Does the effectiveness of advanced airway management depend on initial cardiac arrest rhythm? A secondary analysis of the pragmatic airway resuscitation trial.

Background: Over 70% of patients with out-of-hospital cardiac arrest (OHCA) present with a non-shockable initial rhythm, asystole or pulseless electrical activity (PEA), which is associated with lower survival than a shockable initial rhythm. Advanced airway management and oxygen delivery are important OHCA interventions, but their impact based on different presenting rhythm groups are incompletely defined. Our objective was to determine if advanced airway strategy is associated with outcomes in shockable, PEA and asystolic OHCA.

Methods: We performed a secondary analysis of data collected from the Pragmatic Airway Resuscitation Trial (PART), which assigned adults with OHCA to a strategy of either endotracheal intubation (ETI) or laryngeal tube (LT) for initial advanced airway management. We stratified patients by initial cardiac rhythm: shockable (ventricular fibrillation/pulseless ventricular tachycardia (pVT), AED shock), PEA or asystole. We excluded AED non-shockable and unknown rhythms. The primary outcome was 72-h survival. Secondary outcomes included return of spontaneous circulation (ROSC) at emergency department arrival, survival to hospital discharge, and survival with good neurological function (modified Rankin score ≤3). We used general estimating equations to determine the associations between airway strategy initial arrest rhythm and outcomes, adjusted for age, sex, witnessed status, and bystander CPR.

Results: There were 3004 patients in the parent trial of which 2847 were included in this analysis. Of these 575 (20.2 %) were shockable, 671 (23.6 %) were PEA, and 1601 (56.2 %) were asystole. Compared with ETI, LT airway use was not associated with improved 72-h survival in shockable rhythms (adjusted [AOR] 1.30 (0.91, 1.67)), PEA (AOR 0.97 (0.65, 1.45)), or asystole (AOR 1.13 (0.79, 1.64)). Similarly, we noted no significant interaction between airway strategy and initial rhythm for the secondary outcomes of ROSC, survival to discharge, and survival to discharge with good neurological function.

Conclusion: Prehospital advanced airway management strategy (ETI vs. LT) was not significantly associated with outcomes regardless of initial cardiac rhythm.