OBJECTIVE: To summarise evidence on the clinical effectiveness of initial vascular attempts via the intraosseous route compared to the intravenous route in adult cardiac arrest. METHODS: We searched MEDLINE and Embase (OVID platform), the Cochrane library, and the International Clinical Trials Registry Platform from inception to September 4th 2024 for randomised clinical trials comparing the intraosseous route with the intravenous route in adult cardiac arrest. Our primary outcome was 30-day survival. Secondary outcomes included favourable neurological outcome at 30-days/ hospital discharge and return of spontaneous circulation (both any ROSC and sustained ROSC). We performed meta-analyses using a fixed-effect model. We assessed risk of bias using the Cochrane Risk of Bias-2 tool and evidence certainty using the GRADE approach. RESULTS: We included three randomised clinical trials encompassing 9,332 participants with out-of-hospital cardiac arrest. Initial attempts via the intraosseous, compared with intravenous, route did not increase the odds of 30-day survival (odds ratio 0.99, 95% confidence interval 0.84-1.17
9,272 participants
three trials
moderate-certainty evidence) or favourable neurological outcome at 30-days/ hospital discharge (odds ratio 1.07, 95% confidence interval 0.88-1.30
9,186 participants
three trials
low-certainty evidence). The odds of achieving sustained return of spontaneous circulation were lower in the intraosseous group (odds ratio 0.89, 95% confidence interval 0.80-0.99
7,518 participants
two trials
moderate-certainty evidence). CONCLUSION: Initial vascular access attempts via the intraosseous, compared with intravenous, route in adult cardiac arrest did not improve 30-day survival and may reduce the odds of a sustained return of spontaneous circulation.