Driver and front seat passenger fatalities associated with air bag deployment. Part 1: A Canadian study

Real world motor vehicle collision research of injuries due to deployment of "first-generation" air bags has been conducted by Transport Canada since 1993. Fifty-three fatal crashes (36 frontal impacts; 17 side collisions) involving 48 drivers and 10 right front passengers were reviewed. In the Canadian data, air bag deployment in five of nine low severity frontal crashes (delta-V (deltaV) < 25 km/h or 15 mph) was linked to five deaths, four of whom were autopsied (four adults with craniocervical (basal skull and C2 fracture with brainstem avulsion; "closed head injury"--no autopsy) or chest trauma (aortic or pulmonary artery tears); one child with atlanto-occipital dislocation). An occupant who is close ("out-of-position") to the air bag at the time of deployment is at risk for injury. In 27 high severity frontal impacts, unusual (e.g., pulmonary "blast" hemorrhage in one autopsied case) or isolated potentially survivable injuries (e.g., clinically documented ruptured right atrium; probable flail chest observed during the autopsy on a decomposed body) localized to the head, neck or chest in three possibly out-of-position drivers pointed to the deployed air bag as a source of injury. In one of 17 side collisions an out-of-position driver sustained a radiographically confirmed C1-C2 dislocation in a minimally intruded vehicle.     

Upper cervical trauma in motor vehicle collisions

Motor vehicle collisions can cause a variety of injuries in pedestrians and vehicle occupants. Fatal and nonfatal trauma to the upper cervical spine, that is, atlanto-occipital junction, atlas and axis, can be part of this spectrum. Certain distinctive injuries (for example, "hangman's fracture") which occur result from the unique anatomic structure of this area and the various disruptive forces such as extension, distraction (tension), compression (axial loading), shear, and inertia generated during collision. Correlation of autopsy findings or radiological information of these cervical injuries or both with scene investigation can be informative not only in the determination of morbidity and mortality, but also in the assessment of injury mechanisms and improvements in occupant protection.     

The effect of the unrestrained back seat passenger on the injuries suffered by drivers and front seat passengers in head-on collisions

In head-on collisions, loose items in the rear of the car, such as luggage or unrestrained back seat passengers can cause substantial loading on the back of the front seats. The purpose of this paper is to study if such loading increases the injury severity for the front seat occupants. Data were collected from all fatal automobile accidents for a period of 1 year in Sweden. Information was collected about the survivors as well as the decreased. Head-on collisions were selected, and the injuries of the front seat occupants were scored according to the Abbreviated Injury Scale (AIS) and the Injury Severity Score (ISS). In evaluating the injury severity, the collision energy was taken into account. The results indicate that belted front seat passengers sustain a higher injury risk with an unrestrained passenger in the back seat. These results are valid for collision speeds below 45 km/h.     

Fatal positional asphyxia associated with rollover crashes

Motor vehicle rollover crashes result in complex occupant kinematics with the potential for severe injury. Five cases of fatal asphyxia in occupants suspended from their safety belt upside down after a rollover crash are presented. These fatalities accounted for 13.5% of all motor vehicle related asphyxia deaths in San Diego County over a 10-year period. This study supports previous research noting that incapacitation due to other injuries, alcohol, or obesity may be associated with fatal positional asphyxia due to inversion during rollovers. Safety belts are proven to prevent serious injury in motor vehicle crashes and should always be worn. However, redesign of the buckle could be considered to permit easier release by an occupant. We also suggest that pre-existing heart disease may contribute to the possibility of a fatal asphyxia outcome. Although this is a rare cause of motor vehicle related death, our results suggest that these are potentially preventable deaths.     

Traumatic testicular displacement in motorcycle drivers

Testicular displacement is a rare clinical presentation of blunt scrotal injury that may take place in road traffic accidents involving motorcycle occupants. We are presenting two cases of motorcycle occupant fatalities, 21 and 24 years of age, where testicular displacement and other signs of groin trauma have been determined. In both cases, discrete external signs of scrotal trauma were noted on examination, while unilateral and bilateral traumatic testicular displacement, respectively, have been documented at autopsy. For motorcycle occupants involved in collision, it is necessary to perform a thorough analysis of injuries, in particular to look for specific trauma arising from fuel-tank impact to genitalia and/or groin. These injuries are of great medico-legal importance both at postmortem and in clinical cases involving motorcycle occupants involved in collision.     

