Epinephrine in field no help after out-of-hospital cardiac arrest?
Akihito Hagihara et al present suggestive data in the March 21 JAMA that giving epinephrine to people with out of hospital cardiac arrest increases their chances of making it to the hospital with a pulse, but not of making it home with decent brain function or functional status.
In a prospective observational analysis of 417,000 patients with out of hospital cardiac arrests in Japan 2005-2008:
Those who got epinephrine had an 18.5% chance of return of spontaneous circulation prior to hospital arrival (2,786 of 15,030). However, only 5% survived for one month, and only 1.5% made it out of the hospital without severe brain damage and high dependence (i.e. nursing home needs). Among survivors, this was about a 25% rate of neurological outcomes (slightly less depressing).
Those who did not get epinephrine only got their pulse back before hospital arrival 5.7% of the time (23,000 of 402,000), and had about the same one month survival (4.7%), with a 2% chance of good or moderate cognitive performance and a 2% chance of not needing a nursing home. This was about a 40% rate of good neurologic outcome among survivors.
There was a change in guidelines in Japan in 2006 that allowed EMS to administer epinephrine in the field, permitting the above comparisons to be made.
Multiple imperfect previous studies, including two randomized trials [1, 2], have suggested that epinephrine does not improve survival in out of hospital cardiac arrest. As with any critical care research question, patient heterogeneity, complexity of illnesses and care delivery systems make confounders hard to control for, and extrapolation to other health systems difficult.
Akihito Hagihara et al. Prehospital Epinephrine Use and Survival Among Patients With Out-of-Hospital Cardiac Arrest. JAMA 2012;307:1161-1168.