Mark R. Sochor

Fetal outcome in motor-vehicle crashes: effects of crash characteristics and maternal restraint

OBJECTIVE This project was undertaken to improve understanding of factors associated with adverse fetal outcomes of pregnant occupants involved in motor-vehicle crashes. STUDY DESIGN In-depth investigations of crashes involving 57 pregnant occupants were performed. Maternal and fetal injuries, restraint information, measures of external and internal vehicle damage, and details about the crash circumstances were collected. Crash severity was calculated using vehicle crush measurements. Chi-square analysis and logistic regression models were used to determine factors with a significant association with fetal outcome. RESULTS Fetal outcome is most strongly associated with crash severity (P < .001) and maternal injury (P = .002). Proper maternal belt-restraint use (with or without airbag deployment) is associated with acceptable fetal outcome (odds ratio = 4.5, P = .033). Approximately half of fetal losses in motor-vehicle crashes could be prevented if all pregnant women properly wore seat belts. CONCLUSION Higher crash severity, more severe maternal injury, and lack of proper seat belt use are associated with a higher risk of adverse fetal outcome. These results strongly support recommendations that pregnant women use properly positioned seatbelts.

Death of a Child in the Emergency Department

The death of a child in the emergency department (ED) is one of the most challenging problems facing ED clinicians. This revised technical report and accompanying policy statement reaffirm principles of patient- and family-centered care. Recent literature is examined regarding family presence, termination of resuscitation, bereavement responsibilities of ED clinicians, support of child fatality review efforts, and other issues inherent in caring for the patient, family, and staff when a child dies in the ED. Appendices are provided that offer an approach to bereavement activities in the ED, carrying out forensic responsibilities while providing compassionate care, communicating the news of the death of a child in the acute setting, providing a closing ritual at the time of terminating resuscitation efforts, and managing the child with a terminal condition who presents near death in the ED.

Postmortem Computed Tomography as an Adjunct to Autopsy for Analyzing Fatal Motor Vehicle Crash Injuries: Results of a Pilot Study

BACKGROUND Detailed fatal injury data after fatal motor vehicle crashes (MVC) are necessary to improve occupant safety and promote injury prevention. Autopsy remains the principle source of detailed fatal injury data. However, procedure rates are declining because of a range of technical, ethical, and religious concerns. Postmortem computed tomography (PMCT) is a potential alternative or adjunct to autopsy which is increasingly used by forensic researchers. However, there are only limited data regarding the utility of PMCT for analysis of fatal MVC injuries. METHODS We performed whole body PMCT and autopsy on six subjects fatally injured in MVC in a single county in Michigan. All injuries detected by either method were coded using the Abbreviated Injury Scale (AIS). Severe injuries, defined as AIS 3 or higher (AIS 3+), were tallied for each forensic procedure to allow a comparison of relative diagnostic performance. RESULTS A total of 46 AIS 3+ injuries were identified by autopsy and PMCT for these cases. The addition of PMCT to autopsy increased overall detection of AIS 3+ injuries (all types) by 28%. PMCT detected 27% more AIS 3+ skeletal injuries than autopsy but 25% less soft tissue injuries. CONCLUSIONS Use of PMCT improves the detection of AIS 3+ injuries after fatal MVC compared with isolated use of autopsy and also produces a highly detailed permanent objective record. PMCT appears to improve detection of skeletal injury compared with autopsy but is less sensitive than autopsy for the detection of AIS 3+ soft tissue injuries. Neither autopsy nor PMCT identified all AIS 3+ injuries revealed by the combination of the two methodologies. This suggests that PMCT should be used as an adjunct to autopsy rather than a replacement whenever feasible.

Effect of seat belt pretensioners on human abdomen and thorax: Biomechanical response and risk of injuries.

BACKGROUND: A better coupling of the occupant to the car seat in the early phase of a frontal or far side impacts using pretensioner systems may reduce the likelihood of the submarining effect or increases the likelihood of seat belt engaging the shoulder, respectively. However, the high belt forces may also increase the risk of upper body injuries to the vehicle occupant (especially in abdominal region). It was hypothesized that human body characteristics, such as body mass index (BMI) influence the biomechanical response and injury outcome to the abdominal regions during static pretensioning deployment tests. METHODS: Four postmortem human specimens (PMHS), in a BMI range from 15.6 to 31.2, were positioned in production seats in a normal passenger position and were restrained using a standard three-point belt system. The pretension forces in the belts were generated at two points (retractor and right anchorage) or at all three locations (retractor, left anchorage, and right anchorage). An optical motion capture system and acceleration cubes mounted to the lumbar spine were used to measure the abdomen deformation during testing. RESULTS: The normalized deflections of the thorax recorded at the level of fourth rib were under 10% (noninjury level). Two different patterns were observed in the time histories of abdominal penetration rate in the four PMHSs associated with lower and higher BMI. Abdominal injuries (spleen lacerations) were observed only in the two PMHS with highest BMI. CONCLUSION: Based on data from this study and similar data from the literature, belt velocity and FmaxCmax were shown to be the best injury predictors for injury risk analysis for Abbreviated Injury Scale 2+ and for Abbreviated Injury Scale 3+ injuries, respectively.

