Difficult Airway Society Meeting 2024

I’ve trekked over from Australia to attend the Difficult Airway Society meeting this November in London and as a non-anaesthetist, I was curious about how much of the programme I could really relate to. You might know that in Australian Emergency Departments, consultants (FACEMs) undertake much emergency airway management in the ED, particularly in-hours; in my main job at Sydney HEMS we are proud of our commitment to excellence in airway management – you can find our more about the work we do at here.

SGAs, ETTs and Cricoid Pressure

The first talk of day 1 was by Dr Nuala Lucas, on supraglottic airway devices vs endotracheal tubes in elective caesarian sections – so about as far from my practice as it could possibly be! Apparently, though, this is a quite controversial topic in anaesthesia – and while the surgical component of this topic is less relevant to us in the ED and prehospital environment, we do still sometimes need to undertake airway management in pregnant patients, and the talk covered some important dogma-busting about the risk of airway management in this patient group.

In obstetric cases, “difficult” airways are seen at a rate of 1:49, but failed intubation is actually rare (1) . Dr Lucas challenged the audience that the airway of an obstetric patient is not inherently physically or necessarily physiologically difficult, but more often situationally difficult (to borrow a differentiation from my colleague Cliff Reid), requiring management out-of-hours and often by more junior staff. And what about gastric emptying in pregnancy? There are several potential factors which conspire to increase the risk of aspiration in pregnancy – but this study, in contrast to what we believe, found that gastric emptying was only delayed in the first trimester (2) and in second and third trimesters it returned to levels comparable with the general population. They also looked at gastric contents using ultrasound after fasting – and found that even following standard fasting guidelines for caesarian section, a high proportion still had high-risk gastric contents present. Her main take-home for us was to rethink the belief that obstetric patients have difficult airways.

The second speaker of the day was Prof Ellen O’Sullivan on the role of cricoid pressure. She began with a reference to a paper from 1848 (3), telling us that aspiration has been a problem in anaesthesia for many years – with Sellick describing cricoid in 1961 (4) and Stept and Safar describing what we might consider “classic” RSI in 1970 (5), following which it quickly became the standard of care. The Universal Airway Society now has agreed components that describe what constitutes an RSI – and thankfully cricoid pressure does not feature, although you can see it at the bottom of the “optional components” list (6). She made the very valid point that Sellick’s observational study was of such poor quality it would likely not be published today. Her bottom line was that it should be considered discretionary and unfinished business – but not without referencing the Sydney HEMS Prehospital Anaesthesia manual from 2011 (!!) – you can find the most recent version here (no idea where she got the old one!) – https://sydneyhems.com/wp-content/uploads/2024/06/phea-manual-v4.pdf. We haven’t routinely used cricoid since 2011.

Remembering John Hinds

Stridor

The next speaker was Dr. David Vaughan on stridor. His number one recommendation for anaesthetists is that they learn and acquire the skill of nasendoscopy to determine the cause of stridor. Perhaps this is something we can add to our EM skillset as well – especially for us at Sydney HEMS, where we use the Ambu A-Scope for awake nasal intubation, so we have some of these skills already (7).

He also had “5 commandments of stridor“, all of which he debunked

1. Patients with stridor need intubation ASAP – he disagreed with this, advocating for watchful waiting but in a carefully selected location, with good emergency management (O2, monitoring, steroids etc).
2. Awake tracheostomy is a measure of last resort – strong disagreement with this one, arguing that if it is likely to be necessary it should be first not last, allowing best possible conditions
3. ENT for FONA if it all goes wrong – deaths here are usually due to delay over technique and therefore the question is who, arguing that scalpel-finger-bougie is likely faster than ENT rapid tracheostomy, notwithstanding the currency and skillset of anaesthetists, who practice this skill regularly [he asked who in the room had practiced one in the last six months – it was everyone in the room. I can honestly say I did 5 paediatric eFONA practices last week!]
4. Gas induction for adults with stridor – this is the classic teaching, and I’ve definitely done this in a remote location with the support of a GP anaesthetist, and it went well. His argument here was that induction with gas in these patients is slower and takes longer, and asks at what point are you going to abandon gas induction – most likely, when the sats fall, when waking them up would take a long time and therefore when you then administer paralysis to a hypoxic patient rather an an oxygenated patient – so there’s no real advantage to this practice.
5. Don’t cannulate stridulous children – some recent RCT evidence (8) suggests IV induction is safer than inhalation induction in high-risk paediatric patients, pointing out that gas inductions are becoming less common in anaesthetic paediatric practice – and he asks which is more stressful for the child, a cannula or tightly applied facemask? His final assertion is that in these cases you should do what is safest in your hands, with your experience and skillset.

