Intubacion dificil

Audit
Anaesthesia
andIntensive Care
Difficult and failed intubation in the first
4000 incidents reported on webAIRS
Yasmin Endlich1,2
, Julie Lee3,4
and Martin D Culwick3
Abstract
A review of the first 4000 reports to the webAIRS anaesthesia incident reporting database was performed to analyse
cases reported as difficult or failed intubation. Patient, task, caregiver and system factors were evaluated. Among the
4000 reports, there were 170 incidents of difficult or failed intubation. Difficult or failed intubation incidents were most
common in the 40–59 years age group. More than half of cases were not predicted. A total of 40% involved patients with
a body mass index >30 kg/m2
and 41% involved emergency cases. A third of the reports described multiple intubation
attempts. Of the reports, 18% mentioned equipment problems including endotracheal tube cuff rupture, laryngoscope
light failure, dysfunctional capnography and delays with availability of additional equipment to assist with intubation.
Immediate outcomes included 40 cases of oxygen desaturation below 85%; of these cases, four required cardiopulmo-
nary resuscitation. The majority of the incidents resulted in no harm or minor harm (45%). However, 12% suffered
moderate harm, 3.5% severe harm and there were three deaths (although only one related to the airway incident).
Despite advances and significant developments in airway management strategies, difficult and failed intubation still
occurs. Although not all incidents are predictable, nor are all preventable, the information provided by this analysis
might assist with future planning, preparation and management of difficult intubation.
Keywords
Airway management, difficult intubation, failed intubation, incident reporting, quality and safety
Introduction
Management of the difficult airway, whether expected
or unexpected, is a core skill for all anaesthetists.
Currently there is no single test of sufficiently high sen-
sitivity and specificity to predict a difficult airway reli-
ably and ‘standard bedside tests’ are poorly predictive
for a difficult intubation.1,2
Difficult intubation has
been reported to occur in about 1%–6.2% of all gen-
eral anaesthetics3–7
and the incidence of failed intuba-
tion is as high as 1 in 1000–2000 general anaesthetics.1
Preoperative assessment is an integral part of anaes-
thetic management, which includes an assessment of
patient factors, task factors, system factors and care-
giver factors. Anaesthetists have a range of fundamen-
tals for advanced airway management equipment at
their disposal. Various airway societies worldwide
have published algorithms for the management of
unexpected difficult intubations, including guidelines
for the structured use of airway devices.8–11
Cognitive
aids complement and facilitate the use of these existing
airway algorithms in real time.12
Therefore, anaesthesia
has become increasingly safe and significant complica-
tions of airway management are rare. However, they
have the potential to be life-threatening and may cause
significant harm, including death.2,13,14
WebAIRS is an internet-based voluntary de-
identified anaesthetic incident recording system used
by anaesthetists in Australia and New Zealand. It is
owned and funded by three organisations: the
Australian and New Zealand College of Anaesthetists
(ANZCA), the Australian Society of Anaesthetists and
1
Department of Anaesthesia, Royal Adelaide Hospital, Women’s and
Children’s Hospital, Adelaide, Australia
2
The University of Adelaide, Adelaide, Australia
3
Department of Anaesthesia, Royal Brisbane and Women’s Hospital,
Brisbane, Australia
4
The University of Queensland, Brisbane, Australia
Corresponding author:
Yasmin Endlich, Royal Adelaide Hospital, Port Road, Adelaide, South
Australia 5000, Australia.
Email: yasmin.endlich@gmail.com
Anaesthesia and Intensive Care
0(0) 1–11
! The Author(s) 2020
Article reuse guidelines:
sagepub.com/journals-permissions
DOI: 10.1177/0310057X20957657
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the New Zealand Society of Anaesthetists. Registered
anaesthetists across Australia and New Zealand have
been able to report anaesthetic incidents via the web-
page www.anztadc.net since 2009. Data describing the
incidents can be entered both via non-mandatory tick
boxes and in the form of text, allowing reporters to
describe the incident in their own words and providing
opportunity for reflections about contributing and mit-
igating factors.
An overview of the first 4000 incidents was published
in 2017. The aim of this paper is to report on the analysis
of all incidents coded as ‘Difficult Intubation’ or ‘Failed
Intubation’ in the first 4000 reports.
Methods
This study assessed all incidents coded as ‘Difficult
Intubation’ or as ‘Failed Intubation’ in the first 4000
reports logged on the webAIRS system. Data were col-
lected in compliance with the National Health and
Medical Research Council recommendations for qual-
ity assurance data. The methods of de-identified data
collection have been reported previously.15
Multicentre
ethics approval is maintained at the Royal Brisbane
and Women’s Hospital Human Research Ethics
Committee (HREC/11/QRBW/311) and the Nepean
Blue Mountains Local Health District (HREC/12/
NEPEAN/18). In New Zealand, ethics approval has
been obtained from the Health and Disability Ethics
Committee (MEC/09/17/EXP).
