A secondary study using data from the ROC PRIMED study suggests there could be something to the warnings about using supraglottic airways (LMAs) for airways in out-of-hospital cardiac arrests. Supraglottic airways were associated with increased mortality.

For the last five years or so, the supraglottic airways (SGAs) have increasingly been used as the preferred airway in out-of-hospital cardiac arrests (OHCA).

Then, in early 2012, Resuscitation published a small animal study by Segal et al. demonstrating significantly (15-50%) reduced carotid blood flow in pigs being resuscitated with a SGA for an airway as compared to traditional ETI-resuscitation.

That decreased carotid blood flow could result in increased mortality and worse functional outcome in the OHCA patients who get SGAs instead of traditional endotracheal intubation.

The study, by Segal et al, generated some controversy on the medical blogs. For the most comprehensive and accessible discussion about SGAs in OHCA you should listen to the EMcritpodcast here. Don’t forget to read the comments field.

The study
ROC PRIMED was a large OHCA trial comparing early vs late ECG analysis as well as ITD vs placebo. The trial was stopped early for futility and became yet another huge, expensive and inconclusive cardiac arrest study that remains controversial.  Interestingly, the study protocol did not dictate what airway the EMS were to use. As a consequence there is outcome data from OHCA airway management using both ETI and SGA. The secondary study used that data to explore if the airway used affects outcome.

The secondary analysis included OHCA patients who had successful out-of-hospital airways. Either they had traditional ETI one of three SGAs (King LT, Combitube and LMA). Primary outcome was survival to hospital discharge with a satisfactory functional status, defined as a Modified Rankin Scale score  of 3 or more.

The study identified 8487 (81,2%) successful ETIs and 1968 (18,8%) successful SGAs. Of the SGAs 63% were King LTs, 20,5% were Combitube and 16,6% were LMAs.

Survival to hospital discharge with satisfactory functional status was 4,7% in the ETI group compared to 3,9% in the SGA group. This was considered a moderate association.

There were also stronger associations between ETI and ROSC and 24h survival.

Take home message
Supraglottic airways in out-of-hospital cardiac arrests might actually be associated with increased mortality and worse functional outcomes.

Studies like this have huge limitations. Even so, paying attention might pay off. ALS algorithms have in the past changed as a result of weaker evidence than this.

Resuscitation. 2012 Sep;83(9):1061-1066. Epub 2012 Jun 1. Endotracheal intubation versus supraglottic airway insertion in out-of-hospital cardiac arrest. Wang HE, Szydlo D, Stouffer JA, Lin S, Carlson JN, Vaillancourt C, Sears G, Verbeek RP, Fowler R, Idris AH, Koenig K, Christenson J,Minokadeh A, Brandt J, Rea T; The ROC Investigators.


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5 Responses to SGAS HARM IN OHCA?

  1. Christopher says:

    The most interesting nugget, which was buried in the discussion in the paper, was this:

    In the secondary sensitivity analysis we observed higher survival among patients not receiving any successful advanced airway placement efforts, a finding that has been echoed by other observational studies.

    So if not using an ETI or an SGA sends more people home, why are we quibbling over ETI vs SGA?!

  2. K says:

    Hi Christopher,
    Thanks for highlighting it. I noticed it too. Unsettling to say the least!

  3. John Glasheen says:

    Is that because the higher survival group were EMS witnessed cardiac arrests – the “one shock into perfusing rhythm” type of arrest, therefore didn’t require any advanced airway?


    • Thomas D says:

      Interesting point, and it might be valid. It isn’t explicitly stated in the paper, but it seems the patients included without an airway device in place had an attempt at placing an airway, possibly hinting that these patients were also longer without ROSC (but still did better than the intervention groups).

  4. Chris Wearmouth says:

    Quite a few of these observational studies seem to show no airway intervention>ETI>SGA. I think this is most likely due to the nature of EMS responding to a cardiac arrest. The ‘one shock into rhythm’ patients won’t receive any advanced airway interventions and will obviously do better, but not because someone explicitly chose not to stick a tube down their throat. Likewise, most paramedics will attempt ETI first, only progressing to SGA as a ‘rescue device’ or if they predict a difficult intubation. This means that SGAs will be reserved for those patients who have had a longer down time, or are more difficult to mange e.g. the pharynx is full of blood. It’s therefore unsurprising that in an observational study SGAs will have a poorer survival to hospital discharge! We need a RCT comparing SGA to ETI in the same group of paramedics in the same population, it’s the only way to conclusively prove one way or the other.

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