of injury and the transfer of energy, and predict injuries. It is essential to build a rapport with those already on scene. When a flash team forms in the prehospital setting, paying

ABC of Prehospital Emergency Medicine, Second Edition. Edited by Tim Nutbeam, Matt Boylan, Caroline Leech, and Clare Bosanko. © 2023 John Wiley & Sons Ltd. Published 2023 by John Wiley & Sons Ltd.

attention to colleagues’ names and using them will help with ongoing directed communication and building effective team working. If a patient is conscious, build a connection with them too; use their name, reassure them that you are here to help and will do your best to meet their needs and, if possible, offer reassurance regarding others who may have been involved in the same incident. Building this sense of connection with the patient and a rapport with clinical and operational personnel on-scene is often overlooked; it is crucial in ensuring that a job goes smoothly and is time well spent. Following these steps, you can proceed to your primary survey.

The primary survey The primary survey is a systematic process by which life-threatening conditions are identified and immediate life-saving treatment is started. An early, thorough primary survey is critical to determining the correct clinical diagnosis and informing the subsequent clinical workflow. Initially developed for the assessment of trauma patients, the principles of thorough protocol-led assessment, combined with immediate interventions can be equally applied to the medical patient. Not every practitioner’s ‘primary survey’ will be the same – there will be variations dependent upon: ●

●

●

assessment tools availability and competency (e.g. the use of ultrasound), variations in interventions performed (e.g. many practitioners will not be in a position to perform PHEA), practitioner experience.

The  ABC system is the most commonly used in clinical practice (Table 5.1). It provides a stepwise and reproducible assessment tool which proceeds in a logical fashion, both in terms of clinical importance and anatomic region (Figure 5.1). In reality, it is unusual to perform these steps in isolation: a team approach allows for concurrent activity. However, a single clinician should take responsibility for the primary survey and ensure that all steps have been completed. The primary survey is a not, as its name implies, a one-off process; it consists of multiple surveys. Triggers for repetition of the survey include: 23

24

● ● ● ●

ABC of Prehospital Emergency Medicine

any acute change in clinical condition after an intervention, e.g. giving a fluid bolus after patient movement, e.g. transfer to helicopter patient handover.

Table 5.1   ABC

Control of catastrophic haemorrhage

A

Airway (+ cervical spine control if indicated)

B

Breathing (+ oxygen if indicated)

C

Circulation with control of non-catastrophic external haemorrhage

A

B

Airway: Head and Neck

Breathing: Chest

ing airway. A neck assessment should also identify wounds and laryngeal injury as well as factors identifying a difficult (surgical) airway. Consideration should be given to cervical spine injury and immobilisation device(s) applied as indicated. B:  Breathing assessment and intervention. Identify and treat lifethreatening injuries (Table 5.2). Administer oxygen for hypoxaemia. C: Circulation assessment and intervention. Intravenous (or intraosseous) access. Adjuncts including application of pelvic binder, reducing and splinting long bone fractures, stopping haemorrhage from wounds. Giving aliquots of a suitable fluid/product titrated to response D: Assessment of disability. Use a recognised scale e.g. AVPU/GCS, measure blood glucose and check pupil size and response. This is a good stage at which to establish an appropriate analgesic strategy. E: Exposure: this includes measurement of temperature, and, if time and conditions allow, the secondary survey. A modified primary survey for medical conditions can be found in Table 5.3. Table 5.2  Life-threatening injuries requiring intervention in the primary survey

C

Circulation: Abdomen, Pelvis, Long bones (+Chest)

Injury

Catastrophic haemorrhage

Use of assistant/haemostatics/ tourniquets

A

Actual or impending airway obstruction

Airway manoeuvres/adjuncts, suction, PHEA, surgical airway

B

Tension pneumothorax

Decompression + thoracostomy

Massive haemothorax

Thoracostomy (± drain)

Open pneumothorax

Appropriate dressing (e.g. Ashermann chest seal)

Flail chest

Analgesia, consider need for IPPV

Cardiac tamponade

Thoracotomy if imminent/actual cardiac arrest

Haemodynamic instability

Fluid resuscitation with blood products when available/ tranexamic acid

Pelvic fracture

Pelvic binder

Long bone fracture

Reduction and splinting

Decreased GCS

Airway management/IPPV if indicated

Figure 5.1  ABC as a logical process clinically and anatomically.

Other opportunities to repeat the primary survey will arise and should be taken, especially in the unstable patient. The primary survey consists of: of catastrophic external haemorrhage. When available use an assistant to control bleeding (elevation, pressure, indirect pressure, haemostatic agents) and the application of tourniquets. A: Airway assessment and intervention. The identification and resolution (or at least temporisation) of the obstructed and obstruct-

Intervention

C

: Control

D

Table 5.3  Life-threatening medical conditions requiring intervention in the primary survey Condition

Intervention

A

Actual or impending airway obstruction

Airway manoeuvres/adjuncts, suction, PHEA, surgical airway. Adrenaline in presence of anaphylaxis

B

Tension pneumothorax

Decompression + thoracostomy

Heart failure

GTN/CPAP if available

Asthma/COPD

Nebulisers (salbutamol, ipratropium bromide, Mg2+), titrate oxygen therapy

Poor tidal volumes

NIPPV, IPPV (PHEA)

Hypoxaemia

Titrate oxygen therapy

Cardiac tamponade

Pericardocentesis (± thoracotomy if imminent/actual cardiac arrest)

Haemodynamic instability

Intravenous fluids, inotropes, vasopressors

Cardiac arrest

Chest compressions

Low blood sugar

Sugar

Decreased GCS

Airway management/IPPV if indicated

Sepsis

Antibiotics

C D E

The First Five Minutes and the Primary Survey

The secondary survey is a thorough ‘top to toe’ assessment to identify any other clinical findings which the primary survey may not have revealed. The prehospital environment may not always be where this should occur. Ongoing transfer arrangements, on scene time, scene conditions and patient instability will dictate the appropriateness of this. Following the primary survey, it is important to communicate the findings to the team and provide the clinical context with a management plan. By ensuring that there is a team awareness of the plan (both from a clinical and operational perspective) you will benefit from the support of the team in delivering the plan and their perspective and advice if the plan needs to change.

25

Tips from the field • Build a rapport with the teams on scene and a connection with your patients • Practice ‘your’ primary survey until it is automatic – you (and your patient) will rely on this at times of stress • Work with your team; tasks can be delegated but one person must take responsibility for completion • Repeat the primary survey whenever an opportunity arises – patient care is a dynamic process • Failure to remove clothing is a frequent cause of missed injuries – expose and examine the whole body whilst employing hypothermia mitigation techniques.

CHAPTER 6

Airway Assessment and Management Tom Renninson1,2, Mårten Sandberg3, Tim Hooper4, Marius Rehn3,5,6, Per Kristian Hyldmo5,7, and David Lockey1,8 1

North Bristol NHS Trust, Bristol, UK Emergency Medical Retrieval and Transfer Services, Wales, UK 3 Oslo University Hospital, Oslo, Norway 4 Raigmore Hospital, NHS Highland, Inverness, Scotland 5 University of Stavanger, Stavanger, Norway 6 Norwegian Air Ambulance Foundation, Norway 7 Sorlandet Hospital, Kristiansand, Norway 8 London’s Air Ambulance. Barts Health NHS Trust 2

OV ER VIEW By the end of this chapter, you should know: • How to identify which patients need airway interventions • How to predict a difficult airway

Table 6.1  Causes of airway obstruction Anatomical level

Examples

Pharynx

Maxillofacial trauma Soft tissue swelling including the epiglottis

• The importance of basic manoeuvres in maintaining the airway

Liquid – secretions/blood/vomit

• The value of supraglottic airway devices • Indications for prehospital emergency anaesthesia • Safe practice for delivery of prehospital anaesthesia

Tongue – swelling/unconsciousness Larynx

Foreign body Oedema (e.g. allergic reactions, inflammation, trauma, burns) Laryngospasm

Introduction Ensuring a patent and protected airway has priority over management of all other conditions (with the exception of catastrophic haemorrhage). Failure to identify the need for airway intervention may be as disastrous as the inability of the prehospital care provider to perform the necessary interventions. Airway obstruction can occur at any level between the mouth and the carina (Table 6.1).

Airway assessment The awake, alert patient who can speak with a normal voice has no immediate threat to the airway. In contrast, the obtunded or unconscious patient requires rapid assessment and management of the airway. The following steps should be undertaken to fully assess the airway:

Laryngeal trauma (blunt & penetrating trauma, hanging) Subglottic/ Trachea

Look at the face, neck, oral cavity, and chest. Assess for: ● ● ●

Signs of maxillofacial or neck trauma Foreign bodies, swelling, blood, or gastric contents in the mouth Paradoxical movement of the chest and abdomen – ‘see-sawing’

ABC of Prehospital Emergency Medicine, Second Edition. Edited by Tim Nutbeam, Matt Boylan, Caroline Leech, and Clare Bosanko. © 2023 John Wiley & Sons Ltd. Published 2023 by John Wiley & Sons Ltd.

26

Swelling – bacterial tracheitis Haematoma from penetrating trauma

● ● ● ●

Accessory muscle use (head bobbing in infants) Suprasternal, intercostal, or supraclavicular recession Tracheal tug (downward movement of the trachea with inspiration) Fogging of an oxygen mask with ventilation (rules out complete obstruction)

Listen Listen for breath sounds without a stethoscope. Assess for: ●

Look

Foreign body

●

●

●

Snoring sounds caused by partial occlusion of the pharynx by the tongue Gurgling sounds indicative of fluid in the airway (e.g. secretions, blood, vomit) Inspiratory stridor reflecting upper airway narrowing and obstruction Absent breath sounds may indicate complete obstruction or respiratory arrest

Although standard auscultation of the chest for breath sounds may be valuable, ambient noise in the prehospital environment can make this difficult and potentially inaccurate.

Airway Assessment and Management

Feel Feel for expired air against your cheek whilst listening for breath sounds and watching for chest movement. If you cannot reach the patient with your cheek, use the back of your hand.

27

Table 6.2  Prediction of a difficult airway, mask ventilation, SAD insertion and cricothyroidotomy Predicting a difficult airway (HAVNOT) H  History of previous airway difficulties A Anatomical abnormalities of the face – receding jaw, large tongue, prominent teeth

Difficult airway assessment The history and examination of a patient can help to predict a difficult airway. Equally important is the need to recognise when mask ventilation or rescue interventions, e.g. supraglottic airway device (SAD) insertion, are likely to be difficult. Table 6.2 provides a summary of these factors. Identification of these features early in the assessment process may guide the level of intervention undertaken in the prehospital setting, and trigger early transfer to hospital for definitive airway management with advanced techniques (e.g. fibreoptic intubation or gas induction).

V  Visual clues – obesity, facial hair, age > 55 years N Neck immobility – short bull neck, arthritis, manual in-line stabilisation (MILS) O  Opening of the mouth 50% oxygen required Use: Moderate-severe respiratory distress or oxygenation problem Venturi mask Flow rate: 4–12 L/min dependant on venturi valve FiO2: can be set specifically with different venturi valves Venturi valves: 24% Blue, 28% White, 35% Yellow, 40% Red, 60% Green Use: Patients at risk of hypercapnic respiratory failure or paraquat poisoning

Figure 7.3  Oxygen delivery devices.

Breathing Assessment and Management

with a 28% Venturi mask and switch up or down to achieve the target saturation range. Oxygen should not be delivered via a bag–valve–mask (BVM) device to the spontaneously breathing patient as the respiratory effort needed to overcome valve resistance during inspiration and expiration increases respiratory work and may hasten respiratory muscle fatigue.

Ventilation If a patient becomes apnoeic or their ventilation is inadequate to maintain oxygenation despite supplementation, they will require ventilation. Ventilation using a BVM can be difficult and regular practice is necessary for skill retention. The self-expanding bag can give the illusion of sufficient ventilation although very little air is entering the lungs. Pay close attention to the movement of the chest and abdomen and the bag compliance during ventilation. Correct mask sizing and positioning is essential. Be aware that starting positive pressure ventilation (PPV) changes the physiology significantly. A simple pneumothorax may develop into a life-threatening tension pneumothorax. In a patient with very low venous return to the heart, for example severe sepsis or massive bleeding, the application of a positive pressure in the thoracic cavity may further impair venous return and result in loss of cardiac output. Edentulous patients pose a significant challenge that may be overcome by altering the position of the face mask (Figure 7.4). Patients with facial hair may require the application of lubricant to the face to achieve a seal. Early use of a supraglottic airway in these patients should be considered. Ventilation should only be delivered once the airway has been cleared and in combination with a jaw thrust and simple airway adjuncts. A two-person technique is recommended in order to reduce the risk of gastric inflation and improve the efficacy of ventilation.

● ●

Should not extend beyond chin Use circular masks for infants and young children

Transport ventilators

Where available a portable transport ventilator should be used during the transfer of ventilated patients. Ventilators provide more consistent ventilation than manual ventilation and allow steady targeted EtCO2 levels. Consistent normoventilation is especially important in traumatic head injury, where hypo- and hyperventilation is associated with higher mortality. Controlled mandatory ventilation (CMV) is the most commonly used mode of ventilation in the emergency setting. The respiratory rate and tidal volume are set to determine the minute volume delivered. The peak airway pressure limiting valve should be set to alert the practitioner to the development of high airway pressures. Most ventilators allow the addition of positive end expiratory pressure (PEEP) through the addition of a PEEP valve or as an integral function of the ventilator. Adding PEEP will help keeping sections of the lungs open that may otherwise collapse (atelectasis). An increased PEEP may be beneficial in patients with a pulmonary oedema. Be aware that a high PEEP may decrease cardiac output in some patients. Advanced ventilators may allow titration of oxygen concentration whereas simple ventilators are usually limited to either 100% or 50% (air mix). Suggested start values are shown in Box 7.5. It is mandatory to employ a transport ventilator with pressure alarms that will warn if the ventilator is disconnected resulting in a non-ventilated patient. Box 7.5  A guide to initial portable ventilator settings Functions

Setting

Ventilator frequency (breaths per min)

6 month–2 yrs: 20–40 2 yrs–6 yrs: 20–30

Mask size and position ● ●

Should cover face from nasal bridge to alveolar ridge Should not press on the eyes

41

>6 yrs: 12–20 Tidal volume (TV):

6–8 mL/kg body weight

Peak airway pressure (Pmax)

30 cmH2O

Oxygen fraction in inspired gas (FlO2):

0.5–1.0

Positive end expiratory pressure (PEEP):

5 cmH2O

Inspiration: Expiration ratio (I:E ratio)

1:2

● ● ● ●

Start with a high FiO2 (1.0) and titrate down Set the ventilator frequency to a rate suitable for the patient’s age Start with a low TV (6 mL/kg) and titrate to target ETCO2 If pressure mode is available, set inspiratory pressure to 20 cmH2O and adjust to obtain adequate TV and ETCO2

Patient positioning

Figure 7.4  Improving the mask seal in edentulous patients: the mask is repositioned with the caudal end of the mask above the lower lip. Head extension is maintained. (Source: Racine, S. X et al., 2010 / Wolters Kluwer Health, Inc).

A patient in respiratory distress will often not accept transport in the supine position. Elevation of the head of the stretcher or transportation in the sitting position should be considered (Figure 7.5). Sufficient analgesia is important in facilitating transportation. Patients in respiratory distress are often anxious and find it extremely uncomfortable to wear a cervical collar. Alternative measures, such as head blocks only, may be more acceptable for the patient.

42

ABC of Prehospital Emergency Medicine

Figure 7.5  Patient positioning.

Life-threatening breathing problems: trauma There are several traumatic chest injuries that pose an immediate threat to oxygenation and ventilation and require management in the prehospital phase.

Tension pneumothorax A tension pneumothorax is a potentially lethal condition which occurs when air accumulates under pressure within the pleural cavity because of a pleural defect acting as a one-way valve (Figure 7.6). The defect is usually caused by thoracic trauma but can occur in medical patients as a result of underlying respiratory disease (e.g. pulmonary emphysema, spontaneous pneumothorax). Air enters the pleural cavity on inspiration and is unable to leave on expiration. As intrapleural pressure increases there is compression and collapse of the ipsilateral lung leading to progressive hypoxia. Spontaneously breathing patients will attempt to compensate by increasing their respiratory rate and effort of breathing. Progressive respiratory distress and pleuritic chest pain are universal findings. The affected side of the chest may appear hyperexpanded, be hyper-resonant to percussion, and demonstrate reduced breath sounds on auscultation. Respiratory failure leading to respiratory arrest ensues unless treatment is initiated. Ultrasound investigation in suspected pneumothorax may be fast and valid in trained hands (see Chapter 10).

