High-risk residential areas identified for defibrillator placement

Folke F. Circulation. 2010;122:623-630.

Issue: October 2010

Researchers were able to identify high-risk residential areas suitable for the placement of an automated external defibrillator by using simple demographic characteristics of a city center, according to a new study appearing in Circulation.

“According to the recommendations from the American Heart Association, 13 AEDs should be placed where there is a high likelihood of sudden cardiac arrest (≥one arrest every 5 years). Whereas a tremendous amount of resources has focused on deployment of AEDs in public locations, the majority of out-of-hospital cardiac arrests (OHCAs) take place in residential areas and remain not covered by publicly placed AEDs,” the researchers commented in their study. “Furthermore, little is known about how to identify residential areas with the highest risk of OHCA, let alone the possible cost of public access defibrillation in such areas.”

This led the group of Danish researchers to examine OHCAs (n=4,828) in Copenhagen from 1994 to 2005. They analyzed the incidence and characteristics of OCHAs in every 100-m × 100-m residential area, according to the demographic characteristics of the grid cells, information about age, level of education, population density and household income.

By combining at least two demographic characteristics, they determined 100-m × 100-m areas with at least one arrest every 5.6 years (characteristics included >300 people per area, lowest income) to one arrest every 4.3 years (characteristics included >300 people, lowest income, low education, highest age). The area with at least one arrest every 5.6 years covered 9% of all residential OCHAs, whereas the area of one arrest every 4.3 years covered 0.8%.

Additional data showed that individuals with OCHAs in residential locations differed from those in public areas in the following ways: patients were older (70.6 vs. 60.6 years), had less frequent ventricular fibrillation (12.8% vs. 38.1%) and had a worse 30-day survival rate (3.2% vs. 13.9%); the ambulance response interval was longer (6 vs. 5 minutes); and the arrests occurred more often at night (21.2% vs. 11.2%; P<.0001 for all comparisons).

“Using simple demographic characteristics of a city center, we were able to identify residential high-risk areas of OHCA suitable for AED placement. Such areas comprised 3% of all residential quarters, but included up to 9% of all residential OHCA,” researchers wrote. “However, individuals with OHCA in residential locations were more likely to have characteristics associated with a poor outcome, a finding emphasizing the necessity for strategic placement of AEDs if future public access defibrillation programs in residential areas are to succeed without excessive costs.”

As a way to overcome the obstacles impeding the success of public access defibrillations in residential areas, the researchers suggested, in addition to strategic placement and providing potential rescuers training in CPR and AED use, the establishment of local AED registries with information on location and availability of AEDs in the community to allow the emergency dispatcher to direct a rescuer to the nearest AED.

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