title: Factors at the scene of injury associated with air versus ground transport to definitive care in a state with a large rural population.
abstract: BACKGROUND
  Once emergency medical services (EMS) personnel decide to transport a trauma patient directly to definitive care, the next key decision at the scene of injury is whether to transport by air or ground.
  
  
  OBJECTIVE
  The aim of this study was to identify factors at the scene of injury that are associated with this decision.
  
  
  METHODS
  All trauma patients transported directly to a level I or level II trauma center by either air or ground EMS over a four-year period were selected from the Oklahoma State Trauma Registry. Initial scene vital signs, Glasgow Coma Scale score (GCS), injury mechanism, anatomic triage criteria, age, time of day, ground EMS service level, and scene location were collected. Scene location ZIP code centroids were geocoded and used to calculate distance to the trauma center. Following bivariate analyses, multivariable logistic regression models were developed within three strata defined by distance (>35, 16-35, and <16 miles).
  
  
  RESULTS
  More than 80% of the patients beyond 35 miles were transported by air, compared with 32% from 16-35 miles and only 4% from <16 miles. Regardless of distance, patients transported by helicopter tended to be younger, more often had abnormal vital signs, and more frequently came from areas served by a basic or intermediate ground EMS agency, as compared with patients transported by ground. Within each distance stratum, patients injured in severe motor vehicle crashes, motorcycle crashes, or pedestrian incidents were more likely to be transported by air. A GCS <14 was the only patient-related factor consistently associated with increased odds of air transport.
  
  
  CONCLUSIONS
  Distance is the main factor in deciding whether to use air or ground EMS to transport a trauma patient from the scene of injury to a trauma center. With the exception of GCS <14, injury etiology was more strongly and consistently associated with the decision to transport by air than were patient related-factors. Identifying factors influencing the field transport decision will help develop transport guidelines that make efficient use of EMS resources.
authors.affiliation: Emergency Systems, Oklahoma State Department of Health, Oklahoma City, Oklahoma 73117–1299, USA. kenneth@health.ok.gov
authors.forename: Kenneth E
authors.initials: KE
authors.lastname: Stewart
authors.forename: Linda D
authors.initials: LD
authors.lastname: Cowan
authors.forename: David M
authors.initials: DM
authors.lastname: Thompson
authors.forename: John C
authors.initials: JC
authors.lastname: Sacra
mesh_terms: D000063:Accidents, Traffic / Q000706:statistics & numerical data*; D000328:Adult; D017732:Air Ambulances / Q000706:statistics & numerical data*; D001336:Automobiles / Q000706:statistics & numerical data*; D004632:Emergency Medical Services; D005260:Female; D005843:Geography; D015600:Glasgow Coma Scale; D006801:Humans; D008297:Male; D015999:Multivariate Analysis; D009825:Oklahoma / Q000453:epidemiology; D012042:Registries; D012424:Rural Population / Q000706:statistics & numerical data*; D014218:Triage / Q000379:methods; D014947:Wounds and Injuries / Q000453:epidemiology*