Motor Vehicle Driving-Related Anxiety in Patients Undergoing Cardioverter Defibrillator Implantation and Cardiac Resynchronization Therapy With Defibrillators

BACKGROUND

Reducing anxiety about motor vehicle driving in patients receiving implantable cardioverter defibrillators and cardiac resynchronization therapy with defibrillators is important not only for improving quality of life but also for preventing vehicle collisions owing to driver distraction. This study aimed to clarify the driving-related anxiety of patients with these defibrillators and the factors that predict such anxiety.

METHODS

We conducted a cross-sectional survey using a self-administered questionnaire of patients who had been driving a vehicle after device implantation at a general hospital between August 2018 and November 2019.

RESULTS

The mean age was 60.8 ± 12.6 years. The reasons for implantation were primary prevention in 47 patients and secondary prevention in 30 patients. A total of 16 patients experienced anxiety about driving and 61 did not. Significantly more younger patients (mean age of 50.4 vs. 63.6 years, p < 0.001) and those with implantable cardioverter defibrillators had anxiety (100% vs. 73.8%, p = 0.02). Multivariable analysis indicated that age was the only independent factor that predicted driving-related anxiety (odds ratio, 0.937; 95% confidence interval, 0.883-0.993).

CONCLUSIONS

Identifying and addressing driving-related anxiety in patients (particularly young patients) with defibrillators is important in preventing motor vehicle collisions and improving quality of life.

Comfortable Seatbelts for Pregnant Women with Twins in Japan: A Cross-Sectional Observational Study on Seatbelt Usage

Optimal seatbelt practices for pregnant women with twins at different gestational ages remain uncertain. To offer recommendations for a comfortable seatbelt system, this cross-sectional observational study explored seatbelt usage and driving habits among women with twins across various pregnancy stages through an online survey that explored driving conditions and comfortable seatbelts at different stages of pregnancy. Women who drove daily before their pregnancy with twins decreased their driving frequency as the pregnancy progressed. Correct seatbelt usage was lower and no seatbelt usage was higher among pregnant women with twins than those with singleton pregnancies. They adapted their seatbelt-wearing techniques to minimise pressure on the chest in the first and third trimesters and the abdomen from the second trimester onwards. The comfortable seatbelts were those that could alleviate belt pressure, featuring waist belts to reduce pressure, wider belts to avoid localised pressure, and shoulder belts resembling a backpack type. When wearing a seatbelt, avoiding pressure on the thorax and abdomen is key for pregnant women with twins. This study suggests that the suitability of driving for pregnant women with twins in their last trimester and the reliability of seatbelts designed for such women should be further examined and validated.

Prediction of Placental Abruption of Pregnant Women Drivers with Various Collision Velocities, Seatbelt Positions and Placental Positions-Analysis with Novel Pregnant Occupant Model

The aims of this study were as follows: the (a) creation of a pregnant occupant finite element model based on pregnant uterine data from sonography, (b) development of the evaluation method for placental abruption using this model and (c) analysis of the effects of three factors (collision speed, seatbelt position and placental position) on the severity of placental abruption in simulations of vehicle collisions. The 30-week pregnant occupant model was developed with the uterine model including the placenta, uterine-placental interface, fetus, amniotic fluid and surrounding ligaments. A method for evaluating the severity of placental abruption on this pregnant model was established, and the effects of these factors on the severity of the injury were analyzed. As a result, a higher risk of placental abruption was observed in high collision speeds, seatbelt position over the abdomen and anterior-fundal placenta. Lower collision speeds and seatbelt position on the iliac wings prevented severe placental abruption regardless of placental positions. These results suggested that safe driving and keeping seatbelt position on the iliac wings were essential to decrease the severity of this injury. From the analysis of the mechanism for placental abruption, the following hypothesis was proposed: a shear at adhesive sites between the uterus and placenta due to direct seatbelt loading to the uterus.

Does abdominal protrusion in pregnant women affect abdominal injury severity in motor vehicle collisions? A nationwide database study

AIMS

Some pregnant women avoid vehicle driving owing to the risk of contact between their protruding abdomen and steering wheel. This study was performed to determine whether abdominal protrusion in late-term pregnant car users affects the occurrence and severity of abdominal injuries in motor vehicle collisions using a national crash database.

METHODS

The National Automotive Sampling System/Crashworthiness Data System was used to analyse maternal background, collision characteristics, outcome and Abbreviated Injury Scale (AIS) scores for the body regions of all persons involved in the collision.

RESULTS

Comparison of pregnant and non-pregnant women in the driver's seat showed no significant differences in the rate of AIS scores of ≥2 (2+) for abdominal injuries and female outcomes. Comparison of use of the driver's seat and front passenger's seat by pregnant women showed no significant difference in rate of AIS 2+ injuries or in maternal and fetal outcomes. Comparison of pregnant women with a gestational age of ≤27 and >27 weeks in the driver's seat showed no significant differences in rate of AIS 2+ injuries or in maternal and fetal outcomes.

CONCLUSIONS

Based on the data from relatively low-speed frontal collisions, obstetrician/gynaecologists should advise pregnant women that they do not need to change their preferred car seat from the driver's seat to another seat because of fear of contact between their protruding abdomen and the vehicle interior.

The characteristics and prevalence of patent foramen ovale in Japanese people: a study using material from forensic autopsies

Racial and ethnic differences in the prevalence of patent foramen ovale have been suggested, but there are insufficient data to confirm the situation. Studies have also not investigated detailed morphological changes in the fossa ovalis by age. This study therefore aimed to clarify the characteristics of the fossa ovalis and determine the frequency of patent foramen ovale in Japanese people, using materials from forensic autopsies. A total of 359 hearts were obtained during forensic autopsies (from 223 males and 136 females, aged from 0 to 94 years). Overall, prevalence of patent foramen ovale was 12.5%, but it was significantly higher among those under 20 years old (66.7% in males, 38.5% in females). The area of the fossa ovalis linearly increased with age in both sexes. The prevalence of patent foramen ovale was lower in Japanese adults than previously found in either White or Black people. The ratio of the area of the fossa ovalis to the heart weight was nearly constant.