Denominator data are not collected by webAIRS
and the numerator data are submitted voluntarily,
which precludes absolute risk calculations. However,
as described in a previous article,16
it is possible to
use the denominator data from other patient-related
incidents (in this case, not difficult or failed intubation
incidents) in the webAIRS database as a surrogate
denominator, acknowledging that this may not repre-
sent population-based denominator data. In effect,
demographic data of patients involved in the difficult
or failed airway incidents were related to the demo-
graphics of patients in the database who were involved
in other incidents. In each case, the incidents were
drawn from the first 4000 incidents reported. Risk
ratios (RR) were then calculated.
The data coded by the reporters as ‘Difficult
Intubation’ or as ‘Failed Intubation’ were extracted
from the first 4000 reports in the webAIRS database.
The reports were assessed and analysed by all authors
and reports were excluded based on duplication of
data, irrelevance, or insufficient detail for analysis.
Two of the 172 reports were identified as duplicates:
in both cases they were submitted within a short time
frame of each other, had the same age group and
gender and had similar descriptions of the incident.
The remaining reports were analysed, assessed and
categorised by all authors.
The authors defined an incident as failed intubation
if any one of the following three conditions occurred
during the attempted intubation.
1. The patient had to be woken up, or when the final
airway device was either a facemask, a supraglottic
airway device (SAD), or a subglottic front-of-neck
rescue.
2. Any incident initially involving direct or indirect
laryngoscopy techniques but subsequently requiring
rescue intubation using a fundamentally different
technique such as an intubating laryngeal mask
airway (ILMA, FastrachTM
, Intavent Ltd,
Reading, UK), a fibreoptic intubation (FOI)
device, or front-of-neck access (FONA).
3. Unsuccessful elective FOI.
All reports were analysed using paradigm grouping
of ‘potential risk factors’, ‘management’ and ‘out-
comes’. Analysis of potential risk factors was further
divided into ‘patient factors’, ‘task factors’, ‘caregiver
factors’ and ‘system factors’. Analysis of management
was divided into ‘immediate management’, ‘airway tech-
nique’ and ‘targeted other’, which included the mention-
ing of cognitive aids, the use of muscle relaxants and
optimisation of positioning and facemask ventilation.
These were then examined and assessed by all
authors.
Results
Of the 4000 reports, 71 were omitted from this study as
they did not involve an individual patient. Of the
remaining 3929 webAIRS incidents, 170 reported diffi-
culties encountered during endotracheal intubation. Of
these cases, 108 (63.5%) were analysed as ‘difficult intu-
bation’ and 62 (36.4%) as ‘failed intubation’. The demo-
graphic data from these 170 patients were compared to
the demographic data of the remaining patients (3759)
to calculate the RR related to specific risk categories.
There was almost even gender distribution (Table 1).
As this was also the case with the remainder of the reports
in the webAIRS database, the RR for either males or
females having a difficult or failed airway event
approached one. The American Society of
Anesthesiologists physical status (ASA PS) had little
effect on the RR of having a difficult or failed airway
event (Table 2). The RR for ASA PS 1 was 0.73 and
for ASA PS 2 1.33, with ASA PS 3 and ASA PS 4 both
within this range. Most patients were ASA PS 2 or 3. The
patient age category 40–59 years was associated with an
increased RR of a difficult or failed airway event (1.65,
Table 3). Age <17 years and >79 years had a reduced
2 Anaesthesia and Intensive Care 0(0)

RR, but the number of incidents with patients in these
age categories was very low. The highest proportion
(38%) was for the 40–59 years category followed by
60–79 years (28%) and 17–39 years (20%).
Of the events categorised as difficult or failed intuba-
tion cases, 40% occurred in patients with a body mass
index (BMI) >30 kg/m2
(Table 4). A total of 14% of the
reports did not specify a BMI. The RR of a difficult or
failed intubation event for incidents in which patients
had a BMI >30 kg/m2
was 1.66 and for patients with a
BMI 25–30 kg/m2
was 1.20, suggesting that higher BMI
was associated with a higher proportion of difficult and
failed intubation compared with patients having other
incidents. The Australian Institute for Health and
Welfare (AIHW) national BMI data for adults17
indi-
cate that the proportion of Australians with a BMI >30
kg/m2
for the years 2007–2008, 2011–2012 and 2014–
2015 was 24.4%, 27.2% and 27.5% respectively. The
webAIRS data were collected over this period (2009 to
mid-2016). The average proportion of BMI >30 kg/m2
in the AIHW data was 26.4%, which is numerically
close to the proportion of patients with a BMI >30kg/
m2
having non-airway events in the first 4000 incidents
in the webAIRS database (24%).
Of the difficult or failed intubation events, 41%
occurred in patients undergoing emergency procedures
compared with 33.5% of patients in the remainder of
the database undergoing emergency procedures (RR
1.23) (Table 5).
A total of 80% of the incidents occurred while under
the care of an anaesthetic specialist; 86% of patients
were undergoing general anaesthesia for their planned
procedure.
