The Royal College The Difficult of Anaesthetists
Airway Society
4th National Audit Project of
The Royal College of
Anaesthetists and The Difficult Airway Society
Major complications
of airway management
in the United Kingdom
Report and findings March 2011
Editors
Dr Tim Cook, Dr Nick Woodall and Dr Chris
Frerk
The National Patient Safety Agency The Intensive
Care The College of Emergency Patient Safety Division Society Medicine
Review Panel
The review panel was composed of
experts interested in airway management, often with a sub-specialty interest.
Nomination was by the supporting organisation, not NAP4. Some panel members
were invited for specific expertise but did not represent organisations.
Dr Ann Black (Association of
Paediatric Anaesthetists)
Professor Jonathan Benger (College
of Emergency Medicine)
Dr David Bogod (Medico-legal expert)
Ms Tracy Coates (National Patient
Safety Agency and Association for Peri-operative Practitioners)
Dr Tim Cook (Royal College of
Anaesthetists, NAP4 co-lead)
Dr Chris Frerk (Difficult Airway
Society)
Dr Les Gemmell (Association of
Anaesthetists of Great Britain and Ireland)
Dr Jane Harper (Intensive Care
Society)
Acknowledgements
Mr David Huggins (College of
Operating Department Practitioners)
Professor Ravi Mahajan (Royal
College of Anaesthetists Council Member)
Mr Sat Parma (Maxillofacial surgeon)
Dr Anil Patel (Airway expert, also
UK representative of European Airway Management Society)
Dr Adrian Pearce (Airway expert)
Dr Mansuhk Popat (Association of
Anaesthetists of Great Britain and Ireland)
Mr Paul Pracey (ENT–UK)
Dr Audrey Quinn (Obstetric
Anaesthetists Association)
Dr Jairaj Rangasami (Difficult
Airway Society)
Ms Joan Russell (National Patient
Safety Agency)
Dr Jan Shaw (Human Factors Advisor)
Dr Nick Woodall (Difficult Airway
Society, NAP4 co-lead)
Mr RichardYoung (Patient Liaison
Group, Royal College of Anaesthetists)
The panel was chaired by
Dr Tim Cook (Project Lead, Royal
College of Anaesthetists)
Dr Nick Woodall (Project Lead,
Difficult Airway Society)
The authors would like to express
their thanks to the network of LRs who were responsible for collecting and
supplying data. Their role was difficult and demanding, this report would not
have been possible without their hard work, persistence and diligence.
In addition to the Royal College of
Anaesthetists and the Difficult Airway Society a number of organisations
contributed to the development of the project in various ways, including being
represented on its Working Group. These include
the Association for
Peri-operative Practitioners, Association of Anaesthetists of Great Britain and
Ireland, Association of Paediatric Anaesthetists of Great Britain and Ireland,
College of Emergency Medicine, College of Operating Department Practitioners,
Intensive Care Society, National Patient Safety Agency, Intensive Care National
Audit and Research Centre, Obstetric Anaesthetists Association and Patient
Liaison Group of the Royal College of Anaesthetists.
The project was also
endorsed/supported by the Chief Medical Officers of England (Sir Liam
Donaldson), Northern Ireland (Dr Michael McBride), Scotland (Dr Harry Burns)
and Wales (Dr Tony Jewell), the Medical Protection Society and Medical Defence
Union.
We are also indebted to the
President, Council and the Head of Professional Standards (Mr Charlie
McLaughlan) at the Royal College of Anaesthetists. We would also like to
acknowledge the advice of Mrs Karen Thomson, Patient Information Advisory Group
at the Department of Health.
Dr Ian Calder performed an essential
role by acting as a moderator outside of the running of the project. He used
his extensive background knowledge and understanding of airway management and
of the project to aid the LRs in discussions about inclusion criteria.
We thank the following statisticians
for advice Rosemary Greenwood and Hazel Taylor (Research Design Service – South
West, Bristol), Gordon Taylor (University of Bath).
We thank the following for the use
of photographs in the report Tim Cook, Mansukh Popat, Jairaj Rangasami, Audrey
Quinn, Nick Woodall, Adrian Pearce, S Chapman, Alma Medical (ramping Chapters
20 and 22, copyrighted) and Jan Shaw.
Dr Fiona Kelly, Dr Clare Hommers, Dr
Rob Jackson and Dr Tim Cook are thanked for permission to use the various
documents and algorithms that form Appendices 1–4.
The production of the report was
principally by Mrs Mandie Kelly, Mrs Edwina Jones and Mr Phillip Fey.
Finally, we are particularly
indebted to Miss Shirani Nadarajah at the Royal College of Anaesthetists for
her major contribution to the prompt collection and accurate collation of
census data and for project administration.
We are grateful to the editor and publisher
of the British Journal of Anaesthesia for allowing us to reproduce
material published in that journal.
The Royal College of Anaesthetists The Difficult
Airway Society The
National Patient Safety Agency The Intensive Care Society The College of
Emergency Medicine Patient Safety Division
4th National Audit Project of
The Royal College of
Anaesthetists and The Difficult Airway Society
Major complications
of airway management
in the United Kingdom
Report and findings March 2011
■■■■■
The Royal College of
anaesTheTisTs
Churchill House 35 Red Lion Square
London WC1R 4SG
020 7092 1500 info@rcoa.ac.uk www.rcoa.ac.uk
Registered Charity No: 1013887 VAT Registration No: GB 927 2364
18 Registered Charity in Scotland No: SCO37737
Design and layout by The Royal
College of Anaesthetists.
© 2011 The Royal College of anaesthetists and the
Difficult airway society.
All rights reserved. No part of this publication may be
reproduced, stored in a retrieval system or transmitted in any form without
permission. Reproduction in whole or part is restricted and requires prior
permission in writing from the Royal College of Anaesthetists on behalf of the
partnership between the Royal College of Anaesthetists, the Difficult Airway
Society and other organisations.
ISBN 978-1-900936-03-3
1
2
Foreword 5
Quotation
6
The role of this report 7 Executive Summary 8
Section 1
Project description and quantitative analysis
Chapter 1 13 Introduction
Chapter 2 16
Evidence-based medicine and airway management: are they incompatible?
Chapter 3 20 Methods of NAP4
Chapter 4 24
Results of the first phase of NAP4: census
Chapter 5 29
Results of the second phase of NAP4: overall results and
anaesthesia
Chapter 6 41
Results of second phase of NAP4: ICU and the emergency
department
Section 2
Clinical reviews 53
Chapter 7 55
Induction and maintenance of anaesthesia
Chapter 8 62
The end of anaesthesia and recovery
Chapter 9 71 Intensive care
Chapter 10 79
Airway management in the emergency department and remote
hospital locations
Chapter 11 86 Supraglottic airway devices
Chapter 12 96 Tracheal intubation
Chapter 13 105
Management of the ‘can’t intubate can’t ventilate’
situation and the emergency surgical airway
Chapter 14 114
Fibreoptic intubation: uses and omissions
Chapter 15 121
Major airway events in patients with a tracheostomy
Chapter 16 129
Training requirements in airway management
Chapter 17 135
Airway assessment and planning
Chapter 18 143
Head and neck pathology
Chapter 19 155
Aspiration of gastric contents and of blood
Chapter 20 165 Obesity
Chapter 21 174 Children
Chapter 22 181 Obstetrics
Chapter 23 187 Organisation and equipment
Chapter 24 193
A commentary on human factors aspects of cases reported
to NAP4
Section 3
Appendices
Appendix 1 204
Example intubation checklist for ICU and emergency
department
Appendix 2 205
Example algorithm for management of tracheostomy
displacement on ICU
Appendix 3 206
Example algorithm for management of tracheal tube
displacement on ICU
Appendix 4 207
Example patient with at-risk airway proforma for ICU
Appendix 5 208 Recommendations at a glance
■■■■■
NAP4 Report and findings of the 4th
National Audit Project of The Royal College of Anaesthetists
3
CONTENTS
4
You will now be familiar, and
probably tired of the constant comparisons between pilots and anaesthetists.
Yet since the death of my late wife in 2005 I’ve met so many of you who in
private conversations have confirmed a number of things which lead me to
believe we’re closer than you think. Like flying, anaesthetics are a usually
routine process, you develop processes that work for you, you know what you are
doing and you achieve success, sometimes despite the system and colleagues
around you. You anaesthetise well because... ‘You’re a good professional
anaesthetist’. When a patient presents some difficulties it presents a
challenge, but one you can overcome, maybe sometimes not at first attempt, but
you’re good at what you do.
And then one day something happens
which reminds you you’re not perfect. You make an honest mistake, perhaps,
probably in the heat of the moment. It shakes you to your core, your
assumptions about yourself are maybe wrong; colleagues are judging you behind
your back.
Life is a hard teacher, first comes
the exam, then the lesson.
The use of simulation is a valuable
tool because it allows us an insight into ourselves when the odds are stacked
against us. Every pilot has screwed up in the simulator, and those events allow
us to develop more resilient and reliable ways of thinking and working so when
things really do turn bad we have a much greater chance of success. But this is
an insight that many of you won’t have experienced. Sitting around a coffee
table anaesthetists will tell me how they wouldn’t have behaved in the way the
anaesthetists did
on my late wife’s case. It’s
incomprehensible. But place those same anaesthetists and colleagues into the
simulator a week later; you’d be surprised how many do follow the same path
when presented with the same stressors and human factors.
In aviation we learned that what we
took to be the ‘right stuff’ was actually out of date, and in fact in a very
complex and fast moving environment was often ‘the wrong stuff’. The days of
the brave lone pilot battling the odds to win through are over, it’s a team
effort that wins the day, and there are plenty of examples of that. Modern
medicine is becoming too complex and too fast paced to ignore the human factors
that can turn a disaster into an heroic save, or vice versa. You can’t ignore
the impact of your own thinking, tuned to normal, routine success, and the
impact of those around you when things turn nasty.
But I have been privileged to meet a
new type of anaesthetist; who recognises that safety and productivity isn’t
just about one person. These anaesthetists recognise it’s also about developing
systems and cognitive strategies; that using techniques such as briefings and
checklists along with ‘standardised processes’ brings greater reliability and
resilience; and that when the chips are down the team around can really help, if
you’ve made it clear through your words and deeds that it is the way you do
business. And this generation is going beyond the frontline, to look at the
tools of the trade. For example, what is the point of a connector that can be
connected to something that it shouldn’t be,
or a drug label very similar to
another yet very different in purpose? Give us the tools that make it easy to
get it right, give us the processes that give safety a better chance, and give
us the training so that we can use these and behave in a way to make a quantum
leap in safe practice.
NAP4 gives us good data on the scale
and nature of the problem, narrative evidence such as Elaine’s and Gordon’s
makes it real, making this new type of anaesthetist the rule not the exception
is up to you.
Mr Martin Bromiley
founder Clinical
human factors group
■■■■■
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
5
foRewoRD
an excerpt from a fatal accident
enquiry in 2010.
The cause of death was barotrauma as
a result of perforation of the right lung as a complication of anaesthetic
administration. The relevant underlying condition was a fracture of the distal
phalanx of the right little finger... The termination of the anaesthetic
procedure thereby allowing Mr X to waken up was a reasonable precaution which
might have prevented his death. There were several opportunities when that
decision could and should have been taken... There was a failure to observe and
follow clear operating instructions for the safe use of the airway exchange
catheter... There was a breakdown of communication among the anaesthetic team
as to the experience of those present in the use of the airway exchange
device... The most striking feature of this Inquiry was that none of the three
experienced anaesthetists
in attendance gave any consideration
to the fundamental option of waking the patient, particularly having regard to
the minor nature of the surgery involved. Anaesthetists need to be actively aware
of that option, particularly, in anaesthesia for elective procedures for minor
or non-essential surgery.
By permission sheriff linda M Ruxton
in fatal accident inquiry 15 into the death of Mr X
7 april 2010
6
naP4 Report and findings of the 4th National Audit Project of The Royal
College of Anaesthetists
■■■■■
QuoTaTion
The NAP4 project has performed for
the first time a prospective study of all major airway events occurring
throughout the four countries of the United Kingdom during anaesthesia, in the
intensive care unit and the emergency department. Its primary role (a
challenging one) was to was to determine, as accurately as possible, the
incidence of complications of airway management in anaesthesia and we believe
we have gone a long way to achieving this.
However we believe that the greatest
value of this project has been the opportunity to learn from review of a large
series of such sentinel events and analysis of emerging themes.
section 1 of the report contains the quantitative aspects of this report.
The rationale and methodology are described in Chapters 1–3 and the results in
Chapters 4–6.
section 2 is a clinical review of the cases reported to the project.
By location
Chapters 7–8 examine the events
during different phases of anaesthesia and Chapters 9–10 report on events
occurring in the intensive care unit and the emergency department.
By technique
Chapters 11–16 report on the
complications reported organised by clinical technique.
specialty areas, training and
organisation
Chapters 17–24 examine areas of
clinical specialty and important overview topics of assessment, human factors,
organisation and training.
Each chapter is presented to offer
maximum information on the topic and the cases reported to the project while
maintaining patient and clinician anonymity. Clinical vignettes are used to
describe cases which are either typical or illustrative. In these, clinical
detail is necessarily presented, but identifying information is removed as much
as possible.
Each clinical chapter is set out as
follows
■ Headline: a summary of the
key contents of the chapter.
■ What we already know: describing,
in a brief literature review, the relevant current knowledge and areas of
particular interest.
■ Case review: presenting an
overview of the cases reported, organised into themes wherever possible. All
reported cases of interest are included here.
■ Numerical analysis: enumerating the
demographics and other quantitative aspects of the cases in the chapter.
■ Discussion: indicating how
the review of cases further informs what is known already about the chapter
topic.
■ Learning points and recommendations: garnered from the case reviewed but informed also by the
literature review.
■ References.
Each chapter stands alone, but there
are many issues which are relevant to several others and these are cross
referenced as necessary.
The learning points sections aim to
indicate where the project has identified new information or reinforced
existing knowledge. The chapter authors and editors have taken as broad a view
as possible in producing these learning points in an attempt to maximise the
value of the report. As such they represent a combination of literature
interpretation, case review and expert opinion.
The report is neither a primer nor
textbook of airway management. It is not positioned either to support or
condemn one particular aspect of airway management. The report does make
recommendations and these recommendations that follow the learning points are
intended to change practice.
Dr Tim Cook, Dr nick woodall
■■■■■
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
7
The Role of This RePoRT
While it is generally accepted that
airway management may sometimes be problematic and that complications occur, it
was not known how frequently these occur or the nature of the events. NAP4 sets
out to address this.
The 4th National Audit Project of
the Royal College of Anaesthetists and the Difficult Airway Society (NAP4) was
designed to answer the questions;
▪
What types of airway device are used
during anaesthesia and how often?
▪
How often do major complications,
leading to serious harm, occur in association with airway management in
anaesthesia, in the intensive care units and in the emergency departments of
the UK?
▪
What is the nature of these events
and what can we learn from them, in order to reduce their frequency and
consequences?
Phase one of the project established that approximately three
million patients are anaesthetised in the UK each year in the NHS and
delineated the airway devices used to manage these.
Phase two sought to identify all
cases of major complications of airway management in the same population as in
phase one, but also in ICUs and emergency departments. Each reported case was
reviewed by an expert panel to ensure the correct cases were included and to
maximise the amount that could be learnt. In total 186 cases met inclusion
criteria and were reviewed in detail.
We acknowledge that it is very likely that not all relevant
cases were reported to the project and this is discussed in detail in Chapter
5. We estimate that the project might have detected as few as one in four
relevant cases.
Major findings
This report is an in-depth analysis of the reviewed cases. Each
chapter includes a final section enumerating learning points and
recommendations. The recommendations
are extensive in number and breadth,
reflecting the unique opportunity this project offers to examine airway
management in the UK.
This summary does not reproduce or cover all findings in
the
report but highlights the major themes running through the report. Those with a
responsibility for organising airway management policy and for carrying out
airway management are encouraged to read the relevant parts of the report in
full, including detailed recommendations. The recommendations are reproduced in
a single document in Appendix 5.
■ Approximately 2.9 million general anaesthetics are administered
in the United Kingdom National Health Service each year. In approximately 56%
of these cases the airway management is with a supraglottic airway device
(SAD), 38% with a tracheal tube and 5% with a face mask.
Clinical themes
■ Poor airway assessment contributed to
poor airway outcomes. This was due to omission, incomplete assessment or a
failure to alter the airway management technique in response to findings at
assessment. Assessment to predict both potential airway difficulty and
aspiration risk were equally important.
■ Poor planning contributed to poor airway outcomes. when potential difficulty with airway management
is identified a
strategy is required. An airway plan suggests a single
approach to management of the airway. A strategy is a co-ordinated, logical
sequence
of plans, which aim to achieve good gas exchange and prevention of
aspiration. Anaesthetists should approach airway management with strategies
rather than plans.
■ failure to plan for failure. In some
circumstances when airway management was unexpectedly difficult the response
was unstructured. In these cases outcome was generally poor. All anaesthetic
departments should have an explicit policy for management of difficult or
failed intubation and for impossible mask ventilation (e.g. formal adoption of
the Difficult Airway Society guidelines as departmental policy) and for other
airway emergencies. Individual anaesthetists should use such strategies in
their daily practice.
■ The project identified numerous cases where awake fibreoptic intubation (afoi) was indicated but was not
used. The project methods did not enable us to determine why
AFOI was not used but there were
cases suggesting, lack of skills, lack of
confidence, poor judgement and in some cases lack of suitable equipment being
immediately available. This latter problem was prevalent on ICU. Awake
intubation should be used whenever it is indicated. This requires that
anaesthetic departments and individual anaesthetists ensure such a service is
readily available.
■ Problems arose when difficult
intubation was managed by multiple repeat attempts at intubation. The airway problem regularly deteriorated to a
‘can’t intubate can’t ventilate’ situation (CICV). It is well recognised a
change of approach is required rather than repeated use of a technique that has
already failed.
8
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
■■■■■
eXeCuTive suMMaRy
▪
Events were reported where supraglottic airway devices were used inappropriately. Patients who were markedly obese, often managed by junior
trainees, were prominent in the group of patients who sustained non-aspiration
events. Numerous cases of aspiration occurred during use of a first generation
SAD in patients who had multiple risk factors for aspiration and in several in
whom the aspiration risk was so high that rapid sequence induction, should have
been used.
▪
saDs were used to avoid
tracheal intubation in some patients with a recognised difficult intubation. There was often no evidence of a back-up plan. Under these
circumstances if the airway is lost (e.g. due to oedema or mechanical
displacement) this becomes an anaesthetic emergency. Awake fibreoptic
intubation or fibreoptic intubation through a SAD before surgery may offer
a lower risk alternative to SAD use
in cases of known difficulty with tracheal intubation.
▪
Anaesthesia for head and neck surgery featured
frequently in cases reported to NAP4. These cases require careful assessment
and co-ordinated planning by skilled anaesthetists and surgeons. Excellent
teamwork is required as when any part of this process fails the risk of adverse
outcomes is high.
▪
Management of the obstructed airway requires
particular skill and co-operation between anaesthetist and surgeon. This is
best performed in a fully equipped environment with full surgical, anaesthetic
and nursing support. An operating theatre is the ideal location. Tracheostomy
under local anaesthesia may offer a safer alternative to tracheal intubation
after induction of anaesthesia, and it should be actively considered. When
surgical airway performed by a surgeon is the back-up plan, preparation should
be made so this is instantly available.
▪
The proportion of obese patients in case reports
submitted to NAP4 was twice that in the general population, this finding was
even more evident in the morbidly obese. Too often obesity was not identified
as a risk factor for airway difficulty and the anaesthetic technique was not
modified. Particular complications in obese patient included an increased
frequency of aspiration and other complications during the use
of SADs, difficulty at tracheal
intubation and airway obstruction during emergence or recovery. When rescue
techniques were necessary in obese patient they failed more often than in the
non-obese. Obesity needs to be recognised as a risk factor for airway
difficulty and plans modified accordingly.
■ There was a high failure rate of
emergency cannula cricothyroidotomy, approximately
60%. There were numerous mechanisms of failure and the root cause was not
determined; equipment, training, insertion technique and ventilation technique
all led to failure.
In contrast a surgical technique for emergency surgical
airway was almost universally successful. The technique of cannula
cricothyroidotomy needs to be taught
and performed to the highest
standards to maximise the chances of success, but the possibility that it is
intrinsically inferior to a surgical technique should also be considered.
Anaesthetists should be trained to perform a surgical airway.
■ aspiration was the single commonest cause of death in
anaesthesia events. Poor judgement was the likely root
cause in many cases which included elements
of poor assessment of risk (patient
and operation)
and failure to use airway devices or
techniques that would offer increased protection against aspiration. Several
major events occurred when there were clear indications for a rapid sequence
induction but this was not performed.
■ failure to correctly interpret a capnograph trace led to several
oesophageal intubations going unrecognised
in anaesthesia. A flat capnograph trace indicates lack of ventilation of the
lungs: the tube is either not in the trachea or the airway is completely
obstructed. Active efforts should be taken to positively exclude these
diagnoses.
This applies equally in cardiac
arrest as CPR leads to an attenuated but visible expired carbon dioxide trace.
■ one third of events occurred during emergence or recovery and obstruction was the common cause in these events.
Post-obstructive pulmonary oedema
was described in one in ten reports. This
phase of anaesthesia, particularly when the airway was difficult at intubation
or there is blood in the airway, needs to be recognised as a period of
increased risk and planned for.
■ The commonest cause of the events reported to NAP4, as
identified by both reporters and reviewers, appeared to be poor judgement. While this
assessment is made with hindsight it was a consistent finding. The next most
common contributory factor was education and training. Choosing the safest
technique for airway management may not necessarily be the anaesthetist’s most
familiar. It may be necessary to seek the assistance of colleagues with
specific skills, for example in regional anaesthesia or airway management.
