Journal Watch: Best Practices in Cardiac Arrest

Reviewed This Month

Rationale and Strategies for Development of an Optimal Bundle of Management for Cardiac Arrest

Authors: Pepe PE, Aufderheide TP, Lamhaut L, et al.     

Published in: Crit Care Explor, 2020 Oct 15; 2(10): e0214. 

Previous Journal Watch columns have noted that randomized controlled clinical trials (RCTs) are the gold standard for evaluating the effectiveness of interventions. However, it takes a lot of upfront work to run a high-quality RCT. From careful selection of the population and setting to the logistics of blinding participants and investigators, there are an almost endless number of things to complete before even one patient is enrolled. 

When everything (almost!) goes right, the study can tell us something about the cause-and-effect relationship between an intervention and an outcome. Multiple well-done RCTs may prove causality. However, the authors of the study we review this month correctly point out that failure to control for important factors in a study design, such as CPR performance, could lead to conflicting results. They further note variations in EMS system configurations make the study of a single prehospital intervention exceedingly difficult. One intervention may work well in one EMS system but be ineffective in another. 

Instead of seeking to identify one “silver bullet” for treatment of cardiac arrest, the authors of this month’s study sought to examine “well-choreographed, multifaceted, interdependent bundles of treatment” with the goal of developing “a highly detailed yet practical, attainable roadmap for enhancing the likelihood of neurologically intact survival” following OHCA events. 

This study included both qualitative and quantitative evaluations. First they identified 10 EMS systems from across the U.S. that recently reported “significant improvements in neurologically intact survival after introducing a more comprehensive approach involving citizens, hospitals, and evolving strategies for incorporating technology-based, highly choreographed care and training.” But the authors did not exclusively rely on the original study results that showed the improvements in those 10 systems—those studies only compared each system’s performance to its past performance, and there are known limitations to using historical controls. Rather, they completed their own separate analysis that compared the mean rate of hospital discharge with favorable neurologic outcome among the 10 EMS systems to data obtained from the Cardiac Arrest Registry to Enhance Survival (CARES). In this analysis they found mean rates of hospital discharge with favorable neurologic outcome among these 10 EMS systems were significantly higher than the CARES comparison group. 

A total of 2,911 OHCA patients were treated by the 10 systems (EMS-10) during the analysis period. Their mean rate of hospital discharge with a favorable neurologic outcome was 10.7% vs. 8.4% in CARES (p<0.002; OR=1.30, 95% CI: 1.159–1.473). 

Common Elements

The authors then identified “readily acceptable” common elements and best practices among each of the EMS-10. To identify commonalities among these high-performing systems, the International Resuscitation Collaborative (IRC) met to review, analyze, and collate their inventories. The IRC is a well-regarded group of cardiologists, emergency and internal medicine physicians, paramedics, and fire-rescue leaders in the U.S., Canada, and Europe that consists largely of those who have published or reported new approaches to CPR with associated high rates of resuscitation and neurologically intact survival for both OHCA and in-hospital cardiac arrest. 

At the IRC meetings each system delivered a podium-style presentation, followed by focus group roundtables. Strategies, interventions, protocols, and procedural approaches were tabulated to identify commonalities, differences, and complementary elements. IRC members distilled the information gathered at these meetings to create a recommended bundle of care. 

The bundle of care included four categories: community response, first responder/basic life support, advanced life support, and in-hospital care. There were common elements shared by all 10 EMS systems in each of these categories. Common elements in the community response category included dispatch-assisted CPR, public AEDs, public training efforts, and governmental support and involvement. Common elements shared by EMS-10 in the first responder/BLS category included immediate chest compressions, two-hand facemasks/supraglottic airway capabilities, impedance threshold devices, and automated external defibrillators. Advanced life support common elements included mechanical CPR, IV/IO, intubation, EtCO₂ monitoring, and termination protocols. The in-hospital category included cardiac catheterization labs and percutaneous coronary intervention, therapeutic temperature management to 33ºC, cardiac surgery, and multispecialty practice. 

Pillars of Care

In addition to the bundles of care, the IRC identified seven “pillars” of care to be considered when implementing a comprehensive resuscitation bundle. These include:

• Enhanced first response by less-experienced rescuers (e.g., community response or citizen activation) so early CPR and defibrillation are provided on a consistent basis; 
• Consistent performance of high-quality manual CPR by designated professional rescuers;
• Enhanced hemodynamics during CPR using technologies to significantly augment cerebral and coronary blood flow and help lower intracranial pressure compared to traditional manual CPR;
• Technologies that improve defibrillation success in patients with ventricular fibrillation or pulseless ventricular tachycardia; 
• Strategies to reduce reperfusion injury, either following ROSC or from the performance of CPR itself; 
• Use of noninvasive monitoring of circulation (e.g., EtCO₂), neuromonitoring, and neuroprognostication to help guide, optimize, and individualize CPR and post-arrest care; and 
• Focus on arrest prevention for both OHCA and in-hospital cardiac arrest, including the use of predictive analytics to enhance triage and allow anticipation, rapid identification, and reversal of impending deterioration for at-risk patients. 

The authors concluded that the “likelihood of neurologically favorable survival following out-of-hospital cardiac arrest can improve substantially in communities that conscientiously and meticulously introduce a well-sequenced, highly choreographed, systemwide portfolio of both traditional and nonconventional approaches to training, technologies, and physiologic management.”

Limitations

Every study has limitations, this one included. A more comprehensive explanation of the IRC member selection process certainly would help for anyone seeking to replicate this study. It is possible a different group of subject matter experts may have identified other important bundles. However, this was a very interesting study, and I hope you will read the full manuscript. It includes other bundles identified that were common but not shared by all 10 EMS systems.  

Antonio R. Fernandez, PhD, NRP, FAHA, is a research scientist at ESO and serves on the board of advisors of the Prehospital Care Research Forum at UCLA.