Intraosseous route for out-of-hospital cardiac arrest linked to lower outcomes than intravenous access

This publication is a systematic review and GRADE meta-analysis of observational studies. The population consisted of 245,132 patients experiencing out-of-hospital cardiac arrest. The setting was the out-of-hospital environment. The intervention was intraosseous (IO) vascular access, and the comparator was intravenous (IV) vascular access. The review synthesized data on multiple primary outcomes, including return of spontaneous circulation, sustained return of spontaneous circulation, favorable neurological outcomes at hospital discharge, survival at hospital arrival, survival at hospital discharge, and short-term survival.

The primary outcome results showed that the IO route was associated with a significantly lower return of spontaneous circulation compared to the IV route, with a relative risk (RR) of 0.77 (95% CI: 0.71-0.83, P < .00001; I2 = 84%). For sustained return of spontaneous circulation, the IO route had an RR of 0.87 (95% CI: 0.77-0.97, P = .02; I2 = 53%). Favorable neurological outcomes at hospital discharge were lower with the IO route, with an RR of 0.58 (95% CI: 0.45-0.73, P < .00001; I2 = 81%). Survival at hospital arrival was lower with the IO route, with an RR of 0.79 (95% CI: 0.72-0.86, P < .00001; I2 = 49%). Survival at hospital discharge was lower with the IO route, with an RR of 0.59 (95% CI: 0.45-0.78, P < .0002; I2 = 95%). Short-term survival was lower with the IO route, with an RR of 0.52 (95% CI: 0.32-0.86, P = .010; I2 = 72%).

The review did not report key secondary outcomes. Safety and tolerability findings were not reported, including adverse events, serious adverse events, and discontinuations. The certainty of the evidence was not reported. The review did not compare these results to prior landmark studies in this therapeutic area, as no specific prior studies were cited in the input.

Key methodological limitations and potential biases were not reported in the input. The review is a synthesis of observational data, and causality cannot be inferred. The high I2 values indicate substantial heterogeneity across studies, which may affect the reliability of the pooled estimates.

Clinical implications from the practice relevance note state that the IV route should be preferred in emergency resuscitation protocols when feasible. This suggests that, based on the observed associations, clinicians might prioritize IV access over IO access during out-of-hospital cardiac arrest resuscitation when both options are available.

Key questions remain unanswered. The review did not report on specific patient subgroups, such as those with difficult IV access, or on the impact of different IO insertion techniques. The mechanisms behind the observed associations are not elucidated, and the review did not explore potential confounders or effect modifiers. Future research is needed to address these gaps and to clarify the role of IO access in specific clinical scenarios.