Of all incidents, 92% occurred in the operating the-
atre and 5% in remote areas (in 3% the site was not
specified). A rapid sequence induction (RSI) was per-
formed in 30% of incidents, mostly in emergency cases.
In a minority of cases, RSI was not mentioned in asso-
ciation with an emergency case. Significant time pres-
sure to secure the airway was described in 21% of
incidents.
In 66% of incidents, at least one predictive risk
factor (based on clinical examination or history) was
reported as positive for patients with difficult or failed
intubation. In 10% of difficult or failed intubation inci-
dents, no predictors were included in the report, and in
24% no airway assessment was mentioned. In 38% of
difficult or failed intubation incidents at least one ana-
tomical risk factor was recorded and in 18% patients
had a previous history of a difficult airway (Table 6).
In 56% of difficult or failed intubation incidents, the
difficult airway was not anticipated.
Table 1. Sex of patients involved in the reports.
No difficulty with intubation (n ¼ 3759) Difficult or failed intubation (n ¼ 170)
Sex n Proportion 95% CI n Proportion 95% CI RR
F 1741 0.46 (0.45–0.48) 71 0.418 (0.40–0.43) 0.90
M 1706 0.45 (0.44–0.47) 82 0.482 (0.47–0.50) 1.06
Not Specified 312 0.08 (0.07–0.09) 17 0.1 (0.09–0.11) 1.21
Total 3759 170
CI: confidence interval; RR: relative risk (the proportion of difficult or failed intubation incidents versus no difficulty with intubation incidents); F:
female; M: male.
Table 2. American Society of Anesthesiologists physical status classification of the patients involved in the reports.
ASA PS n Proportion 95% CI n Proportion 95% CI RR
1 761 0.20 (0.19–0.22) 25 0.147 (0.16–0.16) 0.73
2 1216 0.32 (0.31–0.34) 73 0.429 (0.41–0.45) 1.33
3 1184 0.32 (0.30–0.33) 53 0.312 (0.30–0.33) 0.99
4 363 0.10 (0.09–0.11) 14 0.082 (0.07–0.09) 0.85
5 37 0.01 (0.007–0.013) 1 0.006 (0.003–0.008) 0.60
Not Specified 198 0.05 (0.05–0.06) 4 0.024 (0.02–0.03) 0.45
Total 3759 170
ASA PS: American Society of Anesthesiologists physical status; CI: confidence interval; RR: relative risk (the proportion of difficult or failed intubation
incidents versus no difficulty with intubation incidents in each ASA PS).
Endlich et al. 3

In 14 incidents (8.2%), the anaesthetist had worked
for 10–16 hours at the time of the incident. In two
incidents the anaesthetist had worked more than 16
hours (Table 7). Fatigue was mentioned in 14% of
the reports. A total of 32 incidents (19%) occurred
after hours and there was a high RR (1.8) in the time
block 22.00 to 07.59 hours (Table 8).
Human factors were described in a small proportion
of events. A total of 36 reports (21%) described signif-
icant pressure to proceed. Of incidents, 31 (18%)
reported equipment problems affecting either basic or
advanced airway management devices. Requested
equipment was unavailable in 13% of incidents.
Team and communication issues were reported in
18% of incidents.
The initial successful oxygenation method (when the
planned airway strategy failed) was facemask ventila-
tion in 71 incidents (41.8%). In 22 (12.9%) it was ven-
tilation via an SAD, in five (3%) it was endotracheal
intubation, and subglottic airway access was obtained
in two incidents (1.2%). An SAD other than an ILMA
was described as part of airway management in 35.3%
Table 3. Age of the patients involved in the reports.
Age (years) n Proportion 95% CI n Proportion 95% CI RR
Under 5 299 0.08 (0.07–0.09) 7 0.04 (0.04–0.05) 0.52
5–16 230 0.06 (0.05–0.07) 5 0.03 (0.02–0.04) 0.48
17–39 770 0.21 (0.19–0.22) 34 0.20 (0.19–0.21) 0.98
40–59 870 0.23 (0.22–0.25) 65 0.38 (0.37–0.40) 1.66
60–79 1119 0.30 (0.28–0.31) 48 0.28 (0.27–0.30) 0.95
80þ 331 0.09 (0.08–0.10) 6 0.035 (0.03–0.04) 0.40
Not specified 140 0.04 (0.03–0.04) 5 0.029 (0.02–0.035) 0.80
Total 3759 170
CI: confidence interval; RR: relative risk (the proportion of difficult or failed intubation incidents versus no difficulty with intubation incidents for each
age range).
Table 4. Body mass index of patients with and without intubation difficulty.
