Nationwide study tests effectiveness of easy access to portable defibrillators

November 28, 2000

Physicians from the University of Chicago are seeking from 40 to 80 large sites in and around Chicago to participate in the Public Access Defibrillator (PAD) Trial, a massive nationwide study that will determine whether trained non-medical volunteers with easy access to small portable defibrillators can increase survival for those who suffer a cardiac arrest.

In the United States, about 350,000 people die suddenly and unexpectedly each year from cardiac arrest. That comes to nearly 1,000 people a day or almost one a minute--ten per day in Chicago alone.

Prompt treatment of victims of sudden cardiac arrest, including rapid use of a defibrillator to jolt the heart back into a normal rhythm, can prevent as many as half of these deaths. But cardiac arrest survival rates have remained quite low in the United States, around five percent.

The rates are even lower in most big cities, where crowds, traffic and high-rise buildings compound the other delays. In Chicago, for example, fewer than two percent of the victims of an out-of-hospital cardiac arrest survive.

"Each minute of delay drops the odds of survival by seven to 10 percent," said Michael Sayre, MD, associate professor of clinical medicine at the University of Chicago, a member of the University's Emergency Resuscitation Research Center, and director of the Chicago arm of the PAD trial. "The shock should ideally be given in the first three minutes," he said.

Despite rapid response systems, emergency medical personnel rarely get to a victim that soon. Nationwide, the average time from collapse to first shock is more than six minutes.

This study is designed to see if trained volunteers in key locations can get the devices to the people who need them quickly enough, if that will save lives and reduce complications, and if it can be done at a reasonable cost.

Recent studies performed at O'Hare and Midway Airports and several Las Vegas casinos have confirmed that rapid treatment with portable defibrillators can dramatically increase survival rates.

The 24-city, 1000-site PAD trial--funded by the National Heart, Lung, and Blood Institute, the American Heart Association, and the manufacturers of automatic defibrillators--should determine if this approach is both feasible and cost-effective on a much larger scale.

"We know that just putting hundreds of these devices out there is not adequate," said Sayre. "A successful program will require training thousands of non-medical volunteers in key locations to recognize a cardiac arrest, call 911, begin CPR and use the defibrillator promptly."

The portable, public access defibrillators are no bigger than a laptop computer. They are easy to use and are designed to eliminate the risk of accidental or intentional misuse. They will not deliver a shock unless they detect an abnormal heart rhythm.

Potential trial sites include any place where at least 250 people age 50 or older spend a lot of time, such as shopping malls, museums, large apartment buildings or hotels. There should be enough on-site volunteers who are not health care professionals to be able to begin CPR and apply a defibrillator within three minutes of notification.

For the proposed study in Chicago, more than 20 locations, such as the Museum of Science and Industry, four senior centers administered by the City of Chicago Department of Aging, and the Lyric Opera of Chicago, have already expressed interest.

Because this is a controlled trial, designed to assess the impact of the portable defibrillators, volunteers at every site will receive training in how to recognize and respond to a cardiac arrest, but only half of the sites will also be supplied with the devices.

After two years, the study will compare the results from sites with defibrillators to those without. The study will focus on survival to hospital discharge, changes in mental status (many cardiac arrest survivors suffer neurological damage if the blood supply to the brain is disrupted for too long), health-related quality of life, and costs.

Unlike most clinical research projects, patients involved in the PAD Trial may not have the chance to give their informed consent prior to treatment. All aspects of the proposed investigation, including the consent process and public notification prior to beginning the research, must be approved by the University's Institutional Review Board.

All patients will be notified about the study as soon as possible after treatment for cardiac arrest; patients who survive to hospital admission will be asked to consent to the follow-up studies involving neurological evaluation, quality of life measures and economic surveys.

Any one who has questions or concerns about the proposed trial should call the Public Access Defibrillator Study at (773) 834-7232.