[On-scene times for helicopter services. Influence of central dispatch center strategy]

Previous studies have suggested that when using several emergency systems and air rescue prehospital and on-scene times are extended, depending on the dispatch strategy. Emergency medical services (EMS) in Germany are delivered by ambulances (AMB) staffed by paramedics alone or with physicians (EMD) and by helicopter emergency medical services (HEMS) always staffed by both. The advantages of HEMS in countries with short transport distances and high hospital density are controversial. The best dispatching strategy for HEMS has not been determined

The BoLuS study in the German state of Hessen was designed to evaluate the influence of dispatch strategy on prehospital times for responses involving both HEMS and EMS.

Rescue responses involving HEMS were prospectively evaluated in 12 regions of Hessen from July 2010 to September 2011. Although all regions had access to HEMS, only one had its own service. Data from both central dispatch centers and helicopter services were collected and combined to calculate the on-scene time (OST) and correlate it with dispatch strategy.

A total of 2111 emergency interventions were evaluated. Internal medicine emergencies accounted for 42.9 % of cases and trauma for 36.7 %. Just one patient was involved in 87.9 % of rescues. Two services were involved in 65.3 % of rescues and three or more in 31.5 %. The most common dispatch categories were initial dispatch of EMS and HEMS (50.6 %), initial dispatch of EMS with later request for HEMS (19.7 %) and initial dispatch of both EMS and EMD with later request for HEMS (17.4 %). The OST for these categories were 31.0 ± 13.7 min, 43.7 ± 16.2 min and 54.6 ± 21.3 min (p < 0.01), respectively.

OST varies significantly depending on the number of EMS involved and the dispatch strategy. Sequential dispatching of ground and later HEMS wastes time. Getting an emergency physician to the scene as quickly as possible, reducing transport time to an appropriate hospital and caring for more complex emergencies are the main indications for HEMS. If HEMS appears likely to be needed, it should be dispatched immediately.