GLP-1 agonists and anaesthesia

Next up – Dr Nicholas Levy on GLP-1 receptor agonists for anaesthetists (I wonder whether he read the recent blog post by Greg Yates? (9)). The drugs cause delayed gastric emptying – but diabetes is associated with gastroparesis AND these patients tend to be obese, further compounding anaesthetic risk. Advice has generally been to stop these drugs before procedures/surgery but half-life is increasing in newer versions of the medications, they often are compounded with insulin (so in stopping them, you are also stopping insulin), and stopping 7 days before your emergency airway management requirement isn’t an option at all – and actually the evidence is pretty thin. The CPOC advice in response to the US advice is reassuring for us as it simply suggests many things we would do routinely in emergency airway management (10).

International challenges

Session 2 kicked off was the international session, beginning with Daniel Perin on behalf of SAM (Society for Airway Management) on context-sensitive airway management. While we think of resource disparities between different nations around the world, the reality of the pandemic was that higher income countries ran into resource challenges they had not faced before – so none of us is immune – and this can also be seen in different approaches to the same clinical challenges seen in different global contexts. This study (11) looked at what anaesthetists understood to be the meaning of “difficult airway guidelines” and found significant differences in their understanding. Countries, hospitals, patients and clinical situations are all different. How can we overcome all of these differences, and bring our global practice closer together in the name of safety? His argument was for “airway leads”, a leader in each hospital and in each shift, building on a foundation of training through simulation – something I think we can extrapolate to ED practice and will probably all agree with.

Critically Ill induction

The next speaker was Prof Tonga Saracoglu, talking about the induction of anaesthesia in the context of critically ill patients – definitely an EM-relevant topic. The “best” induction agent, he argues, is difficult to determine due to the number of complexities and factors influencing each individual clinical scenario. Crucially, there’s no universally accepted “gold standard” for acceptable risk. The ideal agent, one which has quick onset and offset, without adverse effects on physiology, doesn’t exist. His systematic review and meta-analysis are due for publication soon, but essentially it finds no significant differences in mortality in ketamine vs etomidate, ketamine having 1.3x mortality over propofol and etomidate having 1.49x mortality over propofol. I think we would need to have a look at the full manuscript and the papers included to understand more about what these numbers mean (particularly as this paper was about critical illness but included trauma). His take-homes included no ketamine in trauma (due to increased in-hospital mortality) – but again, I want to read this paper myself before taking this at face value.

Teaching airway management

Dr Adam Rehak spoke next, on teaching airway management (in the context of safety). He spoke on his pet peeves as an educator – the airway assessment/planning disconnect, skills teaching not fit for purpose and cognitive aid/algorithm corruption. The problem with airway assessment is that we think of it as deterministic whereas it is probabilistic – and we misunderstand this as a screening tool for risk. Our assessments are usually focused on “intubation” risk markers, rather than physiological risk, and the low positive predictive value of our assessment leads to biases (both availability and confirmation).

This translates to superficial planning – few guidelines help with decision-making once we’ve identified “at-risk” airways. In addition, our plan often fails to include a plan for the failure of that plan (we need strategies rather than plans), and the biases tend to drive status quo management. Lastly, we wear new technology as a suit of armour, which can mean we are deskilled in some of the safety-based skills previously seen among anaesthetists (namely, awake tracheal intubation). Skills are poorly defined; airway skills are more than a set of procedural techniques with human factors contributing to all cases in NAP4 (12) and we don’t clearly define the context of the skills we teach and learn, with the range of skills expanding rapidly (eg hyper angulated blade use, HFNO and combined techniques). This leads to a teaching “lucky dip” for trainees, in which the apprenticeship model is inadequate. Trainees aren’t getting the volume of exposure or practice previously available during training AND the deficit is not being addressed by technical skills workshops (which are variable in content and availability and not mapped to curriculum). Skills, he reminds us, are not learned in a vacuum – they need repeated, deliberate practice; reflection; and application in increasingly novel and challenging situations. The value of non-technical skills can be undermined by the prevailing mindset, whether overt (“I don’t believe in non-technical skills”) or covert (“that’s something that happens to other people”).

