Measuring survival rates from sudden cardiac arrest: the elusive definition

Community-based automated external defibrillator only resuscitation for out-of-hospital cardiac arrest patients

BACKGROUND

Speed is the cornerstone of rescue for out-of-hospital cardiac arrest. As a consequence, community participation programs have been initiated to decrease response times. Even in the very best of these programs, however, short-term survival rates hover around 10% and long-term survival rates are half that. In most locales, survival is far worse. In Piacenza, Italy, responders have been trained for more than a decade to use publicly available automated external defibrillators (AEDs) and eschew the performance of cardiopulmonary resuscitation (CPR). It is known locally as "Progetto Vita."

METHODS

From 2001 to 2014, we prospectively collected outcome data on all Progetto Vita-treated patients and all 3271 standard emergency medical services (EMS) patients. Progetto Vita rescuers simply accessed a public AED, turned it on, and only followed its instructions. Progetto Vita rescuers did not do CPR of any sort. If EMS arrived prior to initiation or even completion of the Progetto Vita protocol, EMS-supplanted Progetto Vita efforts and patients were not included in the Progetto Vita cohort. Follow-up was collected by each responder's data files, medical record review, and use of the Italian system death index. All cardiac arrest patients' death status was validated in 100% of patients through August 1, 2014.

FINDINGS

Survival to hospital discharge occurred in 39 (41.4%) of the 95 patients treated by Progetto Vita and in 193 (5.9%) of the 3271 EMS patients. At 13-year follow-up, the Kaplan-Meier estimates of survival were 31.8% when AEDs only were used and 2.4% for standard EMS/CPR response. Estimates of survival are significantly better for Progetto Vita AED-only therapy when survival was stratified by time to respond, gender, location of cardiac arrest, and shockable rhythm. Relative to the 95 EMS patients with the fastest response times, Progetto Vita intervention was associated with a more than 2-fold increased rate of survival.

INTERPRETATION

This is the first demonstration of excellent long-term survival from out-of-hospital cardiac arrest by promoting speed and ease of lay AED response without CPR.

Derivation and initial application of a standard population for out-of-hospital cardiac arrest (SPOHCA)

AIM

While adjusting data for age, sex, race and/or socio-economic status is well established in out-of-hospital cardiac arrest (OHCA) research, there are shortcomings to reporting and comparing population-based OHCA outcomes. The purpose of this study was to derive a case-based standard population specific to EMS treated adult OHCA (SPOHCA) in the U.S., and demonstrate its application.

METHODS

The proposed SPOHCA was developed from three sources of multi-site OHCA data: the Cardiac Arrest Registry to Enhance Survival (CARES); the National EMS Information System (NEMSIS); and a published report from the Resuscitation Outcomes Consortium (ROC). OHCA data from a single EMS system were then used to demonstrate the application of SPOHCA. We report raw survival, population-based survival adjusted to the U.S. population, and the new SPOHCA-adjusted survival.

RESULTS

Observed raw survival was 12.3%. Adjustment to the demographic make-up of the adult U.S. population produced an adjusted incidence of 94.2 OHCA per 100,000 p-y, with a survival rate of 9.8 per 100,000 p-y. Using the proposed SPOHCA to adjust survival data produced an adjusted survival rate of 12.4%.

CONCLUSION

A case-based standard population provides for more practical interpretation of reported OHCA outcomes. We encourage a more widespread effort involving multiple stakeholders to further explore the effects of adjusting OHCA outcomes using the proposed SPOHCA instead of population-based demographics.

Cardiac arrest: a public health perspective

This article reviews out-of-hospital cardiac arrest from a public health perspective. Case definitions are discussed. Incidence, outcome, and fixed and modifiable risk factors for cardiac arrest are described. There is a large variation in survival between communities that is not explained by patient or community factors. Study of variation in outcome in other related conditions suggest that this is due to differences in organizational culture rather than processes of care. A public health approach to improving outcomes is recommended that includes ongoing monitoring and improvement of processes and outcome of care.

