emac participants manual 2010-1
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EMAC manualTRANSCRIPT
EFFECTIVE
MANAGEMENT OF
ANAESTHETIC CRISES
PARTICIPANT MANUAL SECOND EDITION 2010
©ANZCA
ii
iii
EMAC EFFECTIVE MANAGEMENT OF ANAESTHETIC
CRISES
SECOND EDITION 2010
Editor Assoc Prof Sandy Garden FANZCA
Contributors Assoc Prof Brendan Flanagan FANZCA
Assoc Prof Sandy Garden FANZCA
Dr Tim Gray FACEM
Dr Stuart Marshall FANZCA
Dr Richard Morris FANZCA
Dr Adam Rehak FANZCA
Assoc Leonie Watterson FANZCA
Assoc Prof Jennifer Weller FANZCA
Acknowledgement Assoc Prof Brian Robinson PhD (proof-reading)
© AUSTRALIAN AND NEW ZEALAND
COLLEGE OF ANAESTHETISTS
iv
Published in 2010 by
Australian and New Zealand College of Anaesthetists,
630 St Kilda Road
Melbourne Victoria 3004
Australia
v
CONTENTS
INTRODUCTION TO FIRST EDITION ......................................................................................................... VI
INTRODUCTION TO SECOND EDITION ................................................................................................... VII
HUMAN PERFORMANCE ISSUES ................................................................................................................... 1
OVERVIEW ........................................................................................................................................................... 1 GENERIC PRINCIPLES FOR PREVENTION & MANAGEMENT OF DIFFICULT CLINICAL SITUATIONS ........................ 5 GABA‟S SEVEN “KEY POINTS” FOR PREVENTING & MANAGING CRITICAL EVENTS ............................................ 5 PERFORMANCE-SHAPING FACTORS, INCLUDING PRODUCTION PRESSURE ........................................................... 8 TEAMWORK ISSUES: SOCIAL PSYCHOLOGY OF THE OPERATING THEATRE ....................................................... 12 SUMMARY ......................................................................................................................................................... 13
CARDIOVASCULAR EMERGENCIES .......................................................................................................... 15
OVERVIEW ......................................................................................................................................................... 15 MYOCARDIAL ISCHAEMIA & ACUTE CORONARY SYNDROMES.......................................................................... 16 CARDIAC ARREST & POST-ARREST CARE ......................................................................................................... 19 CARDIOVERTER/DEFIBRILLATORS ..................................................................................................................... 29 CRISES WITH VALVULAR HEART DISEASE ......................................................................................................... 32 HYPERTENSIVE CRISES ...................................................................................................................................... 33 PERIOPERATIVE STROKE .................................................................................................................................... 33 EMERGENCY VASCULAR ACCESS ...................................................................................................................... 33
AIRWAY EMERGENCIES ............................................................................................................................... 37
OVERVIEW ......................................................................................................................................................... 37 THE PRIMARY PLAN FOR AIRWAY MANAGEMENT ............................................................................................ 38 CONTINGENCY PLANS ....................................................................................................................................... 41 EMERGENCY PLANS ........................................................................................................................................... 44 UPPER AIRWAY OBSTRUCTION .......................................................................................................................... 45 IMPAIRED GAS EXCHANGE ASSOCIATED WITH A PATENT AIRWAY .................................................................. 49 SUMMARY ......................................................................................................................................................... 50 APPENDIX 1 : DIFFICULT AIRWAY SOCIETY ALGORITHMS ................................................................................ 51 APPENDIX 2 : SURGICAL AIRWAY ANATOMY ................................................................................................... 54
ANAESTHETIC EMERGENCIES ................................................................................................................... 59
OVERVIEW ......................................................................................................................................................... 59 AN IMMEDIATE RESPONSE TO A CRISIS ............................................................................................................. 60 DEVELOPING SKILLS IN A WORKING TEAM ....................................................................................................... 60 BEHAVIORAL STRATEGIES TO IMPROVE DIAGNOSIS .......................................................................................... 61 A SYSTEMATIC APPROACH TO CRISIS MANAGEMENT ....................................................................................... 62 SUMMARY ......................................................................................................................................................... 63 APPENDICES ...................................................................................................................................................... 64
THE MANAGEMENT OF TRAUMA .............................................................................................................. 70
OVERVIEW ......................................................................................................................................................... 71 INITIAL MANAGEMENT ...................................................................................................................................... 71 PRIMARY SURVEY ............................................................................................................................................. 71 RESUSCITATION ................................................................................................................................................. 72 SECONDARY SURVEY ........................................................................................................................................ 72 EVOLVING INJURIES........................................................................................................................................... 73 HAND-OVER OF CARE ........................................................................................................................................ 73 MANAGEMENT OF LARGE-VOLUME RESUSCITATION ......................................................................................... 73 ANAESTHETIC IMPLICATIONS OF AIRWAY TRAUMA .......................................................................................... 74 ANAESTHETIC IMPLICATIONS OF CHEST TRAUMA ............................................................................................. 76 INTRA-CRANIAL TRAUMA .................................................................................................................................. 76 X-RAYS IN THE TRAUMA SETTING .................................................................................................................... 77
vi
Introduction to First Edition The Concise Oxford Dictionary defines
effective as “actually useful”. Crisis comes
from the Greek krisis meaning decision and is
defined as “time of danger” or as a “time of
decision”.
Effective Management of Anaesthetic Crises
(EMAC) is a course intended to provide
practical techniques in the management of
anaesthetic emergencies. Anaesthesia alone
could be described as a time of danger. In no
other human activity are seemingly healthy
individuals rendered unconscious, paralysed
and deprived of their usual respiratory or
cardiovascular control mechanisms. The
anaesthetist takes over the decision making
from the individual’s homeostatic control
centres. The onset of danger is relative to a
threshold. This could range from when one
physiological variable falls outside the healthy
range to when the anaesthetist cannot
simultaneously administer the drugs on behalf
of the vasomotor centre, monitor end-tidal
gases for the respiratory centre and put in a
necessary central line. This course does not
establish these thresholds; they are dependent
on many factors and beyond the scope of a two
and a half-day course. Instead, EMAC focuses
on how a crisis can be recognised and
subsequently managed.
The aviation industry has recognised that
simply knowing what needs to be done in an
emergency may not avoid disaster and specific
training in how to deal with emergencies is
now standard practice. Throughout training,
anaesthetists are taught many anaesthetic skills
and on completion of their fellowship have a
thorough knowledge of what must be done in
an emergency. EMAC follows the lead made
in other industries and focuses on how
anaesthetists can utilise their existing
knowledge and enable this knowledge to be
applied effectively in a crisis.
EMAC brings a significant new approach to
medical training that emphasises the
behavioural aspects of managing anaesthetic
crises. Effective management of emergencies,
particularly in aviation, is now recognised to
hinge on the behavioural aspects of leadership
and the interaction with a team. There is
growing recognition that the surgical and
anaesthetic staff in an operating room similarly
work as a team, particularly during
emergencies. EMAC focuses on the role of the
anaesthetist as the leader of this team during an
anaesthetic crisis and the interaction with the
people around the anaesthetist to use their
skills and resources effectively. In addition,
this course develops the behavioural strategies
to facilitate decision making and encourages
the use of protocols during anaesthetic
emergencies.
Brian Robinson
February 2001
vii
Introduction to Second Edition The EMAC Course represents an on-going
endeavour by a group of medical and non-
medical experts who are committed to
improving the management of crises in the
domain of anaesthesia as well as in other
domains of acute patient care.
The course materials represent the expert
opinion of the authors and those who attended
a series of editorial workshops held during
2009. As such the teaching materials represent
the opinions are those individuals, rather than
the opinion of ANZCA.
A number of illustrations have been
reproduced in these manuals within the terms
of ANZCA’s Education Licence. ANZCA
thanks the original authors and publishers who
allowed these materials to be reproduced.
As the President of ANZCA, I thank all those
who have contributed to the evolution of this
course and these educational materials,
particularly those who wrote these materials.
Leona Wilson
President
Australian and New Zealand College of
Anaesthetists.
January 2010
Human Performance Issues
1
Human Performance Issues
Dr Stuart Marshall
Assoc Prof Brendan Flanagan
This module aims to increase understanding of
the various means by which the performance
of anaesthetic practitioners - as individuals and
as part of a health care team - can impact on
patient care.
Objectives
Understand the psychology of human
performance in anaesthesia
Understand generic principles of crisis
prevention and management
Recognise performance-shaping factors,
including production pressure
Understand the concept of a systems
approach to patient safety
Overview
Why Focus on Human Performance Issues?
There has been an explosion of interest in the
issue of human performance in high-risk
industries during the past 5-10 years. “As
hardware and software solutions have become
more reliable, the human contributions to
safety have become ever more apparent” 1 p1.
Anaesthesia is acknowledged as the leading
medical specialty in addressing issues relating
to human performance in healthcare, and in
patient safety initiatives in general. Some of
the strategies that anaesthesia has introduced
include:
Incorporating new technologies.
Introduction of standards & guidelines.
Addressing problems relating to “human
factors” and “system” issues.
Despite these changes, the domain of the
anaesthetist remains very challenging.
Anaesthesia continues to be a unique specialty
in terms of the common occurrence of
conditions that challenge optimum human
performance. The anaesthesia practitioner
must perform almost flawlessly despite:
Less than ideal environmental conditions
such as poor light, noise, or ambient
temperature.
Distractions, such as alarms and multiple
tasks.
Often conflicting objectives with
inadequate information available to
support optimal decision-making.
The aim of this module is to increase
understanding of the significance of the
performance of the anaesthetist - as an
individual and as part of a team - on patient
care. Increased awareness of these issues may
impact positively on patient care and outcome.
We hope to draw on your experiences to
enable us all to gain new insights into these
matters.
Human Performance Issues
2
Firstly, what are the pros & cons of having
humans involved in the system of delivery of
anaesthesia?
Human beings are not machines. When
maintained, machines are generally very
predictable and reliable, whereas humans are
unpredictable and unreliable, and our ability to
process information is limited by the capacity
of our (working) memory. However, in regard
to decision-making, the performance of human
beings is incredibly creative, flexible and
powerful - in ways that no computer can
match. Conversely, human performance is
vulnerable to distractions, biases and errors.
Distractibility is both a strength and a
weakness. It helps us notice when something
unusual is happening, and we are very good at
recognising and responding to situations
rapidly, and adapting to new situations and
new information. But our ability to be
distracted also predisposes us to error, because
when distracted we may not pay attention to
the most important aspects of a task or
situation. Our brain can also play „tricks‟ on
us, by misperceiving a situation – one of the
main reasons that making errors is a
fundamental and inevitable feature of the
human condition. Humans are very poor at
“multi-tasking”, that is trying to concentrate on
and perform more than one task at a time -
however computers are very good at this!
Humans possess the big advantage of being
able to recall past experiences in order to
perceive a problem and develop a solution. By
comparison, current computers can only deal
with situations for which they have been
programmed (by humans!). However,
machines (computers) never get tired, always
do things the same way and do not suffer from
bias in association with previous experience!
In summary, human factors psychologists
agree that optimum performance in complex,
dynamic fields such as anaesthesia requires an
appropriate combination of man and machine.
A fundamental premise underlying the
rationale for this module is that To Err is
Human. In fact this is the title of a landmark
patient safety document released in the U.S.A.
in December, 1999 and which has led to
sweeping changes in the way that patient
safety is perceived in health-care.
The reality that humans “err”, results from the
physiological & psychological limitations of
human performance. Contributors to error
include:
Fatigue
Workload
Fear of blame
Mental overload
Poor interpersonal communications
Imperfect information processing
Flawed decision-making
Unfortunately, doctors tend to overestimate
their ability to function flawlessly under
adverse conditions, such as under the pressures
of time, fatigue, or high anxiety. An important
consideration is that the problem of medical
“error” is not fundamentally due to lack of
knowledge. Many adverse events in medicine
result from actions made by persons who know
how to perform the relevant task safely, have
done so many times in the past - and face
significant personal consequences of the
action!
We will explore some of these issues in more
detail in this module.
Individual Performance
Psychology of Human Performance in
Anaesthesia
This section is predominantly a distillation of
the introductory section from Crisis
Management in Anesthesiology 2 and has been
undertaken with the permission of the authors.
You are strongly encouraged to read the first
two chapters of that book and the more recent
and related Chapter 83 in Miller‟s Anesthesia 3.
The practice of anaesthesia is a complicated
collection of mental and physical activities
attuned more to the efficient care of routine
cases than to the handling of life-threatening
crises. How newcomers to anaesthesia become
skilled practitioners is only recently beginning
to be understood, and the fundamental question
of what is meant by “expertise” in anaesthesia
is only now starting to be explored.
Experience of challenging situations plays a
significant role in the development of expertise
– as does, it is theorised, „deliberate practice‟
afforded by exposure to simulated
emergencies. Despite this we have discovered
that initial training and continuing education
often leave substantial gaps in the ability of
Human Performance Issues
3
some anaesthetists to deal with crises. When a
critical incident does occur, it is apparent to
everyone who works in an operating theatre
that some anaesthetists cope better than others.
They are the ones who can restore order in the
midst of chaos, who know what to do, and how
to get it done. They can make and execute
good decisions and manage people. In short,
they are the ones we would want to give our
anaesthetic!
Why are some seemingly better than others
at this, and can these skills be learned and
taught?
As a specialty we are only beginning to
examine these issues, perhaps because until
recent times we have erroneously thought of
anaesthesia practise in terms of more
traditional forms of medicine. In fact, some of
the dominant features of our work -
complexity, uncertainty, time-pressure,
“dynamism” (i.e. things can happen very
quickly sometimes!) - share more in common
with industries such as aviation, nuclear power
and fire-fighting than they do with other forms
of medicine. We are beginning to understand
the mindset of the anaesthetist better by
looking at research findings from these other
fields. In fact there are several successful
safety strategies in aviation that could be
incorporated into anaesthesia, though this has
yet to happen systematically.
These include:
Use of written checklists to help prevent
crises from occurring e.g. anaesthesia
machine checklist.
Use of established procedures (both
memorised & written), for responding to
crises e.g. algorithms 4.
Training in decision-making & operating
team co-ordination.
Systematic practice in the handling of
crisis situations (including the use of
immersive simulation training).
Anaesthetists who adopt many of these
strategies will enhance patient safety through
improved performance.
The remainder of this section is intended to
provide an introduction to the psychological
issues involved in optimal performance by
anaesthetists.
Anaesthetists are required to make both routine
and complex decisions regarding patient care
during the intraoperative period. There is also
a variety of tasks with varying degrees of
complexity that need to be performed. Expert
performance in anaesthesia involves a repeated
loop of observation, decision, action & re-
evaluation. Gaba describes the anaesthetist‟s
mental activities operating at several levels
almost simultaneously.
At a sensorimotor level, activities
involving sensory perception or motor
actions take place with minimal conscious
control, e.g. squeezing the bag to ventilate
the patient.
At a procedural level, the anaesthetist
performs regular subroutines that have
been derived from previous work
episodes, e.g. switching to 100% O2 and
from ventilator to hand ventilation in
response to a falling O2 saturation.
A level of abstract reasoning is used
primarily in unfamiliar situations for
which no well-practiced expertise is
available from previous encounters. e.g.
thinking through the causation &
management of refractory hypotension
Supervisory control is concerned with
dynamic allocation of the anaesthetist‟s
finite attention to routine and non-routine
actions, e.g. using a regular systematic
“scanning” process to ensure nothing is
being missed.
Resource management occurs at the
highest level of mental activity and deals
with the command and control of all
available resources, i.e. the ability to
translate the knowledge of what needs to
be done into effective team activity.
These last two levels involve dynamic
adaptation of the anaesthetist‟s own thought
processes. This ability to “think about one‟s
own thinking” in order to strategically control
one‟s own mental activities, is called
metacognition and is a very important part of
successful crisis management – and up until
now has not been part of traditional training.
The following points warrant consideration:
Observation: Management of dynamic
situations depends on the anaesthetist‟s
responses to many sources of rapidly changing
information. But the human mind can only
attend closely to one or two items at a time. In
Human Performance Issues
4
fact the anaesthetist‟s attention is such a scarce
resource that its allocation is extremely
important in nearly every aspect of dynamic
decision-making. Vigilance, the capacity to
sustain attention, is a necessary, but in itself
insufficient, component of decision-making
and crisis management. Human beings tolerate
boredom poorly, making it very difficult to
maintain vigilance during periods of low or
monotonous workload or prolonged inactivity.
Verification: Knowing when and how to
verify data is another important metacognitive
skill. For instance, the anaesthetist must
decide under what conditions it is appropriate
to invest time, attention and energy on
establishing a new form of monitoring, such as
placing a pulmonary artery catheter in the
middle of a case, as opposed to relying on
more indirect monitoring already in place.
Problem Recognition: Problem recognition
involves matching sets of data to patterns that
are known to represent specific types of
problems. Unfortunately the available data
streams do not always disclose the existence of
a problem, and even when a problem is
detected, the cues often do not specify its
nature or cause. Therefore, when a clear-cut
“match” or diagnosis cannot be made,
anaesthetists use approximation strategies,
termed heuristics, to handle these ambiguous
situations. One of the most common of these
is so-called “frequency gambling” – choosing
the single most likely event as the diagnosis.
This approach is a two-edged sword.
Frequency gambling on expected problems can
seriously derail problem solving when the
gamble does not pay off – that is, when the
diagnosis is not correct. The anaesthetist may
then persist with solving the incorrect problem
even when the evidence is clear that the
diagnosis is incorrect - a situation termed
“fixation error” (see below).
Precompiled Responses: The initial responses
of experts to most perioperative events arise
from precompiled responses - plans for dealing
with the specific type of event - so-called
“recognition-primed decision making”.
However even optimised responses are
destined to fail when the problem is not due to
the suspected aetiology or when it does not
respond to the usual actions – one of the many
reasons why performing anaesthesia by
“cookbook” is undesirable.
Co-ordination of Activities via Supervisory
Control: During the administration of
anaesthesia, not only are there a plethora of
tasks to perform, but these tasks can
periodically generate so much mental
workload that the anaesthetist‟s ability to
respond to other events is degraded (e.g.
focusing so much on correct placement of the
endotracheal tube that worsening hypoxia is
not recognised). The key component of crisis
management in such a situation is the
anaesthetist‟s ability to modulate their own
thinking through supervisory control and
resource management. The “supervisory
controller” allocates the scarce resource of
attention during multitasking.
Action Implementation: A particular feature of
the practice of anaesthesia, unlike other
branches of medicine, is that the decision
maker does not just writes orders, but is also
directly involved in the implementation of
actions (such as administering medication).
Executing these actions requires substantial
attention and may impair the anaesthetist‟s
physical ability to perform other activities (e.g.
having to give a drug while putting in a central
venous catheter). In performing actions a
variety of errors of execution, termed slips,
may occur. These are actions that do not occur
as planned, e.g. turning the wrong switch or
making a syringe swap.
Re-evaluation: Successful dynamic problem
solving during a state of uncertainty requires
the supervisory control to initiate frequent re-
evaluation of the situation. Re-evaluation
returns the anaesthetist to the “observation”
step, but with specific assessments in mind. In
relation to the efficacy of any interventions: Is
the problem getting better, are there any new
problems, and was the initial diagnosis
correct?
Resource Management: This concept,
borrowed directly from the world of aviation,
encompasses the ability of the anaesthetist to
command and control all the resources at hand
in order to execute the anaesthetic as planned
and to respond to problems that arise. This is
the ability to translate the knowledge of what
needs to be done into effective team activity in
the complex and ill-structured real world of the
operating theatre.
Human Performance Issues
5
Generic Principles for Prevention & Management of Difficult Clinical Situations
The decisions and actions taken by
anaesthetists can contribute to the outcome of
the patient's surgery. Even for elective surgery
in ASA I patients, there is an ever-present
(albeit small) risk of catastrophe. Death, brain
damage, or other permanent injury is the end-
results of many pathways that can begin with
fairly innocuous triggering events. Each
intervention, even if appropriate, is associated
with side effects, some of which have the
potential to be catastrophic. Furthermore,
many risks cannot be avoided. Although the
old adage still holds true (it is easier to stay
out of trouble than to get out of trouble), even
the most skilled anaesthetist can find their
talents challenged in the operating theatre
today. All over the world, improved
anaesthesia care has meant that sicker patients
present for surgery - yet when problems occur,
our actions can come under intense scrutiny.
Expectations are very high among our patients
and surgical colleagues.
A crisis is "a time of great danger or trouble
whose outcome decides whether possible bad
consequences will follow” (Gaba). Notice that
in this definition, blame is not placed for the
development of a crisis. There are so many
factors that impact on the management of a
patient that are beyond the anaesthetist‟s
control that there does not have to be an error
made for a crisis to occur. However,
understanding more about the ways in which
crises develop may help us to prevent/avoid
these events, and prevention/avoidance of such
events is implicit in the principles of crisis
management.
For our purposes a crisis or "the time of great
danger" is typically a brief, intense event or
sequence of events that offer a clear danger to
the patient requiring an active response to
ameliorate patient injury. A crisis is often
perceived as being sudden in onset and rapid in
development but at least in retrospect one can
often identify an evolution of the crisis from
underlying triggering events. Indeed the
combination of the complexity and the
dynamism of the environment make crises
more likely to occur in fields such as
anaesthesia (and intensive care and emergency
medicine). But the skills required to manage
the entire situation of the crisis have not
received a great deal of attention in the formal
training of anaesthetists until recent times. To
safeguard the patient, the anaesthetist must
manage the entire situation of the crisis,
including the environment, the equipment, and
the patient care team consisting of the surgeon,
anaesthetist, nurses and technicians. Skilled
crisis management requires that the
anaesthetist, while under stress and time
pressure, optimally implements standard
techniques of diagnosis and treatment.
Medical knowledge and skills, while essential
components, are not enough.
Gaba’s Seven “Key Points” for Preventing & Managing Critical Events
Several basic principles may help manage a
crisis more effectively, especially as humans
aren‟t very good at decision-making under
pressure.
1. Know, Modify & Optimise Your Environment
Establish the location and procedures for using
emergency equipment and supplies. Is the
layout of your (potentially new) work
environment conducive to optimal
management of a current, or potential,
emergency situation? If not, can the layout be
changed (including the position of the
anaesthetic machine and drug cart in relation to
the OR table)?
2. Anticipate & Plan
The best way to avoid a crisis is to not have
one. Failure to prepare for a
situation/procedure is one of the most frequent
contributions to errors and mishaps. Be sure
you have accumulated sufficient information
about the patient, procedure, equipment and
drugs. Do you know how to access emergency
supplies and other resources? The best use of
resources requires advance planning.
Appropriate plans come in three forms:
-Global plans for resource mobilisation in a
specific work environment.
-Specific plans for dealing with particular
problems of a specific situation (see
Runciman et al‟s crisis management
Human Performance Issues
6
algorithms 4).
-Generalised emergency procedures for the
management of critical incidents.
While it may be unstated, specific backup
procedures and contingency plans should be
formulated, in case the original plans fail. In
other words, plan for the worst-case scenario.
3. Ensure Leadership and Role Clarity
Someone has to manage the overall operating
room team. In most emergency situations that
should be the anaesthetist. Make sure that this
does occur, and that leadership is clear to the
other members of the team.
What does it mean to be a Leader? Firstly it is a matter of recognising that there
needs to be a leader and declaring who IS to be
the leader! Then it is primarily a matter of
directing and coordinating the team tasks, i.e.
deciding what needs to be done, prioritising
the necessary tasks, and assigning them to
specific individuals. The anaesthetist in charge
of the situation must have good technical
knowledge and skills and must remain calm
and organised. This command authority is
vital to maintaining control of the situation, but
control should be accomplished with full
participation of the team. The leader should be
the clearinghouse of information and
suggestions from other team members. Sound
leadership is aided and abetted by good
“followership”, such that other members of the
team (surgical & nursing) are able to convey
assertively information that may be vital to the
management of the situation.
4. Communicate Effectively
Let others within the team know when a
“situation” is developing. Give clear specific
instructions to those you are managing. Don’t
be vague. Don’t speak into thin air. Call
people by their names, use eye contact and
gesturing to help identify people. Encourage
feedback. Encourage others to close the
communication “loop”, i.e. they need to
answer your clear communication with an
equally clear communication, signalling that
they understand your directive. An open
communication style also enables the team
members to feedback when the task is
completed, to proactively help the leader, and
offer suggestions.
5. Call for Help or a Second Opinion Early Enough
Anaesthetists have a tendency to put off calling
for help. When information seems confusing,
or you feel you are operating beyond safe or
healthy limits of your ability to assimilate data
or to physically accomplish necessary
functions, have a reasonably low threshold for
asking for assistance - it is easy to get into a
situation where it is impossible to manage all
that needs to be done. Importantly fresh help
may see things that the initial person on the
spot has missed.
Remember that help may not arrive
immediately, depending on the circumstances,
so don‟t wait too long to call.
6. Allocate Attention Wisely & Use All Available Information – Avoid Fixation Errors
Errors are possible during routine situations,
and even more likely during the management
of a critical event. A common type of error is
called a fixation error, which is an undue
persistence in failing to revise actions in the
face of readily available contradictory
information. One of the better-established (yet
often overlooked) findings in stress research is
that as stress levels increase, an individual‟s
thought processes and breadth of attention
narrow (termed “attentional” or “cognitive”
tunnelling) – so that fixation (on only one facet
of the evolving situation) is more likely. This
is an important reason for calling for help if
you are stressed – you are probably missing
something!
Figure 1. Attentional tunnelling. In a crisis or times
of stress, the tendency is to focus on one variable or
explanation to the exclusion of others (from
Endsley et al, 2003).
Human Performance Issues
7
7. Distribute the Workload & Use All Available Resources
Designate tasks to those who can best do them.
You have many resources: yourself, your
anaesthetic assistant, the surgeon, other nurses
and technical personnel, and other anaesthesia
personnel. Direct your team members
effectively. Resources such as monitors and
alarms can be optimised to help reduce
workload. Humans are poor at vigilance tasks,
and alarms are useful adjuncts to the
anaesthetist’s limited attention span.
