title: Use of an ambulance-based helicopter retrieval service.
abstract: BACKGROUND
  John Hunter Hospital is the major trauma centre for a region covering more than 25,000 square kilometres. The helicopter primary retrieval service for trauma is paramedic staffed and protocol driven. The aim of the present study was to assess the overtriage rate created by such protocols, and to assess the benefit to patient outcomes that may be attributable to the service.
  
  
  METHODS
  The John Hunter Hospital trauma database was used to identify all cases arriving by helicopter in 1996, as well as their demographic details, injury severity score, details of the accident and outcome. An expert panel reviewed the medical records for the 184 primary retrievals. Using a consensus model, estimates of time delay or saving were calculated and likelihood of benefit, no benefit or harm was assessed.
  
  
  RESULTS
  A total of 3087 trauma patients were assessed at John Hunter Hospital in 1996, of which 8% arrived by helicopter. Of the primary retrievals, 67.6% had an injury severity score of 9 or less, with only 17.9% having a score of 16 or greater. Twelve patients were discharged from Emergency and 36% were discharged within 48 h. The overall mortality was 5.0%. Twenty-five per cent of patients were retrieved within 35 km of John Hunter Hospital with minimal attributable benefit. Overall 1.7% of patients were felt to have been potentially harmed, 17.3% to have benefited and 81.0% to have had no attributable benefit related to the helicopter use.
  
  
  CONCLUSIONS
  Although the majority of retrievals are for minor injuries, the service provides benefit for the region. There is potential for harm, however, where base hospitals are overflown in situations where patients have airway compromise, and where patient transfer is delayed due to helicopter activation. Primary helicopter tasking to trauma cases within 35 km of the major trauma centre is seldom beneficial.
authors.affiliation: John Hunter Hospital, New Lambton Heights, New South Wales, Australia.
authors.forename: V L
authors.initials: VL
authors.lastname: Wills
authors.forename: L
authors.initials: L
authors.lastname: Eno
authors.forename: C
authors.initials: C
authors.lastname: Walker
authors.forename: J S
authors.initials: JS
authors.lastname: Gani
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017732:Air Ambulances / Q000458:organization & administration / Q000706:statistics & numerical data*; D016009:Chi-Square Distribution; D002648:Child; D019992:Databases as Topic; D004634:Emergency Medical Technicians; D004636:Emergency Service, Hospital; D005260:Female; D006801:Humans; D015601:Injury Severity Score; D008297:Male; D008875:Middle Aged; D009517:New South Wales / Q000453:epidemiology; D010351:Patient Discharge; D012189:Retrospective Studies; D015996:Survival Rate; D013997:Time Factors; D014187:Transportation of Patients / Q000458:organization & administration / Q000706:statistics & numerical data*; D014193:Trauma Centers; D016896:Treatment Outcome; D014218:Triage; D000078329:Workforce; D014947:Wounds and Injuries / Q000628:therapy*