Prehospital response model and time to CT scan in blunt trauma patients; an exploratory analysis of data from the head injury retrieval trial

Alan A Garner, Kristy P Mann, Elwyn Poynter, Andrew Weatherall, Susan Dashey, Michael Puntis, Val Gebski

It has been suggested that prehospital care teams that can provide advanced prehospital interventions may decrease the transit time through the ED to CT scan and subsequent surgery. This study is an exploratory analysis of data from the Head Injury Retrieval Trial (HIRT) examining the relationship between prehospital team type and time intervals during the prehospital and ED phases of management. Three prehospital care models were compared; road paramedics, and two physician staffed Helicopter Emergency Medical Services (HEMS) - HIRT HEMS and the Greater Sydney Area (GSA) HEMS. Data on prehospital and ED time intervals for patients who were randomised into the HIRT were extracted from the trial database. Additionally, data on interventions at the scene and in the ED, plus prehospital entrapment rate was also extracted. Subgroups of patients that were not trapped or who were intubated at the scene were also specifically examined. A total of 3125 incidents were randomised in the trial yielding 505 cases with significant injury that were treated by road paramedics, 302 patients treated by the HIRT HEMS and 45 patients treated by GSA HEMS. The total time from emergency call to CT scan was non-significantly faster in the HIRT HEMS group compared with road paramedics (medians of 1.9 hours vs. 2.1 hours P = 0.43) but the rate of prehospital intubation was 41% higher in the HIRT HEMS group (46.4% vs. 5.3% P < 0.001). Most time intervals for the GSA HEMS were significantly longer with a regression analysis indicating that GSA HEMS scene times were 13 (95% CI, 7-18) minutes longer than the HIRT HEMS independent of injury severity, entrapment or interventions performed on scene. This study suggests that well-rehearsed and efficient interventions carried out on-scene, by a highly trained physician and paramedic team can allow earlier critical care treatment of severely injured patients without increasing the time elapsed between injury and hospital-based intervention. There is also indication that role specialisation improves time intervals in physician staffed HEMS which should be confirmed with purpose designed trials.