Early epinephrine for out-of-hospital cardiac arrest may improve chances of survival
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Later timing of epinephrine administration in out-of-hospital cardiac arrest was associated with poorer chances of survival to discharge, regardless of presence of a shockable rhythm, but findings were not significant, researchers reported.
According to data published in JAMA Network Open, although earlier epinephrine administration was associated with better functional outcomes at hospital discharge in out-of-hospital cardiac arrest (OHCA), later administration correlated with greater likelihood of prehospital return of spontaneous circulation (ROSC).
“The 2020 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations and 2020 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care recommend administration of epinephrine as soon as feasible for individuals with nonshockable cardiac rhythms (strong recommendation with a low certainty of evidence) and suggest administration of epinephrine after initial defibrillation attempts are unsuccessful for shockable cardiac rhythms (weak recommendation with low certainty of evidence),” Masashi Okubo, MD, MS, clinical assistant professor of emergency medicine and ED attending physician at the University of Pittsburgh, and colleagues wrote. “The low certainty of evidence for these recommendations suggests that the optimal timing of epinephrine administration is an existing knowledge gap.”
The analysis included 41,079 individuals who experienced OHCA (median age, 67 years; 65% men); 24.6% of patients initially had shockable rhythms. The primary outcome was survival to hospital discharge.
Survival and timing of epinephrine
Epinephrine was administered to 81.5% of patients with initially shockable cardiac rhythms and 90% of patients with nonshockable rhythms.
Among patients with an initially shockable rhythm, the RR for survival to hospital discharge was highest in those who received epinephrine in the 0- and 5-minute window after emergency medical services (EMS) arrival (1.12; 95% CI, 0.99-1.26); however, the finding was not statistically significant.
When Okubo and colleagues assessed the timing of epinephrine administration as a continuous variable, they observed that the likelihood of survival to discharge decreased 5.5% for every minute after EMS arrival (95% CI, 3.4-7.5; P < .001).
Moreover, among patients with a nonshockable cardiac rhythm, the RR for survival to hospital discharge was also highest in those who received epinephrine in the 0- and 5- minute window after EMS arrival (1.28; 95% CI, 0.95-1.72), but this finding was also not statistically significant.
When timing of epinephrine was assessed as a continuous variable, researchers observed that the likelihood of survival to discharge decreased approximately 4.4% for every minute after EMS arrival (95% CI, 0.8-7.9; P for interaction = .02).
Prehospital ROSC and functional outcomes
According to the study, the likelihood of favorable functional status at hospital discharge decreased as the timing of epinephrine increased for patients with either initially shockable (RR decrease per minute = 6.4%; 95% CI, 3.8-8.9; P for interaction < .001) or nonshockable rhythms (RR decrease per minute = 7.1%; 95% CI, 1.7-12.3; P for interaction = .01).
In contrast, the chances of prehospital ROSC increased as timing of epinephrine administration increased for patients with either initially shockable (RR decrease per minute = 1.4%; 95% CI, 0.2-2.7; P for interaction = .02) or nonshockable rhythms (RR decrease per minute = 1.5%; 95% CI, 0.6-2.4; P for interaction = .001).
“Findings of the present study support earlier epinephrine administration for OHCA with shockable and nonshockable cardiac rhythms and provide further evidence to complement these guidelines and recommendations,” the researchers wrote. “Another implication is that later epinephrine was found to be associated with ROSC but inversely associated with survival to hospital discharge and favorable functional outcomes. This discordance may suggest that later epinephrine administration might not be beneficial for survival to hospital discharge and functional recovery. The reasons for this discordance are unclear, but it is possible that longer resuscitation time may be associated with poor outcome, and epinephrine is the only intervention associated with increased odds of ROSC in patients with OHCA.”
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