BACKGROUND: There is ongoing controversy about the relative effectiveness of air medical versus ground transportation for severely injured patients. In some systems, air medical crews may provide a higher level of care but may require longer transport times. We sought to evaluate the impact of mode of transport on outcome based on analysis of data from two randomized trials of prehospital hypertonic resuscitation. METHODS: Injured patients were enrolled based on prehospital evidence of hypovolemic shock (systolic blood pressure ≥70 mm Hg or systolic blood pressure ≥ 71-90 mm Hg with heart rate ≥108 bpm) or severe traumatic brain injury (TBI; Glasgow Coma Scale score ≥8). Patient demographics, injury severity, and physiology were compared based on mode of transport. Multivariate logistic regression was used to determine the impact of mode of transport on 24-hour and 28-day survival for all patients and 6-month extended Glasgow Outcome Scale for patients with TBI, adjusting for differences in injury severity. RESULTS: Included were 2,049 patients, of which 703 (34%) were transported by air. Patients transported by air were more severely injured (mean Injury Severity Score, 30.3 vs. 22.8; p < 0.001), more likely to be in the TBI cohort (70% vs. 55.4%; p < 0.001), and more likely blunt mechanism (94.0% vs. 78.1%; p < 0.001). Patients transported by air had higher rates of prehospital intubation (81% vs. 36%; p < 0.001), received more intravenous fluids (mean 1.3 L vs. 0.8 L; p < 0.001), and had longer prehospital times (mean 76.1 minutes vs. 43.5 minutes; p < 0.001). Adjusted analysis revealed no significant impact of mode of transport on survival or 6-month neurologic outcome (air transport-28-day survival: odds ratio, 1.11; 95% confidence interval, 0.82-1.51; 6-month extended Glasgow Outcome Scale score ≤4: odds ratio, 0.94; 95% confidence interval, 0.68 -1.31). CONCLUSION: There was no difference in the adjusted clinical outcome according to mode of transport. However, air medical transported more severely injured patients with more advanced life support procedures and longer prehospital time. Copyright © 2012 by Lippincott Williams & Wilkins.