Thoracic aortic injury in motor vehicle crashes: the effect of impact direction, side of body struck, and seat belt use

BACKGROUND: Using in-depth, real-world motor vehicle crash data from the United States and the United Kingdom, we aimed to assess the incidence and risk factors associated with thoracic aorta injuries. METHODS: De-identified National Automotive Sampling System Crashworthiness Data System (U.S.) and Co-operative Crash Injury Study (U.K.) data formed the basis of this retrospective analysis. Logistic regression was used to assess the level of risk of thoracic aorta injury associated with impact direction, seat belt use and, given the asymmetry of the thoracic cavity, whether being struck toward the left side of the body was associated with increased risk in side-impact crashes. RESULTS: A total of 13,436 U.S. and 3,756 U.K. drivers and front seat passengers were analyzed. The incidence of thoracic aorta injury in the U.S. and U.K. samples was 1.5% (n = 197) and 1.9% (n = 70), respectively. The risk was higher for occupants seated on the side closest to the impact than for occupants involved in frontal impact crashes. This was the case irrespective of whether the force was applied toward the left (belted: relative risk [RR], 4.6; 95% confidence interval [CI], 2.9-7.1; p < 0.001) or the right side (belted: RR, 2.6; 95% CI, 1.4-5.1; p < 0.004) of the occupant's body. For occupants involved in side-impact crashes, there was no difference in the risk of thoracic aorta injury whether the impacting force was applied toward the left or toward the right side of the occupant's body. Seat belt use provided a protective benefit such that the risk of thoracic aorta injury among unbelted occupants was three times higher than among belted occupants (RR, 3.0; 95% CI, 2.2-4.3; p < 0.001); however, the benefit varied across impact direction. Thoracic aorta injuries were found to be associated with high impact severity, and being struck by a sports utility vehicle relative to a passenger vehicle (RR, 1.7; 95% CI, 1.2-2.3; p = 0.001). CONCLUSION: Aortic injuries have been conventionally associated with frontal impacts. However, emergency clinicians should be aware that occupants of side-impact crashes are at greater risk, particularly if the occupant was unbelted and involved in a crash of high impact severity.     

Kinematics of belted fatalities in frontal collisions: A new approach in deep studies of injury mechanisms

BACKGROUND: More than half of car crash fatalities are belted occupants, and the majority of these occur as a consequence of frontal crashes. In an earlier study of crash configuration characteristics, we have shown that 48% of fatalities occurred in frontal small overlap (SO) crashes in which less than 30% of the vehicle front was engaged. Only 23% of fatalities occurred in large overlap (LO) crashes engaging the drive train, similar to most barrier front crash testing procedures. The main purpose of this study was to analyze the characteristics of injury mechanisms and injuries in fatal SO and LO car crashes in Sweden. METHOD: Retrospective examination and analysis of 61 fatally injured occupants from 53 car crashes within a sample area covering 40% of the population of Sweden was conducted. RESULTS: A clear difference in injury mechanisms and injuries was found between SO and LO crashes. The major injury mechanisms in SO crashes are explained by an oblique torso movement and rotation toward the outboard side, which causes a high proportion of serious lateral chest and head injuries. In contrast, LO crashes were generally characterized by serious anterior chest injuries in elderly occupants (> or =60 years). CONCLUSION: Current government and consumer barrier crash test procedures are not designed to estimate the performance of cars and restraint systems for the type of crashes which caused the majority of occupant fatalities in this data set.     

Fatal blunt aortic injuries: a review of 242 autopsy cases

OBJECTIVE: To characterize fatal blunt aortic injury (BAI). METHODS: A retrospective chart review of 242 cases of fatal BAI in patients who underwent an autopsy at our institution between 1984 and 1997 was performed. Comparisons were made for statistical differences using the z-test. RESULTS: Two hundred forty-two cases of fatal BAI were reviewed, making this the largest BAI autopsy study to date. Mechanisms of BAI included driver/passenger in motor vehicle crash (MVC) (68%), pedestrian versus MVC (17%), and motorcycle crash (8%). When comparing the mechanisms in the time period 1984 to 1988 to the time period 1989 to 1997, only the pedestrian versus MVC mechanism was significantly different (12% vs. 23%, p < 0.05). MVC direction of impact included head-on (45%), lateral (35%), and complex (20%). Two thirds of the victims sustained head injuries, rib fractures, and/or hepatic trauma. Only 58% of the victims had the classic isthmus laceration. There was one preventable death secondary to delay in diagnosis. CONCLUSION: BAI is not limited to frontal impact crashes; there should be a high index of suspicion of BAI in lateral impact crashes as well as pedestrian versus MVC mechanisms. Nonisthmus and complex aortic lacerations are common in fatal BAI. Finally, BAI is a highly lethal injury with few preventable deaths in this series.     

