True Public Access Defibrillator Coverage is Overestimated

Background: Out-of-hospital cardiac arrests (OHCAs) occur at all times of the day and night. Immediate access to an AED increases survival. However, most public-location AEDs are placed in buildings without 24 hour access. Objective: To measure fixed-location public AED coverage of OHCAs by time of day and day of week in a Canadian urban setting. Methods: We identified all atraumatic public OHCAs occurring in Toronto, Canada from Jan. 2006 – Aug. 2014. We obtained a list of registered AEDs from Toronto Emergency Medical Services as of March 2015 and determined the hours that each AED was available based on operating hours of the building housing the AED. We counted the number of OHCAs that occurred within 100 m of an AED (“assumed 24/7 coverage”) and the number that occurred both within 100 m of an AED and when the AED was available (“actual coverage”). Statistical analysis was performed using a [chi]2 test. Results: We identified 2440 atraumatic public OHCAs and 737 registered AED locations. A total of 451 OHCAs were covered under assumed 24/7 coverage. In terms of actual coverage, 354 OHCAs were covered, representing a coverage loss of 25.5%. The figure shows coverage decreased by 8.6% during the day (8am-3:59pm), 28.6% in the evening (4pm-11:59pm), and 48.4% at night (12am-7:59am); the differences were statistically significant (p