■■■■■
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
9
eXeCuTive suMMaRy
■ In more than a third of events from all sources; during
anaesthesia, in ICU and the emergency department, airway management was judged
to be poor. More often there were elements of both good and poor management. In
approximately one fifth of cases airway management was judged to be exclusively
good.
iCu and the emergency department
▪
at least one in four major
airway events reported to naP4 was from iCu or the emergency department. The outcome of these events was more likely to lead to
permanent harm or death than events in anaesthesia. Analysis of the cases
identified gaps in care that included: poor identification of at-risk patients,
poor
or incomplete planning, inadequate provision of
skilled staff
and equipment to manage these events successfully, delayed recognition of
events and failed rescue due to lack of or failure of interpretation of
capnography. The project findings suggest avoidable deaths due to airway
complications occur in ICU and the emergency department.
▪
failure to use capnography in
ventilated patients likely contributed to more than 70% of iCu related deaths. Increasing use of capnography on ICU is the single change with
the greatest potential to prevent deaths such as those reported to NAP4.
▪
Displaced tracheostomy, and to a lesser extent displaced tracheal tubes, were the
greatest cause of major morbidity and mortality in ICU. Obese patients were at
particular risk of such events and adverse outcome from them. All patients on
ICU should have an emergency re-intubation plan.
▪
Most events in the emergency
department were complications of rapid sequence induction. This was also an area of concern in ICU. RSI outside the
operating theatre requires the same level of equipment and support as is needed
during anaesthesia. This includes capnography and access for equipment needed
to manage routine and difficult airway problems.
Airway management is a fundamental
anaesthetic responsibility and skill; anaesthetic departments should provide
leadership in developing strategies to deal with difficult airways throughout
the entire organisation.
Interpretation of results
Many of the events and deaths
reported to NAP4 were likely to have been avoidable. Despite this finding,
the
incidence of serious complications associated with anaesthesia is low. This is
also true for airway management in ICU and the emergency department, though it
is
likely that a disproportionate
number of airway events occur in these locations. The aim of this report is
that detailed attention to its contents and compliance with the recommendations
will make airway management safer.
Many of the findings of NAP4 are
neither surprising nor new, but the breadth of the project, covering the
whole
of the UK for a full year, will hopefully provide impetus
to changes that
can further improve the safety of airway management in the UK in anaesthesia,
intensive care and the emergency department. Our goal should be to reduce
serious complications of airway management to zero.
Dr Tim Cook, Dr nick woodall, Dr
Chris frerk
10
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
■■■■■
eXeCuTive suMMaRy
naP4
MAJOR COMPLICATIONS OF AIRWAY MANAGEMENT IN THE UNITED KINGDOM
Section 1
Project description and quantitative analysis
12
Dr Tim Cook
‘There is one skill above all else
that an anaesthetist is expected to exhibit and that is to maintain the airway
impeccably’
M Rosen, IP Latto 1984
‘The most compelling educational
effort for the anaesthesia community should be to reduce the frequency and
severity of complications related to managing the airway’
Jonathan
Benumof 1995
The two quotations above remind us
that anaesthetists are almost defined by their ability to manage the airway.
Most of the time this is a routine and highly successful procedure but it can
never be assumed to be so.
The 4th National Audit Project of
the Royal College of Anaesthetists (NAP4) examines a large cohort of major
airway complications (leading to death, brain damage, emergency surgical airway
or unexpected ICU admission) in the specialties of anaesthesia, intensive care
medicine and emergency medicine. This introduction offers some context as to
why this is necessary.
Anaesthetists (and other experts managing
the airway) are used to high levels of success. Routine airway management does
not usually fail. However, all modes of airway management employed by
anaesthetists may fail and it
is when they do that anaesthetists
metaphorically ‘earn their corn’. Broadly speaking there are only four modes of
managing the airway: face mask, supraglottic airway (SAD), tracheal tube and
direct access to the trachea.
Face mask ventilation fails in about
1 in 1,500 cases.1,2 Tracheal intubation fails in
around 1 in 1–2,000 routine cases,3,4 laryngeal mask
placement in around 1 in 50 cases5 and the situation
of both intubation and ventilation failure (‘Can’t Intubate Can’t Ventilate’ –
CICV) is unexpectedly impossible in about 1 in 5,000 to 10,000 cases.2,6 However the consequences of these infrequent problems are
potentially catastrophic. CICV accounts for over 25% of all anaesthesia-related
deaths.6
In emergencies all these failure
rates increase several-fold. Importantly other complications of airway
management also undoubtedly increase in cases of predicted difficulty and
during emergency care. Failed tracheal intubation in emergencies
is reported between 1 in 300 and 1
in 800.3,7,8 CICV in the emergency department may occur as often as 1 in 200.9
When failure occurs other
complications become more likely. These include:
■ hypoxia (and its consequences – brain damage, cardiac events,
death)
■ hypoventilation
■ oesophageal intubation
■
aspiration
■
airway trauma (both major life-threatening and minor) ■ awareness.
It is also important not to dismiss
complications arising from ‘easy’ and elective cases as the evidence suggests
that many of these complications may occur even when airway management is
apparently successful and uneventful.
When things do go wrong with airway management
the consequences are significant. Most importantly there is a significant risk
of patient harm and as the patient is likely
to have ‘presented for surgery’
rather than ‘for anaesthesia’ these complications are of particular concern as
they occur during a process that facilitates treatment rather than being the
treatment itself. Such complications are also likely to figure prominently in
adverse publicity and in litigation.
Detailed evidence on the
epidemiology of complications is limited. Critical incident registries are
poorly complied with by doctors and tend to attract reports of mostly low
severity incidents. At present the best evidence has historically come from
litigation-based studies. These analyses are valuable but have several limitations:
as they are incomplete (often not including all insurers), delayed (often up to
a decade), lack denominators, focus only on those cases that lead to litigation
(and which lawyers are interested in pursuing) as opposed to all major
complications and are prone to expert analyst bias. Most importantly the
relationship between complications and litigation is complex10 and it cannot be assumed that the patterns seen in litigation
analyses reflect complications. Despite this they currently offer us the best information
available.
■■■■■
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
13
CHAPTER 1 Introduction
In the American Society of
Anesthesiologists Closed Claims Project (ASACCP) analysis, respiratory cases (which
include airway events) represent about 20% of the total.11,12 These claims are more likely than non-respiratory claims to lead
to death/brain damage (78% vs 29%), be assessed as ‘preventable’ (50% vs 9%)
and involve ‘substandard care’ (64% vs 28%) and a higher proportion were
settled by payment (69% vs 48%). Costs associated with these claims were also
substantially higher.
Inadequate ventilation, oesophageal
intubation and difficult intubation are the ‘big three’ accounting for around
up to 60% of all respiratory claims, with approximately 5% being related to
pulmonary aspiration. In 2005 a review of 179 ‘Difficult airway claims’ found
more than 50% of claims described death or brain damage and care was judged as
‘less than appropriate’ in 50%. Claims were not restricted
to the elderly and infirm, with
claimants having a median age of 40, 43% ASA 1–2 and 75% related to anaesthesia
for elective surgery. Almost 50% of claims were in patients in whom airway
difficulty was predicted: many of whom still had a ‘standard anaesthetic’.
Two-thirds of anaesthesia claims occurred at induction while cases occurring
after induction had a poorer outcome.
Oesophageal intubation and major
airway trauma are
of interest. Oesophageal intubation was often only recognised
by late cardiovascular changes.12 Lung auscultation was often
unreliable. Outcome was mostly poor, with the percentage of cases paid out and
the costs both being high. In recent years capnography reduced the incidence,
but has not eliminated it. The vast majority of lower airway and oesophageal
injuries were associated with difficult intubation: these may present late and
have mortality rates of up to 20%.13 In contrast
laryngeal injuries which comprised 33% of all airway trauma claims occurred
after routine intubation in 80% of cases.14
When major complications occurred
many cases progressed from intubation difficulty to CICV, emphasising the
importance of emergency surgical airway as a rescue technique. However, there
was evidence of delay in performing surgical airway often until the patient was
beyond rescue or in fact dead.
Another important study examining
complications of airway management by Mort14 examined over
10,000 emergency tracheal intubations in one institution over a period of
10
years. He found multiple attempts at laryngoscopy
to be highly associated with marked
increases in rates
of complications. Compared to intubation which was achieved
on first or second laryngoscopy those requiring >2 laryngoscopies led to a
seven-fold increase in hypoxia (14-fold severe hypoxia), six-fold increase in
oesophageal intubation, seven-fold increase in regurgitation, four-fold
increase in aspiration and seven-fold increase in cardiac
arrest. The absolute rates of
complications are notably high: after >2 attempts at intubation the rates of
complications were 70% hypoxia (28% severe hypoxia), 52% oesophageal
intubation, 22% regurgitation, 13% aspiration, 11% cardiac arrest. The closed
claims reports contain similar indicators of increased problems with repeated
attempts at tracheal intubation and also reported that those cases occurring
outside theatre fared less well with 100% suffering brain damage or death.13 While it is clear that it is the most difficult cases that
require most attempts to achieve intubation we can infer that if intubation
attempts are failing something else should be tried. Put simply: if it’s not
working, stop trying it and do something different! The widely promulgated
Difficult Airway Society guidelines strongly emphasise exactly this message.15
Intensive care
Airway management is similarly
important in ICU with
the vast majority of critically ill patients requiring
tracheal intubation. Limited physiological reserve and aspects of the logistics
of ICU make this potentially hazardous. This has become an area of increasing
interest in the last few years. Issues of staffing, tracheostomy management and
use of capnography have all come under the microscope. The limited data
available documenting complications of tracheal intubation in critically ill
patients, is depressing. In 1995 Schwartz reported 297 emergency intubations
with an 11% initial failure rate, 8% oesophageal intubation rate, 4%
aspirations and 3% deaths.16 In 2006 Jaber and colleagues
reported the results of a multi-centre study of 253 ICU intubations.17,18 There was a 28% incidence of serious life- threatening
complications, including severe hypotension (26%), severe hypoxaemia (25%),
cardiac arrest (1.6%), and death (0.8%). Complications were independently
increased when acute respiratory failure or shock were indications
for
intubation. The presence of two operators reduced complications. Both Schwartz
and Jaber reported multiple attempts at intubation in more than 10% of
patients. Whether such results are replicated in different countries with
differing healthcare systems is unknown.
Emergency department
Due to the nature of patients
attending UK emergency departments (severe trauma, critical airways etc) airway
management is routinely necessary. There is increasing involvement of emergency
physicians in delivery of
this care and this is an evolving
process. Regardless of which specialty undertakes airway management
it is
acknowledged that failure and complications are more frequent than under the
controlled conditions in the operating theatre. Rates of difficult intubation
as high as 9% and of emergency surgical airway of up to 0.5% are reported.19–21
14
naP4 Report and findings of the 4th National Audit Project of The
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■■■■■
CHAPTER 1 Introduction
The need for NAP4
There is no closed-claims system in
the UK and while a recent publication explored the very limited data available
on airway-related litigation (finding results that closely mirror those of the
ASACCP) the analysis suffered from at least the same limitation as the ASACCP.
There remains more that is unknown than known.10 Based on
its methodology NAP4 should overcome many of the limitations of clinical
incident and litigation-based analyses: it focuses on major complications, is
prospective and has studied a large and inclusive population over a prolonged
period of time. It
is hoped the report will be of interest to anaesthetists,
intensivists, emergency physicians and many others.
References
.
1 Langeron O et al. Prediction of difficult mask
ventilation. Anesthesiology 2000;92:1229–1236.
.
2 Kheterpal S et al. Prediction and Outcomes of
Impossible MaskVentilation. Anesthesiology2009;110:891–897.
.
3 Rose DK, Cohen MM. The incidence of airway problems
depends on the definition used. Can J Anaes 1996;43:30–34.
.
4 Samsoon GLT, Young JRB. Difficult tracheal
intubation: a retrospective study. Anaesthesia 1987;42:487–490.
.
5 Cook TM, Lee G, Nolan JP. The ProSeal laryngeal
mask airway: a review of the literature. Can J Anaesth 2005;52:739–760.
.
6 Nagaro T et al. Survey of patients whose lungs
could not
be ventilated and whose trachea could not be intubated in university
hospitals in Japan. J Anesthesia 2003;17:232–240.
.
7 Hawthorne L, Wilson R, Lyons G, Dresner M. Failed
intubation revisited: 17 year experience in a teaching maternity unit. Br J
Anaesth 1996;76:680–684.
.
8 Rocke DA et al. Relative risk analysis of factors
associated with difficult intubation in obstetric anesthesia. Anesthesiology
1992;77:67–73.
.
9 Sakles JC et al. Airway management in the
emergency department: A one-year study of 610 tracheal intubations. Ann
Emerg Med 1998;31:325–332.
.
10 Cook TM, Scott S, Mihai R. Litigation following
airway and respiratory-related anaesthetic morbidity and mortality: an analysis
of claims against the NHS in England 1995–2007. Anaesthesia 2010;65:556–63.
.
11 Caplan RA et al. Adverse respiratory events in
anesthesia: a closed claims analysis. Anesthesiology 1990;72:828–833.
.
12 Peterson GN et al. Management of the Difficult
Airway. Anesthesiology 2005;103:33–39.
.
13 Domino KB. Closed Malpractice Claims for Airway
Trauma During Anesthesia. ASA Newsletter 1998;62:10–11.
.
14 Mort TC. Emergency tracheal intubation: complications
associated with repeated laryngoscopic attempts. Anesth Analg 2004;99:607–613.
.
15 Henderson J et al. Difficult airway Society
Guidelines. Anaesthesia 2004;9:675–694.
.
16 Schwartz DE, Matthay MA, Cohen NH. Death and
other complications of emergency airway management in critically ill patients:
a prospective investigation of 297 tracheal intubations. Anaesthesiology 1995;82:367–376.
.
17 Jaber S, Amraoui J, Lefrant JY. Clinical
practice and risk factors for immediate complications of endotracheal
intubation in intensive care unit: A prospective multiple-center study. Crit
Care Med 2006;34:2355–2361.
.
18 Leibowitz AB. Tracheal intubation in the
intensive care: extremely hazardous even in the best of hands. Crit Care Med
2006;34:2497–2498.
.
19 Sakles JC et al. Airway management in the
emergency department: a one-year study of 610 tracheal intubations. Ann
Emerg Med 1998;31:325–332.
.
20 Bair AE et al. The failed intubation attempt in
the emergency department: analysis of prevalence, rescue techniques, and
personnel. J Emerg Med 2002;23:131–140.
.
21 Graham CA et al. Rapid sequence intubation in
Scottish urban emergency departments. Emerg Med J 2003;20:3–5.
■■■■■
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
15
CHAPTER 1 Introduction
Dr Tim Cook Dr David Bogod
The chapters that follow describe
the methods, results and implications of NAP4. The project is based on review
of the reports of a series of 184 major airway-related events occurring in the
UK over a period of a year. From this the project team has identified themes
and, combining this with previous knowledge, extracted lessons that might be
learnt before outlining a series of recommendations that may guide improvement
in care. It is certain that not all cases were reported, and even in the area
of anaesthesia, where the project had the best coverage of hospitals in terms
of LRs, we anticipate that up to three-quarters of cases may not have been
reported.
Viewed in a pessimistic light, NAP4
is a collection of case reports, albeit a large one. It is far removed from the
higher levels of evidence-based medicine.1,2 The cohorts which
the project team have examined are from disparate areas both geographically and
clinically. In terms of evidence level (which ranges from 1++ to 4) the
evidence acquired from the NAP4 database and its review would be assessed as
level 3, which is actually seventh in a ranking of eight levels (Table 1). Our
recommendations which
are based on extensive, structured
review of all cases are consensus-based expert opinion: the lowest quality
(grade D) recommendations (Table 2).
Of course this is true of many
reports and much of medical practice is based on equally low levels of
evidence. As a relevant example the Difficult Airway Society guidelines,3 much quoted, much referred to and widely reflected on
in this report are based on a
similar level of evidence.
The original paper states: ‘Controlled studies
cannot
be performed in unanticipated difficult intubation.
The evidence basis
of these guidelines best fits the description of expert committee reports,
opinions and experience, and is defined as category IV evidence. All DAS
recommendations are supported by at least two case reports or series, the
strongest evidence available for infrequent emergency situations.’
There are many current debates in
airway management.
■ Is it important that a predicted difficult airway should be
managed awake?
Table 1 levels of evidence
|
1 ++ High
quality meta-analyses, systematic reviews of RCTs, or RCTs with a very
low-risk of bias
|
|
1+
Well-conducted meta-analyses, systematic reviews, or RCTs with a low-risk of
bias
|
|
1-
Meta-analyses, systematic reviews, or RCTs with a high- risk of bias
|
|
2++ High
quality systematic reviews of case control or cohort or studies
High quality
case control or cohort studies with a very low-risk of confounding or bias
and a high probability that the relationship is causal
|
|
2+
Well-conducted case control or cohort studies with a low-risk of confounding
or bias and a moderate probability that the relationship is causal
|
|
3 Case control
or cohort studies with a high-risk of confounding or bias and a significant
risk that the relationship is not causal
|
|
4 Non-analytic
studies, e.g. case reports, case series
|
|
5 Expert
opinion
|
Table 2 grades of recommendations
|
A At least one
meta-analysis, systematic review, or RCT rated as 1++, and directly
applicable to the target population; or
A body of evidence consisting
principally of studies rated as 1+, directly applicable to the target
population, and demonstrating overall consistency of results
|
|
B A body of
evidence including studies rated as 2++, directly applicable to the target
population, and demonstrating overall consistency of results; or Extrapolated
evidence from studies rated as 1++ or 1+
|
|
C A body of
evidence including studies rated as 2+, directly applicable to the target
population and demonstrating overall consistency of results; or
Extrapolated
evidence from studies rated as 2++
|
|
D Evidence
level 3 or 4; or
Extrapolated evidence from studies rated as 2+
|
16
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
■■■■■
CHAPTER 2
Evidence-based medicine and
airway management: are they incompatible?
▪
Is it right to administer
neuromuscular blocking agents before confirmation of the ability to ventilate
the patient’s lungs?
▪
Does rapid sequence induction
increase or decrease safety overall?
▪
What is the best way to manage the
obstructed airway?
▪
Is small bore cannula, large bore
cannula or surgical airway the best route for accessing the trachea in an
emergency?
▪
and many more...
It is possible to find considerable
literature on all these topics4–11 but in essence it is
opinion-based, often supported by some (partially) related data, but also with
arguments frequently extrapolated from evidence that is only
partially
relevant.
New equipment is one obvious area where airway management is
bedevilled by lack of evidence. There are certain aspects of the medical
equipment industry, and
its regulation, that mean evaluation is based on
shifting sands.12,13 The rate of new equipment
development
(and modification) also makes it difficult for research to keep
pace, but the reality is that the majority of airway equipment in current use
has been incompletely evaluated by the profession that uses it. Evaluation can
assess two important aspects: efficacy and safety. Relatively small studies can
examine efficacy during routine use (e.g. two supraglottic airway devices, SAD
A vs SAD B for ASA 1 arthroscopy). However, the more difficult and perhaps more
important questions relating to safety and crisis management remain unanswered.
▪
Which is the SAD to use during
advanced indications such as laparoscopy, obesity, lithotomy and ventilation?
▪
Is there a safe weight limit for use
of a SAD?
▪
Can some SADs be safely used to
manage low-risk
emergencies?
▪
Which SAD is most likely to protect
the patient if regurgitation occurs?
▪
Which SAD is most likely to rescue the
airway successfully and safely during CICV?
▪
Which bougie is safest and most
effective in an emergency?
▪
Which are the best new
videolaryngoscopes and how often can they rescue a difficult intubation??
▪
Which supraglottic airway is best
for use as a conduit for fibreoptic guided rescue intubation?
▪
Does an airway exchange catheter
provide safety for difficult extubation?
▪
Which cricothyroidotomy catheter
should we choose?
Some of these questions have been
touched on in small studies and discussed in editorials, but to the best of the
authors’ knowledge they remain unaddressed at any reasonable level of
scientific evidence.12-20
In routine airway management (e.g.
SAD use in low-risk cases, routine intubation with a number of different
laryngoscopes, low-risk rescue intubation techniques performed in healthy
patients) it is arguable that the failure to answer many questions is a failing
of the anaesthetic community. With three million general anaesthetics performed
in the UK each year, study of even a small fraction of these cases could answer
some very weighty questions. The problem, however, is not all the profession’s
fault, the increasingly Byzantine processes for conducting research and the
ever increasing barriers to publishing simple, low-risk research will put off
most clinicians. The poor support which anaesthesia receives from funding
organisations, perhaps because it is considered low-risk, means that we are
victims of our own success. There are solutions to these barriers and perhaps
in the next few years developments, such as the National Institute of Academic
Anaesthesia, will lead to a sensible reconfiguration of the research ratchet.21
Studies examining safety, rather
than efficacy, in airway management are much more difficult to design and this
is particularly so if the aim is to study serious adverse outcomes.
■ Anaesthesia is safe; major adverse events occur infrequently so
massive studies are needed to detect differences between devices or techniques.
■ Different major complications occur in differing settings and
may not all be examined in the same study.
■ Most efficacy studies specifically recruit low-risk patients to
avoid the risk of patient complications and other adverse events (and are
encouraged so to do by ethics committees); this does not suit a safety based
study.
■ It may be considered by some, including ethics committees,
unethical to seek out patients at high-risk of complications, even when
clinical equipoise exists.
■ Even if such studies are approved they need to run for extended
periods of time and in multiple sites to identify and recruit sufficient
patient numbers.
■ Funding for such studies is difficult to acquire.
■■■■■
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
17
CHAPTER 2
Evidence-based medicine and
airway management: are they incompatible?
Randomised controlled trials, RCTs,
(the benchmark of high quality research) are often not a suitable methodology
for such studies. This is particularly so when the researchers wish to study
emergency airway management (e.g. what
is the best anaesthetic induction
technique to use for management of a high-risk obstructed airway or which
equipment is most efficient for safely rescuing a high-risk lost airway).