The spectrum of abdominal injuries associated with the use of seat belts

Several recent reports have described abdominal injuries occurring as a result of seat belt use, raising concerns about seat belts as an agent of injury in motor vehicle crashes. The purpose of this study was to characterize the distribution of abdominal injuries after motor vehicle crashes in belted and unbelted patients admitted to trauma centers. The mortality was higher in unbelted than belted patients (7% vs. 3.2%, respectively, p less than 0.0001). Unbelted patients also had significantly more frequent and more severe head injuries (50.0% vs. 32.9%, respectively, p less than 0.001). The incidence of abdominal injury was equal in both unbelted patients (13.9%), but the spectrum of organs injured was different in the two groups. Gastrointestinal tract injuries (stomach, small bowel, colon and rectum) were significantly more frequent in belted vs. unbelted patients (3.4% vs. 1.8%, respectively, p = 0.001). The frequency of liver and spleen injuries was the same in both groups. This study demonstrates that in patients admitted to trauma centers after motor vehicle crashes, belted and unbelted patients have an equal incidence of abdominal injury, but belted and unbelted patients have a different spectrum of injuries. Hollow viscus injuries are more common in belted crash victims. Seat belt use was associated with significantly fewer head injuries and deaths. Physicians evaluating trauma victims after motor vehicle crashes should be aware of the fact that the types of abdominal injuries may vary substantially depending on seat belt use.     

Risk factors associated with pelvic fractures sustained in motor vehicle collisions involving newer vehicles

BACKGROUND: Despite advances in automotive safety, pelvic fractures caused by motor vehicle collisions remain a significant cause of mortality, morbidity, and functional disability. This study was designed to evaluate epidemiologic and biomechanic risk factors associated with pelvic fractures resulting from motor vehicle collisions. We utilized the Crash Injury Research Engineering Network (CIREN) database to identify these risk factors in newer vehicles. METHODS: Data were prospectively collected at the ten CIREN centers from 1996 to 2005. Specific data were then abstracted on all patients, biomechanic crash characteristics, and injuries sustained. Patients involved in a frontal or near-side lateral impact with pelvic fractures were compared with those without. Univariate analysis was performed using a chi2 analysis. Logistic regression was used to identify significant risk factors in a multivariate analysis to control for confounding associations. RESULTS: Of the 1,851 patients studied, 511 (27.6%) had a pelvic fracture. The overall mortality was 17%. Injury specific factors associated with pelvic fracture were higher Injury Severity Score (ISS) and fatality of the patient. Biomechanic factors associated with the risk of pelvic fracture included; no airbag deployment (p < 0.001), smaller vehicle (p = 0.05), and lateral deformation location (p < 0.001). When stratified by vehicle deformation location, logistic regression models revealed statically significant variables in a frontal impact which included; higher body mass index, higher ISS, large patient vehicle, no seatbelt use, and higher deltaV. For near-side lateral impacts, multivariate analysis revealed statistically significant variables of lower body mass index, higher ISS, female sex, small vehicle size, and higher deltaV. CONCLUSIONS: Even in newer vehicles with federally mandated safety features, pelvic fractures remain a common injury. Pelvic fractures may serve as a marker of crash severity and specific crash characteristics are associated with pelvic fractures. Lateral crashes are significantly more likely to result in a pelvic fracture and, therefore, prevention of pelvic fractures should focus on improving occupant safety in near-side lateral impacts. Recognition of other associations should lead researchers to further investigate causative factors that will ultimately result in improved vehicle design.     

