The applicability of a computer model for predicting head injury incurred during actual motor vehicle collisions.

BACKGROUND: Head injury is a significant cause of both morbidity and mortality. Motor vehicle collisions (MVCs) are the most common source of head injury in the United States. No studies have conclusively determined the applicability of computer models for accurate prediction of head injuries sustained in actual MVCs. This study sought to determine the applicability of such models for predicting head injuries sustained by MVC occupants. METHODS: The Crash Injury Research and Engineering Network (CIREN) database was queried for restrained drivers who sustained a head injury. These collisions were modeled using occupant dynamic modeling (MADYMO) software, and head injury scores were generated. The computer-generated head injury scores then were evaluated with respect to the actual head injuries sustained by the occupants to determine the applicability of MADYMO computer modeling for predicting head injury. RESULTS: Five occupants meeting the selection criteria for the study were selected from the CIREN database. The head injury scores generated by MADYMO were lower than expected given the actual injuries sustained. In only one case did the computer analysis predict a head injury of a severity similar to that actually sustained by the occupant. CONCLUSION: Although computer modeling accurately simulates experimental crash tests, it may not be applicable for predicting head injury in actual MVCs. Many complicating factors surrounding actual MVCs make accurate computer modeling difficult. Future modeling efforts should consider variables such as age of the occupant and should account for a wider variety of crash scenarios.

The evolution of chest computed tomography for the definitive diagnosis of blunt aortic injury: a single-center experience.

BACKGROUND: Chest computed tomography (CT) is an excellent screening tool for blunt aortic injuries (BAIs). Aortography is considered the "gold standard" for diagnosis. Recent evidence suggests that new-generation, multislice, helical CT technology can accurately diagnose BAI. METHODS: A retrospective review of aortograms performed to evaluate for BAI was compared with the results of CT and operative findings. BAIs definitively diagnosed by CT alone were also studied. RESULTS: Between July 1, 1996, and June 30, 2002, 113 aortograms were obtained, with 28 BAI cases confirmed. Of these, 27 were congruently diagnosed by CT. Only one computed tomographic scan diagnostic for BAI had a subsequent negative aortogram. Seventeen BAIs were diagnosed with CT alone. Ten were confirmed operatively and seven were treated nonoperatively because of age, comorbid conditions, severity of injury, or the presence of small intimal defects. CONCLUSION: CT technology has evolved to allow for the definitive diagnosis and treatment of BAI. Aortography should still be used where new-generation CT is not available.

Association between side air bags and risk of injury in motor vehicle collisions with near-side impact.

BACKGROUND: Side air bags (SABs) have been introduced in an attempt to reduce the risk of injury in near-side-impact motor vehicle collisions (MVCs). The impact of SABs on MVC-related mortality and morbidity has yet to be evaluated with a large population-based study. The objective of this study was to assess the effectiveness of SABs in reducing the risk of injury or death in near-side-impact MVCs. METHODS: A retrospective study investigated outboard front seat occupants involved in police-reported, near-side-impact MVCs using data from the General Estimates System (1997-2000). The risk of MVC-related nonfatal and fatal injury for occupants of vehicles with and without SABs was compared. RESULTS: Front seat occupants of vehicles with SABs had a risk of injury similar to that of occupants of vehicles without SABs (risk ratio [RR], 0.96; 95% CI confidence interval [CI], 0.79-1.15). Adjustment for the potentially confounding effects of age, gender, seat belt use, seating position, damage severity and location, and vehicle body type did not meaningfully affect the association (RR, 0.90; 95% CICI, 0.76-1.08). CONCLUSIONS: There is no association between the availability of SABs and overall injury risk in near-side-impact MVCs. Future research is necessary to determine the effectiveness of SABs in preventing the injuries for which they were specifically designed.

Occupant- and collision-related risk factors for blunt thoracic aorta injury.