Lastly, cognitive aids are generally inadequate as they rely on literature review and expert consensus – and the problem is that we usually need tools to bring us back on track, not to tell us what the track is. The tools often have literal consideration of human factors and ergonomic design principles and lack design testing in “real world” conditions. This leads to inappropriate use, where we don’t understand the difference between tools for preparation and planning versus real-time/crisis use. Cognitive aids are infrequently combined with training.

So what are his solutions? We can teach/use airway assessment as a screening test and use markers to trigger targeted, multivariate scoring. We need to synthesise information by answering specific questions a(and he referenced the ANZCA tool here (13)). We should involve the patient in their airway management conversation wherever possible. Develop a strategy, not a plan, and think of markers as an opportunity to use a safety-centric technique. We can create curricula involving all skills – not just airway skills – and develop resources depicting human factors and non-technical skills in action. We can build an airway performance pyramid, mapped to the curriculum, in which we are open about vulnerability and embed skills training in a scaffold of increasing complexity. And when it comes to cognitive aids – we need decision-centric tools and iteratively improve our techniques through sim testing, and when we integrate these tools we need to know the purpose of the tool and teach with it.

Airways on the Intensive Care Unit (ICU)

The last talk of the morning session of day 1 was Prof Andy Higgs, Difficult Airway Society Professor, with his keynote, which took us on a whirlwind tour of the updated evidence around airway management in the ICU. Relevant bits for the Emergency Department are that the evidence is evolving that VL is safer than DL, caveats being insufficient mouth opening, unfamiliar device use and possibly soiled airway use (although established SALAD techniques disagree). He also de-emphasises supraglottic airway rescue for patients with “sick lungs”, considering that if we are intubating those patients late, they may not tolerate much “messing about” with their oxygenation and after a single (rather than three) attempts, we should probably move more quickly to FONA (front of neck access). He also felt that for emergency FONA, we should just start with a vertical incision, whether anatomy is palpable or not (simplifying the technique by removing the option of horizontal vs vertical dependent on palpable anatomy).

There was a good discussion about haemodynamic instability following intubation in critically ill patients, with his summary of management being:

1. No fluid bolus in unselected patients
2. Nominate and empower a team member to manage the cardiovascular system ie “if SBP <100, give 1ml of this, you don’t need to ask me”
3. POCUS pre-induction if possible
4. Arterial line if feasible
5. Pre-intubation vasopressor with a very low threshold for this
6. Ketamine as preferred agent (avoid co-induction with other agents)
7. Vasopressor/inotrope at induction
8. Minimal number of intubation attempts
9. Avoid high intrathoracic pressure bagging
10. If head up, return to supine until stable.

This sounds a lot like my practice in retrieval medicine but it’s always good to hear your approach validated by other people!

Ethics of training

The next afternoon session debated the ethics of undertaking various skills for the purposes of training. Many of these were very anaesthetics-specific, but there was an interesting focus on the importance of informed consent among patients when training is undertaken. The overarching theme was that it is unethical to perform procedures purely for training but it is a real challenge to develop and maintain skills in more unusual areas without undertaking them on patients for training. The key then is to scaffold the skill acquisition with online learning, lectures, simulation and then supervised practice on a patient who has been able to provide informed consent. This might be something we need to think about more in the ED, particularly around explaining clearly what the escape plan is – at what point will you stop attempts by the trainee, does this mean you will then step in, and how many times have you performed this procedure yourself (is there anyone else in the department who is better at it than you?).

More snippets on day 1

The last afternoon session was definitely outside the scope of my practice (a debate on the utility of awake tracheostomy for airway management) and day two kicked off with some research presentations, and then a session on HSSIB – the Health Services Safety Investigations Body (14). This is a body in the UK that investigates instances of adverse outcomes and follows a particular ‘Can’t Intubate Can’t Oxygenate’ (CICO) case in the UK it made some recommendations around information sharing, training and skill acquisition/maintenance with regards to advanced airway management techniques and development of plans for patients who have known difficult airways. It’s well worth reading the full report, which you can find here (15).

One of the outcomes for the Difficult Airway Society was the development of their database (the Difficult Airway Registry), which is unlike many airway registries in that its focus is on information sharing between clinicians, such that if you were to encounter a patient with a “difficult airway”, they can be added for other clinicians to access the details for future away management events. The database is due to go live in the next week or so; you can find it here: (16).