Pelvic ring fractures: implications of vehicle design, crash type, and occupant characteristics

BACKGROUND: Pelvic ring fractures (PRFs) are a major cause of morbidity and mortality in motor vehicle collisions (MVCs). Understanding the factors leading to PRFs may help improve vehicle design and safety. This study sought to determine the vehicular, crash, and occupant characteristics that contribute to PRFs. METHODS: From 1997 to 2003, 240 adult patients involved in lateral or frontal crashes were prospectively studied. Comprehensive crash reconstructions, vehicle analysis, and occupant data were compiled and analyzed as part of the national Crash Injury Research Engineering Network project. RESULTS: Of 240 study patients, 38 had PRFs. The incidence of PRFs was significantly associated with female gender, lateral impact crashes, vehicle incompatibility, and severity of crash. Seat belts and airbags were not protective against PRFs in either lateral or frontal crashes. CONCLUSIONS: All vehicles in the current study were less than 6 years old at the time of the MVC and thus reflect newer safety designs. Compared with studies of PRFs in MVCs before the widespread adoption of modern safety standards, our series suggests there has been a modest decrease in the incidence of PRFs in newer vehicles. Current safety standards do not adequately protect against PRFs, especially in lateral MVCs involving incompatibility and female occupants. New technology needs to be developed and implemented. Our data suggest that side impact airbags, alteration of vehicle geometry, and increased reinforcement of side panels and doors may result in fewer PRFs.     

Upper extremity fracture patterns following motor vehicle crashes differ for drivers and passengers

PURPOSE: Injury patterns of occupants in motor vehicle crashes are changing, with upper extremity injury becoming more common in patients treated at trauma centres. Although not life threatening, upper extremity injuries may result in long-term disability, including chronic deformity, neurovascular compromise and degenerative arthritis. The purpose of this study was to compare upper extremity injury in drivers and passengers using the Crash Injury Research Engineering Network (CIREN) database. METHODS: CIREN data were used to compare upper extremity skeletal injury patterns and sources for drivers and passengers in frontal and side impacts. Occupant variables (age, gender, co-morbidity, avoidance maneuvers and restraint use) and crash variables (direction of impact, delta V and vehicle crush) were considered in the analysis. RESULTS: Only 24.8% of all occupants in the CIREN database had upper extremity injuries. One-half of upper extremity injuries to drivers were forearm fractures compared to one-third for passengers. Occupants in side impacts were more likely (OR=5.05) to have clavicle fractures, even while controlling for driver versus passenger status and safety belt use. Air bags were more likely to be a source of forearm fracture (OR=2.31) when controlling for driver versus passenger status, direction of force, sex and age compared to other sources. Only 10% of driver fractures with air bag deployment in frontal impacts were associated with air bag fling. CONCLUSIONS: This study found that drivers and passengers have different upper extremity injury patterns but the direction of impact also plays an important role.     

Factors influencing pediatric Injury Severity Score and Glasgow Coma Scale in pediatric automobile crashes: results from the Crash Injury Research Engineering Network

Background/Purpose

Motor vehicle crashes account for more than 50% of pediatric injuries. Triage of pediatric patients to appropriate centers can be based on the crash/injury characteristics. Pediatric motor vehicle crash/injury characteristics can be determined from an in vitro laboratory using child crash dummies. However, to date, no detailed data with respect to outcomes and crash mechanism have been presented with a pediatric in vivo model.

Methods

The Crash Injury Research Engineering Network is comprised of 10 level 1 trauma centers. Crashes were examined with regard to age, crash severity (ΔV), crash direction, restraint use, and airbag deployment. Multiple logistic regression analysis was performed with Injury Severity Score (ISS) and Glasgow Coma Scale (GCS) as outcomes. Standard age groupings (0-4, 5-9, 10-14, and 15-18) were used. The database is biases toward a survivor population with few fatalities.

Results

Four hundred sixty-one motor vehicle crashes with 2500 injuries were analyzed (242 boys, 219 girls). Irrespective of age, ΔV > 30 mph resulted in increased ISS and decreased GCS (eg, for 0-4 years, ΔV < 30: ISS = 10, GCS = 13.5 vs ΔV > 30: ISS = 19.5, GCS = 10.6; P < .007, < .002, respectively). Controlling for ΔV, children in lateral crashes had increased ISS and decreased GCS versus those in frontal crashes. Airbag deployment was protective for children 15 to 18 years old and resulted in a lower ISS and higher GCS (odds ratio, 2.1; 95% confidence interval, 0.9-4.6). Front-seat passengers suffered more severe (ISS > 15) injuries than did backseat passengers (odds ratio, 1.7; 95% confidence interval, 0.7-3.4). A trend was noted for children younger than 12 years sitting in the front seat to have increased ISS and decreased GCS with airbag deployment but was limited by case number.

