Rapid epinephrine administration improves early outcomes in out-of-hospital cardiac arrest

Introduction: Early administration of epinephrine (Epi) improves outcomes in animal models of cardiac arrest, but there is limited time-dependent clinical data regarding its benefit.

Objective: Our objective was to assess whether timing of Epi administration was associated with improved outcomes after out of hospital cardiac arrest (OHCA).

Methods: We performed a retrospective analysis of a cardiac arrest database from a suburban EMS system from November 2005 to April 2011. Data was abstracted from EMS run sheets, including drug treatment, route and timing of drug administration, and other Utstein variables. Our primary outcome was return of spontaneous circulation (ROSC). Secondary outcomes measured were survival to hospital admission and discharge. For analysis, data were dichotomized according to timing of Epi administration: early Epi group (defined as 911 call to Epi administration of ≤10 min) and late Epi group (>10 min). Further, exploratory analyses were conducted looking at subgroups sorted by initial rhythm and whether the arrest was witnessed. Wilcoxon rank sum tests, chi-square tests, 95% confidence intervals, and multi-variable regression were used for statistical analysis.

Results: We reviewed 809 patients from study communities: 123 patients were excluded, leaving a sample size of 686 for study analysis. The mean time from 911-Epi was 14.3±5.5 min, with 155 (22.6%) receiving early Epi. Key arrest and treatment characteristics were similar between groups. Patients who received early Epi were more likely to have ROSC (32.9% vs. 23.4%, OR 1.59 (1.07, 2.38)), however, no significant increase in survival to admission or discharge was observed. Patients with an initial rhythm of PEA had an increased rate of ROSC (48.6% vs. 21.5%, OR 3.45 (1.56, 7.62)) but not survival to discharge (5.9% vs. 2.6%), OR 2.35 (0.38, 14.7) with early Epi. In a multivariable analysis of bystander witnessed arrests, early Epi was associated with a higher rate of ROSC (OR 3.20 (1.75, 5.88) but not survival to discharge (OR 1.48 (0.50, 4.36)). No improvement in ROSC or secondary outcomes was noted in patients with other arrest rhythms or un-witnessed arrest with Early Epi.

Conclusions: Within the limitations of our study, this data suggests improved rates of ROSC with early Epi administration during OHCA resuscitation, but this study lacks adequate sample size to demonstrate impact on survival to discharge. Large prospective trials are needed to further delineate the benefit of early Epi administration in OHCA.