Some other nice ideas have come out of the reports, such as Guys’ Tea Trolley Training – it’s a trolley with tea and snacks that is taken around the theatres to offer particular skills training to the department (examples included front of neck access (FONA), ultrasound for regional anaesthesia) – they have managed to train 200 individuals so far, and this is definitely an idea that could be extrapolated to the Emergency Department with a bit of thought and planning.

A/Prof Nicola Disma provided an update on the European Guideline on eFONA in Paediatric patients, an area of particular interest for me as this is something we are working out at Sydney HEMS. The guideline is a collaboration between ESAIC and the British Journal of Anaesthesia and aims to agree on an evidence-based approach for airway management in children <1 year.

The NAP7 report highlights that eFONA is still relatively rare in this patient group and it is hard to quantify the magnitude of CICO situations in this group. eFONA rates have remained static (17). When should eFONA be performed in patients <1 year? The guideline suggests that when oxygenation and ventilation is inadequate and techniques have failed – and what are the options? Rigid bronchoscopy, surgical tracheostomy or ECMO. For many centres, options 1 and 3 are not feasible, which leaves us in the ED with surgical tracheostomy. This is not a percutaneous cricothyroid puncture because the membrane is very small (average 2mm x 2mm in a child <1, accommodating a size 2.0 ETT) and the anatomy is unfavourable to the approach.

A/Prof Disma’s team performed a crossover study (18) in which they taught two techniques (rapid sequence tracheostomy and scalpel bougie tracheostomy ) and aimed to compare the two approaches. They found the scalpel bougie tracheostomy more successful as a technique and developed a kit list for your department such that you should be able to perform the technique if needed. There are two patient groups; those with predictably difficult airways (eg Pierre-Robin sequence), and those with normal airways but who have become difficult through multiple attempts at airway management. His take-home messages – these are definitely HALO procedures, and the procedure may save a life, so we must be prepared for this situation to arise. “The best eFONA is the one you didn’t need to perform.” Children do not die from failed intubation but from inadequate oxygenation and ventilation. In paediatric practice, most difficult airways are predictable -as is difficult bag-valve-mask ventilation and intubation, unless it is us who have made it difficult through repeated attempts (we must avoid this by limiting the number of airway attempts) – and surgical tracheostomy is the eFONA option in young patients (probably under 8yrs). How would this come about in your department?

Dr Reema Nandi spoke about difficult airways in children with known syndromes (in the context of the HSSIB report), and was able to make some more general recommendations around paediatric difficult airway management – recognise the emergency, call for help early, use available tools (ie paediatric specific equipment), involve key teams (anaesthetics, paediatrics, ENT, critical care), do the basic well, and wherever possible prepare and plan in advance. After the event, debriefing with the family and providing information for the family is key. Many of these patients are dealt with in specialist centres but as I always say, children are inherently portable – they can and do turn up at smaller centres, often unannounced.

Safety and old lessons relearned

On day two before lunch, Dr Imran Ahmad spoke about safety – specifically the ongoing challenge of recognising oesophageal intubation (and the importance of capnography) – his first point was that we need to move simple capnography confirmation towards evidence of “sustained exhaled CO₂” (so an etCO₂ trace, not a colourimeter change). He argues we should be focusing on making sure the tube is in the right place at the right time through a two-point check – visual confirmation of the tube passing through the cords with a video laryngoscope and then waveform capnography. He advocated for a two-person check (19), which is what we undertake as part of our RSI practice at Sydney HEMS, in which both the airway operator and assistant confirm together that the tube is in the right place. He also pointed out that since 2015 for first pass success and 2016 for failed intubation (20), we’ve known that Video Laryngoscopy (VL) is superior to Direct Laryngoscopy (DL). So why haven’t we adopted universal VL practice yet? Newer advances are using AI to identify and name structures on the VL screen (and then showed some highly stress-inducing videos of tubes not quite going where they were needed, further confirming in my mind the benefit of our practice to use bougies for 100% of our managed airways).

Dr Ann Miriam Devarathnam spoke about anaesthesia in low-resource environments. She and her husband, a paediatric surgeon, have been doing some incredible work in a small hospital in India over the last 30 years. She took us through some truly confronting airway cases and how they were managed. Her account was inspiring and concluded with a well-earned standing ovation.

