Use of an ambulance-based helicopter retrieval service

Background: John Hunter Hospital is the major trauma centre for a region co vering more than 25 000 square kilometres. The helicopter primary retrieval service for trauma is paramedic staffed and protocol driven. The aim of th e present study was to assess the over-triage rate created by such protocol s, and to assess the benefit to patient outcomes that may be attributable t o the sen ice. 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 pane l reviewed the medical records for the 184 primary retrievals. Using a cons ensus model, estimates of time delay or saving were calculated and likeliho od of benefit, no benefit or harm was assessed. Results: A total of 3087 trauma patients were assessed at John Hunter Hospi tal 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 s core of 16 or greater. Twelve patients were discharged from Emergency and 3 6% 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 w ith minimal attributable benefit. Overall 1.7% of patients were felt to hav e 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, th e service provides benefit for the region, There is potential for harm, how ever, 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.