ANZCA Bulletin June 2011 - Australian and New Zealand College of ...

Airway Management
As the third report on airway
disasters appears in this edition of
the Bulletin it is timely to review the
groundbreaking project of the 4th
National Audit Project (NAP4) of the
Royal College of Anaesthetists (RCoA).
This collaborative study, involving the
RCoA and the Difficult Airway Society
(DAS), was a one-year prospective
audit of serious airway complications
in anaesthesia, intensive care and
emergency departments for all 309
National Health Service Hospitals in
the UK, with an expert panel being
appointed to assess every report.
The full report is available on the
RCoA website 1 and the British Journal
of Anaesthesia has both an excellent
editorial 2 and two articles reporting
on complications related to general
anaesthesia 3 as well as to intensive care
and emergency departments. 4
Major complications related to
general anaesthesia were identified in
a total of 133 cases which the authors
assess as 1/22000 cases, assuming an
estimated denominator of 2.9 million
general anaesthetics administered
annually. During this one year period
there were 13 deaths and three cases
of irreparable brain damage. Even
with this carefully planned survey
the authors concede that there may
be under-reporting and that as few
as 25 per cent were reported. This
would certainly be the experience of
the Victorian Consultative Council on
Anaesthetic Mortality and Morbidity
(VCCAMM). The indicators for inclusion
in the study were death, brain damage,
the need for an emergency surgical
airway, unplanned admission to ICU
or prolongation of stay in ICU. Obesity
was considered an important risk factor
and was defined as a body mass index
of >30 kg m -2 which was identified in
42 per cent of reports. Also of note was
that over half of the patients were ASA
P1-2 and under the age of 60 and most
events occurred during elective surgery
while under the care of consultant
anaesthetists.
The most common primary airway
problems in anaesthesia were failed
intubation, aspiration of gastric
contents and, importantly, problems
related to tracheal extubation or
removal of a supraglottic airway.
Aspiration of gastric contents was the
single most common cause of death and
occurred in 14 cases with a supraglottic
airway and eight cases with a tracheal
tube, indicating that risks of aspiration
have not always been adequately
assessed when a supraglottic airway
is employed.
In 58 cases an emergency surgical
airway was attempted. Twenty-nine
of these cases underwent surgical
tracheostomy as a primary event while
cricothyrotomy was attempted in 29, of
which 15 failed and required surgical
rescue: cricothyroidotomy performed by
anaesthetists had a high rate of failure.
The second section of the NAP4
report relates to airway incidents
in emergency or intensive care
departments. Inclusion criteria were
the same as for the anaesthesia related
events but also included events
occurring during transport between
departments. Thirty-six reports
concerned patients in ICU and 15 in the
emergency department. Of these there
were 18 deaths and four cases of brain
damage in ICU patients and four in the
emergency department.
Of the ICU patients 61 per cent were
aged less than 60 and 22 per cent were
ASA P1-2. Invasive ventilation had
been established in 19 patients and non
invasive in eight and there was a BMI of
>30kg m -2 in 47 per cent. Of note was the
occurrence of 46 per cent of incidents
out of hours with many managed by
junior doctors without training in
airway management. This problem was
less common in emergency departments
where anaesthetists were more often
available and where emergency
consultants were on duty 24 hours a day.
In ICU the main primary airway events
were tracheostomy related problems,
tracheal tube misplacement and
failed intubation and there were three
unrecognised oesophageal intubations,
two of which were fatal. Poor planning
and training were identified in many of
these cases as well as the unavailability
of equipment, notably capnography.
In recent years the majority of airway
incidents reported to VCCAMM have
occurred in areas outside the operating
theatre and VCCAMM has repeatedly
recommended that whenever the patient
is intubated and there is artificial
ventilation, capnography is essential.
NAP4 has claimed that it is likely that
over 79 per cent of airway deaths in
ICU could have been prevented had
continuous capnography been used.
Even now it is not known how many
intensive care units in Australia still do
not have the capability of continuous
capnography in all ventilated patients.
However it must be recognised that
equipment alone is not sufficient and
that there must also be training in the
interpretation of absent or altered CO2
waveforms and that the possibility of
equipment error is small and must not
distract from the need for urgent action.
NAP4 is a seminal project with
enormous implications for improvement
in airway management, particularly
outside the operating theatres, and
the articles in the British Journal of
Anaesthesia are highly recommended
reading as well as the web site of the
RCoA. 1
Dr Patricia Mackay
Communication/Liaison Portfolio
References
1. RCoA Website. www.rcoa.ac.uk/index.
aspPageID-1089
2. Norris AM, Hardman JG, Asai T Editorial:
A firm foundation for progress in airway
management. Br J A naesth 2111;
106: 513-516
3. Cook TM, Woodall N, Freck C. Major
Complications of Airway Management in
the UK. Part 1 Anaesthesia. Br J Anaesth
2111; 106: 617-31
4. Cook TM, Woodall N, Harper J, Benger
J. Major Complications of Airway
Management in the UK. Part 2: intensive
care and emergency departments.
Br J Anaesth 2011; 106: 632-42
ANZCA Bulletin June 2011 63