Fixation Error
There are three main types of fixation error
that should be carefully understood:
This and only this
Persistent failure to revise a diagnosis or
plan, despite plentiful contradictory
evidence.
The available evidence is interpreted to fit
the initial assessment of the situation.
Attention is allocated to a minor aspect of
a major problem.
Everything but this
Persistent failure to commit to the
definitive treatment of a major problem. -
an extended search for information is
made without ever addressing potentially
catastrophic conditions.
Everything's OK
Persistent belief that no problem is
occurring in spite of plentiful evidence
that it is.
Abnormalities are attributed to artefacts or
transients (pulse oximeter is a classic!).
Failure to declare an emergency or accept
help when facing a major problem.
To avoid these kinds of error, use your second
opinion, frequently re-evaluate what you are
doing and maintain “situation awareness”.
That is, strive to constantly keep the “big
picture” in mind!
Situation Awareness
“Experts” seem to be able to grasp the
importance of every detail in the midst of the
mass of information presented during a crisis
(Figure 2). They seem to have “eyes in the
back of their head” or the “right stuff” because
they are able to establish and maintain what
cognitive psychologists call “situation
awareness”.
Figure 2. Good information acquisition in a crisis.
Large volumes of information are assembled into a
picture of the situation (from Endsley et al, 2003).
Situation awareness has been defined as “the
perception of elements in the
environment…the comprehension of their
meaning and the projection of their status in
the near future (Endsley 1988) see fig 3).
Having a firm grasp of the situation as it
unfolds allows the leader to compare it to their
expectations and revise their actions
accordingly.
Figure 3. Situation awareness is the perception of elements in the environment…the comprehension
of their meaning and the projection of their status in the near future (Endsley, 1995).
Human Performance Issues
8
The concept of situation awareness has
evolved from aviation research to address the
important role that human performance plays
in adverse occurrences. Analysis of accidents
and near misses in aviation and now
anaesthesia & critical care medicine has
revealed that “blind spots” in the operator‟s
view of the “big picture” often trigger (and
contribute to) the evolution of a crisis.
During routine administration of anaesthesia,
maintenance of a high level of situation
awareness may not be all that necessary.
The relative rarity of potentially catastrophic
problems and the checks and balances built
into the system allow lapses of attention and
decision errors to occur without impact on
outcome. During an emerging crisis however,
the cost of failure to maintain situation
awareness during the periods of low workload
may become apparent. All of a sudden it
seems that many things need to be done
simultaneously and time and attention become
precious but limited resources. If these
resources are consumed, it may be impossible
to recover from a deteriorating process. Once
again, sorting out what is important and
keeping track of it at all times are hallmarks of
the expert practitioner.
One of the best ways to maintain situation
awareness during an evolving situation is to
delegate tasks as much as possible, thus
freeing yourself up to keep an eye on all of
what is happening.
Performance-Shaping Factors, Including Production Pressure
The practice of anaesthesia always requires the
presence of an attentive and skilled
practitioner. But we are all aware that some
days are better than others in relation to our
ability to perform at our peak while at work.
While it is unrealistic to expect peak
performance in association with every
anaesthetic we give, it is important to
recognise that the abilities of even highly
trained personnel can be profoundly influenced
by internal & external performance-shaping
factors. It is unclear whether the levels of
performance decrement likely to be induced in
typical (and indeed atypical) work situations
have any significant effect on patient care &
outcome.
There are several performance-shaping factors
that are potentially of sufficient magnitude to
be of concern to the anaesthetist – hence it is
worthwhile being aware of the following
issues in relation to our day-to-day work,
especially if more than one of these factors are
occurring simultaneously (e.g. illness &
fatigue).
Ultimately the responsibility rests with the
anaesthetist to ensure his/her performance
level is sufficient for the work at hand. A
major difficulty is that organisations rarely
provide mechanisms for personnel to excuse
themselves if they are temporarily impaired.
Ironically in many settings, mechanisms for
dealing with serious problems like addiction
are more established than for more common
occurrences (such as illness or fatigue).
Ambient Noise
The operating theatre is a relatively noisy work
environment, with mean sound levels higher
than in most offices – and peak levels that can
be very high. While some ambient noise is
controllable (conversation, music), there are
some sources of noise that are inevitable and
uncontrollable (surgical drills, equipment
alarms).
There is evidence that noise can adversely
affect human performance. Operating theatre
noise has been shown to interfere with speech
discrimination and psychometric tests of
mental efficiency & short-term memory of
anaesthesia trainees. The potential for noise to
interfere with the detection of audible alarms
and effective communication is of particular
concern.
Music
The use of music in the operating theatre is
widespread, with an impression that it may
relax the staff and enliven the day. It can even
build team cohesiveness - when all team
members enjoy the music! The effects of
discord in relation to the choice of music may
be more problematic, and some team members
prefer silence during surgery. There is no
simple answer to the question of the proper
role of music in the operating theatre. Optimal
patient care is the primary goal. The most
sensible approach is to allow any team
Human Performance Issues
9
member to veto the choice or volume of music
if they believe it interferes with their work, and
this is increasingly likely during periods of
high workload.
Masks
Whilst masks are useful to prevent infection
spread by droplets and splashes, they impede
observation of facial expression. Studies
observing communication where faces are not
clearly visible have determined an increased
risk of confusion. The wearing of masks
makes it even more critical that
communication is clear and directed,
especially in crises.
Reading
There are no data to determine the degree to
which reading by the anaesthetist during the
administration of anaesthesia distracts
attention, especially if restricted to low
workload periods. One positive aspect of this
practice is that it may combat boredom - a
significant distractor in its own right. It is
probably inappropriate to ban the practice
outright, but reading should not be allowed to
impair vigilance or patient safety. With that in
mind, a compensatory measure might be to set
the patient monitor alarm limits to only a very
narrow band, thereby increasing the likelihood
that any deviation would be quickly noted. Of
course it is to be expected that the anaesthetist
must abandon all incidental activities when
necessary and to have a very low threshold for
abandoning any potential distractions.
Fatigue and Sleep Loss
It is likely that chronic sleep deprivation,
circadian rhythm abnormalities and fatigue can
be blamed for some iatrogenic adverse patient
outcomes. Indeed the effect on performance of
being constantly awake for 24 hours equates to
a blood alcohol level above 0.05%. There is an
association between the occurrence of medical
incidents, performance failures, and time of
day that coincides with normal sleep.
However, due to the multifactorial nature of
adverse events, a causal link is difficult to
prove. All industries, including healthcare, are
bound by Occupational Health and Safety Law
to provide a safe working environment. This
includes fatigue management and rostering
systems that support the worker in having
ample opportunities to rest. It is also the
anaesthetist‟s responsibility to ensure they get
adequate sleep when rostered away from work
duties.
Each individual has their own sleep
requirement per 24-hour period. Lack of
adequate sleep means daytime sleepiness and
impaired performance ensue. For limited
periods, performance may appear unaffected.
However, short-term compensation may be
due to a deliberate slowing of actions to avoid
mistakes (a “speed-performance trade-off”),
and the response to new or emergency
conditions may be sub-optimal.
Even minimal levels of sleep loss (2 hours less
sleep than required) can lead to lapses in
performance, increased physiological
sleepiness and altered mood. Sleep loss is
cumulative, resulting in sleep debt. The
ONLY way to pay back a sleep debt is with
sleep! Chronic sleep debt is commonplace in
the medical culture, and research into sleep in
medical staff has been hampered by the fact
that chronic sleep debt is the norm.
Fatigue is the diminished ability to perform
work, and it is caused by excessive physical or
cognitive work. Mental fatigue is
accompanied by subjective feelings of
tiredness after periods of sustained
performance on predominantly cognitive tasks.
Mood, initiative and enthusiasm all decline as
fatigue progresses. Fatigue can also result
from disturbed circadian rhythms. Circadian
rhythms - relating to body temperature,
metabolism, hormonal secretion, and the
sleep/wake cycle - fluctuate on a 24-hour time
scale. Circadian lulls occur twice throughout
the 24-hour day - from 02:00-06:00 and 14:00-
18:00. These periods are associated with an
increased sleep tendency and decreased
performance capacity. Sleepiness & alertness
are opposite ends of a continuum, with the
most obvious effect of inadequate sleep being
daytime sleepiness. Healthy adults are
maximally alert by mid-morning.
Determinants of sleepiness include: decreased
quantity of sleep, decreased quality of sleep
(cf. sleep apnoea), disrupted circadian
rhythms, and the effects of medication,
including alcohol.
Long work hours, fatigue & sleep deprivation
result in dramatic changes in mood and
emotions. Depression, anxiety, irritability,
anger & depersonalisation occur in chronically
Human Performance Issues
10
fatigued workers. We can all relate to these
issues and need to be aware of them in our
interactions with patients and other staff.
As mentioned earlier, vigilance, “the ability to
remain alertly watchful, especially to avoid
danger”, is important to ensure the safe
passage of the patient through the
perioperative period - but it is unrealistic to
expect a human operator to maintain a state of
peak vigilance for a protracted period of time.
More important may be to learn to monitor
one‟s own vigilance levels, recognise the onset
of boredom and develop strategies to
overcome it. One strategy may be a walk
around the operating theatre every 15 or 30
minutes during a long procedure.
Microsleeps - intermittent actual sleep
episodes encroaching into periods of
wakefulness, and lasting a few seconds to a
few minutes - are the most extreme form of
decreased vigilance. They are signs of extreme
sleepiness and harbinger of sleep onset. Their
occurrence is difficult to predict. Most
individuals underestimate their level of
sleepiness, and behavioural & subjective
sleepiness can be masked by a stimulating
environment. It is possible to fall asleep for a
brief period and not be aware of it! Medical
personnel, like anyone else, are
physiologically vulnerable to degraded
alertness and unable to perceive the decrement.
Shift Work is an inevitable component of some
forms of work, especially in the health care
industry. It has been demonstrated to be
associated with higher rates of alcoholism, job
stress, emotional problems and physical
illnesses. One‟s ability to cope depends on the
interaction of:
Circadian rhythm. It is easier to adjust to
shift changes in a forward fashion (day –
evening – night).
Social factors.
Individual characteristics (such as
age, personality, level of fitness).
Exercise and diet. Night workers
often have poor diets due to a lack
of appropriate food at the
workplace, and often exercise less.
Personal safety
Workplace fatigue is not just a problem in
the workplace. Prolonged wakefulness
overnight followed by a drive home can be
dangerous – a safer approach may be to find
a quiet spot to nap prior to taking the trip.
Countermeasures
Sleep is a fundamental physiological drive that
cannot be prevented by willpower alone.
Because fatigue is such a widespread and
insidious problem it is important to determine
ways to counteract its effects. Potential
countermeasures include:
Scheduling patterns: Most rosters in
recent years have been designed to take
into account sleep requirements and
circadian rhythms. As a rule rotating
shifts should move in a forward direction
to optimize the circadian variation. Any
reasonable rostering pattern still relies on
the anaesthetist to be responsible in
obtaining the required amount of sleep
when rostered off-duty.
Education: Medical practitioners need to
become more aware of the impact of sleep
issues on work performance, mood, job
satisfaction and health. In high risk shift
patterns, monitoring of subjective scales
(and even objective tests) of fatigue are
warranted.
Sleep hygiene: Conditions and practices
that promote sufficient quantity and
quality of sleep. Examples of good sleep
hygiene conditions include a warm, dark,
quiet room with no distractions.
Rest breaks at work: Consider the role of
periodic breaks to enhance vigilance,
because attention spans are limited.
During long cases, short breaks out of the
theatre environment are helpful to “clear
one‟s mind”.
Strategic napping: Naps can decrease
sleepiness and improve performance.
Some individuals appear to benefit more
from naps than others. The ideal length
for a “power nap” is 45-60 minutes,
however restorative sleep can occur with
naps of only 15 minutes. “Sleep inertia”
is a period of grogginess and reduced
function for 15-30 minutes after
awakening and typically occurs with naps
over 1 hour of duration.
Medications: Caffeine can be used to
maintain alertness during periods of
Human Performance Issues
11
extreme sleepiness, but has side-effects
and can affect normal sleep.
Alcohol has a soporific effect but it
reduces the amount of REM sleep and is
best avoided as an aid to induce sleep.
Hypnotics should also be avoided, and
should certainly not be self-prescribed. A
short acting drug to initiate sleep may be
appropriate in some circumstances but
should not be taken regularly. Melatonin
use is of unproven benefit in shifting the
circadian cycle and is not generally
available in Australia or New Zealand.
Other Performance-shaping Factors
There are a number of other performance-
shaping factors to be wary of, though there is
not sufficient information on these matters to
provide a meaningful summary. Illness and Prescription Drug Use
The degree to which these affect the
anaesthetist‟s performance is unknown in the
general workplace. All anaesthetists should be
registered with a general practitioner and take
independent advice when necessary rather than
self-medicating.
Alcohol
There have been no studies of anaesthetist
performance under the influence of alcohol.
However there are some studies equating
fatigue and alcohol consumption (see above).
It is easy to imagine that performance would
be impaired after the ingestion of alcohol,
given the known negative effects of alcohol on
judgement, motor function and reaction time. Illicit Drug Use & Drug Addiction
About all that is known for sure is that work
performance is one of the last areas of life to
become impaired.
Hazardous Attitudes
It is important to recognise that your attitudes
can affect your performance just as strongly as
physiologic performance shaping factors.
There are five attitudes that are particularly
hazardous. 1
1 Note: Hazardous Attitudes (Reference: Aeronautical Decision
Making. Advisory Circular Number 60-22. Federal Aviation
Administration, Washington, DC, 1991)
These attitudes include:
"Don't tell me what to do.” (Anti-
authority) This guarantees repeating
mistakes!
"Do something quickly - anything.”
(Impulsivity) Acting impulsively without
giving thought to the best course of
action.
"It won't happen to me - it's just a routine
situation.” (Invulnerability) Every
situation could be an accident waiting to
happen.
“I’ll show I can do it. I can deal with it.”
(Macho) Taking chances is foolish, and
increases the risk to the patient!
“What's the use? It's out of my hands.”
(Resignation) It is never too late to try to
retrieve a situation.
Of these, “invulnerability” and “macho”
attitudes are especially hazardous for
anaesthetists - and can be compounded by
production pressures.
Production Pressure
There are internal, external, economic and
social pressures on the anaesthetist to pursue
efficiency and throughput, not safety, as the
primary priority. Examples include: Keeping
the Theatre Schedule moving speedily, with
few cancellations and minimal time between
cases; refusing to take breaks and failing to
acknowledge the impact of fatigue if the work
schedule extends into the evening. When
anaesthetists succumb to these pressures they
may be prone to skipping appropriate
preoperative evaluation & planning, and/or
proceeding with elective cases despite medical
concerns about the patient – doing things that
in retrospect they would consider unsafe.
If these pressures become internalised they can
lead to the development of hazardous
attitudes. Production pressure also leads to
haste, a precursor to the commission of unsafe
acts. In the final analysis, you must ensure that
the patient‟s benefit is the primary criterion for
your decisions. If you have been pressured to
proceed, surgeons or administrators are
unlikely to thank you if a patient suffers
because of it – and may well be disinclined to
come to your defence during litigation!
Human Performance Issues
12
Teamwork Issues: Social Psychology of the Operating Theatre
The operating theatre team has a somewhat
ambiguous “command” structure. The surgeon
and anaesthetist are jointly responsible for the
patient, with a supporting group of nursing &
technical staff. Each has a primary territory of
knowledge, skills & responsibility, but there is
considerable overlap. The particular
individual giving instructions to the rest of the
team at any given time will depend on the
circumstances. The degree to which various
members of the operating theatre team agree
on common objectives is also debatable.
While all would agree that a good outcome for
the patient is the ultimate goal, there can be
considerable disagreement on how to achieve
this, and which elements of patient care have
the highest priority at any given time.
The basic social and psychological effects of
working in a team should be kept in mind.
Team members can be considered in terms of
their tasks or goals and their interpersonal or
emotional orientation. The democratic style,
showing consideration for others, is likely to
be appropriate when things are going well. A
more autocratic style may predominate if
difficulties or emergencies occur. Depending
on the circumstances, it may be better to be
direct with one‟s communication, rather than
be polite but indirect. Problems arise if an
individual is either too demanding or fails to
assert proper leadership because of concerns
about upsetting colleagues –in crises, lower-
status team-members tend to defer to a higher-
status individual, even if that individual is
performing poorly. Role clarity between
trainee and supervisor is often not explicit
during the conduct of routine anaesthesia – this
is often compounded during a crisis, because
responsibility for different tasks is rarely
predefined. It has been demonstrated that
interpersonal and communication problems are
responsible for many inefficiencies, errors and
frustrations in psychologically and
organizationally complex environments.
Anaesthetists and surgeons that work together
on a regular basis tend to be able to sort out
problems without a lot of stress. We probably
need to place more importance on establishing
social relationships in the Operating Theatre 5,
6. Formal training in team management and
communication skills can produce substantial
improvements in human performance as well
as reducing safety-critical errors. Hence the
recent trend towards translating Crew
Resource Management training in aviation into
Crisis Resource Management training in
anaesthesia using immersive simulation.
While people‟s personalities can‟t be changed,
individual‟s attitudes are relatively malleable
to training interventions (see Flin 1 ).
Systems Approach to Patient Safety
(see Reason, 7)
Doctors are used to evaluating adverse events
in terms of decisions and actions made by
individual clinicians. However, it is
increasingly recognised that system-wide
issues are more important in the prevention of
such events.
The basic premise of a “systems approach” is
that humans are fallible and that errors are
inevitable. Errors originate not from the
perversity of human nature but as a result of
factors within the system in which we work.
When an adverse event occurs, the important
issue is not who “blundered”, but how the
system‟s “defences” failed. In fact, the term
“error” increasingly is being considered an
inappropriate way to categorise behaviours - in
that it implies blameworthiness - and should be
thought of merely as a way to identify
behaviours at the heart of a critical situation
see Runciman 8. Countermeasures are based
on the assumption that although we cannot
change the human condition, we can change
the conditions under which humans work.
Systems thinking is about two related
concepts:
Understanding why things happen
because of organisational and system-
related design, procedures, incentives &
disincentives.
Finding system solutions to problems
even if they involve errors by individuals.
An example is the patient who goes to
ICU after pulmonary aspiration caused by
reflux that was noted in pre-assessment
clinic, but not by the anaesthetist of
record – this person had to do a time-
compressed, corridor pre-operative
assessment. In discussing this case the
systems approach asks: “How can we
change the system to prevent this
Human Performance Issues
13
happening to others?” Rather than just
blaming an individual.
Key Points of Understanding & Analysis
Do not try to assign blame. Most events
involve multiple factors. Focus on
understanding what occurred and on
finding solutions for the future.
Don‟t be satisfied with the “easy”
explanations.
Concentrate on the situation as a whole,
not on individuals. Assess individual
behaviour and performance as a symptom
of underlying characteristics of the
system.
Keep asking “why” and “how” questions.
For every answer there is probably
another “why” question just around the
corner.
List deeper causes, even if they are not
easily correctable. They put events into
perspective and offer targets for long-term
change.
Look for situations that “invite” mistakes,
or that make it difficult to recover from
mistakes. In particular be alert for:
Design errors.
Lack of, or poorly developed, standard
procedures.
Reliance on memory or calculation for
critical decisions.
Areas of conflicting responsibility,
such as handover of care, or patient
transport.
Production pressure.
Don‟t be satisfied with explanations such
as “That‟s the way the system is and
there‟s nothing we can do about it”. The
system CAN be changed (though it might
be tricky and it might take a while!)
Recommendations & Solutions
Always look for ways to improve the
system, regardless of the proximate cause
of the particular error or occurrence under
review.
Look for ways that the system can make
up for the inevitable mistakes of
individuals.
Solutions to problems can include
changes in:
Training of personnel – training only
works if it is specific.
Design characteristics of equipment or
supplies.
Positioning of equipment or supplies.
Operational procedures (e.g. “Time-
out”).
Cognitive aids such as checklists.
Personnel supervision and staffing
levels.
As stated previously, many adverse events in
medicine result from actions made by persons
who know how to perform the relevant task
safely, have done so many times in the past –
and face significant personal consequences for
the error. Error is not the monopoly of an
unfortunate few, merely the “down-side of
having a brain”!
Although we cannot change the aspects of
human cognition that cause us to err, we can
design systems that reduce error and make
them safer for patients.
Summary
Each element of both successful and
unsuccessful management of difficult
situations has its roots not in the peculiar
strengths/weaknesses of the individual
practitioner, but rather in the intrinsic nature of
the psychology of dynamic decision making
under time pressure and stress. An important
step in improving patient care is the careful
evaluation of the various aspects of human
performance that can be improved by changes
in training of anaesthetists, by continued
education of practitioners, and by alterations in
operational systems and policies.
However, ultimately, you are responsible for
giving the best possible care to your patients.
Although perfect performance is unachievable,
you should strive to approach it. You must
also realise that the real world in which you
work may make it difficult to translate your
skills into optimal patient care. Experience
alone will not guarantee good performance,
nor can it make you immune to the types of
errors that plague all humans in complex,
dynamic domains. Production pressures,
distractions and the complexity of cases will
challenge your best intentions. An important
beginning is to recognise that crises will occur
in spite of, or even because of, your best
efforts! Therefore try to plan as best you can
for the potential disaster waiting to happen that
is each next case. Make explicit provisions for
failure of elements in the anaesthetic or
surgical plans. Prepare yourself to recognise
Human Performance Issues
14
and manage all the crises that you face,
regardless of how they might be triggered.
Utilise your department‟s quality assurance
program to adapt your practice as required,
based on your own experiences and those of
others. As you review cases of your own and
others, try to avoid becoming fixated solely on
the medical and technical aspects of how a
crisis was managed; consider the teamwork
aspects and the way in which the “larger
system” helped or hindered patient care. Seek
to change those aspects of the situation that
impeded optimum management.
GOOD LUCK!
Suggested Further Reading: Cooper JB, Gaba DM. No myth: anesthesia is a
model for addressing patient safety.
Anesthesiology. 2002 Dec;97(6):1335-7
Designing for Situation Awareness: An approach to
user-centred design. Endsley, M.R., Bolte, B.,
Jones, D.G. (2003) Taylor and Francis, New York
- how “cognitive engineering” can help us
understand what‟s going on in a crisis
Kohn LT, Corrigan JM, Donaldson MS. To err is
human - building a safer health system: National
Academy Press 2000.
Tepas, D.I. Paley, M.J. Popkin, S.M. “Work
Schedules and Sustained Performance.” In:
Handbook of Human Factors and Ergonomics G.
Salvendy (Ed)
– a comprehensive review of fatigue related studies
Weinger, M.B., Englund, C.E. Ergonomic and
human factors affecting the anaesthetic vigilance
and monitoring performance in the operating room
environment Anesthesiol (1990) 73:995-1021. A
review of performance modifying factors in
anaesthesia
Croskerry P, Cosby KS, Schenkel S, Wears R.
(Eds.) Patient Safety in Emergency Medicine.
2008; Philadelphia: Lippincott Williams & Wilkins.
(due for publication August, 2008) – an important
general text with the best single discussion of
diagnostic error for clinicians
Reducing error, Improving safety. British Medical
Journal. 320 (7237), 18 Mar 2000.
- the entire edition of this journal is useful
Human Error in Medicine. Bogner, M.S. (ed.) 1994.
Lawrence Erlbaum Assoc., Inc. New Jersey.
- especially Chapters 5, 11, 12, 13
Clinical Human Factors Group (UK)
www.chfg.org.uk (accessed May, 2008)
- a group founded in the UK by an airline pilot
whose wife died as a result of a difficult airway
during an emergency caesarean section – plenty of
interesting articles on error and redesigning systems
References: 1. Flin RH, O'Connor P, Crichton M. Safety at
the sharp end. Aldershot: Ashgate; 2008.
2. Gaba DM, Fish KJ, Howard SK. Crisis
Management in Anesthesiology. New York:
Churchill Livingstone; 1994.
3. Rall M, Gaba D. Chapter 83. Human
Performance and Patient Safety. In: Miller's
Anesthesia. New York: Elsevier; 2005.
4. Runciman WB, Kluger MT, Morris RW, Paix
AD, Watterson LM, Webb RK. Crisis
management during anaesthesia: the
development of an anaesthetic crisis manual.
Qual Saf Health Care 2005;14:1-12.
5. Lingard L, Espin S, Whyte S, et al.
Communication failures in the operating
room: an observational classification of
reccurent typse and effects. Qual Saf Health
Care 2004;13:330-4.
6. Lingard L. Perceptions of operating room
tension across professions: building
generalisable evidence and educational
resources. Academic Medicine 2005;80:S75-
9.
7. Reason J. Human error: models and
management. BMJ 2000;320:768-70.
8. Runciman W, Merry A, Walton M. Safety and
ethics in healthcare: a guide to getting it right.
Aldershot: Alshgate; 2007.
Cardiovascular Emergencies
15
CARDIOVASCULAR EMERGENCIES
Assoc Prof Sandy Garden2
This module aims to provide the skills and
knowledge to enable the implementation of
general and specific therapies for perioperative
cardiovascular emergencies.
Objectives To implement general and specific therapies
for perioperative cardiovascular emergencies.
Upon completion of this module it is expected
that the participant will understand how to
recognise and provide the perioperative
management of the following life threatening
cardiovascular emergencies:
Myocardial ischaemia & the acute
coronary syndromes
Cardiac arrest and post-arrest care
Peri-arrest conditions and cardiac rhythms
Emergency vascular access
Hypertensive crises
Crises with valvular heart disease
Perioperative stroke
Overview
This chapter is a non-exhaustive adjunct to the
standard texts and aims to provide a practical
guide to cardiovascular crises. The topics have
been selected because the greatest
perioperative cardiac risk [1] is carried by
patients with:
Unstable coronary syndromes
Unstable or severe angina
Recent myocardial infarction
Decompensated heart failure
Significant arrhythmias (high grade
atrioventricular block, symptomatic
ventricular arrhythmias in the presence of
underlying heart disease, supraventricular
arrhythmias with uncontrolled ventricular
rate).