Animal-related fatalities--part I: characteristic autopsy findings and variable causes of death associated with blunt and sharp trauma

Animals may be responsible for an array of potentially lethal injuries. Blunt force injuries characteristically involve larger animals such as cattle or horses that may kick, crush, or trample a victim causing head and facial injuries. Farm workers in particular are at high risk of lethal injuries involving the head and torso. Significant blunt trauma may be found in vehicle occupants after collisions with large animals such as camels or moose. Rarely, zookeepers may be crushed by particularly massive animals such as elephants. Sharp force injuries usually involve carnivore bites, most often from dogs with a "hole and tear" pattern of wounding. Injuries from animals such as alligators and sharks may have a significant component of crushing. Incised wounds may result in death from exsanguination and air embolism. On occasion, blunt or sharp trauma from animal activity may be confused with postmortem damage or with inflicted injury from an assault.     

Forensic Performance Analysis of Load‐Limiting Devices in Automotive Seat Belt Retractors

The introduction of frontal airbags and seatbelt pretensioners for front seat occupants provided an opportunity to address injuries caused by seatbelt loading by introducing load‐limiters, which were intended to reduce belt loading while maintaining proper restraint. Investigation and forensic analysis of real‐world crashes identified that the implementation of these devices, in some circumstances, increased the potential of injury. This paper focuses on the trade‐offs of load‐limiters, that is, the reduction loading to the occupant versus the corresponding increase in seatbelt webbing and occupant movement. If the additional webbing introduced is not controlled, the risk of injury to the occupant is increased and could result in more frequent and severe injuries rather than a reduction. This paper quantifies the webbing introduced by load‐limiter activation through forensic analysis of the seatbelt involved in real‐world crashes and testing and assesses its effect on the injuries sustained by the occupant.     

Serious head and neck injury as a predictor of occupant position in fatal rollover crashes

Serious head and neck injuries are a common finding in fatalities associated with rollover crashes. In some fatal rollover crashes, particularly when ejection occurs, the determination of which occupant was driving at the time of the crash may be uncertain. In the present investigation, we describe the analysis of rollover crash data from the National Automotive Sampling System-Crashworthiness Data System for the years 1997 through 2007 in which we examined the relationship between a serious head and neck injury in an occupant and a specified degree of roof deformation at the occupant's seating position. We found 960 occupants who qualified for the analysis, with 142 deaths among the subjects. Using a ranked composite head and neck injury score (the HNISS) we found a strong relationship between HNISS and the degree of roof crush. As a result of the analysis, we arrived at a predictive model, in which each additional unit increase in HNISS equated to an increased odds of roof crush as follows: for ≥8cm of roof crush compared with <8cm by 4%, for ≥15cm of roof crush compared to <8cm by 6% and for ≥30cm of roof crush compared to <8cm by 11%. We describe two hypothetical scenarios in which the model could be applied to the real world investigation of occupant position in a rollover crash-related fatality.     

Injury Pattern as an Indication of Seat Belt Failure in Ejected Vehicle Occupants

Prior authors have suggested that when occupant ejection occurs in association with a seat belt failure, entanglement of the outboard upper extremity (OUE) with the retracting shoulder belt will invariably occur, leaving injury pattern evidence of belt use. In the present investigation, the authors assessed this theory using data accessed from the NASS‐CDS for ejected front seat occupants of passenger vehicles. Logistic regression models were used to assess the associations between seat belt failure status and injuries. Injury types associated with seat belt failure were significant OUE and head injuries (OR = 3.87, [95% CI 1.2, 13.0] and 3.1, [95% CI 1.0, 9.7], respectively). The two injury types were found to be a predictor of seat belt use and subsequent failure only if combined with a high (≥0.8) precrash probability of belt use. The injury pattern associated with a seat belt failure‐related ejection has limited use in the forensic investigation of crash‐related ejections.     

Motor Vehicle Occupants,Neck Injuries,and Seat Belt Utilization: A 5‐Year Study of Fatalities in New York City

Abstract: Despite the implementation of numerous safety devices in automobiles, vehicular occupant fatalities following collisions remain common. We reviewed all fatalities of vehicular occupants in New York City over a 5‐year period on whom autopsies were performed (437) to determine the incidence of neck injuries and correlate them with seat belt utilization; 26.5% had neck injuries (mild to severe) and only 10.3% of these occupants were confirmed to be wearing seatbelts. Of those that had documentation of seat belt utilization there were twice as many neck injuries in the unbelted group. We highlight two cases of submarining with severe neck injuries that were related to automatic 2‐point shoulder harness restraints without engagement of the lap belt.     

