Supraglottic airways versus tracheal intubation for OHCA

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.

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6 thoughts on “Supraglottic airways versus tracheal intubation for OHCA

  1. I wonder if the concentration on high quality CPR is responsible for an increase in the ETI arm of this research. There is no mention of the dependence on US EMS of protocol driven practice, which might skew the results if the majority protocol is ETI. High quality CPR as been the reason for my own witnessed increase in ROSC with my colleagues on the UK. With a roughly equal use of SGA and ETI.

    • Thank you for your comments. You make a very interesting point. As the authors themselves acknowledge, there are a lot of limitations to this study data and a number of potential confounders.

      Wang published another interesting clinical paper in 2011, entitled ‘Out-of-hospital airway management in the United States’. As with the study being reviewed here, ETI was conducted more than 4 times as often as insertion of an SGA, although this was not just for cardiac arrest. The striking aspect of the 2011 study was the low success rate for ETI (77% overall). The data also showed that of the alternative airway devices used, Combitube® was the most popular, and used more than twice as often as a Laryngeal Mask Airway. As you will know, the 2010 UK Resuscitation Council Guidelines state that ‘The Combitube® is rarely, if ever, used in the UK and is no longer included in these guidelines.’ It would have been interesting to see in this latest study by Wang et al, if the survival to hospital discharge would have been the same for one of the newer 2nd generation SGA’s devices more commonly used here in the UK. However, it would seem there is currently little or no data for these devices for OHCA in the US. In the UK, the REVIVE study will provide data for survival to hospital discharge, as well as insertion, ventilation and initial resuscitation success.

      • Unfortunately, as you point out in your blog post, the assumption is that ETI will be ‘normal practice’ in the REVIVE study. If SGA of some other type is predominant in this arm then little will be proved about ETI in OHCA. Surely a limitation to the study?

        Tj.

    • Yes, in such a scenario, I agree, it would be a limitation. However, as this is a feasibility study, with the primary purpose of determining whether the study design will work in practice and provide meaningful data, the protocol can be modified for any subsequent larger scale study if it is concluded the value of the data collected was compromised by this factor.

  2. Pingback: Dispositivos supraglóticos versus intubação traqueal em situação de PCR no pré-hospitalar |

  3. Pingback: The i-gel SGA for prehospital airway management in a UK ambulance service | Dave on Airways

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