Out-of-Hospital Defibrillation by Trained Lay Volunteers Doubles Survival

Charlene Laino

November 12, 2003

Nov. 12, 2003 (Orlando) — Training nonmedical volunteers to use automatic external defibrillators (AEDs) as well as to perform cardiopulmonary resuscitation (CPR) approximately doubles the survival rate of patients with out-of-hospital cardiac arrest compared with training volunteers in CPR alone, a large prospective, randomized controlled study shows.

The Public Access Defibrillation (PAD) trial, presented here Tuesday at the American Heart Association (AHA) Scientific Sessions, showed that over an average of 21.5 months, 29 of 129 victims of cardiac arrest survived to hospital discharge in the group assigned to CPR plus AED, compared with only 15 of 103 victims in the group that received CPR alone.

The study, funded by the National Heart, Lung, and Blood Institute (NHLBI), also showed that successful resuscitation in residential units — regardless of whether volunteers are trained to use the defibrillators — was rare, reported Joseph P. Ornato, MD, chairman of the PAD Steering Committee and professor and chairman of the Department of Emergency Medicine at the Virginia Commonwealth University Medical Center in Richmond.

Noting that 80% of the 460,000 out-of-hospital cardiac arrests each year in the U.S. occur in the home, Dr. Ornato said the ultimate question is whether having AEDs at home will save more lives. The NHLBI is funding the 7,000-patient Home AED Trial (HAT) to answer that question, and added that PAD is a "bridge to a next step while we await those results."

The PAD trial was undertaken to evaluate whether adding AEDs to a CPR-based community volunteer response system would increase survival in individuals who have out-of-hospital cardiac arrest. Twenty-four participating centers identified a total of 993 large community units that had an estimated 50% risk of experiencing at least one out-of-hospital cardiac arrest per year. Of the eligible units, 24% were shopping centers, 24% were recreation centers, 15% were residential units, 9% were entertainment complexes, 7% were community centers, 7% were office complexes, and 14% were hotels, factories, transit centers, and other facilities.

Each study unit was randomly assigned to train volunteers in CPR alone or in CPR plus use of an AED. In addition to initial training, most of the 19,762 volunteers were retrained once or twice throughout the study period. Physicians, nurses, and other trained medical personnel, including emergency medical service personnel, were excluded from the study.

Over the next 21.5 months, there were 103 out-of-hospital cardiac arrests in the CPR-only group and 129 in the CPR plus AED group. Fifteen patients in the CPR-only arm survived to hospital discharge compared with 29 in the CPR plus AED arm ( P = .042).

Event characteristics, including mean patient age (72 years in the CPR-only group vs. 69 years in the AED group), indoor location (82% vs. 76%), nonsedentary activity at time of arrest (66% in both groups), witnessed event (68% vs. 76%), and initial rhythm ventricular fibrillation (47% vs. 39%), were similar in both groups. Also, 65% of those in the CPR-only group were men compared with 70% of those in the AED group.

A subanalysis demonstrated a similar doubling of the survival rate among persons treated at nonresidential units, with 14 survivors in the CPR-only group compared with 28 survivors in the AED group ( P < .74).

But when it came to residential units, there was only one survivor in each group, Dr. Ornato reported.

"Residential units accounted for 15% of the total units, but less than 5% of survivors," he said. "So what does that mean for the home environment? Not much."

The reason: The residential units in which the AEDs were placed in the study were gated communities and large apartment complexes whose environments do not simulate those in the home, Dr. Ornato said.

Jerry Potts, PhD, director of science for ECC Programs at the AHA's national office in Dallas, Texas, agreed. Also, the study may not have had the power to detect a difference in survival among residential units because the numbers were so low, he said.

In addition, people who suffer a cardiac arrest in a residential unit would have a much lower chance of having their arrest witnessed, thereby decreasing their chance of being successfully resuscitated, than a victim in a shopping mall or other public place, Dr. Potts said.

The trial also showed that PAD is extremely safe, with an adverse event rate of 0.2% in the CPR-only group and 0.3% in the AED group. There were no cases in which a person was inappropriately shocked or failed to be shocked when clinically indicated, Dr. Ornato said.

Cardiologists at the meeting were enthusiastic about the results.

Raymond J. Gibbons, MD, chairman of the AHA Committee on Scientific Sessions Program and Arthur and Gladys D. Gray Professor of Medicine at Mayo Medical School in Rochester, Minnesota, said the trial is extremely important from a public health viewpoint, "clearly demonstrating the value of training people to use AEDs in the kinds of public places that were described." He said he expects the AHA to help spearhead efforts to get more AEDs in public spaces and train additional volunteers.

Training is simple, Dr. Gibbons said, with studies showing that even eighth graders can be taught to use the device correctly.

Pointing to the device's "perfect safety record" in the public setting of the trial, Dr. Potts said, "The study also gives us a lot of confidence that safety is high when used by trained lay people."

AHA 2003 Scientific Sessions: Plenary Session III, Late-Breaking Clinical Trials. Presented Nov. 11, 2003.

Reviewed by Gary D. Vogin, MD

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