Injury Patterns Sustained in Fatal Motor Vehicle Collisions with Driver's Third‐Generation Airbag Deployment

The Office of the Chief Coroner for Ontario database for 2011–2012 was used to compare fatal injury patterns in drivers whose third‐generation airbags deployed compared to first‐ and second‐generation airbag deployments and airbag nondeployments with and without seatbelt use. There were 110 frontal and offset frontal crashes analyzed. The small sample size meant that the odds of craniocerebral, cervical spinal, thoracic, and abdominal injuries were not statistically different for airbag generation, deployment status, and seatbelt use; however, the risk of fatal thoracic injuries in third‐ and second‐generation cases was increased. Seatbelt usage in third‐ and second‐generation deployment cases reduced the risk of all injuries except abdominal trauma. High severity impacts and occupant compartment intrusion were frequently observed. The analyses in this retrospective study were challenged by data that were not collated in a standardized way and were limited in details about scene, vehicle, and driver variables.     

Cervical airway injuries as a result of impact with steering wheel rim

Motor vehicle occupants may suffer severe cervical airway injuries as the result of impaction with the steering wheel, dashboard, windshield, backseat, and seat belt. Although the steering column is well recognized as a general site of injury infliction, less attention has been directed to components which may be the actual focal point of contact, such as the steering wheel rim. Two cases of cervical airway injury as a result of impact with the steering wheel rim are presented, including one instance of complete laryngotracheal transection. Correlation of injury with crash and postcrash sequences as well as the damaged vehicle will often provide excellent crash injury reconstruction.     

The sensitivity and specificity of control surface injuries in aircraft accident fatalities

Among the important determinations that aircraft crash investigators try to make is which occupant of an aircraft was attempting to control the aircraft at the time of the crash. The presence or absence of certain injuries of the extremities is used to help make this determination. These "control surface injuries" reportedly occur when crash forces are applied to a pilot's hands and feet through the aircraft's controls. We sought to clarify the significance of these injuries and the frequency with which their presence indicates that the decedent was the person that might have been trying to control the aircraft, questions that are frequently asked of the examining pathologist. We studied sequential fatalities of airplane and helicopter crashes in which autopsies were performed by the Office of the Armed Forces Medical Examiner, excluding those that were known to have been incapacitated before the crash and those that were known to have attempted to escape from the aircraft, collecting 100 "qualified" crash decedents. The incidence of control surface injuries was determined for both pilots and passengers. The sensitivity and specificity of control surface injuries were calculated by classifying the decedents into a 4-cell diagnostic matrix. The positive and negative predictive values for control surface injuries were also calculated. Injuries that met the published definitions of control surface injuries had high incidences in passengers, as well as pilots, giving the term control surface injury a diagnostically unacceptable sensitivity and specificity for indicating "a pilot attempting to control an aircraft." We offer caveats and refinements to the definition of these injuries that help to increase the sensitivity and specificity of this term.     

Injury pattern in fatal automobile accident passengers due to rear-end collisions

The article reports on the injury pattern seen in fatally wounded car passengers after rear-end collisions on motorways. The study material included 5 rear-end collisions, in which 9 car occupants (5 drivers and 4 front-seat passengers) were killed. The change in velocity (delta v) was above 60 km/h in all the reported cases. The injury pattern showed the following characteristics: extensive soft-tissue traumatization (subcutaneous haematomas, blood-filled pockets, "décollements") not discernible from outside on the back of the trunk, mostly in the lumbosacral region; dorsal serial rib fractures, often combined with fractures of the spine (including the sacrum and the coccyx) and/or the pelvis; ruptures of the aorta at the typical sites of predisposition; ruptures of the liver and spleen (particularly at the visceral surfaces).     

Esophageal injury in fatal rear-impact collisions

Neck injuries resulting from motor vehicle collisions (MVC), often referred to as whiplash trauma and injury, often demonstrate little or no evidence of significant tissue damage. In rare instances, however, serious injury to the anterior neck organ injuries can result from such trauma. The present study describes esophageal injury associated with rear-impact collisions, based on a unique case report, review of the scientific literature and a query in the National Automotive Sampling System (NASS) database of the US National Highway Traffic Safety Administration. The Medline search and present case study totaled five cases of rear-impact collision-related serious esophageal injury (laceration or rupture). In the four published cases all patients survived, whereas in the presented case study, the patient died due to mediastinitis and sepsis. The NASS query revealed an additional three cases out of a total of 55,926 investigated crashes. All three cases were associated with fatalities. Although no anatomical or bioengineering studies have presented data on the behavior of the esophagus during rear-impact whiplash loading, sudden tensile and/or compressive forces is the likely explanation of injury, often in combination with a local fracture of a vertebral body. In these 8 cases significant esophageal injury carried a substantial (50%) risk of mortality. Clinicians should be aware of the potential for significant complications in the whiplash trauma-exposed patient who complains of chest pain, mid-thoracic pain, discomfort in the neck and throat, respiratory distress, or hoarseness. For those forensic specialists involved in whiplash cases these study results highlight the need to consider esophageal injuries as a rare but potential consequence of whiplash trauma.     

