Resident Eagle: Epinephrine in OHCA

Resident Eagle is a monthly column profiling the work of top EMS physicians and medical directors from the Metropolitan EMS Medical Directors Global Alliance (the "Eagles"), who represent America’s largest and key international cities. 

Tentative dates for Gathering of Eagles 2021: June 14–18, Hollywood, Fla. For more see useagles.org.

Authors’ note: The opinions within this article are those of the El Paso County, Colo. EMS Medical Director Committee and are not to be considered the consensus of the Eagles Consortium. However, the propositions stated exemplify the progressive nature and philosophy of the Eagles Consortium as a group that strives to seek out and drive best practices for early resuscitative interventions for cardiac care and other critical medical and traumatic emergencies in the prehospital setting.

In March 2020, as reports began to surface from urban centers across the country of COVID-19’s impacts on the EMS community—including high exposure and quarantine rates—EMS leaders began to consider options to prepare for the ensuing pandemic. Thresholds for pandemic adaptations varied widely based on the idiosyncrasies of individual communities. Changes in response, PPE, treatment, and transport guidelines were adopted, at least in part with the objective to create a new balance between limiting EMS personnel exposure while still maintaining a high standard of medical care for patients. 

With out of hospital cardiac arrest (OHCA) and death rates increasing dramatically in some regions, there was also the need for scrutiny of resuscitation protocols. Since OHCA care is a very intimate, prolonged-exposure experience with presumed high COVID transmission risk for EMS personnel, consideration of where we could quickly decrease provider exposure risk began with a careful look at the evidence-based medical treatments and interventions rendered in OHCA.

We decided to reevaluate all close-contact interventions not backed by evidence-based outcome data. Among adaptations to our resuscitation protocols, such as airway management and decreasing the number of participating providers, we  scrutinized our pharmacology. We determined justifying use of epinephrine in OHCA must be viewed through a different lens in the setting of the COVID-19 pandemic and deliberated the longstanding question of efficacy of epinephrine in OHCA management. 

Background of Epinephrine for OHCA

Although it is well established that the quality of chest compressions, uninterrupted continuous compressions, and early defibrillation in v-fib/v-tach arrests improve the ability to achieve ROSC and lead to neurologically intact discharge from the hospital in patients suffering from cardiac arrest, other OHCA interventions we routinely perform, such as administration of vasopressors and advanced airways, are not backed up by strong evidence.

Epinephrine is ubiquitously administered in cardiac arrests. Its alpha 1-mediated vasoconstriction is what benefits cardiac arrest patients by driving up the coronary perfusion pressure. However, epinephrine’s chronotropy and inotropy properties can also increase the myocardial oxygen demand and lead to ventricular arrhythmias. Epinephrine can also lead to hypokalemia, and its vasoconstrictive effects on microcirculation can lead to occlusion and end-organ ischemia. 

For over a decade there has been a plethora of literature challenging the efficacy of epinephrine in cardiac arrest (see table). The overarching conclusions of these studies are that even though the use of epinephrine in OHCA increased ROSC and survival to hospital admission, it did not increase the rate of survival to hospital discharge, and epinephrine worsened neurological outcome for many who did survive to hospital discharge. 

Even faced with an abundance of evidence showing no benefit from Epinephrine in OHCA, the resistance to give up epinephrine in cardiac arrest management seems to anecdotally boil down to feelings of “If I don’t give it, I’m not doing everything I can,” or “But what is the harm” or “We achieve the win of ROSC!”  

Effect of the COVID Pandemic

With no meaningful evidence-based improvement in the important ultimate outcomes obtained from epinephrine, COVID-19 seemed to present us with a very different risk/benefit equation. For the first time there was a theoretical possibility of harm tied to the use of epinephrine for OHCA, along with any other intervention that required close patient contact, which increased potential transmission of COVID to first responders. Our collective decision was to remove epinephrine altogether from EMS OHCA protocols in El Paso County (population 740,000).

As we gained additional knowledge, the El Paso County EMS Medical Director Committee reevaluated the changes we originally made to our OHCA protocols. We decided to refrain from reimplementation of epinephrine, no longer because of provider exposure fear but rather because there was no reason to reengage in an intervention that has so much evidence against its ability to increase neurologically meaningful survival.

EMS has long measured its OHCA resuscitation “success” on ROSC and survival to the hospital. This is an antiquated thought process, gauging success only while a patient is in the hands of EMS. As the EMS world fully engages as a partner in the healthcare continuum, we must expand our definition of success toward the goal of collectively achieving the most successful outcomes, which should be measured by neurologically meaningful survival to hospital discharge and beyond. Stepwise successes during and after resuscitation should only be meaningful if an isolated intervention affords a patient a bridging opportunity to receive subsequent interventions that lead to the possibility of a truly successful outcome. The use of epi in OHCA has not been shown to provide this.

No Negative Outcomes

Our overall ROSC rate in OHCA has dropped during the pandemic; however, we have also experienced an overall increase in nonshockable rhythms. Our initial data on ROSC seems to preliminarily fall in line with other regions experiencing decreased ROSC rates. Based on this we are preliminarily surmising that our omission of epinephrine in all OHCA resuscitations has not resulted in overall negative patient outcomes. We have seen an increase in the absolute number of patients with survival to discharge from the hospital with intact neurologic function. We will continue to track our arrest data specifically trying to isolate out impacts of removal of epinephrine and look forward to sharing our experience and data in the future. 

Matthew Angelidis, MD, is an ER physician at UCHealth and medical director for UCHealth EMS, as well as co-medical director for the Colorado Springs Fire Department and Colorado Springs AMR. 

E. Stein Bronsky, MD, is co-medical director for the Colorado Springs Fire Department and Colorado Springs and El Paso County AMR in Colorado, as well as medical director for the El Paso–Teller County 9-1-1 Authority. He is an emergency medicine physician with Centura Health/U.S. Acute Care Solutions.