Conclusion

A reproducible pattern of increased ISS and lower GCS characterized by high severity, lateral crashes in children was noted. Further analysis of the specific injuries as a function and the crash characteristic can help guide management and prevention strategies.     

Change in velocity and energy dissipation on impact in motor vehicle crashes as a function of the direction of crash: key factors in the production of thoracic aortic injuries, their pattern of associated injuries and patient survival. A Crash Injury Research Engineering Network (CIREN) study

OBJECTIVE: To examine the effect of change in velocity (MV) and energy dissipation (IE) on impact, above and below the test levels for federal motor vehicle crash (MVC) safety standards, on the incidence of aortic injury (AI) and its mortality and associated injury patterns in frontal (F) and lateral (L) MVCs. Comparison of 80 AI and 796 non-AI patients of AIS=3. METHODS: Eight hundred seventy-six MVC adult drivers or front-seat passengers (552 F and 324 L) evaluated by 10 Level I CIREN study Trauma Centers together with vehicle and crash scene engineering reconstruction. Patient seatbelt and/or airbag use correlated with clinical or autopsy findings. RESULTS: In AI, 63% of cases were dead at the scene and only 16% survived to leave hospital. The relation between IE dissipated in the MVC and the DeltaV on impact was exponential as DeltaV increased, but the rise in IE for a given DeltaV was greater in LMVC than in FMVC (p <0.05). A more rapid rise in IE/DeltaV occurred above the mean DeltaV of 48 +/- 19.7 kph (30 mph) in FMVC and above the mean DeltaV of 36 +/- 16.2 kph (23 mph) in LMVC. As DeltaV increased above these means, 65% of 46 FMVC aortic injuries (AIs) and 64% of 34 LMVC AIs occurred. In AI patients there was evidence of focusing of the point of IE impact on the upper chest with a higher incidence of rib1-4 fractures than in non-AI (p <0.01) and more brain, heart, lung and spleen injuries (p <0.01) consequent to lower seatbelt use (p <0.01), but LMVC also had more pelvic fx (p <0.05). Airbags + seatbelts in FMVC and seatbelts in LMVC reduced mortality (p <0.05) Comparison of AI incidence in three successive 4-year vehicle model year periods showed a progressive decrease as new safety devices were introduced (p < 0.05). CONCLUSIONS: The implications for AI of the focused IE at the upper chest suggest a probable mechanism for MVC AI with the pressurized aortic arch acting as the long arm of a lever system with the fulcrum at the subclavian artery, producing maximum torsional strain at the short arm of the isthmus where 75% of the AIs occurred. AI mortality is also influenced by the associated injuries. To develop more effective safety systems to prevent AI, MVC safety testing with airbags and seatbelts should be carried out at DeltaVs of 1 SD above means for FMVC and LMVC.     

Human body tolerance to high energy trauma: influence of subcutaneous and visceral fat

Every year in the US, over 40,000 individuals are killed and more than 3 million others injured as a result of motor vehicle collisions (MVCs). The economic cost of crash injuries each year is greater than $230 billion. In order to improve vehicle safety, a better understanding of the mechanism by which injuries are caused in current crashes as well as the human factors that affect injury tolerance is required. Biomechanical studies using cadavers suggest that factors such as bone density, muscle mass and body geometry influence the body’s ability to tolerate injurious forces. We hypothesized that fat in both the subcutaneous and visceral compartments may act as an energy absorbing material and affect injury patterns in MVCs. This study examined the relationship between the severity of the injuries sustained in MVCs and that occupant’s subcutaneous and visceral fat volumes as measured by CT. 139 adults MVC occupants were studied. Field and vehicle inspection was performed to determine crash configuration, crash severity and restraint use. All of the patients received CT evaluation of their abdomen and pelvis as part of their trauma workup. A three-dimensional image of the abdomen was reconstructed and volumetric measurement of both the subcutaneous and visceral fat were performed on a two-inch slab at the level of the third lumbar vertebra. The results showed that increased volume of either subcutaneous or visceral fat correlated with a significant decrease in the overall Injury Severity Score (ISS) (p < 0.02). Increased subcutaneous fat was associated with significantly decreased injury severity to the head (p = 0.001) and abdominal (p = 0.02) regions, but significantly worse injury severity to the lower extremities (p < 0.0001). Subcutaneous fat volume was found to have greater influence on injury severity than occupant age, restraint status or crash severity.     

