The Effect of Bystander CPR on Survival of Out-of-Hospital Cardiac Arrest Victims

Ritter G, Worlfe RA, Goldstein S, Landis JR, Vasu CM, Acheson A, Leighton R, Vanderbrug Medensrop S American Heart Journal 1985 Vol 110 Pages 932-937

The effect of bystander CPR was studied in 2,142 Emergency Medical Service cardiac arrest runs in Lucas County, Ohio, and in Kent County, and Southfield, Michigan, that occurred between September 1977 and July 1982. At the time, Southfield was a suburban community with a population density of 2,700 persons per square mile, while Lucas and Kent Counties had population densities of 1,400 and 500 respectively. In 305 out of 2,142 instances, cardiac arrest occurred after EMS arrived and emergency care which included intubation and defibrillation was immediately instituted. These patients received optimal emergency care in the field and are the standard for measurement of the effect of CPR and EMS response time. When bystander CPR was administered to cardiac arrest victims (472 patients or 22% of the cardiac arrests), 22.9% of the victims survived until they were admitted to hospital and 11.9% were discharged alive. In comparison, stats for cardiac arrest victims who did not receive bystander CPR were 14.6% and 4.7% respectively (P<0.001). A critical factor in patient survival was the amount of time that elapsed before EMS personnel arrived and administered CPR. Patients who received bystander CPR were more likely to have ventricular fibrillation when EMS arrived. Other factors relating to patient survival were the location of the victim at the time of the cardiac arrest and the age of the victim. Victims who suffered cardiac arrest at work were more likely to receive bystander CPR (62.7%) and be discharged from hospital alive (21.7%) than victims who arrested at home (18.2% and 6.4% respectively). Patients who experienced cardiac arrest in a public place had intermediate percentages. The average EMS response time was shortest (4.1 minutes) for patients at work, about .5 minutes longer (4.7 minutes) for public places, and longest (5.5 minutes) for patients at home (P<0.0001). Ventricular fibrillation was the most common rhythm at arrival. Asystolic patients were less likely to survive until discharge from the hospital than were patients with other initial rhythms (P<0.01). The initial cardiac rhythm in 73% of the patients who received bystander CPR was ventricular fibrillation or tachycardia as compared to 64% of patients who did not receive bystander CPR (P<0.01). The model developed from this study, predicts that survival for typical patients who receive CPR is 13% with a 1 minute response time and 8% with a 4-5 minutes response time. The model also shows that the survival rate for a typical patient arresting at work would be 17.5%, vs. 7% at home. The model shows that the effect of bystander CPR on patient survival to discharge from hospital is equivalent to the effect of a 4 minute earlier EMS response time. Therefore, CPR is a substantial and significant predictor of survival above and beyond any differences between patients who receive or do not receive CPR with respect to response time, age, etc. Understanding these factors is important in developing community strategies to treat patients with cardiac arrest out of hospital. The study provides further support for the benefit of bystander CPR coupled with EMS and provides a direction to achieve maximum benefit from both of these programs.