The application of positive pressure ventilation, either to support the patient’s failing ventilation or following prehospital anaesthesia, will accelerate the build-up of intrapleural pressure exponentially. Resistance to bagging or raised ventilator peak airway pressures may be the first indicator of tension pneumothorax in the ventilated patient. Oxygen saturation will decrease rapidly. Increasing pressure leads to displacement of the mediastinal structure, compression of the contra-lateral lung and compression of the heart and central vasculature leading to haemodynamic instability and cardiac arrest. Progression is rapid. Deviation of the trachea and distended neck veins in the normovolaemic patient are very rare but may be seen in imminent cardiac arrest. Their absence should not be considered a rule out finding. Once recognised, tension pneumothorax is simple to treat. In the awake patient, needle decompression with a large-bore cannula over needle device aims to convert the tension pneumothorax into a simple pneumothorax. The initial insertion site depends on local policy: either the anterior or the lateral approach. Be aware that standard intravenous cannulas may be too short, even large bore ones. The procedure is summarised in Figure 7.7. In the ventilated patient a simple thoracostomy is the preferred means of diagnosing and treating a tension pneumothorax (Figure 7.8). These must be monitored during transfer as they may occlude, and any unexpected deterioration should prompt immediate re-fingering. A routine chest drain is not indicated in the ventilated patient but in obese patients or for long transfers a chest drain may ensure patency (Figure 7.9). Prehospital chest drain insertion in conscious self-ventilating patients is rare. This requires infiltration of local anaesthetic prior to incision of the chest wall and/or use of a sedative/analgesic such as ketamine to facilitate cooperation.

Open pneumothorax An open pneumothorax is an open chest wound that communicates with the pleural cavity (Figure 7.10). If the chest wound approximates to, or is greater in size than the tracheal diameter, air will preferentially flow through the chest wall rather than the upper airway on inspiration (‘sucking chest wound’). An open pneumothorax should be obvious during inspection of the chest and immediately sealed as part of primary survey management. Commercial chest seals that incorporate a one-way valve are effective and simple to apply. Traditionally three-sided dressings were used but tend to block with blood and become fully occlusive. In the presence of multiple wounds one only (ideally the largest) needs to be vented and the remainder can be sealed. Resealing or clotting of the wounds or seal may occur and lead to the development of a tension pneumothorax. If this occurs the dressing should be lifted to allow venting and if this manoeuvre fails, decompression with a needle (or thoracostomy in a ventilated patient) should be performed.

Massive haemothorax

Figure 7.6  Tension pneumothorax.

Massive haemothorax is defined as a collection of more than 1500 ml of blood in the pleural cavity and occurs most commonly because of a vascular injury within the lung parenchyma, pulmonary hilum,

Breathing Assessment and Management

43

Needle decompression Decompression landmarks

Decompression technique 1. Prepare equipment • Skin prep • Decompression needle or wide-bore cannula • Syringe 2. Identify landmarks • Fifth intercostal space, Mid-axillary line • Second intercostal space, Mid-clavicular line 3. Clean the skin 4. Insert the needle above the lower rib 5. Aspirate during insertion with syringe 6. When air is aspirated advance cannula 7. Withdraw needle (→ hiss of air) 8. Stabilise cannula 9. Observe patient

second ICS MCL

fifth ICS MAL

• Neurovascular bundle runs below rib

Figure 7.7  Needle decompression.

Simple thoracostomy Thoracostomy technique

Figure 7.8  Simple thoracostomy.

Landmarks

1. Prepare equipment • Skin prep • Scalpel (22 blade) • Spencer wells forceps 2. Abduct arm to 30 degrees 3. Identify landmarks • Fourth-fifth intercostal space, Mid-axillary line 4. Clean the skin fourth 5. Make a 5cm skin incision along lower rib -fifth 6. Blunt dissect with forceps over lower rib ICS MAL 7. Penetrate the pleura under control 8. Enlarge hole in pleura to accept finger 9. Perform a finger sweep • In-line with male nipple • Note whether any air/blood release • Dissect over the top of lower rib • Note whether lung is up and expanded • Beware bone fragments 10. Observe patient 11. Re-finger if required

Chest drain insertion Technique

Figure 7.9  Intercostal drain insertion. (Source: Portex Ambulatory Chest Drain Set, courtesy of Smiths Medical).

1. Prepare equipment • Equipment as for simple thoracostomy • Chest drain - Adult: 28-32Fr Paed: (Age + 16)Fr • Drainage bag with flutter valve (primed) • Syringe for priming flutter valve • Suture 2. Follow procedure for simple thoracostomy 3. Insert chest drain into the incision using the finger as a guide +/- blunt introducer • Guide the tube anteriorly and apically • Ensure all drainage holes lie within the chest 4. Attach the tube to drainage bag 5. Confirm flutter valve patency • Free drainage of fluid from chest into bag • Ask patient to cough and valve leaflets should part 6. Suture drain to skin securely 7. Dress insertion site 8. Observe patient

Portex® ambulatory chest drain set

44

ABC of Prehospital Emergency Medicine

High-flow oxygen (15 L/min) and analgesia to allow spontaneous breathing is often sufficient field treatment of this condition. Large flail segments with resistant hypoxia may require prehospital anaesthesia and positive pressure ventilation. Prophylactic thoracostomy with or without drain insertion may be considered on the side(s) of the injury due to the high frequency of associated haemopneumothoraces.

Chest seal or 3-sided dressing

Other chest injuries Several other thoracic injuries may present in the prehospital phase (Box 7.6). If suspected, continued resuscitative care should be provided and the injury communicated to the receiving trauma team. Figure 7.10  Open pneumothorax. (Source: Clinical Guidelines for Operations (CGO’s) JSP-999 / Ministry of Defense / Public Domain OGL).

or mediastinum. Unexplained hypovolaemic shock in combination with unilateral (or occasionally bilateral) chest dullness and reduced air entry suggests the diagnosis. Management of hypovolaemia takes priority. Where transfer times are short, rapid movement to a trauma centre with supplemental oxygen and carefully titrated fluid resuscitation en route is required. Patients with significant respiratory compromise and those with prolonged transfer times may require chest drain insertion and/or positive pressure ventilation prior to evacuation. This is likely to be more effective at halting any ongoing bleeding than any theoretical tamponade provided by a contained haemothorax.

Flail chest A flail chest is defined as the fracture of two or more adjacent ribs in two or more places and leads to segmental loss of continuity with the rest of the thoracic cage. A small flail segment may be difficult to identify because of local muscle spasm and splinting; however, large flail segments are usually obvious as the patient tires. The flail segment moves paradoxically inwards during inspiration and outwards during expiration (Figure 7.11). Tidal volume is reduced, and ventilation compromised. Underlying pulmonary contusions add to the insult on the respiratory system and cause hypoxia. Paradoxical chest movement, hypoxia, and respiratory distress characterise a patient with a flail chest.

Inspiration

Expiration

Figure 7.11  Flail chest. (Source: Clinical Guidelines for Operations (CGO’s) JSP-999 / Ministry of Defense / Public Domain OGL).

Box 7.6  Other chest injuries Thoracic injury

Clinical features

Prehospital management

Cardiac tamponade

Penetrating chest Rule out tension wound pneumothorax Hypotension Rapid transfer to Trauma Centre Neck vein distension Thoracotomy if cardiac arrest (see Chapter 21)

Blunt aortic injury

High-energy mechanism Chest/Back pain Hypotension Differential pulses/ BP

Rapid transfer to Trauma Centre Permissive hypotension

Pulmonary contusion

Hypoxia Evidence of chest wall injury Haemoptysis

Supplemental oxygen ± ventilation Judicious fluid resuscitation Prophylactic thoracostomy if ventilated

Tracheobronchial Subcutaneous injury emphysema in neck Laryngeal crepitus Haemoptysis Air leak from wound Pneumothorax (often tension)

Supplemental oxygen If possible, defer definitive airway management Careful intubation with smaller ETT if necessary Consider primary surgical airway Selective bronchial intubation if massive haemoptysis

Myocardial contusion

Supplemental oxygen Arrhythmia management

Blunt chest injury (e.g. sternal fracture) Dysrhythmias Cardiogenic shock

Simple Penetrating or blunt Supplemental oxygen pneumothorax mechanism Monitor for tension Hypoxaemia Prophylactic thoracostomy Ipsilateral ↓ air entry if ventilated / ↑ resonance Non-progressive symptoms

Breathing Assessment and Management

Life-threatening breathing problems: medical Acute breathlessness is a common medical emergency in both adults and children, and the differential diagnosis is broad (Box 7.7). Supplemental oxygenation will improve oxygenation and hypoxic symptoms in most cases allowing transportation to hospital for further assessment. For further detail the reader should refer to Chapters 22 and 24. Box 7.7  Medical causes of acute breathlessness Airway obstruction • croup, • epiglottitis, • foreign body Acute asthma Bronchiolitis Pneumonia Exacerbation of COPD Pneumothorax Pulmonary oedema Pulmonary embolism

Tips from the field • Ask the patient ‘does your breathing feel normal?’ as a good initial indicator of pathology • Be aware of ambient light conditions; cyanosis may not be apparent in yellow street light or in the bluish glow from LED headlamps • Always check the neck, axilla, and back following penetrating chest trauma • Repeat breathing reassessment after intubation and ventilation: an occult pneumothorax may tension rapidly after positive pressure ventilation is initiated • Take care when performing a finger sweep following thoracostomy in the presence of rib fractures

45

Further reading Callahan JM. Pulse oximetry in emergency medicine. Emerg Med Clin North Am 2008:869–279. Donald MJ, Paterson B. End tidal carbon dioxide monitoring in prehospital and retrieval medicine: a review. Emerg Med J 2006;23:728–730. Jørgensen H, Jensen CH, Dirks J. Does prehospital ultrasound improve treatment of the trauma patient? A systematic review. Eur J Emerg Med 2010;17:249–253. Lee C, Revell M, Porter K, Steyn R. Faculty of Prehospital Care RCSEd. The prehospital management of chest injuries: a consensus statement. Faculty of Prehospital Care, Royal College of Surgeons of Edinburgh. Emerg Med J 2007;24:220–224. Mohrsen et al. Complications associated with pre-hospital open thoracostomies: a rapid. Scand J Trauma, Resusc Emerg Med 2021;29:166. https://doi.org/10.1186/s13049-021-00976-1 review. Racine, S. X.et al. Face Mask Ventilation in Edentulous Patients. Anesthesiology (2010)112, 1190–1193 . Roberts DJ, et al. Clinical presentation of patients with tension pneumothorax: a systematic review. Ann Surg 2015 Jun;261;6:1068–1078. Siemieniuk RAC, Chu DK, Kim LH, Gãell-Rous M, Alhazzani W, Soccal PM, et al. Oxygen therapy for acutely ill medical patients: a clinical practice guideline. BMJ 2018;363:k4169. https://doi.org/10.1136/bmj. k4169. Waydhas C, Sauerland S. Prehospital pleural decompression and chest tube placement after blunt trauma: a systematic review. Resuscitation 2007;72:11–25.

CHAPTER 8

Circulation Assessment and Management Jake Turner1,2,3 and Matthew Boylan3,4 1

Nottingham University Hospitals NHS Trust, Nottingham, UK The Air Ambulance Service, Rugby, UK 3 West Midlands Ambulance Service MERIT, Birmingham, UK 4 Royal Defence for Defence Medicine, University Hospitals Birmingham, Birmingham, UK 2

Obstructive

OV ER VIEW By the end of this chapter, you should: • Be able to define shock and its subtypes • Understand the physiology of hypovolaemic shock, arterial injury shock, the lethal diamond, and acute coagulopathy of trauma • Be aware of bleeding mimics, the pathophysiology, and presenting features

Pulmonary Embolus Tension pneumothorax

Hypovolaemic

• Be able to identify shock in the prehospital phase, and demonstrate a structured approach to the initial management • Be aware of anticoagulant reversal agents, the role of tranexamic acid, and importance of temperature control in major haemorrhage

Cardiac Tamponade Haemorrhage Dehydration

Introduction The early identification and aggressive management of shock is an important component in the resuscitation of the seriously ill or injured patient. Shock is defined as failure of the circulatory system leading to inadequate organ perfusion and tissue oxygenation. Inadequate perfusion may result from failure of the pump (the heart), inadequate circulating blood volume (absolute or relative), or obstruction to the flow of blood through the circulatory system. Traditionally shock has been subdivided into four main subtypes (Figure 8.1). In practice there is often considerable overlap, with different types of shock co-existing in the same patient. Whatever the mechanism, inadequate perfusion leads to anaerobic metabolism, lactic acidosis, and progressive cellular and organ dysfunction. Hypovolaemic shock results from inadequate circulating blood volume secondary to haemorrhage (e.g. trauma, gastrointestinal bleed) or excessive fluid loss from the gastrointestinal tract (e.g. cholera), urinary tract (e.g. DKA), or skin (e.g. severe burns). Fluid may also be lost into body tissues or compartments (so called ‘third spacing’), particularly after significant tissue trauma or inflammation (e.g. pancreatitis), worsening volume depletion. In the context of major trauma, hypovolaemic shock secondary to uncontrolled haemorrhage is the most common cause in prehospital

ABC of Prehospital Emergency Medicine, Second Edition. Edited by Tim Nutbeam, Matt Boylan, Caroline Leech, and Clare Bosanko. © 2023 John Wiley & Sons Ltd. Published 2023 by John Wiley & Sons Ltd.

46

Ischaemia Cardiomyopathy Valve dysfunction Arrhythmia

Sepsis

Cardiogenic Anaphylaxis

Poisoning

Neurogenic Shock

Distributive Figure 8.1  Types of shock. (Anaesthesia & Intensive care medicine, causes and investigation of shock, Shippey, B. (2010) / Elsevier).

practice. Bleeding may occur from damaged veins, arteries, solid organ parenchyma, and/or fractured bones. The rate of haemorrhage, presenting physiology and timeframe of deterioration, will vary depending on the source of bleeding, the patient, and other confounding factors. A number of alternative or co-existing causes of shock in trauma often complicate the clinical assessment of these patients and are discussed in more detail within the ‘bleeding mimics’ section. Progressive blood loss leads to hypovolaemia and inadequate perfusion of the vital organs. Compensation for this impaired perfusion to vital organs results in vasoconstriction of the skin, gastrointestinal tract, and musculoskeletal tissues. Anaerobic

Circulation Assessment and Management

In blunt trauma, the baroreceptor and arterial chemoreceptor-mediated reflexes predominate resulting in compensatory tachycardia, peripheral vasoconstriction, and increased minute ventilation. Tissue injury and pain are known to suppress cardiac C-fibre reflexes

BAROREFLEX

Coagulopathy

'DEPRESSOR' REFLEX

60 50 40 30 20 10 0 -10 -20 120 100

100 T.P.R.

80

H.R.

60 120

B.P.

VENESECTION 1080 c.cm.

100

FAINT

80

80 12

R.A.P.

60 CARDIAC OUTPUT (litres per min)

10

Acidosis

Figure 8.2  The lethal triad.

Hypothermia

40

HEART-RATE (Per min)

1 Arterial baroreceptors. Pressure receptors within the aortic arch and carotid sinus that respond to stretch. A decrease in circulating volume activates these receptors, resulting in an increased heart rate and peripheral vasoconstriction. This is termed the Baroreceptor Reflex. 2 Cardiac C-fibres. Mechanoreceptors within the left ventricle myocardium that respond to excessive cardiac activity in the context of hypovolaemia. Activation can result in a decreased heart rate and peripheral vasodilation. This is termed the Depressor reflex. 3 Arterial chemoreceptors. Chemoreceptors within the carotid and aortic body that are sensitised by acidosis and respond to hypoxia. Activation increases minute ventilation and suppresses cardiac C-fibre-mediated reflexes. The increased minute volume can be observed clinically as ‘air hunger’ and acts to augment venous return via the thoracic pump mechanism.

C.O.

8

8

6

6

4

4 0

4 8 12 MINUTES

RT AURICULAR PRESSURE (cm. SALINE)

The physiology of haemorrhagic shock is complex, and only a minority of patients present with hypotension and tachycardia. There are three main compensating reflexes that need to be understood when considering the physiological response to acute hypovolaemia.

TOTAL PERIPHERAL RESISTANCE CHANGE %

Shock physiology

and so the depressor reflex is seen less commonly. In penetrating trauma major vascular injury and haemorrhage may occur in the absence of significant tissue injury (which is confined to the wound tract) and/or pain. At a critical right atrial pressure, cardiac C-fibremediated depressor reflexes trigger a vagal-mediated bradycardia and peripheral vasodilation, leading to a further drop in cardiac output and worsening shock state. The physiological changes associated with the transition from baroreceptor to depressor reflex are termed the biphasic response (Figure 8.3). Arterial injury shock is the term used to describe the physiological response to sudden loss of elastic arterial diastolic recoil due to major arterial vascular injury. The associated drop in arterial diastolic pressure leads to impaired left ventricular coronary perfusion and immediate and profound cardiogenic haemodynamic instability. Patients with large defects to large arterial structures are at risk of this phenomenon, and they tend to occur more frequently in penetrating trauma, as arterial structures are more resistant to blunt shear forces due to their elastic nature. Arterial injury shock will result in a more rapid and profound haemodynamic deterioration, often resulting in cardiac arrest within minutes of injury unless early prehospital vascular control can be achieved. In comparison, exsanguination from smaller arterial, venous, solid organ or bony bleeding results in a slower physiological deterioration, with either complete or transient response to volume resuscitation.