Patterns of maxillofacial injuries in restrained and unrestrained motor vehicle crash victims

Safety belts reduce the frequency and severity of injuries sustained in motor vehicle crashes. Since the head and face are the most frequently injured anatomic regions in motor vehicle crash victims, the use of active restraints should lessen these injuries. This study was undertaken to examine the ability of safety belts to prevent and alter the pattern of maxillofacial injuries. During a 6-month period beginning February 1, 1987, 613 motor vehicle crash victims presented alive to the Trauma Center at the University of Tennessee Medical Center at Knoxville and were entered into this study. There were 254 restrained victims (R), 290 unrestrained (UR), and 69 who were excluded for lack of sufficient data regarding restraint usage. Unrestrained victims tended to be younger (mean age: UR = 27.9, R = 31.7; p less than 0.03), and more often male (UR = 65% vs. R = 51%; p less than 0.03). Irrespective of position within the vehicle, the mean number of facial lacerations per person was less in the restrained group (R = 0.31, UR = 0.76; p less than 0.03). This injury reduction was more pronounced in front seat occupants (R = 0.27, UR = 0.82; p less than 0.03). Furthermore, a smaller proportion of the lacerations in the restrained group were categorized as complex, i.e., involving more than skin and subcutaneous tissue (R = 5.0%, UR = 15.9%; p less than 0.03). The pattern of skeletal injuries was also significantly different.(ABSTRACT TRUNCATED AT 250 WORDS)     

Seat belt use before and after motor vehicle trauma

BACKGROUND: Motor vehicle crashes cause significant morbidity and mortality annually. Seat belt use has partially been associated with a decreased risk of morbidity and mortality among those involved in motor vehicle crashes. Persons injured in motor vehicle crashes and not wearing seat belts have an increased risk of admission to trauma centers for motor vehicle crash-related injury. The purpose of this study was to measure changes in seat belt use after discharge among patients admitted to a Level I trauma center for injuries sustained in motor vehicle crashes. METHODS: Patients admitted to a Level I trauma center for injuries sustained in motor vehicle crashes during 1998 were eligible for participation. A telephone interview was conducted with a random sample of 136 eligible patients regarding patterns of seat belt use before and after their collision. Demographic data and clinical characteristics were also collected. The frequency of seat belt use before and after crash involvement was compared for all patients and stratified by age, gender, race, and Injury Severity Score (ISS). RESULTS: Slightly over half (54%) of patients reported "always" wearing a seat belt before their collision compared with 85% afterward. Younger age groups, male subjects, and whites had the largest increases in the frequency of seat belt use after collision (45%, 37%, and 44% increases, respectively). With respect to injury severity, the largest increase in the frequency of seat belt use was among those with ISS of 15 to 25 (82% increase). Significant concordance between patient- and emergency medical service-reported use of seat belts was observed. Among subjects reported by emergency medical service personnel to have been restrained, nearly 90% reported belt use at the time of the telephone interview. The most frequently cited occasion for failure to use seat belts (30%) was when taking short trips. Other reported reasons were forgetting to fasten belts (29%), discomfort (10%), being in a rush (8%), riding in the back seat (4%), and that seat belts were unnecessary when riding with a good driver (3%). CONCLUSION: Involvement in a motor vehicle crash results in increased seat belt use. Prevention efforts should be directed toward those patients who report infrequent use. Patient "converts" to seat belt use after collisions may be useful in public awareness and prevention campaigns.     