BMI n Proportion 95% CI n Proportion 95% CI RR
<18.5 91 0.02 (0.02–0.03) 3 0.02 (0.01–0.02) 0.73
18.5–25 1238 0.33 (0.31–0.34) 41 0.24 (0.23–0.26) 0.73
25–30 626 0.17 (0.16–0.18) 34 0.20 (0.19–0.21) 1.20
Above 30 904 0.2 (0.23–0.25) 68 0.40 (0.38–0.42) 1.66
Not specified 900 0.24 (0.23–0.25) 24 0.14 (0.13–0.15) 0.60
Total 3759 170
BMI: body mass index, kg/m2
; CI: confidence interval; RR: relative risk (proportion of difficult or failed intubation incidents versus no difficulty with
intubation incidents for each BMI range).
Table 5. Urgency of the procedure involved.
Urgency n Proportion 95% CI n Proportion 95% CI RR
Elective 2381 0.63 (0.62–0.65) 99 0.58 (0.57–0.60) 0.92
Emergency 1258 0.34 (0.32–0.35) 70 0.41 (0.40–0.43) 1.23
Not Specified 120 0.03 (0.03–0.04) 1 0.01 (0.00–0.01) 0.18
Total 3759 170
CI: confidence interval; RR: relative risk (proportion of difficult or failed intubation incidents versus no difficulty with intubation incidents).

of reports and was successful in restoring ventilation in
20.6% of incidents. In 12% of reports, attempts at ven-
tilation using an SAD failed. The ILMA was used in 15
of the reports (8.8%) and provided successful ventila-
tion in ten. Blind intubation through an SAD or ILMA
was successful in one incident and failed in two.
Bronchoscopy-guided intubation via an SAD or
ILMA was successful in ten incidents and failed in five.
The final airway device used was an endotracheal
tube in 137 incidents, facemask in 11, SAD in 16, and
subglottic access in five events. The airway of one
patient could not be rescued by any technique and
the patient died.
The anaesthetist elected to wake up the patient in 20
incidents, of which three proceeded to an awake
fibreoptic intubation and another two were intubated
by a different operator. In ten incidents the anaesthetist
was able to proceed without an endotracheal tube and
in five incidents emergency FONA was required.
More than three intubation attempts were described
in 43 incidents (25%) and more than four in 13 (7.6%).
In seven reports there were more than five attempts
specified. A muscle relaxant was used electively in 136
of the incidents and as part of airway rescue manage-
ment in five. In 99 incidents (58%) the anaesthetist used
at least one type of videolaryngoscope (VL) of which
31 (18.2%) were unsuccessful. A total of 47 reports
(27.6%) described the use of a fibreoptic technique,
12 electively (7%) and the remaining 35 (20.6%)
unplanned as part of the airway crisis management.
In 40 incidents (23.5%) the oxygen desaturations
were reported to fall below 85% during the airway
manoeuvres, of which four were associated with cardi-
ac arrest. Patients were reported to suffer from minor
harm in 45% of incidents, moderate harm in 12% and
severe harm in 3.5%. In 7.6% of reports, whether harm
occurred was not specified. There were three deaths. Six
Table 7. Hours on duty of anaesthetist when incident occurred.
Hours on duty n Proportion 95% CI n Proportion 95% CI RR
0 to <10 hrs 2962 0.79 (0.78–0.8081) 144 0.85 (0.836–0.859) 1.08
10 to <16 hrs 211 0.06 (0.05–0.063) 12 0.07 (0.062–0.079) 1.26
16 to <24 hrs 19 0.06 (0.00–0.01) 2 0.01 (0.008–0.015) 2.33
More than 24 hrs 6 0.002 (0.000–0.003) 0 0
Not specified 561 0.15 (0.138–0.161) 12 0.07 (0.062–0.079) 0.47
Total 3759 170
CI: confidence interval; RR: relative risk (the proportion of difficult or failed intubation incidents versus no difficulty with intubation incidents for each
hours on duty range).
Table 8. Time of day of incident.
Time of day n Proportion 95% CI n Proportion 95% CI RR
0800–1800 2953 0.79 (0.77–0.80) 137 0.81 (0.79–0.82) 1.026
1800–2200 317 0.08 (0.08–0.09) 17 0.10 (0.09–0.11) 1.186
2200–0759 184 0.05 (0.04–0.06) 15 0.09 (0.08–0.10) 1.803
Not specified 305 0.08 (0.07–0.09) 1 0.006 (0.003–0.008) 0.072
Total 3759 170
CI: confidence interval; RR: relative risk (proportion of difficult or failed intubation incidents versus no difficulty with intubation incidents for each time
of day (hours) range).
Table 6. Predictive risk factors for difficult or failed intubation
incidents.
Factor Yes No
Interincisor gap <3 cm 13 15
Class B or C – mandibular protrusion 9 9
Mallampati score >2 25 32
Retrognathia 14 0
Beard 10 1
Reduced neck extension/range of movement 35 14
Thyromental distance 6 cm 18 21
Sternomental distance 12.5 cm 1
Wilson score 2 0 0
Pregnancy 9
Neonate 3
Previous difficult intubation 30 22
Endlich et al. 5

patients (3.5%) suffered from a permanent injury as
assessed by the authors (based on the information pro-
vided in reports). The reporters considered 39% of the
incidents preventable.
