Literature Review: Prehospital Epi for Cardiac Arrest

Hagihara A, Hasegawa M, Abe T, et al. Prehospital epinephrine use and survival among patients with out-of-hospital cardiac arrest. JAMA 2012 Mar 21; 307(11): 1,161–8.

Abstract

The objective was to evaluate the association between prehospital epinephrine use and short- and long-term mortality in patients with cardiac arrest. Design—Prospective, nonrandomized, observational propensity analysis of data from 417,188 prehospital EMS-treated adult OHCAs, 2005–2008, in Japan. Main Outcome Measures—ROSC before hospital arrival, survival at 1 month after cardiac arrest, and survival with good or moderate cerebral performance (Cerebral Performance Category [CPC] 1 or 2).

Results—ROSC before hospital arrival was observed in 18.3% of propensity-matched patients in the epinephrine group and 10.5% in the no-epinephrine group (P < .001). One-month survival was 5.1% with epinephrine and 7.0% without; CPC 1–2 was 1.3% with epinephrine 3.1% without (P <.001). A positive association was observed between prehospital epinephrine and ROSC (adjusted OR, 2.51; P < .001). In contrast, negative associations were observed between prehospital epinephrine and long-term outcome (adjusted ORs: 1-month survival, 0.54 [95% CI, 0.43–0.68]; CPC 1–2, 0.21 [95% CI, 0.10–0.44]; both P < .001). Conclusion—Use of prehospital epinephrine was significantly associated with an increased chance of ROSC but decreased chance of survival and good functional outcomes 1 month after the event.

Comment

Epinephrine has been one of the foundations of cardiac arrest treatment for 50 years. While other medications have come and (mostly) gone (e.g., bretylium, lidocaine, atropine), few have questioned the importance of epinephrine. However, even though many would argue that epinephrine is a “standard of care,” its effectiveness has never been established. We do know, and it was confirmed again here, that epinephrine will increase coronary perfusion pressure and the likelihood of ROSC. But the more important question is whether it will result in more patients walking out of hospitals and returning to their families. This study says it does not.

There are two main limitations. First, the study is retrospective, so although the statistical analysis was detailed and complete, there is always the possibility there were differences in the epinephrine and no-epinephrine groups that could explain the differences in outcomes. The second is that there may have been variability in in-hospital care, such as the use of therapeutic hypothermia, which was not measured.

The greatest value of this study is not that it provides the definitive answer on whether to use epinephrine—which it does not—but that it raises the question. It has been difficult to prospectively study epinephrine by randomizing patients to epi and no-epi groups because of concerns that not giving it would be considered unethical. With this new information, critically important prospective studies can be done.

Angelo Salvucci, Jr., MD, FACEP, is medical director for the Santa Barbara County and Ventura County (CA) EMS agencies and a member of the EMS World editorial advisory board.