Automated external defibrillators: Complementary medicine

Cardiology Review® Online, May 2007, Volume 24, Issue 5

Cardiac arrest (CA) is a leading cause of death in industrial countries, with approximately 350 000 fatal episodes each year in the United States alone.

Cardiac arrest (CA) is a leading cause of death in industrial countries, with approximately 350,000 fatal episodes each year in the United States alone. Most CAs occur out of hospitals and of those the great majority are in residential settings. This has led to community-wide efforts to organize emergency response systems involving bystanders, trained volunteers, and emergency personnel to administer basic life support. The results have been mixed, with some studies reporting an improvement in survival and others finding no significant benefit. The development of reliable automated external defibrillators (AEDs) has raised the prospect of early defibrillation by trained volunteers. The experience of 1 such program in Brescia (Italy) is the subject of a

Cardiology Review.

, which is summarized in this issue of The authors compared the survival of patients with an out-of-hospital CA before and after the addition of 49 AEDs to the existing defibrillation capability in Brescia county. A historical cohort of 692 consecutive patients was compared with a prospective cohort of 702 patients to determine whether 1-year survival free of neurological impairment is improved by AEDs. Secondary endpoints examined the influence of CA location (urban vs rural) time to defibrillation (< 8 min vs > 8 min), and cost effectiveness. The main finding was an increased 1-year survival after introduction of the AED program from 0.9% (95% HR; confidence interval [CI], 0.4-1.8) to 3.0% (CI, 1.7-4.3). One should note, however, that the 1-year follow-up period reflects not only the immediate survival (ie, survival to admission, 5.5% vs 8.1%), but also the subsequent medical care. Survival was better in an urban setting, probably due to a higher rate of witnessed events, higher population density per deployed AED, and shorter response time. This is supported by the observation that CA victims receiving defibrillation within 8 minutes fared markedly better than those whose defibrillation was delayed by more than 8 minutes (survival rate 12.5% vs 1.7%). In summary, the Brescia Early Defibrillation Study suggests that a structured emergency response program with AEDs operated by trained laypersons can contribute in the fight against CA. However, a number of questions remain: what is the optimal (ie, most cost effective) density of AEDs deployed in the community? Where should AEDs be placed to achieve acceptable response times? How can AEDs be used in residential settings where most (4 of 5) out-of-hospital CAs occur? What about patients who do not wish to be resuscitated?

study by Cappato and colleagues