Discussion
Of the first 4000 incidents reported to webAIRS, 4.25%
were coded as difficult or failed intubation. This is sim-
ilar to the percentage of ‘difficulty with intubation’
incidents published in the AIMS report in 1993.18
However, neither AIMS nor webAIRS data indicate
the risk of an incident occurring. Both systems rely
on voluntary reporting so the numerator for any risk
calculation cannot be ascertained. Similarly, the
denominator is not known. This is because the inci-
dents are de-identified and data on the number of epi-
sodes of anaesthesia care performed by individual
anaesthetists reporting across sites is not known.
Nevertheless, the webAIRS data suggest the number
of incidents categorised as difficult or failed intubation
still require attention. As expected, the majority of
reported incidents occurred while under the care of a
specialist anaesthetist and most occurred when patients
were undergoing general anaesthesia. However, inci-
dents often remain unpredictable and many are not
preventable. Outcomes range from near misses and
minor harm, to severe harm in a minority of cases
and even death.
Difficult versus failed intubation
Various airway societies worldwide have published
slightly different definitions of what constitutes a
‘Difficult intubation’ and what is defined as a ‘Failed
intubation’.6,8–11
Assessment of the narratives showed
there was inconsistency in the definition by reporters as
well. Therefore, the authors decided to create a defini-
tion that was not ambiguous for the purpose of this
analysis. The definition was designed to detect a failure
of any method that constituted the initial intubation
plan and required rescue by a different technique or
operator. The incident was counted as a failed intuba-
tion if the final airway device was not an endotracheal
tube or if the patient had to be woken as part of unsuc-
cessful intubation attempts, irrespective of the initial
method chosen. Equally, any incident where direct or
indirect laryngoscopy guided intubation attempts were
unsuccessful and subsequently required asleep airway
rescue using a different technique such as an ILMA,
FOI or FONA. Conversely, there were also cases of
elective FOI methods that failed and were rescued by
different methods of oral intubation.
Demographic predictors: Gender ASA PS and age
There was no apparent gender bias (Table 1). The ASA
PS had little influence, although there were very few
incidents in the ASA 4 and 5 categories (total 15) to
adequately assess these potential predictors. Most of
the difficult and failed airway intubation incidents
occurred in patients between 40 and 59 years of age
(38.2%). The RR of a difficult or failed intubation inci-
dent occurring in this age range versus non-airway inci-
dents occurring in this age range was 1.65, possibly
indicating this age group might be at higher risk of
airway events. There were too few patients in the
below 5 years and 80 years age range (seven and six
respectively) to adequately assess the influence of these
potential predictors. Airway management in paediatric
patients is usually considered straightforward unless
there are congenital abnormalities or acute injuries or
infections affecting the airway. In this cohort, all but
one of the paediatric patients was either suffering from
a congenital syndrome, had undergone surgeries on the
head or neck, or presented with acute airway bleeding
or swelling. Three of the patients were neonates requir-
ing urgent resuscitation and intubation.
Airway assessment and prediction of difficult
intubation
More than half of the difficult intubations identified in
this study were not predicted. As reporters did not need
to provide details of airway assessment, it is not
possible to comment on the relationship between pre-
operative airway assessment and the likelihood of
incidents. However, 30 patients had documentation
describing previous difficult airway management.
Findings from the Danish Anaesthesia Database have
shown that previous difficult tracheal intubation is
associated with a six-fold increase in the likelihood of
being difficult again and a previous failed intubation is
associated with a 22-fold increase in the likelihood of
failed intubation in future procedures.19
Body Mass Index
Patients with a high BMI were highly represented in the
reports. About 40% of the incidents were reported in
patients with a BMI 30 kg/m2
. The RR of a difficult
or failed intubation incident occurring in patients with
a BMI 30 kg/m2
versus non-airway events occurring
in patients with a BMI 30 kg/m2
was 1.66. The pro-
portion of BMI 30 kg/m2
in the AIHW17
national
health surveys during the same period of the
webAIRS incidents reports was an average of 26.4%,
which is close to the 24% across the 4000 webAIRS
reports.

A previous review of 50,000 anaesthetics described a
BMI 25 kg/m2
as an independent risk factor for dif-
ficult facemask ventilation.20
Results were similar in
this report. Of the 170 patients (60%), 102 had a
BMI 25 kg/m2
. Airway management was difficult in
64 and intubation failed in 38 of these 102 patients. A
third of these patients then suffered from adverse
sequelae resulting from airway management, ranging
in severity from minor airway trauma to aspiration,
to intensive care unit (ICU) admission and FONA
access. Although obesity alone may not be considered
a standalone predictor of difficult tracheal intuba-
tion,21
this series shows it is still prevalent across diffi-
cult and failed airway incidents.
Emergency and urgent cases
A proportion of the procedures were performed under
stressful conditions, with 36 reports describing signifi-
cant pressure to proceed. Most of these pressured cir-
cumstances, difficulties in teamwork and poor
communications were reported. It was a recurrent
issue that findings of a previous airway assessment
were not communicated or missed by the treating
anaesthetist.
