Splenic injury in side impact motor vehicle collisions: Effect of occupantrestraints

Background. Side impact motor vehicle collisions (MVCs) are associated with higher morbidity and mortality compared with other types of MVCs. The stif fness of the lateral aspect of the vehicle and restraint use may play a rol e. The purpose of this study was to evaluate the role of restraint use, veh icle size, and compartment intrusion on the incidence of splenic injury in side impact MVCs. Methods. The National Automotive Sampling System was used to identify drive rs involved in side impact collisions for the years 1996 to 1998. The incid ence of splenic injury in these collisions was compared according to restra int use, vehicle size, and magnitude of vehicle crush. Information on the p erceived cause of splenic injuries sustained in the MVC was also obtained f rom National Automotive Sampling System investigator records. Results. Overall, among drivers involved in side impact MVCs, restraint use was associated with a significantly reduced rate of mortality (odds ratio [OR], 0.40; p < 0.0001) and splenic injury (OR, 0.76; p < 0.0001). Restrain ed drivers of small vehicles (<2,500 lb), however, had a higher incidence o f splenic injury in both minimal (lateral intrusion < 30 cm) (OR, 60.1; p < 0.0001) and severe (lateral intrusion > 30 cm) (OR, 4.0; p < 0.0001) magni tudes of vehicle crush on the driver's side of the vehicle. For both midsiz e (2,500-3,000 lb) and large (>3,000 lb) vehicles, restraint use was associ ated with a lower risk of splenic injury regardless of the magnitude of cru sh. In nearly all cases of splenic injury, the left vehicle interior was th e source of injury. Conclusion: Overall, restraint use is associated with lower rates of spleni c injury and mortality in side impacts. Despite this fact, restrained drive rs of small vehicles have a higher risk of splenic injury after lateral imp act MVCs when compared with unrestrained drivers. Evaluation of the combine d role of restraint use, crash, and injury patterns may provide novel insig ht regarding vehicle safety design features.