1. Department of Emergency Medicine, Ottawa Health Research Institute, University of Ottawa, Ottawa, Ontario, Canada
2. Medtronic Emergency Response Systems, Redmond, Wash
3. Clinical Epidemiology Program, Ottawa Health Research Institute, University of Ottawa, Ottawa, Ontario, Canada
4. University of British Columbia, Vancouver, British Columbia, Canada
5. Windsor Base Hospital, Windsor, Canada
6. Emergency Medical Services, Edmonton, Canada
7. Vancouver Fire Department, Vancouver, Canada
8. Department of Epidemiology and Community Medicine, Ottawa Health Research Institute, University of Ottawa, Ottawa, Ontario, Canada