A high percentage (41%) of the incidents coded as
difficult and failed intubation were classified as emer-
gency cases. This is consistent with other studies; pre-
vious literature has shown that rates of airway
complications, including difficult intubation and the
risk of aspiration, are increased in emergency
cases.2,13,14,16
The RR of a difficult or failed airway
incident occurring during an emergency procedure
versus a non-airway incident occurring during an emer-
gency procedure was 1.23. However, it is likely that
emergency procedures are more highly represented
than elective procedures across the webAIRS database.
Fatigue is known to affect performance reducing
vigilance and the accuracy of response, thereby con-
tributing to adverse events.22–26
Fatigue was reported
in 14% of incidents as a contributing factor. Although
most of the incidents occurred during daylight hours,
about 19% occurred after-hours (1800–0759 hours),
compared with 13.3% of non-airway incidents occur-
ring in this time of day range (RR 1.41). A total of 10%
of the incidents occurred when anaesthetists had been
working 10–16 hours. The RR of a difficult or failed
intubation incident occurring in this duration of work
range compared to non-airway incidents occurring in
this duration of work range was 1.4. Although it is not
possible to calculate the absolute risk in this study, one
can assume the majority of procedures are performed
during normal business hours (0800–1759).
Intubation attempts
Analysis of the narratives have shown that a third of
the reports described multiple intubation attempts and
some of these required a significant amount of time
until intubation was finally successful. The incidents
in this study were reported in a time frame from 2009
to 2016. In 2011, the Fourth National Audit Project
(NAP4) was published in the United Kingdom14
and
the results were released, which resulted in the devel-
opment of the new Difficult Airway Society’s difficult
intubation guidelines in 2014.8
The use of a cognitive
aid in airway management, the Vortex, was introduced
in 201612
and has gained significant popularity. These
guidelines and cognitive aids aim to take human factors
into account, including techniques and guidance to
avoid fixation error and encourage no more than
three intubation attempts. Nevertheless, our data
show that from 2009 to 2016, there had been a large
number of incidents where anaesthetists repeated intu-
bation attempts several times. In only a minority of the
patients, successful oxygenation via facemask or SAD
was used as an opportunity to wake up the patient.
The largest number of intubation attempts described
in this cohort was eight attempts or more in two sepa-
rate incidents. One event was an after-hours intubation
as part of the preparation for transporting an unwell
neonate. Direct intubation was attempted by different
operators until successful. The other patient suffered
from a significant congenital underlying mid-facial
abnormality and was scheduled to undergo elective sur-
gery. The procedure was abandoned after multiple
failed intubation attempts and the patient was woken
up breathing spontaneously through an SAD.
Equipment issues
A total of 31 incidents (18%) reported equipment prob-
lems. Six reports mentioned endotracheal tube cuff fail-
ure requiring reintubation. The laryngoscope light was
not functioning or insufficient in four incidents, causing
a delay in securing a definitive airway. Monitoring
issues, including dysfunctional capnography, were
mentioned in five incidents, resulting in additional intu-
bation attempts. Several incidents reported advanced
airway equipment, including VLs, failing during
rescue intubations, with five incidents reporting light
or system failures, whereas the setup time for emergent
bronchoscopes was ‘taking too long’ or ‘too difficult’ in
two of the incidents. Urgently required equipment was
unavailable in 13% of incidents. Specifically, fibreoptic
bronchoscopes were missing from the difficult intuba-
tion trolley in four incidents. The lack of equipment
was usually noticed late during the procedure
when airway manoeuvres had already commenced.
Endlich et al. 7

These incidents emphasise the importance of thorough
preoperative checking and planning of the availability
of potentially needed airway equipment.
Airway rescue devices
The most successful rescue device across the incidents
reported, after other techniques at oxygenation had
failed, was facemask ventilation (71, 41.8%). Once suc-
cessful ventilation was obtained, only 20 anaesthetists
elected to wake their patient as part of their failed ini-
tial airway management. Two of these incidents
described patients undergoing emergency after hours
procedures when initial intubation attempts by an
anaesthetic trainee failed. One of these patients was a
known difficult airway, but previous records were
reported as not available. Both times the senior anaes-
thetist who was called back for rescue decided against
an awake FOI (AFOI) and re-induced anaesthesia in
the patient and attempted a similar intubation tech-
nique as that used initially. This resulted in significant
difficulties in securing the airway, including multiple
attempts with different airway devices until intubation
was finally successful. As a result, one patient required
ICU admission until airway swelling subsided.
It is of note that both patients were at high risk of
aspiration due to their underlying pathology and both
had predictors of potentially being a difficult
intubation.