SYSTOLIC B.P. (mmHg)

metabolism in these areas causes progressive systemic lactic acidosis and limits endogenous heat production promoting hypothermia. Acidosis, hypothermia, tissue injury, and microcirculatory hypoperfusion contribute to acute coagulopathy of trauma, leading to further bleeding. The three components of acidosis, hypothermia, and coagulopathy are known as the ‘lethal triad’ (Figure 8.2). A more recent concept of the ‘lethal diamond’ refers to the recognition that acidosis is a consequence of shock, and the sequelae of hyperkalaemia, hypocalcaemia, coagulopathy, and hypothermia are the primary concerns when resuscitating shocked trauma patients.

47

16

Figure 8.3  Changes in HR, systolic arterial blood pressure, cardiac output, peripheral resistance, and right atrial pressure during controlled haemorrhage. (Barcroft et al. 1994 / with permission of Elsevier).

48

ABC of Prehospital Emergency Medicine

It’s well established that trauma-associated coagulopathy is exacerbated by hypothermia, clotting factor consumption, acidosis, and resuscitation-associated dilution of clotting factors. However, early onset coagulopathy, referred to as acute coagulopathy of trauma, occurs via alternative mechanisms and has been shown to increase mortality in trauma four-fold. Shock and hypoperfusion seem to be a prime initiator of acute coagulopathy, resulting in activation of anticoagulant and fibrinolytic pathways. Early haemorrhage control, followed by aggressive correction of tissue hypoperfusion, is the key step in terminating acute traumatic coagulopathy.

Insult to myocardium Systolic failure

v

Compensatory vasoconstriction

v

↓Coronary perfusion

Pulmonary congestion

Bleeding mimics Although haemorrhage is the commonest cause of shock in the context of major trauma, there are several other clinical conditions that are easily attributed to haemorrhagic shock and are referred to as bleeding mimics. Recognition of bleeding mimics requires a thorough understanding of prodromal events, mechanism/kinematics of injury, and thorough primary survey  ± point of care tests to complement the clinical assessment. Bleeding mimics can occur in isolation but may also occur concurrently with one another and haemorrhagic shock, making prehospital diagnosis and resuscitation extremely challenging.

Diastolic failure

Myocardial ischaemia

Hypoxia

Progressive myocardial dysfunction DEATH

Figure 8.4  Cardiogenic shock.

Acute brain injury Catecholamine surge

α

Prodromal activity Prodromal events such as excessive exertion, illicit substances, fear, and severe anxiety can precipitate a profound sympathomimetic response to traumatic injuries, mimicking haemodynamic compromise. Such mimics will resolve with reassurance, time, and judicious anxiolysis. Incisional trauma, breach of pleural and peritoneal membranes, and blood irritation of thoracic and abdominal cavities can precipitate a profound vagal response, mimicking a biphasic C-fibremediated response to major haemorrhage. As with prodromal bleeding mimics, vagal responses will resolve with reassurance, time, and judicious anxiolysis.

Cardiogenic shock Cardiogenic shock results from myocardial dysfunction in the presence of adequate left ventricular filling pressures. Myocardial dysfunction may be the result of arrhythmia, myocardial infarction, ischaemia, contusion, or underlying cardiomyopathy. Without intervention myocardial dysfunction leads to a progressive reduction in cardiac output, reduced coronary perfusion, and worsening ischaemia (Figure 8.4).

Traumatic brain injury Traumatic brain injury and concussive forces to the brainstem can result in ventilatory dysfunction and cardiovascular compromise. Evidence suggests the cardiovascular sequalae of such injuries are secondary to surges in systemic catecholamines and sympathetically mediated local noradrenaline effects on the myocardium. The concurrent increase in ventricular afterload, hypoxia, hypercarbia, and other shock states result in myocyte injury and acute onset cardiomyopathy (Figure 8.5). Other causes of cardiogenic failure in major trauma include blunt trauma-associated myocardial contusions, coronary dissection, valvular disruption, and cytokine-mediated myocyte injury.

Peripheral vasoconstriction

β

α&β Pulmonary venous constriction

Micro-emboli Increased pulmonary capilliary pressure

Myocardial necrosis

Platelet aggregation

Damaged endothelium

Endorphins

LVF

Increased pulmonary permeability

NPO

Cardiorespiratory compromise

NPO = Neurogenic Pulmonary Oedema LVF = Left Ventricular Failure

Figure 8.5  Acute brain injury and associated cardiovascular compromise. (https://crashingpatient.com/wp-content/images/part1/sahischemia.gif, last accessed November 02, 2022.)

Distributive shock Distributive shock results from a reduction in peripheral vascular resistance caused by pathological vasodilatation. The circulating volume is insufficient to fill the dilated vascular space resulting in a state of relative hypovolaemia and systemic hypoperfusion. Septic, anaphylactic, and neurogenic shock are the most common subtypes of distributive shock. Vasodilatation in septic shock is caused by inflammatory/anti-inflammatory mediators released as part of the systemic inflammatory response syndrome (SIRS) after infection. In anaphylactic shock vasodilatation results from the antigen-induced systemic release of histamine and vasoactive mediators from mast cells. Neurogenic shock occurs when there is damage to the spinal cord above the level of T10 with subsequent loss of sympathetic outflow leading to unopposed peripheral vasodilatation. Injuries to the spinal cord above T4 may damage the cardioaccelerators and result

Circulation Assessment and Management

in profound bradycardia, compounding the vasoplegic-mediated neurogenic shock.

49

Box 8.1  The hateful eight Diaphoresis (sweaty/clammy)

Obstructive shock Obstructive shock is secondary to extracardiac obstruction to blood flow leading to impaired diastolic filling or excessive afterload. Common causes include cardiac tamponade, tension pneumothorax, and massive pulmonary embolism. Dynamic hyperinflation (gas trapping) due to excessive positive pressure ventilation in patients with severe bronchospasm may also reduce venous return (particularly in the presence of hypovolaemia), sufficient to cause an obstructive shock state. Cardiovascular compromise secondary to a tension pneumothorax is common in the positive pressure ventilated patient. In those spontaneously ventilating however, haemodynamic instability tends to only occur in extremis, and concurrent haemorrhagic shock should be strongly considered.

Assessment of circulation Lack of monitoring, poor lighting, austere environment, and unknown premorbid status make the accurate clinical assessment of shock in the prehospital arena very challenging. A thorough primary survey, understanding of prodromal events, mechanism/kinematics of injury, and familiarity with bleeding mimics are essential to identify signs of compensated and decompensated shock (Figure 8.6).

The hateful eight Compensatory mechanisms, biphasic reflex responses to hypovolaemia and unreliability of non-invasive blood pressure measurements contribute to the challenges of prehospital shock assessment. A broader clinical assessment of the patient, with correlation to the mechanism of injury, is key. This clinical assessment is more commonly known as the hateful eight (Box 8.1) and can be used to help identify patients with life-threatening haemorrhagic shock.

B

C

Respiratory rate Tachypnoea Bradypnoea

Pulses Tachycardia Bradycardia Weak/absent Blood pressure Narow pulse pressure Reduced

Figure 8.6  Clinical signs of shock.

C

D

Peripheries Cool Clammy Pale Delayed capillary refill

Level of consciousness Agitated Drowsy Coma Pupils Dilated

Pallor (tongue/lips/palms/soles) Venous collapse (variable) Low ETCO2 Air hunger Altered mental status Abnormal heart rate Hypotension

Compensated shock Hypovolaemic, cardiogenic, and obstructive shock states are all characterised by a reduced cardiac output. To offset this reduction in stroke volume and maintain cardiac output, baroreceptor-mediated sympathetic reflexes increase the heart rate and peripheral vasoconstriction, diverting blood centrally and restoring preload. This manifests clinically as tachycardia, pale and clammy skin, prolonged capillary refill time, reduced pulse pressure, and acidosis-driven increased minute ventilation (air hunger). In these early stages cardiac output and blood pressure are maintained and the shock is considered compensated (Box 8.2). Although the blood pressure is maintained, perfusion of peripheral tissues is impaired and progressive systemic acidosis results. Distributive shock states may not present with the classic skin changes or tachycardia described above. Pathological vasodilatation may prevent compensatory vasoconstriction, resulting in flushed warm peripheries in the early stages. Tachycardia may also be absent in neurogenic shock with high cord lesions, due to unopposed vagal tone. By assessing the respiratory rate, feeling the pulse rate and strength, and by looking and feeling the patient’s peripheries, the prehospital practitioner can rapidly assess for signs of compensated shock (Box 8.2). Box 8.2  Signs of compensated shock Tachycardia Tachypnoea Delayed capillary refill Pale/cool/clammy peripheries Reduced pulse pressure Poor SpO2 trace

Decompensated shock When compensatory mechanisms fail, perfusion to the vital organs becomes compromised and decompensation commences. The brain relies on a constant blood flow to maintain function, and as blood flow reduces, cognition is impaired, and confusion/agitation ensues. Presence of peripheral pulses and non-invasive blood pressure readings are unreliable in identifying decompensated shock. A full understanding of the mechanism of injury, anatomy of injury, and hateful eight physiology will guide the diagnosis and recognition of decompensation. The speed at which decompensation occurs will depend partly on the physiological reserve of the patient and the cause of the shock state. Patients in cardiogenic and distributive shock states have a limited ability to compensate and therefore are liable to

50

ABC of Prehospital Emergency Medicine

decompensate rapidly. Other confounding factors can affect the patient’s response to shock (Box 8.3), and a high index of suspicion is essential in these patient groups if shock is to be identified.

in isolation should be interpreted with caution; however, trends can be used to assess response to resuscitation more reliably. Point of care ultrasound (POCUS) can also be used to augment clinical assessment and identify hypovolaemia, sources of haemorrhage (chest/ abdomen), cardiogenic shock/cardiomyopathy, pneumothorax, and cardiac tamponade. See Chapter 10.

Box 8.3  Factors affecting the physiological response to shock Patient group Caution Elderly

Management of shock

Elderly patients have less physiological reserve, baseline haemodynamic parameters are altered, and can decompensate earlier.

Medications

Drugs such as Beta blockers will limit the ability for the patient to mount a compensatory tachycardia and lead to earlier decompensation.

Pacemakers

A pacemaker with a fixed rate will limit the ability for the patient to mount a compensatory tachycardia and lead to earlier decompensation.

Athletes/ Young

The resting heart rate may be in the region of 50 bpm. This should be taken into account when assessing for relative tachycardia.

Pregnancy

In pregnancy the normal physiological changes of pregnancy (increased plasma and red cell volume) allow the patient to compensate for longer.

Hypothermia

Hypothermia can reduce HR, RR, and BP independently making fluid titration more difficult.

A rapid and systematic primary survey, understanding of mechanism of injury/kinematics and prodromal events should identify the most likely cause(s) of shock and guide treatment (Figure 8.7). Haemorrhage is the most common cause of shock following trauma and may occur in five key sites: on the floor (external) and four more (chest, abdomen, pelvis, long bones). Evaluation of these sites forms a key part of the circulation assessment. An understanding of the trajectory of the patient’s physiological deterioration prior to the prehospital team’s arrival, and response to initial resuscitation will give an indication of the likely nature of the source of bleeding. Differentiating between compressible/non-compressible and arterial/alternative sources of bleeding can guide prehospital decision making and intervention priorities.

Haemorrhage control Compressible haemorrhage In most circumstances external haemorrhage can be controlled by the stepwise application of basic haemorrhage control techniques – the haemostatic ladder (Figure 8.8). Modern dressings come in a variety of sizes with elasticated bandages and integral pressure bars or caps to aid

Point of care tests Point of care blood gas analysis (e.g. I-Stat) will allow direct measurement of serum lactate and/or acid–base status, both of which may give an indication of impaired perfusion. Lactate measurements

C

Catastrophic junctional or limb bleeding

Dressing Tourniquet Novel haemostatic

A

Maxillofacial bleeding

B

Tension pneumothorax Massive haemothorax

Needle decompression Thoracostomy Chest drain Rapid evacuation

C

Cardiac tamponade Cardiac contusion

Thoracotomy Arrhythmia control

C

Intra-abdominal bleeding

Rapid evacuation Permissive hypotension

C

Pelvic fracture

Pelvic binder

C

Long bone fracture

Splinting Traction

D

Spinal cord transection

Definitive airway Nasal epistats + bite blocks

Immobilisation Atropine Inotropes Vasopressors

2 0.5

2

1.5

1

Potential blood loss (litres) from specific sites 0.5

Figure 8.7  Traumatic causes of shock.

Circulation Assessment and Management

51

Tourniquets Haemostatics Indirect pressure Direct pressure & Elevation Wound dressing

Figure 8.8  Prehospital haemostatic ladder.

in the application of pressure. The principle of a pressure dressing where a focal point of pressure is applied to a bleeding vessel, as opposed to an absorbing dressing where gauze is tightly opposed to a bleeding wound (Figure 8.9), is crucial to understand. Rapid and effective haemorrhage control must be a priority prehospital and may require the clinician to surgically extend the entrance of a wound to allow effective packing and pressure application to a life-threatening bleed. Where bleeding cannot be controlled by basic measures, or the environment precludes their use (e.g. military), the use of tourniquets or haemostatic dressings may be considered. These may also be used immediately in cases where haemorrhage is so severe that if not immediately controlled, would lead rapidly to death (e.g. transected carotid or femoral artery).

Tourniquets When used, tourniquets should be placed as distally as possible on the affected limb and should be tightened until all bleeding ceases (Figure 8.10). Note the time they are applied. They can often be more painful than the injury itself and judicious use of analgesia can be useful. Proximal lower limb bleeding may require the application of more than one tourniquet to achieve control. It is vital that tourniquets are reassessed regularly during the resuscitation process as they may require adjustment.

Haemostatics Haemostatic dressings are particularly useful for controlling bleeding at junctional zones (e.g. neck, axilla, groin, perineum) where tourniquets cannot be applied. A number of impregnated gauzes/ribbons and granules are available which work by two main mechanisms (Figure 8.11) to promote clotting. All must be used in conjunction with a standard dressing and direct pressure.

B. A PRESSURE DRESSING

A. NOT A PRESSURE DRESSING. THIS IS AN ABSORBING DRESSING

GAUZE GAUZE GAUZE GAUZE

Non-compressible The optimal management for non-compressible haemorrhage within the thoracic or abdominal cavity is rapid and definitive operative haemostasis. Early recognition and rapid evacuation to a major trauma center is therefore essential. A clear appreciation of the mechanism of injury, pattern of physical injury and temporal changes in physiology will allow the prehospital practitioner to identify those patients at risk. The only exception to rapid evacuation is when a massive haemothorax compromises ventilation and oxygenation, whereupon intercostal drainage should be performed prior to transfer. Re-expansion of the lung on the affected side may also control pulmonary bleeding. Patients who are imminently arresting from subdiaphragmatic/gluteal/pelvic exsanguination, or in cardiac arrest with signs of life witnessed by the prehospital team or present just prior to their arrival, may be suitable for proximal aortic control with blood product resuscitation. The use of endovascular techniques such as Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA), or resuscitative thoracotomy and thoracic aortic compression may be within the scope of some prehospital enhanced care teams. Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) involves the temporary occlusion of the aorta, using a percutaneously deployed intravascular balloon, usually inserted via the femoral artery. Two zones of aortic occlusion have been described: zone 1 – between the

Factor concentrators

Mucoadhesive agents

• Granules absorb water • Concentrates coagulation factors • Promotes clotting

• Chitosan-based products • Anionic attraction of red cells • Adherence to wound surface

e.g. Quickclot®

e.g. Celox™, HemCon™

GAUZE FOLDED GAUZE FOLDED GAUZE FOLDED GAUZE

BLEEDING

PATIENT

Figure 8.10  Combat application tourniquet® (CAT) applied to lower leg.

BLEEDING

PATIENT

Figure 8.9  Pressure dressing vs absorbing dressing.

Figure 8.11  Novel haemostatics. (Right-hand image Courtesy of Medtrade Ltd. Left-hand image Courtesy of Z-MEDICA, LLC).