Severe valvular heart disease
2 Thank to Drs Paul Dalley and Chris Horrocks for kindly
commenting on the draft version of this chapter.
The module excludes the management of
children and pregnant women, mechanical
cardiovascular support and issues related to
invasive monitoring.
The most recent recommendations by the
American Heart Association and the European
Resuscitation Council form the basis of most
of the text. It is important to be familiar with
the protocols used in the hospital in which you
practise, because there are subtle differences
between the recommendations of the
Australian and New Zealand Resuscitation
Councils.
Cardiovascular Emergencies
16
Myocardial Ischaemia & Acute Coronary Syndromes
Recommended pre-reading [2, 3].
Coronary artery disease is the leading cause of
death in adults in most western countries and
in a general medical context it is the most
common cause of life threatening arrhythmias
and cardiac arrest. In the perioperative context
the situation is complicated by the interplay
between surgical stress, haemorrhage,
coagulation and anaesthesia.
Patients at risk
The revised cardiac risk index identifies
patients without active cardiac conditions who
are at risk of perioperative cardiac death or
non-fatal myocardial infarction [1]:
Known coronary artery disease (previous
myocardial infarction, previous CABG, or
percutaneous intervention).
History of congestive heart failure or
stroke.
Peripheral vascular disease, +/- vascular
surgery.
Diabetes mellitus
Renal Impairment
Other risk factors [1, 2]:
Smoker
Hyperlipidaemia
Hypertension
Non-sinus rhythm
Family history (especially sibling)
Age>70
Age<40 and cocaine or metamphetamine
abuse
Anaemia (Hct<28%) [1]
Myocardial Oxygen Supply and Demand
In order to understand, identify and manage
high-risk situations and events, a clear
understanding of the balance between
myocardial oxygen supply and demand is
critical.
Supply Demand
Coronary blood flow
Arterial oxygen content
Wall tension 3
Heart rate
Contractility
Left ventricular myocardium is perfused
during diastole (dynamic coronary
resistance is greatest in systole).
Time available for coronary perfusion is
inversely related to heart rate.
An increase in heart rate increases demand
and reduces supply.
Perfusion pressure = aortic root diastolic
pressure minus left ventricular end-
diastolic pressure.
Ventricular wall tension is determined by
both preload (radius) and afterload
(pressure, systemic vascular resistance).
Hence a dilated heart has a greater oxygen
demand for the same generated pressure.
Myocardial ischaemia arises when
myocardial oxygen demand exceeds
supply. Anaerobic metabolism leads to
depletion of ATP, causing systolic and
diastolic dysfunction. Local accumulation
of anaerobic metabolites may be
responsible for pain and arrhythmias.
Management of Acute Myocardial Ischaemia
Identify at risk patients
Avoid and treat perioperative events that
threaten the myocardial oxygen
supply/demand relationship.
Reduced Supply Increased Demand
Reduced Coronary Blood
Flow
Tachycardia
Hypotension
Elevated LVEDP Reduced Arterial Oxygen
Content
Anaemia
Hypoxaemia
Increased Wall
Tension
Hypertension
Hypervolaemia Increased Heart
Rate
Increased
Contractility
Symptoms in the conscious patient:
Chest pain
Sweating
Reversible ECG changes and haemodynamic
perturbations may be noted in anaesthetized
patients:
3
Wall Tension
Pressure Radius
2 Thickness
Cardiovascular Emergencies
17
ST segment changes of ≥ 1-2mm
T wave inversion
Arrhythmias
Treatment
It is important to make a clear distinction
between myocardial ischaemia that is caused
by oxygen supply/demand mismatch, and
acute coronary syndromes caused by coronary
artery thrombotic/occlusive events due to
plaque rupture, because the treatment is
different.
If myocardial ischaemia fails to respond to
therapy, it is important to consider the
possibility of myocardial infarction.
Reperfusion therapy is the standard of care for
myocardial infarction in non-surgical patients,
but is hazardous peri-operatively because of
the concomitant anticoagulation and anti-
platelet therapy. In this situation, early
discussion with a cardiologist and the surgeon
is thus needed to determine treatment and
because of the need to consider aborting
surgery.
Treatment of acute myocardial ischaemia
should be tailored to severity of problem:
Treat precipitating events and deepen
anaesthesia if appropriate.
Consider aspirin +/- heparin if acute
coronary syndrome is suspected.
Consider invasive monitoring and
postoperative placement in a high
dependency environment.
Provide analgesia for chest pain with
morphine in awake patients.
Reduce myocardial oxygen demand and
increase myocardial oxygen supply:
Reduce heart rate (cardioselective
beta-blocker such esmolol, unless
contraindicated by heart failure,
cardiogenic shock, conduction block,
reactive airways disease). Consider
verapamil or diltiazem if asthmatic; or
if cocaine induced ischaemia [2].
Normalise blood pressure and ensure
adequate coronary perfusion pressure.
Aggressively manage hypotension or
evidence of end-organ hypoperfusion
[2]. Consider the use of a vasopressor
or inotrope.
Reduce myocardial wall tension –
nitrates. Consider afterload reduction.
Note that nitrates are contraindicated if
phosphodiesterase inhibitors such as
sildenafil (Viagra) taken in previous 24
hours (longer for some analogs).
Ensure SpO2 >90% [2], avoid anaemia.
Ensure normothermia and avoid
shivering.
Consider intra-aortic balloon pump in
refractory cases [2].
Esmolol
1 cardioselective when infusion rate
<300mcg/kg/min. If infusion rate is
higher, effect is non-selective.
Target Heart Rate = 50-60 [2].
Loading dose 250-500 mcg/kg over 1
minute, then infusion.
Infusion dose 25-50 mcg/kg/min
increasing by 25-50 mcg/kg/min every 5-
10 min.
9 minute half-life (metabolised by red cell
esterase) hence contraindications can be
viewed as relative.
Contraindications to acute -blockade are
bradycardia, AV-block, obstructive airway
disease, cardiac failure, hypotension,
haemodynamic instability, cocaine induced
coronary vasospasm [2]. Nitrates
Predominant action is a reduction in
preload (wall tension) due to venodilation,
thus reducing myocardial oxygen demand.
Avoid in RV infarction because marked
hypotension can arise due to the effect of
venodilation on RV preload.
Sublingual nitroglycerine 0.3 mg.
IV nitroglycerine 10 mcg per minute via
continuous infusion, increasing by 10 mcg
per minute every 3-5 minutes, until
response (reduction in symptoms or onset
of hypotension) [2].
Systolic BP should not be titrated below
110 mm Hg if previously normotensive, or
reduced by more than 25% if hypertensive
[2].
Platelet Inhibitors and anti-coagulants
In the perioperative context the use of anti-
platelet and anti-coagulant medication requires
careful risk-benefit analysis because of the risk
of bleeding. Consider proton pump inhibitor if
concomitant history of G/I bleeding.
Aspirin
Aspirin 160-325 mg, chewed non-enteric
formulation for rapid buccal absorption. A
lower dose of Aspirin (75-160 mg) is
Cardiovascular Emergencies
18
acceptable if the risk of bleeding is high
[2].
Contraindications: allergy (esp. if asthma),
active bleeding (gut, retina), bleeding
disorder.
Thienopyridine ADP Receptor
antagoninsts (e.g. clopidogrel) Should be considered especially in patients
intolerant of aspirin [2]. Additive effect with
aspirin.
Glycoprotein IIb/IIIa inhibitor (e.g.
Abciximab) Interfere with final common pathway for
platelet aggregation, but of questionable
benefit in the absence of revascularization.
Increased risk of major bleeding [2].
Anticoagulants Low molecular weight heparin (e.g.
enoxaparin) or unfractionated heparin should
be considered, noting that unfractionated
heparin is more readily reversed in the event of
haemorrhage.
The Acute Coronary Syndromes [2]
A dynamic continuum including unstable
angina/non-ST segment elevation (non-Q
wave) myocardial infarction
(UA/NSTEMI), and ST segment elevation
(Q Wave) myocardial infarction. Unstable
angina/NSTEMI is defined by ST-
depression or prominent T-wave inversion,
and or positive biomarkers for tissue
necrosis without ST-elevation, and in the
appropriate clinical setting (such as chest
pain), whereas unstable angina causes no
increase in biomarkers of myocardial
injury.
Typically caused by a reduced coronary
perfusion that is secondary to rupture of an
atherosclerotic plaque in an epicardial
artery. This causes platelet aggregation,
thrombus formation and non-occlusive
narrowing of the coronary artery. The
rupture of the plaque exposes
subendothelial collagen and tissue factor,
thus enabling platelet aggregation.
Other causes include re-stenosis at site of
angioplasty or stent, and less common
causes include vasculitis, embolus, trauma,
coronary artery spasm (e.g. cocaine or
methamphetamine induced), aortic
dissection, increased blood viscosity and
increase in oxygen demand.
Unstable angina typically presents as rest
angina, new-onset angina (<2 months) or
increasing angina.
The hyperdynamic circulatory state seen in
the perioperative period (secondary to
tachycardia, fever, anaemia) may
predispose to plaque rupture and also
increases myocardial oxygen demand, and
the postoperative hypercoagulable state
predisposes to thrombosis.
These syndromes are associated with an
increase in the risk of myocardial
infarction and death [2]. Patients require
monitored care in an environment where
facilities and staff for cardioversion or
defibrillation are immediately available.
The most urgent priority is determining
need for immediate reperfusion therapy
and exclusion of other potentially lethal
conditions such as aortic dissection.
Myocardial ischaemia that does not respond to
therapy should be re-evaluated and early
cardiological referral is needed. The decision
to undertake reperfusion therapy is based
largely on the 12 lead ECG and the
biochemical markers of myocardial cellular
damage (Troponin T or I, CK-MB). If there is
ST segment elevation that is unresponsive to
treatment and/or elevation of biochemical
markers, then reperfusion should be
considered. The biochemical markers may be
normal during the first 6 hours after
myocardial infarction.
Risk of Death or Non-fatal Myocardial
Infarction in Unstable Angina
Escalation of symptoms in previous 48
hours
Pain >20 minutes, rest pain
Clinical evidence of heart failure
Age >75 years
Angina at rest with ST changes > 0.5 mm
New bundle branch block
Sustained ventricular tachycardia
Troponin T or I > 0.1ng per ml
Hypotension
Renal impairment
Risk of Death Due to Myocardial Infarction
Short-term risk of lethal ventricular
fibrillation (VF) is maximal in the first 4
hours.
Cardiovascular Emergencies
19
Long term risks related to the infarct size
and location.
Early diagnosis and reperfusion result in a
reduction in infarct size, a reduction in
mortality and an improvement in long term
ventricular function [3]. Reperfusion
therapy involves either thrombolysis,
percutaneous intervention (PCI) i.e.
angioplasty with or without a stent, or
Coronary Artery Bypass Grafting.
Thrombolysis is contraindicated after
recent surgery because of the risk of
bleeding and PCI may be the preferred
option, however the need for
anticoagulation and antiplatelet therapy
renders this choice unattractive. Acute
fibrinolysis is of no benefit in the absence
of ST elevation (actually increases the risk
of myocardial infarction), unless there is
true posterior myocardial infarction, or
presumed new Left Bundle Branch Block
[2].
ST-segment elevation (≥1mm in 2
continuous ECG leads) is a key
indicator for urgent reperfusion [2].
Time from onset of symptoms to
reperfusion is critical. Maximal benefit
occurs when reperfusion is achieved
within 3 hours of occlusion, and current
recommendation is re-perfusion (PCI or
fibrinolysis) within 90 minutes of first
medical contact [3].
If reperfusion is not undertaken there is
benefit in treating the acute coronary
syndromes with both aspirin and beta-
blockers. They both reduce the risk of
myocardial infarction and the risk of death
after myocardial infarction. Beta-blockers
along with nitrates are first line therapy in
angina whereas aspirin has no effect on
angina.
Diagnosis of Acute Coronary Syndrome due to Coronary Artery Disease
Typical chest pain unresponsive to nitrates.
Transient mitral regurgitant murmur,
hypotension, sweating, pulmonary
oedema.
Twelve Lead ECG changes.
ST segment deviation of ≥0.5mm, or
symmetrical precordial T wave inversion
≥2mm while symptomatic [2].
New onset Left Bundle Branch Block.
Posterior infarction (ST depression in V1-
V4).
Biochemical markers – may be normal
during first 6 hours.
“Silent” ischaemia more likely in the
elderly, in women, those with diabetes or
prior heart failure.
Isolated Q in lead III may be normal,
especially in the absence of repolarization
abnormality in inferior leads.
Event Management
Declare a crisis – notify the surgeon.
Optimise haemodynamics.
Aspirin and beta-blockers should be
started early in the absence of
contraindications.
Urgent consultation with cardiologist, to
determine possibility of reperfusion.
Differential Diagnoses of Acute Chest Pain or
CVS Collapse
Aortic Dissection
Cardiac tamponade
Pulmonary embolus
Pneumothorax (Tension)
Oesophageal spasm or rupture
Pericarditis
Pneumonia
Cholecystitis
Summary
Patients with reversible ST segment changes or
T-wave inversion should be treated as angina.
Those with non-reversible ST-segment
elevation on the 12-lead ECG should be
investigated for possible myocardial infarction
and evaluated for reperfusion as soon as
feasible (this will usually be after the
operation). Patients who have perioperative
myocardial ischaemia have higher risk of death
in the subsequent 12 months and so need
ongoing cardiological follow-up.
Cardiac Arrest & Post-Arrest Care
Objectives
Participants must be able to recognise cardiac
arrest, be able to implement the Universal
Advanced Cardiac Life Support (ACLS)
algorithm and provide post-arrest care.
Cardiovascular Emergencies
20
Introduction
In 2005, evidence-based changes to the CPR
algorithms were accepted by international
consensus. Participants should read a
summary of these changes [4, 5]. The
likelihood of survival and the subsequent
quality of life after cardiac arrest are
determined by the time taken to restore tissue
oxygen delivery with a spontaneous cardiac
output. The most recent scientific evidence
places increased emphasis on the need for
high quality and uninterrupted chest
compressions during CPR [4, 5]. This is
because effective CPR is required to provide
oxygen and metabolic substrates to the
myocardium, and this increases the likelihood
of restoration of spontaneous circulation.
During the first few minutes of a VF cardiac
arrest, chest compressions are more important
than ventilation. Less ventilation is required
because pulmonary blood flow is reduced.
Survival after collapse decreases by 7-10% per
minute in the absence of bystander CPR, but is
2-3 times better with bystander CPR [6].
During prolonged resuscitation, and during
resuscitation for asphyxia (typical cause in
children), ventilation should be combined with
ventilation. At best, external cardiac massage
provides around 30% of normal coronary and
cerebral blood flow [7], and it is a temporising
measure used while spontaneous circulation is
restored. Vasoconstriction may improve
coronary and cerebral perfusion pressure
during CPR [8].
Three interventions are unequivocally effective
in adult cardiac resuscitation –
Cardiopulmonary Resuscitation (CPR),
defibrillation for VF/VT and
oxygenation/ventilation.
There are important differences between
perioperative cardiac arrest, unmonitored
in-hospital cardiac arrest and out-of-
hospital cardiac arrest.
Perioperative cardiac arrest
This is usually attributed to a specific cause
which must be remedied for resuscitation to
be successful. Hence it is important to search
for the cause while administering supportive
treatment. It can be difficult to decide when to
start chest compressions in a monitored
hypotensive patient. In the AIMS data the
most common rhythm in perioperative cardiac
arrest was bradycardia or asystole.
The increased availability of ultrasound in
intensive care environments means that in the
future, transthoracic ultrasound may become
the standard of care for the diagnosis of non-
arrhythmic cardiac arrest [9].
The common causes are:
Pre-existing cardiac, respiratory or renal
disease.
Drug-induced problems such as overdose,
suxamethonium induced bradycardia, and
anaphylaxis caused by any of the chemicals
to which the patient is exposed (drugs,
chlorhexidine, latex, etc).
Error or fault with the anaesthetic technique
such as problems with ventilation and
oxygenation.
Problems with the surgical technique (e.g.
vagal stimulation, carbon dioxide
insufflation or insertion of femoral
prosthesis).
Haemorrhage and hypovolaemia
Sepsis
Embolic phenomena (thrombi, fat, air)
Unmonitored in-hospital cardiac arrest
This is usually caused by unrecognized or
inadequately treated progressive physiological
deterioration with hypoxia and hypotension.
Like perioperative cardiac arrest, the cause
must be remedied for resuscitation to be
successful, and it is thus important to search
for the cause while administering supportive
treatment [7].
Out-of-hospital cardiac arrest
This is usually attributed (82% of cases) to
VF/VT secondary to heart disease and the
treatment is early defibrillation [10]. The
likelihood of successful defibrillation falls
rapidly with time and the universal advanced
cardiac life support algorithm (ACLS) places
great emphasis on early defibrillation before
the rhythm deteriorates to a non-viable rhythm
[6]. Drugs are seen very much as adjuncts to
defibrillation. The main role of adrenaline is
as an alpha agonist to increase coronary and
cerebral perfusion pressures. Meta-analysis of
randomised controlled trials comparing
adrenaline and vasopressin, showed no
difference. Adrenaline remains the drug of
choice [7].
Cardiovascular Emergencies
21
Recognition of Cardiac Arrest
In the anaesthetized patient, cardiac arrest is
usually first indicated by the physiological
monitors. This should be confirmed by
clinical examination [11]. In non-
anaesthetised and unmonitored patients,
cardiopulmonary resuscitation is recommended
if the patient is unconscious, not moving and
not breathing. Checking the carotid pulse is an
inaccurate method by which to confirm the
presence or absence of circulation [10, 12].
Management of Perioperative Cardiac Arrest [11]
Declare a crisis Notify the surgeon/stop surgery and pack
wound.
Call for help and a defibrillator.
Place patient supine and expose the chest.
Discontinue anaesthetic agents (infusions
and vaporisers).
Administer 100% oxygen and verify gas
composition.
Institute CPR (Basic Life Support) “Push
hard, push fast, allow full chest recoil,
minimize interruptions in compressions,
and defibrillate promptly when
appropriate” [4].
Undertake rapid and complete systematic
assessment of the patient, the equipment
and drugs, even if the cause is thought to
be identified.
Common errors are failure to
discontinue anaesthetic agents and
failure to administer 100 % oxygen -
check these when you go to help
someone else manage a crisis.
Universal ACLS Algorithm
See Figure 1.
The Universal ACLS Algorithm as approved
by the International Liaison Committee on
Resuscitation (ILCOR) [7] has only two
possible treatment pathways based upon the
cardiac rhythm. One path is for patients with shockable
rhythms (Ventricular Fibrillation (VF) or
pulseless Ventricular Tachycardia (VT)), and
the other path is for patients with non-
shockable rhythms (Pulseless Electrical
Activity (PEA) or Asystole). The remainder of
the algorithm is identical: chest compression,
airway management and ventilation with a
compression to ventilation ration of 30:2, i.e.
30 compressions followed by two breaths (compression rate 100/min, 10 breaths per
minute after intubation) [7], venous access and
the administration of adrenaline every 3-5
minutes, the identification and treatment of
reversible factors.
VF/VT requires immediate defibrillation.
PEA/Asystole requires immediate
thought about causes of cardiac arrest.
This is the usual path during anaesthesia.
Therapy requires clinical judgment in each
situation and the algorithm is only a guide to
therapy. The need to exercise judgment is
critical in the perioperative context because the
cause of cardiac arrest is likely to include
reversible factors.
It is important to be familiar with the protocols
used in the hospital in which you practise
because there are subtle differences between
the recommendations of the Australian and
New Zealand Resuscitation Councils.
Leader delegates areas of responsibility
In perioperative cardiac arrest there are several
skilled individuals in the room or vicinity, and
so single or two-person CPR is uncommon.
We suggest delegation of the following areas
of responsibility:
Airway/intubation/ventilation
Chest compression - change person doing
compressions every 2 minutes [7]. If
perfusing rhythm is restored this person
can keep a finger on femoral pulse.
Monitor and defibrillation
IV access and drugs
Search for cause i.e. exclude H‟s and
T‟s.
Hunt for Ventricular Fibrillation or Ventricular Tachycardia
In out-of hospital cardiac arrest, the most
common rhythm at the time of arrest is VF,
preceded by either VT or SVT [7], and
immediate defibrillation should be undertaken
with the following caveats:
Interruptions to external cardiac massage
should be minimized.
CPR should be resumed immediately
after each shock, and should continue for
2 minutes before rhythm or pulse are
assessed. After successful defibrillation the
restoration of effective cardiac output
Cardiovascular Emergencies
22
typically takes a few minutes, and CPR
should be continued during this time.
The earlier recommendation of three
“stacked” shocks no longer applies. This
change is based on efforts to reduce
interruptions to chest compression, and
evidence that modern biphasic defibrillators
have a 90% first shock efficacy.
If the delay between collapse and CPR is
>5 minutes, then 2 minutes of CPR should
precede defibrillation. This increases the
likelihood of restoring a perfusing rhythm
after shock delivery [6, 7].
Risks to healthcare workers are shock, and
spark fire in oxygen enriched environment.
Do not charge defibrillator until after
“all clear” command. Modern
defibrillators take less than 5 seconds to
fully charge.
Biphasic defibrillator first shock 120-
200J, based on the manufacturers
recommendations. If the manufacturers
recommendation is unknown, then use 200J
[6]. Monophasic first shock 360J.
Precordial thump may be of use in first 10
seconds after witnessed VF onset.
Drugs are adjuncts to defibrillation. There
is no evidence of efficacy of drug therapy
in improving long-term survival. The new
recommendations deemphasize the role of
drug administration and reemphasize basic
life support [4]. Adrenaline 1mg every
three to five minutes.
If a perfusing rhythm is transiently
restored, but cannot be maintained
(recurrent VT/VF), consider early
administration of antiarrhythmic
medication.
For children, 4J/kg, irrespective of energy
waveform [6].
If the initial rhythm is not VF/VT, then
immediately search for a cause … do not
assume a myocardial ischaemic aetiology.
The recent increase in availability of
ultrasound in intensive care environments
means that in the future, transthoracic
ultrasound may become the standard of care
for the diagnosis of non-arrhythmic cardiac
arrest [9].
Search for cause (memorize 4 H’s and 4 T’s)
Hypovolaemia (the most common cause)
Hypoxaemia
Hypo/or/hyperkalaemia;
hypomagnesaemia; hypercalcaemia
Hypo/or/hyperthermia
Tension pneumothorax
Tamponade (trauma, renal failure, thoracic
malignancy)
Thromboembolus/ pulmonary embolus
Toxicity (including anaphylaxis and
overdoses – tricyclics, -blockers, Ca++
channel blockers)
Echocardiography can be considered in the
presence of life-threatening cardiovascular
instability where the diagnosis is unclear or the
response to initial therapy is inadequate.
Pulseless Electrical Activity (PEA) and
Asytole [7, 8]
Although PEA and Asystole are grouped
together in terms of their causes and treatment,
this can be somewhat misleading because of
important differences in outcome.
PEA is cardiac electrical activity in the
absence of palpable pulse. There are often
weak contractions that can be detected with
invasive monitoring or echocardiography. It is
often caused by reversible conditions that must
be sought and treated. If the initial rhythm is
PEA then there is a far greater chance that
there is a treatable underlying cause for the
cardiac arrest.
There is a heterogeneous group of rhythms
Rapid attention to differential diagnosis
Treatment is CPR and adrenaline
Asystole:
Survival rate from a cardiac arrest with
asystole is dismal [8]. Resuscitation is
dependent upon identifying and treating the
cause.
Treatment is adrenaline and atropine (3mg
as a single bolus).
Rapid attention to differential diagnosis.
Pacing for asystole does not improve
outcome except:
- In complete heart block, so examine
ECG carefully for presence of P waves
[7].
- After cardiac surgery where pacing may
be effective [13].
Defibrillation for asystole or fine VF
increases myocardial injury and is not
recommended [7].:
Cardiovascular Emergencies
23
Figure 1. Universal Advanced Cardiac Life Support Algorithm [7]. NB. It is important to be familiar with the
protocols used in the hospital in which you practise. There are subtle differences between the recommendations
of the Australian and New Zealand Resuscitation
Councils.
Cardiovascular Emergencies
24
Post Resuscitation Care and Peri-arrest Conditions [7, 14]
The immediate goals of post-resuscitation care
are to:
Optimise cardiopulmonary function and
systemic perfusion, especially to the
brain.
Identify precipitating causes.
Institute measures to prevent recurrence.
Institute measures that may improve long-
term, neurologically intact survival.
Global Review
Repeated re-evaluation should be undertaken.
Hypoxia, hypercarbia and hypotension all
increase the risk of further cardiac arrest, and
contribute to secondary brain injury. Post-
arrest patients will frequently have
haemodynamic instability with:
Bradycardia or tachycardia.
Myocardial depression/stunning with
systolic and diastolic dysfunction.
Cerebral dysfunction and loss of cerebral
autoregulation. This will result in pressure
dependent cerebral blood flow, and so
hypotension should be aggressively treated.
Seizures occur in 5-15%.
Patients may sustain fractured ribs and
pneumothorax from compressions.
These are the leading causes of post-
resuscitation mortality and should be treated
aggressively. ABCD problems are a common
cause of post-resuscitation hypotension and
arrhythmia.
Secondary Survey
Airway Ventilation R=L
Breathing SpO2, paralyse, sedate
Circulation IV access, monitoring (vital
signs, urine output, invasive
monitoring). Verify
placement of all catheters
and cannulae
Diagnose Cause 12 lead ECG, electrolytes,
& Complications
(Na+,K
+,Ca
++,Mg
++,blo
od gases), drug screen,
glucose
CXR (#ribs, pneumothorax,
tracheal tube), consider
tamponade.