SADs have been advocated as a rescue device for
failed intubation in national and international difficult
airway guidelines and cognitive aids.8–12
The literature
on their success and failure rates is sparse, but first-time
insertion success rates have been described as being as
high as 90%–100%, depending on the device used.27–29
In the 170 difficult and failed incidents reported, an
SAD had been part of airway management in 60 inci-
dents (35.3%) of which 35 (20.6%) were successful in
restoring ventilation. However, in 21 incidents (12.4%),
rescue using an SAD failed. In a significant proportion
of these failures, attempts at providing oxygenation via
facemask ventilation also proved difficult or unsuccess-
ful. Ventilation via the ILMA was attempted in 15
incidents (8.8%) and ventilation was successful in ten
of these incidents (5.9%). A successful blind intubation
technique through the ILMA was described in only one
incident. There were two reports of failed blind intuba-
tion attempts, including one using an ILMA. In both of
these incidents the reporters had multiple failed
attempts at rescuing the patient’s airway using a
range of different equipment and techniques. One of
these two patients was woken up after significant desa-
turation and the other patient required a rescue
FONA. In contrast, bronchoscopy-guided intubations
using an SAD during difficult airway management
were successful in ten incidents, using a range of differ-
ent SADs and the support of intubating catheters in
some. One reporter mentioned difficulties in lifting
the elevator bar of the ILMA with the flexible bron-
choscope, which was solved by advancing the endotra-
cheal tube first.
The use of the blind intubation technique might
compromise an already tenuous airway, and the wide-
spread availability of fibreoptic scopes might make this
technique redundant in the future.
The analysis of the data exemplifies that attempts at
securing the airway using a range of different techniques
and devices yielded varying success rates. This supports
observations from large studies examining airway man-
agement, describing that when one airway technique is
difficult or fails, the risk of other techniques being diffi-
cult or failing is considerably increased.27
Video Laryngoscopes
A wide variety of VLs offer alternatives to direct lar-
yngoscopy and have been the topic of multiple publi-
cations and research.30
Some hospitals in Europe have
moved to ‘universal videolaryngoscopy’ in recent years,
thereby replacing their standard direct laryngoscopes
with VLs for all intubations.31,32
Although this is not
the case in most institutions across Australia and New
Zealand, the use of VLs seems to be increasing, and
their immediate availability is now considered a stan-
dard of care in most hospitals. Even though a large
number of reports in this study (99, 58.2%) described
the use of at least one type of VL during their airway
management, a significant percentage did not describe
the use of a VL as part of their airway strategy at all.
There is evidence that videolaryngoscopy improves the
view and intubation success when direct laryngoscopy
fails while reducing intubation difficulties and
trauma.30
However, in this cohort the use of a VL
was not successful in nearly a third of the attempts
(31 of 99). Difficulties visualising airway structures,
equipment failures and the unsuccessful use of intro-
ducer adjuncts were commonly described in these inci-
dents. Often the VL was used as a rescue device after
multiple other upper airway attempts had failed. The
data were collected from 2009 until 2016, some at a
time where the routine use of VLs was still in its devel-
oping stages. The authors speculate that inexperience
and lack of immediate availability contributed to this
high number of late and consequently failed VL
attempts.
Fibreoptic intubation
In the past, AFOI was regarded by many as the gold
standard technique for difficult airway management.2

Since the introduction of VLs, the use of awake trache-
al intubation techniques seems to have declined. The
NAP4 audit also described multiple events where an
AFOI was not performed when indicated.14
Failure
rates from 1.5% to as high as 11%33–36
have been
reported in various studies. Of all the incidents in the
current report, 47 (27.6%) involved the use of a
fibreoptic technique and a third of all the fibreoptic
intubation attempts failed. The majority of the fibreop-
tic intubations were performed unplanned and asleep
during unexpected difficult airway management.
During difficult intubation and airway rescue, the high-
est success rates were reported when a laryngeal mask
functioned as a conduit for the fibreoptic scope. This is
in line with the current literature, reporting success
rates of up to 98% for this technique.37
However,
some reporters encountered difficulties during this
technique, including cuff damage and inability to
advance the endotracheal tube into the trachea, requir-
ing multiple attempts until successfully securing the
airway. The reporters decided to perform an elective
FOI only in a small number of incidents, of which
five failed. Four of these five were performed with the
patient anaesthetised, of which one required rescue by
an ear, nose and throat surgeon, another two had to be
woken up and one required rescue intubation using
direct laryngoscopy.
There was only one failure of an elective AFOI,
when the patient regurgitated and vomited during
unsuccessful attempts and had to be rescued using an
RSI with a VL technique. It appears there may be a
reluctance to perform AFOI. It is possible that limited
exposure to AFOI during anaesthesia training and the
increased availability and comfort in the use of VL
(and the resulting unfamiliarity with the technique)
may explain its reduced use. Similar trends had been
reported in Europe, which has led to the recent devel-
opment of guidelines for awake tracheal intuba-
tion.35,36
These findings suggest the need for more
frequent practical education sessions in the use of
both asleep and awake FOI techniques.