Specifically, impediments to performing high quality studies in emergency
airway management include:
▪
major events are infrequent
▪
these events are unpredictable
▪
Where events are predictable,
considerable effort is usually made to use alternative techniques so that the
event does not occur
▪
when events do occur they do so most
frequently in patients who are already anaesthetised and therefore unable to
consent to take part in research
▪
if events occur or are predicted in
those who are not anaesthetised, the clinical setting means the patient is
often not in a position to give informed consent
▪
clinicians who attend these
emergencies need to act swiftly and decisively to minimise harm and likely have
little or no time to consider the possibility of performing research
▪
success of any technique is very
much based on user experience and preference.22
Perhaps the most important issue is
that each event that leads to a major complication is a unique situation framed
by a combination of patient history, location, personnel, available equipment,
available skills, pathophysiology, urgency and surgical and anaesthetic
requirements. Research drawn from a small number of similar cases may therefore
not be widely generalisable.
However, the research questions that remain unanswered are nevertheless
important. Anaesthetic and surgical interventions are relatively unusual in
that they involve the physician performing an act that is predictably dangerous
for the patient (in anaesthesia this involves intentionally causing
unconsciousness, respiratory arrest and inevitable airway obstruction) and then
using interventions to prevent complications of these actions. Complications
are therefore ‘active complications’
(i.e. complications of commission) rather than ‘passive’ ones (complications of
omission). When complications arise in these circumstances they are often
considered to represent failure perhaps by peers but certainly by the press and
even during litigation. Compare a death from hypoxia due to failure to manage
the airway after induction of
anaesthesia, with a death from myocardial infarction due to failure to
appropriately manage hypercholesterolaemia in general practice. It is likely
there are more of the latter, but individual cases of the latter gain
little adverse publicity or litigation,
and the former group gain only a small slice of the research funding pie.
Study methodologies other than the
RCT (prospective cohort studies, with or without prospective or historical
cohort controls, critical incident database analysis and prospective
complication registries – as in NAP4) may be the only methods of studying a
large enough number of events to identify sufficient cases for conclusions to
be drawn. However, most databases do not contain enough clinical data to
extract useful learning.
Studies that involve expert review
and recommendations are rightly subject to criticism. Experts may differ in
their opinion,23,24 be affected by hindsight
bias,25 change their opinion according to patient outcome,26 have a tendency to agree with peers when placed in a group27 and of course they may simply be wrong.
NAP4 has managed to gain approval
and involvement
from every NHS hospital in the four countries of the UK.
Considerable efforts have been made to collect the highest quality data and to
focus on those complications that are likely to be important to patients,
clinicians and institutions. NAP4 review processes tried to take account of all
the pitfalls described above: see Chapter 3.
So NAP4 draws on information about
relevant complications, derived from a cohort of 2.9 million anaesthetics and a
large number of airway interventions
in the intensive care units and emergency
departments of the UK. Considered in a positive light NAP4 is the synthesis of
learning extracted from a large series of major airway events collected in a
systematic manner, prospectively, from a large area (the whole of the UK) over
a relatively long period (one year) and with 100% participation.
Industries with good safety records
recognise the value of collecting, analysing and learning from incident reports
relating to adverse outcomes and near misses. NAP4 has used this process in an
attempt to improve the safety of airway management. We are grateful to all the
clinicians who reported events and to the panel of clinicians
who gave their time to review them
and develop the recommendations.
It is our hope that systems for
learning will become embedded in our professional culture.
18
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
■■■■■
CHAPTER 2
Evidence-based medicine and
airway management: are they incompatible?
References
.
1 Harbour R, Miller J. The Scottish Intercollegiate
Guidelines Network Grading Review Group. A new system for grading
recommendations in evidence-based guidelines British Medical Journal Br
2001;323:334–336.
.
2 Scottish Intercollegiate Guidelines Network SIGN
50: A guideline developer’s handbook. Annex B: Key to evidence statements and
grades of recommendations (www.sign.ac.uk/ guidelines/fulltext/50/annexb.html).
.
3 Henderson JJ et al. Difficult Airway Society
guidelines for management of the unanticipated difficult intubation. Anaesthesia
2004;59:594–675.
.
4 Calder I, Yentis SM. Could ‘safe practice’ be
compromising safe practice? Should anaesthetists have to demonstrate that face
mask ventilation is possible before giving a neuromuscular blocker? Anaesthesia
2008;63:113–115.
.
5 Broomhead RH, Marks RJ, Ayton P. Confirmation of
the ability to ventilate by face mask before administration of neuromuscular
blocker: a non-instrumental piece of information? Br J Anaesth 2010;104:313–317.
.
6 Kheterpal S et al. Incidence and predictors of
difficult and impossible mask ventilation. Anesthesiology 2006;105:885–
891.
.
7 Neilipovitz DT, Crosby ET. No evidence for
decreased incidence of aspiration after rapid sequence induction. Can J
Anaesth 2007;54:748–764.
.
8 Levy D. Traditional rapid sequence induction is
an outmoded technique for Caesarean Section and should be modified. Int J
Obs Anaes 2006;15:227–232.
.
9 Vanner RG, Asai T. Safe use of cricoid pressure. Anaesthesia
1999;54:1–3.
.
10 Mason RA, Fielder CP. The obstructed airway in
head and neck surgery. Anaesthesia 1999;54:625–628.
.
11 Nouraei SA et al. Physiological comparison of
spontaneous and positive-pressure ventilation in laryngotracheal stenosis. Br
J Anaesth 2008;101:419–423.
.
12 Cook TM. The classic laryngeal mask airway: a
tried and tested airway. What now? Br J Anaesth 2006;96:149–152.
.
13 Wilkes AR, Hodzovic I, Latto IP. Introducing new
anaesthetic equipment into clinical practice. Anaesthesia 2008;63:571–
575.
.
14 Cook TM. Spoilt for choice? New supraglottic
airways. Anaesthesia 2003;58:107–110.
.
15 Fabregat-López J , Rojo BG, Cook TM. A case
series of the use of the ProSeal laryngeal mask airway in emergency lower
abdominal surgery. Anaesthesia 2008;63:967–971.
.
16 Annamaneni R et al. A comparison of simulated
difficult intubation with multiple-use and single-use bougies in a manikin. Anaesthesia
2003;58:45–49.
.
17 Mihai R et al. A quantitative review and
meta-analysis
of performance of non standard laryngoscopes and rigid fibreoptic
intubation aids. Anaesthesia 2008;63:745–760.
.
18 Frerk CM, Lee G. Laryngoscopy: time to change
our view. Anaesthesia 2009;64:351–354.
19 Pandit JJ et al. Comparison of times to achieve
tracheal intubation with three techniques using the laryngeal or intubating
laryngeal mask airway. Anaesthesia 2002;57:128– 132.
20 Frerk C, Frampton C. Cricothyroidotomy; time for
change. Anaesthesia 2006;61:921–923.
21 Pothier DD. Introducing the concept of the research
governance ‘ratchet’. Research Ethics Review 2006;2:272–273.
22 Hung O, Murphy M. Context-sensitive Airway Management.
Anesth Analg 2010;110:982–983.
23 Cook TM, Morgan PJ, Hersch PE. Equal and opposite
expert opinion. Airway obstruction of a retrosternal thyroid mass: management
and prospective international expert opinion. Anaesthesia (In press),
January 2011.
24 Posner KL, Caplan RA, Cheney FW. Variation in expert
opinion in medical malpractice review. Anesthesiology 1996;85:1049–
1054.
25 Henriksen K, Kaplan H. Hindsight bias: outcome
knowledge and adaptive learning. Quality and Safety in Health Care 2003;122(supp
2):ii46–50.
26 Caplan RA, Posner KL, Cheney FW. Effect of outcome on
physician judgments of appropriateness of care. JAMA 1991;265:1957–1960.
27 Crosby E. Medical malpractice and anesthesiology:
literature review and role of the expert witness. Can J Anaesth 2007;54:227–241.
■■■■■
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
19
CHAPTER 2
Evidence-based medicine and
airway management: are they incompatible?
Dr Tim Cook Dr nick woodall
This chapter is based on the original paper
reporting the results of the naP4 project.
it appears here by kind permission of the
editor-in- Chief and board of the British Journal of Anaesthesia where
it was first published.
Cook TM, Woodall N, Frerk C. Major complications of
airway management in the UK: results of the 4th National Audit Project of the
Royal College of Anaesthetists and the Difficult Airway Society. Part 1
Anaesthesia. Br J Anaesth 2011.
The 4th National Audit Project of
the Royal College of Anaesthetists and the Difficult Airway Society (NAP4) was
established to estimate the incidence of major complications of airway
management in NHS hospitals in the United Kingdom (UK), and to perform a
quantitative and qualitative analysis. Three areas of clinical practice were
identified and considered separately:
▪
airway management during anaesthesia
▪
airway management in the Intensive
Care Unit (ICU)
▪
airway management in the emergency
department.
The following chapters describe the results of this project for
both events during anaesthesia and occurring in ICU and the emergency department.
Methods
A two-part project was devised using
methods based
on the 3rd National Audit project of the Royal College of
Anaesthetists.1 First, a census of airway management
techniques employed in the UK National Health Service (NHS) provided
information on anaesthetic activity
and airway management techniques in current
use (for denominator information: see Chapter 4); second, a registry of the
major complications of airway management over
a 12-month period recorded
details of serious adverse events (for numerator information). Discussions with
the National Research Ethics Service indicated that ethical approval was not
required. The project was examined by the Patient Information Advisory Group of
the Department of Health and the project design was assessed to ensure current
standards of patient confidentiality were met. There was wide consultation with
other specialist societies and organisations with an interest in this area of
clinical care.
Dr Chris frerk
Using surface mail, email and
telephone the anaesthetic department in every NHS hospital in the UK was
contacted and invited to participate in the project and to nominate
a LR who
would act as the point of contact for the audit, co-ordinate the census of
current activity and assist with the second phase during which reports of
individual serious complications were to be submitted. Data were not sought
from private hospitals or Independent Sector Treatment Centres, however data
were collected from treatment centres attached to NHS hospitals.
A detailed written explanation of
the NAP4 project
and the purpose of the census were placed on both
the
Difficult Airway Society (DAS) and Royal College of Anaesthetists (RCoA)
websites. Data collection forms
and information sheets were also made available
for downloading. The project was very widely advertised in
UK journals of
anaesthesia, by specialist societies and by
a poster campaign to promote
awareness and encourage participation. Reminders were sent to hospital LRs
approximately every six to eight weeks throughout the data collection period.
Part 1 Census of clinical activity
(denominator data)
A detailed description of the census
phase has been published,2 and this methodology is described in
greater detail in Chapter 4. Briefly, each LR was asked to return data for a
two-week period in September 2008 that indicated the number of anaesthetics
performed in the hospital with the exception of those performed in the ICU and
emergency department. For each general anaesthetic, detailed information on the
primary airway management technique, defined as that ‘used for maintenance of
anaesthesia’ (face mask, supraglottic airway device or tracheal tube) was
requested. Tracheal intubation included all forms of intubation of the trachea:
i.e. single and double lumen tubes, tracheostomy, surgical bronchoscopy,
transglottic and trans-tracheal techniques. The decision on how to collect
these data was left at the discretion of the LR. Local data were summed to give
cumulative totals and submitted to the project team. After collating all
returns the project team used the submitted data to estimate national annual
activity and primary airway techniques used.
20
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
■■■■■
CHAPTER 3 Methods of NAP4
Part 2 event reporting (numerator data)
inclusion criteria
Triggers for inclusion and
notification to the project were complications of airway management that led to
▪
death
▪
brain damage
▪
need for an emergency surgical
airway
▪
unanticipated ICU admission or
prolongation of ICU stay.
Reports of events occurring in the ICU in the emergency
department or during transfer to or from these departments were also requested
but these were not to be used for the calculation of incidence of complications
associated with anaesthesia. The project did not collect data on events
occurring out of hospital or on hospital wards.
Definitions
Brain damage was available as an inclusion criterion. Although this was not
defined in detail, the manifestations of central nervous system injury and
deficit at one month were requested.
Emergency surgical airway was taken
to include all forms of emergency access to the upper trachea as part of
airway
management (i.e. surgical tracheostomy, surgical cricothyroidotomy, needle or
cannula cricothyroidotomy or tracheotomy). Emergency surgical airway was an
inclusion criterion only when it did not form part of the primary airway
management plan. Thus if a patient presented with critical airway obstruction
and required a surgical airway which was planned and performed successfully
either after tracheal intubation or without attempting intubation the case did
not to meet inclusion criteria. Where the primary airway management plan failed
and a needle/cannula or a surgical airway was performed, this was deemed to
meet inclusion criteria.
ICU admission that was required
as a result of an airway problem was an indication for inclusion. For patients
on the ICU an airway event which would have led to admission to ICU or which
led to prolongation of ICU treatment was an inclusion criterion.
Obesity. Reporters were asked to indicate the patient’s weight and
height and body habitus. Obesity was defined as a Body mass index (BMI) of
>30 kg.m-1 or obese
body habitus.
notification of events
The RCoA-lead (TMC) was notified of events meeting inclusion
criteria by email. LRs or clinicians involved in the event usually informed the
RCoA-lead of an event but notifications were accepted from any source. The
notifier was required to provide their name, the date of the event,
■■■■■
the hospital name and the location
of the event. No other identifying data were accepted including patient or
clinician details. The RCoA-lead then emailed the LR for that hospital,
specifying the project inclusion criteria, and requesting confirmation that the
case did or did not meet criteria and that it was not a duplicate notification.
Moderator
A moderator was available who was
able to discuss the case and offer a confidential opinion on
inclusion/exclusion. The moderator was not part of the case review process
and
could be contacted directly rather than via the RCoA- lead. Cases deemed not to
meet the inclusion criteria were withdrawn from the project before being
submitted for panel review.
secure website
For cases meeting criteria the LR
was issued with a unique identifying number and website access password
enabling a secure connection to the project website for online data submission.
Passwords were issued by the RCoA-lead through the project website using a
remote process. The RCoA-lead had no access to the password itself but was
aware of the unique identification number, which was used to ‘track’ the case.
Data submission
Data were submitted by the LR or the
clinician involved in the case according to the local preference. After logging
on for the first time a mandatory change of access password was required before
proceeding to the reporting forms.
The website directed the person
submitting data to
specific submission forms for reporting of events during
anaesthesia, in ICU or the emergency department. The clinician submitting data
could make multiple visits to
the website to enter additional data as more
information became available. When a report was complete it was closed and
submitted electronically, after which no further changes could be made. The
RCoA-lead was unable to view the submitted data but could follow the progress
of cases online by using the unique identifier to note whether the case was
recorded as ‘password unchanged’, ‘password changed’ or ‘form closed’.
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
21
CHAPTER 3 Methods of NAP4
Table 1 Categories of incident contributory factors. Categories are
taken from the national Patient safety agency document seven steps to patient
safety: a guide for nhs staff12
the DAS-lead was unaware who the
recipient was). The DAS-lead was able to access all submitted files but had no
knowledge of their origin. In contrast the RCoA-lead knew event locations but
had no access to any files. It was a precondition of the project imposed by the
Patient Information Advisory Committee of the Department of Health that these
two pieces of data could not be linked. Identifying numbers were not present on
any information reviewed by the review panel.
The period during which events were
included in
NAP4 ran from 1 September 2008 to 31 August 2009: notifications
were accepted until June 2010, after which the identification numbers issued to
LRs were destroyed by the RCoA-lead.
Case review panel
Each clinical report was reviewed by
a panel of representatives from all the parties involved in the project: the
Royal College of Anaesthetists, the Difficult Airway Society, the Association
of Anaesthetists of Great Britain and Ireland, the Association of Paediatric
Anaesthetists, the Association for Peri-operative Practice, British Association
of Otorhinolaryngologists (ENT-UK), the College of Emergency Medicine, the
College of Operating Department Practitioners, the Intensive Care Society, the
National Patient Safety Agency, the Obstetric Anaesthetists Association and the
Patient Liaison Group of the RCoA.
Case review process
Each clinical case was reviewed at
least twice. At each review meeting the reviewers were divided into two
equal
groups (at least five members with differing clinical backgrounds). Each group
reviewed half of the cases and when these had been reviewed the two groups
re-joined. Each case was then presented and re-reviewed by the whole review
panel. If a report was unclear more information
was sought using the process
outlined previously. The case was first reviewed to determine whether it met
inclusion criteria and to identify duplicate reports. Cases meeting inclusion
criteria were included and reviewed, those which did not were removed. The
review panel indicated if the event showed underlying contributory, causative
or positive factors under the categories described in Table 1. Causal factors
were those that were so prominent that they were considered directly linked to
the event while contributory factors were those that had evidence of impact on
the event without being causal. Positive factors indicated areas judged to be
of notably good management. The degree of harm attributable to the event was
graded using the National Patient Safety Agency (NPSA) severity of outcome
scale for patient safety incidents (Table 2).3 Cases with an
outcome
of death and persisting brain damage
(i.e. brain damage that had not shown evidence of improvement or recovery at
the time the case was reported) were also extracted. Cases
|
factors
|
Positive
|
Contributory
|
Causal
|
|
Communication
(includes verbal, written and non-verbal: between individuals, teams and/or
organisations)
|
|
|
|
|
Education and
Training (e.g. availability of training)
|
|
|
|
|
Equipment/
resource factors (e.g. clear machine displays, poor working order, size,
placement, ease of use)
|
|
|
|
|
Medication
(where one or more drugs directly contributed to the incident)
|
|
|
|
|
Organisation
and strategic (e.g. organisational structure, contractor/ agency use,
culture)
|
|
|
|
|
Patient (e.g.
clinical condition, social/physical/ psychological factors, relationships)
|
|
|
|
|
Task (includes
work guidelines/procedures/ policies, availability of decision-making aids)
|
|
|
|
|
Team and social
(includes role definitions, leadership, support and cultural factors)
|
|
|
|
|
Work and
environment (e.g. poor/excess administration, physical environment, work load
and hours of work, time pressures)
|
|
|
|
|
Other
|
|
|
|
Regular review of the website
enabled the RCoA-lead to identify where there were delays in data submission
and to encourage submission by direct contact with the LR. When a file was
closed (i.e. completed and submitted) this event was notified automatically to
the DAS-lead (NW). Files were downloaded by the DAS-lead and saved in Word and
Excel format for review. If more information was needed files could be
re-opened and a message sent to the LR through the project website by a remote
process (i.e. so
22
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
■■■■■
CHAPTER 3 Methods of NAP4
were analysed for learning points
and some were selected to act as illustrations of clinical care for inclusion
in the current report. Airway management was classified as good, poor, mixed
(elements of both good and poor management), or unclassifiable, reviewers were
reminded of likely outcome4 and hindsight bias.5 Reviewers were instructed on the strict confidentiality of the
process and if a reviewer was aware
of a case (e.g. the case came from
their hospital) external knowledge was not admissible in the review process.
Clear errors in submitted data (e.g. a fatal outcome not being recorded) were
corrected at this time.
Table 2 severity of outcome scale. Categories are taken from the
national Patient safety agency document: seven steps to patient safety: a guide
for nhs staff3
For patients in ICU and Emergency
Departments the main aim of the project was to study the nature of major airway
events in the two identified non-anaesthetic environments. No formal census was
planned to identify a denominator for such events. However during the project
such a census for Emergency Department activity was completed by one of the
authors of this paper.6
Missing reports
Although the individual case reports
were anonymous
the RCoA-lead retained the date and source of individual
reports. Data on the number and source hospital of events was examined for
evidence of clustering by time and
place in an attempt to assess the
completeness of data collection. Reports from LRs (i.e. in which the LR was
also the anaesthetist) were identified. It was assumed that all LRs would
return all cases meeting inclusion criteria and therefore that this small
highly motivated group could
be used to create an upper estimate for the number
of cases that might have been reported if all (consultant) anaesthetists acted
as LRs did.
References
1 Cook TM, Counsell D, Wildsmith JAW. On behalf of the
Royal College of Anaesthetists Third National Audit Project. Major
complications of central neuraxial block: report on the 3rd National Audit
Project of the Royal College of Anaesthetists. Br J Anaesth 2009:102:179–190.
2 Woodall NM, Cook TM. A national census of airway
management techniques employed during anaesthesia in the UK: results of the
first phase of the 4th National Audit Project at the Royal College of
Anaesthetists. Br J Anaesth 2010; e-published December 2010 doi:
10.1093/bja/aeq339.
3 Seven steps to patient safety: a guide for NHS staff.
National Patient Safety Agency, 2004 (www.nrls.npsa.nhs.uk/
resources/?entryid45=59787, accessed 26 December 2010).
4 Caplan RA, Posner KL, Cheney FW. Effect of outcome on
physician judgements of appropriateness of care. JAMA 1991;265:1957–1960.
5 Henriksen K, Kaplan H. Hindsight bias: outcome
knowledge and adaptive learning. Qual Saf Health Care 2003;122(supp
2):46–50.
6 Benger J, Hopkinson S. Rapid sequence induction of
anaesthesia in UK Emergency Departments: a national census. Emerg Med J 2010
doi: 10.1136/emj.2009.085423.
|
grade of severity
|
Description
|
|
None
|
No harm (whether
lack of harm was due to prevention or not)
|
|
Low
|
Minimal harm
but necessitating extra observation or minor treatment*
|
|
Moderate
|
Significant,
but not permanent harm, or moderate increase in treatment**
|
|
Severe
|
Permanent harm
due to the incident***
|
|
Death
|
Death due to
the incident
|
* first aid, additional therapy or
additional medication. Excludes extra stay in hospital, return to surgery or
readmission.
** return to surgery, unplanned
re-admission, prolonged episode of care as in or out patient or transfer to
another area such as intensive care.
*** permanent lessening of bodily
functions, sensory, motor, physiologic or intellectual.
incidence calculations
Cases were included in the numerator
where an airway complication of anaesthesia met inclusion criteria and had been
performed within the data collection period in an NHS hospital. Data were
collected on events in the ICU and emergency departments but were not used in
calculation of the incidence of complications during anaesthesia.