BioTab--a new method for analyzing and documenting injury causation in motor-vehicle crashes.

Objective: To describe a new method for analyzing and documenting the causes of injuries in motor vehicle crashes that has been implemented since 2005 in cases investigated by the Crash Injury Research Engineering Network (CIREN). Methods: The new method, called BioTab, documents injury causation using evidence from in-depth crash investigations. BioTab focuses on developing injury causation scenarios (ICSs) that document all factors considered essential for an injury to have occurred as well as factors that contributed to the likelihood and/or severity of an injury. The elements of an injury causation scenario are (1) the source of the energy that caused the injury, (2) involved physical components (IPCs) contacted by the occupant that are considered necessary for the injury to have occurred, (3) the body region or regions contacted by each IPC, (4) the internal paths between body regions contacted by IPCs and the injured body region, (5) critical intrusions of vehicle components, and (6) factors that contributed to the likelihood and/or the severity of injury. Results: Advantages of the BioTab method are that it • attempts to identify all factors that cause or contribute to clinically significant injuries, • allows for coding of scenarios where one injury causes another injury, • associates injuries with a source of energy and allows injuries to be associated with sources of energy other than the crash, such as air bag deployment energy, • allows for documenting scenarios where an injury was caused by two different body regions contacting two different IPCs, • identifies and documents the evidence that supports ICSs and IPCs, • assigns confidence levels to ICSs and IPCs based on available evidence, and • documents body region and organ/component-level “injury mechanisms” and distinguishes these mechanisms from ICSs. Conclusion: The BioTab method provides for methodical and thorough evidenced-based analysis and documentation of injury causation in motor vehicle crashes.

Side Impact PMHS Thoracic Response With Large-Volume Air Bag

Objective: The objective of this study is to assess the response of postmortem human subjects (PMHS) to a large-volume side air bag in a fully instrumented and well-controlled side impact test condition. Methods: Three adult male PMHS were subjected to right-side pure lateral impacts. Each stationary seated subject was struck at 4.3 ± 0.1 m/s by a rigid wall installed on a 1700-kg rail-mounted sled. Each subject was held stationary by a system of tethers until immediately prior to being impacted by the moving wall. A large side air bag was mounted to the wall and deployed so that it was fully inflated at the time it contacted the subjects right side. The load wall consisted of an adjustable matrix of 15 individual plates, each supported by a 5-axis load cell that recorded the interaction between the subject and impacting wall. Two-dimensional (external) torso deformation was provided by a chest band that encircled the torso at the level of the sixth rib laterally. Triaxial acceleration was measured at the head, spine, and sacrum via 3 orthogonal accelerometers mounted to the same bone-mounted hardware that held the marker clusters used for kinematic analysis. Results: Peak pelvic load normal to the wall averaged 6.8 kN, which was over 5 times that recorded for the shoulder (1.3 kN) and the thorax (1.2 kN). Lateral chest deflection ranged from 9 to 21 mm. Two of the 3 subjects sustained 2 and 9 fractures, respectively. Conclusions: Two of the 3 PMHS sustained rib fractures despite low levels of thorax deflection. We attribute this finding to individual variability in subject injury tolerance. Other response parameters exhibited lower levels of variability and characterize PMHS response to a potentially beneficial side impact countermeasure. Supplemental materials are available for this article. Go to the publishers online edition of Traffic Injury Prevention to view the supplemental file.

