WEDNESDAY, July 29, 2009 (HealthDay News) -- Automated external defibrillators, or AEDs, can save the life of someone who is in cardiac arrest. So in what public spots should they be placed for maximum benefit?
In two new studies published online July 27 in Circulation, researchers focused on answering that question.
In cardiac arrest, the heart doesn't function, and without immediate cardiopulmonary resuscitation from someone, brain damage or death can occur in just four to six minutes. AEDs send an electric shock to the heart and allow it to return to a normal rhythm.
In one study, Seattle researchers found that schools that have AED programs have a high rate of survival for students and others who have sudden cardiac arrests on school grounds.
Of the 1,710 U.S. high schools with AED programs that were studied, 83 percent had an established emergency response plan for sudden cardiac arrest. About 40 percent practiced and reviewed plans with potential school responders at least yearly.
The researchers found 36 instances of sudden cardiac arrest at the schools studied, including 14 student athletes and 22 people who were not students. About 83 percent were given an AED shock, and 64 percent of all who had cardiac arrest survived at least to the point of being discharged from the hospital.
Schools were described as a "strategic location for AED programs to serve large concentrations of people at risk for sudden cardiac arrest," Dr. Jonathan Drezner, an associate professor of medicine at the University of Washington-Seattle and the study's lead author, said in a news release from the American Heart Association.
In the other study, Danish researchers checked whether AEDs were located where cardiac arrests occurred. About 25 percent of cardiac arrests that occur outside of a hospital happen in public places, they found.
Dr. Fredrik Folke and his colleagues digitally mapped the locations of all cardiac arrests that occurred in Copenhagen from 1994 through 2005. They compared this data with the locations of 104 AEDs placed in municipal institutions in the city.
According to the analysis, AED coverage in 10 percent of the city would cover about 67 percent of all cardiac arrests. The highest number of cardiac arrests happened in train stations, large shopping centers, central bus terminals, sports centers and other high-density areas.
"Our findings suggest that public access defibrillation programs should cover the greatest possible number of arrests in public, which is consistent with the recommendations from the American Heart Association," said Folke, lead author of the study and a cardiology research fellow at Gentofte University Hospital in Hellerup, Denmark.
"But if AED deployment in the community is driven by local or political initiatives and not on strategic AED placement, there is a high risk of AEDs being place primarily in low-incidence areas of cardiac arrest and, hence, low likelihood of the AEDs ever being used," he added.
The American Heart Association has more on CPR guidelines.