An analysis of Delta V and brain injury in motorsports crashes

Abstract

Study objectives: Traumatic brain injury is responsible for up to half of trauma deaths and accounts for most cases of permanent disability after injury. In the United States between 1989 and 1998, an annual average of 53,288 deaths was associated with traumatic brain injury, and 34% of these were a result of motor vehicle crashes. The investigation of crashes to understand factors of occupant injuries is an established practice. Investigations on Indy Car crashes provide many significant advantages (eg, well-defined population of drivers and structural design of cars, rapid emergency response, well-defined driver position and restraint use) in the accuracy and detail of data compared with a highway crash investigation. The goal of our research efforts is to improve the safety of automobile racing, with anticipation that many of our findings may be translated to passenger car safety improvements. To progress to this end, we are interested in estimating injury thresholds for Indy Racing League (IRL) crashes. In 1996, the IRL began prospectively collecting data on all racing crashes in the series, with the aim of improving safety through the application of crash-protection research. Our objective is to evaluate the association between change in velocity (ΔV) and brain injury occurrence. We also evaluated the relationship of ΔV and the severity of the brain injury. Methods: We performed an analysis of prospectively collected data about collisions on the IRL circuit. Data were collected from January 1996 to July 2003. An accident data recorder was mounted near the center of gravity of IRL cars during this period and measured crash-pulse data. The accident data recorder is a stand-alone, 3-axis, acceleration-sensing data recorder that retains data when acceleration exceeds a set threshold. The vehicle ΔV was measured and recorded for each crash. Driver injury data were abstracted by IRL nurses at the accident from physician diagnosis ( International Classification of Diseases, Ninth Revision, Clinical Modification discharge diagnosis code) at the track emergency center and any health care facility to which drivers were referred. The nurses also recorded the specifics of each injury, including the specific symptoms and the duration of these symptoms. We used the head-injury aspect of the Abbreviated Injury Scale (AIS) to evaluate the severity of brain injury. The AIS is a simple injury scale with values that represent a compromise between energy absorption by injury and threat-to-life criteria. Individual injuries are rated separately in addition to the overall rating that may be assigned. The median vehicle ΔV for those with a brain injury was compared with that for those without a brain injury using the Wilcoxon rank-sum test. For drivers who sustained a brain injury, the median ΔV was compared between those with an AIS 2+ or AIS 3+ injury and those with a lesser injury. Results: Crash data were available on 374 crashes, with the vehicle ΔV being recorded in 267 of these accidents. There were 28 brain injuries, with 21 of these being an AIS 2+ brain injury and 7 being an AIS 3+ brain injury. The median ΔV for drivers sustaining a brain injury was 60.5 (range 35 to 98) compared with 39 (range 4 to 165) for those with no brain injury ( P P =.770). For those with AIS 3+ brain injury, the median ΔV of 51 (range 36 to 90) was not different ( P =.633) from the median ΔV of 62 (range 35 to 98) in those with a less severe injury. Conclusion: The median vehicle change in velocity in IRL crashes resulting in brain injury is 60.5 and is associated with the occurrence of a brain injury. In those crashes in which a brain injury occurs, the vehicle ΔV is not predictive of the severity of the injury. Future investigations to decrease vehicle ΔV may decrease brain injuries in IRL and even highway crashes.