The severity of myocardial dysfunction in the
post-resuscitation period is related to the
duration of global myocardial ischaemia.
Inotropes or vasopressors may be needed to
treat the hypotension from systolic
dysfunction. Volume loading may be needed
to optimise preload in context of impaired
diastolic relaxation.
The patient may be hypoxaemic secondary to
gross V/Q mismatching and should be
ventilated with 100% oxygen until the
oxygenation is stable.
Early neurologic assessment is an unreliable
indicator of ultimate recovery of cerebral
function, assessment at 72 hours is more
reliable. Up to 20% of initially comatose
survivors of cardiac arrest may have good 1-
year neurologic outcome [14].
Hyperventilation may worsen neurologic
outcome, and normocarbia is recommended.
Mild induced hypothermia (32°-34°C)
improves neurologic outcome among initially
comatose survivors, but its practical
application may be difficult. Patients should
not be rewarmed from mild spontaneous
hypothermia (>33°C), and hyperthermia
should be avoided because it increases cerebral
metabolic rate and is associated with a worse
neurologic outcome [14].
Tight glycaemic control is recommended.
Hypotension
The specific causes must be sought and
treated. The causes of hypotension and cardiac
arrest during anaesthesia are different from and
additional to causes in other settings. In the
AIMS study the most common causes of
hypotension were drugs, regional anesthesia
and hypovolaemia. There may be more than
one cause for example, hypovolaemia and
neuraxial blockade [15].
Supportive therapy:
Volume administration
Inotropic support
Cardiovascular Emergencies
25
Life Threatening Cardiac Rhythms [7]
See figure 2. The aim of this section is to
provide an initial approach to the patient who
has a life-threatening cardiac arrhythmia. The
management of patients with cardiac
arrhythmias is driven by clinical assessment
and the need to make timely decisions:
Is the situation immediately life
threatening?
Does the patient need CPR?
Is the rhythm slow or fast?
Table 1. Simplified Approach to Dysrhythmias
If the patient is unstable with serious signs or
symptoms, then urgent and invasive therapy is
indicated. Serious signs and symptoms include
hypotension (SBP<90 in a conscious patient, a
lower pressure is usually tolerated in
anaesthetised patients), heart rate >150 or <40,
reduced level of consciousness, chest pain,
congestive heart failure.
Most perioperative arrhythmias are caused by
remedial non-cardiac causes such as infection,
hypotension, medications, metabolic
derangements and hypoxia [1]. These should
be sought and treated. Patients with serious
arrhythmias should have IV access and oxygen
therapy. Preoperative evaluation of a patient‟s
ECG may identify predisposing features.
Mechanisms of Cardiac Arrhythmia
Disorders of impulse generation -
increased or decreased.
Disorders of impulse conduction - blocked
or re-entrant.
Combinations of these.
Management of Cardiac Arrhythmias
See table 1 and Figure 2.
There are three basic questions:
What is the rhythm? There are two basic
possibilities - Bradycardia and Tachycardia.
When looking at the ECG address the
following points. Is there a P-wave, if so what
is its relationship to the QRS? Is the QRS
morphology normal, what is it width, and is
the rhythm regular?
What is the underlying
cause [16, 17]? Perioperative
arrhythmias generally
occur in patients who
have structural heart
disease and some sort of
factor that initiates the
arrhythmia.
Acute ischaemia
Sympathetic
stimulation
Drug effects
Electrolyte imbalance (especially
hypokalaemia and hypomagnesaemia [1]).
Hypoxia, hypercarbia
What is the treatment? This is determined
by the clinical urgency and the availability of
equipment (e.g. pacemaker for bradycardia).
Always address the contributory factors as
well as the arrhythmia.
Bradycardia
Bradycardia may be absolute (e.g.<40 beats per
minute) or relative (inappropriately low in the
physiological context). The treatment for
symptomatic bradycardia, irrespective of cause
[7], includes stopping vagal stimulation and
then the critical decision is whether to pace or
to use drugs.
Initial drug therapy is atropine 500mcg
repeated to a total of 3 mg. If initial
response is satisfactory, re-evaluate to
consider risk of asystole. The risk of
asystole is higher if: recent asystole, Mobitz
Urgency Rhythm Initial Therapy
Life threatening
Bradycardia Most readily available of
Electrical therapy - Pacing
Drugs
Tachycardia Electrical therapy - Cardioversion
Unstable but not immediately
life threatening
Bradycardia Reverse cause
Consider drugs
Tachycardia Reverse cause
Consider drugs
Cardiovascular Emergencies
26
II AV block, complete heart block with
wide QRS, or ventricular pauses >3
seconds.
In absence of response to atropine,
adrenaline is the recommended second line
medication [7].
Third-line drug therapies include
aminophylline, isoprenaline, dopamine,
glucagon (if β-blocker or Ca++
-blocker
overdose) and glycopyrollate.
Unstable symptomatic patients should have
transcutaneous cardiac pacing, atropine
and/or adrenaline, as a bridge to
transvenous pacemaker. Pacing should be
available for stable patients where there is a
perceived risk of asystole.
Perioperative bradyarrhythmias are usually
caused by medications, electrolyte
disturbances, hypoxaemia or ischaemia [1].
Supportive therapy should be concurrent with
identification of, and therapy for, underlying
causes.
Sinus bradycardia, First Degree Block &
Second Degree Block – Mobitz Type I
Rarely symptomatic.
All of these may be caused by excessive
vagal stimulation, especially if patient
receiving digoxin, -blocker, verapamil.
Second Degree Block has intermittent
failure of A-V Conduction. Mobitz Type I
block is generally benign and
asymptomatic. Block is usually at A-V
node, with a normal His-Purkinje System.
There is a progressive increase in delay
between P and QRS, until a QRS complex
is missed, causing an irregular QRS
rhythm.
Sick Sinus Syndrome
Alternating bradycardia and tachycardia.
Treatment – combination of
antiarrhythmics and permanent pacemaker.
Second Degree Block – Mobitz Type II
More ominous than Mobitz Type I.
Intermittent failure of AV conduction with
loss of QRS complex; without progressive
increase in delay between P and QRS.
Irregular QRS rhythm.
Usually caused by myocardial infarction or
chronic degeneration of conduction
system.
May progress unexpectedly to third degree
heart block. Symptomatic patients should
be referred to a cardiologist for permanent
pacing.
Third Degree Block
Total failure of A-V conduction. Block is
usually below A-V node and involves total
block through both bundles, hence wide
QRS. Regular QRS rhythm.
This is an unstable rhythm that is
associated with extreme bradycardia and
episodes of ventricular asystole.
Usually caused by myocardial infarction or
chronic degeneration of conduction
system.
Emergency Pacing [7, 18, 19]
Indications
Haemodynamically unstable bradycardia
(SBP<90, altered mental state, angina,
pulmonary oedema). Especially if
unresponsive to drug therapy.
Bradycardia with pause dependent
ventricular rhythm (risk of ventricular
tachycardia or ventricular fibrillation).
Cardiac arrest secondary to drug overdose,
acidosis, electrolyte disturbance or other
reversible process.
After cardiac surgery.
Relative Contraindications
Severe hypothermia (risk of triggering VF
and VF, these are also more difficult to
treat)
Brady-asystolic arrest >20 minutes (patient
is already dead).
Technique for Transcutaneous Cardiac
Pacing
This is the first choice in emergency
cardiac care.
Modern defibrillators should have
transcutaneous cardiac pacing capability.
Recommended output is more or less twice
the output of a standard peripheral nerve
stimulator and there is no significant
bystander risk (in contrast to
cardioversion/defibrillation).
Apply large diameter (8cm) stick-on
electrodes. The anterior electrode is
placed to the left of sternum at the cardiac
apex. The posterior electrode is placed
Cardiovascular Emergencies
27
immediately behind the anterior electrode,
to the left of the spine.
Initiate pacing. Default rate is typically 80
per minute. Select either fixed rate or
demand pacing. Gradually increase the
output until capture is achieved (most
transcutaneous cardiac pacing systems
have an output current of 0-200 m Amps).
Pace at 10% above capture threshold.
Check that the pacing current is
triggering the ventricle to depolarise. You should see a wide QRS complex and a
broad T wave.
Ensure mechanical capture, i.e. pulse
synchronous with ECG.
Complications of Transcutaneous Pacing
The pacemaker current has a duration of
20 - 40 milliseconds and this current may
conceal the underlying rhythm. This may
cause the operator to fail to recognise
either non-capture or underlying
ventricular fibrillation. A special
“blanking” facility that conceals the
pacemaker current must be incorporated in
the equipment.
Pain from electrical stimulation of skin or
muscle may make this difficult in the
conscious patient, hence analgesia and
sedation are required.
Tissue damage with prolonged use.
Fist Pacing
If atropine is ineffective, fist pacing may be
used while awaiting transcutaneous pacing.
Serial rhythmic blows to the lower edge of the
sternum with a closed fist.
Tachyarrhythmias [7, 17, 19]
As a rule of thumb, broad-complex tachycardia
is tolerated less well than narrow complex
tachycardia, and most wide complex
tachycardias are ventricular in origin.
Atrial fibrillation (AF) is the most
common sustained arrhythmia
encountered. Irregular rhythms are usually
atrial fibrillation. Because of the risk of
thromboembolus, patients should not be
cardioverted without prior anticoagulation
or TOE exclusion of atrial thrombi, unless
the duration of atrial fibrillation is less
than 2 days [20, 21]. In patients with no
adverse signs and duration of AF more
than 2 days, the immediate goal is rate
control, with consideration of anti-
coagulation and delayed cardioversion.
Ventricular rate control in atrial fibrillation
is most effective with beta blockers,
followed by calcium channel blockers, and
lastly digoxin [1]. Target rate is 60-80 at
rest or 90-115 with moderate exercise [20].
In patients with AF of >48 hrs (or
unknown duration) and requiring
immediate cardioversion, concurrent
anticoagulation with heparin is indicated
because of atrial hypokinesia and risk of
thrombus formation after cardioversion
[20]. This applies to synchronised DC
shock and pharmacological conversion
(flecainide or amiodarone) [22]. There is a
clustering of stroke risk at the time of
onset of AF [23].
Tachyarrhythmias are usually
differentiated on the basis of site of origin
(supraventricular or ventricular). This
distinction is important because ventricular
tachycardia may degenerate into VF,
whereas SVT is less hazardous. In
addition the pharmacological treatments
are different.
Most patients with wide-complex
tachycardia will have VT and should be
treated as such in first instance, even
though some will have SVT with Bundle
Branch Block.
Most patients with narrow-complex
tachycardia can be assumed to have
supraventricular tachycardia.
Both VT and SVT reduce the diastolic
period and thus may reduce myocardial
perfusion and precipitate myocardial
ischaemia.
A cardiology opinion should be sought,
although emergency treatment should not
be delayed.
It can be difficult to decide if the
tachycardia is due to hypotension or the
cause of hypotension.
Contributory factors should be sought and
corrected. Failure to do so reduces the
likelihood of sustained cardioversion
High circulating catecholamines.
Hypokalaemia (if K<3.6 give K at rate
of 20 mmol per hour) and then check
it.
Hypomagnesaemia (assume low if K
low, give 8 mmol (4 ml 50%) slowly
over 1-2 minutes), and repeat if
necessary.
Cardiovascular Emergencies
28
Treatment
Haemodynamically unstable patients with
sustained supraventricular or ventricular
tachyarrhythmias should be cardioverted.
The shock should be synchronised with the
R wave to minimize the risk of inducing
ventricular fibrillation.
Contributory factors should be corrected in
all patients (e.g. treat hypomagnesaemia in
torsades de pointes).
Antiarrhythmic drug therapy is indicated if
the patient is haemodynamically stable, or
has failed cardioversion; or to facilitate
rhythm stabilisation after successful
cardioversion or defibrillation.
Vagal stimuli will terminate about 25% of
episodes of paroxysmal SVT (ask patient
to blow plunger up 20 ml syringe) [7].
Synchronised Cardioversion
Cardioversion implies a synchronised shock as
opposed to the unsynchronised shock of
defibrillation.
Indications: Preferred over
antiarrhythmics if serious sign or
symptoms, HR>150, failed drug therapy.
Broad complex tachycardia and atrial
fibrillation require large energy shock:
Monophasic 200J or biphasic 120-
150J
Atrial flutter and supraventricular
tachycardia require lower energy:
Monophasic 100J or biphasic 70-120J
Pulseless VT treated as VF (asynchronous
defibrillation).
Antiarrhythmics [17]
Drug therapy is based on the proposed
mechanism of arrhythmias: Increased
automaticity, triggered activity or re-entry in
the conduction system. Every drug that is
administered unsuccessfully will add to
myocardial depression and can be
proarrhythmic (a classic example is quinidine
causing torsades de pointes).
Wide-Complex
Tachycardia
Narrow-Complex
Tachycardia
Atrial Fibrillation
First
Choice
Amiodarone Adenosine for SVT Esmolol for rate
Amiodarone or
Flecainide for rhythm
Second
Choice
Lignocaine Amiodarone Esmolol
Digoxin
Ca++-blocker,
amiodarone or
digoxin for rate
Table 2. Simplified antiarrhythmic choices
Amiodarone [7]
Effective in a broad range of supraventricular
and ventricular tachyarrhthmias. Predominant
action is Class III antiarrhythmic. Prolongs
action potential duration and the refractory
period of all cardiac cells by blocking
repolarising K+ current, thus inhibiting re-
entry. Amiodarone also blocks sodium
channels, -receptors and calcium channels.
Vasodilatation ( -blockade, Ca++
blockade,
and direct histamine release by diluent) may
cause hypotension, but cardiac output
generally preserved.
In unstable patients, if VF/VT persist after
three shocks administer 300mg amiodarone
as a bolus, a further 150 mg may be given
for recurrent or refractor VF/VT.
In stable patients, with VT or SVT,
administer 300mg amiodarone over 20-60
minutes. Additional infusions of 150 mg.
Lignocaine [7]
Class 1b antiarrhythmic. Suppresses
ventricular arrhythmias by decreasing the slope
of phase 4 depolarisation (thus reducing
automaticity) and by reducing slope of phase 0
rapid depolarisation (thus slowing conduction
through ischaemic areas). It acts preferentially
on ischaemic tissue and blocks fast sodium
channels. At the usual concentration it has no
significant effect at atrial, SA or AV node
tissue. Lignocaine causes less reduction in
myocardial contractility than amiodarone.
When used in conjunction with other
antiarrhythmic agents lignocaine may cause a
reduction in contractility and blood pressure.
Recommended for VF/VT only if
amiodarone is unavailable, should not use
both
Initial intravenous dose 1-1.5 mg per kg
Infusion 15-50 mcg per kg per minute
Magnesium [7]
8mmol magnesium is recommended for
refractory VF and VT if there is suspicion
of hypomagnesaemia, e.g. K+ losing
diuretics.
Can be given for ventricular rate control in
atrial fibrillation [7]
Also indicated for torsades de pointes and
digoxin toxicity
Bicarbonate
Only recommended if cardiac arrest associated
Cardiovascular Emergencies
29
with hyperkalaemia or tricyclic antidepressant
poisoning.
Administer 50mmol [7]
Adenosine
Acts via adenosine receptors on the cell
surface to reduce automaticity and slow
conduction at AV node. It activates potassium
channels and hyperpolarises the cells. Inhibits
adenylate cyclase and thus reduces
intracellular cAMP, leading to inhibition of
inward Ca++
and pacemaker currents. The
effect is limited to SA and AV nodes, thus
causing a reduction in SA node rate and a
decrease in AV node conduction, thus
interrupting re-entrant pathways. It has little
effect on atrial tissue, accessory pathways,
His-Purkinje or Ventricular cells (they lack the
adenosine responsive K+ channel).
Used primarily to terminate paroxysmal
supraventricular tachycardia by blocking re-
entrant pathways. Paroxysmal SVT has
different mechanisms, with 90% due to AV
nodal re-entry (60%), or AV re-entry mediated
by an accessory pathway (30%) [24].
Adenosine is indicated for both, with the
proviso that in AV re-entrant tachycardia, e.g.
Wolff-Parkinson-White syndrome conduction
across the accessory pathway may be
facilitated and may precipitate a rapid
ventricular response. In non-re-entrant
arrhythmias (e.g. a-flutter and atrial
tachycardia) adenosine may cause transient
AV block and slowing of the heart rate,
allowing the atrial rhythm to be detected
visually, thus enabling a diagnosis to be made.
Because of transient vasodilatation and
hypotension it is no longer recommended as a
method to allow VT and SVT to be
differentiated. [17].
Xanthenes competitively inhibit adenosine
receptors, therefore may need to increase the
dose of adenosine if the patient takes caffeine
or theophylline. May need less if concurrent
carbamazepine.
Adenosine has half-life of 10-15 seconds due
to rapid sequestration by red cells. This is
important because it means that it needs to be
administered as a rapid bolus and its effects are
short-lived, including side-effects (headache,
chest pain, flushing, and bronchoconstriction).
Initial rapid bolus 6mg followed by 20 ml
saline flush.
Brief asystole up to 15 seconds is
common.
If no response in 2 minutes, then
administer 12 mg.
Failure to terminate a narrow complex
tachycardia with adenosine or vagal
manoeuvres, suggests an atrial tachycardia
such as atrial flutter [7].
Esmolol
See section on myocardial ischaemia.
Verapamil
Although verapamil is very effective in narrow
complex tachycardia, it can be extremely
dangerous. For example, like adenosine, it can
increase the ventricular rate in patients with
Wolff-Parkinson-White syndrome. It is not an
early choice for most anaesthetists because it
can reduce myocardial contractility in patients
with depressed ventricular function, and can
cause gross bradycardia in patients treated with
-blockers or inhalational anaesthetics.
Cardioverter/Defibrillators [25] A defibrillator is a device that delivers a
controlled electric shock to terminate a cardiac
arrhythmia. This requires the passage of a
sufficient current through the heart to
depolarise all myocardial cells simultaneously,
with the expectation that normal electrical
activity will resume. Cardioversion is the
same principle, but with the use of a
synchronised shock applied to a rhythm other
than VF. Cardioversion requires less energy
and 100J is the most common initial energy,
except for atrial fibrillation where a larger
initial shock (200J) is recommended [20].
A variety of automated devices are now
available.
Defibrillator Features and Operation
A capacitor that stores the current
Control switches to allow charging and
discharging by the operator
Controls that allow the operator to select a
delivered energy level (Joules)
A choice between a synchronised or non-
synchronised shock. Unsynchronized
mode is usually the default setting.
Cardiovascular Emergencies
30
CurrentEnergy
R.t(R=resistance and t=time)
Modern defibrillators deliver their energy
as a biphasic waveform. They have a
greater first-shock efficacy for long
duration VF/VT than monophasic
defibrillators, and do so with lower
delivered energy. Monophasic
defibrillators although widely used are no
longer manufactured. Biphasic energy
recommendations are manufacturer-
specific. This is because the required
energy varies depending upon the specific
waveform of discharge.
Optimise transthoracic resistance
Good contact with chest wall
Appropriate size of electrode (large) and
use of conductive gel
End-expiratory timing (air in the chest
increases the impedance)
Bone is a poor conductor and should be
avoided
Electrode placement
Aim is to maximise current flow through
the heart
Anterior electrode right parasternal, below
the right clavicle
Apical electrode is midaxillary line at level
of nipple
Synchronisation
Used to avoid the risk of inducing VF.
The shock is synchronised relative to QRS,
so that the shock is delivered after the
relative refractory period
Many defibrillators re-set to the
asynchronous mode after delivering a
shock and need to be re-set to the
synchronised mode
If there is a delay in synchronisation (for
example a problem sensing the QRS
complex) then use an unsynchronised
shock
Hazards to patient
Damage to heart - choose the minimum
effective energy. Initial shock energy
reflects a compromise between probability
of success and risk of harm
The shock energy should be increased only
if a shock fails to terminate the rhythm. If
the defibrillation is effective but the
arrhythmia recurs, then the problem is
recurrence, not failure to defibrillate and so
re-shock with the same energy. Address
the underlying cause and add an
antiarrhythmic drug. Be sure to
differentiate failure to defibrillate from
rapid reversion to VF.
Electrical induction of VF may occur with
asynchronous shocks
Insufficient or wrong gel, including
metallic GTN patches can cause arcing and
burns or fire risk
Damage to implanted pacemakers or
defibrillators - try and avoid defibrillation
directly over implanted devices
Hazards to healthcare workers
Give clear warning of impending shock. Do
not charge defibrillator until after “all
clear”. Modern defibrillators require less
than 5 seconds to charge.
Procedure for Defibrillation
It is essential to be familiar with the equipment
used in your own hospital.
Defibrillation/cardioversion will be practiced
at a skill station.
Wide-Complex or
Atrial Fibrillation
Narrow-Complex or
Atrial Flutter
Biphasic 120-150 J 70-120 J
Monophasic 200 J 100 J
Table 3. Simplified first shock energy settings [6]
Cardiovascular Emergencies
31
Figure 2. Universal algorithm for tachycardia with pulse [7]. NB. It is important to be familiar with the
protocols used in the hospital in which you practise. There are subtle differences between the recommendations
of the Australian and New Zealand Resuscitation Councils.
Cardiovascular Emergencies
32
Crises with Valvular Heart Disease
Pre-reading from an authoritative book on
cardiac anaesthesia such as Chapter 20 in
Kaplan [26] is recommended.
The management of crises in patients with
valvular heart disease is significantly aided by
the correct diagnosis. In broad terms the risk
of a perioperative cardiac event is greatest with
a stenotic lesion than a regurgitant lesion, and
aortic stenosis is the most common. Diagnosis
is crucial because the therapy for stenotic
lesions may include a reduction in heart rate
and an increase in afterload, whereas the
converse is typically advocated in
regurgitation.
With aortic stenosis there is an increased
perioperative risk is myocardial ischaemia, and
with mitral valve disease there is an increased
risk of heart failure and atrial dysrrhythmias.
[1].
Aortic stenosis
Aortic stenosis is the most common valvular
heart disease in the elderly, affecting between
2 and 9 percent of adults over the age of 65
and is concomitant with coronary artery
disease in 50% of patients [27]. Severe aortic
stenosis (mean pressure gradient > 50mm Hg,
valve area < 1 cm2 or symptomatic) poses a
high risk of perioperative myocardial
infarction and symptomatic patients should be
offered valve replacement prior to elective
non-cardiac surgery [1]. Risk is also related to
the extent of left ventricular hypertrophy, the
presence or absence of left ventricular
dysfunction and the type of surgery. The rate
of complications is much higher in patients
with undiagnosed severe aortic stenosis [27].
Because of reduced ventricular compliance, a
high filling pressure is required and
maintenance of preload is desirable. Sinus
tachycardia or atrial arrhythmias can worsen
the load on the left ventricle, causing heart
failure and/or myocardial ischaemia, and β-
blockade should be considered, aiming for a
heart rate of 50-60. Hypotension may cause a
dramatic reduction in coronary perfusion and
should be treated aggressively with an α-
agonist. Patients with aortic stenosis or
hypertrophic cardiomyopathy may develop
myocardial ischaemia without having coronary
artery disease.
Aortic Regurgitation
Tachycardia useful to optimize forward flow.
A critically low diastolic pressure in the
presence of a high left ventricular diastolic
pressure may compromise coronary perfusion,
and in the event of cardiac arrest, coronary
flow will be particularly poor during CPR.
Mitral Valve Disease
Patients with symptomatic mitral stenosis or
regurgitation carry an increased risk of
perioperative congestive heart failure [1].
Mitral valve disease is associated with
pulmonary hypertension and atrial arrhythmias
(especially atrial fibrillation). Tachycardia is
poorly tolerated in severe mitral stenosis
because of limited time for atrial emptying
(and thus left atrial pressure rises further, and
left ventricular filling is compromised). In
contrast after-load reduction is helpful in
mitral regurgitation.
Hypertrophic cardiomyopathy [28]
This disease is more common than previously
recognized (1:500) and is frequently
undiagnosed. Dynamic left ventricular outflow
tract (LVOT) obstruction due to asymmetric
septal hypertrophy is particularly relevant to
perioperative care. The outflow tract
obstruction is worse with increases in
contractility, reduction in preload, or a
decrease in ventricular volume. Vasodilators
will worsen the LVOT obstruction and any
associated mitral regurgitation.
Histologic features include disorganised
cardiac muscle cell architecture (found in 95%
of patients who die of this disease, and not
confined to hypertrophic regions), reduced
density of arterioles relative to degree of
hypertrophy, myocardial fibrosis.
Symptomatic patients fall into three main
groups: progressive heart failure (+/- angina),
atrial fibrillation, or sudden death due to
arrhythmias. Paroxysmal atrial fibrillation is
poorly tolerated because of the diastolic
dysfunction and may cause acute deterioration.
For patients at high risk of sudden death, an
implanted cardioverter-defibrillator is the
current treatment of choice.
Cardiovascular Emergencies
33
These symptom patterns are the typical cause
of perioperative cardiac morbidity and
mortality, and as with valvular heart disease,
unrecognized lesions are a significant problem.
For example a patient who sustains acute
haemorrhage resulting in systemic
hypotension, will develop dynamic LV
outflow obstruction and the situation may be
aggravated by the administration of adrenaline.
Strong consideration should be made for
perioperative β-blockade.
Hypertensive Crises [29] The perioperative risk attributed to hypertension is
related to the extent of hypertension-induced
end-organ damage rather than the blood
pressure per se. However, patients who have
poorly treated severe hypertension (e.g. 180-
209/110-119) have an increased risk of
intraoperative cardiovascular lability and
perioperative myocardial ischaemia.
Therapy for perioperative hypertensive crises
should be directed at the underlying cause of
the acute hypertension and the related
morbidity. The most common causes of severe
intraoperative hypertension identified in the
first 4000 AIMS reports were the inadvertent
administration of a vasopressor (40%),
excessive surgical stimulation or light
anaesthesia (21%), and failure to deliver the
anaesthetic (14%). Other less common causes
included hypercapnoea, pre-eclampsia,
carcinoid syndrome, and phaeochromocytoma.