The afternoon session was based around some real-life cases, presented to the panel, who were invited to share their thoughts and approaches. It was interesting – but not hugely relevant to the ED (other than to say, that sometimes anaesthetist input is worth its weight in gold!).

That’s all I have from DAS 2024 – if you’re interested in airway management, there’s a World Airway Management Meeting in Florence in Nov 2025…!

References

1. Frequency and Risk Factors for Difficult Intubation in Women Undergoing General Anesthesia for Cesarean Delivery: A Multicenter Retrospective Cohort Analysis https://pubmed.ncbi.nlm.nih.gov/35188971/
2. Gastric emptying in pregnancy and its clinical implications: a narrative review https://www.bjanaesthesia.org.uk/article/S0007-0912(24)00556-7/fulltext#:~:text=for%20Caesarean%20delivery.-,Gastric%20emptying%20is%20decreased%20in%20the%20first,the%20second%20and%20third%20trimesters.&text=•-,Before%20elective%20Caesarean%20delivery%2C%20carbohydrate%20drink%20or%20tea%20with%20milk,compared%20with%20fasting%20or%20water
3. An Unexplained Death: Hannah Greener and Chloroform https://pubs.asahq.org/anesthesiology/article/96/5/1250/40049/An-Unexplained-DeathHannah-Greener-and-Chloroform
4. https://litfl.com/brian-sellick/ https://litfl.com/brian-sellick/
5. Rapid induction-intubation for prevention of gastric-content aspiration https://pubmed.ncbi.nlm.nih.gov/5534675/
6. Universal Guidelines for Rapid Sequence Intubation https://www.universalairway.org/rsi#:~:text=Rapid%20sequence%20intubation%20(RSI)%20is,of%20aspiration%20during%20tracheal%20intubation.
7. https://sydneyhems.com/resources/emergency-action-card/awake-nasal-intubation-nasal-foi/ https://sydneyhems.com/resources/emergency-action-card/awake-nasal-intubation-nasal-foi/
8. Inhalational versus Intravenous Induction of Anesthesia in Children with a High Risk of Perioperative Respiratory Adverse Events: A Randomized Controlled Trial https://pubmed.ncbi.nlm.nih.gov/29498948/
9. Gregory Yates, “GLP-1A toxicity: What do emergency clinicians need to know about drugs like Ozempic® and Wegovy®?,” in St.Emlyn’s, November 24, 2024, https://www.stemlynsblog.org/glp-1a-toxicity-what-do-emergency-clinicians-need-to-know-about-drugs-like-ozempic-and-wegovy/
10. Please see here for CPOC’s response to the American Society of Anaesthesiologists Consensus – Based Guidance on Preoperative Management of Patients (Adults and Children) on Glucagon-Like Peptide-1 (GLP-1) Receptor Agonists https://cpoc.org.uk/cpoc-response-american-anaesthesiologists-consensus
11. How anaesthesiologists understand difficult airway guidelines-an interview study https://pubmed.ncbi.nlm.nih.gov/29299973/
12. NAP4: Major Complications of Airway Management in the United Kingdom https://www.rcoa.ac.uk/research/research-projects/national-audit-projects-naps/nap4-major-complications-airway-management
13. Airway Assessment: https://www.anzca.edu.au/getattachment/eff1ab5d-46cf-46db-95ef-5e65ecb88c26/PU-Airway-Assessment-20160916v1
14. Health Services Safety Investigations Body https://www.hssib.org.uk
15. Advanced airway management in patients with a known complex disease https://www.hssib.org.uk/patient-safety-investigations/advanced-airway-management-in-patients-with-a-known-complex-disease/investigation-report/#3-analysis-and-findings-the-reference-event
16. DAS Difficult Airway Registry https://das.uk.com/dad/
17. Airway management in the paediatric difficult intubation registry: a propensity score matched analysis of outcomes over time https://pubmed.ncbi.nlm.nih.gov/38374968/
18. Emergency front-of-neck access in infants: A pragmatic crossover randomized control trial comparing two approaches on a simulated rabbit model https://onlinelibrary.wiley.com/doi/10.1111/pan.14796
19. A two-person verbal check to confirm tracheal intubation: evaluation of practice changes to prevent unrecognised oesophageal intubation. https://www.bjanaesthesia.org/article/S0007-0912(24)00557-9/abstract
20. Are we there yet? The long journey of videolaryngoscopy into the mainstream https://associationofanaesthetists-publications.onlinelibrary.wiley.com/doi/10.1111/anae.16057