NIH study suggests out-of-hospital cardiac arrest survival rates can double with trained lay-person intervention

By Michael Ford
University News Services

RICHMOND, Va. (Aug. 11, 2004) – The number of people who survive heart attacks in public places could double if lay volunteers are trained to use public access defibrillators, according to a study published today in the New England Journal of Medicine.

The study, conducted between July 2000 and September 2003, was funded by a grant from the National Heart, Lung, and Blood Institute, of the National Institutes of Health, in collaboration with the American Heart Association. Virginia Commonwealth University researcher, Joseph P. Ornato, M.D., was chair of the steering committee that conducted the multi-center study among 24 regions in North America.

Sudden, out-of-hospital, cardiac arrest is a leading cause of death and disability in the United States and is a leading source of health care costs, according to the AHA. Nearly a quarter of the 400,000 to 460,000 deaths from cardiac arrest each year occur outside the home in public places.

“When out-of-hospital cardiac arrest is caused by ventricular fibrillation -- that is when the heart’s electrical activity falls out of rhythm -- defibrillation is an effective treatment when delivered in a timely manner,” said Ornato, chairman of emergency medicine at the VCU Medical Center. “The problem is time.

“The chances of survival for victims of cardiac arrest diminish by 10 percent as each minute passes,” he said. “Getting help quickly can make the difference between life and death.”

Today, in most cities, fewer than 5 percent of people who suffer cardiac arrest out of the hospital survive.

Researchers set up a community-based, multi-center clinical trial in 21 centers in the United States and three in Canada, and randomly assigned nearly 1,000 community units like apartment complexes, recreation centers, hotels and shopping malls to one of two groups.

One group was composed of volunteers trained in cardiopulmonary resuscitation, or CPR, and the second group was trained in CPR and in the use of automated external defibrillators, or AEDs, placed at strategic locations on-site. Both groups were part of a structured-and-monitored emergency response system that would recognize the symptoms of cardiac arrest and notify 911 promptly. The study sought to measure how many patients survived to hospital discharge among those who experienced cardiac arrest in the public areas.

More than 19,000 volunteer responders were trained for the study. The frequency of CPR performed by volunteers or bystanders was similar in the two groups, but volunteers in the CPR-plus-AED group activated the emergency system more frequently. Shocks were delivered with a public-access defibrillator or other non-emergency-medical services defibrillator in nearly 35 percent of the definite out-of-hospital cardiac arrests. The rate of hospital admission was higher in the CPR-plus-AED group.

More than 20 percent of out-of-hospital cardiac arrests happen in public locations. In public locations where an organized emergency response plan included trained and equipped volunteers to provide early defibrillation with an AED, the number of patients surviving to hospital discharge doubled, according to the study.

Laypersons can be trained to use automated external defibrillators, wrote VCU’s Ornato and study coordinator Alfred Hallstrom, Ph.D., of the University of Washington.