Effectiveness of Prehospital Epinephrine Administration in Improving Long-term Outcomes of Witnessed Out-of-hospital Cardiac Arrest Patients with Initial Non-shockable Rhythms.

OBJECTIVE

We evaluated the association between prehospital epinephrine administration by emergency medical services (EMS) and the long-term outcomes of out-of-hospital cardiac arrest (OHCA) with initial pulseless electrical activity (PEA) or asystole.

METHODS

We conducted a controlled, propensity-matched, retrospective cohort study by using Japan's nationwide OHCA registry database. We studied 110,239 bystander-witnessed OHCA patients aged 15-94 years with initial non-shockable rhythms registered between January 2008 and December 2012. We created 1-1 matched pairs of patients with or without epinephrine by using sequential risk set matching based on time-dependent propensity scores to balance the patients' severity and characteristics. We compared overall and neurologically intact survival 1 month after OHCA between cases and controls using conditional logistic regression models by category of the initial rhythm.

RESULTS

Propensity matching created 7,431 pairs in patients with PEA and 8,906 pairs in those with asystole. Epinephrine administration was associated with higher overall survival (4.49% vs. 2.96%; odds ratio [OR], 1.55; 95% confidence interval [CI], 1.30-1.85) but not with neurologically intact survival (0.98% vs. 0.78%; OR, 1.26; 95% CI, 0.89-1.78) in patients with PEA, and with higher overall survival (2.38% vs. 1.04%; OR, 2.34; 95% CI, 1.82-3.00) and neurologically intact survival (0.48% vs. 0.22%; OR, 2.28; 95% CI, 1.31-3.96) in those with asystole.

CONCLUSIONS

Prehospital epinephrine administration by EMS is favorably associated with long-term neurological outcomes in patients with initial asystole and with long-term survival outcomes in those with PEA.