Ebook The walls manual of emergency airway management: Part 1

FIFTH EDITION

THE WALLS MANUAL OF
EMERGENCY AIRWAY
MANAGEMENT

EDITOR-IN-CHIEF

Calvin A. Brown III, MD
Assistant Professor of Emergency Medicine
Director of Faculty Affairs
Department of Emergency Medicine
Brigham and Women’s Hospital
Harvard Medical School
Boston, Massachusetts

ASSOCIATE EDITORS

John C. Sakles, MD
Professor
Department of Emergency Medicine
University of Arizona College of Medicine
Tucson, Arizona

Nathan W. Mick, MD, FACEP
Associate Professor
Department of Emergency Medicine
Tufts University School of Medicine
Associate Chief
Department of Emergency Medicine

Maine Medical Center
Portland, Maine


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Fifth edition
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Library of Congress Cataloging-in-Publication Data
Names: Brown, Calvin A., III, editor. | Sakles, John C., editor. | Mick, Nathan W., editor.
Title: The Walls manual of emergency airway management / editor-in-chief,
Calvin A. Brown III, MD, assistant professor of Emergency Medicine,

Director of Faculty Affairs, Brigham and Women’s Hospital, Harvard Medical
School, Boston, Massachusetts ; associate editors, John C. Sakles, MD,
professor, Department of Emergency Medicine, University of Arizona
College of Medicine, Tucson, Arizona, Nathan W. Mick, MD, associate
professor, Tufts University School of Medicine, associate chief,
Department of Emergency Medicine, Maine Medical Center, Portland, Maine.
Other titles: Manual of emergency airway management.
Description: Fifth edition. | Philadelphia : Wolters Kluwer, [2018] | Revised
edition of: Manual of emergency airway management / editors, Ron Walls,
Michael Murphy, 4th edition, 2012. | Includes bibliographical references and index.
Identifiers: LCCN 2017012521 | ISBN 9781496351968 (paperback)
Subjects: LCSH: Respiratory emergencies—Handbooks, manuals, etc. |
Respiratory intensive care—Handbooks, manuals, etc. | Airway
(Medicine)—Handbooks, manuals, etc. | BISAC: MEDICAL / Emergency Medicine.
Classification: LCC RC735.R48 M36 2018 | DDC 616.2/00425—dc23 LC record available at
/>ISBN-13: 978-1-4963-5199-9
Cataloging-in-Publication data available on request from the Publisher.


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Dedication

This book is dedicated to four pioneers in emergency medicine (left to right): Drs.
Robert Schneider, Ron Walls, Mike Murphy and Robert Luten. Their vision and
tireless devotion to education led to the creation of The Difficult Airway Course and
this comprehensive text of emergency airway management. They have defined and
refined safe, evidence-based airway management practices for generations of
emergency providers and, in the process, have saved countless lives.”


Preface

I

t is with pride and immense joy that we present this fifth edition of The Walls
Manual of Emergency Airway Management, from here on known simply as “The
Walls Manual.” This book has been extensively updated from cover to cover and
expanded with exciting new chapters. It contains the latest in evidence-based
approaches to airway management presented in a practical, yet creative style by our
highly talented authors, who teach with us in The Difficult Airway Course:
Emergency and The Difficult Airway Course: Anesthesia, The Difficult Airway
Course: Critical Care and The Difficult Airway Course: EMS. As with previous

editions, each topic has undergone a critical appraisal of the available literature to
ensure the content is on the vanguard of clinical medicine.
New information sparks vigorous debate and oftentimes a departure from
previous thinking. To this end, the fifth edition contains several fundamental changes.
The seven Ps of rapid sequence intubation (RSI), unadulterated fixtures in previous
editions, have undergone a transformative change with the elimination of Pretreatment
as a discrete pharmacologic action, now replaced by Preintubation Optimization.
With new information surfacing about the hemodynamic consequences of RSI in
critically ill emergency department patients, this new step emphasizes the importance
of maximizing cardiopulmonary physiology prior to induction and positive pressure
ventilation in order to prevent hypoxic insult and circulatory collapse. A new chapter
on intubating the unstable patient dovetails nicely with this approach and provides a
solid framework that addresses the metabolic, physiologic, and hemodynamic factors
that make emergency airway management complex and challenging. Cutting-edge
information on flush flow rate oxygen for emergency preoxygenation provides us with
new insight and options for maximizing the safety of RSI. Lidocaine, previously
advocated as a pretreatment agent for patients with elevated intracranial pressure and
reactive airways disease, no longer plays a role and has been removed from our
lexicon; however, fentanyl remains as a sympatholytic option in patients with
hypertensive crises, although is now considered part of a holistic approach to
cardiovascular optimization and is no longer thought of as an independent
pharmacologic maneuver. We present updated mnemonics for difficult airway
detection with the “MOANS” mnemonic for difficult bag and mask ventilation
refreshed to create “ROMAN,” which better highlights our newly understood
association between radiation changes (the “R” in ROMAN) and difficult bagging. In


