Differences in Mortality and Morbidity in Patients Suffering a Time-critical Condition Between Ground Emergency Medical Services and Helicopter Emergency Medical Services - a Descriptive and Comparative Study

Background Efficient healthcare can be decisive for patients who suffer an out-of-hospital time-critical medical condition. If untreated these conditions can compromise health and even become life-threatening. The most common time-critical conditions assessed and treated in the prehospital environment are cardiac arrest, chest pain, stroke, severe respiratory difficulties and severe trauma. In addition to receiving rapid assessment and immediate treatment, it is also important that these patients are quickly transported to a location where they can receive the appropriate level of care.

If a person is suffering from an out-of-hospital time-critical medical condition, the emergency medical dispatch center is alerted when contacted by the use of '112' the emergency phone number common to European countries. An operator will answer the call and assess the situation using a medical criteria-based index . The operator will than dispatch the right resource, either Ground Emergency Medical Services (GEMS) or Helicopter Emergency Medical Services (HEMS).

The dispatching of HEMS has long been considered as a weak link in the chain of response. The use of HEMS is region specific and that the mechanism of injury is a poor predictor for HEMS dispatch. Dispatch criteria should be designed to match specific systems.

The prehospital care in Sweden has developed rapidly over recent decades. Prehospital care today is a system in which qualified prehospital care providers deliver advanced emergency healthcare. GEMS vehicles are staffed with at least one registered nurse (RN) and over the years programs has been developed, which leads to at postgraduate diploma in prehospital care nursing. GEMS has less access to medical-technical equipment for advanced medical life support and critical care. The HEMS medical staff consists of a RN with a postgraduate diploma in prehospital care nursing and a physician, specialized in anaesthesia and intensive care and HEMS is equipped for advanced life support and critical care interventions. All of Sweden´s Emergency Medical Services (EMS) organisations require educational programs and certification for prehospital trauma and emergency medical care on a yearly basis. These educational programs aim to improve emergency care based on evidence based medicine. Previous studies have demonstrated that EMS provides rapid access to the healthcare system, quality care on scene, and transport with support en-route to appropriate care if not provided on scene. An increased survival rate could be identified in trauma patients if transported by HEMS, compared to GEMS. Another study reported increased survival rate of patients over 55 years of age who suffered minor trauma and where transported by HEMS compared to GEMS. Previous studies has also shown an advantage in using HEMS in treating patients with acute MI, initiating treatment as early as possible. The time gained, using HEMS, in treating acute MI was reported to reduced mortality compared to patients treated by GEMS.

There is a steadily growing body of literature that describes the activities in both GEMS and HEMS and the assessment and treatment of Traumatic Brain Injury (TBI) and acute Myocardial Infarction (MI). But these studies are not generalisable to the Swedish prehospital environment, due to the importance of evaluating triage criteria for HEMS activation by local and regional authorities and the variation of health care system in which GEMS and HEMS operate. A systematic collection and analysis of incidence and outcomes in prehospital care of time-critical conditions can therefore increase dispatch accuracy and contribute to knowledge about which patients should be assessed and treated by GEMS and HEMS, respectively. This, in turn can lead to cost-effectiveness and better outcomes. Previous studies have been criticized for the low quality of evidence and variation in study methods, which overall has resulted in a lack of credibility in the conclusions of the studies.