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ABC of Prehospital Emergency Medicine

left subclavian artery and the coeliac artery (for the management of exsanguinating abdominal haemorrhage); zone 3 – between the caudal renal artery and the aortic bifurcation (for the management of exsanguinating pelvic or lower limb haemorrhage). REBOA has been shown in large animal studies to improve survival in noncompressible torso haemorrhage and is currently being evaluated as a bridging technique to surgical control in several prehospital services.

Musculoskeletal Following significant trauma, patients with pelvic pain, lower back pain, or physical signs of pelvic injury, and with signs of shock attributable to a pelvic injury, should have a pelvic binder applied. All obtunded, shocked patients with a significant mechanism should undergo pelvic binding. The early application of a pelvic binder will reduce bleeding through bone end apposition and limit disruption of established clots on vascular lesions. Binders should be applied to skin with a limited log roll and use of an orthopaedic scoop stretcher

(Figure 8.12). It is important to ensure the feet and knees are internally rotated and bound, to limit rotational forces at the hip joint. Excessive patient movement risks disruption of formed clot through movement of tissue and bone ends. Careful cutting of clothing to permit full exposure and the application of a scoop stretcher directly against the skin using limited (15 degree) log-rolling will lead to reduced overall movement both in the prehospital phase and in the emergency department (Figure 8.13). Care should be taken to protect the patient against hypothermia during this process. Long bone fractures should be drawn out to length and splinted in position to prevent further movement of bone ends and tissue damage. Femoral fractures may require the application of traction to overcome the contractile forces of the thigh muscles. This should be performed as part of the primary survey and may require sedation and/or femoral nerve blockade.

Maxillofacial Severe maxillofacial trauma may result in significant haemorrhage from damaged branches of carotid artery (usually maxillary artery). Airway obstruction and hypovolaemia are the main problems associated with this type of injury. After securing the airway, haemorrhage control can be achieved through a combination of facial bone splinting and intranasal balloon tamponade. The maxilla should be manually reduced and then splinted in place using dental bite blocks and a cervical collar. Epistats (Epistat II®, Xomed) inserted into each nasal cavity can then be simultaneously inflated with saline to provide balloon tamponade of bleeding and inflated until haemorrhage is controlled (Figure 8.14).

(a) First 15° log-roll

Volume resuscitation (b) Second 15° log-roll

(c) Binder tightened to achieve anatomical reduction of pelvis

Greater trochanter

Greater trochanter

Knees and feet bound

Figure 8.12  Application of a pelvic binder.

Volume resuscitation following trauma may be required to optimise haemodynamics and maintain oxygen delivery to the tissues, and limit acidosis. Blood and blood products are the resuscitation fluid of choice in traumatic haemorrhagic shock, and an increasing number of prehospital enhanced care teams are now carrying packed red blood cells  ± fresh frozen plasma/lyophilised plasma. A balanced haemostatic approach to resuscitation with warmed blood and blood products is key, and some services are administering plasma as the first resuscitation fluid of choice as early correction of acute coagulopathy may improve outcomes for haemorrhagic shock and traumatic brain injury. To minimise dilutional coagulopathy and the endotheliopathy associated with acute coagulopathy of trauma, large volumes of crystalloids should be avoided. However, it’s worth noting that for prehospital organisations not carrying blood products, the RePHILL trial has shown low volume sodium chloride resuscitation of hypovolaemic trauma patients prehospital is a safe alternative to blood products. The use of vasoactive drugs in hypovolaemic trauma patients may also worsen end organ ischaemia, hypoperfusion driven acute coagulopathy and reduce cardiac output by increasing left ventricular afterload. However, it’s worth noting that bleeding mimics such as neurogenic shock, traumatic brain injury associated cardiomyopathy and other cardiogenic causes of shock in trauma may require vasoactive support following appropriate volume resuscitation.

Permissive hypotension Permissive hypotension describes the technique of partial restoration of blood pressure after haemorrhage, prior to definitive haemorrhage

Circulation Assessment and Management

2

Scoop-to-skin packaging

15 degree logroll Back inspected First blade inserted between skin and clothes

1

Cut

Cut

3

Repeat on other side for second blade

4

Cut

53

Join scoop top and bottom

Cut 5

Top clothes removed Thermal blanket applied Head blocks and tape applied

• Collar applied (if required) • Clothes cut up seam • Scoop sized and split

Figure 8.13  Scoop-to-skin packaging.

control. The role for permissive hypotension in penetrating central/ truncal trauma has been supported by cohort studies, but in the context of blunt polytrauma, the effects of hypoperfusion on driving acute coagulopathy of trauma, concomitant head injury and the origin of the bleeding source need to be considered. The following resuscitation targets have been proposed dependent on injury profile and comorbid status: ●

●

●

Penetrating central/truncal injuries  =  Central pulse or cerebration Blunt polytrauma without TBI = SBP 80–100 mmHg (MAP 60–70 mmHg) Blunt polytrauma with TBI = SBP 100–120 mmHg (MAP 70–80 mmHg)

The level of consciousness provides a reliable and accurate end point against which volume resuscitation can be titrated. Hypotensive resuscitation should be restricted to the first hour following injury, after which normotensive resuscitation should be commenced to minimise end organ ischaemia, coagulopathy and subsequent multiorgan dysfunction and failure.

Anticoagulants and antiplatelets

Figure 8.14  Maxillofacial haemorrhage control.

The use of anticoagulants and antiplatelets will compound the rate and extent at which patients bleed in both penetrating and blunt trauma. The rapid reversal of warfarin in life-threatening haemorrhage is well established with the use of vitamin K and prothrombin complex concentrate (PCC). Some prehospital enhanced care teams carry PCC for rapid reversal in warfarinised patients prior to arrival

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ABC of Prehospital Emergency Medicine

in hospital for traumatic brain injury or life-threatening haemorrhage. Antiplatelet use is also extremely common, and reversal will be via administration of pooled platelets as part of the ongoing major haemorrhage management. Newer direct oral anticoagulants (DOAC) such as factor-Xa inhibitors and direct thrombin inhibitors are increasing in popularity as they show an improved safety profile and reduced logistical challenges than anticoagulation with warfarin. Anti-Xa agents such as apixaban, edoxiban, and rivaroxaban can be reversed with tranexamic acid and until novel reversal agents are licensed and available in the UK (Adexanet Alpha), PCC can be considered. Direct thrombin inhibitors such as dabigatran can be reversed with tranexamic acid and licensed antidotes such as Idarucizumab. Novel antidotes for DOACs are expensive and should only be used for cases of life-threatening haemorrhage in collaboration with the hospital haematologists.

Circulatory access Gaining access to the circulatory system is an essential part of the resuscitative process in the critically injured patient. In most cases access can be gained quickly by the insertion of an intravenous cannula into a peripheral vein. Standard access for fluid resuscitation is a large gauge cannula in the forearm. The dorsum of the hand, antecubital fossa, and medial ankle (long saphenous) are good alternative sites. Ideally two points of venous access in separate limbs should be obtained. Injured limbs should be avoided. Prior to insertion, a venous tourniquet should be placed no more than 10 cm away from the insertion point and sufficient time allowed for it to work. Care should be taken to secure cannulae and intravenous lines with dressings, bandages, and tape prior to any patient movement. There are situations where peripheral intravenous access may be difficult or even impossible (Figure 8.15). In these cases intraosseous access should be considered. Any drug, fluid or blood product that can be given intravenously can be given via the intraosseous route. In addition to the standard Cook® needle there are a number of mechanical intraosseous devices that allow needle insertion into both adult and paediatric patients, e.g. EZ-IO® intraosseous infusion

Manual cook needle (Cook® medical)

FASTI® and FAST responder® (Pyng medical)

Intraosseous devices

EZ-IO® (Vidacare)

Bone injection gun™ (Waismed)

Figure 8.16  Intraosseous devices. (Top left-hand image – Permission for use granted by Cook Medical Incorporated, Bloomington, Indiana. Top right-hand image – Permission for use granted by Pyng Medical. Bottom left-hand image – Permission for use granted by Vidacare. Bottom right-hand image – Permission for use granted by Waismed.)

system and the Bone Injection Gun™ (Figure 8.16). Specific sternal intraosseous devices (e.g. FAST Responder™ sternal intraosseous device) are also available and can be useful in patients with limb polytrauma. Standard insertion sites are shown in Figure 8.17. In small infants and neonates, the distal femur has also been advocated as a suitable alternative insertion site. The humeral head and sternal insertion sites permit flow rates five times higher than those in the tibia. Care should be taken to splint limbs and secure needles with commercial stabilisers or dressings to prevent dislodgement. All intraosseous needles require an initial flush prior to use. Infusion should then be performed using a bolus technique with a 50-mL syringe attached to a three-way tap and fluid bag (Figure 8.18). Monitor for extravasation particularly in infants as there is a risk of compartment syndrome if this is not recognised. Some prehospital systems utilise large bore peripheral catheters (Rapid Infusion Catheters®) or central venous catheters (e.g. MAC™ or Swan Sheath, Arrow® international) to deliver

Poor technique e.g. Infrequent user Vein damage e.g. IV Drug abuse

Entrapment e.g. limited access

Venous shutdown e.g. shock, cold

Difficult intravenous access

Limb injuries e.g. amputations

Extremes of age e.g. elderly, infants

PPE e.g. CBRN Environment e.g. Low light

Figure 8.15  Difficult intravenous access.

Circulation Assessment and Management

55

Humeral head • Adduct arm to body and flex elbow to 90° • Internally rotate arm so hand over umbilicus • Greater tubercle now lies anterior on shoulder • Insert needle perpendicular to bone • Splint limb to side to prevent dislodgement Proximal tibia Adult • One finger breadth medial to tibial tuberosity Child • One finger breadth below and medial to tibial tuberosity • Two finger breadth below patella and one finger medial Distal tibia Adult • Three finger-breadths above tip of medial malleolus Child • Two finger-breadths above tip of medial malleolus

Figure 8.17  Common intraosseous insertion sites.

Figure 8.19  Central venous access with a large-bore subclavian line.

Calcium chloride Calcium plays an important role in platelet adhesion and coagulation, as well as contractility of myocardial and smooth muscle cells. Hypocalcaemia is present in up to 60% of major trauma patients (89% after blood product administration) and is associated with increased mortality. Serum calcium is chelated by the citrate used as a preservative in blood products and so calcium replacement is essential in all patients undergoing prehospital blood transfusion. Calcium should be administered early in patients suspected of suffering haemorrhagic shock.

Hypothermia

Figure 8.18  Blood administration via an intraosseous needle.

high-flow, large-volume prehospital transfusion of blood products to patients with critical hypovolaemia (Figure 8.19). The subclavian vein offers better anatomical access than other routes and remains patent even during cardiac arrest or critical hypovolaemia. The femoral veins are a viable alternative but may collapse in severe shock and present a higher risk of arterial puncture, infection, and thrombosis.

Hypothermia forms part of the lethal triad and will exacerbate acidosis, coagulopathy, and cause further bleeding if ignored. It is essential that the patient is always protected from the environment, with exposure for critical interventions only. Various thermal blankets and wraps are available – some with integral warming pads and access ports. Intravenous fluids should all be warmed and vehicle heaters should be turned on during transfer.

Triage All shocked trauma patients should be triaged to a major trauma center with an ability to deliver massive transfusion and rapid transfer to theatre. Some systems allow prehospital alerting for massive transfusion in order to minimise delays to receiving blood products.

Medical causes of shock Other considerations Tranexamic acid Tranexamic acid acts to limit the hyperfibrinolysis seen in the acute coagulopathy of trauma. The CRASH 2 trial showed that the administration of tranexamic acid within 3 hours of injury to trauma patients with, or at risk of, significant bleeding reduced the risk of death from haemorrhage, with no apparent increase in fatal or nonfatal vascular occlusive events. The most benefit is seen if given within 1 hour of injury.

Figure 8.20 summarises the possible causes of shock in the medical patient and highlights the key interventions. The presence of jugular venous distension is suggestive of either cardiogenic or obstructive shock. The lung fields will be clear in obstructive shock and congested in cardiogenic shock due to left ventricular failure. Absence of jugular venous distension is suggestive of either hypovolaemia or distributive shock. The history and examination will be key in determining the likely cause. Medical causes of shock will be dealt with in more detail in Chapter 22 on medical emergencies.

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ABC of Prehospital Emergency Medicine

Prehospital intervention IV crystalloid

Hypovolaemic

Obstructive

Cardiac tamponade

Pericardiocentesis

Pulmonary embolus

Oxygen, Thrombolysis if peri-/cardiac arrest

Tension pneumothorax

Needle decompression, Finger thoracostomy

Arrhythmia Cardiogenic

Distributive

Infarction

Anti-arrhythmic drugs, DC cardioversion, Pacing Aspirin, Thrombolysis, Transfer for revascularisation

Heart failure

Nitrates, CPAP, Diuretics

Anaphylaxis

Remove allergen, Adrenaline, Antihistamine, Steroid

Sepsis

Sepsis six-including antibiotics, IV fluid

Tips from the field • The integration of mechanism of injury, anatomy of injury/primary survey, and hateful eight physiology is needed to determine the presence of haemorrhagic shock • Cerebration is a valuable and reliable measure of physiological cardiovascular compensation in the shock state • There are a wide variety of bleeding mimics, but a consideration of injury profile, physiology and use of point-of-care tests can help to diagnose these • Non-invasive blood pressure readings can be unreliable and provide false reassurance, and the heart rate can be low or high in profound hypovolaemia • The humeral and sternal intraosseous sites allow the best flow rates, and the distal femur is a useful site for small infants and neonates • Application of a pelvic binder and splinting of long bone fractures should be undertaken as part of the primary survey

Figure 8.20  Medical causes of shock.

Further reading Barcroft H, Edholm OG, Mcmichael J, Sharpey-Schafer EP. Posthaemorrhagic fainting: study by cardiac output and forearm flow. Lancet 1944 Apr 15;243(6294):489-491. Bickell WH, Wall MJ, Pepe PE, Martin RR, Ginger VF, Allen MK, et al. Immediate versus delayed fluid resuscitation for hypotensive patients with penetrating torso injuries. N Engl J Med 1994 Oct 27;331;17:1105–1109. Brohi K, Cohen MJ, Davenport RA. Acute coagulopathy of trauma: mechanism, identification and effect. Curr Opin Crit Care 2007 Dec;13;6:680–685. Little RA, Kirkman E, Driscoll P, Hanson J, Mackway-Jones K. Preventable deaths after injury: why are the traditional ‘vital’ signs poor indicators of blood loss? J Accid Emerg Med 1995 Mar;12;1:1–14. Spahn DR, Bouillon B, Cerny V, Duranteau J, Filipescu D, Hunt BJ, et al. The European guideline on management of major bleeding and coagulopathy following trauma: fifth edition. Crit Care 2019 Mar 27;23;1:98. Wiles MD. Blood pressure in trauma resuscitation: ‘pop the clot’ vs. ‘drain the brain’? Anaesthesia 2017;72;12:1448–1455.

CHAPTER 9

Prehospital Monitoring Tim Harris and Peter Shirley Royal London Hospital, London, UK

OVER VIEW By the end of this chapter you should: • Develop an understanding of the common monitoring modalities used in prehospital care • Develop an awareness of the limitations of common monitoring modalities • Understand how the prehospital environment and mode of transport may affect monitoring

Introduction The role of monitoring is to provide a real-time visual display of a patients’ physiology and to alert the clinician when this falls outside predetermined limits. The prehospital environment presents a challenge when assessing, treating and monitoring patients. This, and the need for rapid assessment, often leads to compromise between what is desirable and what is practical. Indeed, there are situations where the time taken to place monitoring is of greater risk than benefit to a patient – for example if a patient with a penetrating chest injury is conversant and close to definitive care then the requirement for rapid transfer overrides the desire for full accurate physiological measures.

Prehospital monitoring The same physiological variables should be monitored as in the resuscitation room: pulse, oxygen saturation, ECG, blood pressure, respiratory rate, conscious level, temperature, and end-tidal carbon dioxide. In patients transferred between clinical treatment areas, invasive blood pressure, central venous pressures, and urine output may also be monitored in transit. The clinician needs to make an active choice of which variables to monitor and what alarm limits to set (Figure 9.1). A written record should be maintained in longer transfers, both to assist in detecting trends and to monitor responses to treatment. It is important for the prehospital practitioner to recognise how these physiological variables can be affected by the prehospital

ABC of Prehospital Emergency Medicine, Second Edition. Edited by Tim Nutbeam, Matt Boylan, Caroline Leech, and Clare Bosanko. © 2023 John Wiley & Sons Ltd. Published 2023 by John Wiley & Sons Ltd.