Variation in out-of-hospital cardiac arrest resuscitation and transport practices in the Resuscitation Outcomes Consortium: ROC Epistry-Cardiac Arrest

OBJECTIVES

To identify variation in patient, event, and scene characteristics of out-of-hospital cardiac arrest (OOHCA) patients assessed by emergency medical services (EMS), and to investigate variation in transport practices in relation to documented prehospital return of spontaneous circulation (ROSC) within eight regional clinical centers participating in the Resuscitation Outcomes Consortium (ROC) Epistry-Cardiac Arrest.

METHODS

OOHCA patient, event, and scene characteristics were compared to identify variation in treatment and transport practices across sites. Findings were adjusted for site and standard Utstein covariates. Using logistic regression, these covariates were modeled to identify factors related to the initiation of transport without documented prehospital ROSC as well as survival in these patients.

SETTING

Eight US and Canadian sites participating in the ROC Epistry-Cardiac Arrest.

POPULATION

Persons ≥ 20 years with OOHCA who (a) received compressions or shock by EMS providers and/or received bystander AED shock or (b) were pulseless but received no EMS compressions or shock between December 2005 and May 2007.

RESULTS

23,233 OOHCA cases were assessed by EMS in the defined period. Resuscitation (treatment) was initiated by EMS in 13,518 cases (58%, site range: 36-69%, p < 0.0001). Of treated cases, 59% were transported (site range: 49-88%, p < 0.0001). Transport was initiated in the absence of documented ROSC for 58% of transported cases (site range: 14-95%, p < 0.0001). Of these transported cases, 8% achieved ROSC before hospital arrival (site range: 5-21%, p < 0.0001) and 4% survived to hospital discharge (site range: 1-21%, p < 0.0001). In cases with transport from the scene initiated after documented ROSC, 28% survived to hospital discharge (site range: 18-44%, p < 0.0001).

CONCLUSION

Initiation of resuscitation and transport of OOHCA and the reporting of ROSC prior to transport markedly varies among ROC sites. This variation may help clarify reported differences in survival rates among sites and provide a target for identifying EMS practices most likely to enhance survival from OOHCA.

Essential features of designating out-of-hospital cardiac arrest as a reportable event: a scientific statement from the American Heart Association Emergency Cardiovascular Care Committee; Council on Cardiopulmonary, Perioperative, and Critical Care; Council on Cardiovascular Nursing; Council on Clinical Cardiology; and Quality of Care and Outcomes Research Interdisciplinary Working Group

The 2010 impact goal of the American Heart Association is to reduce death rates from heart disease and stroke by 25% and to lower the prevalence of the leading risk factors by the same proportion. Much of the burden of acute heart disease is initially experienced out of hospital and can be reduced by timely delivery of effective prehospital emergency care. Many patients with an acute myocardial infarction die from cardiac arrest before they reach the hospital. A small proportion of those with cardiac arrest who reach the hospital survive to discharge. Current health surveillance systems cannot determine the burden of acute cardiovascular illness in the prehospital setting nor make progress toward reducing that burden without improved surveillance mechanisms. Accordingly, the goals of this article provide a brief overview of strategies for managing out-of-hospital cardiac arrest. We review existing surveillance systems for monitoring progress in reducing the burden of out-of-hospital cardiac arrest in the United States and make recommendations for filling significant gaps in these systems, including the following: 1. Out-of-hospital cardiac arrests and their outcomes through hospital discharge should be classified as reportable events as part of a heart disease and stroke surveillance system. 2. Data collected on patients' encounters with emergency medical services systems should include descriptions of the performance of cardiopulmonary resuscitation by bystanders and defibrillation by lay responders. 3. National annual reports on key indicators of progress in managing acute cardiovascular events in the out-of-hospital setting should be developed and made publicly available. Potential barriers to action on cardiac arrest include concerns about privacy, methodological challenges, and costs associated with designating cardiac arrest as a reportable event.

