Comparison of Prehospital Vascular Access Methods and Their Association with Survival in Out-of-Hospital Cardiac Arrest.

Purpose: Out-of-hospital cardiac arrest (OHCA) remains a critical emergency with low survival rates despite advanced prehospital interventions. Emerging evidence suggests that early administration of epinephrine is associated with improved outcomes compared to delayed epinephrine administration, particularly in non-shockable rhythms. While intravenous (IV) access is the standard route for drug delivery, it is often difficult to obtain in the prehospital setting. Intraosseous (IO) access offers a viable alternative, but its comparative survival benefit remains unclear. Few studies have examined the association of IO access on outcomes relative to patients who received no prehospital vascular access. This study aims to assess survival outcomes among OHCA patients receiving different prehospital vascular access strategies. Patients and Methods: This retrospective cohort study included adult patients with non-traumatic OHCA in Taoyuan, Taiwan (June 2021-June 2024). Patients were grouped based on the final attempted route: IV, IO, failed IV, or no-access attempt. The primary outcome was survival to discharge; secondary outcomes were prehospital ROSC, survival over 2 hours, and favorable neurological outcome. Multivariable logistic regression was performed, with sensitivity analyses including early treatment (≤15 min), EMT-P-level providers, and epinephrine stratification. Results: Among 5093 adult OHCA patients, compared with the no-access attempt group, IO access was associated with higher survival to discharge (aOR 1.44; 95% CI 1.08-1.91). IV access also showed increased survival to discharge (aOR 1.25; 95% CI 1.01-1.58). However, in the subgroup analysis of patients treated by EMT-P providers, IV access demonstrated a stronger association with survival to discharge (aOR 3.65; 95% CI 1.16-11.49) compared to IO access (aOR 2.29; 95% CI 1.28-7.24). Failed IV attempts yielded the poorest outcomes. Sensitivity and stratified analyses demonstrated that early vascular access (≤15 min) significantly improved survival for both IO (aOR 2.03; 95% CI 1.45-2.85) and IV (aOR 1.25; 95% CI 1.11-1.49) routes, with treatment timing, provider level, and epinephrine use modifying these associations. Conclusion: Prehospital vascular access, either IV or IO, was associated with improved survival compared with no access attempt. Failed IV attempts were linked to the poorest outcomes, underscoring the potential harm of procedural delays. Early transition to IO may serve as an effective rescue strategy when IV access is difficult; however, successful IV or humeral IO should be preferred when feasible.