addition, we cover the latest in airway tools as old standbys like the GlideScope and
C-MAC videolaryngoscopes continue to transform into more streamlined and
affordable devices with improved image quality and overall performance.

This compendium embodies what we believe to be the knowledge and skill set
required for emergency airway management in both the emergency department and the
prehospital environment. The principles, however, are applicable to a wide array of
clinical settings. As inpatient care continues to evolve and roles become redefined,
we are witnessing the emergence of hospitalists and critical care physicians as
primary airway managers being called upon frequently to intubate on hospital floors
and in intensive care units. The concepts we present in the fifth edition can be
extrapolated to any arena where urgent airway management might take place and is as
relevant to inpatient clinicians as it is to emergency medicine specialists. Tapping yet
again into Terry Steele’s vision and creativity, we drew upon the combined
knowledge base from both the anesthesia and emergency medicine courses to develop
The Difficult Airway Course: Critical Care in 2016, a comprehensive and robust new
curriculum to meet the educational needs of this unique group of airway managers.
New chapters on intubating the unstable patient and safe extubation techniques
augments this new curriculum and helps to make this latest edition the most versatile
manual ever.
We are fortunate for the opportunity to provide this resource and are hopeful that
the material in this book will play an important role when, late at night, faced with
little information, less help, and virtually no time for debate we are called to act,
make extraordinary decisions, and save lives.
Calvin A. Brown III, MD
Boston, Massachusetts
John C. Sakles, MD
Tucson, Arizona
Nathan W. Mick, MD, FACEP
Portland, Maine


Acknowledgments
One of the most precious gifts in medicine is that of mentorship and I have been

fortunate beyond measure. My development as an academic emergency physician
would not have been possible without the frequent advice, incredible opportunities,
and genuine friendship from Dr. Ron Walls. While professional aspirations are
important, family is paramount. I must thank my wife Katherine and our two
wonderful boys, Calvin and Caleb. Their steadfast love and support despite years of
travel and long office hours has provided me with the privilege to pursue my
professional goals. Finally, I would like to acknowledge the national teaching faculty
of our airway courses as well as the faculty, residents, and medical students at
Brigham and Women’s Hospital and Harvard Medical School who help keep me
energized, challenged, and intellectually honest on a daily basis.

Calvin A. Brown III, MD
Boston, Massachusetts
There are many people in my life, including my family, professional colleagues, and
patients, who have greatly enriched my career and have made my participation in the
airway course and manual possible. I thank them all for their understanding,
continued support, and faith in me. I would like to dedicate this manual to all the
frontline providers, of every specialty and discipline, who manage the airways of
critically ill and injured patients. It is through their tireless efforts, working in
uncontrolled environments and under difficult circumstances, that the lives of our
loved ones are saved.

John C. Sakles, MD
Tucson, Arizona
Ten years ago, I was contacted by Dr. Ron Walls asking if I would be available to
help teach at the Difficult Airway Course and it was with great honor and pleasure
that I accepted his offer. Today, I remain immensely grateful to him for his teaching
and mentorship during residency and in the early portion of my academic career. A
decade has passed, and I feel blessed to have interacted with such an amazing group

of airway educators and often feel as if I have received as much as I have given
during those long weekends. A special thanks to Dr. Bob Luten, who has a special
place in my heart as one of the founding fathers of Pediatric Emergency Medicine and
a true pioneer in pediatric airway management. Thank you as well to my family, wife
Kellie, daughters Gracyn and Afton, for putting up with the frequent travel, with only
the occasional “snow globe” present on my return. Know that time away from the
family is never easy, but we feel we are truly making a difference.

