In Japan, the number of automated external defibrillators (AEDs) installed in public spaces is increasing, but the use of AEDs for cardiopulmonary arrest (CPA) injuries and illnesses remains extremely limited. In this study, we used a geographic information system (GIS) to analyze the extent to which existing public access defibrillation system is able to capture CPA casualties in terms of space and time, based on information on the location and time of the CPA cases obtained from emergency records. In addition, we identified changes in accessibility when new AEDs were installed at post office ATMs in addition to existing AEDs. The results demonstrated that AED accessibility is significantly related not only to the constraint of the spatial proximity of AEDs, but also to the constraint of whether the time of CPA occurred was within the available time of the nearby AEDs. It also became clear that increasing the number of AEDs would only improve accessibility to a limited extent as long as time constraints existed.