Seat belts are more effective than airbags in reducing thoracic aortic injury in frontal motor vehicle crashes

BACKGROUND: Airbags reduce the probability of death in frontal collisions, but the effect is small compared with seat belts. Little is known about the influence of seat belts and airbags on the incidence of thoracic aortic injury (TAI). METHODS: The National Automotive Sampling System database was queried for the years 1993 to 1998 to determine the impact of seat belts and airbags on the incidence of TAI in survivors of frontal motor vehicle crashes. Proportions were compared using the two-sample Z test. RESULTS: Seat belts prevent TAI regardless of airbag deployment. The effect of airbags is limited to those wearing seat belts. In frontal collisions without seat belt use, airbag deployment does not alter TAI incidence. CONCLUSION: Seat belts are considerably more effective in preventing TAI than airbags after frontal motor vehicle crashes. Prevention efforts should continue to emphasize the use of active restraints. Restraint use should be considered a risk factor in evaluating patients for potential TAI.     

Factors influencing the patterns of injuries and outcomes in car versus car crashes compared to sport utility, van, or pick-up truck versus car crashes: Crash Injury Research Engineering Network Study.

BACKGROUND: Data using crash dummies suggest that motor vehicle crashes (MVCs) involving passenger sedans (S) vs sport utility, vans, or light trucks (SUVTs) produce more severe injuries than those involving two sedans (SvS). However, no detailed data regarding pattern of injuries or force mechanisms involved have been presented in real patients. METHODS: The relationship of injury patterns and severities with MVC reconstruction data were obtained in 412 MVC patients, drivers or front seat passengers. Crashes were examined with regard to impact direction, frontal (F) or lateral (L) crashes, vehicle mass ratio, ISS, DELTA V, seat belt use, and airbag deployment (AB). RESULTS: In 309 F-MVC, AB reduced overall ISS (24.3 to 17.9) with a reduction in the mean severity of traumatic brain injury (TBI) GCS < or = 12, from 48% to only 28%. This AB protection from TBI was preserved as DELTA V increased to > 30 mph even though non-AB protected body areas (thorax, lung, liver, and lower extremity injuries) all increased. When vehicles of incompatible size and mass (SUVT) had F-MVC with sedans the incidence of severe TBI rose as did face lacerations despite AB or belt use. In L-MVC between SUVT and sedans compared with SvS MVC, there was a cephalad shift in body injuries with increased thorax, but decreased lower extremity injuries. The incidence of TBI increased. Analysis of injury contact sites (hits) showed more hits and a wider distribution of contract sites in SUVT vs sedan MVC. These appeared due to the greater mass excess and larger mass ratio, hood height, and width in the F-SUVT vs S crashes. All of these factors plus the increased bumper height above the body frame side-door sill were injury causal factors in the L-SUVT vs S MVCs. CONCLUSION: Both F and L crashes between sedans and SUVT with a high mass ratio shift the pattern of injury cephalad with increased thorax and intrathoracic organ injuries, and more severe TBI. These data suggest that improved head and thorax side-impact buffering and design features which transmit MVC forces from the higher front end of the larger mass SUVT to the frame of the sedan may better protect sedan occupants from side-impacts.     

Delta V as a predictor of significant injury for children involved in frontal motor vehicle crashes

OBJECTIVE: The objective of this study was to examine the association between delta V and risk of injury to children involved in frontal motor vehicle crashes. BACKGROUND: Previous studies, primarily focused on adult occupants, have demonstrated the relationship between crash severity, as measured by delta V and injury severity. As children have unique safety needs, these results cannot be directly applied to the pediatric population. METHODS: Case series crash investigation data and clinical injury information were reviewed from a child-focused crash surveillance system. Analyses were performed examining the relationship between the estimated delta V and any AIS > or = 2 or any AIS > or = 3 injury. RESULTS: Detailed crash investigation and clinical data were available on 407 children involved in 235 frontal crashes. The average delta V for all crashes was 29 +/- 16.9 kph [18 +/- 10.5 mph (range, 5-123 kph)]. Delta V was strongly and positively associated with the odds of both an AIS > or = 2 and AIS > or = 3 injury (P < 0.0001). The adjusted odds of at least one AIS > or = 2 injury increased on average by 56% (95% confidence interval [CI], 33%-85%) for each 10 kph increase in delta V. Similarly, the adjusted odds of at least one AIS > or = 3 injury increased on average by 67% (95% CI, 40%-102%) for each 10 kph increase in delta V. The delta V at which 50% of child occupants would be expected to sustain any AIS > or = 2 injury was 37 kph [23.0 mph (95% CI, 32-45 kph)], and any AIS > or = 3 injury was 63 kph [39.1 mph (95% CI, 51-infinity kph)]. CONCLUSION: Delta V is strongly predictive of injury risk for child occupants. As many newer generation cars are now fitted with event data recorders, this information is increasingly available and may become useful as a clinical predictor.     

