Effect of weight, height and BMI on injury outcome in side impact crashes without airbag deployment

A First Step Toward a Family of Morphed Human Body Models Enabling Prediction of Population Injury Outcomes

The injury risk in a vehicle crash can depend on occupant specific factors. Virtual crash testing using finite element human body models (HBMs) to represent occupant variability can enable the development of vehicles with improved safety for all occupants. In this study, it was investigated how many HBMs of different sizes that are needed to represent a population crash outcome through a metamodel. Rib fracture risk was used as an example occupant injury outcome. Morphed HBMs representing variability in sex, height, and weight within defined population ranges were used to calculate population variability in rib fracture risk in a frontal and a side crash. Two regression methods, regularized linear regression with second-order terms and Gaussian process regression (GPR), were used to metamodel rib fracture risk due to occupant variability. By studying metamodel predictive performance as a function of training data, it was found that constructing GPR metamodels using 25 individuals of each sex appears sufficient to model the population rib fracture risk outcome in a general crash scenario. Further, by utilizing the known outcomes in the two crashes, an optimization method selected individuals representative for population outcomes across both crash scenarios. The optimization results showed that 5-7 individuals of each sex were sufficient to create predictive GPR metamodels. The optimization method can be extended for more crashes and vehicles, which can be used to identify a family of HBMs that are generally representative of population injury outcomes in future work.

The Association of Body Mass Index and Outcomes in Adult Patients with Chest Wall Injuries

BACKGROUND

Thoracic injury secondary to rib fractures following motor vehicle collisions (MVCs) significantly contribute to morbidity and mortality. While obesity has reached epidemic proportions, little is known regarding how BMI impacts outcomes in MVCs. The aim of this study was to examine how BMI impacts outcomes in MVC patients with rib fractures.

METHODS

The ACS-TQIP Database was utilized to evaluate adult MVC patients with ≥3 rib fractures. Patients with a non-thoracic AIS ≥3 were excluded, to focus on chest injuries. Patients were sorted according to the presence or absence of flail chest injuries and BMI into groups with a low (<15), intermediate (15-24), or severe (≥25) ISS.

RESULTS

Overweight and obese patients in the non-flail cohort had decreased odds of pneumothorax in all ISS groups (P < 0.05). Overweight (P = 0.049) and obese (P = 0.011) patients in the low ISS non-flail cohort had decreased odds of splenic laceration. In the non-flail cohort, obese patients with a low and intermediate ISS had decreased odds of pulmonary contusion (P < 0.01). Obese patients in the low and intermediate ISS non-flail cohorts had increased odds of PE (P < 0.05). In both the flail and non-flail cohorts, obese patients with an intermediate ISS had decreased odds of liver laceration (P < 0.05), as well as a longer HLOS, ICU-LOS, and mechanical ventilation time (P < 0.01).

CONCLUSION

Obesity affects associated injuries, complications, and hospital outcomes in a complex way after MVC related chest wall trauma. Thus, the effect of BMI should be taken into consideration when assessing and treating obese MVC trauma patients.

The Effects of Body Mass Index and Seatbelt Use on Pediatric Chest and Abdominal Injuries after Motor Vehicle Collisions

BACKGROUND

Motor vehicle collisions (MVCs) are a major cause of pediatric morbidity and mortality. However, the effect of body mass index (BMI) and seatbelt use on thoracic injuries and outcomes in pediatric patients with rib fractures remains unexplored. We aim to assess how seatbelt use and BMI affect thoracic injuries and outcomes in pediatric patients who sustained ≥3 rib fractures following an MVC.

METHODS

The Trauma Quality Improvement Program (TQIP) database (2013-2017) was queried for pediatric patients (8-17 years and >4 feet 9 inches tall) admitted secondary to MVCs, with ≥3 rib fractures and all non-thoracic Abbreviated Injury Scale ≤2. Patients were then divided by Injury Severity Score (ISS) into low (<15) and intermediate-severe (≥15) groups, which were further subdivided according to seatbelt use and BMI. Logistic and linear regression was performed to assess the effects of seatbelt use and BMI on outcomes.