Nathan W. Mick, MD, FACEP
Portland, Maine


Contributors
Jennifer L. Avegno, MD
Clinical Assistant Professor of Medicine
Section of Emergency Medicine
Louisiana State University Health Sciences Center
New Orleans, Louisiana

Aaron E. Bair, MD
Professor
Department of Emergency Medicine
University of California Davis School of Medicine
Sacramento, California

Jeff Birrer, EMT-P
Paramedic
American Medical Response
Portland, Oregon

Darren A. Braude, MD
Paramedic Chief
Division of Prehospital, Austere, and Disaster Medicine
Professor of Emergency Medicine and Anesthesiology
University of New Mexico Health Sciences Center
Medical Director, The Difficult Airway Course: EMS
Albuquerque, New Mexico

Calvin A. Brown III, MD
Assistant Professor of Emergency Medicine
Director of Faculty Affairs
Department of Emergency Medicine
Brigham and Women’s Hospital
Harvard Medical School
Boston, Massachusetts

Stephen Bush, MA (Oxon), FRCS, FRCEM
Consultant in Emergency Medicine
Emergency Department
Leeds Teaching Hospitals Trust
United Kingdom

Steven C. Carleton, MD, PhD
Professor
W. Brian Gibler Chair of Emergency Medicine Education


Department of Emergency Medicine
University of Cincinnati College of Medicine

Cincinnati, Ohio

David A. Caro, MD
Associate Professor
Department of Emergency Medicine
University of Florida College of Medicine
Jacksonville, Florida

Ken Davis EMT-P, FP-C, BA
EMSRx LLC
Waxahachie, Texas

Peter M.C. DeBlieux, MD
Professor of Clinical Medicine
Section of Emergency Medicine
Louisiana State University Health Sciences Center
University Medical Center New Orleans
New Orleans, Louisiana

Brian E. Driver, MD
Assistant Professor
Department of Emergency Medicine
University of Minnesota Medical School
Faculty Physician
Department of Emergency Medicine
Hennepin County Medical Center
Minneapolis, Minnesota

Laura V. Duggan, MD
Clinical Associate Professor

Department of Anesthesiology, Pharmacology, and Therapeutics
University of British Columbia
Vancouver, British Columbia, Canada

Jan L. Eichel, RN, CFRN, BA, EMT-P
Director of Clinical Operations
West Michigan Air Care
Kalamazoo, Michigan

Frederick H. Ellinger, Jr., NRP
Flight Paramedic
MidAtlantic MedEvac
AtlantiCare Regional Medical Center
Atlantic City, New Jersey


Megan L. Fix, MD
Assistant Professor
Division of Emergency Medicine
University of Utah Hospital
Salt Lake City, Utah

Kevin Franklin, RN, EMT-P, CFRN
Flight Nurse
West Michigan Air Care
Kalamazoo, Michigan

Michael A. Gibbs, MD
Professor and Chairman
Department of Emergency Medicine

Carolinas Medical Center
Levine Children’s Hospital
Charlotte, North Carolina

Steven A. Godwin, MD, FACEP
Professor and Chair
Department of Emergency Medicine
University of Florida College of Medicine
Jacksonville, Florida

Michael G. Gonzalez, MD, FACEP, FAAEM
Assistant Professor
Emergency Medicine
Baylor College of Medicine
Associate Medical Director
Houston Fire Department
Houston, Texas

Alan C. Heffner, MD
Director of Critical Care
Director of ECMO Services
Professor
Department of Internal Medicine
Department of Emergency Medicine
Carolinas Medical Center
University of North Carolina
Charlotte, North Carolina

Cheryl Lynn Horton, MD
Associate Physician

Department of Emergency Medicine
Kaiser Permanente East Bay


Oakland, California

Andy S. Jagoda, MD
Professor and System Chair
Department of Emergency Medicine
Icahn School of Medicine at Mount Sinai
New York, New York

Michael Keller, BS, NRP
Curriculum Faculty
Department for EMS Education
Gaston College
Dallas, North Carolina

Erik G. Laurin MD
Professor
Department of Emergency Medicine
Vice Chair for Education
University of California, Davis, School of Medicine
Sacramento, California

Robert C. Luten, MD
Professor
Department of Emergency Medicine
Division of Pediatric Emergency Medicine
University of Florida College of Medicine

Jacksonville, Florida

Nathan W. Mick, MD, FACEP
Associate Professor
Tufts University School of Medicine
Associate Chief
Department of Emergency Medicine
Maine Medical Center
Portland, Maine

Jarrod M. Mosier, MD
Associate Professor
Department of Emergency Medicine
Department of Medicine
Division of Pulmonary, Allergy, Critical Care, and Sleep
University of Arizona College of Medicine
Tucson, Arizona