Figure 9.1  Modern multimodality monitors allow different physiological variables to be displayed simultaneously on a single screen. Assigning different colours to different physiological variables aids clarity and safety.

environment and/or transportation. Significant fluid shifts may occur during take-off and landing on retrieval flights, altering invasive vascular monitoring. The vibration/motion in moving ambulances or helicopters may render non-invasive blood pressure virtually redundant. Movement during patient positioning and transportation may stimulate catecholamine surges leading to rises in pulse and heart rate by over 10%. Physical characteristics such as ambient light, temperature, body fluids, mechanical fluids, aircraft safety, and movement may all affect the use of monitoring. Back-up equipment, familiarity with the limits of the kit, and trouble-shooting skills are therefore essential.

The human–equipment interface Clinicians routinely respond to clinical cues, alarms, and alerts that occur during patient care. They appraise the situation, assess the significance of these warnings, and make a decision to either intervene or continue monitoring the situation. They are also aware of the subtle indicators of normal function that are in the background. With experience these become familiar and can be a significant 57

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ABC of Prehospital Emergency Medicine

○

Aircraft power supply: able to use aircraft auxiliary power supply Battery power supply: exchangeable internal battery and external connection ○ Back-up battery: internal battery covering external power failure ○ No change in function while power supply changed 6 Function indication ○ Normal function indicated ○ Abnormal function identified promptly both visually and audibly ○ Fail-safe loss of function reverts to least hazardous condition ○ Maintain all functions in all environments ○ Accessible memory 7 Reliability ○ High reliability, low failure risk 8 Training programme ○ Supplied with complete training package. 9 Physically robust ○ Knock and crack proof ○ Water-resistant ○

The structured approach to monitoring

Figure 9.2  All monitoring equipment needs to be easily accessible and visible.

adjunct to monitoring. Trained and experienced practitioners are alerted to potential problems before alarms trigger and will be able to act accordingly. Noticing the change in sound as a ventilator becomes disconnected, the experienced practitioner would respond before disconnection alarms were triggered and well before a change in the patient’s vital signs. Alarm fatigue is a significant safety concern and is avoided by setting the alarm triggers to those that require (a change in) treatment. Monitoring equipment needs to be easily accessible and visible during transfer (Figure 9.2). Box 9.1 summarises the ideal characteristics of out of hospital monitoring equipment. Box 9.1  Ideal characteristics of prehospital monitoring equipment 1 Loud and visible alarms ○ Alarms should be visible and audible against background noise levels 2 Large and clear illuminated display ○ The display should be visible at distance, in sunlight, and be capable of displaying ECG, arterial oxygen saturation, non-invasive blood pressure, two invasive pressures, capnography, and temperature 3 Simplicity of operation ○ Easily manipulated, intuitive controls ○ Recognised modes and settings ○ Immediately available consumables ○ User-friendly, interchangeable with universal connections 4 Equipment characteristics ○ Complies with relevant regulations and standards (medical and aviation) ○ Lightweight, tough, portable with low centre of gravity, easily fixed, held, and moved ○ Ability to store and display, print out or transfer data to highlight trends and provide a medico-legal record 5 Power supplies ○ Multiple and independent ○ Mains power supply: worldwide voltage and frequency

The best monitor remains the clinician. Initial assessment may occur when the patient is trapped or only partially visible to the clinician, and needs to be regarded as baseline monitoring. As the environment becomes more permissive and access to the patient improves, so too will the level of monitoring that may be employed. The application of monitoring should follow and be an integral part of the  ABCDE primary assessment. A structured approach to assessment allows for a rapid accurate response and minimal error under pressure.

Airway Clinical assessment is made for the adequacy of ventilation, airway obstruction, and risk of aspiration. If the airway is protected with a cuffed endotracheal tube, its length at the lips and cuff pressure are noted.

Breathing Monitoring begins with noting the misting of the oxygen mask or tracheal tube and chest movement.

Respiratory rate This is arguably the most sensitive detector of cardiovascular compromise and its value is often minimised by inaccurate measurements. If counted manually, at least 15 seconds should be used to calculate the minute rate. There remains no agreement on what constitutes a normal respiratory rate; however, most studies suggest a range of 14–24 breaths per minute. It is measured on most monitors by the delivery of a small AC current via ECG leads I (adults) or II (neonates, infants). The changing thoracic impedance with respiration is then used to calculate the rate. This system requires 30 seconds to ‘learn’ a rate.

Pulse oximetry This provides a non-invasive, continuous read out of oxygen saturation. The technology measures the absorption of red (660 nm) and infrared light (940 nm) (Figure  9.3). Oxy- and deoxyhaemo­globin have different absorptions and the proportion of each is measured around 50 times per second. The system requires pulsatile blood flow

Prehospital Monitoring

(a)

Infrared (940 nm) diode

Red (660 nm) diode

Extremity (finger, toe or nose) Light excluding enclosure Cable

10

Red (660 nm)

Infrared (940 nm)

ABSORPTION

(b)

Photodetector

59

prehospital care, as measured end tidal carbon dioxide (ETCO2, normal range 35–45 mmHg, 4.0–5.7 kPa) levels and waveform analysis provide information on confirming tracheal intubation, respiratory rate, airways/endotracheal tube obstruction, ventilator disconnection/leak, muscle relaxation, cellular function, and cardiac output (Figures 9.4 and 9.5). The waveform may display ETCO2 as a function of expired volume or (more commonly) time. It is little altered by motion/vibration, and interpretation provides real time data, as opposed to the delay associated with oximetry. Its use is considered standard of care for intubated patients.

HbO2

Hb

0.1 600

700 800 900 Wavelength (nm)

1000

Figure 9.4  Normal (rectangular) capnography waveform.

Figure 9.3  Pulse oximetry.

to obtain reliable readings and loses accuracy at readings below 70%. Values are affected by vibration, patient movement, poor peripheral perfusion, external light sources, severe anaemia (below 5 g/dL) and false fingernails. Most oximeters use two wavelengths and can only distinguish haemoglobin and oxyhaemoglobin. If carboxyhaemoglobin is present they will not identify this and therefore underestimate the degree of hypoxia. Conversely elevated methaemoglobin and sulfhaemoglobin levels will show low saturation levels for a given arterial oxygen tension. Multiwavelength oximeters allow carboxy- and methaemoglobin levels to be assessed. Several probe types are available for different body sites. The ear is most dependent on mean perfusion pressure and the finger on sympathetic tone. Reflectance oximetry using three LEDs and two photodetector rings is able to offer more reliable information in low signal-to-noise environments. It is essential to remember there is a time lag (15–30 seconds) between blood being oxygenated at the lungs and its arrival at the monitored site (pulse oximetry lag). The pulse oximetry reading therefore represents the state of lung oxygenation 15–30 seconds in the past. Vasoconstriction in shock or hypothermia will increase this time lag significantly (up to 2–3 mins). Action must be taken to improve oxygenation as soon as saturations are seen to drop and before the steep part of the oxygen dissociation curve is reached (i.e. before SpO2  15 mmHg, purple 95%, and specificities of  >95%. The sensitivity for ruling out pneumothorax exceeds the performance of CXR. The lower sensitivities reflect the common CT finding of small and arguably clinically insignificant pneumothoraces in patients with traumatic injuries. Pneumothoraces are more likely to be missed on USS if small and apical or basal.

Figure 10.4  Chest ultrasound: a pleural effusion above the diaphragm (D).

Method

A high-frequency linear transducer is best, but as demonstrated in Figure 10.3, a curvilinear transducer can be used: placed in the longitudinal plane and moved caudally down the chest wall, starting immediately inferior to the clavicle and moving down to the sixth or seventh intercostal space in the mid-axillary line, sampling in each one. The ribs are identified as echogenic structures with an acoustic shadow. The pleura lies 0.5 cm posterior to the rib margins.

Pleural effusion Pleural effusions (e.g. blood, exudate or transudate) appear anechoic on ultrasound (Figure 10.4). USS has sensitivity of 40–95% and specificity of > 95%, approaching that of CT. It is better than plain chest film or clinical assessment for identifying pleural fluid, especially in the supine patient. The large range of sensitivities reflects the operator skill level, time taken to perform the scan (and how much of the costophrenic recess was visualised) and the reference standard. Clinically significant haemothorax or pleural effusion is rarely missed by USS.

Method

In the supine patient the chest should be assessed for pleural effusion using the curvilinear transducer as part of the extended focused assessment with sonography in trauma (eFAST) examination. The transducer should be moved cranially one or two intercostal spaces from the position used for views of Morrison’s pouch (hepatorenal space) and the splenorenal angle in the mid-axillary line. The diaphragm appears as an echogenic line moving with respiration – pleural effusion appears as an anechoic area above the diaphragm.

Lung consolidation Consolidation may be due to lung oedema, bronchopneumonia, pulmonary contusion or lobar atelectasis. The non-aerated consolidated lung tissue allows transmission of ultrasound with minimal attenuation so changing the USS image from chaotic scatter pattern to a hypoechoic tissue structure akin to the appearance of the liver (Figure 10.5). Echogenic circular or tubular structures may be seen within the consolidated tissue, representing air-filled bronchi (ultrasound air bronchograms).

Alveolar interstitial syndrome

Figure 10.3  Chest ultrasound: comet tail artefacts (*) suggesting no pneumothorax is present.

The sensitivity of the USS detection of pulmonary oedema in the setting of a dyspnoeic patient is up to 100% and specificity as high as 92%. An increased amount of fluid appears first in the interlobular septae (interstitial), and subsequently the alveolar spaces. The appearance is of vertical ‘ultrasound lung comets’ or B-lines. These move with respiration and tranverse the full field of the ultrasound screen. They increase in number with increasing lung water and when multiple (>2 per intercostal space) are pathological (Figure 10.6). Multiple B-lines 7 mm apart are caused by thickened interlobular septa, characteristic of interstitial oedema. B-lines 3 mm apart, or closer, suggest alveolar oedema. B lines may also be caused by pulmonary fibrosis.

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ABC of Prehospital Emergency Medicine

●

●

Figure 10.5  Chest ultrasound: consolidated lung (hepatisation). (Courtesy of Dr Dharmesh Shukla.)

Figure 10.6  Chest ultrasound: multiple comet artefacts suggestive of pulmonary oedema.

C – Assessment of circulation USS can be used to assess the three components of the circulatory system: the heart, blood volume and blood vessels. A focused echo will give valuable information about the heart and volume status in cases of cardiac arrest and shock. An eFAST scan may be useful in identifying intrathoracic or intraperitoneal free fluid (e.g. blood) in the hypovolaemic patient. Blood vessels may also be imaged directly to facilitate intravenous line placement.

Focused echo Knowledge of cardiac performance and chamber size can be critically important in the assessment of cardiac arrest and shock. The key questions answerable by focused echo are: ● ●

Is there any cardiac activity? Is there a pericardial effusion/tamponade?

Is there evidence of pressure loading of the right ventricle suggestive of massive pulmonary embolism? Is there evidence of hypovolaemia?

Echo has been proposed as a prognostic tool for cardiac arrest. The combination of asystole on ECG and no cardiac activity on USS confirms a dismal prognosis. Rarely the echo may show ventricular fibrillation with the ECG suggesting asystole. Data suggests that the absence of any echocardiographic mechanical activity during PEA (pulseless electrical activity) arrest is associated with a lower (but not zero) return of spontaneous circulation and rate of survival than cases displaying mechanical cardiac activity (so called ‘pseudo-PEA’). However absence of cardiac motion on echo is not sufficient grounds to cease resuscitation. Echo is not a priority for shockable cardiac arrest. Pericardial tamponade is a clinical diagnosis. The identification of a pericardial effusion is relatively easy, but identifying echo tamponade takes skill and experience. In the hypotensive trauma patient an effusion is likely to be causal. In medical patients in extremis any collapse of the right ventricle as it fills in diastole (‘diastolic collapse’) or paradoxical movement of the septum (into the left ventricular cavity) is evidence of tamponade. Systolic atrial collapse is the most sensitive sign but specificity is only around 50%. If the IVC is 50% with respiration, tamponade is unlikely. Cardiologists assess the changes in blood flow across the mitral valve with  >25% inspiratory variation diagnosing (echocardiographic) tamponade. The right ventricle should appear to have a diameter of 0.6–0.8 of the left ventricle. If the right ventricle is acutely pressure overloaded and bigger than the left ventricle, especially if accompanied by paradoxical septal motion, this is suggestive of massive pulmonary embolus and may alert the clinician to the need for thrombolysis. Long-standing pulmonary hypertension is suggested by a right ventricular free wall of >4 mm. A hyperdynamic well-filled ventricle suggests sepsis. An empty left ventricle (when the ventricular walls meet end systole) suggests profound hypovolaemia. This is further reinforced if the diameter of the inferior vena cava (IVC) is under 12 mm and/or collapses greater than 50% with inspiration in the spontaneously ventilating patient. An IVC of greater than 25 mm especially with no or minimal collapse ( 20 cm H20 (Figure 10.16). In one study, figures suggested 100% sensitivity for 5-mm-diameter optic sheath to detect patients with elevated ICP but further large studies are required to confirm this.

Method

The study is performed using a linear transducer held over the closed upper lid. The lid is protected using a plastic dressing and gel applied. The transducer is adjusted until the optic nerve is visualised and the diameter measured 3 mm posterior to the disc.

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ABC of Prehospital Emergency Medicine

Method

Bone is an excellent reflector of USS energy and thus the cortex appears echogenic. Fractures are readily identifiable and appear as a step or irregularity in the cortical line (Figure 10.17). A linear highfrequency probe is used. Like plain films, images are obtained in two perpendicular plains but can also be moved around the bone to obtain the optimum view.

Vitreous Optic disc

Tips from the field ONSD (within arrows)

1 Dist 3.02 mm 2 Dist 3.78 mm

Figure 10.16  The measurement of optic nerve diameter 3 mm posterior to the optic disc (Dr Vivek Tayal, Annals of Emergency Medicine 2007:49(4): 509–514, with permission from Dr Vivek Tayal, 2007).

E – The role of ultrasound in the evaluation of other injuries Diagnosis of bone injury USS has been shown to be useful in diagnosing fractures with a high sensitivity and specificity. This may be useful in the resourceconstrained environment (e.g. military, mass casualty) when radiographs are unavailable. It has also been used in the identification of dislocations and to guide reduction with similar accuracy to plain films.

Lateral malleolus fracture

Figure 10.17  Ultrasound can clearly show the fracture as a step in the cortex – in this case a fractured fibula (courtesy of Marieta Canagesabey and Prof Simon Carley, Manchester Royal Infirmary, Manchester, UK).

• USS is highly user dependent but safe to learn for patients and practitioners alike – start as soon as you can! • Before picking up the probe, think about how the results of the scan will change your management. If it won’t – do not delay transfer. • USS can identify pneumothoraces more accurately than chest x-ray. • Don’t always assume free fluid on FAST is blood (e.g. ascites, peritoneal dialysis). • USS is useful in the peri-arrest patient in defining the aetiology of hypotension/cardiac arrest not due to rhythm ­disturbance. • If you can’t see anything – use more gel, find a better acoustic window, and check your transducer, depth, and gain.

Further reading Abboud PA, Kendall JL. Ultrasound guidance for vascular access. Emerg Med Clin North Am 2004;22:749–773. APA Price S, Uddin S, Quinn T. Echocardiography in cardiac arrest. Curr Opin Crit Care June 2010;16;3:211–215. doi: 10.1097/ MCC.0b013e3283399d4c. Finn TE, Ward JL, Wu CT, Giles A, Manivel V. COACHRED: a protocol for the safe and timely incorporation of focused echocardiography into the rhythm check during cardiopulmonary resuscitation. Emerg Med Australas 2019;31:1115–1118. doi:10.1111/1742-6723.13374. Kimberly HH, Shah S, Marill K, Noble V. Correlation of optic nerve sheath diameter with direct measurement of intracranial pressure. Acad Emerg Med 2008;15:201–204. Lichtenstein DA, Meziere GA. Relevance of lung ultrasound in the diagnosis of acute respiratory failure: the BLUE protocol. Chest 2008;134:117–125. McNeil CR, McManus J, Mehta S. The accuracy of portable ultrasonography to diagnose fractures in an Austere environment. Prehosp Emerg Care 2009;13:50–52. Perera P, Mailhot T, Riley D, Mandavia D. The RUSH exam: rapid Ultrasound in Shock in the evaluation of the Critically ill. Emerg Med Clin North Am 2010;28:29–56. Porter TR, Shillcutt SK, Adams MS, Desjardins G, Glas KE, Olson JJ, Troughton RW. Guidelines for the USE of Echocardiography as a monitor for therapeutic intervention in adults: a source report from the American Society of Echocardiography. J Am Soc Echocardiogr 2015;28:40–56. Rose JS. Ultrasound in abdominal trauma. Emerg Med Clin North Am 2004;22:581–599. Werner SL, Smith CE, Goldstein JR, et al. Pilot study to evaluate the accuracy of ultrasonography in confirming endotracheal tube placement. Ann Emerg Med 2006;49:75–80.

