What've They Done?
Similar to previous NAPs they used local co-ordinators at each hospital through the UK to collect and feedback any reports of AAGA over a period of 12 months (1st June 2012 – 31st May 2013). This was then compared against a ‘denominator’ survey that attempted to get an idea of the total number of anaesthetics being performed. Reporting of awareness was a completely passive process (i.e. patients weren’t specifically questioned about it) though there were efforts to increase the publicity of the study to ensure that other non-anaesthetist healthcare professionals that received reports of awareness (e.g. GPs, psychiatrists) might feedback to the local co-ordinator.
What Did They Find?
The baseline activity survey provided an estimate of 2.8 million anaesthetics given during this period to act as the denominator. As such, this gave an approximate incidence of awareness of about 1 in 19,000 anaesthetics (depending on the strictness of inclusion criteria). Even if the most pessimistic interpretation of the data was employed (with all the reports of indeterminable nature being assumed to be definite awareness) this worked out at an incidence of 1 in 12,000 anaesthetics.
These numbers do seem some way from previously quoted values (in a good way), though I think it is upon closer inspection of the events where some interesting points can be found.
There are many more facets of awareness and risk factors that I won’t transcribe here for the sake of brevity, but the very high obstetric incidence is particularly notable, though many of the risk factors seem to be a combination of several non-obstetric ones in one big helping (lower/different dosing, larger patients, difficult airways and emergency situations). I'm not quite convinced that the choice of drugs plays a role in awareness, rather that they are an artefact of the scenarios they are most commonly used (thio in RSI), but it does call for a pause for thought as your calculate your thio induction dose.
Firstly, we are generally doing a great job with regards to AAGA. As one of the most feared complications for patients and anaesthetists, the incidence is reassuringly low. Though it might be less headline grabbing than the converse, audits confirming good care are just as important as those demonstrating gaps.
Secondly, and I think most importantly, the recommendations highlight an important tenet of anaesthesia (despite my facetious remarks for comic effect). It’s not about the fancy kit, dramatic procedures and experimental techniques; it’s about being meticulous with the basics. Humans make mistakes and always will, and it is essentially a numbers game. I’ve started viewing more and more of my practice as windows for different slips and lapses to creep in and risk affecting my patient. We can probably get away without twitching patients most of the time, but that 1 in 19000 ratio gets smaller. Giving reversal agent is a bit of extra faff, but that ratio gets smaller still. Premixed cefuroxime next to my thio is unlikely to cause problems, but my odds are getting pretty small now. We’ve got a margin for error with awareness most of the time, but I like as many safety nets as I can have, and I doubt our patients would object to this. And I think that is what NAP-5 is all about.