RESULTS

Seatbelt compliance varied from 39.6 to 50.7%. Belted patients (intermediate-severe ISS) had a reduced hospital length of stay (HLOS), intensive care unit length of stay(ICU-LOS), and mechanical ventilation time but had increased odds of splenic laceration vs. unbelted patients (aOR = 2.46, 95% CI: 1.03-5.93, P = .044). Obese patients (low ISS) had lower incidences of hemothorax, pneumothorax, pulmonary contusion, splenic laceration, and liver injury compared to normal-weight patients. Overweight patients (intermediate-severe ISS) had a significantly reduced ICU-LOS vs. normal-weight patients (β = -.17, 95% CI: -.33,-.01, = .041).

CONCLUSIONS

Seatbelt use may improve outcomes for pediatric MVC patients with ≥3 rib fractures. Higher BMI may be associated with reduced thoracic injury and decreased ICU-LOS. Effective educational initiatives are needed to increase pediatric seatbelt compliance.

Do NHTSA vehicle safety ratings affect side impact crash outcomes?

INTRODUCTION

Side impact crash injuries tend to be severe, mainly due to the effects of the mechanism of such crashes. This study addresses the relationship between side impact crash injury severities and side impact safety ratings of the passenger cars involved in such crashes. It is motivated by the lack of research on side impact safety ratings in relation to the real-world crash outcomes.

METHOD

Analysis of Crashworthiness Data System's (CDS) data show the head and thorax are the most common regions of impact of severe injuries, while the neck is the least. Irrespective of body regions, higher-rated vehicles were found to provide better occupant protection to both younger and older driver age groups. Assessment based on injury severity score (ISS) indicates that higher-rated vehicles have an overall lower average ISS compared to lower-rated vehicles.

RESULTS

Ultimately, this study shows that vehicles rated with National Highway Traffic Safety Administration's (NHTSA) new criteria had lower average ISS compared to vehicles rated under the old criteria. The 2011 NHTSA side impact rating criteria being relatively new, it has very few crashes to draw meaningful statistically significant conclusions. However, this paper establishes the fact that vehicles with higher star ratings (under experimental conditions) indeed offer increased occupant protection in the field conditions. Practical applications: Previous studies have found that safety was given priority while buying new vehicles. However, people associated vehicle safety with technologies and specific safety features rather than the vehicle's crash test results or ratings (Koppel, Charlton, Fildes, & Fitzharris, 2008). The results from this study provide a point of reference for safety advocates to educate the drivers about the importance of considering vehicle safety ratings during a vehicle purchase.

Concussion, Diffuse Axonal Injury, and AIS4+ Head Injury in Motor Vehicle Crashes

PURPOSE

This is a descriptive study of the annual incidence of brain injuries in motor vehicle crashes by type, seat belt use, and crash severity (delta V) using national accident data. The risk for concussion, diffuse axonal injury (DAI), and severe head injury was determined.

METHODS

1994-2011 NASS-CDS was analyzed to estimate the number of brain injuries annually in nonejected adults involved in motor vehicle crashes. Crashes were grouped by front, side, rear, and rollover, and the effect of belt use was investigated. Light vehicles were included with model year 1994+. Head injuries were identified as concussion, DAI, severe head injury (Abbreviated Injury Scale [AIS] 4+), and skull fracture. The annual incidence, risk, and rate for different types of head injury were estimated with standard errors.

RESULTS

Motor vehicle crashes involved 33,191 ± 7,815 occupants with concussion, 5,665 ± 996 with AIS 4+ head injuries, 986 ± 446 with DAI, and 3,300 ± 531 with skull fracture annually. The risk was 1.64 ± 0.39% for concussion, 0.28 ± 0.05% for severe head injury (AIS 4+), 0.05 ± 0.02% for DAI, and 0.16 ± 0.03% for skull fracture in tow-away crashes. The risk for severe head injury (AIS 4+) was highest in rollovers (0.74 ± 0.16%) and lowest in rear impacts (0.17 ± 0.05%). Head injury risk depended on seat belt use, crash type, and crash severity (delta V). Seat belt use lowered the risk for AIS 4+ head injury by 74.8% and skull fracture by 73.2%.

CONCLUSIONS

Concussions occur in about one out of 61 occupants in tow-away crashes. The risk was highest in rollover crashes (4.73 ± 1.09%) and it was reduced 69.2% by seat belt use. Severe brain injuries occurred less often and the risk was also reduced by seat belt use.