The data were entered into a
Microsoft Excel 2007 spreadsheet (Microsoft Corporation, USA) and incidences
were calculated (by dividing the numerator for a given group by the relevant
denominator). Confidence intervals were derived using binomial probability
tests with the stat- conf programme Handbook of Biological Statistics, 2008
(http://udel.edu/~mcdonald/statconf.html).
■■■■■
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
23
CHAPTER 3 Methods of NAP4
Dr nick woodall Dr Tim Cook
This chapter appears by kind permission of the
editor-in-Chief and board of the British Journal of Anaesthesia where it
was first published.
Woodall NM, Cook TM. National census of airway management
techniques used for anaesthesia in the UK: first phase of the 4th National
Audit Project at the Royal College of Anaesthetists. Br J Anaesth 2011;106:266–271.
Airway management is fundamental to
safe anaesthetic practice and anaesthetists need to be skilled in airway
management techniques. However, complications of airway management have been
reported to be both common and serious.1,2 A recent analysis
of the National Health Service Litigation Authority data for the period
1995–2007 showed claims related to airway management to be the fifth commonest
reason for anaesthesia-related litigation but this group of claims was ranked
equal highest in terms of the proportion of claims related to damage or fatalities
and these claims accounted for 20% of the 50 most costly claims.3
The American Society of
Anaesthesiologists (ASA) has a long-standing interest in closed malpractice
claims arising in the United States of America (USA).4 Claims relating
to airway management are reviewed on a regular
basis,5 these reviews guide clinical practice and allow the role and
effectiveness of recommendations and guidelines to be evaluated.6 No similar systematic detailed appraisal exists in the United
Kingdom (UK), although the National Patient Safety Agency (NPSA) collects
reports of, and responds
to, critical incidents.7 The 4th National Audit Project of the Royal College of
Anaesthetists is an attempt to investigate these areas. This chapter describes
a census, taken over a two-week period, of current UK airway management
practice employed for general anaesthesia. The census provides
an estimate of the annual number of
general anaesthetics performed and the airway management techniques in use.
Methods
Using surface mail, email and
telephone the anaesthetic department in every National Health Service
(NHS)
hospital in the UK was contacted and invited to participate in the 4th
National Audit Project of the Royal College of Anaesthetists (NAP4) and to
nominate a LR (LR) who for phase 1 of the project would co-ordinate a census of
current
Dr Chris frerk
activity. Data were not sought from
private hospitals or Independent Sector Treatment Centres (ISTCs) however data
were collected from treatment centres attached to NHS hospitals.
Each LR was asked to return a
Hospital Data Submission Form by electronic or surface mail for the two-week
period from 15–28 September 2008. Information was requested under two
categories; essential and desirable.
Essential data. Essential data were requested on the number of anaesthetics
performed anywhere in the hospital with the exception of those performed in the
Intensive
Care Unit (ICU) and emergency department: anaesthetics performed in
these areas were explicitly excluded.
Required data were broken down into two
categories;
the number of local or regional anaesthetics performed
by an
anaesthetist without general anaesthesia and the number of general anaesthetics
performed. For procedures undertaken under general anaesthesia detailed
information on the primary airway management technique used was requested.
Specifically the total number of times during the two-week period an
anaesthetic face mask, supraglottic airway device (SAD) or tracheal tube was
employed as the primary airway management technique was requested. The primary
airway was defined as that ‘used for maintenance of anaesthesia’. Tracheal
intubation included all forms of intubation of the trachea: e.g. single and
double lumen tubes, tracheostomy, surgical bronchoscopy, transglottic and transtracheal
techniques.
Desirable data. Supplementary detailed information
was requested on the specific
type of airway device used. Additional questions were also included on the
anaesthetic induction methods for patients in whom airway problems were anticipated.
The decision on how to collect these
data was left at
the discretion of the LR. The data collection exercise
could
be performed using a paper based method or, if facilities existed locally,
information could be collected electronically. To assist, electronic copies of
the NAP4 Anaesthetist’s Data Collection Form, were distributed to LRs for use,
if they elected to use a paper based method, though they were free to create
their own if they deemed this appropriate. A detailed written explanation of the
NAP4 project and the purpose of the census were placed on both the Difficult
Airway Society (DAS) and Royal College of
24
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
■■■■■
CHAPTER 4
Results of the first phase of
NAP4: census
Anaesthetists (RCoA) websites and
the Anaesthetist’s Data Collection Form was also available for downloading from
both websites. An Anaesthetist’s Data Collection Advice Sheet explaining the
data to be collected was provided for distribution by the LRs to individual
anaesthetists. The project was very widely advertised to promote awareness and
encourage participation. LRs collected data on the activities of individual
anaesthetists and submitted a return based on the activities of the whole
hospital.
For each figure submitted, LRs were
asked to indicate
its accuracy as; accurate (0–2% error), close estimate (2–10%
error), estimate (>10% error), or guess (no data to support the figure).
LRs were contacted at regular
intervals by surface mail, email or telephone and encouraged to return data.
If
they found they were unable to fulfil their role alternative volunteers were
identified in their hospitals. When this occurred after 15 September 2008 or if
local circumstances had prevented data collection during the planned census
period LRs were invited to submit data for an alternative two-week period.
Where no data had been received before the end of August 2009 data for the
two-week period from the 14–27 September in 2009 were requested instead.
Submitted electronic data were
checked to identify rogue data such as data entry errors, mathematical errors
or illogical data and these were corrected where possible after consultation
with the LR responsible. If submitted data were conflicting and correction by
the LR was not possible, those data identified by the LR on the submission form
to be the most accurate were used. If an assessment was not possible data were
accepted as presented.
Data for each category from all
hospitals were added to provide a cumulative national total for the two week
period. These totals were then multiplied by 25 to provide an estimate of
annual activity. The multiplier of 25 was based on calculation made in the
authors’ base hospitals. The surgical activity during year 31 August 2008 to 1
September 2009 was divided by the total general anaesthetic activity recorded
during the study period. These were found to be 24.5 at the Norfolk and Norwich
University Hospital and 24.9 at the Royal United Hospital Bath. These were
rounded to 25 to create the multiplier for calculating annual activity.
Validation. In an attempt to validate the data returned by LRs for the total
number of general anaesthetics Hospital Episode Statistics (HES) data8 collected from hospitals in England for the 2008–2009 period
were analysed. This database records the primary procedure performed on NHS
patients over each financial year. The HES data provides numbers for procedures
performed on all NHS patients in England including those treated within the
private sector
or in independent sector treatment
centres. The database provides no information on the type of anaesthesia. A
■■■■■
group of senior clinicians including
anaesthetists with experience in all clinical specialties (including general, orthopaedic,
obstetric, gynaecological, urological, paediatric, vascular, thoracic, cardiac,
head and neck, plastic, otorhinolaryngological, oro-maxillary-facial and
neuro-surgery) reviewed the list of primary procedures
and estimated the
percentage of cases performed under general anaesthesia as 100%, 95%, 75%, 50%,
25%, 5%
or 0%. These multipliers were used to estimate the total performed
under general anaesthesia, for each procedure listed in the HES database. This
figure for England was then multiplied by 1.2 (based on population census
figures for England, Wales, Scotland and Northern Ireland)9 to provide an estimate for the population of the United Kingdom.
Results
By September 2008 all 309 NHS
hospitals had agreed to participate and had appointed a LR. All 309 hospitals
(100%) returned data: ‘essential data’ was returned by 100% and ‘desirable
data’ by 98%.
In the two-week study period a total
of 114,904 general anaesthetics were recorded as having been performed (Table
1). The primary airway management device for general anaesthesia was a SAD in
64,623 (56.2%). The majority
of these were reported to be standard laryngeal
masks. Approximately 10% of anaesthetics were delivered via one of the newer
SADs, the i-gel (Intersurgical, Wokingham, UK) and ProSeal LMA (Intavent
Direct, Maidenhead, UK), with the former being used more than twice as often as
the latter. A tracheal tube was the primary airway in 44,114 (38.4%) general
anaesthetics. The majority of tracheal intubations were performed with a single
lumen tube. Anaesthesia via
a double lumen tracheal tube or tracheostomy
represent, between them, fewer than 1 in 100 general anaesthetics and general
anaesthesia using a surgical laryngo-bronchoscope, trans-tracheal techniques
and bronchial blockers are very infrequent each being used in less than 1 in
1,000 general anaesthetics and fewer than 1 in 500 tracheal intubations.
Anaesthesia by face mask alone was used for 6,167 procedures (5.3%). The
percentage of data returns reported as ‘accurate’ or close estimate’ were:
number of general anaesthetics 89% and by airway device 82–84%.
Extrapolating to annual activity
suggests that in the UK 2.9 million general anaesthetics were performed during
the year of the NAP4 study in the units surveyed. This represents an annual
activity of 1.6 million general anaesthetics in which the airway was maintained
with a SAD, 1.1 million with a tracheal tube and 0.15 million with an
anaesthetic face mask. Subtypes of airway device are summarised in Table 2.
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
25
CHAPTER 4
Results of the first phase of
NAP4: census
Table 1 Main results and airway management techniques (* = to the
nearest 100)
Although not a prime aim of the
census, our returns indicated 27,096 cases performed under local or regional
anaesthesia during the census: an annual estimate of activity of 0.68 million
cases. Using our estimate of general anaesthetic activity this gives a split of
81%:19% for general to regional/local anaesthetic activity, for cases in which
an anaesthetist is involved.
Discussion
This census of general anaesthesia
and airway management activity was primarily designed to provide a realistic
estimate of the total number of general anaesthetics performed annually in the
UK within NHS hospitals. Additional information on the airway management
techniques employed during general anaesthesia was collected. These data will
form the denominators in the calculations of the incidence of major
complications associated with such techniques. Ideally such information would
be available from a continuous nationwide analysis of practice. Currently these
data are collected and available in some UK hospitals but no national
co-ordinated analysis is available to provide this information for the NHS or
the country as a whole.
A study period of two weeks is
relatively short and consideration was given to asking reporters to collect
information over a longer period, however it was thought that a prolonged
period of measurement might represent an unreasonable burden, ultimately
leading to a lower response rate. The response rate (100%) is excellent and,
although self-rated, the reported accuracy of the data (89% described as
‘accurate’ or a ‘close estimate’ for the type of anaesthetic and >82% as
‘accurate’ or a ‘close estimate’
Table 2 Detailed breakdown
of airway techniques used (* = to the
nearest 100)
|
|
uses during census
|
number per annum*
|
Percentage of general
anaesthetics
|
indicated as
‘accurate’ or ‘close estimate’
|
|
General
anaesthetics
|
114,904
|
2,872,600
|
100%
|
89%
|
|
Supraglottic
airway device
|
64,623
|
1,616,100
|
56.2%
|
83%
|
|
Tracheal tube
|
44,114
|
1,102,900
|
38.4%
|
84%
|
|
Face mask
|
6,167
|
154,200
|
5.3%
|
82%
|
In 2,554 (2.2%) patients, airway
management was expected to be difficult as judged by the anaesthetist. Of these
reported predicted difficult airways, 91% were in adults and 9% in children.
Management of patients with predicted difficult airways in adults was
predominantly (81%) with intravenous induction of anaesthesia, with a minority
being managed by inhalational
induction (9%) or awake fibreoptic intubation (10%). In children with predicted
difficult airways inhalational induction (63%) was much more common than
intravenous induction (37%) and awake fibreoptic intubation was not reported at
all.
From the HES data (which includes
ISTCs and NHS patients treated in private hospitals) using the method described
we estimated that 3.0 million general anaesthetics per annum were performed in
all UK hospitals in 2008.
|
(accurate or close
estimate) Two-week total annual estimate * % of all airways % of subgroup
|
|
Face
mask (80) 100
|
|
Anaesthetic
face mask 4,784 119,600 4.2 77.6
|
|
Hudson type of
mask 1,383 34,600 1.2 22.4
|
|
Supraglottic
airway (80) 100
|
|
Laryngeal mask
56,388 1,409,700 49.2 87.3
|
|
i-Gel 4,574
114,400 4.0 7.1
|
|
ProSeal LMA
1,920 48,000 1.7 3.0
|
|
Other 1,741
43,500 1.5 2.7
|
|
Tracheal
tube (81) 100
|
|
Single lumen
42,752 1,068,800 37.3 96.9
|
|
Double lumen
634 15,900 0.55 1.4
|
|
Tracheostomy
399 10,000 0.35 0.9
|
|
Surgical
laryngo-bronchoscope 133 3,300 0.12 0.3
|
|
TTJV 83 2,100
0.07 0.19
|
|
Bronchial
blocker 60 1,500 0.05 0.14
|
|
Other 53 1,300
0.05 0.12
|
26
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
■■■■■
CHAPTER 4
Results of the first phase of
NAP4: census
for the primary airway management
device) supports the decision to pursue a ‘snapshot’ approach, meaning that
robust denominator data are available for use with the data from the 12-month
review of complications. The 100% compliance rate probably reflects the
recognised importance of the overall aim of the project and the persistence
with which data were sought. The support of all the key organisations (see
Acknowledgements) was vital in demonstrating that importance: their support, as
well as that of the LRs, is greatly appreciated.
To provide an estimate of annual
activity the results of
the two-week census were multiplied by 25 on an empiric
basis supported by data from the authors’ hospitals. It is postulated that
elective surgical activity is reduced during holiday periods, by bank holidays
and perhaps when new trainees are introduced though urgent/emergency surgery
continues. Our multiplier of 25 equates to approximately 49–50 weeks of both
elective and emergency work, and two to three weeks of emergency only work,
this having
a differential effect on the several anaesthetic sub- specialties.
In the Royal United Hospital, Bath, a large district general hospital, the
total number of procedures performed annually is available and leads to
multiplication factors between 23.5 and 26 for each specialty, and an overall
multiplier of 24.9. When the number of general anaesthetics for the year 2008
was divided by the number of general anaesthetics performed at the Norfolk and
Norwich hospital during the survey period in September 2008 the multiple was
24.5. Therefore on the basis of these data 25 was accepted and applied to all
data.
Though not a prime aim of the census
our data suggests approximately 19% of anaesthetists’ NHS surgical activity
(about 0.7 million cases per annum) involved cases performed under regional or
local anaesthesia alone. The framing of this question in the census means it is
possible this figure excludes regional analgesia for labour which would add an
additional 110,000 cases.10 Depending on whether these cases
were captured regional anaesthesia (without general anaesthesia) is likely to
account for 20–22% of anaesthetic activity.
The Royal College of Anaesthetists
has direct links to all NHS hospitals and these links were considered to form a
reliable collection network (for both this and the second stage of the
project). In order to ensure that incidence calculations are as accurate as
possible numerator data (numbers of complications) are drawn from the same
population as the census. Cases reported from ISTC and private sector hospitals
may have been submitted during the second phase of NAP4 but these were not to
be used for the calculations of incidence.
We believe the results of this
census are the first robust attempt to determine the number of general
anaesthetics delivered in the UK: this is something of a surprise. The
■■■■■
RCoA census of anaesthetic activity
in 2007 estimated
there were 12,600 anaesthetists in the UK.11 Our data could therefore mean each anaesthetist delivers an
average of 230 general anaesthetics per year in the NHS. On initial examination
this figure may appear to be low and this justifies further examination. We
have collected data
on the number of general anaesthetics, not the number
of
anaesthetists delivering them. If we assume one-
third of anaesthetics are
delivered by two anaesthetists (consistent with figures from the authors’
hospitals) our figures would equate to the average figure of general
anaesthetics delivered by UK anaesthetists in NHS hospitals of approximately
340 per annum. If 10% of all anaesthetists (as in the RCoA census) work
half-time the mean full-
time equivalent figure rises to 360 general
anaesthetics
per annum. Of course this figure does not include cases managed
under local or regional anaesthesia alone: perhaps accounting for an additional
25% based on data collected in this audit. The mean figure is also lowered by
the inclusion of anaesthetists on long-term sickness, or maternity leave.
Finally, anaesthetists are heavily engaged in other activities including
provision of intensive care, obstetric analgesia, acute and chronic pain
management, pre-operative assessment clinics, research, teaching, and hospital
management: each of these activities will reduce the number of general
anaesthetics delivered by those involved and the mean figure overall. Pooled
data from each of
the authors’ hospitals gave a mean figure which ranged from
324–333 general anaesthesia cases per annum for consultants with local or
regional anaesthesia accounting for 20–30% of anaesthetics administered.
The vast majority of tracheal
intubations were performed with a single lumen tube (over one million). Our
estimate of the frequency of use of other tracheal intubation techniques are
based on small numbers and are therefore the least reliable of those we quote.
Anaesthesia via a double lumen tracheal tube or tracheostomy represent, between
them, fewer than 1 in 100 general anaesthetics and general anaesthesia using a
surgical laryngo-bronchoscope, trans-tracheal techniques and bronchial blockers
are very infrequent each being used in less than 1 in 1,000 general
anaesthetics and fewer than 1 in 500 tracheal intubations. Accepting any
reservations about the absolute accuracy of these figures it is likely that
these techniques are performed in a relatively small number of centres and by a
relatively small number of anaesthetists: there is corroborative evidence for
this for the usage of surgical laryngo- bronchoscope and trans-tracheal
techniques.12 These findings have potential implications for the use of such
techniques in emergencies and by non-experts. Indeed they are relevant for
instance to the finding in this report of a low success rate for rescue cannula
cricothyroidotomy when performed by anaesthetists, as discussed elsewhere in
this report (see Chapters 5 and 13).
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
27
CHAPTER 4
Results of the first phase of
NAP4: census
The study has intrinsic weaknesses.
First, whatever method was used to collect data it is likely any final figure
will be an under-estimate of actual activity as cases are far more likely to be
missed or omitted than fabricated. Second, repeated approaches to some units
were required to obtain data.
The delayed recording of data is
likely to lead to a further underestimation of the denominator since forms
completed retrospectively may be affected by lapse of memory of the individual
anaesthetists, leading to omissions. Third, the increasing subdivisions of data
make the smaller numbers more prone to variance both because sampling
infrequently used devices over a short time period is prone to error and
because these figures were reported by the LRs as being
less accurate. As a result
we have more confidence in the broader figures (e.g. mask vs SAD vs tracheal
tube) than subdivisions. Fourth, the range of accuracies of reported data makes
it difficult to present confidence intervals for
the data we report and we
simply offer point estimates. Finally the data we used for validation is itself
not externally validated and the method we used to estimate the number of
general anaesthetics from that database has considerable weaknesses, although
we are not aware of any better methods of validation. We acknowledge all these
limitations but complete compliance with the census and the self- assessed
accuracy of the data both support the view that these data are of as high a
quality as it is feasible to collect. For the number of general anaesthetics
the LRs reported 89% of submissions to be accurate to within 10%. If we accept
this figure and assume 50% error of the remaining 11% we estimate an error in
our final figure of no more than 15%. For reasons outlined previously most
figures returned will be underestimates but some will be in excess of the
number of cases actually performed and these will tend to reduce the degree of
inaccuracy. We welcome information from others that might enable us to refine
our estimates.
The overall estimate of 2.9 million
general anaesthetics performed in the UK within the 309 units surveyed is very
similar to the estimate of three million derived from HES data which also
includes NHS patients treated in private hospitals and ISTCs. Independent
sector treatment centres were estimated to account for 1.8% of elective NHS
activity in 2007–200813 and private practice accounts for
approximately 10% of surgical activity in the UK.14 Using
these broad estimates it is likely the overall number of general anaesthetics
in the UK is between 3.1–3.3 million: though the assumptions used make this
figure rather less accurate than the figure reported here for activity in NHS
hospitals.
In conclusion, a national survey of
the four countries making up the UK was undertaken to provide an estimate of
the number of general anaesthetics performed in one year in UK NHS hospitals
and to identify the pattern of airway management techniques used for these
cases. We estimate 2.9 million general anaesthetics were performed
in this population in 2008–2009: 56%
utilising a supraglottic airway, 38% via tracheal tube and 5% using an
anaesthetic face mask. These data are used as the dominator for calculating an
estimated incidence of major complications of airway management techniques in
the UK: see subsequent chapters.
References
.
1 Utting JE. Pitfalls in anaesthetic practice. Anaesthesia
1987;59:877–890.
.
2 Gannon K. Mortality associated with anaesthesia.
A case review study. Anaesthesia 1991;46:962–966.
.
3 Cook TM, Scott S, Mihai R. Litigation related to
airway and respiratory complications of anaesthesia: an analysis of claims
against the NHS in England 1995–2007. Anaesthesia 2010;65:
556–563.
.
4 Caplan RA et al. Adverse respiratory events in
anesthesia: A closed claims analysis. Anesthesiology 1990;72:828–833.
.
5 Gene N et al. Management of the Difficult Airway.
A Closed ClaimsAnalysis. Anesthesiology2005;103:33–39.
.
6 Special Article. Practice Guidelines for
Management of the Difficult Airway. An Updated Report by the American Society
of Anesthesiologists Task Force on the Management of the DifficultAirway. Anesthesiology2003;98:1269–1277.
.
7 Smith AF, Mahajan RP. National critical incident
reporting: improving patient safety. Br J Anaesth 2009;103:623–625.
.
8 HES online. Hospital Episode Statistics (www.hesonline.nhs.
uk/Ease/servlet/ContentServer?siteID=1937&categoryID=459, accessed 6 April
2010).
.
9 Population estimate for UK in 2008. Office of
National Statistics (www.statistics.gov.uk/cci/nugget.asp?id=1352, accessed
6 April 2010).
.
10 NOAD report Data. OAA, London 2007
(www.oaa-anaes. ac.uk/assets/_managed/editor/File/NOAD/NOAD_2007_data_
report.pdf, accessed 6 May 2010).
.
11 McLaughlan C. RCoA Bulletin 2008;50:2577–2578.
.
12 Cook TM, Alexander R. Major complications during
anaesthesia for elective laryngeal surgery in the United Kingdom: a national
survey of the use of high pressure-source ventilation. Br J Anaesth 2008;101:266–272.
.
13 Naylor C, Gregory S. Independent sector
treatment centres. Kings Fund Briefing, October 2009
(www.kingsfund.org.uk/ document.rm?id=8457, accessed 7 May 2010).
