Richard M. Lyon, Joe Vernon, Magnus Nelson, Neal Durge, Malcolm Tunnicliff, Leigh Curtis, Malcolm Q. Russell

Major trauma commonly occurs at night. Helicopter emergency medical services (HEMS) can provide advanced prehospital care to victims of major trauma but do not routinely operate at night in the United Kingdom. We sought to prospectively examine the need for a night HEMS service in Kent, Surrey, and Sussex in the United Kingdom. A 4-month, prospective study was conducted (July 1, 2012-October 31, 2012). HEMS dispatch paramedics were present in the ambulance dispatch center and undertook simulated HEMS activations when a suitable case was identified. All trauma cases from the 4-month study period were collated. Five independent HEMS clinicians reviewed the simulated tasking and trauma cases and gave an opinion on whether the patient met HEMS activation criteria. A mission rate of 1 case per night was predefined as cost-effective. During the prospective study, 145 calls were identified by the HEMS dispatch paramedic as appropriate for an HEMS response. If HEMS had deployed to all 145 incidents, this would have resulted in an average mission rate of 1.2 activations per night. Two hundred eight incidents were identified as potentially appropriate for HEMS activation. Responding to all 208 incidents would have resulted in a mean activation rate of 1.7 per night. This study justifies the need for Kent, Surrey and Sussex Air Ambulance Trust to operate a service at night for a trial period, with an estimated average mission load of 1 per night spread over the entire night period. Further research is warranted to determine the potential impact of a night HEMS service on outcome from major trauma.