BACKGROUND: Blunt thoracic aortic injury (BAI) is a rare and highly lethal injury. We sought to identify occupant and collision characteristics associated with motor vehicle collision (MVC)-related BAI. METHODS: The 1995 to 2000 National Automotive Sampling System data files were used. The National Automotive Sampling System is a national probability sample of passenger vehicles involved in police-reported tow-away MVCs. The risk of BAI was calculated according to specific occupant (e.g., age, seat belt use) and collision (e.g., delta-V [estimated change in velocity], vehicular intrusion) characteristics. The association between BAI and these characteristics was calculated using risk ratios (RRs) and associated 95% confidence intervals (CIs). RESULTS: Specific occupant and collision characteristics demonstrated independent association with BAI. Occupant characteristics included age >or= 60 (RR, 3.6; 95% CI, 2.5-5.2), seat belt use (RR, 0.3; 95% CI, 0.2-0.5), and being a front-seat occupant (RR, 3.1; 95% CI, 1.5-6.3). Frontal and near-side MVCs were associated with an increased risk (RR, 3.1; 95% CI, 1.9-5.1; and RR, 4.3; 95% CI, 2.6-7.2, respectively) relative to other collision types. Collisions with a delta-V >or= 40 km/h (RR, 3.8; 95% CI, 2.6-5.6) or that produce extensive vehicle crush (>or= 40 cm) (RR, 4.1; 95% CI, 2.7-6.3) or intrusion (>or= 15 cm) (RR, 5.0; 95% CI, 3.5-7.3) also increase the risk of BAI. CONCLUSION: The risk factors for BAI identified in this study support generally accepted etiologic mechanisms for this injury.

Relationship between age and lower extremity fractures in frontal motor vehicle collisions.

BACKGROUND: Older adults (aged > or = 65 years) represent the single fastest growing segment of the United States population and will comprise one in five Americans during the third decade of this century. As this population segment rapidly expands, lower extremity fractures (LE Fx) and their associated disability will become a greater public health concern. The purpose of this study was to quantify the risk for LE Fx from motor vehicle collisions (MVCs) according to age. METHODS: The 1995 to 2000 National Automotive Sampling System data files were used. Study entry was limited to front-seat occupants involved in frontal MVCs. Risk ratios for LE Fx and age were adjusted for gender, driver versus passenger, seat belt use, airbag deployment, delta-V, intrusion, and vehicle type. RESULTS: Beginning in the fourth decade, there was a trend of higher relative risk for LE Fx with age that reached statistical significance in the seventh decade of life. CONCLUSION: This study documented an increased risk of LE Fx in older MVC occupants. Efforts to prevent these disabling injuries and to better protect occupants' lower extremities in MVCs should include improved vehicle design and reevaluation of the existing federal motor vehicle safety standards.

Injury rates among restrained drivers in motor vehicle collisions: the role of body habitus.

BACKGROUND: Previous studies have examined the independent effects of occupant height, obesity, and body mass index in motor vehicle collisions and identified related injury patterns. The hypothesis of this study was that as the driver's body habitus diverges from the 50% percentile male Hybrid III Crash Dummy (H3CD), the frequency of injury changes. METHODS: The 1995 to 1999 National Automotive Sampling System Crashworthiness Data System was used. Study entry was limited to restrained drivers who were then subdivided into height and weight categories. Incidence rates were calculated for injuries to selected body regions as defined by the Abbreviated Injury Scale for overall, frontal, and driver's side collisions. RESULTS: When grouped according to height and weight as descriptors of body habitus, injury rates for restrained drivers were increased as well as decreased in several subgroups. This association was seen in overall, frontal, and driver's side collisions. CONCLUSION: The H3CD plays a major role in vehicular cabin interior design and crash testing. For drivers with a body habitus different from that of the H3CD, the vehicle cabin/body fit changes and the safety features may perform differently, which could account for these observations.

Incidence and characteristics of motor vehicle collision-related blunt thoracic aortic injury according to age.

BACKGROUND: Motor vehicle collision-related blunt thoracic aorta injury (BAI) is rare and highly lethal. Vascular disease as related to advancing age potentially subjects older adults to increased risk of BAI; the mechanisms associated with such injuries may be different as compared with younger adults. The goal of the present study is to test this hypothesis using population-based data. METHODS: The 1995 to 1999 National Automotive Sampling System data files were used. The National Automotive Sampling System is a national probability sample of passenger vehicles involved in police-reported tow-away crashes. BAI was defined according to the Abbreviated Injury Scale codes. Among those with BAI, information on occupant (age, seating position, restraint use), collision (collision type, delta-V, vehicle intrusion), and outcome characteristics were obtained and compared according to age. RESULTS: The overall incidence of BAI was 6.8 per 10,000 occupants and there was a steady increase in the BAI rate for advancing decades of life. The proportion of occupants with BAI who die at the scene of the collision is relatively consistent across all age groups ( approximately 85%). Among those who survive to receive medical care, ultimate survival is lowest among those aged 60 and older. Near-side collisions were responsible for more BAI among older adults than other age groups (50% vs. 20.6%, p < or = 0.05). Older adults sustained BAI in collisions with lower delta-V values compared with younger persons (p < or = 0.05). CONCLUSION: Older adults have the highest rate of motor vehicle collision-related BAI, and their injuries tend to occur in less severe collisions. A high level of suspicion for BAI among older adults should not be reserved for high-energy collisions only.