Association Between Mode of Transportation and Outcomes in Penetrating Trauma Across Different Prehospital Time Intervals: A Matched Cohort Study.

BACKGROUND: National guidelines do not provide recommendations concerning optimal dispatch time for helicopter emergency medical services (HEMS) in the United States.

OBJECTIVES: This study describes the association between mode of transport (ground vs. helicopter) and survival of patients with penetrating injury across different prehospital time intervals and proposes evidence-based time-related dispatch criteria for HEMS.

METHODS: A retrospective matched cohort study was conducted using the 2015 National Trauma Data Bank. Adult patients (age ≥ 16 years) with penetrating injuries were included. Patients transported via HEMS were selected and matched (1 to 1) for 17 variables to patients transported by ground ambulance (GEMS). Bivariate analyses were conducted to compare characteristics and outcomes (survival to hospital discharge) of patients across different prehospital time intervals.

RESULTS: Each group consisted of 949 patients. Overall survival rate was similar in both groups (90.6% for HEMS vs. 87.9% for GEMS, p = 0.054). Patients transported by HEMS had significantly higher survival compared with those transported by GEMS (92.5% for HEMS vs. 87.0% for GEMS, p = 0.002) in the 0-60-min time interval from dispatch to arrival to hospital, and more specifically, in the 31-60-min interval (92.2% vs. 85.2%, p = 0.001). No difference in survival between the two groups was observed in the shortest (0-30 min) or in the extended prehospital time intervals (>60 min).

CONCLUSION: In adult patients with penetrating trauma, HEMS transport was associated with improved survival in a specific total prehospital time interval (31 to 60 min). This finding can help emergency medicine service administrators develop evidence-based HEMS dispatch criteria.