Investigators may have uncovered the emergency medical service agency practices that result in favorable neurologic survival in patients who have experienced out-of-hospital cardiac arrests, according to a recent study published in JAMA Cardiology.

Emergency medical service agencies deploy paramedics to administer advanced life support, provide early emergency response, triage and transport patients, and offer community-based cardiopulmonary resuscitation (CPR) training. Although the agencies are often critical for prehospital treatment of out-of-hospital cardiac arrests, previous studies have found wide variations in the rate of cardiac arrest survival—ranging from 16.0% to 45.6% at the agency level. Favorable neurologic survival was defined as survival to hospital discharge with cerebral performance category scores of 1 or 2.

In the recent study, the investigators used patient-level data from the Cardiac Arrest Registry to Enhance Survival to analyze out-of-hospital cardiac arrest outcomes at 577 emergency medical service agencies—81.5% (n = 470) of which were included in the study—that treated 10 or more out-of-hospital cardiac arrests per year from January 2015 to December 2019. They noted that the registry currently has a catchment area that incorporates about 53% (n = 173 million) of the U.S. population.

The investigators used a multidisciplinary team of emergency medicine, internal medicine, and cardiology specialists; paramedics; epidemiologists; and qualitative researchers to develop an online survey covering 67 items across four domains: demographics and characteristics of the emergency medical service agencies, treatment of out-of-hospital cardiac arrests, non–emergency medical service agency stakeholder response to out-of-hospital cardiac arrests, and community factors affecting bystander response to out-of-hospital cardiac arrests. Each emergency medical service agency participating in the study was then asked to designate their most qualified individual to respond to the survey.

The investigators found that among the 181,707 patients treated for out-of-hospital cardiac arrests during the study period, the mean risk-standardized rate of favorable neurologic survival was 8.1% (range = 1.8%–14.8%) across the agencies. The mean rate of risk-standardized survival to hospital admission was 27.8% (range = 16.6%–43.4%). The investigators then categorized the emergency medical service agencies on the basis of their risk-standardized favorable neurologic survival rates. Patients treated at agencies in the highest quartile achieved a mean favorable neurologic survival rate of 12.0% (standard deviation [SD] = 1.3%) vs 6.0% (SD = 0.9%) among those treated at agencies in the lowest quartile.

The investigators found that seven practices—including certain methods of training, CPR, and transport—demonstrated higher rates of favorable neurologic survival at the agency level.

Among the practices were:

• Use of simulation to assess CPR competency
• Reassessment of CPR competency in new staff at least once every 6 months
• Utilization of full multiperson scenario simulation for ongoing skills training
• Performance of simulation training at least once every 6 months
• Training in the use of mechanical CPR devices at least once every 12 months
• Use of CPR feedback devices
• Transportation of patients to a designated cardiac arrest or ST-segment elevation myocardial infarction receiving center.

Compared with agencies belonging in the lowest quartile of favorable neurologic survival, emergency medical service agencies identified as belonging in the highest quartile of favorable neurologic survival were more likely to employ four or more of these practices (59.3% vs 35.6%).

The investigators hope their findings can illuminate the practices associated with the highest rate of favorable neurologic survival in this patient population. However, further studies may be needed to validate these initial insights and better outline best practices for treating out-of-hospital cardiac arrests in this setting.

A full list of disclosures can be found in the original study.