Air medical scene response to blunt trauma: effect on early survival

Objective: To assess the impact of on-scene treatment by an experienced critical care physician on prehospital resuscitation, the initial hospital phase and early survival of patients with major blunt trauma. Design, setting and participants: (i) Historical cohort of patients with trauma treated on scene by a helicopter emergency medical service (HEMS), 1986-1994, comparing medical and paramedical treatment and outcomes. (ii) Comparison of a subgroup of 77 patients (injury severity score [ISS] greater than or equal to 15) treated by the air medical team (AMT) with (a) an ISS-matched group of 308 patients treated by ground paramedics (GPMs) and (b) the Major Trauma Outcome Study cohort. Main outcome measures: Procedural requirements assessed by the Therapeutic Intervention Scoring System (TISS), comparing resuscitation by medical and ambulance personnel; and observed versus expected mortality. Results: (i) Of 445 patients treated on scene, 270 (61%) had sustained trauma, and 215 of these received early management by the AMT. Problems with ventilation or with volume resuscitation were encountered by general duties ambulance personnel (40%) and paramedics (60%) before arrival of the AMT. (ii) Matched patients treated by GPMs required significantly more emergency department interventions on arrival at hospital (P< 0.01), and were possibly more likely to die in the first 48 hours (relative risk of death, 1.43; 95% confidence interval, 0.74-2.78) than patients treated by the AMT. Comparing the AMT-treated patients with the Major Trauma Outcome Study cohort, 9 deaths occurred of the 18 that were predicted - a 50% reduction in predicted deaths (Z = 3.38; P<0.001) - and there were 11 unexpected survivors and one unexpected death. The adjusted "W" statistic was 12.18 tie, there were 12 more survivors per 100 patients than the Major Trauma Outcome Study prediction, after adjustment for casemix. Conclusions: As part of the air medical team for response to major blunt trauma, a physician can provide significantly improved prehospital stabilisation, especially in airway and ventilatory control. Our results suggest improvement in mortality in AMT-treated patients, probably due to the enhanced procedural capabilities of physicians, despite longer prehospital times.