Diversion of ambulances by hospital emergency departments has become a day-to-day occurrence in many jurisdictions within Canada. Yet, despite the increasing prevalence of this phenomenon, its impact on transported patients, on the EMS system, and on the health care system overall has not, to date, been well quantified. Despite the increasing sophistication and capabilities of North American EMS systems, it is difficult to argue with the principle that unstable or potentially unstable patients are best served by expeditious transport for definitive care to acute care facilities. T o this end, this study represents an effort to assess the systemic and patient care impacts of ambulance diversions.

Patient-care and corresponding ambulance trip records for all patients transported by this EMS system for a five week period were abstracted to identify those patients in which an ambulance was diverted from its initial destination. Adverse events include hypotensive episodes, airway compromise, changes in level of consciousness, and the onset of violent behavior. Response and transport times also were abstracted, comparisons utilized student's t-test and 95% Confidence Intervals. Results: Ambulance diversions increased EMS response times and prehospital transport times. Adverse medical events occurred during 4.3% of diverted ambulance runs. Patients, when faced with the prospect of transport to other than their hospital of choice, not infrequently cancelled EMS transport and sought other means of transport. Subsequent interfacility transport was required for 4.3% of the diverted patients.

Diversion of ambulances impacts the EMS system by increasing response and transport times; the region, by generating subsequent interfacility transports; and patients, as adverse medical events can occur during the diverted transport.