Michael F. Murphy MD, FRCPC
Professor Emeritus


University of Alberta
Edmonton, Alberta, Canada

Joshua Nagler, MD, MHPEd
Assistant Professor
Harvard Medical School
Division of Emergency Medicine
Boston Children’s Hospital

Boston, Massachusetts

Justen Naidu, MD
Anesthesiology Resident
Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia
Vancouver, British Columbia, Canada

Bret P. Nelson, MD
Associate Professor
Department of Emergency Medicine
Icahn School of Medicine at Mount Sinai
New York, New York

Ali S. Raja, MD, MBA, MPH
Vice Chairman and Associate Professor
Department of Emergency Medicine
Massachusetts General Hospital
Harvard Medical School
Boston, Massachusetts

Robert F. Reardon, MD
Professor of Emergency Medicine
University of Minnesota Medical School
Department of Emergency Medicine
Hennepin County Medical Center
Minneapolis, Minnesota

John C. Sakles, MD
Professor
Department of Emergency Medicine

University of Arizona College of Medicine
Tucson, Arizona

Leslie V. Simon, DO
Assistant Professor
Department of Emergency Medicine
Mayo Clinic Florida
Jacksonville, Florida


Mary Beth Skarote, EMT-P, LPN
All Hazards Planner
Veteran Corps of America
Jacksonville, North Carolina

Julie A. Slick, MD
Assistant Professor
Louisiana State University Health Sciences Center
Chief, Emergency Medicine
Southeast Louisiana Veterans Health Care System
New Orleans, Louisiana

Michael T. Steuerwald, MD
Assistant Professor
Department of Emergency Medicine
University of Wisconsin School of Medicine and Public Health
Madison, Wisconsin

Eli Torgeson, MD
Assistant Professor

Department of Anesthesiology and Critical Care Medicine
University of New Mexico School of Medicine
Albuquerque, New Mexico

Katren R. Tyler, MD
Associate Professor
Associate Residency Director
Geriatric Emergency Medicine Fellowship Director
Vice Chair for Faculty Development, Wellbeing, and Outreach
Department of Emergency Medicine
University of California Davis School of Medicine
Sacramento, California

Ron M. Walls, MD
Executive Vice President and Chief Operating Officer
Brigham and Women’s Health Care
Neskey Family Professor of Emergency Medicine
Harvard Medical School
Boston, Massachusetts

Richard D. Zane, MD
Professor and Chair
Department of Emergency Medicine
University of Colorado School of Medicine
University of Colorado Hospital
Denver, Colorado


Contents
Preface

Acknowledgments
SECTION I

PRINCIPLES OF AIRWAY MANAGEMENT

1

The Decision to Intubate
Calvin A. Brown III and Ron M. Walls

2

Identification of the Difficult and Failed Airway
Calvin A. Brown III and Ron M. Walls

3

The Emergency Airway Algorithms
Calvin A. Brown III and Ron M. Walls

4

Applied Functional Anatomy of the Airway
Michael F. Murphy

SECTION II

OXYGEN DELIVERY AND MECHANICAL VENTILATION

5

Principles of Preparatory Oxygenation
Robert F. Reardon, Brian E. Driver, and Steven C. Carleton

6

Noninvasive Mechanical Ventilation
Alan C. Heffner and Peter M.C. DeBlieux

7

Mechanical Ventilation
Alan C. Heffner and Peter M.C. DeBlieux

8

Oxygen and Carbon Dioxide Monitoring
Robert F. Reardon and Jennifer L. Avegno


SECTION III

BASIC AIRWAY MANAGEMENT

9

Bag-Mask Ventilation
Steven C. Carleton, Robert F. Reardon, and Calvin A. Brown III

10

Extraglottic Devices: Supraglottic Type
Michael F. Murphy and Jennifer L. Avegno

11

Extraglottic Devices: Retroglottic Type
Erik G. Laurin, Leslie V. Simon, Darren A. Braude, and Michael F. Murphy

12

Managing the Patient with an Extraglottic Device in Place
Darren A. Braude, Michael T. Steuerwald, and Eli Torgeson

SECTION IV

TRACHEAL INTUBATION

13

Direct Laryngoscopy
Robert F. Reardon and Steven C. Carleton

14

Video Laryngoscopy
John C. Sakles and Aaron E. Bair

15

Optical and Light-Guided Devices
Julie A. Slick

16

Flexible Endoscopic Intubation
Alan C. Heffner and Peter M.C. DeBlieux

17

Fiberoptic and Video Intubating Stylets
Cheryl Lynn Horton and Julie A. Slick

18

Blind Intubation Techniques
Michael T. Steuerwald, Darren A. Braude, and Steven A. Godwin

