- Significance: Approximately 1.4 million victims of Traumatic Brain Injury (TBI) are seen in emergency departments each year in the U.S. and, of those, 50,000 die and 235,000 are hospitalized. A least 2% of the U.S. population has a TBI-related long-term need for help to perform activities of daily living. There is growing evidence that the management of TBI in the early minutes after injury profoundly impacts outcome. This has led to the promulgation of evidence-based TBI treatment guidelines by authoritative national and international scientific bodies. Reports on guideline implementation in the hospital setting are very promising. However, no studies have evaluated their impact in the prehospital setting. While randomized prehospital trials to identify the effectiveness of the guidelines would clearly be optimal, the strong indirect evidence currently precludes withholding guideline therapy because of ethical considerations. Thus a large, prospective, historically controlled, observational study is the best methodology currently available to evaluate the effectiveness of implementing the guidelines in the prehospital setting.