In 2011 the U.K. Royal College of Anaesthetists and The Difficult Airway Society released a report called NAP4 – the 4th national audit of major complications of airway management.
Full text of NAP4 report
The report covered airway complications that occurred in anaesthesia, ICU, and ED settings (approximately 20000 in total). Every reported complication of airway management was analysed for causes and learning points.
The findings relating to ED complications have direct implications for prehospital airway management.
‘Take-home’ messages relating to ED airway management:
- in the event of an airway complication (most commonly failed RSI), patients were more likely to die in ED or ICU than OR
- at-risk patients were often not identified prior to the attempt at airway management
- waveform quantitative capnography should be the standard of care for EVERY intubation
- situations where the capnography reading was zero (indicating misplaced or completely obstructed ETT) were incorrectly attributed to cardiac arrest (CPR always generates SOME CO2)
- complications arose when there was a ‘failure to plan for failure’
- obesity was a major risk factor for airway complications
and, most importantly:
- in the event of a surgical airway being needed, surgical cricothyroidotomy was almost universally successful, while needle cricothyroidotomy had a failure rate of up to 60%
- the success of surgical cricothyroidotomy included those where ED doctors (not surgeons) were the ones performing the procedure
Here is an excellent podcast – it is an interview by Cliff Reid of Jonathan Benger, a Professor of Emergency Medicine and one of the authors of the NAP 4 study (sourced from emcrit.org) regarding the implications of NAP4 for emergency department airway management.
So what are the implications for our HEMS service?
The most relevant findings for us form NAP4 are the findings relating to airway complications in ED, more so than anaesthesia or ICU. Patients who we would intubate pre-hospital are those who, if prehospital intubation were not available, would be intubated shortly after arrival in ED. The majority of our doctors are ED-trained, and are most familiar with ED airway management (translation: simple, fast, relatively low-tech, with the fairly standardised approach for the majority of our patients)
Bringing ED airway management to the prehospital arena has its challenges. The patients are more undifferentiated, comparatively under-resuscitated, and there may not have been enough time to get a sense of their ‘trajectory’.Environmental factors (light, weather, physical access to patient) will have a huge impact on the execution of airway intervention. We have a lot less equipment – no Glidescope, less rescue devices, and no telephone to call for an anaesthetist and a tech with a trolley full of difficult airway equipment. We may have team members (relatively junior ambulance staff, for example) who have much less experience with RSI than ED nurses who are often part of our RSI team.
Doing the basics right therefore becomes even MORE important:
- equipment must be effective, functional, and familiar to us through training
- there must be a ‘shared mental model’ – including a plan for success and a plan for failure – which must be vocalised for every patient with all team members understanding their role
- we must actively consider patient specific elements that will affect the plan for success and the plan for failure (anatomy, injury, obesity etc)
- we must be as prepared as possible – if the situation allows, taking several extra minutes to optimise positioning, place nasal cannulae for apnoeic ventilation etc may be crucial
- we can overcome the disorienting effect of unfamiliar/unfriendly environments by using our RSI checklist – this was we are unlikely to forget something crucial (like capnography)
- there must be a relatively ‘hands off’ team member whose task is to maintain situational awareness – in particular to initiate the ‘plan for failure’ should it become necessary
- in the event of ‘can’t intubate, can’t ventilate‘, a surgical cricothyroidotomy should probably be our ‘go-to’ surgical airway of choice. If needle cricothyroidotomy has a failure rate of up to 60% in a hospital setting, it is hard to imagine how it could fare better in the prehospital arena. Of course there may be exceptions to this (difficult neck anatomy etc)
More commentary on the results and implications of NAP4 can be found here (British Journal of Anaesthesia, section of report relevant to ED and ICU) and here (from Cliff Reid)