Ambulance transport rates after motor vehicle collision for older vs. younger adults: A population-based study

Older adults are at greater risk than younger adults for life-threatening injury after motor vehicle collision (MVC). Among those with life-threatening injury, older adults are also at greater risk of not being transported by emergency medical services (EMS) to an emergency department. Despite the greater risk of serious injury and non-transportation among older adults, little is known about the relationship between patient age and EMS transportation rates for individuals experiencing MVC. We describe transport rates across the age-span for adults seen by EMS after experiencing MVC using data reported to the North Carolina Department of Motor Vehicles between 2008 and 2011. Of all adults aged 18 years and older experiencing MVC and seen by EMS (n=484,310), 36.3% (n=175,768) were transported to an emergency department. Rates of transport for individuals seen by EMS after MVC increased only a small amount with increasing patient age. After adjusting for potential confounders of the relationship between patient age and the decision to transport (patient gender, patient race, air bag deployment, patient trapped or ejected, and injury severity), transport rates were: age 18-64=36.0% (95% confidence interval [CI], 35.9-36.2%); age 65-74=36.6% (95% CI, 36.0-37.1%); age 75-84=37.3% (95% CI, 36.5-38.1%), and age 85-94=38.2% (95% CI, 36.7-39.8%). In North Carolina between 2008 and 2011, the transportation rate was only slightly higher for older adults than for younger adults, and most older adults experiencing MVC and seen by EMS were not transported to the emergency department. These findings have implications for efforts to improve the sensitivity of criteria used by EMS to determine the need for transport for older adults experiencing MVC.

Descriptions of Motor Vehicle Collisions by Participants in Emergency Department-Based Studies: Are They Accurate?

Introduction We examined the accuracy of research participant characterizations of motor vehicle collisions (MVC). Methods We conducted an emergency department-based prospective study of adults presenting for care after experiencing an MVC. Study participants completed a structured clinical interview that assessed the number of lanes of the road where the collision took place, vehicle type, road condition, speed limit, seat belt use, airbag deployment, vehicle damage, time of collision, and use of ambulance transportation. Study participant data were then compared with information recorded by Michigan State Police at the scene of the MVC. Agreement between research participant reports and police-reported data were assessed by using percentage agreement and κ coefficients for categorical variables and correlation coefficients for continuous variables. Results There were 97 study participants for whom emergency department interviews and Michigan State Police Report information were available. Percentage agreement was 51% for number of lanes, 76% for car drivability, 88% for road condition, 91% for vehicle type, 92% for seat belt use, 94% for airbag deployment, 96% for speed limit, 97% for transportation by ambulance, and 99% for vehicle seat position. κ values were 0.32 for seat belt use, 0.34 for number of lanes, 0.73 for vehicle type, 0.76 for speed limit, 0.77 for road condition, 0.87 for airbag deployment, 0.90 for vehicle seat position, and 0.94 for transport by ambulance. Correlation coefficients were 0.95 for the time of the collision, and 0.58 for extent of damage to the vehicle. Most discrepancies between patients and police about extent of vehicle damage occurred for cases in which the patient reported moderate or severe damage but the police reported only slight damage. Conclusion For most MVC characteristics, information reported by research participants was consistent with police-reported data. Agreement was moderate or high for characteristics of greatest relevance to injury biomechanics. These results suggest that research participant report is an acceptable source of collision information.

Large-event medicine--event characteristics impacting medical need.

Large events have been defined in many ways, from the vague description of a focused gathering of people to the more specific description of an event with at least 1,000 spectators and participants who are gathered at a specific location for a defined period of time. Regardless of the definition applied, the actual medical requirements vary considerably from one event to the next. The ability to predict these medical needs allows for the provision of adequate medical support. Many factors contribute to medical need at a large event, including event type, weather (particularly heat index), the presence of alcohol and / or illicit drugs, the number of participants, event duration, crowd demographics, and venue characteristics. This review will focus on the various features of large events such that the medical planner can better understand the challenge and provide adequate resource for patient care.

Biomechanical response targets for physical and computational models of the pediatric trunk.

Objectives: This paper quantifies pediatric thoracoabdominal response to belt loading to guide the scaling of existing adult response data and to assess the validity of a juvenile porcine abdominal model for application to the development of physical and computational models of the human child. Methods: Table-top belt-loading experiments were performed on 6, 7, and 15 year-old pediatric post-mortem human subjects (PMHS). Response targets are reported for diagonal belt and distributed loading of the anterior thorax and for horizontal belt loading of the abdomen. Results: The pediatric PMHS exhibited abdominal response similar to the swine, including the degree of rate sensitivity. The thoraces of the PMHS were as stiff as, or slightly more stiff than, published adult corridors. Conclusions: An assessment of age-related changes in thoracic stiffness suggests that the effective stiffness of the chest increases through the fourth decade of life and then decreases, resulting in stiffness values similar for children and elderly adults.