.
14 Laing’s Healthcare Market Review and Directory
of Financial Information. Laing and Buisson, 2009–2010. 22nd edition
(ISBN: 978-1-85440-140-3).
28
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
■■■■■
CHAPTER 4
Results of the first phase of
NAP4: census
Dr Tim Cook Dr nick woodall
This chapter is based on the original paper
reporting the results of the naP4 project.
it appears here by kind permission of the
editor-in- Chief and board of the British Journal of Anaesthesia where
it was first published.
Cook TM, Woodall N, Frerk C. Major complications of
airway management in the UK: results of the 4th National Audit Project of the
Royal College of Anaesthetists and the Difficult Airway Society. Part 1
Anaesthesia. Brit J Anaesth 2011.
Introduction
Dr Chris frerk
The 4th National Audit Project of
the Royal College of Anaesthetists and the Difficult Airway Society (NAP4) was
established to estimate the incidence of major complications of airway
management in NHS hospitals in the United Kingdom (UK), and to perform a
quantitative and qualitative analysis. Three areas of clinical practice were identified
and considered separately:
▪
airway management during anaesthesia
▪
airway management in the Intensive
Care Unit (ICU)
▪
airway management in the emergency
department.
The following chapter describes the results of this project in
ICU and the emergency department.10
Methods are described in Chapter 3.
Results
Agreement to participate and
appointment of a LR was established in all 309 NHS hospitals by September 2008.
In total 286 LRs were appointed with some representing more than one hospital.
Table 1 Clustering of cases by hospital. analysis of
reviewed cases
Airway management is fundamental to
safe anaesthetic practice and in most circumstances is uncomplicated but it has
been recognised for many years that complications of airway management occur
with serious consequences.1,2 Good quality information on
the frequency and nature
of major adverse events related to
anaesthetic airway management is incomplete. Litigation based analyses
add some
insight into the severity of such events and
have driven changes in practice.3–6 These indicate that airway and respiratory complications leading
to litigation are a small proportion of all litigation claims against
anaesthetists but are associated with notably high rates
of death and brain
damage, high rates of ‘less than appropriate care’ and high costs. Due to the
complexity
of the relationship between complications and litigation, and the
lack of denominators they do not add information about prevalence or incidence
of complications.7–8 Analyses of critical incident
reports in the UK have also added useful information but these reports largely
focus on minor incidents and are likely to miss a considerable proportion of
major events.9
Knowledge of the incidence of such
complications
should be an important component of clinical decision- making,
risk management and the consent processes. Information on serious and common
complications should guide the specialty into appropriate areas for research
by
demonstrating areas in which our current practice or performance can improve.
|
number of cases
reported
|
number of hospitals
|
% of hospitals
|
% of all cases
|
|
7
|
1
|
0.3%
|
3.3%
|
|
6
|
0
|
0.0%
|
0.0%
|
|
5
|
1
|
0.3%
|
2.4%
|
|
4
|
9
|
2.9%
|
17.2%
|
|
3
|
8
|
2.6%
|
11.5%
|
|
2
|
26
|
8.5%
|
24.9%
|
|
1
|
85
|
27.7%
|
40.7%
|
|
0
|
177
|
57.7%
|
0.0%
|
|
Sum
|
307
|
100%
|
100%
|
■■■■■
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
29
CHAPTER 5
Results of the second phase of
NAP4: overall results and anaesthesia
numerator data (complications reported)
A total of 286 cases were reported
to the RCoA lead or discussed with the moderator. Seventy-nine reports were
withdrawn after discussion with the moderator or after the reporter reviewed
the inclusion criteria sent by the RCoA lead: 207 cases were reviewed by the
review panel. During the review process additional information, using the
methods described in Chapter 3, was requested from the reporters of 12 of the
cases. After final review 184 reports met the inclusion criteria. Of the 184
reports 133 complicated the management of anaesthesia, 36 occurred in patients
on ICU and 15 in the emergency department.
Capture of cases
Hospital clustering: reports were
received from 42%
of hospitals and a minority of hospitals accounted for
disproportionately high percentages of reported cases. Table 1 shows numbers of
cases reported by hospitals for the 207 reviewed. Four percent of hospitals
reported 23% of cases, 6% reported 34% and 15% reported 59% of these cases. An
analysis of the distribution of reports suggested they did fit a Poisson
distribution, consistent with complete data capture, but not confirming it.
Person clustering: LRs reported 19
anaesthesia-related events (i.e. the LR was also the anaesthetist in 19 cases)
out of 130 where this information was provided. There were 286 LRs and the 2007
Royal College of Anaesthetists census identified 6,233 consultant anaesthetists11 (i.e. LRs are 4.6% of all consultant anaesthetists). If all
consultant anaesthetists behaved as LRs we might anticipate 19 x 6,233/286 =
414 reports from consultants. As 36% of cases occurred in the absence of a
consultant this figure for all anaesthetists might increase to 414 x
100/(100–36) = 414
x 1.56 = 646. As this figure is
based on only 130 of the 133 anaesthesia cases our upper limit of cases is 646
x 133/130= 661. This figure suggests that, at worst, we captured approximately
1 in 5 of relevant cases. It is likely this figure should be adjusted further:
part-time consultants account for 10% of the consultant workforce and up to a
third of departmental ‘consultant anaesthetist’ activity is delivered in ICU,
pain clinics, management and academia. Further adjustments might be made that
are almost limitless and increasingly speculative but we conclude that we may
only have captured 1 in 3 or 1 in 4 cases that occurred.
Table 2 incident reports classified (1) by asa grade and type of event,
(2) by age and type of event, and (3) by inclusion criteria provided by the
reporter. More than one inclusion criterion could be chosen. note that some
deaths were considered by the review panel not to be causally related to the
event, in other cases patients reported with an inclusion criterion of brain
damage either made a full recovery at the time of reporting or died. Therefore
figures in this Table do not exactly match final outcomes in Table 3.
|
all cases anaesthesia
(n=184) (n=133)
|
|
ASA
|
|
1 2623
|
|
2 6251
|
|
3 5940
|
|
4 2913
|
|
532
|
|
Not recorded 5
4
|
|
Age
|
|
<10 108
|
|
11–20 8 6
|
|
21–40 39 26
|
|
41–60 56 41
|
|
61–80 60 44
|
|
>80 107
|
|
Not recorded 1
1
|
|
Reporter
provided inclusion criteria
|
|
Death 33 14
|
|
Brain Damage 13
6
|
|
ESA 75 54
|
|
ICU admission*
122 100
|
|
(sum) (243)
(174)
|
*prolongation of stay in the case of patients already in
ICU
Demographic data
The distribution of patients by ASA
grade is shown in Table 2. In all cases there were 113 males and 71 females and
in anaesthesia cases 82 males and 51 females. The majority
of patients involved
in anaesthesia cases were ASA grade
1 or 2 (56%), males (62%) and age <60 years (61%). A BMI of >30 kg.m-2 or obese body habitus was recorded in 40% of reported
anaesthesia cases and a BMI of <20 kg.m-2 or cachexia in 11%. The majority
(54%) of the procedures
for which anaesthesia was being induced were elective
or scheduled. Sixty-nine percent of all events occurred during normal working
hours (08.01–18.00), 17% out of hours before midnight (18.01–24.00), 14% out of
hours after midnight (00.01–08.00): for events during anaesthesia a
30
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
■■■■■
CHAPTER 5
Results of the second phase of
NAP4: overall results and anaesthesia
greater proportion took place during
the day (76%, 08.01– 18.00), and a lesser proportion overnight (6%,
00.01–08.00). The anaesthesia events occurred most commonly in
the operating
theatre 47%, then anaesthetic room 37%
and recovery unit 14%. The phase of
anaesthesia was at induction 52%, during maintenance 20%, during emergence 16%
and in the recovery phase 12%. In 63% of anaesthesia cases the most senior
anaesthetist present at the start of the event was a consultant. A locum
anaesthetist was the main anaesthetist in 5% of cases. A request for help
around the time of an anaesthetic airway event was recorded in 95 (70%) cases
and assistance arrived without request in a further four. The speed of response
to a request for help was recorded
in 99 cases: 32 in less than one
minute, 43 in one to four minutes, 21 in five to 30 minutes and three after
more than 30 minutes. Of 97 identified responders 69 were consultants in
anaesthesia/intensive care medicine, 13 consultant surgeons, 11 senior
anaesthesia trainees, two anaesthetic non-consultant career grades and two
surgical trainees. Of 70 requests for help made during the airway event, in 21
the response time was less than one minute, in 36 was one to four minutes, in 11
was five to 30 minutes and in two was more than 30 minutes: five of the 13
events with a response time exceeding five minutes occurred out of hours.
inclusion criteria and event outcomes
The inclusion criteria indicated by
reporters are presented in Table 3. The final outcome of events is presented in
Table 4, first focusing on outcomes of death and brain damage and also by NPSA
classification of severity of harm.
Deaths
Death resulting from an airway
problem was the inclusion criterion for 33 reports (Table 3), of which 14
occurred during anaesthesia, 16 in ICU and three in the emergency department.
In ten further cases the reporter indicated a lesser severity inclusion
criterion but also that the patient died before the report was submitted. Of
these ten ‘late deaths’ the airway event was judged causal in three,
contributory in two and unrelated in five. In total there were therefore 38
deaths attributable to an airway event: 16 during anaesthesia, 18 on ICU and
four in the emergency department. Hypoxia was the common theme in deaths caused
by an airway problem, though in several late deaths, sepsis and single or
multi-organ failure was recorded. Death rate for all cases was 38/184, 20.7%
and for events during anaesthesia 16/133, 12.0%.
Table 3 final outcome 1) narrative outcome, 2) nPsa classification (see
Chapter 3)
|
|
all cases (n=184)
|
anaesthesia (n=133)
|
|
Final
outcome (narrative)
|
|
|
|
Death
|
38
|
16
|
|
Brain damage
|
8
|
3
|
|
Other partial
recovery
|
10
|
6
|
|
Full recovery
|
124
|
106
|
|
Unrelated death
|
4
|
2
|
|
Final
outcome (NPSA definitions)
|
|
|
|
Death
|
38
|
16
|
|
Severe
|
10
|
5
|
|
Moderate
|
126
|
103
|
|
Low
|
7
|
6
|
|
None
|
3
|
3
|
Brain damage
In 13 patients brain damage was
provided as an inclusion criterion (Table 3), and three other cases were
identified during case review. Six of these patients died and two made a full
recovery (e.g. post-event fitting or depressed level of consciousness that
fully resolved). Eight cases of persistent non-fatal brain damage were
identified: three events occurred during anaesthesia, four in ICU and one in
the emergency department. Reported outcomes included permanent low conscious
level, neuro-behavioural deficit
or ‘persistent vegetative state’ (recorded
after one month although it would require one year to elapse before this
diagnosis could be made). Combined rate of death and brain damage for all cases
was 46/184, 25.0% and for events during anaesthesia 19/133, 14.3%.
emergency surgical airway
An attempt at emergency surgical
airway was reported in 80 of 184 reported cases (43%) with only 75 being
recorded as indications for inclusion. An emergency surgical airway was
attempted in 58 (43%) of the 133 anaesthesia-related reports.
In 29 anaesthesia cases the first
choice for emergency surgical airway was tracheostomy: 18 in semi-controlled
circumstances where intubation had failed or not been attempted but the airway
could be maintained on a face mask or laryngeal mask and in 11 cases as a true
emergency rescue technique for a patient in extremis. All emergency
tracheostomies were successful (i.e. tracheal tube placement in the trachea was
achieved, though not always without difficulty or delay). Two patients in this
group died, one because the tracheostomy was not able to bypass a low-
■■■■■
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
31
CHAPTER 5
Results of the second phase of
NAP4: overall results and anaesthesia
lying obstructing tracheal tumour
and one died later due
to severe hypoxia occurring before the tracheostomy was
performed. Cricothyroidotomy was the first approach in 29 cases: 19 with a
narrow bore (³2mm) cannula,
seven with a wide bore cannula and three with a surgical approach. Twelve of 19
narrow bore cannula cricothyroidotomy failed with rescue achieved by surgical
tracheostomy in seven, surgical cricothyroidotomy in two, wide bore cannula in
one and successful oral intubation in two. Three out of seven wide bore
cannulae failed and were rescued with tracheostomy, surgical cricothyroidotomy
or tracheal intubation. The three first choice surgical cricothyroidotomies
were all successful. Of 58 attempts at emergency surgical airway nine (16%)
failed to rescue the airway: 51 (88%) patients made a full recovery from the
incident, three (5%) a partial recovery and four (7%) died: two after
successful surgical airway and two after failure.
Of the 58 cases requiring emergency
surgical airway this was performed by a surgeon in 33 cases (mostly head and
neck surgeons during relevant cases) and by an anesthetist in 25. Only nine of
these 25 anaesthetic attempts
were successful in rescuing the
airway; 11 failures were rescued by a surgeon-performed tracheostomy, one by
percutaneous tracheostomy placed by a colleague, three by tracheal intubation
and one patient died.
iCu admission
ICU admission (or prolongation of
stay) was reported as
an inclusion criterion in 122 cases, including 100
patients following an airway event during anaesthesia. Reported indications for
admission to ICU following anaesthesia- related events were to manage airway
swelling or trauma
in 38 patients, aspiration of gastric contents or blood in
32, hypoxia due to post-obstructive pulmonary oedema in 13, failure to awaken
after surgery in 13, myocardial ischaemia or cardiac arrest in four. Other
reports cited problems with oxygenation and ongoing airway obstruction. Of the
100 admitted to ICU following an anaesthesia-related airway event 12 died,
seven made a partial recovery and 81 were reported to have made a full
recovery. Of the 29 patients admitted to ICU with aspiration of gastric
contents in 23 aspiration during anaesthesia was the primary airway event,
while in six it complicated another primary event: eight of these patients died
and two suffered brain damage.
Primary airway problem during anaesthesia
The recorded primary airway problem
for all events and for anaesthesia events is shown in Figure 1. Problems with
tracheal intubation were the most frequently recorded. Difficult or delayed
intubation, failed intubation and ‘can’t intubate can’t ventilate’ (CICV) were
prominent problems accounting for 39% of all events and events during
figure 1 Primary airway problem
32
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
■■■■■
CHAPTER 5
Results of the second phase of
NAP4: overall results and anaesthesia
Table 5 incidence estimates of major airway complications by airway
type for events and death/brain damage: expressed as events per million cases
and fractions (1 in n cases). The denominator for each calculation is from the
4th national audit project Census.12 for each, point estimate and lower and upper
confidence limits (Cl) are presented
|
|
|
|
events per million
cases
|
events as fractions 1
in n cases
|
|
Type of event
|
numerator
|
Denominator
|
Point estimate
|
lower Cl
|
upper Cl
|
Point estimate
|
lower Cl
|
upper Cl
|
|
Events
|
133
|
2,872,600
|
46.3
|
38.4
|
54.2
|
21,598
|
26,021
|
18,461
|
|
Deaths
|
16
|
2,872,600
|
5.6
|
2.8
|
8.3
|
179,538
|
352,033
|
120,495
|
|
Death/brain
damage
|
19
|
2,872,600
|
6.6
|
3.6
|
9.6
|
151,189
|
274,717
|
104,294
|
|
Tracheal tube
events
|
91
|
1,102,900
|
82.5
|
65.6
|
99.5
|
12,120
|
15,254
|
10,054
|
|
Tracheal tube
death/ brain damage
|
10
|
1,102,900
|
9.1
|
3.4
|
14.7
|
110,290
|
290,087
|
68,089
|
|
SAD events
|
35
|
1,616,100
|
21.7
|
14.5
|
28.8
|
46,174
|
69,051
|
34,684
|
|
SAD death/brain
damage
|
8
|
1,616,100
|
5.0
|
1.5
|
8.4
|
202,013
|
657,942
|
119,325
|
|
FM event
|
7
|
154,200
|
45.4
|
11.8
|
79.0
|
22,029
|
84,985
|
12,654
|
|
FM death/brain
damage
|
1
|
154,200
|
6.5
|
0.0
|
19.2
|
154,200
|
0
|
52,095
|
anaesthesia. Aspiration then
extubation problems followed tracheal intubation in frequency of reported
complications. Amongst anaesthesia events aspiration, CICV and problems during
use of a supraglottic airway, iatrogenic airway trauma and failed mask
ventilation were the next most prominent complications.
Table 4 Primary airway used or intended for maintenance of anaesthesia
phase of NAP4 was 2.9 million
(2,872,600)12 giving a minimum incidence (point estimate) of
133/2,872,600:
i.e. 46 per million or approximately one per 22,000 general
anaesthetics. Using binomial statistics we can estimate an upper 95% confidence
limit of 54 per million and a lower confidence interval of 38 per million
(though as the actual event rate in our population cannot be lower than that we
observed some might omit this value).
Using the same methodology we can
calculate the point estimate and confidence intervals for incidence of death (or
death and brain damage) from an airway event during general anaesthesia (Table
5), The census data also provided estimates of frequency of use of airway
devices (tracheal tube, supraglottic airway device and face mask) and estimates
of the risk of events and poor outcomes with these devices can be derived
(Table 5).
Case-mix
aspiration of gastric contents
Aspiration of gastric contents was
the primary event in 23 anaesthesia cases, two emergency department cases
and
no ICU cases. It was the commonest cause of death in the anaesthesia group
accounting for eight deaths and two cases of brain damage. Aspiration occurred
most frequently in patients with risk factors (>90%), at induction of
anaesthesia or during airway instrumentation (61%). Planned airway management
was as follows: laryngeal mask 13, i-gel one, tracheal tube eight, none one.
Aspiration occurred before airway instrumentation in five cases and during
airway placement in two. Two cases had clear indications for rapid sequence
induction (RSI) and in several others its use could be argued, one case
occurred during RSI laryngoscopy. Management of the cases was judged good in
four, mixed
|
airway
|
|
|
Tracheal
intubation (including fibreoptic intubation)
|
82
|
|
Laryngeal mask
airway
|
32
|
|
Hudson
mask/nasal cannulae
|
4
|
|
Rigid
bronchoscopy
|
4
|
|
Another
supraglottic device
|
3
|
|
Anaesthetic
face mask +/- oropharyngeal airway
|
3
|
|
Tracheostomy
|
3
|
|
New
tracheostomy or cricothyroidotomy
|
2
|
|
TOTAL
|
133
|
Primary airway device during anaesthesia
For anaesthesia events the airway in
use or intended
for maintenance was: tracheal tube of any sort (91),
supraglottic airway device (35), face mask (seven). More detail is given in
Table 4.
incidence of incidents
The total number of events reported
in relation to anaesthesia was 133. The number of anaesthetics administered in
the same period derived from the census
■■■■■
naP4 Report and findings of the 4th National Audit Project of The
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33
CHAPTER 5
Results of the second phase of
NAP4: overall results and anaesthesia
in seven and poor in eight, with
management judged poor in four deaths. Aspiration also complicated other
primary events (secondary aspiration), most frequently difficult or failed
intubation. There were six such events in anaesthesia cases. Aspiration of
blood was the primary event in five anaesthesia cases, one of which led to
death.
head and neck cases
Seventy-two reported cases (39%)
involved an airway problem in association with an acute or chronic disease
process in the head, neck or trachea. Approximately 70% of these reports were
associated with obstructive lesions within the airway. The qualifying airway
event was death or brain damage in 13 cases, emergency surgical airway in 50
and unexpected ICU admission in 27. The outcome at time of form completion (if
recorded) was death in
17, partial recovery in two and full
recovery in 51 cases. These cases included 55 anaesthesia cases. Forty-two
involved anaesthesia for diagnostic or resection surgery, with problems
occurring at induction in 21 cases, during maintenance in eight and during
extubation or recovery in 13. In ten patients complications arose during
induction
of anaesthesia primarily to secure a critical airway. Three
complications were reported in patients following elective head and neck
surgery, who returned to theatre from wards for urgent re-operation. The
reviewers assessed airway management as poor in nearly one-third of reported
cases. Issues of assessment, planning and communication within teams were
prominent in these cases.
obstetrics
There were four reported events in
pregnant women: all involved emergency Caesarean section and problems at the
time of intubation. All took place out of hours and involved complex patients
(two of whom had a BMI >35kg/m2) and were
managed by senior anaesthetists: in two a consultant was present throughout, in
one a staff grade and in one a year 6 specialist trainee. Consultants attended
in all cases. Two cases occurred during an operation where anaesthesia was
induced for failed regional anaesthesia. One patient had a secondary aspiration
(i.e. aspiration complicated another primary airway event), one had a failed
cricoithyroidotomy attempt and one a successful surgical airway. All were
admitted to ICU and made a full recovery.
Paediatrics
There were ten events in children
under the age of ten years: eight during anaesthesia, and one each in ICU
and
in the emergency department. Five cases involved infants and nine children aged
<4. Outcomes included three deaths. Of the eight anaesthetic complications,
there were four cases of difficult intubation (two of which were due to
subglottic narrowing), two aspirations (one of blood after tonsillectomy), one
due to tracheal tube blockage by secretions and one patient required an
emergency tracheostomy during the
removal of a foreign body. One child died, one had persistent stridor and six
recovered fully. All patients were anaesthetised in the presence of a
consultant. The review panel considered airway management to be good in two
cases, mixed in four cases, poor in one and had inadequate information to
comment in one case.
obesity
Seventy-seven of 184 patients (42%)
were obese of whom 19 (25%) suffered death or brain damage, the same rate as
the non-obese population. Of 53 events during anaesthesia in obese patients
four resulted in death and one persistent neurological deficit: a rate of 9%,
lower than the rate in non-obese anaesthesia cases, 18%.