Prehospital Ultrasound

Glossary Anechoic:  No reflected ultrasound; appears black; suggests fluid. Hypoehoic:  Little ultrasound reflected; appears dark grey. Echogenic/hyperechoic:  Highly reflective of ultrasound; appears white. Acoustic shadow:  The dark shadow under an echogenic structure due to little ultrasound energy reaching it.

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Marker or active end of transducer:  Transducers have a mark to one end that corresponds to a mark on the screen. This is to assist the sonographer in orientation of the probe: convention is for the marked end to be orientated to the patient’s right or cranially; unless performing a cardiac study when it is orientated to the patient’s left.

C H A P T E R 11

Analgesia and Sedation Jonathan Hulme1,3,4, Philip Keane2, and Tony Sim2 1

Sandwell and West Birmingham NHS Trust, City Hospital, Birmingham, UK Wye Valley Hospitals NHS Trust, Hereford County Hospital, Hereford, UK 3 West Midlands Ambulance Service (WMAS) University NHS Foundation Trust, West Midlands, UK 4 Midlands Air Ambulance Charity West Midlands UK 2

OV ER VIEW By the end of this chapter you will understand:

Therefore, effective analgesic and psychological support has impact beyond the prehospital phase of the patient’s journey. See Box 11.2.

• The importance of effective analgesia • The various methods of achieving effective analgesia • The technique and monitoring required for safe sedation • The importance of adequate training and skills prior to commencing sedation

Analgesia

Box 11.2  Objectives of effective analgesia To relieve suffering To improve assessment of a patient who is no longer distressed and agitated To reduce physiological stress and prevent avoidable deterioration To facilitate treatment that would otherwise cause significant distress to the patient

The problem with pain Pain is common in prehospital medicine and is defined in Box 11.1. Box 11.1  Definitions Pain: An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage. Pain is always a personal experience that is influenced to varying degrees by biological, psychological, and social factors. Analgesia: Absence of pain in response to stimulation which would normally be painful. This is usually achieved by administration of drugs or other methods. Procedural Sedation and Analgesia (PSA): Synonymous with the term ‘analgosedation’, PSA involves the use of short-acting analgesic and sedative medications to enable clinicians to perform procedures effectively, while monitoring the patient closely for potential adverse effects. PSA exists along a spectrum ranging from minimal sedation with analgesia to general anaesthesia.

Acute pain has adverse physiological and psychological consequences; both are important to address early and one can affect the severity of the other. Poor analgesia worsens patients’ perception of pain, both around the time of injury and long after the initial insult. The psychological consequences make effective analgesia more difficult to achieve; consider the scared patient who recoils from minor interventions such as cannulation. Inadequate management of acute pain prehospitally has been identified as a major risk factor for developing chronic pain.

ABC of Prehospital Emergency Medicine, Second Edition. Edited by Tim Nutbeam, Matt Boylan, Caroline Leech, and Clare Bosanko. © 2023 John Wiley & Sons Ltd. Published 2023 by John Wiley & Sons Ltd.

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Pain is a trigger of the ‘injury response’, causing activation of complex neurohumoral and immune responses (including hyperglycaemia, fat and protein catabolism, blood vessel permeability), which is necessary for healing and recovery. However, prolonged painful stimuli, without effective analgesia, produces a counterproductive stress response that hinders normal adaptive physiological processes. For example, sympathetic stimulation can potentially lead to myocardial ischaemia. Effective, early pain control encourages healing, reduces the magnitude of the stress response, shortens hospital stay, and reduces morbidity and mortality.

Physiology of pain The body’s ability to detect injury is an important protective mechanism. An individual is alerted to tissue damage by acute pain. Receptors (nociceptors) detect a range of noxious stimuli (heat, cold, pressure, chemical). The initial response is modulated peripherally by altered conditions in damaged areas including increased concentrations of proinflammatory cytokines, substance P, and prostaglandins. Stimuli are transduced to action potentials and transmitted to the central nervous system via fast (myelinated and medium diameter) Aδ-fibres, which transmit sharp and well-localised pain signals. The more numerous slow (unmyelinated and small diameter) C-fibres are responsible for transmitting the duller, more poorly localised pain sensations. In the spinal cord via the spinothalamic tract, there is fast transmission to higher centres on the contralateral side of the injury. From there, axons carry signals to the higher cortical areas where the

Analgesia and Sedation

perception of pain is realised in terms of location, severity, characteristics, and emotional associations. Modulation of the pain response occurs both peripherally and centrally and can act to increase or diminish the perception of pain. For example, modulation can cause previously painless stimuli to become painful (wind-up phenomena). Conversely, it can reduce the number of action potentials reaching the sensory cortex via the endogenous opiate system and help alleviate pain perception. See Figure 11.1.

Principles of management of acute pain Although pain is commonly encountered; adequate treatment is often lacking. Recommendations for prehospital pain management are internationally agreed, by civilian and military representatives, and are appropriate aims for every practitioner (Box 11.3). Box 11.3  Practice recommendations on prehospital pain management from the National Association of EMS Physicians and endorsed by the UK military Mandatory assessment of both presence and severity of pain Use of reliable tools for the assessment of pain Indications and contraindications for prehospital pain therapy Non-pharmacological interventions for pain management Pharmacological interventions for pain management Mandatory patient monitoring and documentation before and after analgesic administration Appropriate handover and transfer of care to hospital Quality improvement and management structure to ensure appropriate use of prehospital analgesia

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Assessment of pain Poor analgesia provision is frequently due to under-appreciation of a patient’s needs. Although a difficult concept to practice at all times, pain is whatever the experiencing person says it is, existing whenever they say it does. An inability to verbalise or describe discomfort, for example in children or those with cognitive impairment, should not prevent provision of good and timely analgesia. Appropriate assessment is the key. There are reliable tools for scoring pain that are rapid and objective both before and after analgesia. For adults the Numeric Rating Scale (0–10) is well validated. For infants there are scales based on body movements and consolability and for children many practitioners employ a facial expression tool to gauge levels of pain. For all patients, the trend in pain scores is more important than a one-off or absolute value, and frequent reassessment of pain is crucial. After appropriate adequate analgesia, the patient should report an improvement in their pain score.

Treatment of pain There are no contraindications for prehospital analgesia although some methods may be (relatively) contraindicated in some patients, e.g. opioids in brain injury may be problematic if they lead to hypercapnia. Good analgesia may assist in the monitoring and treatment of the patient. For example, tachycardia caused by pain may make the diagnosis of shock more difficult and ventilatory effort in those with rib fractures will be improved with effective analgesia. Patients typically need a combination of non-pharmacological and pharmacological methods for effective analgesia.

Figure 11.1  Transduction, transmission, perception, and modulation of a painful stimulus.

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Non-pharmacological interventions Reassurance through effective therapeutic communication significantly alleviates distress; a professional, empathic approach distracts from the painful stimulus. For children, parental presence reduces distress for both child and parent. Distraction techniques are particularly effective, especially in children, and should be adapted according to the child’s developmental level. Distraction can be considered either passive or active. Passive distraction involves the child remaining quiet while the healthcare professional provides the distraction by, for example, singing, talking, or reading a book. Active distraction encourages the child to participate in an activity, for example playing a video game whilst the painful procedure is performed. Such reassurance and distraction techniques are highly effective at permitting intravenous cannulation to enable pharmacological analgesia if required. Experienced parents and healthcare professionals are invaluable sources of learning and close attention should be paid to the techniques they employ. Immobilising fractures or dislocations reduces pain and bleeding. Traction splints are particularly good for femoral fractures, as a significant amount of pain is due to unopposed contraction of the thigh muscles. Cold water reduces the pain of superficial burns immediately after injury. Dressings prevent airflow across the burn (e.g. cellophane wrap) and provide additional analgesia.

Pharmacological interventions Drugs affect the pain pathway at specific points. Multimodal analgesia describes the actions of multiple types of drugs working synergistically to produce analgesia superior to one drug acting alone in higher doses. Multimodal analgesia is considered to be good practice if it reduces the dose required of an agent that has the potential to cause harm. For example, co-administration of paracetamol (acetaminophen), codeine, and non-steroidal anti-inflammatory drugs can reduce the amount of morphine required over several hours. Within the timeframe of the prehospital practitioner these benefits are unlikely to be seen and, although they are likely to influence a patient’s ongoing journey, many prefer a simpler regimen of drugs they know and are familiar with. There are a variety of routes of administration (Table 11.1). It is worth noting most drugs administered IV may also be administered IO. Some specific drugs are considered further:

There are no significant side effects except sedation and nausea, but it is contraindicated in patients with air-containing closed spaces since N2O diffuses into them with a resulting increase in pressure. This is dangerous in pneumothorax, bowel obstruction, intracranial air after head injury, and decompression sickness. Entonox® separates into its component gases at approximately −6°C, risking delivery of a hypoxic mixture. Cylinders should be stored horizontally and at low temperatures repeated inversion of the cylinder prior to use is recommended to mix the gases. The main limitations in the prehospital setting are not pharmacological. The cylinder and delivery system are heavy and can mean that a very useful analgesic is left in the emergency vehicle if other equipment needs to be carried to the patient. Prehospital services are being asked to review their use of Entonox® and to consider alternatives as there are significant environmental consequences: nitrous oxide is both ozone depleting and has global warming potential. It is estimated that 30 minutes of Entonox® use produces the equivalent emissions of approximately 38 kg of CO2: the same as driving a medium-sized petrol car over 120 miles.

Methoxyflurane: Penthrox®

Methoxyflurane is a halogenated ether, self-delivered to the patient via an inhaler (Figure 11.2). It was originally used as an anaesthetic agent, but is now licensed for procedural sedation and analgesia (PSA) in the UK for adults. It provides rapid, effective analgesia and reduces the need for opiates in the prehospital setting. The main side-effects are nausea and headaches. Its use has been relatively limited due to concerns of causing nephrotoxicity and hepatitis in certain patient groups, but there is no strong evidence to support this when Penthrox® is used sparingly, at sub-anaesthetic levels, for acute pain relief before longer lasting analgesia can be established.

Opioids

Opioids are widely used. Morphine and fentanyl are common and equally effective. Fentanyl is faster acting but shorter lasting. It is more lipid soluble than morphine so can be delivered via alternative routes (nasal and buccal) while longer lasting analgesia is arranged.

Paracetamol (acetaminophen) and non-steroidal anti-inflammatory drugs

These good analgesics are frequently used in the prehospital phase. Use includes self-administration in patients seen and discharged from scene and oral administration to patients with less severe pain. Intravenous paracetamol has an opioid-sparing effect and is widely used as part of the regimen for moderate–severe pain.

Entonox®: Nitrous oxide: oxygen (50/50 mix)

Rapid onset and offset of analgesia. It is used while other means of longer lasting analgesia are established or as brief additional analgesia during painful episodes, e.g. movement of an injured limb into a splint.

Figure 11.2  Penthrox inhaler device with surmounted activated carbon chamber. Published with permission from Galen Limited.

Analgesia and Sedation

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Table 11.1  Pharmacological interventions: routes of administration Route

Example

Benefits

Limitations

Oral

Paracetamol, NSAIDS, opioids

Cost and ease Widely acceptable

Conscious and able to swallow (nausea) Slow onset Poor titration Poor for severe pain Variable absorption (gastric stasis/first pass)

Inhalational

Entonox, methoxyflurane ‘Penthrox’

Rapid Self-administration (titrated by patient) Short lasting Adjunct to other agents

Inability to understand/coordinate needs Short lived Nausea and vomiting Cumbersome equipment Cough, mucosal irritation

Intravenous

NSAIDS, Opioids, ketamine, paracetamol

Rapid No first pass Titratable

IV access – difficult in some and needs training

Nasal

Opioids (fentanyl), ketamine

Rapid Easy No needles Titratable

Absorption may be affected by mucosal conditions, blood, etc. Legislation

Topical

Local anaesthetic (LA) cream Slow release opioids

Painless

Poor titration Limited range of drugs for most patients Slow onset Beware toxicity (LA overdose, concealed opioid patches)

Intramuscular

Opioids

No IV access needed

Slow and variable onset Potential for delayed overdose Damage to nerve Inadvertent IV/IA injection

Buccal

Opioids

Rapid Painless Avoids first pass Spit/swallow when finished

Limited range of drugs Requires intact swallow and co-operation

Rectal

Paracetamol, NSAIDS

Rapid Avoids first pass Easily self-administered

Acceptance

Intraosseous

NSAIDS, Opioids, ketamine, paracetamol

Rapid No first pass Titratable More rapid than IV, requires less skill

Small risk of bone infection Training/legislation to be able to do it

Perineural (regional anaesthesia)

Local anaesthetics – lidocaine, bupivacaine

Rapid Neurovascular damage Effective Accidental IV administration No systemic metabolism and effects LA toxicity Requires specific training

Titration of opioids to best effect is essential, but morphine takes 20 minutes to reach maximal effect with significant interpatient differences in dose requirements. This can be impractical when aiming to provide good pain relief during dynamic situations such as patient transport, e.g. analgesia for a fractured neck of femur when moving downstairs or extricating an injured patient from a vehicle. Respiratory depression is uncommon with careful titration. The incidence of nausea is small but may be treated with a co-administered anti-emetic.

Ketamine

Ketamine is a dissociative anaesthetic chemically related to phencyclidine (PCP/‘angel dust’). It is commonly used for anaesthesia,

sedation, and acute pain, as well as for its local anaesthetic properties and role in treating neuropathic pain. At subanaesthetic doses (i.e. 0.25–0.5 mg/kg IV/IO) it provides excellent short-lasting analgesia, sedation, and amnesia: ideal for procedural sedation and analgesia. It has a rapid onset (about 1 minute) and is easily and rapidly titrated to effect. This lasts approximately 10–15 minutes: repeated small doses are often needed, for example during extrication of the trapped patient. Though most often administered intravenously, it is effective via numerous routes (oral, rectal, nasal, intraosseous, and intramuscular for moderate and severe pain). Ketamine has a wide therapeutic index: the difference between the effective dose and amount needed in overdose to cause significant harm is large.

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Ketamine has widespread actions beyond its analgesic and anaesthetic effect. Airway patency and reflexes are usually preserved, with obvious advantages in the sedated patient. However, patients sedated with ketamine will be less tolerant of supraglottic airway devices than with other agents e.g. propofol. It suppresses breathing less than other potent analgesics, and apnoea is unusual unless an intravenous or intraosseous dose is administered too rapidly. Hypersalivation may occur but is rarely a practical problem; coadministration of an antimuscarinic is seldom required. Hypertension and tachycardia may occur, which has implications in the prehospital setting. The increased cardiovascular workload is undesirable in patients with severe ischaemic heart disease. Increased blood pressure may necessitate increasing tourniquet or direct pressure to maintain haemorrhage control. Crucially, do not assume that tachycardia in patients receiving ketamine is a drug effect: it may be due to shock. In a shocked patient, who has already exhausted their catecholamine response, ketamine will still precipitate a hypotensive episode and the dose should be reduced accordingly in this patient group. Ketamine may increase cerebral perfusion pressure, an effect previously thought to contraindicate its use in head injuries, but it is now considered safe. Increased muscular tone after ketamine can make extrication more problematic as the limbs become more difficult to bend. Reducing dislocations may be more difficult. The main adverse effect of ketamine is psychological disturbance; up to 20% of patients experience emergence phenomenon (disorientation ± agitation ± psychological distress) as the drug wears off. Short-term hallucinations are frequent; long-term nightmares and hallucinations are reported but rare. The incidence and severity of these effects is reduced in the young and elderly and can be reduced by careful co-administration of benzodiazepines or opioids. Control of the environment is useful in managing ­emergence phenomena; this may be difficult in the prehospital environment.

Local anaesthesia

Local anaesthetics are drugs that temporarily block neuronal transmission, thus preventing pain signals reaching the brain to be perceived. Their uses include: Topical application: To assist venepuncture in non-time critical situations, for children and needle phobic adults, though this takes up to 45 minutes to be effective. Subcutaneous injection: Small volumes injected around wound site to enable cleaning, exploration, and closure. Peripheral nerve blocks: An attractive option that can provide excellent long-lasting analgesia without the side effects of systemic analgesia, e.g. sedation, confusion, respiratory depression. Blocks particularly suited to the prehospital setting are those that can be performed by landmark technique without ultrasound guidance and that require minimal patient repositioning. Though not widespread, blocks increasingly used are the fascia iliaca block for femoral fractures, serratus anterior plane (SAP) for rib fractures, and digital ring block for finger injuries. Table 11.2 summarises the more commonly employed prehospital peripheral nerve blocks.

