Most public automated external defibrillators are in buildings that aren’t open 24 hours. As a result, bystanders who are near AEDs don’t have access to the life-saving defibrillators in 21 percent of out-of-hospital cardiac arrests, according to a study presented at the American Heart Association’s Scientific Sessions 2015.

Researchers analyzed cardiac arrests that occurred within 100 meters (328 feet) of a public AED in a Canadian city. They then analyzed AED coverage of out-of-hospital cardiac arrest for more than eight years, according to the time of day and day of week.

When there was no 24/7 access to buildings, researchers found AED coverage was diminished more than:

  • 8 percent during the day;
  • 28 percent in the evening; and
  • 48 percent at night.AED access was limited in schools, industrial facilities, recreational facilities and offices, while there was round-the-clock access in long-term care homes and transportation facilities.
  • Researchers suggest that a facility’s 24/7 access should be considered when choosing public AED locations, and that this information can be used in a mathematical approach to determine public AED locations that maximize coverage.
  • Most out-of-hospital cardiac arrests in the study (61 percent) occurred during evenings, nights and weekends.

“The greatest success for AEDs has been when they were in clearly labeled public spots: on the wall in airports, for example. I think any place where people gather would be beneficial: shopping malls, parking structures, and religious buildings for example,” said Clifton Callaway, M.D., Ph.D., professor and executive vice-chair of Emergency Medicine & Ronald D Stewart Endowed Chair of Emergency Medicine Research at the University of Pittsburgh School of Medicine. “The key is to have the device outside of any locked doors, just like a fire extinguisher on the wall.”

There is no complete national mapping of AED locations, but many parallel efforts are ongoing in sections of the U.S. and Canada which can be found online.

“Apps are already available that can deliver this information to you as a rescuer,” said Callaway, a volunteer for the American Heart Association. “These use the GPS location of your phone to tell you what devices are nearby. I have several on my phone, and try to see what is available when I travel.  Unfortunately, a comprehensive list is still not available in my own city, but we are working to fix that.”

Other products integrate with the 911 center, said Callaway, explaining that they inform 911 dispatchers when a call comes in for help.

“The 911 call taker and dispatcher can then provide this information to the caller,” he said.

AED placement has a hurdle, regardless, because the majority of cardiac arrests outside of the hospital occur in homes.

“We are a long way from having an AED in every home. However, if I lived in a large apartment building, I would want one at least in the lobby,” said Callaway.