W. A. Smedley2, J. D. Kerby3, P. L. Bosarge3, D. B. Cox3, R. L. Griffin4, S. W. Stephens5, K. L. Stone2, J. O. Jansen3 1University Of Alabama at Birmingham,Division Of Acute Care Surgery,Birmingham, Alabama, USA 2University Of Alabama at Birmingham,School Of Medicine,Birmingham, Alabama, USA 3University Of Alabama at Birmingham,Center For Injury Science, Division Of Acute Care Surgery, Department Of Surgery,Birmingham, Alabama, USA 4University Of Alabama at Birmingham,Department Of Epidemiology, School Of Public Health,Birmingham, Alabama, USA 5University Of Alabama at Birmingham,Alabama Resuscitation Center, Department Of Emergency Medicine,Birmingham, Alabama, USA
Introduction: Helicopters are an essential part of emergency care systems in the United States and every year thousands of critically ill patients rely on air transport for survival. Trauma systems, in particular, have been developed around the concept of taking the patient directly to definitive care. However, in many locations, ground EMS are dispatched to the scene of an incident first, to assess the patient, and then call for a helicopter if needed. The time to definitive care therefore includes the helicopter’s flight “out” (to the scene), as well as flight “in” (to the trauma center). In addition to flight time, “mission ground time” (launch, landing, loading, and takeoff) has to be considered. As a result, the area and population from which casualties can be taken to level I and II trauma centers within a set time is often smaller than expected. We hypothesized that the primary dispatch of helicopters, to selected incidents, would increase the number of residents who might benefit from aeromedical retrieval. The aim of this study was, therefore, to compare the population coverage of these two models of service delivery in a single state.
Methods: Geospatial analysis was utilized and based on georeferenced population data obtained from the U.S. Census Bureau. Ground-EMS-first coverage was calculated using elliptical coverage areas based on the location of helicopter bases, and level I and II trauma centers, using Microsoft Excel and arcGISTM. Heli-first coverage was evaluated by calculating circular isochrones around level I and II trauma centers, with a radius of 60 minute flight time, assuming a cruising speed of 246 km/hr.
Results: A heli-first policy would permit 4,633,063 residents, or 97% of the state’s population, to reach a level I trauma center within one flight hour. Furthermore, the state’s entire population would be able to reach a level I or II trauma center within one hour. This is in contrast to the traditional Ground-EMS-first approach which, under optimal conditions, permits 27% of the state’s population to reach a level I trauma center, and 60% of the state’s population to reach a level I or II within one hour.
Conclusion: Dispatching a helicopter as a first response is a contemporary approach to patient transport that provides relative quick access to specialist care for a large proportion of the population. However, such a policy would require additional, costly aeromedical resources. Our modelling only considers the “inbound” travel time, and not the time to reach a casualty, which may be short when local resources are used. Combined dispatch of local ground EMS units, and helicopters, may be optimal, but requires further study.