Drawbacks of prehospital regional anaesthesia include time required for the procedure (preparation and performance), need to alter or optimise patient positioning, difficulty creating a relatively sterile field, and the need for additional specific training for prehospital practitioners. Despite traditional concerns, there is no convincing evidence that nerve blocks used in trauma patients delay diagnosis of compartment syndromes. Current evidence is limited and such blocks may often prove impractical to perform prehospitally, but they remain a valuable option in specific situations for a subset of providers. Advantages of these techniques may include an improved quality of analgesia in the Emergency Department and better patient satisfaction within appropriately selected groups.

Procedural sedation and analgesia (PSA) What is it? Some interventions are distressing for patients because they increase pain (e.g. extricating the injured, trapped patient) or are invasive (e.g. insertion of an intercostal drain). Procedural sedation and analgesia (PSA) aims to relieve anxiety, reduce pain, and provide a degree of amnesia by administration of short-acting sedatives and analgesics. Previously called ‘conscious sedation’, the name has changed as effective sedation often alters consciousness.

How much is the patient sedated? Sedation is a continuum, although discrete definitions are proposed (Table 11.3). Prehospital PSA should aim to be ‘moderate’ where verbal contact with the patient is maintained, and avoiding potential complications with airway, breathing, and circulation. Ketamine transcends these definitions, being capable of marked changes in responsiveness to a trance-like state while (usually) maintaining airway reflexes, spontaneous respiration and cardiovascular status.

What is required for procedural sedation? Monitoring In accordance with minimum standards used during anaesthesia: ● ● ●

●

ECG (three lead) pulse oximetry automated non-invasive blood pressure (auto cycle every few minutes) visual monitoring (respiratory rate, alertness, response to painful stimuli, etc.)

End-tidal capnography is helpful as, even though numerical value will not be accurate, the presence of a trace is reassuring and allows assessment of respiratory rate. An elevated ETCO2 (>45 mmHg) suggests hypoventilation earlier than a fall in pulse oximetry, especially if supplementary oxygen is used. Continuous assessment by an experienced clinician is a key component of safe monitoring of PSA.

Digital nerves Hand placed face down on surface. LA injected into digital webspace either side of affected finger

Intercostobrachial, lateral cutaneous branches of the intercostal nerves, long thoracic and thoracodorsal Requires ultrasound. Probe position: coronal plane over the 4th or 5th rib in mid axillary line until both the latissimus dorsi and SA muscles can be delineated and the SA plane identified

Injection site 1 cm caudal at the junction of the lateral and middle thirds of a straight line between the anterior superior iliac spine (ASIS) and pubic tubercle. N.B. Can be safely performed using landmark technique only

 

 

1–2 ml of 1–2% lidocaine or levobupivacaine

Not applicable

Reading’ section for full reference.

Source: FIB and digital ring block surface anatomy image created by authors. FIB sonoanatomy image published with permission from authors; SA block surface and sonoanatomy images published with permission from authors. See ‘Further

20–30 ml of 0.25% levobupivacaine

La = local anaesthesic inflitration in SA plane, sa = SA muscle, r = ribs, pl = pleura

 

Typical LA used, 30–40 ml of 0.25% levobupivacaine strengths and volumes

Note: white needle indicates needle insertion direction

 

Sonoanatomy

Surface anatomy

Anatomical landmark description

Nerves affected Femoral and lateral femoral cutaneous

Finger dislocations, fractures, and lacerations

Rib fractures

Neck of femur or femoral shaft fractures

Prehospital analgesic indications

Digital ring

Serratus Anterior (SA) plane

Fascia iliaca plane

Type of block

Table 11.2  Local Anaesthetic Nerve Blocks

 

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Table 11.3  Sedation Minimal sedation/ anxiolysis

Procedural sedation Moderate sedation

Deep sedation

General anaesthesia

Responsiveness

Normal response to verbal stimulation

Purposeful response to verbal or tactile stimulation

Purposeful response following repeated or painful stimulation

Unarousable even with painful stimulus

Airway

Unaffected

No intervention required

Intervention may be required

Intervention often required

Spontaneous ventilation

Unaffected

Adequate

May be inadequate

Frequently inadequate

Cardiovascular function

Unaffected

Usually maintained

Usually maintained

May be impaired

(Continuum of depth of sedation: Definition of general anaesthesia and levels of sedation/analgesia Committee of Origin: Quality Management and Departmental Administration (2009) / Reproduced with permission from American Society of Anesthesiologists. Note: In practice there is minimal distinction between deep sedation and general anaesthesia.

Preparation Preassessment of patients should include airway assessment, ability to withstand haemodynamic effects of drugs used in PSA, and presedation conscious level. Most patients undergoing prehospital PSA will be unfasted and are more likely to aspirate stomach contents if protective airway reflexes are lost. Equipment that would be required for emergency anaesthesia or cardiovascular collapse must be available. Simple airway adjuncts such as oropharyngeal or nasopharyngeal airways should be readily accessible. These are described in Chapter 6. Modifying the environment, aiming for calm with minimal stimulation, may facilitate sedation and help to ameliorate unpleasant psychological effects from ketamine.

Drugs Numerous agents are available but whatever drugs are used, guidelines emphasise the need for titration to effect, giving each dose time for full effect before adding more. Polypharmacy should be avoided. Successful PSA can be readily achieved for most patients with the use of one or two drugs; titration to effect is easier the fewer drugs are used. In difficult situations what is usually needed is more patience to correctly titrate the therapeutic agent, additional non-pharmacological methods (i.e. splinting), and better teamwork, not an extra drug. A popular prehospital combination is ketamine and midazolam. Ketamine provides excellent analgesia with a sedative dissociative state, while the midazolam limits ketamine’s psychological side effects. Supplemental oxygen is typically administered.

Any practitioner aiming to administer moderate sedation should be able to rescue patients who enter deep sedation or general anaesthesia. In the prehospital arena, where experienced support may not be immediately available, PSA should only be undertaken by practitioners proficient in advanced airway management and life support. Regular experience providing PSA is important for maintaining such skills.

Handover to hospital A full verbal and written account of analgesic and sedative drugs must be provided to hospital clinicians taking over care of patients after PSA. This is essential for hospital clinicians to distinguish between organic illness and effects of analgosedative agents, as well as informing decisions on subsequent management, e.g. RSI within ED. Tips from the field • Ask the patient how bad their pain is. Treat it and then ask them again to see if you have made it better. If not, they need more analgesia! • A distressed patient in pain is upsetting for everyone. Effective pain relief is good for the patient, satisfying for you and calms the whole emergency team making the rest of the rescue less stressful. • Non-pharmacological methods of pain relief are very effective and can avoid or reduce drug requirements. • Deep sedation is, in practice, general anaesthesia. If you wouldn’t give your patient a general anaesthetic, don’t be tempted to deepen ‘sedation’ to similar levels. • Avoid polypharmacy. Have a small selection of drugs you use regularly and get very used to what they do.

Training

Further reading

Procedural sedation can inadvertently progress to general anaesthesia with the associated hazardous physiological changes such as loss of airway and haemodynamic instability. Illness, acute or preexisting, and injury increase the likelihood of adverse events even with small amounts of sedation.

AAGBI. Safer Prehospital Anaesthesia, 2017. London: The Association of Anaesthetists of Great Britain and Ireland. ASA Standards, Guidelines and Statements. Continuum of depth of sedation: Definition of general anaesthesia and levels of sedation/ analgesia. 2019.

Analgesia and Sedation

Blayney MR. Procedural sedation for adult patients: an overview. BJA Education 2012;12;4:176–180. Elwen F, Desai N, Parras T, Blanco R, Duran J. Seratus Plane Block. World Federation of Societies of Anaesthesiologists – Tutorial of the week 427. June 2020. https://resources.wfsahq.org/atotw/9317. Fleming I, Egeler C. Regional anaesthesia for trauma: an update. BJA Education 2014;14;3:136–141.

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Range C, Egele C. Fascia iliaca compartment block: landmark and ultrasound approach. World Federation of Societies of Anaesthesiologists – Tutorial of the week 193. Aug 2010. https:// resources.wfsahq.org/atotw/fascia-iliaca-compartment-block-landmark-andultrasound-approach.

CH A P T E R 12

Transfer and Retrieval Richard Browne1,2 and Scott Grier3,4 Based on a chapter by: Peter Aitken5, Mark Elcock5,6, Neil Ballard5, and Matt Hooper5 1

Queen Elizabeth Hospital, Birmingham, United Kingdom ACCOTS Adult Critical Care Transfer Service, Birmingham, United Kingdom 3 Southmead Hospital,Bristol, United Kingdom 4 Retrieve Adult Critical Care Transfer Service, United Kingdom 5 James Cook University, Townsville, QLD, Australia 6 Retrieval Services Queensland, Brisbane, QLD, Australia 2

OV ER VIEW By the end of this chapter you should know: • The importance and purpose of transfer and retrieval • The different types of transfer • The advantages and disadvantages of different modes of transport • The steps required to prepare a patient and team for transfer • The factors affecting the ability to provide care during transfer

Introduction Critically ill and injured patients frequently require transfer as part of their pathway of care, which can be from the scene of an incident to hospital or between hospitals. Patients should receive high-quality care throughout. Dedicated and highly trained transfer and retrieval teams can optimise patient outcomes, delivering critical care resusciation and stabilisation during transfer. This requires the deployment of appropriately trained team members with suitable equipment and effective communication and liaison between referring, transferring, and receiving organisations. The risk of transfer should be carefully balanced with the perceived benefits of moving the patient to the receiving centre.

Definitions and terminology Patient transfer can be defined as the use of clinicians (medical, nursing, paramedic, other) to facilitate clinical care and safe transfer of a patient from one location to another. Primary transfers are from the prehospital site or scene of an incident to a healthcare facility.

ABC of Prehospital Emergency Medicine, Second Edition. Edited by Tim Nutbeam, Matt Boylan, Caroline Leech, and Clare Bosanko. © 2023 John Wiley & Sons Ltd. Published 2023 by John Wiley & Sons Ltd.

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Secondary transfers are from one healthcare facility to another and are also referred to as interhospital or interfacility transfers. Primary transfers are sometimes sub-categorised by the transport medium and/or the time of their attendance. The term ‘delayed primary’ has emerged, describing the emergent transfer of a patient from a referring healthcare facility that has limited facilities and/or clinical expertise. Patients requiring secondary transfer can be sub-categorised by the reason for transfer: ●

●

●

Escalation of care: transfer to facilitate access to specialist care not available in the referring hospital Repatriation: transfer closer to home after completion of specialist care or when illness or injury has occurred in a distant location Capacity (historically termed ‘non-clinical’): transfer of patients to enable the provision of emergency medical or surgical care when there is insufficient space, staff, or equipment. This has been particularly relevant around the world during the COVID-19 pandemic.

The characteristics of primary and secondary transfers are described in Table 12.1. Dedicated transfer and retrieval services are extremely varied across the globe. Some purely deliver prehospital emergency medical care; others are focused upon one age group (e.g. neonatal transfer), whilst others cover multiple ages and pathologies. Geographical operating areas and transfer distances also vary enormously from urban/sub-urban systems with short road transfer times to decentralised rural populations with long fixed-wing transfer times (Figure 12.1). Case mix and geography determine the structure of each service including selection of appropriate crew, equipment, and transport platform.

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Table 12.1  Characteristics of primary and secondary retrievals Primary

Secondary

Pre-deployment clinical information

Limited

Detailed

May be from member of public

Received from referring clinician

Response coordination

Rapid

Graded response

Scene response reliant on integrated emergency medical system, e.g. 999/112/000

Generally more complex and time consuming Multiple clinician involvement and critical care bed finding

Immediate response

Graded, triaged response

Patient priority

Dependent on patient condition and capability of referring facility Patient severity

Variable but often critical

Platform team members

Paramedic/nurse ± physician

Practitioner/advanced practitioner ± physician

Platform

Dependent on scene characteristics and distance

Dependent on distance and platform availability

Scene/facility

Fluid and unpredictable

Controlled

Multiagency management

Multidisciplinary management

Presence of media and bystanders

Interface with unfamiliar clinical staff

Lighting

Variable

Controlled

Temperature

Variable, potential for extremes

Controlled

Humidity

Variable

Controlled

Power

Dependent on scene response, finite

Mains source and back up battery

Suction/oxygen

Portable and finite

Fixed and reliable

Personal protective equipment

Highly specific for scene response

In general normal standard precautions

Clinical equipment

Familiar

Unfamiliar if using referring facility’s equipment

Limited to that carried in standardised equipment bags

Access to enhanced capabilities and resources, e.g. pathology, radiology

Clinical support

Limited to responding clinical crew mix

Enhanced access dependent on capability of referring facility

Clinical interventions

Life/limb/sight saving

Up to and including advanced critical care procedures and interventions

On scene time

Rapid turnaround

Time criticality varies depending on patient

Minimal patient packaging

Enhanced packaging

Variable Ability to tailor clinical crewing

must be adequately trained and equipped to deliver high-quality care, to maintain their own and their patient’s safety and to work effectively in the environment and across the geography of their system’s operations.

Modes of transport

Figure 12.1  Transport from isolated rural centres.

Patient transfer and retrieval may occur using any mode of transport available but usually involves road or air (rotary and fixed wing). See Figures 12.2, 12.3, 12.4. Each has inherent advantages and disadvantages that must be appreciated and understood by the transfer and retrieval services themselves, those tasking the assets, referring and receiving centres. These issues are summarised in Table 12.2 and can be classified as system (cost, availability), logistics (site access, space, range), and patient care (patient access, effects of transport).

Team members

Tasking and coordination

Physicians, practitioners, paramedics, nurses, and other personnel are all used as transfer and retrieval team members. Variances between systems are partly determined by case mix, partly by national standards and partly by history. Regardless of discipline, all team members

The tasking and deployment of transfer and retrieval services requires careful consideration of the available resources, geography, weather, referring and receiving facilities, and clinical needs of the patient.

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Coordination ensures the most appropriate response (team, timeframe, transport modality) for a specific clinical situation. Undertriage can result in patient delays and potential for adverse patient outcomes. Over-triage can increase resource utilisation, add risk to teams and patients, and mean that services are not available when other patients require them. When coordinating a response, there is a continuous evaluation of the risks and benefits, balancing potential patient benefits with team and patient safety. Many services utilise decision-making algorithms to consider issues such as: ●

●

Figure 12.2  Road ambulance.

● ●

Logistics (distance to travel, range of transport modality, availability, access) Patient requirements (time criticality, diagnosis, specific needs during transfer) Team skill mix (meeting needs of the patient) Team safety (hours worked, weather, time of day)

Computer-assisted and clinician-supported tasking systems both have merit. The balance between safety and patient outcome are the primary considerations and are not mutually exclusive. Services should ensure efforts are made to reconcile all the above factors when making a deployment decision and may utilise a coordination risk matrix (such as the example in Table 12.3) to facilitate this.

Effects of transfer

Figure 12.3  Rotary transfer.

Patient transfer is not without risk, and the environment has its own unique characteristics that influence patient care and the ability of the team members to provide it. These are outlined in Table 12.4 and, whilst some are common to all modalities, others are more pronounced in one. Noise and vibration affect crew well-being, and fatigue management is important. This requires system structures and processes designed to minimise and mitigate fatigue as well as team awareness and forward planning to maximise safety and effectiveness, even when it is dark and cold and the team are hungry and tired. There are specific factors that are unique to transfer by air, outlined in Table 12.5. In summary, as altitude increases, temperature falls, there is less oxygen and gas volumes expand. All can influence patient care.

Preparation for transfer and care en route

Figure 12.4  Fixed wing (Royal Flying Doctor Service) in Australian outback.

Dedicated services often provide clinical coordination, triage, and decision-support, in addition to a physical transfer platform and team. This facilitates and guides initial patient resuscitation and stabilisation prior to the arrival of a dedicated team, as well as supporting the timely and efficient transfer of patients to the most appropriate facility.

