Lower-dose epinephrine administration and out-of-hospital cardiac arrest outcomes

Abstract

BackgroundInternational guidelines recommend administration of 1 mg of intravenous epinephrine every 3–5 min during cardiac arrest. The optimal dose of epinephrine is not known. We evaluated the association of reduced frequency and dose of epinephrine with survival after out-of-hospital cardiac arrest (OHCA). MethodsIncluded were patients with non-traumatic OHCA treated by advanced life support (ALS) providers from January 1, 2008 to June 30, 2016. During the before period, providers were instructed to give epinephrine 1 mg intravenously at 4 min followed by additional 1 mg doses every eight minutes to patients with OHCA with a shockable rhythm and 1 mg doses every two minutes to patients with a non-shockable rhythm (higher dose). On October 1, 2012, providers were instructed to reduce the dose of epinephrine treatment during out-of-hospital cardiac arrest (OHCA): 0.5 mg at 4 and 8 min followed by additional doses of 0.5 mg every 8 min for shockable rhythms and 0.5 mg every 2 min for non-shockable rhythms (lower dose). Patients with shockable initial rhythms were analyzed separately from those with non-shockable initial rhythms. The primary outcome was survival to hospital discharge with a secondary outcome of favorable neurological status (Cerebral Performance Category [CPC] 1 or 2) at hospital discharge. Multiple logistic regression modeling was used to adjust for age, sex, presence of a witness, bystander CPR, and response interval. Results2255 patients with OHCA were eligible for analysis. Of these, 24.6% had an initially shockable rhythm. Total epinephrine dose per patient decreased from a mean ± standard deviation of 3.4 ± 2.3 mg–2.6 ± 1.9 mg (p < 0.001) in the shockable group and 3.5 ± 1.9 mg–2.8 ± 1.7 mg (p < 0.001) in the non-shockable group. Among those with a shockable rhythm, survival to hospital discharge was 35.0% in the higher dose group vs. 34.2% in the lower dose group. Among those with a non-shockable rhythm, survival was 4.2% in the higher dose group vs. 5.1% in the lower dose group. Lower dose vs. higher dose was not significantly associated with survival: adjusted odds ratio, aOR 0.91 (95% CI 0.62–1.32, p = 0.61) if shockable and aOR 1.26 (95% CI 0.79–2.01, p = 0.33) if non-shockable. Lower dose vs. higher dose was not significantly associated with favorable neurological status at discharge: aOR 0.84 (95% CI 0.57–1.24, p = 0.377) if shockable and aOR 1.17 (95% CI 0.68–2.02, p = 0.577) if non-shockable. ConclusionReducing the dose of epinephrine administered during out-of-hospital cardiac arrest was not associated with a change in survival to hospital discharge or favorable neurological outcomes after OHCA.