Organ injuries associated with femoral fractures: implications for severity of injury in motor vehicle collisions

OBJECTIVE: To determine if motor vehicle collisions (MVCs) resulting in femoral fractures were associated with a different injury severity and pattern of injury compared with crashes in which victims did not sustain femoral fractures. METHODS: Retrospective review of seriously injured motor vehicle occupants admitted to a regional trauma unit (Hamilton General Hospital) during a 69-month period (April 1991 to December 1996) for whom detailed crash details were known. RESULTS: Data for 733 motor vehicle occupants with Injury Severity Scores greater than 12 were available; 112 occupants (15.3%) sustained femoral fractures, and 621 occupants (84.7%) did not sustain femoral fractures. Victims with femoral fractures had a significantly higher mean Injury Severity Score (29.4 compared with 25.3 for non-femoral fracture group; p<0.001). The femoral fracture group had a higher incidence of bowel (p<0.012) and hemopneumothorax (p<0.02) injuries as well as an increased incidence of upper and lower extremity (p<0.001) and pelvic (p<0.05) fractures. CONCLUSION: The presence of a femoral fracture is strongly associated with the pattern and severity of injuries sustained by occupants in MVCs. A high index of suspicion is warranted in identifying associated organ injuries in MVC victims with concomitant femoral fractures.     

Aggressive traffic enforcement: a simple and effective injury prevention program

PURPOSE: To investigate whether an aggressive traffic violation enforcement program could reduce motor vehicle crashes (MVCs), injury collisions, fatalities, and fatalities related to speed, and decrease injury severity in crash victims treated at the trauma center. METHODS: A vigorous enforcement program was established within Fresno, Calif, city boundaries using increased traffic patrol officers. Data on citations, collisions, fatal collisions, and fatalities related to speed, as well as injury severity from the trauma registry, were collected for the year before program onset (2002), during the first year (2003), and after full implementation (2004). U.S. Census Bureau information was used for population. Statistical analysis was performed using Fisher's exact test and independent samples t test with significance attributed to p < 0.05. RESULTS: There were significant increases in citations issued, with marked decreases in motor vehicle crashes, injury collisions, fatalities, and fatalities related to speed. There was a decrease in admissions from MVCs, a significant decrease in the number of patients with moderate injury severity (Injury Severity Score of 10-16; p < 0.01), a decrease in hospital length of stay for all MVC victims, and a decrease in hospital charges for MVC patients. These changes were not seen in the area of Fresno County outside the area of increased enforcement. CONCLUSIONS: Aggressive traffic enforcement decreased MVCs, crash fatalities, and fatalities related to speed, and it decreased injury severity. This is a simple, easily implemented injury prevention program with immediate benefit.     

Risk factors for blunt thoracic aortic injury in children

Background/Purpose

Because blunt thoracic aortic injury is rare in children, a high index of suspicion is needed to identify this injury. The purpose of this study was to use a large national trauma database to define the risk factors for blunt thoracic aortic injury in children.

Methods

Using the National Trauma Database, the authors compared patient demographics, mechanism of injury, and associated injuries between children sustaining blunt trauma with and without a thoracic aortic injury. Factors independently associated with this injury were identified using multivariate methods.

Results

Among 26,940 children with a blunt mechanism of injury, 34 (0.1%) children sustained a thoracic aortic injury, 14 (41%) of whom died. Thoracic aortic injuries were independently associated with age, injury sustained as an occupant in a motor vehicle crash, and severe injuries (Abbreviated Injury Scale value of ≥3) involving the head, thorax (other than aorta), abdomen, and lower extremities.