The transfer environment, regardless of transport modality, compromises the transfer team’s ability to deliver patient care as there is limited space, access to, and visibility of the patient, limited equipment and resources, and limited ability to move due to safety restraints. To mitigate these factors, transfer and retrieval services have organisational systems and processes to address transfer trolley/ stretcher configuration, cabin configuration to ensure access to vital equipment, seating, and harness layout to maximise visibility and patient access. Figures 12.5, 12.6, and 12.7 give examples of transport modality configurations. Key to safe and high-quality patient care en route is the assessment, resuscitation, stabilisation, and packaging of the patient prior to departure. Many transfer and retrieval services utilise

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Table 12.2  Comparison of transport platforms Road

Rotary

Fixed wing

Distance

 250 miles

Consider > 250 miles

Access

Minimises delays in moving between modes of transport Reduces risks of multiple patient handovers

Allows ‘point to point’ transfer depending on landing site availability

Needs secondary road transfer May incur multiple patient handovers

Special access

Limited to road

May be the only option for some geographic or rescue situations

Needs landing strip or airport

Equipment

Well-equipped if dedicated platform with stretcher/transfer trolley, oxygen, medical devices

Well-equipped if dedicated platform with stretcher/transfer trolley, oxygen, medical devices

Well-equipped if dedicated platform with stretcher/transfer trolley, oxygen, medical devices

Capacity

Usually one patient

One or two patients depending on aircraft type

One or two patients but larger aircraft are available

Response times

Usually rapid

Can be rapid depending on system

Often slower

Able to stop or divert if patient deteriorates

Limited diversion ability

Very limited diversion ability

Limitations

Road conditions and traffic

Weather

Weather (less than rotary)

Less limited by weather

Landing site availability

Landing strip/airport availability

Transport effects

Motion effects (including acceleration and deceleration)

Motion effects, noise/vibration effects

Effects of altitude – reduced by ability to pressurise cabin

Altitude

Ground level

0–10,000 feet (non-pressurised)

0–35,000 feet (pressurised)

Cost

Low cost

High cost

High cost

Availability

Widespread

Less common

Less common

Table 12.3  An example of a risk matrix for tasking and coordination from Retrieval Services Queensland, Australia, that combines patient priority and aviation risk to recognise both safety and patient outcome Patient priority score → Aviation risk score ↓

1

2

3

4

5

Critical safety decision (10+)

Mandatory consultation between Senior Medical Coordinator and Senior Pilot

X

X

X

X

Extreme caution (8–9)

√

Consultation within aeromedical crew required

Consultation within aeromedical crew required

X

X

Caution (5–7)

√

√

√

Consultation within aeromedical crew required

X

Normal operations (0–4)

√

√

√

√

√

Table 12.4  Effects of transfer and clinical implications Effects

Clinical implications

Vestibular dysfunction/spatial disorientation

Fatigue, nausea

Temperature – cold

Coagulopathy, shivering, fatigue

Temperature – heat

Fatigue, nausea

Linear acceleration/deceleration

Haemodynamic instability (especially if patient is hypovolaemic) Positioning of patient

Noise

Difficulties in communication, alarm systems need to be visual and auditory, fatigue

Vibration

Interference with monitoring (non-invasive blood pressure, ECG), clot disruption, fatigue

Turbulence

Nausea, fatigue, safety

Space

Limited access to patient and equipment

Limited ambient lighting

Limited ability to visualise patient, equipment, and documentation

Psychological effects of transfer

Anxiety, distress, safety. May be exacerbated by flight

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Table 12.5  Flight physiology Physiology

Clinical implications

Hypoxia with increasing altitude

Borderline gas exchange may be compromised (acute illness/injury or chronic lung conditions) Consider the use of supplemental oxygen on patients being transported

Total barometric pressure = sum of partial pressures (Dalton’s Law) Whilst percentage of oxygen remains constant, partial pressure reduces with altitude

Gas-filled cavities (middle ear, sinuses, lungs especially pneumothorax, bowel obstruction, pneumocranium, and eye with penetrating injuries) can expand Consider decompression prior to flight

Gas volume increases with altitude as pressure decreases P1V1 = P2V2(Boyle’s Law)

Equipment (cuffed endotracheal and tracheostomy tube, vacuum mattress, gravity-controlled intravenous giving sets, Sengstaken tube) Consider decompression and/or careful in-flight monitoring

Figure 12.5  Space and configuration inside a road vehicle.

Figure 12.7  Space and configuration inside a fixed wing aircraft.

Table 12.7 is an example of a patient preparation checklist for use by both referring facilities and transfer teams.

Equipment The choice of equipment requires the consideration of several factors, all of which influence the optimum combination of devices: ●

●

●

●

Figure 12.6  Space and configuration inside a rotary wing aircraft.

standard operating procedures (SOPs) to structure these elements and ensure that planning for potential emergencies occurs. Table 12.6 summarises the factors which should be considered during the initial triage and subsequent assessment and stabilisation phases.

Patient factors, including age/size (e.g. neonatal, paediatric, adult), pathologies, likely support requirements Transport medium including size, weight, and specific requirements for aviation Available options and inter-operability between transfer and retrieval services, referring and receiving centres Transfer-specific considerations including screen visibility, auditory alarms, weight, physical size, and robustness (Table 12.8)

Bags containing consumables and drugs vary enormously from service to service. These should be designed with the care needs of the service’s patients in mind. They should be organised and compartmentalised in a way that aids the transfer team in a high pressure emergency situation. This often means dedicated sections for airway, intravenous access, drugs, etc. It is not possible to carry

Transfer and Retrieval

Table 12.6  Preparation of a patient for transport Decision phase

Considerations

Referral

What clinical care does the patient require? Where do they need to be to receive this? How urgently do they require this care?

Resuscitation and stabilisation prior to arrival of the transfer and retrieval team

What can be done to improve the patient’s condition?

Preparation for transfer

What may change or occur en route? How can I prepare for potential emergencies? What effects will transfer have on the patient? Can I do anything to mitigate these? Is there anything I will not be able to do en route? What specific packaging requirements does the patient have? What specialist equipment and/or drugs do I need to prepare prior to departure? How much oxygen do I require? (See Table 12.9.) Have next of kin been informed of transfer? Do they know the destination and are they able to travel to this location?

Care en route

Monitor gas-filled cavities and equipment Monitor effects of transfer on patient physiology and their injury/illness Complete documentation Ensure you communicate with the receiving facility and provide an estimated time of arrival

Table 12.7  Example of a patient preparation checklist for referring facilities and transfer teams Airway

Does the patient require intubating prior to transfer? Endotracheal tube adequately secured Tracheostomy adequately secured, emergency equipment available?

Breathing

Lung protective ventilation? CXR required? Does pneumothorax or chest drain require attention?

Circulation

IV access x2, adequately secured Arterial line if indicated (all intubated patients and all with a vasopressor requirement)

Neuro and sedation

Record pre-intubation GCS Remember regular pupil assessment Is sedation and analgesia adequate? Does the patient require paralysis?

Gastrointestinal

Is a nasogastric tube required? If in situ, does it need aspirating? Stop NG feed (and insulin, if applicable) Consider administration of anti-emetic

Renal

Insert urinary catheter (all intubated patients)

Microbiology

Are there any infection control issues? Does the patient have a high-risk disease that requires specific PPE or infection control measures? Is the patient up-to-date with antibiotics administration?

Blood products

Blood products ordered if required for transfer?

Drugs

Patient allergy status confirmed? Administer medication that is due Does the patient have any issued medications that need to be transferred with them? Prepare adequate infusions for the journey and any spares required At a minimum for a ventilated patient, prepare 3 × the journey’s duration of: ●

Sedative

Opiate of choice Paralysis infusion or 3 × doses ● Noradrenaline (if central access available – metaraminol if not) If uncertain, discuss with transfer team ● ●

Temperature

Maintain patient temperature – do they require active warming? Pay attention to prevent cooling (Continued)

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Table 12.7  (Continued) Packaging

Does the patient require any specific pressure area care? Are monitoring cables tied together? Are infusion lines forming an ‘umbilicus’ and unobstructed? Ensure no items pressing into or sitting on top of patient Is the patient secured to the transfer trolley?

Identification

2 patient identification bands

Documentation

Discharge summary (or transfer letter)? Copy of relevant patient notes including drug chart, blood results, microbiology reports? Has imaging been transferred to receiving hospital?

Next of kin

Aware of transfer and destination?

Table 12.8  Key considerations in equipment selection Transport issues

General Issues

Use (essential or non-essential) Does it offer flexibility or redundancy Ease of use Physical size, storage location Weight Battery life and alternative power source requirements Robustness (consider drop test) Vibration effects Noise (including audible alarms) Options for mounting or securing device

Cost Training required Compatibility with other equipment Reliability Warranty Service requirements (frequency, cost, location) Consumable cost and availability

everything that a hospital would stock, but some redundancy should be included. Consider options for dual use, the necessity for duplication (in event of failure or multiple requirements) and the likelihood of it being required. Fragile items that are mission-critical (e.g. key drugs) must be stored in a suitable bag and in a way that minimises the risk of damage. A key consideration in all equipment and bag use is the systems and processes that enable each item to be ‘mission ready’ when required. Many transfer and retrieval services have strict governance processes around this so that there is adequate training, familiarisation and maintenance. Most require daily checking of key pieces of equipment, and may use a tagging system for bags; single-use plastic tags seal each pouch and pocket once it has been checked by two team members, giving the next user a guarantee that the items they expect to be there are present, and in date. Bag contents should be regularly reviewed and items added or removed only after careful consideration – most services do not allow team members to simply add contents without formal approval. Equipment security, whilst maintaining accessibility and visibility, requires careful consideration. There are a number of solutions to this depending upon the mode of transport: ●

●

●

Dedicated transfer trolleys (Figure 12.8) which have mounts for ventilators, monitors, infusion and volumetric pumps, and a unified power supply. Stretcher ‘bridges’ that secure equipment and are placed over the patient. Cabin mounts for ventilators and monitors that are crash-tested and rated for the particular items.

Figure 12.8  Dedicated critical care transfer trolley with mounts for all equipment.

Many solutions combine the above factors and generally require endorsement by national regulatory bodies to confirm they can withstand the potential forces involved in transfer: acceleration, deceleration, and rotational. Every item of equipment must be secured when a vehicle is in motion – items that are not can become missiles when the vehicle suddenly slows, banks, comes to a sudden halt, or crashes. This rule extends even to small items as a 1 kg ‘lightweight’ bag travelling at 50 mph in the rear of an ambulance will still cause significant harm to an individual. Patients and team members should be adequately secured throughout the journey for the same reasons.

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Oxygen There must be sufficient oxygen to complete a transfer or retrieval. The ability to replace cylinders at the end of a transfer or during a long duration transfer should be planned. Oxygen cylinders must be adequately secured, in line with all other equipment. There is a potential risk of fire and dedicated mounts are required. Team members must be familiar with mounting and storage systems, cylinder connection and disconnection, and cylinder capacity and checking processes for each shift and each transfer. Calculating how much oxygen is required for a particular transfer is a key skill and many services have a standardised approach to this by mandating the calculation and building in additional safety measures or assumptions. Table 12.9 illustrates a simple approach to oxygen usage for a transfer.

Specialised additions A number of specialised additions (equipment or people), may need to be considered. This is often dictated by transfer service role or specific needs of an individual patient. Equipment may include blood products and specific drugs (e.g. antivenoms, antidotes, drugs not usually carried by team but required by patient). Consider access to blood products from transfer team bases if blood is used frequently, as well as preparation of ‘massive transfusion packs’. Larger items such as neonatal transport cots (Figure 12.9), intra-aortic balloon pumps or extra-corporeal membrane oxygenation (ECMO) machines may also need to be considered. This requires planning, given the weight, size, and ability to safely secure these items – some transport platforms may not be able to accommodate them. When utilising aircraft, weight is a key consideration. Additional fuel may be required for longer-range transfers, life rafts for over-water missions, and a winch for search and rescue. Careful consideration is

Figure 12.9  Neonatal transport incubator.

given to equipment when such services are designed and, the addition of any equipment, may require leaving something, or someone, behind. In rare situations, a specialist may need to travel with the patient in addition to the transfer and retrieval team. These individuals are often unfamiliar with the transfer environment and require briefing as well as specific support to ensure their safety and ability to operate effectively.

Documentation, communication, and handover Patient transfer and retrieval inherently involves the handover of patient, key clinical information and documentation between healthcare professionals.

Table 12.9  Simple oxygen calculations using one example of cylinder size Anticipated oxygen use for a transfer: (Minute volume × transfer time (‘wall to wall’ in minutes) + ventilator consumption) × 2 There are some key safety assumptions made here: ●

● ●

The transfer time is the total time from disconnection in referring hospital to connection to piped oxygen in the receiving hospital

The patient is assumed to require an FiO2 of 1.0 (‘on 100% oxygen’) The total requirement is doubled to allow for delays, breakdown, unexpected diversion, etc.

Worked example: Respiratory rate 15, tidal volume 420 ml; transfer time 90 minutes (wall to wall) Minute volume = 15 × 420 = 6.3 L MV × transfer time = 6.3 × 90 = 567 L Add safety buffer = 567 × 2 = 1134 L required for transfer Cylinder type (commonly used in transfer, UK)

Cylinder capacity (L)

CD

460

E

680

ZD

600

ZX

3040

This worked example would mean 4 × CD, 2 × E or ZD, or one ZX cylinder is required for the worked example above.

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To ensure adequate information is conveyed, many transfer and retrieval services utilise an electronic referral, tele- or video-conferencing solution to enable them to bring the referring, transferring, receiving services and any other specialists together. This creates ‘a single version of the truth’, enables shared situational awareness, the receipt of patient-specific advice by the transfer team, when required, and a way of delivering relevant updates as the transfer progresses. Transfer services should have protocols that cover handover and communication. Handover should be structured, succinct, and standardised to ensure information is not inadvertently omitted. Many services have also standardised their approach to communication – liaising with referring and receiving facilities before deployment, contacting receiving centre before departure, and then alerting the receiving centre when they are close to arrival to ensure everything is prepared for them. Documentation underpins the high-quality care and tight clinical governance of transfer and retrieval services. Many services are moving towards electronic records that interface with transfer equipment to allow contemporaneous recording of monitoring parameters and other data. Whichever method is used, a full and detailed record of the patient journey, including interventions, observations, and changes in clinical status, must be provided by the transfer team at the end of the transfer.

Tips from the field • Critically ill patients require, and should receive, high-quality care throughout their transfer journey. • Documents that guide practice (including Standard Operating Procedures, guidelines, and checklists) ensure a standardised and safe approach to care. • Careful preparation of the patient, equipment, and transfer team is vital to anticipate and successfully manage unexpected events during transfer. • Excellent closed-loop communication and the conveyance of appropriately detailed information from referring hospital to receiving hospital is essential to high-quality patient care.

Further reading Ellis D, Hooper M. Cases in Pre-Hospital and Retrieval Medicine, 1st edition. 2010. Chatswood, Australia: Churchill Livingstone. ISBN 978-072953848-8. Churchill Livingstone, Elsevier. Australia. Low A, Hulme J, et al. ABC of Transfer and Retrieval Medicine, 1st edition. 2014. United Kingdom: BMJ Books. ISBN 978-1118719756. Shirley PJ, Hearns S. Retrieval medicine: a review and guide for UK practitioners. Part 1: clinical guidelines and evidence base. Emerg Med J 2006;23:937–942. Thomas SH. Controversies in prehospital care: air medical response. Emerg Med Pract 2005;7:1–26.

PA RT 2

Providing Prehospital Trauma Care

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C H A P T E R 13

Abdominal Injury Ed Barnard1 and Keith Roberts2 1

Military Consultant in Emergency Medicine (Prehospital Emergency Medicine), Cambridge University Hospitals NHS Foundation Trust, UK East Anglian Air Ambulance, UK 2 University Hospitals Birmingham, UK

Overview By the end of this chapter you should know: • the importance of understanding abdominal anatomy and mechanism of injury

Nipple line

• the essential elements of abdominal examination • emergency treatment and triage of the patient with suspected intra-abdominal injury

Introduction Abdominal injury is present in up to 40% of major trauma cases: the majority are a result of road traffic collisions and falls from height. Abdominal injuries are frequently associated with significant injury in other body regions. Diagnosis of abdominal injury in the prehospital setting is challenging, and relies on a sound underpinning knowledge, coupled with a high index of suspicion in order to recognise injury and manage appropriately.

Anatomy The surface anatomy of the abdomen should be considered from all aspects: anteriorly it extends from the 4th intercostal space (nipple line) to the groin creases, posteriorly from the tips of the scapulae to the gluteal skin creases, and laterally to connect these landmarks (Figure 13.1). Internally, the abdomen can be divided into three: the peritoneum (with a large component behind the rib cage), the retroperitoneum, and the pelvic space. In defining groups of organs within these compartments, differentiation can be made between solid organs (liver, spleen, kidneys, adrenals, pancreas), hollow-viscus organs (stomach, small bowel, colon, gall bladder, ureters, bladder) and blood vessels (inferior vena cava, aorta, superior mesenteric artery, etc.). The size and position of abdominal organs is in part responsible for the expected relative frequency of injury, which can be further understood in the context of mechanism of injury. For example, the

ABC of Prehospital Emergency Medicine, Second Edition. Edited by Tim Nutbeam, Matt Boylan, Caroline Leech, and Clare Bosanko. © 2023 John Wiley & Sons Ltd. Published 2023 by John Wiley & Sons Ltd.

Groin

Figure 13.1  Extent of the abdominal cavity (anterior).

size of the liver means that blunt trauma to the anterior abdomen is most likely to result in hepatic injury, whereas trauma to the flank is most likely to result in renal injury.

Mechanism of injury This is best separated into blunt and penetrating. In the UK, blunt abdominal trauma (BAT) predominates with penetrating injury accounting for