Dispatcher-assisted CPR and Impact on Survival Rates
Source: Rea TD, et al. Dispatcher-assisted cardiopulmonary resuscitation and survival in cardiac arrest. Circulation 2001; 104:2513-1256.
Approximately 250,000 people suffer out-of-hospital cardiac arrest each year in the United States; of those, one-third receive bystander cardiopulmonary resuscitation (CPR), and 5% survive to hospital discharge. Previous studies have demonstrated that real-time 911 dispatcher assistance and guidance with CPR increases the proportion of cardiac arrest victims who receive lay public bystander CPR. However, there has been little data on whether such dispatcher-assisted CPR in the field has any measurable outcome benefit.
This retrospective cohort analysis studied the impact of a dispatcher-assisted CPR program on the rate of hospital survival-to-discharge among victims of cardiac arrest in the field setting. The investigators analyzed emergency medical services (EMS) and hospital records for 7945 persons who experienced a field arrest due to cardiac causes during a 17-year period (1983-2000) in Kings County, WA. Three cohorts were defined: patients who did not receive bystander CPR (no CPR, 44%); those who received bystander CPR without dispatcher assistance (unassisted CPR, 30%); and those who received bystander CPR with dispatcher assistance (assisted CPR, 26%).
The overall survival-to-discharge rate was 15%. Survival rates were greater for the unassisted CPR and assisted CPR groups (27% and 18%, respectively) vs. the no CPR group (13%). Multivariate odds ratio for survival were significantly higher in the unassisted CPR (1.69) and assisted CPR (1.45) groups when adjusted for age, sex, location, whether the arrest was witnessed, and EMS response time. In addition, there was no change in the results if researchers excluded cases in which bystander CPR was performed by medical professionals.
When analyzing the subgroup of witnessed arrests, the investigators found that the time to any CPR efforts (by bystander, EMS, or other personnel) were markedly shorter in the unassisted and assisted groups. However, the initiation of CPR with dispatcher assistance took approximately one minute longer than when initiated by bystanders who did not need assistance. Interestingly, while overall there was improved survival with unassisted CPR vs. assisted CPR, there was no difference in the subgroup of patients with prolonged EMS response times (> 5 minutes), suggesting that beyond the one-minute delay, the quality of CPR was comparable.
The authors conclude that dispatcher-assisted CPR led to greater numbers of patients receiving bystander CPR, shorter time to the initiation of CPR efforts, and improved survival for patients who suffer cardiac arrest in the field.
Commentary by Theodore C. Chan, MD, FACEP
This large cohort study again confirms that early CPR saves lives. More specifically, this study demonstrates that 911 dispatchers by telephone can assist and direct bystanders to initiate CPR on cardiac arrest victims, resulting in more patients receiving bystander CPR earlier and improving their chances for survival.
It should be noted that only survival-to-hospital-discharge was studied; no assessment of the patients’ neurologic status and quality of life was made. Moreover, as a retrospective study, there may have been underlying biases as to who received and did not receive dispatcher assistance. Most importantly, this study was conducted in a community well-known for its outstanding public CPR training and outreach programs, as well as for tremendous arrest survival rates that have been difficult to replicate in other communities. Similarly, the success of dispatcher-assisted programs may not be easy to reproduce in other urban settings.
Despite these limitations, the findings of this study are impressive given the approximately 50% improvement in survival with dispatch-assisted CPR. Moreover, dispatch instruction in this study included ventilation and chest compression. The most recent American Heart Association guidelines recommend limiting such instructions to chest compression only, as research suggests equal efficacy.1 Given this simplification, the potential impact of dispatch-assistance programs may even be greater in the future.
Most patients in the no CPR and assisted CPR groups suffered their arrests at private homes (81% and 94%, respectively), as opposed to the unassisted CPR group (38%). As the large majority of cardiac arrests take place at home, this finding further emphasizes the real and potential benefit of dispatcher-assisted CPR. Programs such as these, as well as other efforts expanding public access defibrillation and citizen CPR training, hopefully will make inroads into the overall dismal rate of cardiac arrest survival.
Reference
1. Kern KB, et al. New guidelines for cardiopulmonary resuscitation and emergency cardiac care: changes in the management of cardiac arrest. JAMA 2001;285: 1267-1269.
Dr. Chan, Associate Clinical Professor of Medicine, Emergency Medicine, University of California, San Diego, is on the Editorial Board of Emergency Medicine Alert.
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