1 Department of Emergency Medicine, University of Michigan Medical School, 1500 East Medical Center Drive, Ann Arbor, MI 48109, USA.
2 Sunnybrook Center for Prehospital Medicine, Regions of Halton and Peel, 77 Browns Line, Suite 100, Toronto, Ontario M8W 3S2, Canada.
3 Department of Family and Community Medicine, Division of Emergency Medicine, University of Toronto, 500 University Avenue, 5th Floor, Toronto, Ontario M5G 1V7, Canada.
4 Department of Emergency Medicine and Services, Helsinki University Hospital and University of Helsinki, Helsinki, Finland.