Strategies for Enhancing Prehospital Outcomes for Cardiac Arrest (EPOC)

Out-of-hospital cardiac arrest (OHCA) is a common, life-threatening event that is a leading cause of death in the United States. Of the approximately 305,800 cases of OHCA treated by emergency medical services (EMS) in 2021, about 91 percent result in death (Cardiac Arrest Registry to Enhance Survival, 2021). An estimated 24 percent of patients survive to hospital admission, and 9 percent are discharged alive (Cardiac Arrest Registry to Enhance Survival, 2021). A 2015 National Academy of Medicine report highlighted substantial regional variations in successful OHCA response and treatment across the United States—specifically, survival rates between communities (Graham, McCoy, and Schultz, 2015).

To improve patient outcomes, it is imperative to understand how EMS agencies treat OHCA in routine clinical practice. The American Heart Association (AHA) recognizes the chain of survival as an operational framework for assessing EMS response to OHCA. This framework consists of six interdependent links:

• recognition of cardiac arrest and activation of emergency response
• early cardiopulmonary resuscitation (CPR)
• rapid defibrillation
• effective advanced cardiac life support (ACLS)
• integrated post-resuscitative care
• recovery (Merchant et al., 2020).

Each link in the chain of survival must be considered when evaluating opportunities for improving EMS care quality for OHCA. When these links are implemented, victims have improved chances of survival. For example, among nontraumatic cardiac arrests witnessed by bystanders and found in a shockable rhythm in 2021, survival was actually 29 percent (Cardiac Arrest Registry to Enhance Survival, 2021).

However, it is unclear how to design strategies that best address these links and can be successfully implemented in EMS agencies and broader emergency response systems (such as fire, police, dispatch, and bystanders to OHCA events) in different communities to help improve daily care processes and outcomes in OHCA. Accordingly, the National Heart, Lung, and Blood Institute (NHLBI)–funded Enhancing Pre-Hospital Outcomes for Cardiac Arrest (EPOC) study lays the foundation for future quality improvement efforts in OHCA by identifying, understanding, and validating the strategies adopted within emergency response systems to address these life-threatening events and by addressing potential barriers to implementation of these practices. These approaches, taken together, form the EPOC strategies described in the study.

Focus of the Study

The findings from the EPOC study were analyzed to produce strategies to improve OHCA survival and care delivery in communities across the United States. The two aims of the EPOC study leading to the strategies were:

• Aim 1. Identify variations in OHCA survival among EMS agencies and communities.
• Aim 2. Define system-of-care best practices for OHCA survival.

The study focused on prehospital care in Michigan, particularly those EMS agencies that participated in the Michigan Cardiac Arrest Registry to Enhance Survival (MI-CARES) (Abir et al., 2021). We focused on care in the prehospital setting because this area of care has been shown to vary strongly across communities, and little is known about the impact of different processes of care for OHCA despite its importance.

Methods

This study used a mixed-methods approach. First, a quantitative analysis was performed to stratify high-, intermediate-, and low-performing emergency response systems. Second, we conducted in-depth, semistructured key informant interviews and multidisciplinary focus groups with more than 160 personnel from 911/dispatch, EMS, non-transport fire, and police in nine emergency response systems with high-, intermediate-, and low-survival outcomes to produce and validate our findings. Information from these site visits was then compiled and analyzed using qualitative analysis. Strategies identified from the qualitative analysis were extracted by two researchers into templates organized by different categories relating to the OHCA system of care to inform our strategies. Third, we conducted a literature review of peer-reviewed publications to determine how our findings might be enhanced and refined by the current academic knowledge on the varied issues across the system of care for OHCA. Approaches were deemed applicable for our strategies according to the level of supporting evidence from all of the qualitative and literature review data.

One of the approaches we used to identify best practices was to compare the high-performing emergency medical systems that we visited with the low-performing ones. We started with site visits to high-performing sites and to low-performing sites. Upon completing these site visits, we looked across the interview and focus group transcripts to see what high-performing systems did (and, conversely, low-performing systems did not do). These comparisons helped identify promising OHCA response strategies, especially those that were noted as important for success in high-performing sites and were absent in low-performing sites. Promising practices were also identified in low-performing sites, particularly where they address important barriers to high performance, and some informed the recommended strategies in this report. The two intermediate performing systems were in rural areas with some creative solutions to OHCA response in the setting of poor resources.

Results and Strategies

Findings from the analysis revealed strategies to improve OHCA survival and potential practices to improve care delivery from a system-of-care perspective. We developed a total of 49 strategies covering all levels of the prehospital OHCA incident response and the principles of change management necessary to implement the strategies. These are listed in Table 1. These strategies cover the incident, stakeholder, and system levels. Strategies to improve OHCA outcomes can be adopted by individual stakeholders but are also applicable across the system of care.