Serious morbidity occurred in six patients and
consisted of myocardial infarction, pulmonary
oedema and awareness [30].
Immediate treatment [31]:
Stop the surgery until control is achieved.
Exclude measurement error (repeat the
measurement, correct cuff size, ensure the
transducer has not fallen to the floor).
Treat the cause (e.g. deepen the anaesthesia
with 10-20 μg/kg alfentanil, check that the
ventilation and oxygenation are adequate,
check that this is not the response to
intracranial hypertension in head injured
patients. Consider uncommon problems
such as malignant hyperthermia or
autonomic hyper-reflexia if chronic spinal
cord injury).
Consider specific antihypertensive therapy
such as vasodilators and beta blockers.
Check that usual antihypertensives has been
administered. Caution should be exercised
if administering β-blockers without
vasodilators in this context, because of the
risk of precipitating acute left ventricular
failure.
Subsequent investigation should be considered
to exclude rare and unexpected conditions such
as thyroid storm, phaeochromocytoma, and
other endocrine causes of hypertension [31].
Perioperative Stroke [32, 33] Perioperative stroke is rare outside the context
of cardiac or vascular surgery. Emergency
neurologic consultation is required.
Nearly 2/3 of cases are embolic in origin and
treatment options are limited because systemic
Tissue Plasminogen Activator (t-PA) is likely
to be contraindicated because of the risk of
haemorrhage at the surgical site. Outside the
perioperative context, fibrinolytic therapy for
stroke results in improved outcome.
Fibrinolysis must be administered within three
hours of onset of symptoms, and so is
administered to less than 10% of stroke
patients.
Perioperative therapeutic options all require
interventional radiological procedures and
include intraarterial thrombolysis, mechanical
thrombectomy or embolectomy. All of these
require intervention within 6 hours of stroke
onset, and so rapid diagnosis and treatment are
required.
Diagnostic investigations should include a CT
scan of the brain to exclude haemorrhage; and
a 12 lead ECG to exclude atrial fibrillation or
recent myocardial infarction as sources of
embolic stroke.
Supportive measures include those directed at
reducing secondary injury, such as avoiding
hypoxaemia, hypotension, fever, and ensuring
tight glycaemic control.
Emergency Vascular Access
The traditional EMST/ATLS approach has
been to undertake two attempts at peripheral
venous cannulation, and failing that to
undertake peripheral venous cut-down. The
use of venous cut-down is now controversial
because the complication rates of cut-down are
similar to femoral vein cannulation and central
Cardiovascular Emergencies
34
vein cannulation (although the complications
here are more serious). Cut-down takes longer
to achieve, the complication rate is mostly
related to operator experience and it is
probably more appropriate to limit their use to
surgical personnel.
In trauma patients, consider caval injury, and
have IV access above or below diaphragm,
depending on site of injury. Cervical injury is
a relative contraindication to internal jugular.
With chest injury, place the central line on
same side as chest injury to avoid injury to
good lung. Poisseulle‟s law determines flow
rate. If using vascular sheath with a side arm
as a volume line, ensure that any valves are
capped, to avoid air entrainment with rapid
infusion.
It has been recommended that in any evolving
crisis, that the satisfactory placement of
existing vascular access should be questioned
[34]. Extravasated lines used with pressure
infusion systems can cause a compartment
syndrome.
Vascular Access Options
Peripheral vein
Percutaneous - procedure of choice.
Cut-down requires surgical expertise –
long saphenous, cephalic, basilic, median
cubital.
Central vein
When peripheral sites not available.
Low complication rate with experienced
personnel.
Life threatening complications include
haematoma, haemo/pneumothorax,
hydrothorax, cardiac tamponade, air
embolus, and arrhythmia.
Complication rate increases with each
needle pass and success is very unlikely
after 5 needle passes.
Consider ultrasound-guided access.
Femoral vein
Cannulation has less immediate
complications and can be undertaken
concurrently with airway management.
Intraosseous [8]
The device must be flushed before use, and
a lignocaine bolus (2ml of 2% lignocaine)
is recommended to reduce pain with
infusion.
Other than stating that resuscitation drugs
can be administered by this route, ILCOR
has not specifically stated which drugs can
be administered. In a dog model, the
Intraosseous is similar to intravenous in
terms of pharmacokinetics and dynamics
for adrenaline, sodium bicarbonate,
calcium chloride, hydroxyethyl starch,
50% dextrose in water, and lignocaine .
Can be used in all age groups. Typically
used most successfully in preschool
children (less than 6 years), because the
cortical bone is softer and intramedullary
flow rates are higher.
http://www.facs.org/trauma/publications/v
asaccess.pdf However, specific equipment
is now commercially available for use in
adults.
Intraosseous route is accepted by the
European Resuscitation Council and the
American Heart Association as an
alternative form of IV access in adults. [7,
35, 36].
When modern access devices (e.g. power
drill) are used, access is safer and faster
than central venous access, with a typical
insertion time of 10 seconds.
Pharmacokinetics are similar to central
venous access and any drug can be
administered by this route.
Can be used to draw laboratory tests.
Rapid infusion in adults is not really
feasible…similar to a 20-22 gauge IV, but
a small IV is better than no IV.
Cardiovascular Emergencies
35
References 1. Fleisher, L.A., et al., ACC/AHA 2007
guidelines on perioperative
cardiovascular evaluation and care for
noncardiac surgery. Circulation, 2007.
116(17): p. e418-99.
2. Anderson, J.L., et al., ACC/AHA 2007
guidelines for the management of patients
with unstable angina/non ST-elevation
myocardial infarction. Circulation, 2007.
116(7): p. e148-304.
3. Antman, E.M., et al., 2007 Focused
Update of the ACC/AHA 2004 Guidelines
for the Management of Patients With ST-
Elevation Myocardial Infarction.
Circulation, 2008. 117(2): p. 296-329.
4. Hazinski, M.F., et al., Major changes in
the 2005 AHA Guidelines for CPR and
ECC: reaching the tipping point for
change. Circulation, 2005. 112(24 Suppl):
p. IV206-11.
5. Morley, P., Adult Cardiopulmonary
Resuscitation in 2007, in Australasian
Anaesthesia 2007, R. Riley, Editor. 2007,
ANZCA: Melbourne. p. 9-17.
6. Deakin, C.D. and J.P. Nolan, European
Resuscitation Council guidelines for
resuscitation 2005. Section 3. Electrical
therapies: automated external
defibrillators, defibrillation, cardioversion
and pacing. Resuscitation, 2005. 67 Suppl
1: p. S25-37.
7. Nolan, J.P., et al., European Resuscitation
Council guidelines for resuscitation 2005.
Section 4. Adult advanced life support.
Resuscitation, 2005. 67 Suppl 1: p. S39-
86.
8. Association, A.H., 2005 American Heart
Association Guidelines for
Cardiopulmonary Resuscitation and
Emergency Cardiovascular Care Part 7.2:
Management of Cardiac Arrest.
Circulation, 2005. 112: p. IV-58-IV-66.
9. Hernandez, C., et al., C.A.U.S.E.: Cardiac
arrest ultra-sound exam--a better
approach to managing patients in primary
non-arrhythmogenic cardiac arrest.
Resuscitation, 2008. 76(2): p. 198-206.
10. Handley, A.J., et al., European
Resuscitation Council guidelines for
resuscitation 2005. Section 2. Adult basic
life support and use of automated external
defibrillators. Resuscitation, 2005. 67
Suppl 1: p. S7-23.
11. Runciman, W.B., et al., Crisis
management during anaesthesia: cardiac
arrest. Qual Saf Health Care, 2005. 14(3):
p. e14.
12. ILCOR, 2005 International Consensus on
Cardiopulmonary Resuscitation and
Emergency Cardiovascular Care Science
with Treatment Recommendations. Part 2:
Adult basic life support. Resuscitation,
2005. 67(2-3): p. 187-201.
13. Soar, J., et al., European Resuscitation
Council guidelines for resuscitation 2005.
Section 7. Cardiac arrest in special
circumstances. Resuscitation, 2005. 67
Suppl 1: p. S135-70.
14. Association, A.H., 2005 American Heart
Association Guidelines for
Cardiopulmonary Resuscitation and
Emergency Cardiovascular Care Part 7.5:
Postresuscitation Support. Circulation,
2005. 112(24): p. IV-84-IV-88.
15. Morris, R.W., et al., Crisis management
during anaesthesia: hypotension. Qual Saf
Health Care, 2005. 14(3): p. e11.
16. Atlee, J.L., Perioperative cardiac
dysrhythmias: diagnosis and management.
Anesthesiology, 1997. 86(6): p. 1397-424.
17. Thompson, A. and J.R. Balser,
Perioperative cardiac arrhythmias. Br J
Anaesth, 2004. 93(1): p. 86-94.
18. Association, A.H., 2005 American Heart
Association Guidelines for
Cardiopulmonary Resuscitation and
Emergency Cardiovascular Care Part 5:
Electical Therapies. Circulation, 2005.
112(24): p. IV-35-IV-46.
19. Association, A.H., 2005 American Heart
Association Guidelines for
Cardiopulmonary Resuscitation and
Emergency Cardiovascular Care Part 7.3:
Management of Symptomatic Bradycardia
and Tachycardia. Circulation, 2005.
112(24): p. IV-67-IV-77.
20. Fuster, V., et al., ACC/AHA/ESC 2006
Guidelines for the Management of Patients
with Atrial Fibrillation. Circulation, 2006.
114(7): p. e257-354.
21. Mann, C.J., S. Kendall, and G.Y. Lip,
Acute management of atrial fibrillation
with acute haemodynamic instability and
in the postoperative setting. Heart, 2007.
93(1): p. 45-7.
22. Sulke, N., F. Sayers, and G.Y. Lip,
Rhythm control and cardioversion. Heart,
2007. 93(1): p. 29-34.
23. Kalra, L. and G.Y. Lip, Antithrombotic
treatment in atrial fibrillation. Heart,
2007. 93(1): p. 39-44.
24. Delacretaz, E., Clinical practice.
Supraventricular tachycardia. N Engl J
Med, 2006. 354(10): p. 1039-51.
25. Salukhe, T.V., D. Dob, and R. Sutton,
Pacemakers and defibrillators:
anaesthetic implications. Br J Anaesth,
2004. 93(1): p. 95-104.
26. Cook, D.J., P.R. Housmans, and K.H.
Rehfeldt, Valvular Heart Disease:
Replacement and Repair, in Kaplan's
Cardiac Anesthesia, J.A. Kaplan, Editor.
2006, Elsevier Saunders: Philadelphia.
Cardiovascular Emergencies
36
27. Christ, M., et al., Preoperative and
perioperative care for patients with
suspected or established aortic stenosis
facing noncardiac surgery. Chest, 2005.
128(4): p. 2944-53.
28. Poliac, L.C., M.E. Barron, and B.J. Maron,
Hypertrophic cardiomyopathy.
Anesthesiology, 2006. 104(1): p. 183-92.
29. Howell, S.J., J.W. Sear, and P. Foex,
Hypertension, hypertensive heart disease
and perioperative cardiac risk. Br J
Anaesth, 2004. 92(4): p. 570-83.
30. Paix, A.D., et al., Crisis management
during anaesthesia: hypertension. Qual
Saf Health Care, 2005. 14(3): p. e12.
31. Allman, K.G., A.K. McIndoe, and I.H.
Wilson, eds. Emergencies in Anaesthesia.
2005, Oxford University Press: Oxford.
32. Selim, M., Perioperative stroke. N Engl J
Med, 2007. 356(7): p. 706-13.
33. Association, A.H., 2005 American Heart
Association Guidelines for
Cardiopulmonary Resuscitation and
Emergency Cardiovascular Care Part 9:
Adult Stroke. Circulation, 2005. 112(24):
p. IV-111-IV-120.
34. Singleton, R.J., et al., Crisis management
during anaesthesia: vascular access
problems. Qual Saf Health Care, 2005.
14(3): p. e20.
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Rescue access made easy. Journal of
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650-4; discussion 654-5.
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intraosseous, central intravenous, and
peripheral intravenous infusions of
emergency drugs. Am J Dis Child Volume
144, Issue 1, 1990, Pages 112-117.
Airway Emergencies
37
AIRWAY EMERGENCIES
Assoc Prof Leonie Watterson
Dr Adam Rehak
This module aims to assist you in developing:
A routine approach to your anaesthesia
practice that reduces the likelihood that you
will encounter airway difficulties.
A systematic approach to recognising and
responding effectively when difficulty with
the airway arises.
The learning outcomes are know-how regarding:
Primary, contingency and emergency
planning in airway management.
Decision-making to support best practice
in primary planning.
Contingency plans for difficult intubation,
using the Difficult Airway Society (DAS)
algorithms as an example.
Emergency plans for the obstructed
airway and compromised ventilation.
Procedural knowledge relevant to
Bedside manoeuvres to assist
intubation by direct laryngoscopy.
Intubation by indirect methods
including the intubating laryngeal
mask airway (ILMA) and alternatives
to intubation, such as ventilation via
the Proseal™ laryngeal mask airway.
The emergency surgical airway in
conjunction with an obstructed
airway.
Overview
Good practice in anaesthesia is underscored by
careful planning and preparation, early
recognition of problems and know-how regarding
effective interventions. Prior to commencing
anaesthesia the well prepared anaesthetist plans
for expected and unexpected events.
1) The primary plan is the preferred anaesthetic
technique, reflecting best practice according
to available evidence and tailored to the
patient’s needs.
2) It is also practical and worthwhile to plan for
a small number of contingencies. These
include failure of the primary plan and
complications for which there is a reasonable
index of suspicion. Contingency plans can
also be tailored to the known needs of the
patient and surgery.
3) Emergencies, which are unanticipated and
unlikely, can potentially develop during
anaesthesia. It is not practical to formulate
tailor-made plans for each of these. However,
human factors research informs us that over-
reliance upon instinctive pattern recognition
and problem solving may contribute to sub-
optimal management of these situations 1, 2, 3
.
Emergency plans are simple pre-rehearsed
algorithms and decision-support tools that
support our clinical judgment and provide
structure and logic to our management of
these events.
Airway Emergencies
38
The Primary Plan For Airway Management
Your preferred approach to a case is your
primary plan. It reflects best practice tailored
to the individual patient‟s needs, intended
surgery and operating environment. A
decision-support tool is shown in Box 1.
1. Assess your patient and situation
2. Analyse your options in terms of risks and
benefits
3. Make a provisional plan
4. Road-test this with medical and nursing
colleagues
5. Revise if necessary
Box 1: Steps in planning your anaesthetic technique
Assessing the airway
The greatest risk associated with airway
management is failure to oxygenate4. This
follows airway obstruction or inadequate gas
exchange in the presence of a patent airway.
Many anaesthetists are particularly concerned
with these occurring during induction of
anaesthesia, however these can occur under a
range of circumstances both within and remote
from the operating theatre.
The incidence of difficult intubation varies
between studies and with the definitions used.
It is commonly classified in terms of Cormack
and Lehane‟s grading of the view obtained
during direct larygoscopy5 (figure 1 (b)).
Figure 1. (a) Mallampati classification modified by
Samsoon and Young. Class I – tonsillar pillars
visualised, Class II – entire uvula visualised, Class III –
only the base of the uvula visualised, Class IV - only the
hard Palate is visualised. (b) Laryngoscopic grade
according to Cormack and Lehane. Grade 1 – the entire
glottic orifice is seen, Grade II – only the posterior aspect
of the glottic orifice is seen, Grade III – the glottic orifice
is not seen, Grade IV – the epiglottis is not seen (from
Samsoon and Young 7).
Table 1 summarizes the incidence of various
problems encountered during tracheal
intubation. It should be noted that the
definitions for difficult intubation and mask
ventilation used by the American Society of
Anaesthetist‟s Task Force on Management of
the Difficult Airway assume the operator is a
„conventionally trained anesthesiologist‟. The
incidence of these problems may be
higher for trainees6.
Table 1. Incidence of difficult intubation according to
the problem encountered (From Crosby et al6).
Assessment for difficult intubation
Prior examination of the airway assists in
predicting the view during laryngoscopy.
Mallampati and co-workers
reported a
correlation between the oropharyngeal
structures observed during mouth opening and
the degree of difficulty of laryngeal exposure
obtained at laryngoscopy. This was
subsequently modified by Samsoon and co-
workers7 (fig 1(a)). Mouth opening is now
considered to be an imprecise predictor of
difficult intubation when used alone, but
increases in sensitivity and specificity when
other markers are present6,7,8,9,10
. Further
research has identified additional predictive
signs. These are presented below.
Mallampati III-IV
Limited neck extension
Thyromental distance <6cm (figure 2)
Inability to thrust jaw forward past upper
teeth
Short neck
Prominent teeth, natural teeth in elderly
A proportion of patients with a difficult
intubation have no identified clinical
predictors. This figure is reported to be as
high as 16.3%11
. Inspection of records of
previous anaesthetics may reveal a history of
difficult intubation in some of these patients.
Problem Incidence (%)
Intubation requiring several attempts or
different blades
1-18
Intubation possible, but Cormack and
Lehane Grade IV
1-4
Intubation impossible 0.05-0.35
Intubation and ventilation impossible
leading to cerebral damage
0.0001-0.02
Airway Emergencies
39
Figure 2. The Savva and Patil measurements indicating
critical distances. The head is fully extended on the neck 9.
Assessment for airway obstruction or
inability to ventilate via bag and mask
Signs which may herald difficulty maintaining
a patent airway with a sealed face mask
include:
A short neck
A thyromental distance less than 6 cm
Excessive head and neck fat
Beards
Edentulous
Special Risk Groups
A number of conditions are associated with
difficult intubation and/or airway obstruction.
Landmarks for a surgical airway may also be
obscured in some of these conditions.
Obesity and sleep apnoea These commonly occurring conditions can be
associated with redundant pharyngeal soft
tissue which contributes to airway obstruction
when the patient is asleep or sedated. Elevation
of the tongue and soft tissues during
laryngoscopy may also be more difficult than
usual11
.
Pregnancy
Pregnant patients are reported to have an
incidence of failed intubation which is tenfold
higher than the non-pregnant population 12,13,14,15
. The larynx may be relatively anterior
due to upward transmitted pressure from the
gravid uterus. Pre-eclampsia creates additional
risks if oedema affects the airway. Pregnant
patients are at risk of pulmonary aspiration
pneumonitis as a consequence of their more
acidic gastric juices and a greater tendency to
regurgitation, compared to non-pregnant
patients.
Conditions causing bony restriction
Rheumatoid arthritis
Ankylosing spondylitis
In these conditions an otherwise normal larynx
may sit anteriorly because restricted movement
in the cervical spine or temporomandibular
joint limits the laryngoscope‟s capacity to
elevate the tongue.
Conditions associated with oedema
Angioneurotic oedema
Postoperative bleeding
Recent intubation trauma
Acute burns
Oedema may involve the tongue or laryngeal
inlet causing obstruction. At laryngoscopy, the
laryngeal structures may be within view, but
unrecognizable from the surrounding tissue
due to oedema. These patients prefer to be
nursed sitting up and may develop
symptomatic airway obstruction if laid supine
so careful evaluation of the airway in the
supine position is worthwhile. See emergency
plans for management strategies.
Conditions causing soft tissue tethering or
displacement of the larynx
Airway radiation
Airway tumours
Previous airway surgery
Retrosternal goitre
Tethering may cause the larynx to deviate from
the midline and may also limit elevation of the
tongue and pharyngeal soft tissue. Tumours
may displace or rotate the larynx, distorting its
normal appearance. Tumours may also cause
oedema and may bleed, if friable. Tumours,
retrosternal goitres and mediastinal masses
may compress the intrathoracic trachea when
the patient is laid supine or administered
muscle relaxants. This creates a high risk for a
“can‟t intubate, can‟t ventilate” situation.
Assessment of the airway in the supine
position is useful in these patients.
Airway Emergencies
40
Airway Trauma
Blunt trauma may cause oedema and bleeding
associated with facial fractures contributing to
difficulty with mask ventilation and intubation.
Penetrating injuries may cause distortion of the
normal anatomy so that visualisation of the
larynx is difficult. The anterior aspect of the
neck may be involved in the trauma which
limits the surgical airway as a fallback. The
patients should be considered to have an
unstable cervical spine, until cleared. They are
often unfasted and at risk of aspiration of
stomach contents.
Assessing other factors
The risk of preventable emergencies is
increased when other factors are not favourable 1, 2, 3
. These should be incorporated into your
decision-making. (See Figure 3).
Figure 3: Situational factors potentially contributing to
the difficult airway
1) Who is the Patient?
i) Is the patient at risk of aspiration?
ii) Does the patient have co-morbidities
or preferences relevant to choice of
anaesthetic technique?
2) What surgical factors are relevant?
i) Are there requirements for muscle
relaxation and mechanical ventilation?
ii) Will you have access to the airway?
iii) What is the expected duration of
surgery and blood loss?
iv) Does the surgeon have individual
preferences?
3) Who are you working with and what
resources do you have?
i) How experienced are the people in
your team?
ii) Do you know the layout of the
environment and location of
equipment?
4) Are the environmental conditions
favourable?
i) Will the conditions create additional
difficulties? These include: the time of
day, location and ambient conditions
(noise, lighting, access to the patient).
5) Are you competent to use this approach?
i) How experienced are you?
ii) What factors are impacting upon your
performance during this case? Are you
distracted or fatigued?
Analysing risks and benefits
Each of the factors you consider in your
assessment should be weighted according to
the magnitude of risk they pose. For instance a
patient predicted to be difficult to intubate
poses less of a risk than a patient predicted to
be impossible to oxygenate with a bag and
mask. General anaesthesia with muscle
relaxation is an acceptable technique for
elective surgery in the former situation,
assuming the patient can be easily oxygenated.
However it is not likely to be a safe technique
in the latter situation. The relative risk is offset
by other factors, listed above. For example,
the decision to awake the patient following
failed intubation for lower segment caesarean
section is influenced by the status of the foetus,
assuming the patient can be oxygenated by
mask or laryngeal mask airway.
The provisional plan
After assessment of the patient and
consideration of the risks and benefits, a
provisional primary plan is selected. This is
only a provisional plan because road-testing
the plan (see later) may alter your choice of
technique. This provisional plan may involve
any of the following techniques:-
Regional anaesthesia
Consider whether neuraxial anaesthesia,
peripheral nerve blockade or infiltration with
local anaesthesia is an appropriate technique.
General anaesthesia: spontaneous ventilation
and non-intubation techniques
Patients requiring general anaesthesia who are
at low risk of aspiration may be suitable for a
spontaneous breathing technique, using face
Resources
Environment
Surgery
Patient
Airway Risks
You
Airway Emergencies
41
mask or standard laryngeal mask airway
(LMA). The Proseal™ LMA contains an
oesophageal port enabling insertion of a gastric
tube and drainage of gastric contents. A
number of reports support the designer‟s claim
that it provides better protection against
aspiration than the standard LMA, making it a
suitable technique in some circumstances
where the LMA is considered a relative
contraindication16, 17, 18.
Mechanical ventilation
via the LMA or Proseal ™ LMA is also
reported to be a safe and effective technique in
well selected patients19, 20, 21
.
General anaesthesia: endotracheal intubation
There are numerous indications for
endotracheal intubation including: reduce the
risk of aspiration, optimise gas exchange, or
enable a range of surgical requirements.
Endotracheal intubation is usually achieved via
direct laryngoscopy unless failed intubation is
highly anticipated. Indirect methods can be
employed as the primary plan when difficult
direct laryngoscopy is anticipated and the
anaesthetist is confident the patient can be
adequately oxygenated with bag and mask
ventilation. Numerous devices have proven
effective in achieving indirect intubation. The
intubating LMA (ILMA) has been evaluated in
a number of studies, and has a reported success
rate 95.7% when used
in patients without
difficult airways22
. It has also been used
successfully in patients who are anticipated to
be difficult to intubate 23,24,25
. Success rates
with the ILMA are improved when combined
with a flexible fibreoptic bronchoscope 26.
An
increasing range of techniques employing light
wands or fibreoptic video-enhanced
laryngoscopes is also available 27,28,29
.
Awake intubation techniques
Patients who have been assessed and
considered unsuitable for intubation under
general anaesthesia may be managed using
awake spontaneously breathing techniques
such as fibreoptic bronchoscopy 30
.
A comprehensive presentation of these
techniques is beyond the scope of this chapter.
In principle, anaesthetists should obtain as
much training and experience as possible
under elective conditions, to acquire know-
how with airway management techniques and
devices.
Road-testing and revising your primary
plan
Before you embark upon your plan you should
road test it. You might consult a colleague or
supervisor. Consultation with the surgical team
can greatly improve choice of technique,
particularly when the anaesthetist is unfamiliar
with the proposed surgical procedure or
surgical team. It is also good practice to
consult your assistant. The plan may not be
workable due to equipment, staffing or other
issues not apparent to you.
Contingency Plans
In the event of failure of the primary plan, the
contingency plan is the back-up approach
which you have decided to adopt if the primary
plan fails or complications develop.
Contingency plans require specific knowledge
of the patient and situation. They will be most
effective when they are easy to employ and
include clear criteria to guide their use.
Example: Difficult intubation
These principles are exemplified in algorithms
recently recommended by the Difficult Airway
Society (DAS) to guide management of
difficult and failed intubation 31
. They are not
intended to prescribe management of all cases
of difficult intubation; instead they provide a
plan for some specific, potentially serious
situations occurring in the adult, non-obstetric
patient. The algorithms use a common
structure, comprising four sequential plans
(labelled A-D). Their starting point is when
intubation is found to be difficult during direct
laryngoscopy in conjunction with general
anaesthesia (Figure 4).
In this context plan A, or tracheal intubation
via direct laryngoscopy, represents the primary
or preferred approach, as discussed in the
previous section. Conditions for intubation
should be optimised as part of the primary
plan, and specific bedside manoeuvres should
be employed to deal with the difficult
intubation. Only after this “best attempt”
should a failed intubation be declared. Before
progressing to the Plan B, the anaesthetist
should confirm he or she is able to ventilate the
patient with a bag and mask.
