emergency medical services (EMS), a network of services coordinated to provide aid and medical assistance, from primary response to definitive care, involving personnel trained in the rescue, stabilization, transportation, and advanced treatment of traumatic or medical emergencies. Linked by a communication system that operates on both a local and a regional level, EMS is a tiered system of care, which is usually initiated by citizen action in the form of a telephone call to an emergency number. Subsequent stages include the emergency medical dispatch, first medical responder, ambulance personnel, medium and heavy rescue equipment, and paramedic units, if necessary. In the hospital, service is provided by emergency department nurses, emergency department physicians, specialists, and critical care nurses and physicians. See also emergency medical technician–advanced life support, emergency medical technician–intermediate, emergency medical technician–intravenous, emergency medical technician–paramedic.