Remote areas
The lack of advanced airway equipment, including VL,
especially in remote areas, was mentioned in several
incidents. A current ANZCA recommendation is that
all anaesthetising locations should have immediate
access to adequate emergency airway equipment wher-
ever airways are managed.38
A flexible bronchoscope
including a portable light source is recommended to be
available within five minutes.38
As many difficult air-
ways are unpredictable, it is the authors’ opinion that
VL equally should be immediately available in remote
locations. A lack of essential basic airway equipment,
including stylets and bougies, was mentioned when
airway management was performed out of the theatre
as, for example, in the emergency department,
gastroenterology or radiology unit and neonatal ICU.
Outcomes of difficult and failed intubation
The reports indicate the majority of incidents resulted
in no harm (37.6%) or only minor harm (44.7%).
However, 12.4% of incidents resulted in moderate
harm, 3.5% in severe harm, and there were three
deaths.
Hypoxia 85% and cardiopulmonary resuscitation
(CPR):
A total of 40 patients (23.5%) suffered from hypoxia
below 85% during their airway incident. Of these, four
required CPR and one died. More than half of the
patients who suffered from hypoxia below 85% had
no or only minor sequelae at the time of reporting.
Four patients developed cardiac arrhythmias requiring
CPR. Two of these patients presented already in extre-
mis due to multiple injuries, sepsis and multi-organ
failure. The other two were paediatric patients, one
with underlying congenital cardiac disease. Severe hyp-
oxia was frequently present in patients who died in the
NAP4 audit14
and various patient outcomes ranging
from severe harm and death to full recovery without
sequelae were reported. The NAP4 audit reassuringly
estimates death from airway management as 1 in
180,000.14
Death
Although three patients died, only one death was likely
due to failed airway management. The patient pre-
sented for an after-hours emergency procedure. An
RSI was performed but failed and the patient regurgi-
tated and aspirated. The anaesthetist reporting this
incident had been on prolonged duty and considered
this to be a contributing factor to the incident.
Aspiration remains a feared occurrence in anaesthetic
practice and has just recently again been reported as
being associated with significant harm and death.16
ANZCA has also recently released a professional doc-
ument highlighting the importance of fatigue
management.39
Limitations
WebAIRS is a voluntary de-identified incident report-
ing system. Data are collected via tick-boxes and nar-
rative text boxes from entries by anaesthetists across
Australia and New Zealand. The tick-box entries
allow for rapid data extrapolation and the narratives
allow the assessors to understand the event properly
and in more detail. Although the combination is
Endlich et al. 9

expected to provide a complete picture of an incident,
the entry fields in webAIRS are not mandatory and it is
possible some information is not entered. Similar to
other incident reporting systems, it is difficult to collect
accurate denominator data representing the Australian
and New Zealand surgical population. Denominator
data were not collected by webAIRS and the numera-
tor data were submitted voluntarily, which precluded
absolute risk calculations. The webAIRS database was
used as a source of surrogate denominator data. A lim-
itation of this approach is that the denominator data in
the webAIRS database may not necessarily be compa-
rable with the wider surgical population.
Conclusions
Despite advances and significant developments in
airway management strategies, difficult and failed intu-
bation incidents still occur. The data indicate that not
all incidents are predictable, nor are all of them pre-
ventable. Difficult and failed airway management can
occur in any patient age and with any ASA PS. Patients
with a BMI 30 kg/m2
and those undergoing emergen-
cy procedures appear to have a higher risk of difficult
or failed intubation incidents. Human factors, lack of
planning, lack of checking equipment, fatigue, poor
communication and teamwork issues continue to be
contributing factors. Although increased BMI and the
emergent nature of specific procedures remain unmod-
ifiable in the acute setting, attention to preoperative
assessment, improving ease of access to past medical
and anaesthetic history and the adoption and mainte-
nance of equipment standards are all within the pur-
view of anaesthetists and their organisations to
improve planning, preparation and, fundamentally,
the execution of difficult airway management.
Author contribution(s)
Yasmin Endlich: Formal analysis; Investigation; Methodology;
Writing-original draft; Writing-review editing.
Julie Lee: Formal analysis; Investigation; Methodology;
Writing-review editing.
Martin D Culwick: Formal analysis; Investigation;
Methodology; Supervision; Writing-review editing.
Declaration of conflicting interests
The author(s) declared the following potential conflicts of
interest with respect to the research, authorship, and/or pub-
lication of this article: MC is Medical Director of the
Australian and New Zealand Tripartite Data Committee
(ANZTADC). YE is a committee member of ANZTADC.
No conflicting interests exist for the remaining authors.
Funding
The author(s) disclosed receipt of the following financial sup-
port for the research, authorship, and/or publication of this
article: The webAIRS database is jointly funded by the
ANZCA, the Australian Society of Anaesthetists and the
New Zealand Society of Anaesthetists. The present study
received no additional funding.
ORCID iDs
Yasmin Endlich https://orcid.org/0000-0002-8804-4168
Julie Lee https://orcid.org/0000-0002-6896-5568
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Endlich et al. 11

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