Temporal Changes in Epinephrine Dosing in Out-of-Hospital Cardiac Arrest: A Review of EMS Protocols across the United States

Background: Administration of epinephrine has been associated with worse neurological outcomes for survivors of out-of-hospital cardiac arrest. The publication of the 2018 PARAMEDIC-2 trial, a randomized and double-blind study of epinephrine in out-of-hospital cardiac arrest, provides the strongest evidence to date that epinephrine increases return of spontaneous circulation (ROSC) but not neurologically intact survival. This study aims to determine if Emergency Medical Services (EMS) cardiac arrest protocols have changed since the publication of PARAMEDIC-2. Methods: States in the US utilizing mandatory or model state-wide EMS protocols, including Washington DC, were included in this study. The nontraumatic cardiac arrest protocol as of January 1, 2018 was compared to the protocol in effect on January 1, 2021 to determine if there was a change in the administration of epinephrine. Protocols were downloaded from the relevant state EMS website. If a protocol could not be obtained, the state medical director was contacted. Results: A 2021 state-wide protocol was found for 32/51 (62.7%) states. Data from 2018 were available for 21/51 (41.2%) states. Of the 11 states without data from 2018, all follow Advanced Cardiac Life Support (ACLS) guidelines in the 2021 protocol. Five (15.6%) of the states with a state-wide protocol made a change in the cardiac arrest protocols. Maximum cumulative epinephrine dose was limited to 4mg in Maryland and 3mg in Vermont. Rhode Island changed epinephrine in shockable rhythms to be administered after three cycles of cardiopulmonary resuscitation (CPR) and an anti-arrhythmic. Rhode Island also added an epinephrine infusion as an option. No states removed epinephrine administration from their cardiac arrest protocol. Simple statistical analysis was performed with Microsoft Excel. Conclusion: Several states have adjusted cardiac arrest protocols since 2018. The most frequent change was limiting the maximum cumulative dosage of epinephrine. One state changed timing of epinephrine dosing depending on the rhythm and also provided an option of an epinephrine infusion in place of bolus dosing. While the sample size is small, these changes may reflect the future direction of prehospital cardiac arrest protocols. Significant limitations apply, including the exclusion of local and regional protocols which are more capable of quickly adjusting to new research. Additionally, this study is only focused on EMS in the United States.