Airway Emergencies
42
Figure 4: Basic structure of DAS unanticipated difficult intubation flow-chart.
Airway Emergencies
43
The “best” attempt at intubation -
Optimising conditions and dealing with
difficult intubation before declaring it
failed.
The larynx should be intubated with as few as
possible attempts at laryngoscopy. As such,
conditions should, where possible, be
optimised to allow the first attempt to be a
“best attempt”. This applies during any
intubation, but is particularly important where
difficulty is anticipated. A number of
strategies have been recommended. These are
summarised in Box 2.
Box 2: Bedside strategies to improve success
with direct laryngoscopy
1. Optimise conditions before induction
a. Have equipment available and checked
b. Optimise bed height
c. Elevate head into the "sniffing position"
d. Educate your assistant in respect to the
plan, the technique and use of equipment
2. Consider calling for assistance (preferably
from an experienced anaesthetist)
3. Improve the view of the larynx
a. Ensure the muscle relaxant is working
optimally (assuming it is appropriate to
employ these agents)
b. Manipulate cricoid pressure. Return a
larynx, deviated by cricoid pressure, to the
midline. Reduce or remove cricoid
pressure if this is distorting the view of the
larynx
c. Apply optimal external laryngeal
manipulation
d. Ensure an appropriate type and size of
laryngoscope is used. Consider an
alternative blade size or type (e.g. McCoy)
4. Negotiate the ETT through a partial view of
the larynx
a. Rotate the ETT 90 degrees anticlockwise
b. Place an introducer through the ETT (do
not project past the end)
c. Ask an assistant to sublux the angle of the
jaw forward
d. Convert to a smaller size ETT
5. Intubate with a bougie
1 Modifying cricoid pressure. The larynx
can be inadvertently displaced to the
contralateral side by an over-enthusiastic
assistant. It is worth asking your assistant
to gently move the larynx from side to
side, if you cannot identify the midline
structures. Ensure he or she is directing
pressure directly backwards with pincered
fingers. Cricoid pressure can also limit the
view of a midline larynx and cause airway
obstruction32,33
. It may be worthwhile
asking your assistant to lessen the cricoid
by half, or even remove it altogether if the
best view obtained is inadequate or the
patient is difficult to ventilate by bag and
mask.
2 Optimal external laryngeal manipulation
(also known as „BURP‟ - Backward
Upright Rightward Pressure) is achieved
by placing the flattened fingers on the
anterior aspect of the neck over the thyroid
cartilage and pushing in the direction
described above. This is intended to bring
the posterior aspect of the larynx into view 34,35
.
3 Intubating with a bougie. The bougie may
be more effective than an introducer when
the best view of the larynx is grade 3 36
.
The bougie is considered most effective
when the tip is bent to 60 degrees 37
.
Intubation over a bougie or a fibreoptic
scope is facilitated if the laryngoscope is
kept in the mouth 38
, the ETT is small 40,41
and rotated 90 degrees anticlockwise 42
.
4 Bougies and introducers may be less
effective when the larynx is deviated from
the midline. It is worthwhile examining
CT scans prior to induction, to gain an
understanding of the position of the larynx.
5 A distorted laryngeal inlet may be
identified by observing gas bubbles
escaping from it. Gas bubbles can be
generated a gentle forced exhalation
achieved by an assistant by applying
controlled pressure to the chest wall,
synchronised with direct laryngoscopy.
Declaring the intubation failed Unfortunately there is no consensus among the
published guidelines strictly recommending
when an intubation should be declared „failed‟
by direct laryngoscopy 6,8,31,43
.
A number of the steps outlined above can be
employed during a single attempt at
laryngoscopy, however more than one attempt
may be required. As a rule of thumb you
should desist if the SpO2 falls below 90%,
check that the patient can be ventilated, and
restore the SpO2 to above 95% before the next
attempt.
Airway swelling and compromised
oxygenation may occur as a result of multiple
repeated intubation attempts. Thus your
Airway Emergencies
44
contingency plan should also guide the
maximum number of attempts that are
appropriate before you declare the intubation
failed. The ASA Task Force defines „difficult‟
intubation as occurring when “proper insertion
of the tracheal tube with conventional
laryngoscopy requires more than three
attempts or more than 10 mins”. 43
The DAS
recommends a maximum of four attempts
following a routine induction and three
attempts following a rapid sequence
induction31
, before intubation is declared
failed. Fewer attempts may be appropriate,
particularly if the operator is inexperienced,
when there is evidence of trauma, or where
conditions cannot be improved between
subsequent attempts.
Dealing with the failed intubation
The DAS Plan B and C represent the
contingency plans for declared failed
intubation. The DAS advises different
responses for three specific situations
involving unanticipated difficult intubation.
The flow-charts for each of these situations can
be found in the appendix to this chapter:
1. During elective surgery where the risk of
aspiration is low. Here Plan B involves
attempting tracheal intubation via indirect
methods, including those mentioned
previously in the section addressing the
primary plan (unless the surgery can safely
proceed without endotracheal intubation).
Plan C should be adopted if ventilation
becomes compromised. Plan C involves
cancelling elective surgery, oxygenating
the patient by bag and mask ventilation and
awakening him or her as soon as muscle
relaxation is reversible
2. During rapid sequence induction. In this
setting the high aspiration risk and
shortened duration of muscle relaxation
provided by suxamethonium make
secondary attempts at intubation both more
difficult and inherently dangerous. The
DAS guidelines suggest, therefore, omitting
plan B and proceeding immediately to
awake the patient (Plan C). A caveat to this
recommendation is the situation where the
risks of not proceeding with the surgery
exceed the risk of continuing without an
endotracheal tube. Here ventilation via a
Proseal LMATM
, a standard LMATM
or a
sealed face mask for the duration of the
procedure may be more appropriate than
aborting the procedure. Cricoid pressure
should be maintained, providing it is not
interfering with adequate oxygenation.
3. Failed intubation, increasing hypoxia and
difficult ventilation. This describes the
transition from a “can‟t intubate - can
ventilate” situation to a “can‟t intubate,
can’t ventilate” situation. As part of our
routine practice, anaesthetists commonly
manage partially obstructed airways with
basic airway management and a range of
simple airway devices including:
oropharyngeal and nasopharyngeal airways,
optimal two-handed face mask ventilation
and LMAs. Because invasive rescue
procedures are technically difficult and are
associated with serious complications, the
basic non-invasive strategies should be
employed to maximum effect before
progressing to the invasive “rescue”
strategies outlined in Plan D.
DAS Plan D involves the implementation of
invasive rescue techniques in the setting of a
“can‟t intubate, can‟t ventilate” situation.
These include cannula cricothyroidotomy and
the emergency surgical airway. The time-
critical, “last resort” nature of plan D suggest
that plan D, and the transition from Plan C to
Plan D, are more representative of emergency
planning. Consequently these are elaborated in
the following section, „Emergency Plans‟.
While the DAS algorithm presents each of
Plan A-D as discrete phases, in practice, we
may ventilate with a bag and mask on several
occasions during airway management and
may, on occasion, move to and fro between
these phases. As previously stated, these
algorithms are designed for specific situations
and carry certain assumptions. In reality, there
may also be a number of variations on Plan B
and Plan C appropriate for a particular
situation. The specific method used is not as
important as the forethought that occurs prior
to embarking on your primary plan and your
preparedness to employ an appropriate
contingency plan.
Emergency Plans
As described in the above section, the DAS
algorithms (Plan C and D) provide a strategy
for managing increasing hypoxia associated
with a failed intubation. This section elaborates
Airway Emergencies
45
this strategy, also addressing a broader range
of situations which can potentially be
associated with hypoxia.
Hypoxia can be caused by airway obstruction
or impaired gas exchange associated with a
patent airway. They both occur commonly, and
commonly co-exist. One may conceal signs of
the other. Failure to distinguish the relative
contribution of each may lead to serious
morbidity.
Your starting point may be one of the
following situations:
When the patient is not intubated. For
example, in the pre-anaesthesia induction
room, post-anaesthesia recovery room or
outside the operating suite. A sequential
approach should be used to identify and
treat airway obstruction, followed by
treatment of compromised gas exchange.
During intubation - A “Can‟t intubate -
Can‟t ventilate” situation. This follows the
same principles as those for unintubated
patients. Strategies to manage airway
obstruction are addressed in DAS Plans C
and D. A variation of the algorithm
specific for this situation has been
published (Figure 5).
Following intubation, where there is a
concern about ventilation or oxygenation.
This situation may occur during induction,
maintenance, or emergence from
anaesthesia, during transport of critically
unwell patients, or in patients who have
been intubated outside of the operating
theatre environment. Management must
include a systematic elimination of
problems arising 1) in the ventilation
circuit (above the airway), 2) in the
breathing tube (in the airway) and 3) with
ventilation or gas exchange (below the
airway). This situation is addressed
further in the chapter on Anaesthetic
Emergencies.
Upper Airway Obstruction
In the majority of situations obstruction results
from „functional‟ reduction in muscle tone in
the supraglottic region in a patient who is
either pharmacologically sedated, has a
reduced level of consciousness or has been
administered muscle relaxants. “Anatomical”
obstruction presents less frequently and
reflects compression of the pharynx, laryngeal
inlet or trachea by an inflammatory mass,
haematoma or other discrete mass. The
features of airway obstruction are shown in
Box 3.
Box 3: Recognition of Upper Airway Obstruction
Look, Listen & Feel for: Consider patient unstable if
*:
Chest wall excursion Absent or “see-saw”
Expired gases Reduced
Oxygen saturation SpO2 < 90%
Functional Obstruction Sedated or comatose
(sedation, narcotisation,
coma)
Snoring, periodic
breathing
Anatomical Obstruction
(post surgical swelling,) Patient alert,sits forward
haematoma, foreign body,
traumatised larynx)
Dysphagia, dysphonia,
dribbling
Reduced airflow rate
Stridor (supraglottic
obstruction)
Prolonged expiratory
flow rate > 3 L/sec
(tracheal obstruction)
* These parameters are presented as a guide.
Assessment should take into consideration patient trends
and co-morbidities.
Functional Obstruction
The immediate response is structured on
graded intervention (Figure 5). After each step
the patient should be re-assessed. Reversible
causes should be excluded. These include
foreign body, drug-induced sedation, and
residual muscle relaxation.
Simple measures should be employed before
progressing to invasive “rescue” measures.
These include:
1. Position the head in the sniffing position
(neck flexion and head extension).
2. Apply maximum jaw thrust and chin lift.
3. Insert an oropharyngeal or nasophayngeal
airway.
4. Ensure a correctly sized mask is used.
5. Reduce leaks around the mask in
edentulous patients by abutting the skin
around the mouth with the mask (a third
hand is required). Leaks around beards may
be reduced by applying dressings, such as
Op-site™, over the beard.
6. If the airway remains obstructed the
anaesthetist should use two hands to
position the mask and ask an assistant to
Airway Emergencies
46
apply positive-pressure ventilation with the
bag.
7. Depending upon the circumstances and
recent history, it may be appropriate to have
a single attempt at intubation via direct
laryngoscopy. Conditions should be
optimised as described in the section on
contingency planning. Further attempts to
intubate are less appropriate if repeated
unsuccessful attempts to intubate have
recently occurred.
8. The LMATM
and more recently the Proseal
LMATM
are recommended as devices to
support ventilation in an obstructed
airway44, 45
. Some data also supports the
efficacy and safety of the Combitube™
when used appropriately46,47.
However the
incidence of complications is higher,
including oesophageal rupture 48,49.
9. As a final step, an emergency surgical
airway via the cricothyroid membrane is
recommended. Surgical airways carry
significant risks and should only be
considered in the event of actual or
imminent life threatening hypoxaemia
where other options are limited.
Airway Emergencies
47
Figure 5. DAS Flow-chart for ”can‟t intubate, can‟t ventilate” situation.
Airway Emergencies
48
Rescue ventilation via cricothyroidotomy or
a surgical airway
Oxygenation via a subglottic approach is
indicated when critical airway obstruction and
hypoxaemia exist. Formal tracheostomy and
percutaneous tracheostomy are likely to
contribute to excessive delays in oxygenation,
which will be best achieved with an airway
device inserted through the cricothyroid
membrane. The goals of treatment are in
descending order of importance:- 1) delivery
of oxygen, 2) exhalation to avoid gas trapping
and facilitate removal of carbon dioxide (CO2)
and, 3) protection of the lungs from aspiration
of stomach contents or blood.
Three approaches are described: cannula
cricothyroidotomy with percutaneous
transtracheal jet ventilation, surgical
cricothyroidotomy with insertion of a cuffed
endotracheal tube, and percutaneous
cricothyroidotomy via a small diameter
uncuffed tube. The first two approaches are
more widely recommended 31, 50
.
Cannula cricothyroidotomy with percutaneous
transtracheal jet ventilation
This approach may provide temporary
oxygenation when the airway is obstructed at
the level of the glottis or above. The device is a
large bore intravenous cannula inserted
through the cricothyroid membrane, in its
lower third and directed caudad at 45 degrees
to the coronal axis. Identification of the trachea
is facilitated by aspirating air via a syringe as
the cannula is inserted, and reconfirmed after
the cannula is advanced. A low compliance,
high-pressure ventilation source (40psi)
capable of delivering >40 L/min is necessary 51,52
. This can be delivered by a purpose-
designed jet insufflation device. Alternatively,
a make-shift system can be assembled using a
standard intravenous giving set connected via
oxygen tubing to a high pressure oxygen
source. Options include direct attachment to a
cylinder or wall outlet or connection to the
common gas outlet on the anaesthetic machine
via a 6mm ETT connector. This approach
provides no protection against aspiration.
Suboptimal elimination of CO2 is a further
disadvantage. Kinking of the cannula will
result in obstruction to the gas flow and thus
loss of oxygenation. Gas trapping may occur
if there is no route for exhalation via the upper
airway. Displacement of the cannula can result
in subcutaneous air.
Surgical Cricothyroidotomy
Insertion of a cuffed endotracheal tube achieves
all the three goals listed above. Ventilation can
be achieved via a standard low pressure
ventilation device. A small cuffed ETT (6.0 mm
OD in an adult) is introduced via a horizontal
incision in the lower third of the cricothyroid
membrane. Entry can be facilitated by opening
the incision with artery forceps or a scalpel
handle. The risk of creating a false passage
may be reduced if the ETT is passed over a
bougie53
.
Percutaneous Minitracheostomy
Percutaneous devices potentially achieve better
oxygenation and ventilation than intravenous
cannulae. They generally have an internal
diameter of 4 mm, the critical diameter needed
to achieve an exhalation time of less than 4
seconds54
. They achieve high minute volumes
using low pressure ventilation circuits. They
provide minimal protection against aspiration.
Gas may escape upwards through the glottis if it
is only partially obstructed and paradoxically,
ventilation may be facilitated by not actively
achieving patency of supraglottic structures.
There are a number of commercially available
devices. Operators should acquaint themselves
with the components and respective insertion
techniques of these kits, which vary.
Anatomical Obstruction
Patients with airway obstruction caused by
discrete supraglottic or glottic masses or
swelling are generally alert and will not
tolerate the steps suggested in the functional
pathway. These patients require early
conservative intervention including:
1. Minimum handling. They often prefer to sit
forward.
2. Apply O2 therapy via a face mask.
3. Nebulised adrenaline may temporarily
reduce oedema, if present, and should be
considered.
4. Patients with a haematoma following neck
surgery may benefit from release of sutures
while preparing for definitive management.
5. If at any time the patient becomes
unconscious then treatment should be as
described in the preceding section,
„Functional Obstruction‟. As with
functional obstruction, the emergency
surgical airway should be considered if life
Airway Emergencies
49
threatening hypoxaemia is imminent and
other less invasive options are limited.
6. Definitive management by experienced
personnel should be expedited. Definitive
management may require a further surgical
procedure (e.g. exploration of bleeding) or
insertion of a tracheal tube until oedema
settles.
7. The appropriate anaesthetic technique will
depend upon the underlying problem,
urgency, co-morbidities and resources.
Decision-making should follow appropriate
consultation with senior anaesthetists,
surgeons, and other specialists depending
upon the patient and location.
8. Anaesthesia techniques used to achieve a
definitive airway have included:
a. Direct laryngoscopy following gaseous
induction of general anaesthesia.
b. Awake fibreoptic intubation
c. Formal tracheostomy or percutaneous
tracheostomy under local anaesthesia.
Impaired Gas Exchange Associated With a Patent Airway
Gas exchange can be compromised by
numerous conditions. These may be
physiologically classified into three groups 55,56,57
:
1. Type I respiratory failure (hypoxaemia
without hypercapnoea). Anaesthetic
causes include endobronchial intubation,
foreign body, atelectasis and pulmonary
oedema. Co-morbid conditions include:
segmental collapse, atelectasis, pulmonary
venous congestion, consolidation and
aspiration pneumonitis. Severe V/Q and
structural abnormalities of the heart can
cause right to left shunt. The cardinal sign
is hypoxaemia and an elevated A-a
gradient. Respiratory acidosis is typically
evident on arterial blood gas analysis. CO2
may be elevated when the V/Q mismatch
and hypoxaemia are severe. However,
relative hypoventilation may co-exist if the
patient is unable to increase his or her
minute ventilation to compensate, due to
respiratory muscle dysfunction, fatigue or
reduced respiratory drive.
2. Type 2 respiratory failure (hypercapnic
respiratory failure). Results from a
decrease in minute ventilation. Conditions
associated with hypoventilation can
involve impaired central or peripheral
neurological control of respiration,
decreased chest wall compliance, or
weakened muscles of respiration.
Anaesthetic causes include sedation, chest
wall loading, and residual neuromuscular
blockade. Co-morbid conditions causing
hypoventilation include coma,
neurological conditions, myopathies, and
increased airway resistance resulting from
bronchoconstriction. These disorders are
characterised by CO2 retention, evidence
of suppressed ventilatory drive, poor chest
wall function, hypoxaemia resulting from
reduced alveolar ventilation and a normal
A-a gradient. Respiratory acidosis is
typically evident on arterial blood gas
analysis.
3. Space occupying lesions within the pleural
cavity. Examples include pneumothorax
and haemothorax. Characteristic signs
include asymmetric chest wall movement
and breath sounds and a deviated trachea.
Assessment
Signs of impaired gas exchange are shown in
Box 4.
The patient‟s level of consciousness and work
of breathing are important criteria of severity,
however these must be interpreted within the
context of the situation and recent trends. For
example, drowsiness can represent either the
cause or the result of respiratory depression.
Treatment A number of specific and non-specific
treatments may be useful in supporting this
Box 4: Recognition of Compromised Breathing or
Ventilation
Look, Listen & Feel
for:
Consider patient unstable
if*:
Ventilatory drive Respiratory rate <5 or
>36 bpm
Increased work of
breathing
Use of accessory muscles
Abnormal breath sounds Wheeze with reduced air
entry, widespread
crepitations
Oxygen saturation SpO2 < 90%
CO2 retention PaCO2 > 50 mmHg
Fatigue Drowsiness, exhaustion
*These parameters are presented as a guide. Assessment
should take into consideration co-morbidities and trends
Airway Emergencies
50
group of patients. Treatment should be guided
by the functional effects of the problem.
The principles of immediate treatment are the
same for all patients and fall into four
categories:
Oxygen therapy. This should be given
early to all patients with hypoxia. This can
be given at high flow unless there are
specific concerns about exacerbating CO2
retention. Under these circumstances the
inspired O2 concentration can be restricted
with fixed O2 delivery devices or by using
nasal prongs at 2-3 L/min. Hypoventilation
and low V/Q generally show a good
response to O2 therapy. Severe V/Q
mismatch causing shunting may show a
poor response to O2.
Improved alveolar ventilation. This
improves oxygen transfer by removing
retained CO2 and exchanging this with O2
in the alveoli which is then available for
transfer into the blood. It is particularly
useful in hypoventilation (Type 2
respiratory failure). It can be achieved by
reversing factors that are depressing
ventilation (e.g. drugs) and by providing
inspiratory pressure support. In the
operating theatre we commonly employ
intermittent positive pressure ventilation
via an endotracheal tube. In other
circumstances respiratory support can be
more appropriately achieved with non-
invasive pressure support via a purpose-
designed face mask, such as Bi-level
Positive Airway Support (BiPAP).
Positive expiratory pressure. This
improves oxygen transfer by preventing or
reversing alveolar collapse, thereby
increasing the surface area for O2
exchange. It may be effective in patients
with V/Q mismatch (Type 1, respiratory
failure). It can be administered to
spontaneous breathing patients via
continuous positive airway pressure
(CPAP) or as positive end expiratory
pressure (PEEP) in association with
intermittent positive pressure ventilation or
pressure support ventilation.
Reverse specific causes. Depending upon
the cause and severity of the underlying
condition, the patient may require specific
targeted treatment as a matter of urgency.
Examples include denitrogenation and
pleurocentesis for pneumothorax or
administration of bronchodilators to
manage severe bronchconstriction.
Summary
Airway obstruction occurs commonly in the
routine provision of anaesthesia. It can be
difficult to distinguish from other causes of
hypoxia, and several causes may coexist.
Forward planning and preparation will avoid
or mitigate the consequences of airway
obstruction. Responding to more serious
events using a rehearsed, systematic approach
will improve the anaesthetist‟s performance,
and that of the team. In retrospect, the patient
will be viewed to have received appropriate
care, irrespective of the outcome.
Airway Emergencies
51
Appendix 1 : Difficult Airway Society Algorithms
Airway Emergencies
52
Airway Emergencies
53
Airway Emergencies
54
Appendix 2 : Surgical Airway Anatomy
The cricothyroid membrane is directly
subcutaneous to the skin. It is about 9mm in
height and 3cm in width. It usually lies one to
one and a half fingerbreadths below the
laryngeal prominence. Alternatively it can be
located by placing your small finger into the
patient‟s suprasternal notch, followed by
placement of the ring, long, and index finger
adjacent to each other in a stepwise fashion up
the neck, with each finger touching the one
below it. When the head is in the neutral
position, the index finger is usually on or near
the cricothyroid membrane.
Structures at risk of injury - The cricothyroid
membrane is often crossed horizontally in its
upper third by the superior cricothyroid
arteries. To minimise the possibility of
bleeding, the cricothyroid membrane should be
incised in its inferior third. The anterior jugular
veins run vertically in the lateral aspect of the
neck and thus also escape injury. Because the
vocal cords are usually located one cm or more
above the cricothyroid space, they are not
usually injured during emergency
cricothyroidotomy.
Choice of techniques
Three techniques are described:
1) Transcricoid jet ventilation via an
intravenous cannula,
2) Conventional ventilation via a purpose
designed percutaneously inserted
minitracheostomy catheter (internal
diameter size 4mm)
3) Conventional ventilation via a small cuffed
endotracheal tube, inserted via a scalpel-
made incision through the cricothyroid
membrane.
Each technique is acceptable. The DAS now
recommends (1) or (3) over (2). The choice of
technique should be made on the basis of the
risks and benefits of each technique, the
patient‟s circumstances, the operator‟s
experience and resources available.
Risks and benefits
The benefits, in order of importance are
oxygenation, gas exchange and protection of
the lungs from aspiration of stomach contents.
The risks of these procedures can be divided
into insertion problems and ventilation
problems.
Insertion problems include: Bleeding and
difficulty passing the airway device.
Damage to the larynx, trachea, or
surrounding structures (arteries, veins,
oesophagus, pleura).
Ventilation problems include: Ineffective
ventilation and barotrauma.
If the airway obstruction is in the mid to
lower trachea or bronchus, none of the
catheters used in these techniques will be
long enough to bypass the obstruction. A
rigid bronchoscope may be the only means
to bypass obstruction.
Transcricoid jet ventilation by an
intravenous cannula
Technique
In order to perform cannula cricothyrotomy
you must first firmly fix the trachea firmly
between your thumb and middle finger. You
could consider using a 22g seeker needle first
to locate the “air tube” in patients with difficult
anatomy. After feeling for the cricothyroid
membrane insert the cannula with a 2ml
syringe attached through the membrane at an
angle of 45 degrees towards the feet. As soon
as you can aspirate air, slide off the cannula off
the stylette, until the hub reaches the skin,
then, remove the stylette and syringe. Check
that you can still aspirate air from the cannula.
You must never let go of the cannula because
it is extremely difficult to secure and maintain
in the proper position.
Risks
Displacement of the cannula may result in
subcutaneous air (this will remove all your
landmarks making it impossible to find the
cricothyroid membrane).
Kinking of the cannula will result in
obstruction to the fresh gas flow and loss
of ventilation. This is more likely with
smaller cannulae. The skin is one of the
main causes of catheter-kinking, so a small
skin incision is recommended before
cannula insertion.
Advantages
It can be used to temporarily oxygenate
patients.
Anaesthetists may be more confident than
with the other two techniques.
Disadvantages
Gas exchange is inferior to the other two
techniques.
Airway Emergencies
55
It provides no protection against aspiration
Ventilation circuit and equipment
Ventilation must be achieved via low
compliance circuit attached to a high
pressure oxygen source (40psi) capable of
delivering >40 l/min.
Several options exist including
commercially available purpose designed
jet insufflator or adapting ready-at-hand
equipment. The key components comprise:
non-compliant tubing (standard IV giving
set, green oxygen tubing); a release valve
for exhalation (cut off tubing bung, 3 way
tap, etc) and a connector to O2 source (IV
sets will connect to green O2 tubing; green
O2 tubing can be connected to the common
gas outlet of an anaesthetic machine via a
connector for paediatric circuits, or a size 6
ETT connector).
Management
You must see the chest rise and fall as in
normal resting ventilation. Continue to
maximise the patency of the upper airway
by allocating a skilled person to deliver
continuous O2 via a face mask (so that any
entrained air will be oxygen rich) in
addition to airway opening manoeuvres
(nasal and Guedel airways, jaw thrust and
head tilt).