Lay rescuer automated external defibrillator ("public access defibrillation") programs: lessons learned from an international multicenter trial: advisory statement from the American Heart Association Emergency Cardiovascular Committee; the Council on Cardiopulmonary, Perioperative, and Critical Care; and the Council on Clinical Cardiology

Lay rescuer automated external defibrillator (AED) programs may increase the number of people experiencing sudden cardiac arrest who receive bystander cardiopulmonary resuscitation (CPR), can reduce time to defibrillation, and may improve survival from sudden cardiac arrest. These programs require an organized and practiced response, with rescuers trained and equipped to recognize emergencies, activate the emergency medical services system, provide CPR, and provide defibrillation. To determine the effect of public access defibrillation (PAD) programs on survival and other outcomes after SCA, the National Heart, Lung, and Blood Institute, the American Heart Association (AHA), and others funded a large prospective randomized trial. The results of this study were recently published in The New England Journal of Medicine and support current AHA recommendations for lay rescuer AED programs and emphasis on planning, training, and practice of CPR and use of AEDs. The purpose of this statement is to highlight important findings of the Public Access Defibrillation Trial and summarize implications of these findings for healthcare providers, healthcare policy advocates, and the AHA training network.

Delaying shock for cardiopulmonary resuscitation: does it save lives?

PURPOSE OF REVIEW

Out-of-hospital cardiac arrest claims more than 450,000 lives annually in North America. Many communities have dedicated significant resources to provide rapid defibrillator response for patients in ventricular fibrillation. In spite of these efforts, mortality from out-of-hospital cardiac arrest has not improved significantly. Emerging evidence suggests some patients in ventricular fibrillation arrest may be harmed by immediate defibrillation.

RECENT FINDINGS

Recent laboratory studies have shown benefit in performing a period of chest compressions (cardiopulmonary resuscitation) prior to defibrillation in models with more than 4 minutes of induced ventricular fibrillation. During the initial 4 minutes the heart is more amenable to electrical defibrillation. Between 4-10 minutes, chest compressions create some coronary perfusion and fill the left ventricle to prepare the heart for electric shock. These findings, in conjunction with most emergency medical service response times reported to be 5-8 minutes, have prompted human investigation into a strategy of chest compression first. A recent randomized controlled trial reported a fivefold increase in survival for patients with more than 5 minutes of VF who received 3 minutes of chest compressions prior to defibrillation compared with those who had not.

SUMMARY

Current guidelines call for rapid defibrillation as the most important 'link' in the 'chain of survival'. For most ventricular fibrillation patients who have professional rescuers arrive after 5-8 minutes of ventricular fibrillation, however, immediate defibrillation is likely to be ineffective. Counterintuitively, these patients may benefit from a period of chest compressions prior to being shocked.

Public-access defibrillation and survival after out-of-hospital cardiac arrest

BACKGROUND

The rate of survival after out-of-hospital cardiac arrest is low. It is not known whether this rate will increase if laypersons are trained to attempt defibrillation with the use of automated external defibrillators (AEDs).

METHODS

We conducted a prospective, community-based, multicenter clinical trial in which we randomly assigned community units (e.g., shopping malls and apartment complexes) to a structured and monitored emergency-response system involving lay volunteers trained in cardiopulmonary resuscitation (CPR) alone or in CPR and the use of AEDs. The primary outcome was survival to hospital discharge.

RESULTS

More than 19,000 volunteer responders from 993 community units in 24 North American regions participated. The two study groups had similar unit and volunteer characteristics. Patients with treated out-of-hospital cardiac arrest in the two groups were similar in age (mean, 69.8 years), proportion of men (67 percent), rate of cardiac arrest in a public location (70 percent), and rate of witnessed cardiac arrest (72 percent). No inappropriate shocks were delivered. There were more survivors to hospital discharge in the units assigned to have volunteers trained in CPR plus the use of AEDs (30 survivors among 128 arrests) than there were in the units assigned to have volunteers trained only in CPR (15 among 107; P=0.03; relative risk, 2.0; 95 percent confidence interval, 1.07 to 3.77); there were only 2 survivors in residential complexes. Functional status at hospital discharge did not differ between the two groups.

CONCLUSIONS

Training and equipping volunteers to attempt early defibrillation within a structured response system can increase the number of survivors to hospital discharge after out-of-hospital cardiac arrest in public locations. Trained laypersons can use AEDs safely and effectively.