Maryland’s Helicopter Emergency Medical Services Experience From 2001 to 2011: System Improvements and Patients’ Outcomes

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Helicopter emergency medical services (EMS) has become a well-established component of modern trauma systems. It is an expensive, limited resource with potential safety concerns. Helicopter EMS activation criteria intended to increase efficiency and reduce inappropriate use remain elusive and difficult to measure. This study evaluates the effect of statewide field trauma triage changes on helicopter EMS use and patient outcomes. Data were extracted from the helicopter EMS computer-aided dispatch database for in-state scene flights and from the state Trauma Registry for all trauma patients directly admitted from the scene or transferred to trauma centers from July 1, 2000, to June 30, 2011. Computer-aided dispatch flights were analyzed for periods corresponding to field triage protocol modifications intended to improve system efficiency. Outcomes were separately analyzed for trauma registry patients by mode of transport. The helicopter EMS computer-aided dispatch data set included 44,073 transports. There was a statewide decrease in helicopter EMS usage for trauma patients of 55.9%, differentially affecting counties closer to trauma centers. The Trauma Registry data set included 182,809 patients (37,407 helicopter transports, 128,129 ambulance transports, and 17,273 transfers). There was an increase of 21% in overall annual EMS scene trauma patients transported; ground transports increased by 33%, whereas helicopter EMS transports decreased by 49%. Helicopter EMS patient acuity increased, with an attendant increase in patient mortality. However, when standardized with W statistics, both helicopter EMS- and ground-transported trauma patients showed sustained improvement in mortality. Modifications to state protocols were associated with decreased helicopter EMS use and overall improved trauma patient outcomes.