Epinephrine for out-of-hospital cardiac arrest may hurt long-term outcomes

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Adrenaline may jumpstart the heart but it might not contribute positively to survival following an out of hospital cardiac arrest (OHCA), found a study published Dec. 9 in the Journal of the American College of Cardiology.

Patients whose successful return of spontaneous circulation (ROSC) was owed to epinephrine (adrenaline) did poorly compared with those who did not require its use, researchers noted.

Florence Dumas, MD, PhD, of the emergency department at Cochin-Hotel-Dieu Hospital in Paris, and colleagues studied trends at a large local cardiac arrest center between 2000 and 2012. The hospital collected data in an ongoing registry of all patients admitted with ROSC and an OHCA. Of 1,556 patients included in the study, 31 percent survived to hospital discharge. Good neurological outcomes occurred for 29 percent of those patients.

Epinephrine was associated with negative outcomes, more so than other predictive factors. Odds of favorable neurological outcome following prehospital epinephrine use were less than one-third of those who did not receive it, regardless of hospital interventions. However, two factors increased that risk: time intervals between collapse and first use of adrenaline and the amount of epinephrine used. The more time before epinephrine was used and the higher the dose, the odds of intact survival decreased.

Patients who received epinephrine 22 minutes or more after a cardiac arrest had slim odds of a better outcome at 0.17, while at nine minutes post-OHCA, those odds were 0.54. The dose response placed poorer odds on higher doses: at 1 mg of epinephrine, patients had odds around 0.48. At 2 to 5 mg, patients had odds for positive neurological survival around 0.3, while 5 mg or more brought odds down to 0.23.

This translated to 17 percent of patients given epinephrine to revive circulation prior to arrival at the hospital surviving with good outcomes, while 64 percent of patients who had return of circulation without epinephrine survived with good outcomes.

These findings coincided with other observations of epinephrine use to assist with OHCA.

Dumas et al suggested that these findings should provoke further study into resuscitation and how treatment at different phases may interact with later recovery. In particular, they determined that careful study and understanding of how both dose and timing affect outcomes in the metabolic phase of resuscitation may improve clinical practice and assist more patients achieve positive outcomes.