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CHAPTER 12 Cardiac arrest systems of care
Bryan McNally, Paul M. Middleton, Marcus E.H. Ong, and Gayathri Devi Nadarajan
Introduction
The original motivations to develop emergency medical services (EMS) systems were to improve the care of patients suffering from major trauma and out‐of‐hospital cardiac arrest (OHCA). Physicians and resuscitation researchers often focus on patient‐level perspectives of cardiac arrest care (e.g., specific drugs or treatment algorithms). However, the most important factors determining OHCA survival involve the systems of community care.
Recognition that OHCA survival depended on the time intervals from collapse to initiation of CPR and to defibrillation spurred extensive EMS and public safety efforts to achieve faster response and earlier defibrillation. These efforts included the use of firefighters and police officers as first‐responders, training emergency medical technicians (EMTs) to perform defibrillation, and strategic deployment of advanced life support units (systems status management). However, there were, and remain, inherent logistical limits to first‐responder speed.
Development of the automated external defibrillator (AED) led to the concept of public‐access defibrillation (PAD) [1]. The AED emphasized the potential of immediate bystander action in the management of cardiac arrest. Every EMS medical director, manager, and clinician must recognize the importance of this principle. EMS personnel and hospital staff have less influence on OHCA survival than do bystander CPR and AED use (Figure 12.1) [2]. OHCA survival when there is bystander CPR and an AED is used may be as high as 33‐50% [3–5]. State‐level data from the Cardiac Arrest Registry to Enhance Survival (CARES) program (https://mycares.net), including OHCA incidence and survival rates, demonstrate the effect of bystander interventions early in the “chain of survival” (Table 12.1) [6].
Optimal OHCA survival depends on a comprehensive community‐based approach that includes collecting essential OHCA outcome data as part of a continuous quality improvement program to improve care. Programs like CARES and the Pan Asian Resuscitation Outcomes Study (http://www.scri.edu.sg/index.php/networks‐paros) provide communities with the necessary tools to collect OHCA data in an ongoing efficient manner, enabling benchmarking and gauging effectiveness in a real‐world environment [4,7–8]. In King County, Washington, the Resuscitation Academy (http://www.resuscitationacademy.com) was created to help communities develop local quality assurance programs through a 3‐day fellowship program designed specifically for EMS clinicians, administrators, and medical directors.
Implementation of a community systems‐based approach is as important a role for EMS agencies as the direct patient care they deliver. This chapter provides an overview of the system‐level considerations in cardiac arrest resuscitation and care.
Epidemiology of Cardiac Arrest
The annual incidence of OHCA in the United States is estimated between 166,000 and 450,000 cases [59–10]. The reported incidence varies with the source of the data and definitions used. Precise epidemiological information is limited because the Centers for Disease Control and Prevention does not consider OHCA a reportable disease [11]. The rate of OHCA disability adjusted life years is 1347 per 100,000 population, which ranks third in the United States behind ischemic heart disease and low back and neck pain [12].
Many cardiac arrests are due to ventricular fibrillation (VF) or ventricular tachycardia (VT), but the proportion remaining in shockable rhythms on EMS arrival varies with the time from collapse to initial assessment. Studies based on patients who are hospitalized report shockable rhythms in about 75% of cases, whereas EMS studies report figures ranging from 24% to 60% [413–18]. EMS data suggest that the rate of out‐of‐hospital VF/VT may be decreasing, but the overall incidence of OHCA is not [19–22]. However, studies with rhythms recorded by on‐site defibrillators continue to identify VF/VT as the most common initial rhythm. VF/VT was the presenting rhythm in 61% of arrests in the casino trial and 59% of the patients in the PAD trial [23, 24].
Figure 12.1 Contributors to cardiac arrest survival. While the first links of cardiac arrest care (early 9‐1‐1, early bystander CPR, and early defibrillation) contribute to cardiac arrest survival, ALS care does not.
Source: Stiell IG, Wells GA, Field B, et al. Advanced cardiac life support in out‐of‐hospital cardiac arrest. N Engl J Med. 2004; 351:647–56. © 2004 Massachusetts Medical Society. All rights reserved.
The average survival to hospital discharge after OHCA is estimated to be between 5% and 10%, but reported OHCA survival rates also vary widely [4,25–29]. There are likely several reasons for this, including differing denominators, varying definitions of survival, and possibly true regional differences [24]. In CARES, which comprises more than 1,800 EMS agencies covering a catchment area of nearly 152 million people, an eight‐fold difference in survival (2.5–21.1%) was found between sites with at least 150 cardiac arrests annually. Cases witnessed by bystanders and presenting with shockable rhythms also had an eight‐fold difference in survival (7.7–64%), and rates of bystander CPR had a five‐fold difference (14.6–77.8%) [6].
Elements of a Community Cardiac Arrest Care System
The key elements of a community cardiac arrest care system were initially described in the “chain of survival.” However, for this to be effective, there need to be other supporting pre‐requisites within the system. This can be depicted in the “frame of survival”, which has the chain of survival at its core, encapsulated by the prerequisites (Figure 12.2). The inner frame depicts pre‐requisites that are within the control of local EMS, while the outer frame are those subjected to governmental bodies. The EMS medical director has an important role as the bridge between the inner and outer frames.
Such a framework