In anaesthesia cases some form of
airway assessment was recorded in 36 and difficulty was anticipated in 25. The
primary airway problem related to tracheal intubation in similar proportions of
obese and non-obese patients (23 of 53 vs 33 of 80). Eight reports described
aspiration, seven extubation problems and four airway trauma. Airway management
was assessed as good in 12 cases, mixed
in 23, poor in 15 and unassessable
in three. The most frequently cited causal or contributory factors were patient
in 42 cases, judgement in 29 and education/training in
20. Several patients
experienced complications of airway management during general anaesthesia when
regional anaesthesia would have been a suitable alternative for surgery, but of
note five obese patients also developed airway complications after requiring
general anaesthesia when a regional anaesthetic technique or sedation failed: a
situation observed in only one non-obese patient.
events at the end of anaesthesia and
in recovery
There were 38 events at the end of
anaesthesia or during the recovery period; 20 in the operating room, 16 in the
recovery room and two occurred in transit between these locations. Airway
obstruction was the most common problem: causes included laryngospasm, complete
occlusion of an airway device by patient biting, blood in the airway or airway
swelling (in three patients this followed surgery in the Trendelenburg
position). Diagnosis of airway obstruction was not always prompt, particularly
in recovery. Two patients died following events occurring in the recovery room.
In one case an inhaled blood clot after tonsillectomy produced total tracheal
obstruction which was initially attributed to asthma and led to fatal cardiac
arrest. In
the other airway obstruction
resulted in pulmonary oedema and severe hypoxia requiring cardiopulmonary
resuscitation (CPR). The patient subsequently died in ICU. In total five
patients developed severe hypoxia requiring CPR. Negative pressure pulmonary
oedema was seen frequently after these obstructive events and required
admission to ICU in 13 cases, 12 of whom made a full
34
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
■■■■■
CHAPTER 5
Results of the second phase of
NAP4: overall results and anaesthesia
Table 6 factors assessed by review panel to contribute or cause events
and factors indicating good practice. for definitions of factors listed (see
Chapter 3)
|
factors
|
all cases (n=184)
|
anaesthesia (n=133)
|
|
Causal
|
Contributory
|
Positive
|
Causal
|
Contributory
|
Positive
|
|
Communication
|
4
|
38
|
40
|
2
|
26
|
20
|
|
Education and
Training
|
12
|
77
|
17
|
10
|
52
|
13
|
|
Equipment and resources
|
2
|
46
|
21
|
2
|
30
|
16
|
|
Medicines
|
0
|
31
|
5
|
0
|
21
|
5
|
|
Organisation
and strategic
|
1
|
42
|
35
|
1
|
35
|
28
|
|
Patient
|
37
|
103
|
1
|
28
|
76
|
1
|
|
Task
|
4
|
31
|
7
|
2
|
22
|
4
|
|
Team and Social
|
0
|
36
|
22
|
0
|
26
|
20
|
|
Work and
Environment
|
1
|
14
|
3
|
1
|
9
|
3
|
|
Judgement
|
19
|
90
|
23
|
16
|
67
|
18
|
|
Other
|
0
|
8
|
0
|
0
|
3
|
0
|
recovery. Several cases of laryngeal
mask occlusion were deemed preventable by the use of a bite block. Sixteen of
the 38 events followed surgery within the airway and in this group the
reviewers noted evidence of poor anticipation and planning for management after
extubation in the
face of known problems.
Capnography and monitoring
The use of monitoring was universal
in anaesthesia cases.
In contrast to cases reported from the ICU and emergency
departments capnography appeared to be used universally for intubation and in
the operating theatre. Reviewers judged that use of capnography in the recovery
area (and
its appropriate interpretation) would have led to earlier
identification of airway obstruction in several cases. There were four
anaesthesia-related cases including two deaths
in which optimal interpretation
of capnography might have altered the clinical course. In one case, described
above, prolonged airway obstruction in recovery due to an aspirated blood clot
was diagnosed as asthma for an extended period. It was not stated whether
capnography was used. In the second case laryngeal mask misplacement in an ASA
2 patient led to severe hypoxia; intubation was performed while the patient was
peri-arrest. Intubation was difficult, as was ventilation and the capnograph
showed ‘minimal CO2’. Capnography was ‘flat’ during prolonged cardiac arrest
and this appeared to be a case of unrecognised oesophageal intubation. In the
third case a healthy patient was intubated and transferred into theatre but
became hypoxic with a
flat capnography trace. Anaphylaxis
was suspected but senior anaesthetic help promptly diagnosed the tracheal tube
in the oesophagus: the patient was transferred to ICU and made a full recovery.
In total there were three cases of unrecognised oesophageal intubation during
anaesthesia leading to one death and one case of brain damage.
Review panel analysis
Degree of harm
The outcomes ascribed to all 184
cases by the review panel are presented in Table 4.
Causal, contributory and positive
aspects of care
All reports were assessed to
identify causal and contributory factors (Table 6). Of all 184 cases the most
frequent causal and contributory factors were the patient (77% of cases),
followed by judgement (59%) and education/training (49%). Equipment/resource
and communication factors were causal or contributory in more than a quarter of
cases. Medication and work/environment were the least frequently cited factors.
Positive factors were identified in 91 cases (49%): the most frequent positive
factors being communication (22% of cases) and organisation/strategic (19%).
In the anaesthesia-related cases
similar patterns were observed (Table 6). The patient was considered causal
in
one-fifth of cases and causal or contributory factors included patient (79% of
cases), followed by judgement (62%) and education/training (47%). Organisation/
strategic factors were also causal or contributory in more than a quarter of
cases. Positive factors were identified in 65 cases (49%): the most frequent
positive factors were organisation/strategic (21% of cases) and team/social and
communication (each 15%).
Quality of airway management conduct
Of 184 airway events the review
panel assessed the airway management as good in 16% cases, mixed in 43% and
poor in 35% (Table 7). In only three of 46 events leading to death or brain
damage did the reviewers assess airway management as good and in 25 (54%) it
was assessed as poor.
■■■■■
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
35
CHAPTER 5
Results of the second phase of
NAP4: overall results and anaesthesia
Of 133 airway events during
anaesthesia airway management was assessed as good in 18% cases, mixed in 41%
and poor in 34% (Table 7).
Discussion
This project has for the first time
performed a prospective study of all major airway events occurring throughout
the four countries of the United Kingdom during anaesthesia,
in ICU and the
emergency department. It has identified a cohort of such patients, a minimum
prevalence and enabled calculation of a minimum incidence of such events. This
chapter focuses on quantitative data relating to events during anaesthesia
collected during the project. Combined with data from the matched anaesthesia
census12 we are able to estimate an incidence of such complications
occurring during anaesthesia. The incidence calculations have limitations and
these are discussed below. Of equal importance the project enables comparisons
between rates of major complications when different airways (tracheal tube,
supraglottic airway device, face mask) are used for anaesthesia. Finally, and
perhaps most importantly, the project offers the opportunity to learn from
review of a large series of such sentinel events and analysis of emerging
themes.
Table 7 Reviewers’ assessment of quality of airway management and
degree of harm. Mixed refers to an assessment of both good and poor elements
in France during 199913 analysed death certificates to identify cases, a questionnaire
was then sent to the certifiers. In the United States Li collected reports
by
using the International Classification of Diseases (ICD-10) codes to
identify anaesthesia-related complications.14 Deficiencies with
death certification in the UK have been highlighted previously in the earliest
confidential enquiry into Peri-operative deaths and problems remain.15 The use of death certification is retrospective, identifies
mortality but not morbidity, relies on accurate certification data and analysis
of individual cases is problematic. In this project we chose a prospective
methodology with a system of LRs to identify cases. This enabled us to identify
those cases that we believe most would identify as major complications, even
when the degree of harm was temporary. In addition to the NPSA classification
of severity we also assessed frequency of death and death/brain damage as this
is clinically relevant and is the outcome used by several litigation based
analyses.3,4
This study has identified 33 deaths
and 46 cases of death
or brain damage as a result of airway complications
during anaesthesia, in ICU and the emergency department over a one year period.
We calculate the incidence of serious airway complications during general
anaesthesia to be (at least)
133 per 2.9 million or one per 22,000 general anaesthetics,
death and brain damage (at least) 1 in 180,000 anaesthetics, ICU admission (at
least) 1 in 29,000 and emergency surgical airway (at least) 1 in 50,000 general
anaesthetics. Since the reports represent a timed sample it is possible that
the true incidence could be higher or lower than this figure, therefore 95%
confidence limits are provided (Table 5).
An important finding in this project
is the relative frequency of major airway events occurring with different
airway devices. Importantly comparisons between these groups are likely to be
robust as reporting rates are likely to be equal. Categorising devices as
broadly as possible it is notable that while airway events are more frequent
during anaesthesia with a tracheal tube (point estimate 83 per million) than
with, for instance, a supraglottic airway device (22 per million) the range of
incidences is not extreme and this is even more evident if only deaths and
brain damage are included: tracheal tube 9.1 per million, face mask
6.6 per million, supraglottic airway
five per million. It is not surprising that events are more frequent for
tracheal tubes as these cases include the vast majority of higher risk cases
and also the group includes intrinsically more complicated techniques (e.g.
tracheostomies, trans- tracheal ventilation etc). While some might argue that
the rates of complications of the simpler techniques should
be considerably lower, the fact we
have not demonstrated markedly higher rates of the most severe outcomes in one
particular group is reassuring in terms of the airway techniques chosen ‘en
masse’ in UK anaesthetic practice.
|
Clinical area
|
airway management
|
|
|
good
|
Mixed
|
Poor
|
not classified
|
sum
|
|
Anaesthesia
n=133
|
24
|
55
|
45
|
9
|
133
|
|
Anaesthesia
death n=16
|
3
|
4
|
8
|
1
|
16
|
|
Anaesthesia
death and brain damage n=19
|
3
|
4
|
10
|
2
|
19
|
|
All n=184
|
30
|
79
|
65
|
10
|
184
|
|
All deaths n=33
|
3
|
14
|
20
|
1
|
38
|
|
All death and
brain damage n=46
|
3
|
16
|
25
|
2
|
46
|
A detailed analysis of events which
occurred in ICU and in emergency departments is presented in Chapter 6.
While the ideal solution for
identifying the incidence of rare complications is a continuous process of
notification of critical incidents and their analysis, this is currently
impracticable. Alternatives require study of a very large population or a
prolonged period of assessment. The current project has observed complications
in the whole
of the United Kingdom over a period of one year. A similar study
of deaths related to airway complications performed
36
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
■■■■■
CHAPTER 5
Results of the second phase of
NAP4: overall results and anaesthesia
In this project aspiration (primary
airway event in 16.5% of anaesthesia-related events, secondary event in another
5%, primary event in 50% of deaths) was the single commonest primary cause of
fatality in anaesthesia events. Aspiration is the cause of litigation in about
10–15% of anaesthesia airway-related claims in America16 and the UK3 and of about one third of cases
where litigation is related to death. In Auroy’s study aspiration was the cause
of death in 83 of 131 deaths (63%). While the absolute incidence of such events
is rare, these data emphasise the importance of aspiration as a major
contributor to airway-related morbidity and mortality in anaesthetic practice.
Case review identified several cases where airway management was with a
laryngeal mask despite clear evidence of risk factors for aspiration and also
cases where rapid sequence induction was not performed in patients with bowel
obstruction. Various strategies are available to reduce the risk of aspiration
in low and high-risk patients: in NAP4 some deaths occurred without these
precautions being used.
Approximately 42% of anaesthesia
events reported had a primary airway event indicating intubation difficulty
(failed intubation, delayed or difficult intubation, CICV). Many of these cases
involved patients with head and neck cancer and airway obstruction, with
emergency surgical airway being necessary in 43% of anaesthesia cases. Poor
planning of airway strategies and failure to change routine plans despite
evidence of likely difficulty or when that plan failed were identified
problems. In both Auroy’s study and this project 13% of airway deaths were
associated with difficult tracheal intubation: put another way 87% of deaths
were not associated with difficult intubation. Auroy’s point estimate for
deaths related to difficult intubation is 21 per million with a very wide
confidence interval of (3–77). Li’s study identified failed, difficult
intubation or wrongly placed tracheal tubes to account for 2.3% of all
anaesthesia- related deaths. When the fact that the majority of airway events
occurred in elective surgery, in ASA 1–2 patients aged under 60 this project
acts as a reminder that major airway complications can occur during complex and
also apparently ‘straightforward’ routine anaesthesia.
When emergency surgical airway was
required this was performed most frequently by head and neck surgeons
performing a rescue tracheostomy, all of which were successful.
Cricothyroidotomy was the rescue technique of choice for anaesthetists but
approximately 65% of these attempts failed to secure the airway. As two thirds
of emergency tracheostomies were performed in semi- controlled conditions the
cricothyroidotomies likely did represent a greater proportion of ‘in extremis’
cases. As NAP4 studied events with poor outcomes it is possible that a
disproportionate number of successful rescue cannula cricothyroidotomies were
not reported. Even accepting these caveats, the high failure rate of this
technique is
■■■■■
a cause for concern. Whether this is
due to failures of training, use of inappropriate equipment, equipment design
problems or technical failures during use requires further exploration and
research. Anaesthetists might usefully study this area and ensure their
competence with both cannula and surgical techniques.
Forty-two percent of all patients
notified to NAP4 were obese. Obesity was identified in 40% of anaesthesia cases
and cachexia in 11%. The incidence of adult obesity in the UK in 2008 was
reported to be 24.5%17 and although we
do not know the
incidence of obesity or cachexia in the surgical population both groups are
likely over-represented. An excess of cachectic patients is accounted for by a
significant number of events occurring in patients with recurrent (sometimes
pre-terminal) head and neck cancers. In contrast the excess of obese patients
underscores the fact that obese patients are at increased risk of an adverse airway
event. Reasons for this include mechanical difficulty in securing the airway
(mask ventilation,18 perhaps tracheal intubation19 and emergency surgical airway), increased
risk of aspiration, increased risk
of airway obstruction during difficulty, and accelerated speed and extent of
oxygen desaturation during airway obstruction.20 Of the
53
anaesthesia-related cases reported, mechanisms of injury and outcomes were
notably similar to the non-obese reports. The fact that airway events occurred
in obese patients who might have had their surgery performed under regional
anaesthesia, but also after attempted regional anaesthesia or sedation failed,
illustrates that these patients are a major challenge for all anaesthetic
techniques and anaesthetists. In view of the trends in population obesity in
developed countries the number of patients at risk of such events due to
obesity is almost certain to increase.
In terms of timing of events it was
notable that events occurred at all phases of the anaesthetic process. While
induction was the phase when most (52%) events occurred a significant minority
occurred during emergence (16%) and in (or during transfer to) the recovery
area (14%). The latter phase being particularly dangerous as the anaesthetist
may be neither present nor immediately available to respond to an emergency.
In the cases of tracheal obstruction
or tube misplacement, capnography and correct interpretation might have led to
a change in clinical management and outcome. Each of the cases serves to remind
that absence of expired carbon dioxide (i.e. a flat capnograph) indicates lack
of ventilation. When this occurs in an intubated patient, even during cardiac
arrest the possibility of tracheal tube occlusion, tracheal obstruction or
oesophageal intubation must be excluded before treating other causes. The
capnograph trace is not flat in a correctly intubated patient during CPR and
this is discussed in depth in the companion paper.10
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
37
CHAPTER 5
Results of the second phase of
NAP4: overall results and anaesthesia
Cases of high airway pressure and
ineffective ventilation with inadequate capnograph trace were erroneously
attributed to asthma or anaphylaxis. Endoscopic examination of the tracheal
tube would have assisted earlier diagnosis of intraluminal obstruction or
oesophageal intubation.
The AAGBI recently published a
statement recommending that ‘Continuous capnography should be used in the
following patients, regardless of location within the hospital:
▪
those whose tracheas are intubated
▪
those whose airways are being
maintained with
supraglottic or other similar airway devices.’21
The statement specifically includes
recovery rooms. Capnography in recovery would likely have mitigated several
events reported to NAP4. Other potential methods of improving diagnosis of
airway obstruction in recovery include nursing education, observation of
‘t-bag’ movement to monitor respiration and the presence of an anaesthetist in
the recovery area.
Analysis of reviewer’s opinions indicates that intrinsic patient
features contributed to the airway event in more than three quarters of
anaesthesia events. The commonest extrinsic (care-related) contributory factors
were judgement and training. After excluding the patient as a contributory/
causal factor the ratio of contributory/causal factors to positive factors was
approximately 2.5 for all cases and
for anaesthesia cases. This reinforces the
finding that reviewers assessed airway management to have elements that were
poor in three quarters of anaesthesia events
and in more than 80% of deaths. A
caveat is that the
NAP4 process was good at identifying procedural and
narrative events but was not, because of its design, suited for in-depth
analysis of human factors. Despite this, and limitations described below, the
assessment was that in many cases better planning, better knowledge, better
judgement or better communication, amongst other factors would likely have
mitigated the events or even prevented some. Amongst the human factors most
frequently identified were elements of poor communication, poor teamwork, poor
leadership and task fixation.
There are numerous positive aspects to the findings in this
report and space only allows a brief comment. Perhaps most important is that
all UK NHS hospitals took part and individual anaesthetists were willing to
report these high impact events. It is also notable that most anaesthesia cases
were managed in the presence of a consultant anaesthetist and often by several
senior anaesthetists working together. When problems arose a call for
assistance was usual (73%), the person responding to the request was a
consultant in 85% of cases and assistance
arrived in less than four minutes in
79% of cases. These findings suggest that appropriately senior anaesthetists
manage many difficult cases and that anaesthetic departments in UK NHS
hospitals generally have a culture of colleague assistance and structures that
enable prompt assistance in the event of a crisis. This is reinforced by the
reviewers’ analysis of cases which indicated that the factors most commonly
identified as ‘positive’ in anaesthesia cases were organisation/strategic
followed by communication and team/social. This report has necessarily focused
on deaths and brain damage but each of the non-fatal cases reported to NAP4 can
be considered a near death. The
133 reports of events during
anaesthesia may well be a significant underestimate. As more than one
anaesthetist
is generally involved in each case, as many as 1,000 anaesthetists
may be involved with such events each year (approximately one event for a
consultant every six years). It is a tribute to the specialty that so few
patients came to serious harm and few died but these were still very serious
events and to individual anaesthetists these will probably be events that they
will never forget.
limitations
One of the aims of this project was
to determine the incidence of major complications of airway management in
anaesthesia. This has been challenging, both in determining an accurate
denominator and in establishing a numerator, because we know there will have
been cases that were
not reported. We identified 133 major events including 16
deaths and three cases of brain damage related to airway complication of
anaesthesia. Accepting the limitations,
we are able to calculate a point
estimate of this incidence and a confidence interval surrounding it. Our
estimate is of 46 events per million (95% Confidence Interval 38–54) and with 12%
of these leading to death a fatality rate of 5.6 per million (CI 2.8–8.3).
Auroy’s study identified ‘airway deaths’ of 20 per million (CI 7–36): while
these confidence limits overlap those of Auroy are wide and suggest a higher
rate of complications than the current study.13
The project has several limitations.
It is likely that not
all cases were reported but we cannot know how many,
or
indeed if any were missed. We tried to maximise reporting but acknowledge that
many factors may have contributed to under-reporting. There may be a
personal
or organisational reluctance to release information if there is an
ongoing investigation or if litigation is anticipated. Furthermore after facing
challenging events some anaesthetists will have suffered personal trauma. Cases
took up to a year after the event to be fully reported. Our analyses of
reporting patterns by institution and by time are compatible with complete
reporting but do not guarantee it. Our incidence calculations are based on
reported
cases, however statistical advice and analysis indicated
the true
incidence may be up to four-fold higher. In this
38
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
■■■■■
CHAPTER 5
Results of the second phase of
NAP4: overall results and anaesthesia
project aspiration of gastric
contents was the cause of death in eight patients giving an incidence of 1 in
360,000 anaesthetics (95% confidence interval 1 in 212,000–1.1 million). Other
large studies have reported rates of fatal aspiration associated with
anaesthesia from 1 in 45,00022
to 1 in 240,00023 with one study identifying no cases in 198,000 paediatric
anaesthetics.24 These data suggest, but cannot confirm under-reporting to the
NAP4 project and cannot quantify it. Comparisons between NAP4 data and those
from studies performed in other countries, several decades ago, with different
methodology should be treated with caution.
We are not aware of any better
estimates of anaesthesia airway-related morbidity by other researchers. As we
recruited LRs in 100% of NHS hospitals in the UK and all LRs returned data to
the project we believe our effort approaches the best achievable with current
methods. Our explicit description of how many cases we estimate may have been
missed enables readers to interpret the data in the knowledge of these
limitations.
There were several cases where the
decision to include
or exclude was not clear-cut. One case of fatal aspiration
which occurred while an anaesthetist who had sedated
a patient performed a
spinal anaesthetic was excluded;
the level of sedation was unknown and the
primary aim
of the project was not to study complications of sedation.
In
contrast two cases that initially took place under
local anaesthesia or
sedation were included. In one an anaesthetist administered sedation for
endoscopy including oesophageal and pyloric dilation before aspiration
occurred, the patient died. In the other, tonsillar biopsy under local
anaesthesia with ‘deep sedation’ was complicated by profuse bleeding. The
anaesthetist attempted to rescue
the airway but intubation failed and an
emergency airway was required, this patient made a full recovery. These cases
likely fall under the umbrella of ‘managed anaesthesia care’. They were
considered to be consistent with the sorts of cases the project was designed to
study.
A final limitation is inherent when
expert panel review
is used to ‘judge cases’. We relied on submitted
questionnaires and did not have access to case-notes nor the facility to speak
to the clinicians involved. Despite this we believe our review process was
robust. It can be summarised as a structured implicit review performed
in teams. Pitfalls of retrospective
case review include variation in reviewer opinion, outcome bias,25 hindsight bias,26 and a bias we will call ‘consensus
bias’. The latter bias occurs because teams reviewing cases often reach
internal agreement but disagree with other teams.27 While it
is impossible to overcome all these biases we made the following efforts to do
so. The review panel was educated in hindsight and outcome bias and at each
meeting the reviewers were reminded of these biases,
■■■■■
definitions of which appeared on the
sheets categorising outcomes. Each case was reviewed by two teams enabling an
exploration of ‘between group disagreement’ to balance the tendency for ‘within
group agreement’. Guidelines and recommendations published by other
organisations were used in the review process where considered appropriate.
