Substantial resources are spent in providing emergency medical services to victims of out-of-hospital cardiac arrest. The science of pre-hospital medicine has advanced considerably over the past decade. Specifically, EMS services and medical directors have developed carefully designed protocols, intensive training, and very substantial resources, in attempting to improve the immediate outcomes in patients with out-of-hospital cardiac arrest. It is anticipated that approximately 200-400 patients per year in the Greater Toronto Area are successfully resuscitated by Emergency Medical Services personnel and be admitted to hospital with intact circulatory function.