MedicalResearch.com Interview with:
Dr. Timothy Chan
Timothy C. Y. Chan, PhD
Canada Research Chair in Novel Optimization and Analytics in Health
Associate Professor, Mechanical and Industrial Engineering
Director, Centre for Healthcare Engineering
Department of Mechanical & Industrial Engineering
Faculty of Applied Science & Engineering | University of Toronto
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: The immediate access to and use of an automated external defibrillator (AED) can increase the likelihood of survival from out-of-hospital cardiac arrest (OHCA). Currently, guidelines for AED deployment focus only on spatial factors, such as where to place AEDs with respect to cardiac arrest risk, and assume that the buildings housing the AEDs are open and accessible 24 hours a day. However, this is not the case in reality.
AED accessibility by time of day has largely been overlooked despite the fact that cardiac arrest incidence and survival vary by time of day and day of week. In this study we performed two main analyses, using data from Toronto, Canada.
First, we determined the impact of accessibility on cardiac arrest coverage. That is, we determined what fraction of OHCAs occurred near a registered AED, but when that AED was unavailable based on the hours of operation of the building.
Second, we developed a novel optimization model that identifies locations to place AEDs that maximize the number of out-of-hospital cardiac arrestswith an accessible AED nearby. We compared this approach to one where AEDs were placed guided by only spatial information.
We found that of the OHCAs occurring within 100 m of an AED, approximately 21% occur when the AED is inaccessible. Nearby AEDs were inaccessible for 8.6% of OHCAs during the day (8 a.m. – 3:59 p.m.), 28.6% in the evening (4 – 11:59 p.m.) and 48.4% at night (midnight –7:59 a.m.). When applying our optimization model to determine new AED locations, we achieved a 25.3% relative increase in the number of out-of-hospital cardiac arrests that occur near an accessible AED over the spatial-only approach. The relative increase was 10.9% during the day, 38.0% in the evening, and 122.5% at night.