Epinepherine remains a common part of resuscitation care for cardiac arrest, despite a lack of clinical evidence to suggest it improves patient survival.  This study was a retrospective cohort of patients in Japan with witnessed out-of-hospital cardiac arrest.  From this cohort, 1990 matched pairs of patients with initial rhythm of ventricular tachycardia or ventricular fibrillation (VT/VF) and 9058 pairs with non-VT/VF were created on the basis of the propensity for administration of epinephrine by emergency medical services.  The outcome was survival and neurological status at one month or at discharge.  In the propensity matched analysis, epinephrine was associated with greater survival in patients with VF/VT (17.0% versus 13.4%; adjusted odds ratio [OR] 1.36, 95% confidence interval [CI] 1.13 – 1.63) and in patients with non-VF/VT arrest (4.0% versus 2.4%; adjusted OR 1.78, 95% CI 1.49 – 2.13).  The difference in neurologically intact survival was not significant for VF/VT (6.6% versus 6.6%) or non-VF/VT arrest (0.7% versus 0.4%; adjusted OR 1.55, 95% CI 0.99 – 2.41).

Conclusion

Administration of pre-hospital epinephrine for witnessed cardiac arrest is associated with increased overall survival in this propensity matched observational study.  However, given the lack of association with neurologically intact survival, questions remain as to whether epinephrine improves outcomes that are desired by patients.  Randomized study of this important question is warranted.

 Summarized by Steven M. Bradley and Preston M. Schneider

• Nakahara S, Tomio J, Takahashi H, et al. Evaluation of pre-hospital administration of adrenaline (epinephrine) by emergency medical services for patients with out of hospital cardiac arrest in Japan: controlled propensity matched retrospective cohort study. BMJ. 2013;347.