Introduction: In Japan, the number of automated external defibrillators (AEDs) placed in public area has climbed up to the estimated 530,000. However, of ~120,000 out-of-hospital cardiac arrest (CA) cases annually, AEDs are used only in 1.5% cases by lay people. Objectives: The aim of this study was to evaluate the relation between the distance from the CA location to the nearest AED and utilization of AEDs in urban areas.
Methods: We calculated horizontal distances from out-of-hospital CA location to the nearest AED in large urban areas including the City of Kobe, Osaka and Nagoya from 2011 to 2015. We excluded CA cases occurred at residential facilities.
Results: During the study period, we detected 4,776 out-of-hospital CA cases and a total of 9,593 AEDs deployed in public area. In 679 (14.2%) CA cases, an AED was used or brought in place by lay people by the time emergency medical service personnel arrived on scene. When CA occurred within 100 m from the nearest AED, an AED was used or in place in 18.3% (446 / 2432) of the cases. The distance to the nearest AED was significantly shorter (median 63 m) in cases for which AEDs were used by lay people compared to cases for which AEDs were not used (median 101 m). The probability distribution of the distance from CA places to the nearest AED is shown in the figure. AEDs were used or brought in place less frequently when CA occur during the night time (0-8 am).
Conclusions: In public places of urban area, a half of out-of-hospital CA occurred within 100 m from public AEDs. However, AEDs were used or brought in place by lay people only in 20% of those cases. The probability of AED utilization seems related with the distance to the nearest AED.