19

Surgical Airway Management
Aaron E. Bair and David A. Caro


SECTION V
PHARMACOLOGY AND TECHNIQUES OF AIRWAY
MANAGEMENT
20

Rapid Sequence Intubation

Calvin A. Brown III and Ron M. Walls

21

Sedative Induction Agents
David A. Caro and Katren R. Tyler

22

Neuromuscular Blocking Agents
David A. Caro and Erik G. Laurin

23

Anesthesia and Sedation for Awake Intubation
Alan C. Heffner and Peter M.C. DeBlieux

SECTION VI

PEDIATRIC AIRWAY MANAGEMENT

24

Differentiating Aspects of the Pediatric Airway
Robert C. Luten and Nathan W. Mick

25

Pediatric Airway Techniques
Robert C. Luten, Steven A. Godwin, and Nathan W. Mick

26

The Difficult Pediatric Airway
Joshua Nagler and Robert C. Luten

27

Foreign Body in the Pediatric Airway
Robert C. Luten and Joshua Nagler

SECTION VII

EMS AIRWAY MANAGEMENT

28

Introduction to EMS Airway Management
Frederick H. Ellinger Jr, Michael Keller, and Darren A. Braude

29

Techniques in EMS Airway Management
Kevin Franklin, Darren A. Braude, and Michael G. Gonzalez


30

Difficult and Failed Airway Management in EMS
Jan L. Eichel, Mary Beth Skarote, and Darren A. Braude

31

Controversies in EMS Airway Management
Jeff Birrer, Ken Davis, and Darren A. Braude

SECTION VIII

SPECIAL CLINICAL CIRCUMSTANCES

32

The Unstable Patient: Cardiopulmonary Optimization for Emergency
Airway Management
Jarrod M. Mosier, Alan C. Heffner, and John C. Sakles

33

The Trauma Patient
Michael A. Gibbs, Ali S. Raja, and Michael G. Gonzalez

34

Elevated ICP and HTN Emergencies
Bret P. Nelson and Andy S. Jagoda

35

Reactive Airways Disease
Bret P. Nelson and Andy S. Jagoda

36

Distorted Airways and Acute Upper Airway Obstruction
Ali S. Raja and Erik G. Laurin

37

The Pregnant Patient
Richard D. Zane and Cheryl Lynn Horton

38

The Patient with Prolonged Seizure Activity
Stephen Bush and Cheryl Lynn Horton

39

The Geriatric Patient
Katren R. Tyler and Stephen Bush

40

The Morbidly Obese Patient
Megan L. Fix and Richard D. Zane


41

Foreign Body in the Adult Airway

Ron M. Walls and Erik G. Laurin

42

Safe Extubation of the Emergency Patient
Justen Naidu and Laura V. Duggan

Index


Section I
Principles of Airway Management
1 The Decision to Intubate
2 Identification of the Difficult and Failed Airway
3 The Emergency Airway Algorithms
4 Applied Functional Anatomy of the Airway


Chapter 1
The Decision to Intubate
Calvin A. Brown III and Ron M. Walls
INTRODUCTION
Airway management is constantly evolving. The emergence of new technology,
principally the various methods of video laryngoscopy, our understanding of
contributors to intubation difficulty, and a renewed focus on oxygenation and
cardiovascular stability during airway management are changing our fundamental
decision-making in an effort to maximize patient safety and outcome. What has not
changed, however, is the critical importance of the determination of whether a patient
requires intubation and, if so, how urgently. The decision to intubate is the first step
in emergency airway management, and sets in motion a complex series of actions

required of the clinician, before performing the actual intubation:
Rapidly assess the patient’s need for intubation and the urgency of the situation.
Determine the best method of airway management based on assessment of the
patient’s predicted difficulty and pathophysiology.
Decide which pharmacologic agents are indicated, in what order, and in what
doses.
Prepare a plan in the event that the primary method is unsuccessful, know in
advance how to recognize when the planned airway intervention has failed or
will inevitably fail, and clearly lay out the alternative (rescue) technique(s).
Clinicians responsible for emergency airway management must be proficient with the
techniques and medications used for rapid sequence intubation (RSI), the preferred
method for most emergency intubations, as well as alternative intubation strategies
when neuromuscular blockade is contraindicated. The entire repertoire of airway


skills must be mastered, including bag-mask ventilation, video laryngoscopy,
conventional laryngoscopy, flexible endoscopy, the use of extraglottic airway
devices, adjunctive techniques such as use of an endotracheal tube introducer (also
known as the gum elastic bougie), and surgical airway techniques (e.g., open or
Seldinger-based cricothyrotomy).
This chapter focuses on the decision to intubate. Subsequent chapters describe
airway management decision-making, methods of ensuring oxygenation, techniques
and devices for airway management, the pharmacology of RSI, and considerations for
special clinical circumstances, including the prehospital environment and care of
pediatric patients.