Manage complications:
Percutaneous Minitracheostomy.
Technique
There are a number of Percutaneous
Minitracheostomy sets on the market, size
ranges from 4mm in diameter and larger. Some
of the larger tubes have cuffs and the tube
lengths also vary with different makes. Some
kits combine the dilator and introducer all in
one (Melker), this means one less time
consuming manoeuvre. You should be familiar
with your hospitals device.
First locate the cricothyroid membrane with
index finger and hold the trachea firmly
between thumb and middle finger. Make a
vertical skin incision over the cricothyroid
membrane, this can be easily extended up or
down if the relationship of the skin with
cricothyroid membrane changes. It is
recommended that the skin incision be made
first for two reasons:- the 16g cannula is more
likely to kink if there is no skin incision,
making it difficult to pass the guide wire.
Secondly, the dilator will not advance though
intact skin. After the skin incision, the 16g
cannula or 16g needle is inserted 45‟ caudally
with a syringe attached. The airway is
positively identified by air aspiration.
The floppy end of the guide wire is then
inserted thought the cannula or needle, the later
is then removed leaving only the wire in the
airway. A dilator is then passed over the wire
into the airway, after this has been removed the
catheter and introducer are advanced together
into the airway with a slight rotatory motion.
The catheter is advanced over the introducer
into the airway and then the wire and introducer
are removed. This technique is similar to
central venous line cannulation. Most kits have
no cuff, so they do not provide any airway
protection.
Secure catheter with suture or trachy tape.
Suction down to maintain patency.
Risks
Some Percutaneous Minitracheostomy kits have
a short catheter, which is liable to dislodge with
patient movement especially in patients with
short obese necks.
The smaller size 4 catheters are quicker and
easier to place than a larger cuffed size 6
catheter, because less dilatation of the
cricothyroid membrane is needed. In hypoxic
patients time is of the essence so we
recommend using an uncuffed 4mm catheter.
If ventilation is found to be inadequate with a
4mm catheter (because the inspired gas is
escaping via the mouth) a jet insufflator can be
used to achieve adequate ventilation.
Advantages
Oxygenation and gas exchange achieved,
depending on internal diameter of cannula
Disadvantages
Uncuffed ETTs provide no protection form
aspiration however airway protection can
be improved with a pharyngeal pack.
Ventilation circuit and technique
Assuming a cannula internal diameter of 4mm
or greater, ventilation is achieved with a
standard anaesthetic circuit.
Ventilation will be reduced if gas leaks
retrogradely through a patent airway.
So adequate inspiration is only achieved if the
upper airway is obstructed, either through
disease or artificially by allowing the tongue to
fall backwards and obstruct the upper airway.
Surgical Cricothyroidotomy.
Technique
Try to keep head fixed in the midline by helper
(inline stabilisation). Fix thyroid cartilage
Airway Emergencies
56
firmly so that it does not move when patient
moves.
Make horizontal incision though the lower third
of cricothyroid membrane and then dilate this
incision with the handle of the scalpel or artery
forceps. Insert a small cuffed ET tube though
the hole. Bubbles of air will identify the space,
blood will also provide lubrication.
A bougie can be used and ET tube railroaded
over in-order to make a more controlled
intubation of the airway without creating a false
passage.
Risks
There is a potential to make the scalpel
incision into the wrong structure e.g.
carotid artery. Make the incision in the
lower third of the space, horizontally.
Advantages
Achieves oxygenation, gas exchange and
protection best of the three techniques
Ventilation circuit and technique
Ventilation is achieved with a standard
anaesthetic circuit.
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Airway Emergencies
59
ANAESTHETIC EMERGENCIES
Assoc Prof Jennifer Weller
Overview
Managing a life-threatening emergency in the
operating room can be a daunting prospect.
We use complex equipment and monitoring,
our patients often have severe underlying
pathology, the surgical insult can cause sudden
and profound physiological derangement, and
the drugs we employ can have impressive and
unpredictable side effects. The clinical signs
are often poorly defined, there is pressure of
time and multiple tasks to perform, making it
difficult to think clearly and logically.
Although the number of things that can go
wrong seems unlimited, adverse events tend to
present in a limited number of ways. Our
patients frequently present with hypoxia,
hypotension or hypertension, rhythm
disturbance or ventilation problems. Working
out what to do can be challenging in this
complex and dynamic environment.
Developing a systematic approach to these
generic conditions may be a useful strategy to
assist diagnosis and management of crisis
events.
In addition, the teamwork and behavioural
factors discussed in the Human Factors
Module can be crucial in our ability to
implement an effective management plan.
The objectives of this module are to:
Develop an immediate response to a
critical situation.
Improve management of crises by
optimising the use of the operating
room team.
Identify behavioural strategies to
improve diagnosis.
Develop a systematic approach to
critical events in the operating theatre.
Anaesthetic Emergencies
60
An Immediate Response to a Crisis
As junior doctors we are taught the ABC of
resuscitation. Think how often this has come
to your rescue. It is a pre-compiled
response, widely applicable, it doesn’t
require thinking, it can be done even in a
state of panic, it may yield vital information
and it may be lifesaving. Although there is
some resistance by doctors to practising by
algorithm, there is a time and a place, as
illustrated by this simple and memorable
resuscitation algorithm. In anaesthesia, the
clinical context is altered. We are not dealing
with a patient who has spontaneously
collapsed, but a patient under anaesthesia.
We need to include this in our version of the
resuscitation algorithm. Have you ever come
to help at a cardiac arrest in theatre and
found the patient still receiving volatile
agent? The following adaptation of the basic
ABC of life support is modelled on David
Gaba’s “Initial Response to a Serious Event”
(Crisis Management in Anesthesiology, 4)
The Anaesthetists’ ABC A=Airway and Anaesthesia
Check airway. Turn off all anaesthetics in
use and double check
B=Breathing
Give 100% oxygen AND verify
Maintain oxygenation at all costs. Consider
Ambubag, alternative O2 source
C=Circulation
ACLS, fluids and vasopressors as necessary.
Double-check vasodilator infusions.
Developing Skills in a Working Team
This module provides an opportunity to
apply the principles of crisis management
described in the human performance module.
What does teamwork involve? Think of a sports team. Aspects of teamwork
include: communication, leadership, a
common goal, a plan, working together,
utilising skills of team members. Think how
this relates to the operating room team?
4 Gaba DM, Fish KJ, Howard SK. Crisis Management in
Anesthesiology. New York: Churchill Livingstone; 1994.
What sort of communication works? Your tone of voice, and the clarity of instruction
influence the outcome. Communications should
be directed to a specific person. Avoid asking
the room in general for a defibrillator. Everyone
or no one may go. It‟s a useful strategy to learn
the names of your team. Ensure your requests
have been acknowledged and accepted. Conflict
can arise. Focus on what‟s right for the patient,
and save the arguments for after. Avoid
judgemental comments (What have you done?!)
Your team may become less helpful.
Listen. Be open to suggestions from the team.
What is the role of the leader? Reflect on your role as leader in a clinical crisis
in the operating theatre. Your tasks may include
decision making, prioritising, organising the
team, and re-evaluating the situation. The leader
should be the clearing-house of ideas from the
team, centralising communication and
coordinating the team‟s activities. The leader
should have a global view of what‟s happening.
The problem leader
Think of your experience in theatre. What sort
of leadership behaviour is likely to cause
problems in a crisis? You may include the
following:
Weak leadership: Failure to take control of the
situation: no directions to team, no plan.
Authoritarian figure: The team may be afraid to
offer suggestions, alternatives or point out
problems for fear of the consequences.
All-knowing leader: The team may be
discouraged from offering input as they assume
the leader is all-knowing, all-powerful and
doesn‟t need their suggestions.
Think what your ideal leader would behave like.
What should the leader be doing?
Think of a well-run cardiac arrest call, a well-
rehearsed trauma team call, or a major operating
room crisis. What has the leader been doing?
Standing back allows the leader to take a
global view, allows him or her to plan,
prioritise and co-ordinate the team. Focusing
on one aspect of care such as airway
management or vascular access can make it
difficult or impossible to take this global view.
How do you organise your team?
Identify the tasks that need to be done and
allocate them appropriately. In netball, it would
be a poor plan to put your best goal shooter in
defence. In an operating room crisis, sending
Anaesthetic Emergencies
61
your tech out for blood instead of the student
nurse, getting your anaesthetic colleague to
keep a record of the evolving crisis while
you put in the central line would also be less
than optimal task allocation. Once you’ve
handed out the tasks, check that the team is
coping with the tasks they’ve been given.
Key points of Teamwork:
Communicate effectively
Clear, concise, directed
Two-way, open
Centralised
Leadership
Stand back, take a supervisory role
Allocate tasks appropriately
Prioritise
These skills require practice. Don’t wait for
the next emergency or next EMAC course.
Practice them on a daily at work.
Behavioral Strategies to Improve Diagnosis
What can we do to support diagnostic
decision making under pressure?
Problem solving requires thinking. Although
the ability of humans to problem solve is a
powerful process, it requires a great deal of
mental effort and is vulnerable to stress and
overload. Certain behavioural strategies,
including re-evaluation and verbalising may
assist this process of deductive problem
solving.
There is some evidence that we make a
diagnosis by matching the available
information to a pattern in our long-term
memory compiled from past experience.
With only limited data, we tend to match the
problem to approximate to the nearest match.
Increasing the available information, may
improve the match. How do we gather this
information?
Vigilance
If we’re not looking, we won’t see.
Vigilance can deteriorate under such
conditions as fatigue, boredom or distraction.
Should we consider personal strategies to
minimise the effects of these factors, such as
routine scanning? Do you have a strategy to
combat fatigue?
Allocate attention wisely
We can only attend to a limited number of pieces
of information at once. It’s easy to overlook
something if we’re concentrating on one
particular task such as inserting a central line or
teaching a medical student.
Off-load tasks
Off-loading tasks can aid problem solving by
giving us more thinking space. By allocating a
whole task area such as fluid resuscitation or
airway management to a colleague, we can take
a global view of the crisis. Stand back and take
a supervisory role.
Verbalise Talking out load can assist your own thinking.
Also, as you re-evaluate the problem, you let the
other members of the team know what you’re
thinking, what you’ve considered and what you
can’t work out. They are brought up to speed,
may see things you’ve missed or misinterpreted,
or come up with a new suggestion. Consider
what it’s like trying to help a junior doctor with
an endotracheal intubation if they don’t say what
they’re seeing, what problem they’re
encountering. It’s hard to offer suggestions.
Share the problem
How does a colleague help with diagnosis? They
may have a new perspective. A more detached
assessment may spot something you’ve missed.
Are certain ways of conveying the problem to
responders more useful than others? If, as a
helper, we’re given a description of the event
rather than diagnosis we can form our own
conclusions. We may avoid going down the
same track in a fixation error. Consider how you
convey information to a colleague when they
come to help.
Re-evaluate
Did the action plan work? Is the problem getting
better? Are there any side effects of treatment?
Are there additional problems? Was the initial
diagnosis correct? Am I repeating the same
interventions and not solving the problem?
These considerations may help us detect or avoid
fixation errors.
Strategies to improve diagnosis
Be vigilant
Allocate attention wisely
Offload tasks
Verbalise
Share the problem
Anaesthetic Emergencies
62
A Systematic Approach to Crisis Management
In a crisis, we need to gather all the relevant
information. Problems arise when we
overlook important information. It’s easy to
miss information in the stress of a crisis.
Do we need a system to gather this
information to avoid missing something?
The presentation is often generic, for
example, hypoxia, high airway pressure,
abnormal CO2, tachycardia, or hypotension.
A simple, memorable systematic approach
for these specific generic events could
include improve information gathering and
diagnosis. An example could be a spatially
oriented approach to the identification of the
cause of high airway pressure e.g. machine-
circuit-airway-lungs-pleural cavity, chest
wall. COVER ABCD A SWIFT CHECK
(Runciman, 1993) is a well known
systematic approach to diagnosis of any
adverse event. A written cognitive aid may
support memory.
What algorithms do you find helpful? First
you have to remember them, and do this in
the stress of a crisis. Alternatively you could
have a written memory aid. A system that
makes sense to one person may be an enigma
to another. A few generic approaches are
suggested in the appendices. You may want
to develop your own. It is important to
rehearse these algorithms to ensure they can
be implemented swiftly and securely when
the need arises.
Advantages of a systematic approach to diagnosis and treatment in a crisis
A systematic approach covers the likely
and or life-threatening causes quickly and
comprehensively.
Cognition is impaired in a crisis. The use
of a rehearsed response reduces the
amount of thinking required and may
solve the problem.
“Freezing under fire”: an automatic
response can provide a fallback routine
for the panic stricken. It should at least
ensure initial life-saving interventions are
instituted.
A systematic approach encourages
examination of all relevant data and
repeated re-evaluation of the situation.
Confirmation bias in perception of data,
and fixation errors are frequent. You see the
information you want in order to confirm
your diagnosis. (It is, after all, very
uncomfortable not knowing what the problem
is.) A systematic review of data may help
avoid these errors in cognition.
A systematic approach can be rehearsed,
promoting a rapid, streamlined performance.
The systematic approach in context
A systematic approach may delay effective
treatment.
We have all been in a situation where a problem
arises; a diagnosis is made in seconds and
treatment instituted rapidly and effectively
without any consideration of alternative
diagnoses.
We have a tendency to go for the most likely
cause straight away and treat it. This is referred
to as frequency gambling. By definition, more
often than not frequency gambling pays off.
Experience is likely to improve the odds.
Delaying the obvious treatment by following a
rigid sequence of checks will cause delay.
However, frequency gambling only works if we
have jumped to the correct conclusion.
Persistence with an incorrect diagnosis is an
example of a “fixation error”. (See: Human
Performance Issues). If we are convinced of the
diagnosis, there is a tendency to only see
information that supports that diagnosis
(confirmation bias).
If a problem is not immediately fixed by
addressing the most likely cause, re-evaluate
using a systematic approach and make sure
something is not being missed. It may even be
appropriate to delegate this review to a skilled
assistant who may take a more objective
approach.
A systematic approach may not work for
unpredicted events.
Another limitation to an algorithmic approach is
that we can only make plans for predicted
eventualities. A procedures manual will not
address an unforeseen event.
Limitations of a systematic approach
Only works if you remember it.
Only useful for predicted eventualities.
Working through a procedure checklist may
delay management.
Rehearsal of systematic approach
A systematic approach needs to become
Anaesthetic Emergencies
63
automatic or we’re back to the laborious
process of thinking from first principles. For
each routine case, it could be helpful to
mentally rehearse for possible problems.
This could also provide an in-theatre
teaching option that focuses attention on the
case in hand rather than potentially
distracting from patient care.
Summary
Core knowledge and skills are basic
requirements for effective crisis
management. In addition to the opportunity
for rehearsing for uncommon events, this
module aims to explore how to behave in a
clinical crisis, and to think about how we
think. The simulated events provide an
opportunity to practice new strategies.
The appendices offer some specific
systematic approaches to generic crisis
presentations. You may wish to develop your
own approaches to these problems.
Suggested Reading Benumof L, Saidman LJ. Anesthesia and
Perioperative Complications. 2nd
Ed, 1999, Mosby:
New York.
Bognor, M. S. Human Error in Medicine. 1994,
Lawrence Erlbaum Association Inc: New Jersey.
Gaba, DM, Fish, KJ, Howard, SK. Crisis
Management in Anesthesiology. 1994, Churchill
Livingstone:Philadelphia.
Reason, J. Human Error. 1990, Cambridge
University Press: Cambridge.
Boud D, Keogh R, Walker D. Reflection: Turning
Experience into Learning. 1985,
Routledge:Abingdon.
Anaesthetic Emergencies
64
Appendices
The Hypoxic Patient
Definition of hypoxia: SpO2 < 90%, PaO2< 60mmHg or SpO2 falling by
>=5%
Detect cyanosis at SpO2<85%, PaO245-50mmHg
Deoxygenated Hb>5gm/100ml
Consider:
Patient context (high requirement, poor O2
delivery, chronicity of low SpO2, surgical
procedure, position, pre-existing disease-
respiratory, cardiac, renal, liver, obesity)
Why is the SpO2 below normal or falling? It
seems prudent to investigate early
Initial response to a crisis: The anaesthetists
ABC
Treat the hypoxia while looking for the cause
Don’t assume artefact
Verify hypoxia is real
Systematic approach to diagnosis of hypoxia:
O2 supply
Check pressure gauges, flow meters, FIO2,
vaporizer housing
Anaesthetic machine
Check ventilator: VT, rate, airway pressure gauge
Circuit: connections, one-way valves, filter
Airway
Exclude obstruction: In unintubated airway, filter,
and airway devices. Check for secretions. Pass
suction catheter down ETT and make sure it goes
beyond end of ETT
Ventilation
Exclude endobronchial intubation, look and listen
for bilateral chest expansion, adequacy of minute
ventilation, bronchospasm, recheck airway pressure
gauge, exclude pneumothorax
Lungs
Gas exchange problem: aspiration, pulmonary
oedema, bronchospasm, consolidation, and
atelectasis
Pulmonary embolism -air, thrombus, fat
Blood
Circulation: Low cardiac output
Anaemia: Reduced O2 carriage, high O2 extraction
and decreased mixed venous PO2
Tissue Uptake
Increased metabolism (fever, thyroid crisis, etc)
O2 supply
anaesthetic machine
circuit
airway
ventilation
lungs
blood
tissue uptake
Anaesthetic Emergencies
65
High Airway Pressure
A systematic approach to high airway pressure:
Consider the patient context: surgery, pre-
existing disease, prior events, risk factors. High
airway pressure will present in several ways:
Problem ventilating the patient (e.g.
decreased compliance in breathing bag, poor
chest expansion, reduced breath sounds,
reduced expiratory tidal volume, abnormal
ventilator sound, high airway pressure alarm)
Hypoxia secondary to hypoventilation
Circulatory collapse due to high intrathoracic
pressure (e.g. occluded expiratory limb,
tension pneumothorax)
Tachycardia
Systematic approach to diagnosis of high
airway pressure:
Gas supply
Check O2 bypass/flush/other high pressure gas source
Circuit
Ventilator/bag switch
Obstruction to expiration in circuit, ventilator,
scavenger system
PEEP valve?
Exclude circuit and machine problem by
disconnecting and ventilating with self-inflating bag
Airway
Exclude obstruction: filter, airway, ETT, secretions,
foreign body
Lungs
Bilateral chest expansion? (endobronchial intubation,
pneumothorax, haemothorax)
Breath sounds? (bronchospasm, endobronchial
intubation, aspiration, pulmonary oedema, atelectasis)
Surgical Procedure
Raised intra-abdominal pressure
Surgical intervention
Position
Pleural cavity
pneumothorax, haemothorax
Chest wall
Inadequate muscle relaxation, opioid induced chest
wall rigidity
Malignant hyperpyrexia
Obesity
gas supply
circuit
airway
lungs
pleural cavity
chest wall
surgical procedure
Anaesthetic Emergencies
66
Abnormal ETCO2 in the Anaesthetised Patient
Increased ETCO2 PaCO2=K x CO2 production
Alveolar ventilation
Normal upper limit 46mmHg
Apnoea results in rise of PaCO2 of 8-15mmHg in
first minute, then 3mmHg /min
Causes of hypercapnia
a) Normal lung function:
Exogenous: laparoscopic CO2 insufflation,
NaHCO3 administration, inspired CO2 (soda
lime exhausted, incompetent valves,
rebreathing)
Hypoventilation: respiratory depression,
increased mechanical load due to decreased
compliance or increased resistance in
respiratory system, inadequate IPPV
Increased CO2 production: fever, sepsis,
seizures, hyperthyroidism, TPN.
b) Impaired gas exchange mismatch between
ETCO2 and PaCO2
Increased anatomic dead space, inappropriate
artificial airway.
Increased physiological dead space- reduced
cardiac output, hypovolaemia, hypotension,
pulmonary embolism, COPD
Initial response to a crisis: The anaesthetist’s ABC
Systematic approach to raised ETCO2
Inhaled CO2
Check capnograph trace for return to baseline
Exogenous Insufflation with CO2, NaHCO3
Hypoventilation ventilator settings, airway pressure,
?obstruction, lungs
Increased Production
fever, parenteral nutrition, malignant hyperthermia
Inhaled/exogenous CO2
hypoventilation
increased production
Anaesthetic Emergencies
67
Decreased ETCO2
No ETCO2: consider oesophageal intubation,
accidental extubation.
ETCO2 may not reflect PaCO2 if ventilation is
going to unperfused lung, e.g. severe
hypotension, pulmonary embolism
Erroneously low ETCO2 may be due to air
entrainment in the circuit, equipment
malfunction. Onus of proof is on the anaesthetist
to verify data is erroneous
Systematic approach to diagnosis of decreased
ETCO2:
Airway
Oesophageal intubation, accidental extubation
Circuit
Air entrainment (leak), dilution with circuit gases
(sampling problem)
Ventilation
Ventilator settings, overenthusiastic hand ventilation
Gas Exchange Problem
Pulmonary embolism, cardiac failure/arrest, severe
hypotension
Decreased production
Hypothermia, hypothyroidism, decreased metabolism
airway
circuit
ventilation
gas exchange
decreased production
Anaesthetic Emergencies
44
Hypertension
The hypertensive, anaesthetised patient is
generally responding to a surgical stimulus or has
pre-existing hypertension. Specific
circumstances may suggest a neurological cause.
However, the cause may be a response to hypoxia
or hypercarbia, to unintended exogenous
administration of a vasoconstrictor, or to
phaeochromocytoma. Always include the
surgery in your systematic review. If your initial
response doesn’t work, consider the following
sequence:
Systematic approach to hypertension:
Pre-existing hypertension
Treated, untreated, ?medication taken
Sympathetic reflex response:
Light anaesthesia: is the anaesthetic agent actually
being delivered? (Vaporizer leak, IV infusion
disconnection/ error)
Hypoxia, hypercarbia: check SpO2, ETCO2
Cerebral event: raised ICP, cerebral ischaemia,
vasospasm
Sympathomimetic effect
Exogenous: accidental administration?
Endogenous: e.g. phaeochromocytoma
Surgical: Aortic clamp
Pre-existing hypertension
sympathetic reflex
response
sympathomimetic effect
surgical
Anaesthetic Emergencies
69
Hypotension
Hypotension is a very common unintended event
in anaesthesia practice, most commonly resulting
from relative overdose of anaesthetic agents,
hypovolaemia or central neural blockade. For
severe hypotension, the initial response to a crisis
algorithm would be appropriate. Consider
treatment before or in the process of diagnosis. If
the initial intervention doesn’t solve the problem,
the following approach may be useful:
Systematic approach to hypotension:
Hypovolaemic
Blood loss, fluid deficit
Cardiogenic
Contractility, rate, dysrhythmia
Anaesthetic agent, vasodilators
Distributive
Vasodilation: drugs, sympathetic block, sepsis,
anaphylaxis
Obstructive
High intrathoracic pressure, tamponade, pulmonary
embolus, surgical compression
Hypovolaemic
Cardiogenic
Distributive
Obstructive
Trauma
70
The Management of Trauma
Dr Tim Gray
Dr Richard Morris
The aims of this module are to increase skill
and knowledge in the approach to resuscitation
and management of the trauma patient in the
perioperative period.
Objectives This module serves as an introduction to many
aspects of trauma anaesthesia:
The process of early evaluation and
resuscitation of the trauma patient.
Effectively reviewing the trauma patient
on handover from the resuscitation team.
Evaluating evolving injuries during
anaesthesia care.
Coordinating management priorities and
effective team behaviours.
Responding to specific problems
including:
Cervical spine injuries
Intracranial trauma
Trauma related airway problems
Intra cranial trauma
Concealed bleeding
Large volume resuscitation
Cardiothoracic injuries
Complications of long bone and pelvic
injuries
Trauma
71
Overview
The resuscitation and management of the
multiply injured patient can be divided into
three phases: Initial resuscitation, definitive
management of injuries, ongoing care and
recovery. The boundaries between these
phases may be blurred considerably. Trauma
victims may require anesthesia and surgery
while still in the resuscitation phase, occult or
evolving injuries may cause acute deterioration
during definitive management or subsequent
care. Thus it is imperative that anesthetists
have a systematic approach to assessment and
management of the trauma victim at all stages
of management, as well as strategies to deal
with specific trauma related anesthetic issues.
This module outlines principles well covered
in the EMST [Early Management of Severe
Trauma] course convened by the RACS.
This module does not attempt to replace this
course, completion of which is
recommended for Anaesthetists who are
regularly involved in the management of
injured patients.
Initial Management
The management of the severely injured
patient requires rapid identification of
management priorities based on their injuries,
their vital signs and their mechanism of injury.
A brief review of the steps involved in
reception of severely injured follows:
Triage
This process is a distribution of resources to
achieve the greatest good for the largest
number of casualties. If the resources are
sufficient the patients with life-threatening or
multiple injuries are treated first. However if
the number of casualties exceeds the capacity
of the facility or staff then those casualties
with the greatest chance of survival with the
least expenditure of time, equipment and staff
are managed first.
Pre hospital handover
The value of an accurate description of the
environment and mechanism of injury cannot
be overestimated. A brief summary of the
mechanism of injury as well as pre-hospital
management can provide important
information, but should not take priority over
management of life threatening injuries. Pre-
hospital teams may have a system of handover
of clinically relevant material. If possible try
not to interrupt the paramedic whilst they
handover, but listen and save any relevant
questions for the end.
Assessment
Initial assessment can be divided into three
phases, these are:
Primary Survey
Resuscitation Phase
Secondary Survey
Primary Survey
The primary survey is a rapid initial
assessment the goal of which is to rapidly
identify and manage injuries that pose an
immediate threat to the patient‟s life namely:
Airway obstruction
Chest injuries with compromise of the
breathing or circulation
Severe internal or external haemorrhage
A systematic approach is essential so that
nothing is missed, hence the ABCDE
approach:
A - Airway maintenance with cervical spine
control.
