Bystanders and AEDs make for life-saving duo

November 7, 2007

Bystanders and automated external defibrillators (AEDs) are a life-saving combination.

Bystanders and automated external defibrillators (AEDs) are a life-saving combination.

Data from the first-ever study of random bystanders using AEDs show that 36% of cardiac arrest victims treated by passersby walk out of the hospital alive. That is slightly better than the 30% survival rate when emergency medical services (EMS) personnel witness a cardiac arrest and use a manual defibrillator.

"This outcome is better than we anticipated," said Myron Weisfeldt, MD, chairman of medicine at Johns Hopkins University, Baltimore, and lead author. "We have some truly remarkable data here. It shows that there is no downside risk to using an AED."

Dr Weisfeldt and colleagues conducted a one-year population cohort study covering 11 urban and suburban areas in the United States and Canada with an aggregate population of 20 million. The study sites are part of the Resuscitations Outcomes Consortium (ROC), a network of communities involved in prehospital emergency care studies.

The 2005 Public Access Defibrillation (PAD) trial found that training nonmedical volunteers to use AEDs in community settings doubled the number of survivors following out-of-hospital cardiac arrest compared with training volunteers in CPR alone, Dr Weisfeldt said. The current study showed similar results when random volunteers used AEDs.

The 2007 report included 9897 individuals with non-traumatic out-of-hospital cardiac arrest between December 1, 2005 and November 30, 2006. All study participants received defibrillation by bystanders. EMS personnel evaluated patients upon arrival and gave CPR as needed.

Random bystanders who witnessed a cardiac arrest and used an AED boosted the odds ratio in favor of victim survival to 2.45. That survival advantage compares favorably with a 2.5 odds ratio in favor of survival when trained medical professional witness a cardiac arrest and use a manual defibrillator, Dr Weisfeldt said.

AED units cost about $2,000 each, plus installation and signage costs, he continued. That makes AEDs a highly cost effective intervention.

Bystander use of AEDs was divided evenly between public and private locations, Dr Weisfeldt said.

Uses typically occurred in private homes, healthcare facilities, public buildings, recreation facilities, highways and industrial settings. Extending the ROC study results to the general population, Dr Weisfeldt estimated that bystanders who administer AED save 412 lives annually across North America.

"We are seeing for the first time that survival in out-of-hospital cardiac arrests is improving," he said. "We are finally moving the needle."

An analysis of use suggests that an AED should be available in any location with an expected population of 500 or more during any eight-hour period, Dr Weisfeldt added. That includes schools, office buildings, larger physician practices and other healthcare facilities, recreational and exercise facilities, and athletic competitions at all levels.

"When you compare that to the cost of other safety measures required by law such as seat belts in automobiles and sprinkler systems to control fires in buildings, my own conclusion is that it's not an enormous expense," Dr Weisfeldt said. "We do many things in the name of public safety that are much more expensive than what a community-based AED program would cost."

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