The optimal vascular access for patients with out-of-hospital cardiac arrest (OHCA) remains controversial. Increasing evidence supports intraosseous (IO) access due to faster medication administration and higher first-attempt success rates compared to intravenous (IV) access. However, the impact on patient outcomes has been inconclusive.

This retrospective cohort study in Taoyuan City, Taiwan, from January 1, 2019, to December 31, 2022, included patients aged ≥18 years with non-traumatic OHCA resuscitated by emergency medical technician paramedics (EMT-Ps) with either IVs or IOs for final vascular access. The exclusion criteria were cardiac arrest en route to the hospital and resuscitation during the coronavirus pandemic (from May 1, 2022, to October 31, 2022). The primary and secondary outcomes were sustained ROSC (≥2 h) and cerebral performance category (CPC) 1–2, respectively. Univariate logistic regression was used to estimate the odds ratios (ORs) and 95% confidence intervals (CI) for the primary analysis. Multivariable logistic regression was employed, with variables selected based on a p-value of <0.05 in the univariate analysis. The survival benefits of different insertion sites and subgroups like general ambulance teams (with a composition that includes fewer EMT-Ps and limited experience in using IO access) were also analyzed.

A total of 2003 patients were enrolled; 1602 received IV access and 401 IO access. The median patient age was 70 years, and most were male (66.6%). Compared to patients receiving IV access, the adjusted odds ratios (aORs) for primary and secondary outcomes in patients with IOs were 0.83 (95% confidence interval [CI], 0.61–1.11; p = 0.20) and 0.96 (95% CI, 0.39–2.40; p = 0.93), respectively. Different insertion sites showed no outcome differences. In the subgroups of females and patients resuscitated by general ambulance teams, the aORs for sustained ROSC were 0.55 (95% CI, 0.33–0.92; p = 0.02) and 0.62 (95% CI, 0.41–0.94; p = 0.02), respectively.

For patients with OHCA resuscitated by EMT-Ps, IO access was comparable to IV access regarding patient outcomes. However, in females and patients resuscitated by general ambulance teams, IV access might be favorable.