INDICATIONS FOR INTUBATION
The decision to intubate is based on three fundamental clinical assessments:
1. Is there a failure of airway maintenance or protection?
2. Is there a failure of ventilation or oxygenation?

3. What is the anticipated clinical course?
The results of these three evaluations will lead to a correct decision to intubate or not
to intubate in virtually all conceivable cases.
A. Is there a failure of airway maintenance or protection?
Without a patent airway and intact protective reflexes, adequate oxygenation
and ventilation may be difficult or impossible and aspiration of gastric contents
can occur. Both expose the patient to significant morbidity and mortality. The
conscious, alert patient uses the musculature of the upper airway and various
protective reflexes to maintain patency and to protect against the aspiration of
foreign substances, gastric contents, or secretions. The ability of the patient to
phonate with a clear, unobstructed voice is strong evidence of airway patency,
protection, and cerebral perfusion. In the severely ill or injured patient, such
airway maintenance and protection mechanisms are often attenuated or lost. If the
spontaneously breathing patient is not able to maintain a patent airway, an
artificial airway may be established by the insertion of an oropharyngeal or
nasopharyngeal airway. Although such devices may restore patency, they do not
provide any protection against aspiration. Patients who are unable to maintain
their own airway are also unable to protect it. Therefore, as a general rule, any
patient who requires the establishment of a patent airway also requires protection


of that airway. The exception is when a patient has an immediately reversible
cause of airway compromise (e.g., opioid overdose) and reversal of the insult
promptly restores the patient’s ability to maintain an open, functioning airway. The
need to protect the airway requires placement of a definitive airway (i.e., a cuffed
endotracheal tube), and devices that simply maintain, but do not protect, the
airway, such as oropharyngeal or nasopharyngeal airways, are temporizing
measures only. It has been widely taught that the gag reflex is a reliable method of
evaluating airway protective reflexes. In fact, this concept has never been
subjected to adequate scientific scrutiny, and the absence of a gag reflex is neither

sensitive nor specific as an indicator of loss of airway protective reflexes. The
presence of a gag reflex has similarly not been demonstrated to ensure the
presence of airway protection. In addition, testing the gag reflex in a supine,
obtunded patient may result in vomiting and aspiration. Therefore, the gag reflex is
of no clinical value, and in fact may be dangerous to assess when determining the
need for intubation and should not be used for this purpose.
Spontaneous or volitional swallowing is a better assessment of the patient’s
ability to protect the airway than is the presence or absence of a gag reflex.
Swallowing is a complex reflex that requires the patient to sense the presence of
material in the posterior oropharynx and then execute a series of intricate and
coordinated muscular actions to direct the secretions down past a covered airway
into the esophagus. The finding of pooled secretions in the patient’s posterior
oropharynx indicates a potential failure of these protective mechanisms, and hence
a failure of airway protection. A common clinical error is to assume that
spontaneous breathing is proof that protective airway mechanisms are preserved.
Although spontaneous ventilation may be adequate, the patient may be sufficiently
obtunded to be at serious risk of aspiration.
B. Is there a failure of ventilation or oxygenation?
Stated simply, “gas exchange” is required for vital organ function. Even brief
periods of hypoxia should be avoided, if possible. If the patient is unable to
ventilate sufficiently, or if adequate oxygenation cannot be achieved despite the
use of supplemental oxygen, then intubation is indicated. In such cases, intubation
is performed to facilitate ventilation and oxygenation rather than to establish or
protect the airway. An example is the patient with status asthmaticus, for whom
bronchospasm and fatigue lead to ventilatory failure and hypoxemia, heralding
respiratory arrest and death. Airway intervention is indicated when it is
determined that the patient will not respond sufficiently to treatment to reverse
these cascading events. Similarly, although the patient with severe acute
respiratory distress syndrome may be maintaining and protecting the airway, he or