B - Breathing and ventilation.
C - Circulation with haemorrhage control.
D - Disability: neurological status.
E - Exposure of the patient for a full
examination.
Life threatening injuries are identified and
managed simultaneously.
Airway (& Cervical Spine)
Assess the airway – can the patient talk
and breath freely? Is the airway obstructed
or does it need to be protected ?
Avoid the use of nasopharyngeal airways
in the presence of head/facial trauma
It is important to assume that in the
presence of multiple trauma a cervical spine
injury has occurred until ruled out by
appropriate radiology and clinical
examination.
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72
Breathing
If oxygenation / ventilation is inadequate
consider:
Bag / mask ventilation
Decompression of tension pneumothorax
Drainage of haemothorax
Closure of open pneumothorax
Circulation (& haemorrhage control)
Assess circulation. If inadequate then:
Control external haemorrhage
Establish at least two large bore peripheral
IV cannulae ( 14 or 16G )
Cross match 6 units of red cells and
consider need for FFP and platelets
Rapidly administer 2 litres Hartmann‟s
solution and assess response.
In severe injuries, or if the patient must be
transported, consider early placement of an
arterial line.
Consider the early use of O negative blood
clotting factors or activated factor VII
(Novoseven) if available (see below)
Disability
Rapid assessment of level of
consciousness using the AVPU score:
A awake
V responding to verbal commands
P responding to painful stimuli
U unresponsive
Score of P or U corresponds to a GCS of 8
or less and suggests a need for airway
protection.
Assess pupils for symmetry
Exposure
The patient should be completely
undressed and an active search made for
significant injuries.
Despite the need for a full examination it is
important to avoid hypothermia in the
trauma patient. Hypothermia is associated
with poorer outcomes, and after
examination the patient should be covered
by warmed blankets of a forced air
warming device.
Resuscitation
Immediate resuscitation consists of
management of hypovolaemia, oxygenation
and haemorrhage control. During resuscitation
continual re-evaluation of the ABCs is
undertaken. At this stage urinary and
nasogastric catheters can be inserted if
indicated. Further monitoring including blood
pressure, ECG and pulse oximetry will
supplement the vital signs. Xrays of the lateral
cervical spine, AP chest, and AP pelvis are
useful early on, while films of other injuries
can be delayed until after the secondary survey
is complete. Blood is taken for cross match and
investigations.
Secondary Survey
Systematic evaluation of the patient including
history and physical examination
The secondary survey is only undertaken when
the primary survey is completed, resuscitation
is well under way and the patient‟s vital signs
are normalizing. Consequently the secondary
survey may well be delayed for up to several
hours if the patient requires surgery or
intervention to stabilize them.
History
The AMPLE mnemonic suggested in the
EMST course provides a useful summary of
the patient‟s history:
A Allergies
M Current Medications
P Past medical history / Pregnancy
L Last meal
E Events / Environment relating to injury
Physical examination
Head
Scalp
Ocular examination
Ear and tympanic membrane
Periorbital soft tissue injuries
Faciomaxillary injuries
Neck
Assume cervical injury in all patients
Tracheal deviation
Subcutaneous emphysema
Neck veins
Penetrating wounds
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73
Chest
Clavicles, ribs, sternum
Heart and breath sounds
Review chest Xray, preferably with a
trauma surgeon or emergency physician
Abdomen
Bruising, tenderness
Pelvis
Avoid excessive manipulation of pelvic
fracture
Rectal / Vaginal examination
Pregnancy test if appropriate
Consider need for FAST scan
Musculoskeletal
Fractures and distal neurovascular deficits
Peripheral pulses
Spine and back (log-roll )
Wounds and other minor injuries
Neurologic
Assess GCS
Pupils
Spinal cord function
Motor
Sensory / reflexes
The need for further investigations will be
determined as a result of this review. However
they may need to be delayed until initial,
urgent surgical procedures have been
undertaken. Determining the relative priorities
for operative treatment, detailed radiological
investigations, and transfer to other areas for
definitive care requires collaboration and input
from all senior staff managing the patient.
These procedures should not interrupt the
ongoing resuscitation and continuous re-
evaluation of the patient.
Evolving Injuries
The early response to injury is a dynamic
process. Continual review of the patient‟s
general condition is essential. Ongoing
concealed blood loss can occur particularly
with pelvic fractures. Acute brain swelling can
diminish potential for long-term neurological
recovery.
Hand-over of Care
Multiple transfers of management occur for the
trauma patient. In-hospital transfers can
involve both resuscitation teams [emergency
medicine, anaesthetic, intensive care] as well
as subspecialty surgical teams.
During such hand-over the essential elements
of care need to be discussed while the notes
and patient are examined. These are:
History: Allergies, Medications, Past
medical, Last meal, Environment of injury.
Injury catalogue and active problem list.
Treatments already undertaken [especially
fluids administered] and response.
Investigations undertaken and results
available or pending.
Blood products available.
Surgical priorities, planning and
coordination.
An oral summary and completed
documentation are both critical to preventing
further injury to the patient.
Management of Large-volume Resuscitation
Resuscitation end-points
Traditionally, adequacy of fluid resuscitation is
assessed by normalisation of blood pressure,
heart rate and urine output. Suboptimal tissue
perfusion persists, however, in a significant
number of patients with multi-system trauma
after normalization of blood pressure, heart
rate and urine output . A number of alternate
endpoints have been studied, the most practical
being serum lactate, base deficit and gastric
mucosal pH levels. There is evidence to
suggest that normalization of one or all of
these parameters as early as possible within the
first 24 hrs following injury significantly
improves survival in severely injured patients.
Despite this, fluid resuscitation should not in
any circumstances prevent the definitive
treatment of injuries.
Large volume resuscitation in trauma
Patients who are hypovolaemic (more than
50% blood loss) following severe trauma are at
high risk of developing multiple organ system
failure and death The triad of acidosis,
coagulopathy and hypothermia are associated
with significantly increased mortality in this
patient subgroup. Furthermore aggressive
attempts to normalize haemodynamic
parameters prior to control of hemorrhage have
been shown to worsen outcome, particularly in
penetrating trauma to the torso.
Whilst the optimal algorithms for fluid
Trauma
74
resuscitation, blood product replacement, and
the use of inotropes and/or vasopressor are yet
to be determined, evidence suggests that
resuscitation of the shocked trauma patient
should be thought of in two phases.
Initial resuscitation prior to control of
hemorrhage should be limited to keep blood
pressure around 90mmHg. Subsequent
resuscitation focuses on the rapid surgical
control of bleeding, by packing if necessary,
aggressive reversal of acidosis, hypothermia
and coagulopathy – sometimes in the intensive
care unit – followed by delayed definitive
repair of non bleeding injuries.
There is evidence that crystalloid solutions
may potentiate cellular injury caused by
hemorrhagic shock and therefore blood
products should be commenced earlier than
normal.
Fresh frozen plasma (FFP) should be ordered if
the initial request of blood is 6 units or clinical
impression of 50% blood loss. Ketchum
suggests FFP before 1 blood volume is lost.
Platelet requirements are less predictable but
should be given after 10 units packed cells or
earlier.
Hb and clotting should be checked regularly.
Cryoprecipitate and recombinant fVIIa may be
required to correct refractory coagulopathy.
Anecdotal evidence from the military suggests
that early aggressive correction of acidosis and
coagulopathy with minimal use of crystalloid
significantly improves the outcome in
casualties requiring major resuscitation.
Anaesthetic Implications of Airway Trauma
Blunt laryngeal trauma
Mortality rates of all airway injuries vary, but
may range between 15-40%. Death is usually
the result of associated injuries including
aspiration (blood & recurrent laryngeal nerve
injury), intrapulmonary haemorrhage, frank
airway disruption and laryngospasm.
Intubation may cause further trauma and failed
attempts may precipitate complete airway
disruption and/or obstruction.
Diagnosis requires a high index of suspicion.
Patients may be asymptomatic for 24-48 hours,
and may have distracting injuries.
High risk mechanisms include:
Direct anterior neck trauma
Steering wheel or dashboard in MVA
(motor vehicle accidents)
„Clothes-lining‟ injuries in motorcycle or
bicycle accidents
Other direct blows to the neck
Severe Flexion / extension injuries
Crush injuries e.g. attempted hanging
Mechanism may predict site of injury
Direct blow
Laryngeal or cricoid cartilage injury more
likely.
Thyroid cartilage comminuted fractures
causes separation of epiglottis from larynx
Fractures of lateral portion of thyroid
cartilage may cause false passages and
fragments may obstruct intubation attempts.
Extension / flexion injuries
Tracheal tears or laryngotracheal separation
may occur. Most commonly occurs at
cricotracheal junction where connective
tissue is weak.
Airway held in close approximation by
peritracheal tissue & strap muscles during
negative pressure ventilation. Severed ends
may be dislodged on attempts to pass an
ETT.
Major diagnostic criteria suggestive of
significant airway injury include:
Dyspnoea
Subcutaneous emphysema,
Stridor,
Inability to tolerate the supine position.
The presence of major criteria has been
suggested by some as an indication for
immediate surgical tracheostomy under local
anaesthesia
Minor criteria include:
Local swelling & tenderness
Hoarseness,
Dysphagia
Haemoptysis.
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75
Assessment Investigations:
Computed Tomography (CT). Regarded as
investigation of choice by many, assesses
integrity of larynx, condition of
cricoarytenoid joints & endolaryngeal
tissue not seen on fibreoptic endoscopy
however CT is inadvisable in the
presence of a major diagnostic feature.
Laryngoscopy. Direct flexible
nasolaryngoscopy/bronchoscopy is most
well tolerated; it allows evaluation of cord
movement, laryngeal mucosa & airway
lumen with less risk of worsening cervical
spine injury. Bronchoscopy may allow
securing of the airway more distal to the
injury, or endobronchial intubation if
necessary. Use topical local anaesthetic
with caution due to risk of aspiration.
Indirect laryngoscopy may cause coughing /
gagging & further compromise the airway.
Cervical spine and chest X-rays may show
subcutaneous (in particular cervical
emphysema) & extrapleural air
(pneumothorax or pneumomediastinum) &
other associated injuries.
Airway management
Management should be considered case by
case, is dependent likely injury and the skills
of the managing team.
If one or more major diagnostic feature is
present, management should proceed in
theatre with surgical assistance immediately
available Options are:
Endotracheal intubation under general
anaesthesia – use of an ETT at least one
size smaller than usual has been suggested,
uncut.
Inhalational induction avoids use of
positive pressure ventilation but there is the
risk of aspiration in the [non-fasted] trauma
patient. Intravenous induction may be
necessary in the confused / uncooperative
patient.
Awake fibreoptic intubation
Rigid laryngoscopy & bronchoscopy – may
allow intubation distal to the site of injury
NB: Blind nasal intubation & percutaneous
tracheostomy may exacerbate injury & are not
advised.
Be aware:
Cricoid pressure may dislocate fractured
cricoid cartilage or entirely disrupt a partial
tracheal transection.
Positive pressure ventilation can exacerbate
air leaks & worsen air dissecting around
structures / surgical emphysema.
Creation of false passages can occur during
intubation attempts.
Failed attempts at passage of ETT through a
fractured portion may cause complete
dislocation and obstruction
Cricothyroidotomy may be useless in
cricoid cartilage or distal trachea injury.
Airway burns
Most deaths from burns are secondary to
respiratory complications mainly due to
inhalation of toxic products of combustion.
The injury of most concern in the acute
management of trauma is that of thermal injury
to the upper airway resulting in rapidly
progressive oedema and obstruction.
Signs suggestive of inhalational burns:
Major
Hoarse voice
Brassy productive cough
Stridor
Facial, oral pharyngeal burns / oedema of
face & mouth
Minor
Singed nasal hairs
Carbonaceous sputum or oropharyngeal
carbon
Flash burns may cause superficial burns to face
and lips and do not usually cause an upper
airway burn, however the patient should still
be assessed for the above signs.
Management
Major signs are highly suggestive of laryngeal
injury and early intubation must be considered.
Although maximal swelling usually occurs 12-
36 hours after injury, pharyngeal and laryngeal
oedema may develop rapidly (over minutes)
following inhalational burns to cause complete
airway obstruction. Orotracheal intubation may
rapidly become impossible, necessitating a
surgical approach through a now anatomically
distorted airway.
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76
Be Aware:
Inhalational injury may be associated with
carbon monoxide poisoning.
Burns are associated with drug or alcohol
intoxication or psychiatric disturbance.
Subsequent oedema may be extensive so an
uncut endotracheal tube should be used.
Anaesthetic Implications of Chest Trauma
Major chest trauma is usually fatal on scene so
the survivors reaching hospital are a self-
selecting group. Only 15% of them require an
operation. The rest may need volume
replacement, ventilation, chest drains and
analgesia. The chest Xray is an essential and
vital source of information and needs to be
carefully and systematically evaluated.
Major airway injury is suspected when there is
surgical emphysema in the neck, mediastinal
air or pneumopericardium on the CXR. If it is
suspected, attempt to delay intubation and
IPPV until bronchoscoped.
Chest drains should only precede the CXR if
the patient is deteriorating rapidly. Chest tube
insertion should be performed by surgical
incision followed by blunt plural dissection.
Use of the trochar when inserting the tube is
NOT recommended due to the increased
incidence of lung damage with this method.
Keeping the pleural cavity empty will help to
seal off air leaks and stop bleeding.
Thoracotomy is not usually needed unless the
blood loss is more than 1500 mls initially or
more then 200 mls/ hour for two hours.' A
larger volume of blood than this suggests the
injury is not just one or two intercostals vessels
but potentially something more significant.
Cardiac tamponade most commonly results
from cardiac laceration following a penetrating
wound. It is characterised by distended neck
veins (may not be present in a hypovolaemic
patient), hypotension and muffled heart
sounds. The diagnosis may be confirmed on
FAST ultrasound. Pericardiocentisis is of little
use as the blood in the pericardium is usually
clotted and may result in laceration of the
ventricle or coronary arteries. Urgent transfer
to theatre for thoracotomy is the management
of choice.
Emergency department thoracotomy (EDT) is
a drastic procedure with limited utility. It
should be reserved for patients who are in
extremis following penetrating trauma to the
chest where pericardial tamponade is suspected
and appropriate surgical expertise is
immediately available.
Intra-cranial Trauma
About 50% of trauma deaths are associated
with Traumatic Brain Injury (TBI). Early
management of TBI should be direct toward
minimizing progression of injury in the at risk
brain. Specific aims for the anaesthetist are:
Minimise secondary insults.
Detect neurological deterioration during
management of other injuries.
Seek neurosurgical advice to aid effective
decision-making.
Undertake specific neuro-resuscitative
measures when required.
Secondary injury can result from a number of
causes with specific management
requirements:
Hypotension is strongly associated with poor
outcome in TBI. A number of studies suggest
that a single systolic pressure below 90mmHg
is associated with a two to three-fold increases
in.
Hypoxia hyper/hypocapnoea and hyper/
hypoglycemia are also associated with poor
outcome, however the evidence is less
definitive.
Management strategies for TBI
Fluid resuscitation
Given the strong association between
hypotension and poor outcome, the systolic
blood pressure should be maintained above
90mmHg, although different groups
recommend higher pressures.
The theoretical risk of large volumes of fluid
worsening cerebral oedema does not seen to be
supported in clinical practice, although there
may be some benefit in use of hypertonic
saline in TBI. There is insufficient evidence to
support use of one vasoactive agent above
another if fluids alone are insufficient to
maintain arterial pressure.
Trauma
77
Coagulopathy may increase intracranial
bleeding, so should be aggressively managed.
Ventilatory control
Hypoxia, hypo- and hyper capnoea are all
viewed as avoidable secondary insults.
SpO2 should be maintained above 90% and
PaCO2 between 35-40 mmHg.
Patients with GCS of <9, who are unable to
maintain their own airway or respiratory
parameters or who are requiring CT scanning
or other investigation / intervention are
candidates for intubation and controlled
ventilation.
Glycaemic control
Hypoglycemia should be corrected and
hypoglycemia avoided, but optimum targets
are yet to be defined.
Transfer
The presence of a significant TBI will
generally require management in a center with
appropriate expertise. In peripheral centres
management should be directed at stabilization
and early transfer.
Monitoring
During prolonged procedures to treat other
injuries to the trunk or limbs it is important to
monitor for deterioration. This may require
placement of an ICP [intracranial pressure]
monitor by a neurosurgeon.
Specific neuro-resuscitative measures can
temporarily delay the effect of a rising ICP.
Head up positioning [20 degrees] and adequate
muscle relaxation optimise cerebral venous
pressure. Mannitol infusion [0.5 – 1 gram/ kg]
and acute hyperventilation may also be
indicated in some situations to provide a short-
term reduction in ICP. The use of urgent
decompressive craniotomy for raised ICP due
to closed head injury is becoming more
common, and may become the standard of
care.
X-Rays in the Trauma Setting
General
It is regarded as standard practice that three
standard X-rays are taken in the multi-trauma
patient.
1. Lateral cervical spine
2. Chest
3. Pelvis
Although the usefulness of the lateral cervical
spine film has recently been questioned.
These X-rays:
are performed as part of the secondary
survey
should not prevent resuscitation efforts
preferably be done in the „resuscitation‟
area of A&E (radiology departments are
often not equipped for ongoing
resuscitation)
should be referred for specialist radiological
opinion if any doubt remains as to the
presence of pathology
Clearing the cervical spine
The diagnosis of an unstable spinal injury and
its subsequent management can be difficult,
and a missed spine injury can have devastating
long-term consequences. In trauma patients
therefore, spinal column injury must therefore
be presumed until it is excluded.
Clearance of the cervical spine in trauma
patients is one of the most contentious issues in
trauma care and should not be the sole
responsibility of the anaesthetist.
In the acute phase of trauma management, the
focus should be on appropriate spinal
immobilsation, rather than spinal clearance.
Imaging of the spine should not take
precedence over lifesaving therapeutic and
diagnostic procedures. Initially a rigid cervical
immobilisation collar should be used, however
these are likely to cause pressure related
injuries, so should be changed to the more
anatomically correct Philadelphia collar as
soon as possible, preferably within four hours.
The Cervical spine may be clinically cleared in
hospitalized patients if the following conditions
are met:
Normal alertness
No drug or alcohol impairment
No midline cervical tenderness
No focal neurologic deficit
No significant „distracting‟ injury
Pain free range of active movements
If these conditions are not met, then cervical
spine immobilization is indicated until the
neck can be cleared by radiological evaluation.
Guidelines and protocols vary between
institutions depending on expertise and
facilities available, and may include CT scan
and / or MRI.
Practitioners should familiarize themselves
Trauma
78
with guidelines relevant to their own
institution, however general guidelines are
available in the bibliography section
Viewing of X-Rays
There are many different approaches to
viewing X-rays which may be valid.
Experienced clinicians use their own approach.
However the following is just one such
approach.
X-rays should always be examined on a
viewing box or computer screen and the
following features should be sought:
1. Correct orientation of film or view.
2. Name of the Patient
3. Date of the film
These factors, often overlooked in the busy
resuscitation period, are important as often
multiple patients‟ X-rays are viewed at the
same box. Following on from this „The ABC
approach‟ can be used.
1. Adequacy of the X-ray:
Technical factors: adequate penetration of
the film
Patient factors: are all the anatomical
features included.
2. Bones:
Look for any lucency to indicate fractures
by carefully following the outline of each
bone (e.g. rib or vertebrae)
Look for fragments of bone.
Look for alignment of bones (particularly
important in the C-spine)
3. „Cpaces‟ and other soft tissues:
4. Diaphragm and Disc spaces in the CXR and
C-spine respectively.
5. Extras: This refers to additional equipment
often placed in the patient such as
nasogastric and endotracheal tubes.
Lateral Cervical Spine
If there remains any clinical doubt re the
stability of the C-spine expert
radiological/neurosurgical or orthopaedic
advice should be sought. Until such time the
patient should be treated as an „unstable spine‟
with appropriate immobilisation. A normal
lateral C-spine film may also miss up to 15%
of injuries. Children may also sustain
significant cord injury without any bony
injury.
The following features are sought.
1. Adequacy:
The lower part of the skull, all seven
cervical and the first thoracic vertebrae
must be seen.
The x-ray should be of reasonable
penetration such that the bony and soft
tissues are clearly visible. It should be taken
in the neutral plane.
2. Bones:
Correct alignment of the bones is assessed by
tracing four lines:
Anterior vertebral bodies
Anterior spinal canal (or posterior vertebral
bodies)
Posterior spinal canal
Spinous process tips
These lines should trace a gentle continuous
curve and any deviation >3 mm would
indicate a dislocation.
Vertebral bodies: anterior height should not
be <3mm posterior height
The distance between the anterior arch of
C1 and the odontoid peg should be < 3 mm.
3. „Cpaces‟ and soft tissues:
The prevertebral soft tissues should be
<5 mm. Any widening of this „space‟
would tend to indicate a fracture or
dislocation.
The interspinous ligaments should be
inspected for any widening indicating a
dislocation
4. Discs:
Intervertebral discs and facet joints should
be examined
5. Extras:
Look for bony fragments in the spinal
canal.
Check path of nasogastric and endotracheal
tubes.
Chest X-ray
Look for the following features:
1. Adequacy:
Penetration of the film should such that the
disc spaces of the lower vertebrae can be
seen through the cardiac shadow.
The entire chest wall and both costo-
phrenic angles should be visualised.
Rotation of the film can be assessed by
comparing the distance between the
clavicles and the spinous processes‟.
In the trauma setting often an AP rather
than a standard PA film is obtained.
2. Bones:
Initially the humerus, clavicles and scapula
on both sides are inspected.
Thereafter the ribs on each hemi-thorax are
Trauma
79
individually traced looking for fractures.
Fractures of the upper three ribs are
associated with cardiac, aortic and
bronchial injury.
Rib fractures are associated with a
haemothorax and pneumothorax.
Lastly the vertebrae are inspected.
3. Cpaces and soft tissues
The mediastinal structures are examined
from top to bottom
The trachea should be centrally placed.
In a child the thymus may give an
appearance of a widened mediastinum.
The aortic arch should be uniform and
clear.
Widening of the mediastinum may indicate
a traumatic rupture of the aorta.
The cardiac shadow should lie 2/3 in the
left hemi-thorax. AP films tend to
exaggerate the size of the heart.
Displacement of the heart is either due to
the mediastinum being pushed across (e.g.
tension pneumothorax) or being pulled (e.g.
collapse of a lung).
A globular shaped cardiac shadow may
indicate a haemopericardium or pericardial
effusion.
The lung fields should be individually
assessed and then compared to each other.
Lung markings must be seen to the edge of
the lung fields.
The soft tissues surrounding the chest may
contain foreign bodies or subcutaneous air
indicating a pneumothorax.
4. Diaphragm:
The right diaphragm is normally situated
above the left.
Blunting of the costo-phrenic angles may
indicate a haemothorax, pleural effusion or
diaphragm rupture.
The appearance of stomach or small bowel
in the chest indicates diaphragm rupture.
5. Extras:
Endotracheal tube should be placed in the
trachea above the carina.
Nasogastric tubes in the left hemithorax
indicate a ruptured diaphragm.
ECG leads and intercostal drains may be
seen.
Further Reading
General ATLS: Advanced Trauma Life Support Program
for Doctors. American College of Surgeons
Committee on Trauma. (1994)
ABC of Major Trauma. Skinner D, Driscoll P,
(Eds) BMJ Publishing (3rd
ed. 1999).
Textbook of Adult Emergency Medicine. Cameron
P (Ed) Churchill Livingstone (2000).
Websites Liverpool Hospital Trauma Services Department
website - www.swsahs.nsw.gov.au/livtrauma
www.trauma.org
Excellent image bank and range of teaching
resources. Range of guidelines esp clearing the
cervical spine. Good links to other trauma related
websites
www.east.org/tpg
Wide range of trauma practice guidelines
Cervical spine www.trauma.org - Articles /
Hoffman JR, Mower WR, Wolfson AB, Todd KH,
et al. NEJM. Jul 13,2000. 343(2):94-100
Resuscitation Holcomb JB et al. Damage control resuscitation:
Directly addressing the early coagulopathy of
trauma. J Trauma. 2007;62:307–310.
Tisherman SA et al .Clinical Practice Guideline:
Endpoints of resuscitation. J Trauma. 2004;57:898-
912.
Ketchum L, Hess JR, Hiipala S. Indications for
early fresh frozen plasma, cryoprecipitate and
platelet transfusion in trauma. J Trauma.
2006;60:S51–S58
Porter JM, Ivatury RR. In search of optimal
endpoints of resuscitation in Trauma patients: a
review. J Trauma. 1998: 44: 908-914.
Cotton BA.The cellular metabolic and systemic
consequences of aggressive fluid resuscitation
strategies. Shock. 2006; 26: 115-121.
Holcomb JB. Use of recombinant activated factor
VII to treat the acquired coagulopathy of trauma. J
Trauma. 2005;58:1298 –1303
Airway Trauma Hurford WE, Peralta R. Management of tracheal
trauma. Canadian Journal of Anesthesia.
2003;50:R4
Pancholi SS. Laryngeal Fractures.
http://www.emedicine.com/ent/topic488.htm
Ma S, Christey G. Case report Non-operative
management of a blunt hypopharyngeal injury.
Liverpool Hospital Trauma Services Department
website, Available online 18 January 2006.
www.swsahs.nsw.gov.au/livtrauma Miller K, Chang A. Acute inhalation injury. Emerg
Med Clin N Am. 2003;21:533-557.
Garner JP, Jenner J, Parkhouse DAF. Prediction of
upper airway closure in inhalational injury. Military
Medicine. 2005;170: 677-682.
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Thoracic trauma Meredith JW, Hoth JJ. Thoracic trauma: when and
how to intervene. Surg Clin N Am. 2007;7:95–118.
Neurotrauma Moppett IK. Traumatic brain injury: assessment
resuscitation and early mamgement.Br J Anaesth.
2007;99:18-31.