Whilst the 2010 European Resusciation Council (ERC) guidelines confirm ‘There is insufficient evidence to support or refute the use of any specific technique to maintain an airway and provide ventilation in adults with cardiopulmonary arrest.’ They go on to confirm that despite this ‘tracheal intubation is perceived as the optimal method of providing and maintaining a clear and secure airway.’ However, they also point out that without adequate training and experience, the incidence of complications with tracheal intubation can be unacceptably high.
As a result, in some countries, such as the UK, there has been a general move towards the use of supraglottic airway devices in the pre-hospital setting. This has been supported by the Joint Royal Colleges Ambulance Liaison Committee (JRCALC) Airway Working Group, who in 2008 published ‘A Critical Reassessment of Ambulance Service Airway Management in Pre-Hospital Care’, which recommended that ‘The majority of those managing patients’ airways in the pre-hospital setting should be trained to insert a supraglottic airway device instead of a tracheal tube’. The College of Paramedics outlined a number of concerns and reservations with this approach, but despite this, the use of supraglottic airways for OHCA has increased in the UK.
It was therefore interesting to read the recent clinical study published in Resuscitation, entitled ‘Endotracheal intubation versus supraglottic airway insertion in out-of-hospital cardiac arrest’, by Wang et al. The study is a secondary analysis of data from the multi-centre ‘Resuscitation Outcomes Consortium (ROC) PRIMED trial, looking at adult non-traumatic out-of-hospital cardiac arrest (OHCA) receiving successful supraglottic airway (SGA) insertion of the King Laryngeal TubeTM, Combitube®, and Laryngeal Mask Airway, or successful intubation with an endotracheal tube (ETI). It included 10,455 adult OHCA. 8,487 of these received ETI and 1,968 an SGA. The survival to hospital discharge was 4.7% for ETI and 3.9% for SGA.
The results are interesting, but as the authors themselves acknowledge, there are limitations and confounders, including the order of airway device insertion, and the number and duration of insertion attempts. The data was not intended for primary evaluation of airway management techniques, and information regarding interruptions to compressions during insertion of the airway device, ventilation rates or tidal volumes could not be accounted for or was not regarded as reliable. Despite this, the results from this paper are certainly worth further consideration and it is likely will be the subject of significant discussion amongst the Emergency Medicine fraternity and beyond.
Of course, the absolute difference in survival rates in this study was small, and whilst confirming that observational data are clearly of value, an editorial published in the same issue of Resuscitation as this study, ‘ROC, paper, scissors: Tracheal intubation or supraglottic airway for OHCA?’ pointed out that ‘randomised trials are still widely considered to be the gold standard for addressing focused clinical questions’. Indeed, Wang et al themselves confirmed that ‘prospective randomised assignment may represent an optimal strategy for comparing OHCA outcomes between ETI and SGA’.
As reported in an earlier blog post, a randomised trial comparing two SGAs (LMA Supreme® and i-gel®) to ‘current practice’ which it is believed will usually be ETI, is underway in the UK, called the ‘Airway Management Feasibility Study (REVIVE – Airways)’. It is also interesting to note that neither of the two SGAs in the REVIVE study were included in the US study being discussed here. Clearly, results for one SGA cannot be extrapolated to another, so these results are only relevant for the devices studied. Given the considerable differences in design and performance characteristics between the CombiTube®, King Laryngeal TubeTM, standard Laryngeal Mask Airway and the LMA Supreme® and i-gel®, it is possible, perhaps likely, results for the latter two devices would have been quite different.
Whilst we await the results of high quality randomised controlled trials of the use of SGAs for CPR, the conclusion given in the study by Wang et al seems entirely reasonable ‘EMS medical directors must consider patient characteristics, device efficacy and practitioner skill and training when selecting OHCA airway management strategies.’ This approach is echoed by the ERC in their 2010 guidelines ‘There are no data supporting the routine use of any specific approach to airway management during cardiac arrest. The best technique is dependent on the precise circumstances of the cardiac arrest and the competence of the rescuer’. Now you can’t really argue with that.