Conclusions

Older children involved in a motor vehicle crash with severe head, torso, and lower extremity injuries are a group at high risk for injury to the thoracic aorta. These easily identifiable risk factors may facilitate more rapid identification of this rare and potentially fatal injury.     

The new car assessment program: does it predict the relative safety of vehicles in actual crashes?

BACKGROUND: Federal motor vehicle safety standards are based on crash test dummy analyses that estimate the relative risk of traumatic brain injury (TBI) and severe thoracic injury (STI) by quantifying head (Head Injury Criterion [HIC]) and chest (Chest Gravity Score [CGS]) acceleration. The New Car Assessment Program (NCAP) combines these probabilities to yield the vehicle's five-star rating. The validity of the NCAP system as it relates to an actual motor vehicle crash (MVC) remains undetermined. We therefore sought to determine whether HIC and CGS accurately predict TBI and STI in actual crashes, and compared the NCAP five-star rating system to the rates of TBI and/or STI in actual MVCs. METHODS: We analyzed frontal crashes with restrained drivers from the 1994 to 1998 National Automotive Sampling System. The relationship of HIC and CGS to the probabilities of TBI and STI derived from crash tests were respectively compared with the HIC-TBI and CGS-STI risk relationships observed in actual crashes while controlling for covariates. Receiver operating characteristic curves determined the sensitivity and specificity of HIC and CGS as predictors of TBI and STI, respectively. Estimates of the likelihood of TBI and/or STI (in actual MVCs) were compared with the expected probabilities of TBI and STI (determined by crash test analysis), as they relate to NCAP ratings. RESULTS: The crash tests overestimate TBI likelihood at HIC scores >800 and underestimate it at scores <500. STI likelihood is overestimated when CGS exceeds 40 g. Receiver operating characteristic curves demonstrated poor sensitivity and specificity of HIC and CGS in predicting injury. The actual MVC injury probability estimates did not vary between vehicles of different NCAP rating. CONCLUSION: HIC and CGS are poor predictors of TBI and STI in actual MVCs. The NCAP five-star rating system is unable to differentiate vehicles of varying crashworthiness in actual MVCs. More sensitive parameters need to be developed and incorporated into vehicle crash safety testing to provide consumers and automotive manufacturers with useful tools with which to measure vehicle safety.     

Pelvic fractures: epidemiology and predictors of associated abdominal injuries and outcomes

BACKGROUND: Pelvic fractures are often associated with major intraabdominal injuries or severe bleeding from the fracture site. OBJECTIVE: To study the epidemiology of pelvic fractures and identify important risk factors for associated abdominal injuries, bleeding, need for angiographic embolization, and death. METHODS: Trauma registry study on pelvic fractures from blunt trauma. Stepwise logistic regression was used to identify risk factors of severe pelvic fractures, associated abdominal injuries, need for major blood transfusion, therapeutic embolization, and death from pelvic fracture. Adjusted relative risks and 95% confidence intervals were derived. RESULTS: There were 16,630 trauma registry patients with blunt trauma, of whom 1,545 (9.3%) had a pelvic fracture. The incidence of abdominal injuries was 16.5%, and the most common injured organs were the liver (6.1%) and the bladder and urethra (5.8%). In severe pelvic fractures (Abbreviated Injury Scale [AIS] > or =4), the incidence of associated intraabdominal injuries was 30.7%, and the most commonly injured organs were the bladder and urethra (14.6%). Among the risk factors studied, motor vehicle crash is the only notable risk factor negatively associated with severe pelvic fracture. Major risk factors for associated liver injury were motor vehicle crash and pelvis AIS > or = 4. Risk factors of major blood loss were age > 16 years, pelvic AIS > or =4, angiographic embolization, and Injury Severity Score (ISS) > 25. Age> 55 years was the only predictor for associated aortic injury. Factors associated with therapeutic angiographic embolization were pelvic AIS > or =4 and ISS > 25. The overall mortality was 13.5%, but only 0.8% died as a direct result of pelvic fracture. The only pronounced risk factor associated with mortality was ISS>25. CONCLUSIONS: Some epidemiological variables are important risk factors of severity of pelvic fractures, presence of associated abdominal injuries, blood loss, and need of angiography. These risk factors can help in selecting the most appropriate diagnostic and therapeutic interventions.