Public Access Defibrillator LOCation (PADLOC)

1. What is this study?

This study aims to evaluate public locations at high risk for cardiac arrest in Toronto and the Peel Region. This will help us in creating an evidence-based map to guide future placement of public access defibrillators (PAD). In collaboration with researchers at the Department of Engineering, University of Toronto, we hope to optimize Automatic External Defibrillator (AED) placement using mathematical modeling. We are also evaluating current AED placement by determining a site risk estimate for each location that has a registered AED. This will allow us to report the proportion of registered AEDs which have been placed appropriately at high risk sites. In addition, we are looking into locating unregistered AEDs in an effort to quantify and characterize all existing AED sites in Toronto, and to encourage all AED administrators to register with Toronto Emergency Medical Services (EMS).

2. Why bother doing this study?

There are approximately 2300 EMS-attended out of hospital cardiac arrests (OHCAs) occurring within the City of Toronto every year. Of these, approximately 30% occur in a public, non-residential setting. The chain of survival relies on lay responders and EMS to initiate the potentially life-saving procedures of CPR and defibrillation. Placement of AEDs to provide for public access defibrillation holds the promise of shortening time from collapse to shock, thereby improving survival. Even a small decrease in time from collapse to shock is a major factor in the survival rate. Because it is not realistic to place an AED in every public location, identification of those places in which cardiac arrest most frequently occurs should guide the location of public access defibrillators to maximize their usefulness.

Toronto EMS has developed a PAD implementation program for the City of Toronto (http://torontoemssafecity.com). AEDs are integrated with EMS by registering its location with emergency dispatch centres. With the use of computer-assisted dispatch, operators taking 911 calls receive real-time notification regarding the presence of a registered AED on site. This provides an opportunity for the operator to facilitate the appropriate use of the registered AED. To date, there are over 700 AEDs registered in this manner. However, their deployment has not been guided by formal assessments of site risk for OHCA. The number of unregistered AEDs in the community placed through direct purchase from the manufacturer or CPR training organizations is unknown.

3. What cases are eligible?

All non-traumatic, EMS-treated, public location OHCAs from December 1, 2005 to November 30, 2010 occurring within the City of Toronto will be considered for inclusion in the study. “Public location” will be defined as all non-residential areas accessible to the public. This includes all outdoor locations, public transportation sites, commercial, civic and industrial sites, schools, public spaces, recreational areas, and out-of-hospital health care clinics. Cardiac arrests which occurred in outdoor locations immediately adjacent to residential buildings (e.g. sidewalk or yardof a house) will be excluded. Cardiac arrests which occurred in vehicles other than public transportation will be excluded. These criteria ensure that only publicly occurring OHCAs are included.

4. How will the study be conducted?

The study will use Epistry data to track the location of OHCAs in Toronto. We will classify locations into categories that will be informative for potential AED administrators and decision makers in deciding where to place the machine. Examples of categories will include airports, train stations, jails, factories, non-retail offices, civic buildings, shopping malls, restaurants, fitness clubs, medical offices, golf courses, beaches, and parks. Using a database which will give us an inventory of building types in Toronto, the site risk for OHCA will be estimated by dividing the number of OHCA per category site by the total number of that building type in the city. Based on this determination, site categories will be ranked by average annual incidence of cardiac arrest per site. Those with ≥0.2 cardiac arrests per year per site will be defined as “high risk”, and those with <0.2 cardiac arrests per year per site will be defined as “lower risk”.

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