Pulmonary embolization by chorionic villi causing maternal death after a car crash

Throughout the last century, there has been a marked decline in obstetric maternal deaths, resulting in an increase in the proportion of nonobstetric deaths among pregnant women. Trauma, in particular, has become a leading cause of maternal death. We report the case of a 20-year-old primigravid woman who was involved in a motor vehicle crash at 36 weeks gestation. The woman developed abruptio placentae, followed by disseminated intravascular coagulation, adult respiratory distress syndrome, and shock, and died the day after the crash. Widespread pulmonary embolization by chorionic villi was identified at autopsy. This report discusses traumatic maternal deaths, with emphasis on the differences in injury pattern observed in pregnant trauma victims in comparison with other adults. It is important that the pathologist be aware of these problems so that an accurate cause of death can be identified in cases of maternal death after trauma. Also discussed is the relationship between trauma and placental abruption and the mechanism of death in the patient. To the authors' knowledge, this is the first reported case of extensive embolism of chorionic villi to the lungs after trauma.     

Influence of post mortem changes on experimental safety belt injuries

Belt protected car occupants involved on head-on collisions do not seem to suffer as severe injuries as unembalmed cadavers subjected to comparable simulated head-on collisions. Therefore it has been questioned if cadavers constitute adequate test specimens for study of thoracic tolerances. This investigation compares injuries in safety belt wearing living and dead pigs which have been subjected to simulated head-on collisions on an acceleration tract. Tests were performed on all 20 pigs (10 living and 10 dead). The arterial side of the circulatory system of the dead pigs was infused. The force in the safety belts, the intraaortic pressure, the impact velocity and the deceleration of the sled were recorded. The tests were high speed filmed. Post mortem examination of the pigs revealed differences in injury severity. Dead pigs more easily suffered rib fractures. Deformation of the rib cage due to stripping of the periosteum and laceration of surrounding tissue occurred mainly in the dead pigs. Laceration of intrathoracic blood vessels was seen in dead pigs while isolated heart lesions were seen only in living animals. The main cause of these differences in tolerance level seems to be post mortem changes of the mechanical properties of the different tissues. The results are valid for pigs but indicate that great care has to be exercised when results obtained from cadaver experiments are evaluated concerning thoracic tolerance.     

Murder and robbery by vehicular impact: true vehicular homicide

True vehicular homicides are defined as those occurrences in which a motor vehicle is intentionally used as a weapon in taking of a life. A case is presented in which the deceased was traveling in the front passenger seat of a motor car that was deliberately rammed by a heavy jeep that came in the opposite direction, resulting in a serious frontal collision. Immediately after the impact, while the occupants of the car were lying in a dazed condition, the two persons riding in the jeep escaped with a bag containing money that was in the car, leaving the jeep behind. The impact mainly involved the driver's sides of both vehicles. The driver of the car sustained serious injuries but was found to be alive, whereas the front-seat passenger, who did not show any serious external injuries, was found to be in a collapsed state and was pronounced dead on admission to the hospital within 30 minutes of the accident. The autopsy revealed that death was caused by closed hemopericardium from a ruptured right atrium. The evaluation of the external and internal injuries confirmed that the fatal injury and a few serious internal injuries were caused by the seat belt (tertiary-impact injuries). The ruptured right atrium was attributed to blunt abdominal trauma by impacting against the lap belt. The case was a true vehicular homicide in which a motor vehicle had been used as a weapon to kill a person. Various aspects pertaining to road accidents, the safety of the occupants, and the advantage and disadvantage of the safety devices are discussed.     

Death Due to Coronary Artery Insufficiency Following Blunt Trauma to the Chest

There have been numerous reports of sudden cardiac death following blunt trauma to the chest, but there is lack of such references in forensic literature. It is the court of law which makes decision about trauma precipitating natural events. The forensic pathologist is scientifically trained in the medical field and would be in a better position to give clear picture about the victim's general status at the time of death, exact nature and severity of the illness he is suffering from if any. He can also assess the nature and severity of injuries sustained, and thus, his opinion as to the possible role played by the traumatic event in bringing about the death is valuable. This paper will discuss the mechanism of cardiac injury or possible cardiac injury and sudden death of an apparently healthy 36‐year‐old male following blunt chest trauma sustained during alleged assault by his neighbor.