When judging case conduct against guidelines the review panel attempted to
ensure they were applicable, based
on high quality evidence, up-to-date
and specific to the individual case.
Conclusions
Airway management during anaesthesia
is associated with serious complications and these are rare. Optimistically the
incidence of complications resulting in death is 16 in 2.9 million an incidence
of one death per 180,000 general anaesthetics. Pessimistically, based on the
assumptions discussed, if only 25% of reports have been received
this figure could rise to one death
per 45,000 general anaesthetics.
Important findings related to
anaesthesia cases in this project.
1 More than
half of patients were male, ASA 1–2, aged under 60 and most events occurred
during elective surgery under the care of anaesthetic consultants.
2 Aspiration
was the most frequent cause of anaesthesia- airway-related mortality.
3 Obese
patients were disproportionately represented.
4 Obstructing
airway lesions generated a large number of complications, many reports showed
evidence of poor planning of primary and rescue techniques.
5 Cricothyroidotomy
by anaesthetists was associated with a high rate of failure.
6 One in
four events occurred at the end of anaesthesia or in the early recovery room.
7 Omission
or incorrect interpretation of capnography led to undiagnosed oesophageal
intubation.
8 Elements
of poor management were observed in the majority of airway complications and
most deaths.
Detailed analysis of the reports of
individual airway events during anaesthesia will contribute to our understanding
of
events causing patient harm and should enable improvements in the quality of
care delivered.
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
39
CHAPTER 5
Results of the second phase of
NAP4: overall results and anaesthesia
References
.
1 Utting JE. Pitfalls in anaesthetic practice. Anaesthesia
1987;59:877–890.
.
2 Gannon K. Mortality associated with anaesthesia.
A case review study. Anaesthesia 1991;46:962–966.
.
3 Cook TM, Scott S, Mihai R. Litigation related to
airway and respiratory complications of anaesthesia: an analysis of claims
against the NHS in England 1995–2007. Anaesthesia 2010;65:556–563.
.
4 Caplan RA et al. Adverse respiratory events in
anesthesia: A closed claims analysis. Anesthesiology 1990;72:828–833.
.
5 Gene N et al. Management of the Difficult Airway.
A Closed ClaimsAnalysis. Anesthesiology2005;103:33–39.
.
6 Special Article. Practice Guidelines for
Management of the Difficult Airway. An Updated Report by the American Society
of Anesthesiologists Task Force on the Management of the DifficultAirway. Anesthesiology2003;98:1269–1277.
.
7 Brennan TA et al. Incidence of adverse events and
negligence in hospitalized patients. Results of the Harvard Medical Practice
Study I. New Eng J Med 1991;324:370–376.
.
8 Studdert DM et al. Negligent care and malpractice
claiming behavior in Utah and Colorado. Medical Care 2000;38:250–
260.
.
9 Smith AF, Mahajan R.P. National critical incident
reporting: improving patient safety. Br J Anaesth 2009;103:623–625.
.
10 Cook TM et al. Major complications of airway
management in the UK: results of the 4th National Audit Project of the Royal
College of Anaesthetists and the Difficult Airway Society. Part 2 Intensive
care and Emergency Department. Br J Anaesth (January 2011) in press.
.
11 McLaughlan C. The Royal College of Anaesthetists
census report 2007. RCoA Bulletin 2008;50:2577–2578 (www.rcoa.
ac.uk/docs/Censusreport-final.pdf).
.
12 Woodall NM, Cook TM. A national census of airway
management techniques employed during anaesthesia in the UK: results of the
first phase of the 4th National Audit Project at the Royal College of
Anaesthetists. Br J Anaesth 2010; e-published December 2010 – doi:
10.1093/bja/aeq339.
.
13 Auroy A et al. Mortality related to anaesthesia
in France: analysis of deaths related to airway complications. Anaesthesia 2009;64:366–370.
.
14 Li G et al. Epidemiology of anesthesia-related
mortality in the United States 1999–2005. Anesthesiology 2009;110:759–765.
.
15 Tuffin R et al. A review of the accuracy of
death certification on the intensive care unit and the proposed reforms to the
Coroner’s system. J Inten Care Society 2009;10:134–137.
.
16 Domino KB et al. Airway injury during
anaesthesia. Anesthesiology 1999;91:1703–1711.
.
17 Statistics on obesity physical activity and
diet: England, 2010. The Health and Social Care Information Centre, 2010
(ISBN:978- 1-84636-382-5) (www.ic.nhs.uk/webfiles/publications/
opad10/Statistics_on_Obesity_Physical_Activity_and_Diet_ England_2010.pdf,
accessed 2 January 2011).
18 Kheterpal S et al. Incidence and predictors of
difficult and impossible mask ventilation. Anesthesiology 2006;105:885–
891.
19 Kristensen MS. Airway management and morbid obesity. Eur
J Anaesthesiol 2010;27:923–927.
20 Farmery AD, Roe PG. A model to describe the rate of
oxyhaemoglobin desaturation during apnoea. Br J Anaesth 1996;76:284–291.
21 Safety Statement Capnography outside the Operating
Theatre. AAGBI (www.aagbi.org/aboutaagbi/pressoffice/
statements/aagbi_safety_statement_capnography_jan09. htm, accessed 2 January
2011).
22 Olsson GL, Hallen B, Hambraeus-Jonzon K. Aspiration
during anaesthesia: a computer-aided study of 185,358 anaesthetics. Acta
Anaesthesiol Scand 1986;30:84–92.
23 Harrison GG. Death attributable to anaesthesia. A ten
year survey (1967–1976). Br J Anaesth 1978;50:1041–1046.
24 Tiret L et al. Complications related to anaesthesia in
infants and children. A prospective survey of 40,240 anaesthetics. Br J
Anaesth 1988:61:263–269.
25 Caplan RA, Posner KL, Cheney FW. Effect of outcome on
physician judgements of appropriateness of care. JAMA 1991;265:1957–1960.
26 Henriksen K, Kaplan H. Hindsight bias: outcome
knowledge and adaptive learning. Qual Saf Health Care 2003;122(supp
2):46–50.
27 Crosby E. Medical malpractice and anesthesiology:
literature review and role of the expert witness. Can J Anaesth 2007;54:227–241.
40
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
■■■■■
CHAPTER 5
Results of the second phase of
NAP4: overall results and anaesthesia
Dr Tim Cook Dr nick woodall
This chapter is based on the
original paper reporting the results of the naP4 project.
it appears here by kind permission
of the editor-in-Chief and board of the British Journal of anaesthesia where it
was first published.
Cook TM et al. Major complications of airway management
in the UK: results of the 4th National Audit Project of the Royal College of
Anaesthetists and the Difficult Airway Society. Part 2 Intensive care and the
emergency department. Br J Anaesth 2011.
Introduction
Active airway management takes place
most frequently
in anaesthetic practice. However, the same skills and
techniques are often required outside the operating theatre. Several studies of
airway management outside
the operative theatre have identified higher rates of
complications including failed intubation, oesophageal intubation, hypoxia and
cricothyroidotomy. These include studies in Intensive Care1–4 and emergency departments.4–8 Differences in
factors such as case mix, availability of
skilled and trained staff, levels of
assistance and working environment all likely contribute. Recent data from
analysis of the National Reporting and Learning System (NRLS) of the National
Patient Safety Agency (NPSA) indicated that Intensive Care may be an area where
airway complications are relatively frequent,9 but the data were
limited by the nature of NRLS reporting, which numerically focuses on low
impact events.9,10
The 4th National Audit Project of
the Royal College of Anaesthetists and Difficult Airway Society (NAP4) had
the
primary aim of identifying the incidence of major complications of airway
management during anaesthesia. At an early stage in planning NAP4 it was
decided that it would be important to study similar complications in the
environments of Intensive Care Units (ICU) and emergency departments for the
reasons stated above. This chapter describes the major findings of this section
of the NAP4 project.
This chapter should be read in
conjunction with Chapters 3 and 5.11
Professor
Dr Jane harper Jonathan Benger
Methods
The full methodology of the NAP4
project is described in Chapter 3.
Results
Agreement to participate and
appointment of a LR was confirmed in all 309 hospitals by September 2008.
In
total 286 anaesthesia LRs were appointed with some representing more than
one hospital. In addition 118 ICU LRs (for 253 UK ICUs: 47%) and 115 emergency
department LRs (for 239 major UK emergency departments: 48%) were recruited.
Anaesthesia LRs were encouraged to report cases from ICU and the emergency
department when there were no additional LRs.
Complications reported
A total of 286 cases were reported
to the RCoA lead or discussed with the moderator. Seventy-nine reports
were
withdrawn after discussion with the moderator or the reporter reviewed the
inclusion criteria sent by the RCoA lead: 207 cases were reviewed by the review
panel. During the review process additional information, using the methods described
in Chapter 3, was requested from the reporters of 12 of the cases. After final
review 184 reports met the inclusion criteria. Of the 184 reports 133
complicated the management of anaesthesia, 36 occurred in patients on ICU and
15 in the emergency department.
Demographic data
Of the ICU cases the male: female
ratio was 21:15 (58% male), 22% were ASA grade 1–2 and 61% aged under 60 (see
Table 1). In ICU 19 patients were receiving invasive ventilation, eight
non-invasive ventilation, eight were not receiving mechanical ventilation prior
to the airway event: in one case this information was not provided. Ninety-four
percent were receiving supplemental oxygen before the event and in 35% this was
a FiO2 of 0.6 or more. Thirteen had organ failures other than respiratory
and nine were receiving vasoactive drugs or continuous renal replacement
therapy. A BMI of >30 kg.m-2 or obese body habitus was recorded in 47% of ICU cases and a BMI
of <20 kg.m-2 or cachexia in 6%. While 24% of
anaesthesia events took place out of hours (18.01–08.00) the figure for ICU was
46% of events for which a time was recorded. Although consultants were present
for 58% of all events, there was a notable difference between events in hours
(80%) and out
■■■■■
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
41
CHAPTER 6
Results of second phase of
NAP4: ICU and the emergency department
of hours (36%). Several events were
managed by doctors who would not be expected to have airway expertise because
of lack of seniority (e.g. specialist trainee (ST) year 2) or primary specialty
(e.g. ST2 in medicine).
Of the emergency department cases
the male: female ratio was 10:5 (67% male), 40% were ASA grade 1–2 and 80% aged
under 60 (see Table 1). A BMI of >30 kg.m-1 or obese body
habitus was recorded in 46% of emergency department cases and a BMI of <20
kg.m-1 or cachexia
in 7%. Fifty-three percent of events
took place ‘out of hours’. All cases except three involved attempts at tracheal
intubation, the exceptions being face mask anaesthesia
for cardioversion and
two surgical airways for airway obstruction. In 11 cases (73%) airway
management
was performed by an anaesthetist and in eight (53%) a consultant.
Anaesthetist involvement fell from 6/7 during the day (0801–1800) to 5/8 out of
hours and consultant involvement was 4/7 in-hours and 4/8 out of hours.
Several
events were managed by doctors who would
not be expected to have airway
expertise, including two ICU trainees with minimal anaesthetic experience
and
one Acute Care Common Stem trainee with five months’ anaesthetic
experience. In a further three cases the anaesthetist present at the start of
the airway event was a year 3 specialist trainee, and in eight events no
consultant was present at the start of the airway event.
inclusion criteria and event outcomes
The inclusion criteria indicated by
reporters are presented in Table 1. The final outcome of events is presented,
both focusing on outcomes of death and brain damage and by NPSA classification
of severity of harm, in Table 2.
Death
Death resulting from an airway
problem was the inclusion criterion for 33 reports: 16 occurred in ICU and
three
in the emergency department (Table 1). Three further cases resulted in
late deaths, two in ICU and one in the emergency department. In total there
were 38 deaths attributable to an airway event, 18 on ICU and four in the
emergency department. Hypoxia was the common theme in deaths caused by an
airway problem in both ICU and the emergency department. Death rate for cases
in ICU was 18/36 (50%) and in the emergency department 4/15 (27%).
Table 1 incident reports classified 1) by asa grade and type
of event,
2) by age and type of event, 3) by inclusion criteria provided by the reporter.
More than one inclusion criterion could be chosen. note that some deaths were
considered by the review panel not to be causally related to the event, in
other cases patients reported with an inclusion criterion of brain damage
either made a full recovery at the time of reporting or died. Therefore figures
in this Table do not exactly match final outcomes in Table 2
|
all cases (n=184)
emergency iCu (n=36)
department
(n=15)
|
|
ASA
|
|
1 2612
|
|
2 6274
|
|
3 59145
|
|
4 29133
|
|
5 310
|
|
Not recorded 5
0 1
|
|
Age
|
|
<10 10 1 1
|
|
11–20 8 2 0
|
|
21–40 39 6 7
|
|
41–60 56 11 4
|
|
61–80 60 14 2
|
|
>80 10 2 1
|
|
Not recorded 1
0 0
|
|
Reporter
provided inclusion criteria
|
|
Death 33 16 3
|
|
Brain Damage 13
6 1
|
|
ESA 751011
|
|
ICU admission*
122 12 10
|
|
(sum) (243)
(44) (25)
|
*prolongation of stay in the case of patients already in
ICU
42
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
■■■■■
CHAPTER 6
Results of second phase of
NAP4: ICU and the emergency department
Table 2 final outcome (1) narrative outcome, (2) nPsa classification
(see Chapter 3)
iCu admission
Of 122 cases included in NAP4
because of ICU admission or prolongation of ICU stay, 12 arose in patients
already on ICU and ten in emergency department cases. The commonest reasons for
prolongation of stay on ICU after an airway event were failure to awaken in
five, aspiration of gastric contents or blood in four and airway swelling in
two. The commonest reasons for emergency department cases to be admitted to ICU
were management of airway swelling/trauma in four, failure to awaken in three
and aspiration in two.
Primary airway problem
In the ICU tracheostomy-related
events were the most frequently occurring problem (n=18, 50%) (Table 3). Next
most frequent was failed intubation or tracheal tube misplacement (including
unrecognised oesophageal intubation and inadvertent extubation). Displacement
of an existing tracheostomy or standard tracheal tube combined accounted for 18
events and half of all cases of death or brain damage. These events occurred
most frequently in obese patients and during patient movement, sedation holds
(e.g. sudden awakening and coughing or manually removing a tube) or airway
interventions (e.g. tracheal suction or nasogastric tube placement). Of all
tubes that became dislodged, 13 were recorded as taped (ties, Velcro straps),
two sutured and three both taped and sutured. There were three unrecognised
oesophageal intubations and two led to death (a further fatal unrecognised
oesophageal intuation was a secondary event). Displacement or obstruction of
tracheostomies and difficult intubation required a fibrescope on several
occasions and delays in accessing one was a recurrent problem, in some cases
associated with harm.
Events in the emergency department
were predominantly related to tracheal intubation and included delayed or
failed intubation, unrecognised oesophageal intubation, the CICV scenario,
aspiration and perforation of the trachea with
a bougie (Table 3). The two
unrecognised oesophageal intubations led to death. Airway management in both
these cases was undertaken by a non-anaesthetist intensive care doctor, one
junior and one senior, the latter with limited anaesthetic experience. The case
of significant airway trauma occurred during an uneventful intubation by an
emergency physician.
Paediatrics and obstetrics
There were no cases reported from
ICU or the emergency department that involved pregnant women.
One event occurred in ICU in a child
under ten years: a dysmorphic neonate required multiple attempts to intubate
and the tracheal tube was then repeatedly displaced. Intubation became
impossible and attempts were made to
|
|
all cases (n=184)
|
iCu (n=36)
|
emergency department
(n=15)
|
|
Final
outcome (narrative)
|
|
|
|
|
Death
|
38
|
18
|
4
|
|
Brain damage
|
8
|
4
|
1
|
|
Other partial
recovery
|
10
|
3
|
1
|
|
Full recovery
|
124
|
9
|
9
|
|
Unrelated death
|
4
|
2
|
0
|
|
Final
outcome (NPSA definitions)
|
|
|
|
|
Death
|
38
|
18
|
4
|
|
Severe
|
10
|
5
|
0
|
|
Moderate
|
126
|
12
|
11
|
|
Low
|
7
|
1
|
0
|
|
None
|
3
|
0
|
15
|
Brain damage
In 13 patients brain damage was
recorded as an inclusion criterion, six in reports of events on ICU and one in
the emergency department (Table 1). After excluding those who died or recovered
there were four cases of persistent non-fatal brain damage in ICU and one in
the emergency department. Combined rate of death and brain damage for ICU cases
was 22/36 (61%) and in the emergency department 5/15 (33%).
emergency surgical airway
An attempt at emergency surgical
airway, either tracheostomy or cricothyroidotomy, was reported as an inclusion
criterion in 75 cases (Table 1): case review identified 80 attempts in 184
reported cases (43%).
Twelve attempts took place on ICU
(33% of all ICU cases) with three failing to rescue the airway, a failure rate
of 25%. Five needle cricothyroidotomies were attempted in ICU, three of which
failed. One patient with successful surgical airway died and one suffered
persistent brain damage; two patients with failed placement of an emergency
surgical airway died.
Ten emergency surgical airways were
placed in the emergency department (67% of emergency department cases) with no
total failures. However, in all three cases where a needle cricothyroidotomy
was attempted this failed and had to be replaced by a surgical or percutaneous
technique. Of the ten patients requiring a surgical airway in the emergency
department two died and one suffered persistent brain damage.
■■■■■
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
43
CHAPTER 6
Results of second phase of
NAP4: ICU and the emergency department
transfer the patient to theatre for
a surgical tracheostomy but the airway was again lost during transfer and the
patient died. There was one paediatric event reported from the emergency
department: a case of inadvertent oesophageal intubation in an infant. During
cardiac arrest a flat capnography trace was not recognised as indicating
‘non-intubation’. The patient died.
Table 3 Primary reported airway event
36% (n=13) (Table 5). In the
emergency department airway management was assessed as good in 13% (n=2) cases,
mixed in 33% (n=5) and poor in 46% (n=7) (Table 5). Airway management was
assessed as poor in almost half of ICU deaths and all emergency department
deaths.
Discussion
This project has performed a
prospective study of major airway events occurring throughout the United Kingdom
during anaesthesia, in Intensive Care and the emergency department for the
first time. In-depth structured review
of these cases has identified specific
issues and recurrent themes. While such a study will be ranked low in a
hierarchy of research quality it is likely to have considerable clinical
relevance and importance.
There is much that could be
discussed but this discussion is structured in three sections.
▪
What have we observed?
▪
What do we learn from these
observations?
▪
What can be done to improve airway
management in the environments of ICU and the emergency department?
what have we observed?
We have observed that although ICU
was the setting for fewer than 20% of notified events almost half of deaths
occurred there. More than 60% of events reported from ICU led to death or brain
damage (compared to 14% in anaesthesia). While it is not surprising that ICU
patients frequently had a high ASA grading, multi-organ failure
and were
receiving high inspired oxygen fractions, the
high rate of obesity (approaching
50%) of patients experiencing major airway complications is a new and notable
finding. Events in the ICU in obese patients led
to death or permanent brain
damage more often than events in non-obese patients (12 of 17 obese vs ten of
19 non-obese): this contrasts to anaesthesia, where events in obese patients
were not associated with poorer outcomes than in non-obese patients. Primary
events leading to complications were more likely than anaesthesia events to
involve failed intubation or problems with tracheostomies. These events were
more likely than anaesthesia events to occur out of hours and to be managed by
inexperienced staff. NAP4 identified several cases where management of
intubation was by staff who were inadequately experienced and when problems
arose they were not managed in a logical or recognised manner. Issues with
equipment
arose frequently and included non-availability, lack of training
in the use of equipment and failure to consider using the right equipment. When
rescue techniques were used (face mask ventilation, laryngeal mask ventilation,
and cricothyroidotomy) these all had relatively high rates of failure. Issues
of preparedness were also identified
|
iCu n=36
|
|
|
Tracheostomy
related problems
|
14
|
|
Tracheal tube
misplacement/displacement
|
7
|
|
Failed
intubation
|
6
|
|
Oesophageal
intubation
|
4
|
|
CICV – the
can’t intubate can’t ventilate scenario
|
2
|
|
latrogenic
airway trauma
|
2
|
|
Problems at
time of extubation
|
1
|
|
emergency department
n=15
|
|
|
Failed
intubation
|
7
|
|
Difficult or
delayed intubation
|
1
|
|
Oesophageal
intubation
|
2
|
|
CICV – the
can’t intubate can’t ventilate scenario
|
2
|
|
latrogenic
airway trauma
|
1
|
|
Aspiration of
gastric contents
|
2
|
Review panel analysis
Degree of harm
The outcomes ascribed to all ICU and
emergency department cases by the review panel are presented in Table 2.
Causal, contributory and positive
aspects of care
Causal and contributory factors were
identified in all 36 ICU cases (Table 4). The most frequent causal and
contributory factors were patient-related (69% of cases), followed by
education/training (58%), judgement (50%), equipment/ resource (36%) and
communication (31%). Positive factors were identified in 19 cases (54%): the
most frequent positive factors were communication (36% of cases) and
organisation/strategic (19%).
Causal and contributory factors were
identified in all 15 emergency department cases (Table 4). The most frequent
causal and contributory factors were patient-related (73% of cases), followed
by judgement (57%), education/training (40%) and task (33%). Positive factors
were identified in
8 cases (53%), the most frequent
positive factor being communication (33% of cases).
