The primary research question is as follows: Does pre-hospital initiation of therapeutic hypothermia by EMS providers increase the proportion of comatose out of hospital cardiac arrest patients with return of spontaneous circulation (ROSC) that are successfully cooled to a target temperature of 32 to 34 degrees Celsius within 6 hours of emergency department arrival, compared to usual post-resuscitation care provided in the field? The primary outcome is the proportion of included patients that are successfully cooled to reach target temperature of 32 to 34 degrees Celsius within 6 hours of emergency department arrival.