Wednesday 14 November 2018

Supraglottic airway vs. endotracheal tube for out-of-hospital cardiac arrest; which is better?

This study was a large cluster-crossover clinical trial in the USA attempting to answer this research question. 27 EMS agencies were randomized in clusters to either a laryngeal tube or endotracheal tube with crossover to the alternate strategy at 3 to 5 month intervals.

Why randomize EMS agencies? Wouldn’t it be better to randomise individual patients?

Think feasibility.

Research in cardiac arrest is challenging.  The last thing paramedics want to do during a code is open a study envelope. They’ve got other things on their minds. Hence randomise EMS agencies. Of course this can introduce bias and statistical inefficiency. But such is compromise in research.

The primary outcome was 72-hour survival. They did report the much more important outcome of favourable neurologic status (mRS<3) at discharge from hospital.


3000 patients were enrolled. About half were unwitnessed and/or had no bystander CPR. 80% had non-shockable rhythms. It’s no surprise overall outcomes were terrible. It is also challenging to demonstrate a difference in treatment strategies when the vast majority were going to die regardless of intervention. But such is life… and death.

Rates of initial airway success were 90% with the laryngeal tube but a pretty dismal 50% with the endotracheal tube. Yikes!

72-hour survival was 18% with the laryngeal tube and 15% with the endotracheal tube. Rates of favourable neurologic outcome was 7% vs. 5% favouring the laryngeal tube.

What are we to think?

Unfortunately, this study did have some problems. It had poor rates of first pass success with intubation. The pragmatic study design and cluster randomisation introduced noise. They only studied one type of supraglottic airway… i.e. not the LMA.

But in the end, there probably is no compelling reason to push for endotracheal intubation in the field. This may distract from other meaningful interventions such as good quality CPR and rapid defibrillation.

It’s unclear how much of this is externally valid to a well-resourced Emergency Department. A dedicated airway doctor and lots of hands might change our outlook.  Nevertheless, this study does push our focus away from the endotracheal tube in cardiac arrest.

Image result for laryngeal tube airway 

Wang, HE, Schmicker RH, Daya MR, et al. Effect of a Strategy of Initial Laryngeal Tube Insertion vs. Endotracheal Intubation on 72-Hour Survival in Adults with Out-of-Hospital Cardiac Arrest. JAMA 2018;320(8):769-778. [link to abstract]

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