Supraglottic airway versus endotracheal intubation shows no overall survival benefit in out-of-hospital cardiac arrest

This systematic review and meta-analysis examined the comparative effectiveness of two advanced airway management strategies in out-of-hospital cardiac arrest (OHCA). The analysis pooled data from eight clinical studies involving a total of 14,797 patients who experienced OHCA. All included studies were conducted in the out-of-hospital setting, primarily by emergency medical services personnel. The population consisted exclusively of patients with OHCA, though specific demographic characteristics, initial cardiac rhythms, or bystander intervention rates were not reported in the meta-analysis summary.

The intervention was the use of a supraglottic airway (SGA) device as the primary advanced airway. The comparator was endotracheal intubation (ETI). The meta-analysis did not specify the exact types of SGA devices used (e.g., laryngeal mask airway, i-gel) or provide details on the specific intubation protocols, including medication use for rapid sequence intubation. Dosing and procedural specifics were not reported, indicating the analysis focused on the broad comparison of the two airway management categories rather than specific techniques or devices within those categories.

The primary outcome was return of spontaneous circulation (ROSC). Overall, the meta-analysis found no significant difference in ROSC rates between the SGA and ETI groups. The risk difference (RD) was 0.02, with a 95% confidence interval (CI) of 0.0 to 0.04 and a p-value of 0.11. Since the CI includes zero and the p-value exceeds 0.05, this indicates no statistically significant effect of airway type on the overall likelihood of achieving ROSC. Absolute numbers for ROSC events in each group were not reported.

A key secondary outcome was survival to hospital discharge. Similar to the primary outcome, the analysis found no significant difference between groups. The risk difference for survival to hospital discharge was 0.01 (95% CI -0.01 to 0.02, p = 0.30). Again, the confidence interval crossing zero and the non-significant p-value indicate no detectable overall survival benefit for either airway strategy. The analysis also performed subgroup analyses based on whether the study protocols included additional training for providers. For ROSC, the subgroup where additional training was provided showed a statistically significant positive effect for SGA, with an RD of 0.02 (95% CI 0.0 to 0.04, p = 0.02). In contrast, the subgroup without additional training showed no significant effect (RD 0.01, 95% CI -0.05 to 0.01, p = 0.72).

The meta-analysis did not report specific data on safety, tolerability, or adverse events. Rates of adverse events such as aspiration, airway trauma, device failure, or misplaced tubes were not provided. Similarly, data on serious adverse events, discontinuations due to complications, or overall tolerability were not reported. This represents a significant gap in the evidence summary, as the comparative safety profile is a critical factor in clinical decision-making for airway management.

These results contribute to an ongoing debate in prehospital care regarding the optimal first-line advanced airway for OHCA. Prior landmark studies and trials have yielded mixed results, with some suggesting equivalence between SGA and ETI, while others have pointed to potential advantages or disadvantages for one strategy over the other, often influenced by provider skill level and system factors. This meta-analysis aligns with the body of evidence finding no clear mortality superiority for either technique overall, reinforcing that factors beyond the specific airway device—such as high-quality chest compressions and early defibrillation—likely have a greater impact on patient outcomes.

Key methodological limitations must be considered. The authors note that training programs differed between the investigated studies, making it difficult to isolate the effect of the device from the effect of the training. Furthermore, while statistical heterogeneity was reportedly not observed, clinical heterogeneity in terms of EMS system characteristics, provider experience levels, and specific protocols was likely present. Most importantly, the test for subgroup differences (comparing the training vs. no-training subgroups) was not statistically significant (p = 0.73). This undermines the reliability of the subgroup finding suggesting a benefit for SGA with additional training, as it indicates the observed difference between subgroups could be due to chance.

The clinical implications are nuanced. For systems and clinicians, the overall finding suggests that in the context of OHCA, the choice between SGA and ETI as the initial advanced airway may not be the pivotal factor determining ROSC or survival. System-level decisions might reasonably prioritize the technique in which local providers can achieve the highest success rate with the shortest interruption in chest compressions. The subgroup analysis, while not robust, hints that investment in structured, additional training for a chosen airway strategy could be more important than the choice of strategy itself. However, this should not be interpreted as evidence that SGA is superior when training is provided.

Several important questions remain unanswered. The lack of safety and adverse event data prevents a complete risk-benefit assessment. The optimal type and duration of 'additional training' are undefined. The impact of specific SGA device types (e.g., second-generation versus first-generation) compared to ETI is unclear. Furthermore, outcomes such as neurologically intact survival were not reported in this analysis, leaving a critical patient-centered endpoint unaddressed. Future research should focus on standardized training packages and report comprehensive safety outcomes to guide more definitive clinical and policy recommendations.