Quality of airway management conduct
Reviewers assessed airway management
in ICU cases as good in 11% of cases (n=4), mixed in 52% (n=19) and poor in
44
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
■■■■■
CHAPTER 6
Results of second phase of
NAP4: ICU and the emergency department
Table 4 factors assessed by review panel to contribute or cause events
and factors indicating good practice. for definitions of factors listed see
Chapter 3
|
factors
|
all cases (n=184)
|
iCu (n=36)
|
eD (n=15)
|
|
|
Causal
|
Contributory
|
Positive
|
Causal
|
Contributory
|
Positive
|
Causal
|
Contributory
|
Positive
|
|
Communication
|
4
|
38
|
40
|
2
|
9
|
13
|
0
|
3
|
5
|
|
Education and
Training
|
12
|
77
|
17
|
2
|
19
|
2
|
0
|
6
|
2
|
|
Equipment and
resources
|
2
|
46
|
21
|
0
|
13
|
4
|
0
|
4
|
1
|
|
Medicines
|
0
|
31
|
5
|
0
|
7
|
0
|
0
|
4
|
0
|
|
Organisation
and strategic
|
1
|
42
|
35
|
0
|
7
|
7
|
0
|
0
|
0
|
|
Patient
|
37
|
103
|
1
|
6
|
19
|
0
|
3
|
8
|
0
|
|
Task
|
4
|
31
|
7
|
0
|
6
|
2
|
2
|
3
|
1
|
|
Team and Social
|
0
|
36
|
22
|
0
|
7
|
1
|
0
|
3
|
1
|
|
Work and
Environment
|
1
|
14
|
3
|
0
|
4
|
0
|
0
|
1
|
0
|
|
Judgement
|
19
|
90
|
23
|
3
|
15
|
4
|
0
|
8
|
1
|
|
Other
|
0
|
8
|
0
|
0
|
3
|
0
|
0
|
2
|
0
|
and included failures to identify
patients at risk of complications, failures to formulate a plan for critical
events in these patients and failure to ensure that such a plan could be
carried out (i.e. right equipment and right expertise immediately available).
The assessors judged airway management in the ICU to be good less frequently
than in either anaesthesia or the emergency department.
Observations in the emergency
department were similar, with a high proportion of events occurring out of
hours and without consultants present; the primary airway problem was
predominantly failed or problematic intubation and outcomes were similar to
those in ICU, though less severe. Several reports suggested failure of
preparation, failure to follow standard practices for airway protection or
airway rescue in cases of difficulty. Emergency surgical airway was required in
two-thirds of cases, higher than during anaesthesia or in the ICU, and in all
cases was ultimately successful, also higher than other settings.
An observation in both ICU and the
emergency department was of unrecognised oesophageal intubation. In total there
were six leading to five deaths (23% of deaths in these areas). All were
performed by clinicians with very limited airway experience. Capnography was
not used in five cases and in one case it was used but a flat capnograph trace
was misinterpreted as being ‘due to cardiac arrest’.
In both groups, there was a high
failure rate of needle cricothyroidotomy. Of eight attempted in ICU and the
emergency department, six failed (75%) and the airway was rescued either with a
surgical approach (open or percutaneous tracheostomy) or with other
non-invasive
■■■■■
techniques. Direct surgical
approaches to the trachea had high success rates.
what do we learn from these observations?
In both settings it must be accepted
that patients may present with complex conditions which are intrinsically
‘high-risk’: in ICU because of critical illness and oxygen dependency and in
the emergency department because of underlying pathology or injury that has
precipitated their admission. An American Society of Anesthesiologists’ Closed
Claims Project (ASACCP) study identified claims related to difficult airway
management outside the operating theatre to be considerably more likely to lead
to fatal outcomes than in the operating theatre.13 Mort’s
study of more than 10,000 emergency intubations outside the operating theatre
found multiple attempts at intubation to be associated with dramatic increases
and
high rates of hypoxaemia (11.8%
versus 70%), regurgitation of gastric contents (1.9% versus 22%), aspiration
(0.8% versus 13%), bradycardia (1.6% versus 21%) and cardiac arrest (0.7%
versus 11%).3 For these reasons the staffing and equipment in both settings
must be such that airway management can be timely, skilled and where necessary
utilise highly advanced techniques. This requires planning and communication.
In ICU planning should recognise
that intubation sometimes fails,
that tracheal tubes and tracheostomies will inadvertently fall out and that all
these events are more likely to occur in obese patients. Tracheal tube and
tracheostomy displacement in ICU was repeatedly reported after patient movement
or patient interventions and this has been reported before.9 Similarly delayed diagnosis
of displacement, in the absence of
capnography has been reported before9 and was reported repeatedly in this
project.
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
45
CHAPTER 6
Results of second phase of
NAP4: ICU and the emergency department
Failed intubation or difficult
intubation contributed to many events on ICU and the emergency department.
Failure to identify potential difficulty, to have a strategy for failure (plan
B, plan C), to assemble the correct equipment and intubation by inappropriately
inexperienced personnel contributed to numerous events. These observations also
applied to patients specifically admitted to an ICU for airway monitoring and
management. Reviewer assessments frequently identified system, organisational
and human factor deficiencies. In
a recent study by Jaber and
colleagues, implementation
of a ten-point ICU intubation management protocol
(‘care bundle’) led to a 30–60% reduction in complications.14 There are various interpretations of this study but it is
notable
that the bundle included pre-oxygenation with continuous positive
airways pressure, presence of two operators, rapid sequence induction,
capnography, and early administration of vasopressors if needed. Such a
protocol, supported by
a checklist is attractive in the light of this study and
other checklist-driven successes in ICU.15
In the emergency department
predictable airway emergencies include trauma intubations, stridor, inhaled
foreign bodies and other causes of airway obstruction. The rate of difficult
intubation in the emergency department may be as high as 8.5%, and the need for
an emergency surgical airway as high as 0.5%.5–8 Knowledge
of likely scenarios should drive preparedness of personnel, equipment,
communication channels and policies. Benger and Hopkinson’s survey12 identified that approximately 20,000 rapid sequence inductions
of anaesthesia (RSIs)
are performed in UK emergency departments per year
and
therefore an average size emergency department will perform RSI approximately
every four or five days with 80% of these performed by anaesthetists, many of
whom are trainees. In this project we identified avoidable harm,
including death, caused by airway
trauma or oesophageal intubation that occurred during airway management by
clinicians with limited airway management experience. The implications are that
emergency physicians undertaking these procedures need specific training to
establish
and maintain their skills and that
anaesthetists and ICU doctors need to understand the particular requirements
and difficulties of airway management in the emergency department. Channels of
communication between
the emergency department and
anaesthesia or ICU departments need to be well established to ensure prompt
attendance by an appropriately skilled senior clinician.
Diagnosis of oesophageal intubation
was hampered by
lack of capnography. The current situation in ICU and the
emergency department can be compared to the 1980s
when capnography was not
universally used for intubation
in anaesthesia. The ASACCP identified numerous
cases of litigation after oesophageal intubation: 16 delays in diagnosis of
more than five minutes were almost universal, auscultation routinely gave false
positives, cyanosis was often absent and it was cardiovascular disturbance or
collapse that alerted clinicians to the problem in over 80% of cases. The
authors commented on ‘preconceived notions of likelihood’, ‘reflex clinical
behaviours’, ‘conflicting environmental data’, ‘the inherent limitations of
diagnostic tests’ and ‘the potential
for a rapid and poorly reversible
clinical cascade’. These comments act as a potent reminder of the problem and
the potential for human factors to impede correct clinical diagnosis. In a more
recent study of emergency intubation outside the operating theatre Mort noted
that reliance
on indirect clinical tests for
diagnosing oesophageal intubation during emergency tracheal intubation led to
more hypoxaemia, severe hypoxaemia, regurgitation, aspiration, cardiac
dysrhythmia and cardiac arrest.17
Table 5 airway management and degree of harm. number of cases: n
|
Clinical area
|
airway management
|
|
|
good
|
good and poor
|
Poor
|
not classified
|
sum
|
|
All
|
30
|
79
|
65
|
10
|
184
|
|
All deaths
|
3
|
14
|
20
|
1
|
38
|
|
All death and
brain damage
|
3
|
16
|
27
|
2
|
48
|
|
|
|
|
|
|
|
|
ICU
|
4
|
19
|
13
|
|
36
|
|
ICU death
|
0
|
10
|
8
|
0
|
18
|
|
ICU death and
brain damage
|
0
|
11
|
11
|
0
|
22
|
|
|
|
|
|
|
|
|
Emergency
department
|
2
|
5
|
7
|
1
|
15
|
|
Emergency
department death
|
0
|
0
|
4
|
0
|
4
|
|
Emergency
department death and brain damage
|
0
|
1
|
4
|
0
|
5
|
46
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
■■■■■
CHAPTER 6
Results of second phase of
NAP4: ICU and the emergency department
An important recurrent finding was
misinterpretation of capnography when oesophageal intubation occurred during
cardiac arrest or cardiac arrest occurred as a consequence of it. This was also
noted in anaesthesia cases. Clinicians, mostly anaesthetists, repeatedly failed
to recognise that
a flat capnograph trace indicated
absence of ventilation and a misplaced tracheal tube. Nevertheless it has been
recognised for many years that during cardiopulmonary resuscitation capnography
is not flat but indicates a
low concentration of expired gas
(Figure 1).18 The 2010 International Consensus guidelines on Cardiopulmonary
Resuscitation specifically addressed the use of capnography to confirm advanced
airway placement during CPR.19
The report describes two studies
which included 21 oesophageal intubations amongst 297 patients in cardiac
arrest and in which waveform capnography was 100% sensitive and 100% specific
in identifying correct tracheal tube placement.20,21 In
contrast studies of colorimetric expired carbon dioxide detectors, non-waveform
expired capnometers, and oesophageal detector devices (both syringe aspiration
and self-inflating bulb types) had similar accuracy to clinical assessment for
confirming the tracheal tube position during cardiac arrest.22–30 The section concludes ‘waveform capnography is recommended to
confirm and continuously monitor the position of a tracheal tube in victims of
cardiac arrest ... it should be used in addition to clinical assessment ... if
not available, a non- waveform carbon dioxide detector or oesophageal detector
device in addition to clinical assessment is an alternative.’19
Capnography, or rather the failure
to use it, likely contributed to 17 outcomes of death or brain damage
on ICU
including four oesophageal intubations and 14 inadvertent tube displacements:
these account for 82% of events leading to death or brain damage in ICU.
In the emergency department
capnography use was higher, being definitely used 50% of intubation attempts
though this question was poorly completed. Despite
this, its use was certainly
not universal and failure to
use or misinterpretation of capnography led to
two
fatal unrecognised oesophageal intubations in the emergency department.
Correct use and interpretation of
capnography would have prevented
half of the deaths in the emergency department.
The contrast between rates of use of
capnography in anaesthesia and in ICU and the emergency department
is stark and
is reinforced by this project’s findings. Use of capnography in ICU has been
recommended by various authors and organisations.9,14,32–36 The breadth of these recommendations has ranged from that it
should be available for intubation to recommending its routine use ‘from
intubation to extubation’. Surveys repeatedly show its use fails even to meet
the narrowest recommendation. This project has shown that full implementation
would save lives.
In both areas needle
cricothyroidotomy had an unexpectedly high failure rare. There have been
numerous discussions as to whether needle or Seldinger or surgical approaches
to direct tracheal access are best and it might be argued that this project
provides evidence that needle cricothyroidotomy has a high failure rate and
therefore should be abandoned, particularly as surgical approaches were
generally successful (even when following failed needle cricothyroidotomy).
There are several reasons to be cautious about such a conclusion. The NAP4
project specifically studied events with poor outcomes and although we did seek
reports of all airway complications requiring emergency surgical airway it is
possible that a disproportionate number of successful rescue needle
cricothyroidotomies were not reported. Even if this explanation is not correct
it is not reasonable to abandon
the needle cricothyroidotomy
technique without a much more robust explanation of failures, which may have
been due to failures of training, use of inappropriate equipment, design
problems with appropriate equipment or technical failures during use. Examples
of each of these observed
in NAP4 include cephalad placement
of the device, use of
an intravenous cannula for cricothyroidotomy, mechanical
failures of a Ravussin cannula and successful passage of a fine bore needle followed
by unsuccessful (and inappropriate) attempts to ventilate with a low pressure
gas source.
Emergency surgical airway is the
‘final common pathway’ for all difficult airway algorithms. While much emphasis
is placed on the choice of device and technique there is relatively little
written about the decision-making process
Figure 1 Capnograph trace during cardiac arrest with
on-going cardiopulmonary resuscitation.
The positive trace is an indicator of
correct (i.e. tracheal) placement of the tracheal tube
■■■■■
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
47
CHAPTER 6
Results of second phase of
NAP4: ICU and the emergency department
and timing of emergency surgical
airway. Peterson, in an anaesthetic litigation setting, found that 42% of 179
difficult airway cases terminated in CICV.4 Errors of
technique were frequent causes of failure, particularly failure to ventilate
with a high pressure source when a narrow cricothyroid cannula was inserted.31 Of equal importance persistent attempts at intubation occurred
prior to rescue techniques and the authors noted ‘our data suggest the rescue
ability of (supraglottic airways) may have been reduced by the effects of
multiple preceding attempts at conventional intubation’ and that ‘in 2/3 of the
claims where CICV occurred a
surgical airway was obtained but was
too late to avoid poor outcomes.’ In NAP4 there were also cases, in anaesthesia
as well as in the ICU and emergency department, where persistent attempts at
intubation perhaps precipitated CICV, likely led to failure of rescue
techniques and definitely delayed emergency surgical airway.
what can be done to improve airway management in
the environments of iCu and the emergency department?
intensive Care unit
Capnography
▪
Capnography should be used for
intubation of all critically ill patients irrespective of location.
▪
Continuous capnography should be
used in all ICU patients with tracheal tubes (including tracheostomy) who are
intubated and ventilator dependent. Cost and technical difficulties may be
practical impediments to the rapid introduction of routine capnography. However
these problems need not prevent its implementation.
▪
Where capnography is not used the
clinical reason for not using it should be documented and reviewed regularly.
▪
Training of all clinical staff who
work in ICU should include interpretation of capnography. Teaching should
focus
on identification of airway obstruction or displacement. In addition
recognition of the abnormal (but not flat) capnograph trace during CPR should
be emphasised.
intubation
■ An intubation checklist should be developed and
used for all
intubations of critically ill patients. A checklist might usefully identify
preparation of patient, equipment, drugs and team. A checklist should include
identification of back-up plans.
Recognition of difficulty and back-up planning
■ Every ICU should have algorithms for management of intubation,
extubation and re-intubation. National efforts should be made to develop
evidence-based algorithms for ICU.
■ Patients at risk of airway events (i.e. those patients at
increased risk of problems or for whom the standard algorithms are not
appropriate) should be identified and clearly identifiable to those caring for
them.
■ A plan for such patients should be made and documented. The
planning should identify primary and back-up plans. The plan should also
identify any additional equipment and skills necessary to carry out the plan.
The plan should be communicated to on-coming staff at each staff handover,
including confirmation that the plans can still be carried out.
Tube displacement
■ Staff education should recognise and emphasise the risks of
airway displacement. Airway displacement may occur at any time but is more
frequent in obese patients, in patients with tracheostomy, during or after
patient movement and during sedation holds.
obesity
■ Obese patients on ICU should be recognised as at increased risk
of airway complications and at increased risk of harm from such events. Plans
to manage the airway should be particularly meticulous in this group.
■ Responsible bodies (e.g. Royal College of Anaesthetists,
Intensive Care Society) should work with other stake- holders and manufacturers
to explore two aspects of tracheostomies for obese patients. 1) Can design be
improved to reduce risk of displacement? 2) Can the optimal mode of fixation be
determined?
airway equipment
■ Every ICU should have immediate access to a difficult airway
trolley. This should have the same content and layout as the one used in that
hospital’s theatre department.
■ The airway trolley needs regular checking, maintenance and replacement
of equipment after use which should be appropriately documented.
■ A fibrescope should be immediately available for use on ICU.
Cricothyroidotomy
■ Training of staff who might be engaged in advanced airway
management of these potentially difficult patients should include regular,
manikin-based practice in the performance of cricothyroidotomies. Trainers
should regularly encourage their trainees to identify the correct landmarks
especially on obese patients.
48
naP4 Report and findings of the 4th National Audit Project of The
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■■■■■
CHAPTER 6
Results of second phase of
NAP4: ICU and the emergency department
■ Research is actively needed to identify the equipment and
techniques most likely to be successful for direct tracheal access in
critically ill patients. This research should specifically address whether the
same solutions are effective in obese patients.
Transfers
■ Recognising that transfers, whether inter- or intra- hospital,
are high-risk episodes, an airway assessment that includes patient, equipment,
back-up and staff skills should be made prior to transfers.
staffing
▪
Trainee medical staff who are
immediately responsible for management of patients on ICU need to be proficient
in simple emergency airway management. They need to have access to senior
medical staff with advanced airway skills at all hours.
▪
Where senior intensivists do not
have an anaesthetic background with advanced airway management skills, it is
recommended that specific protocols are in place to ensure experienced
anaesthetic cover can be called on to assist in management of difficult cases.
Trust management should support the financial implications.
education/training
▪
Junior medical staff who are to be
immediately responsible for management of patients on ICU need airway training.
This should include basic airway management, familiarisation with algorithms
for management of predictable airway complications and use/interpretation of
capnography. Training should identify the point at which trainees reach the
limit of their expertise and mechanisms for summoning more experienced
clinicians. Such training is likely to include simulation and team training.
▪
Regular audit should take place of
airway management problems or critical events in the ICU.
emergency department
Many of the above recommendations
apply equally to the emergency department. To these are added.
▪
Capnography should be used for all
intubations in the emergency department.
▪
Capnography should be used for all
anaesthetised patients in the emergency department.
▪
Capnography should be used for
intubated patients during transfers from the emergency department to other
departments.
▪
An intubation checklist should be
developed and used for all intubations of emergency department patients. A
checklist might usefully identify preparation of patient, equipment, drugs and
team. A checklist should include
■■■■■
■
■
■
■
■
■
■
■
■
identification of back-up plans.
Emergency departments should perform
a risk assessment to identify the type of patients and
their airway problems
that they can anticipate receiving. Equipment, training and strategies should
be planned around, though not restricted to, the anticipated patient groups.
Every emergency department should
have the airway equipment necessary to manage all the anticipated clinical
scenarios. This needs regular checking, maintenance and replacement of
equipment after use.
Every emergency department should
also have a difficult airway trolley. This should have the same content and
layout as the one used in that hospital’s theatre department and also needs
regular checking, maintenance and replacement of equipment after use.
In cases of airway compromise it is
generally preferable to secure the airway before moving the patient out of the
emergency department, but local considerations apply. Any decision to move a
patient with a threatened airway should be made by a senior clinician.
Robust processes should be
established to ensure the prompt availability of appropriately skilled and
senior staff at any time of the day or night to manage the airway within a
reasonable timeframe (the concept of the right practitioner, right place, right
time).
Joint training of emergency
physician and anaesthesia/ ICU staff is recommended. As above this training should
also identify the point at which trainees reach the limit of their expertise
and mechanisms for summoning more experienced clinicians. Such training is
likely to include simulation and team training.
Staff training should focus on the
anticipated
clinical presentations. Training should also include management of
failed intubation and emergency surgical airway techniques. Training should
include use of the airway equipment available in the emergency department.
Strong links and good communication
between senior clinicians in the emergency department, anaesthesia, ICU, ear
nose and throat surgery, and other relevant specialties are essential in
planning for, and managing, the emergency airway problems that present to the
emergency department. Consideration should be given to designating consultant
leads from each involved specialty to agree and oversee the management
of emergency airway problems
presenting to the emergency department.
Regular audit should take place of
airway management problems or events in the emergency department.
naP4 Report and findings of the 4th National Audit Project of The
Royal College of Anaesthetists
49
CHAPTER 6
Results of second phase of
NAP4: ICU and the emergency department
Research References
■ NAP4 has identified numerous areas of concern and potential
improvement in airway management in ICU and emergency departments. Airway
management on ICU and in the emergency department is as suitable an area for
future research as many other interventional areas. It is currently under explored.
Grant awarding bodies should recognise this. Several areas of potential
research are indicated above.
The main limitations of the NAP4
project are described in Chapter 5.11 For anaesthesia
events every UK NHS hospital had a LR: in contrast our network of LRs for ICU
and emergency departments likely covered only 50%
of hospitals. Although many cases in
these areas will
have been reported via anaesthesia LRs it is likely that a
higher proportion of events arising in ICU and emergency departments were not
notified. We cannot quantify these, but it is certainly possible that the
cohort of patients we studied represent only the ‘tip of the iceberg’ of such
cases in ICU and emergency departments.
Prior to surgery, airway management
is generally a necessary part of the process of anaesthesia to facilitate an
operation, while in both ICU and the emergency department the primary aim may
be securing the patient’s airway, with anaesthesia a necessity for that. Due to
preceding patho-physiological disturbance it may be difficult in these patients
to determine to what extent an adverse airway event was the cause of a poor
outcome and this was relevant to several cases in NAP4. At the reviewing stage
we aimed only to include those cases where the outcome was judged likely to be
related to
the airway event.
Conclusions
At least one-quarter of major
complications of airway management in hospitals are likely to occur in the
ICU
and emergency department. Case review has identified avoidable deaths and
areas of care that need improvement. We outline recommendations to make such
improvements.
At least one in four major airway
events in a hospital are likely to occur in ICU or the ED. The outcome of these
events is particularly adverse and these events are more likely to lead to
permanent harm or death than events in anaesthesia. Analysis of the cases has
identified repeated gaps in care that include: poor identification of at-risk
patients, poor or incomplete planning, inadequate provision of skilled staff
and equipment to manage these events successfully, delayed recognition of
events and failed rescue due to lack of or failure of interpretation of
capnography. The project findings suggest avoidable deaths due to airway
complications occur in ICU and the emergency department.
1 Schwartz DE, Matthay MA, Cohen NH. Death and other
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4 Peterson GN et al. Management of the Difficult Airway:
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32 Cheifetz IM, Myers TR. Respiratory therapies in
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34 Goldhill D, Cook TM, Waldmann C. Airway incidents in
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35 Safety Statement Capnography outside the Operating
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36 Standards for the care of adult patients with a
temporary tracheostomy. ICS, 2008 (www.ics.ac.uk/intensive_care_
professional/standards_and_guidelines/care_of_the_adult_
patient_with_a_temporary_tracheostomy_2008, accessed 2 January 2011).
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52