Association between eGFR and neurological outcomes among patients with out-of-hospital cardiac arrest: A nationwide prospective study in Japan

Aim

We aimed to investigate the association between estimated glomerular filtration rate and prognosis in out-of-hospital cardiac arrest patients and explore the heterogeneity of the association.

Methods

Patients experiencing out-of-hospital cardiac arrest due to medical causes and registered in the JAAM-OHCA Registry between June 2014 and December 2019 were stratified into shockable rhythm, pulseless electrical activity, and asystole groups according to the cardiac rhythm at the scene. The primary outcome was a 1-month favorable neurological status. Adjusted odds ratios with 95% confidence intervals were calculated to investigate the association between estimated glomerular filtration rate and outcomes using a logistic model.

Results

Of the 19,443 patients included, 2769 had initial shockable rhythm at the scene, 5339 had pulseless electrical activity, and 11,335 had asystole. As the estimated glomerular filtration rate decreased, the adjusted odds ratio for a 1-month favorable neurological status decreased among those with initial shockable rhythm (estimated glomerular filtration rate, adjusted odds ratio [95% CI]: 45-59 mL/min/1.73 m2, 0.61 [0.47-0.79]; 30-44 mL/min/1.73 m2, 0.45 [0.32-0.62]; 15-29 mL/min/1.73 m2, 0.35 [0.20-0.63]; and <15 mL/min/1.73 m2, 0.14 [0.07-0.27]). Estimated glomerular filtration rate was associated with neurological outcomes in patients aged <65 years with initial shockable rhythm but not in those aged >65 years or patients with initial pulseless electrical activity or asystole.

Conclusion

The estimated glomerular filtration rate is associated with neurological prognosis in out-of-hospital cardiac arrest patients with initial shockable rhythm at the scene but not in those with initial non-shockable rhythm.

Proposal for nationwide registration of injuries or fatalities in wheelchair user motor vehicle passengers in Japan

One consequence of population aging is an increase in the number of older wheelchair users. They often board the motor vehicle from the rear for moving. Recently, wheelchair user vehicle passengers have involved in motor vehicle collisions and died. A three-point seatbelt does not adequately fit most wheelchair user passengers because of the way that the wheelchair is constructed. Therefore, owing to the movement of the body immediately after the collision, the wheelchair user passengers attacked their body to the interior of the vehicle or suffered from the intrusion of the lap belt into the abdomen, subsequently suffered from severe head, chest or abdominal injuries. According to the review of all fatal motor vehicle collisions in Shiga Prefecture, Japan, which has a population of approximately 1.4 million, from 2017 to 2022, the rate of wheelchair users in fatal motor vehicle passenger increased from 3.6% in 2017 to 2019 to 7.8% in 2020 to 2022. Therefore, there is a risk that substantial numbers of wheelchair user passengers involved in motor vehicle collisions will die. However, in Japan, there are no official statistics on the involvement of wheelchair user passengers in motor vehicle collisions. Therefore, we propose a nationwide registration of injuries and fatalities in wheelchair user passengers. Investigating the mechanisms of injury in wheelchair user passengers would contribute to the development of safety measures, especially for restraint systems. Established preventive measure would contribute to the decrease of fatally or severely injured motor vehicle collision passengers.

HIV/AIDS knowledge level, awareness of public health centers and related factors: a cross-sectional study among Brazilians in Japan

BACKGROUND

Accurate information is essential so that HIV infection can be detected in time for initiation of HIV/AIDS treatment. Immigrants are at high risk for delayed HIV testing and diagnosis, but foreign residents in Japan also seem to face barriers to accessing HIV/AIDS care. We aimed to assess their knowledge level of HIV/AIDS and awareness of public health centers in Japan (PHCs), and to explore factors related to these items.

METHODS

We conducted a cross-sectional study of Brazilians, the largest group of foreigners living in Shiga, using an anonymous, self-administered questionnaire survey in Brazilian Portuguese and Japanese via the Internet and mail. A multiple logistic regression analysis was used to examine the factors related to "Knowledge of HIV/AIDS" and "Awareness of PHCs".

RESULTS

A total 182 Brazilians responded. More than half of them were beginners in Japanese. Most respondents were familiar with HIV/AIDS, but only 58% knew the existence of PHCs, and only 25% knew that HIV testing is available at PHCs free of charge and anonymously. A multiple logistic regression analysis showed that PHCs were less recognized by those with intermediate (odds ratio: 5.70, 95% confidence interval: 1.53-21.23) and beginner (odds ratio: 6.81, 95% confidence interval: 1.98-23.45) Japanese proficiency than by those with advanced.

CONCLUSIONS

This survey revealed the knowledge level of HIV/AIDS and awareness of PHC among Brazilians in Shiga. Their lack of awareness of PHCs due to language barriers may lead to delays in HIV testing among them. Therefore, it is important for PHCs to disseminate information about medical services related to HIV/AIDS in Portuguese and plain Japanese to facilitate their access to HIV testing. However, PHC efforts alone are not enough. Medical interpreters who are familiar with Brazilian culture and customs, and the clinics that employ them, could help the Brazilian community and PHCs to overcome the language barrier and provide efficient and appropriate medical care to Brazilians. This would be one way to eliminate delays in HIV testing for Brazilians in Shiga.

Factors predicting oral and maxillofacial fractures after falling and factors predicting the duration of treatment

BACKGROUND/AIM

The first objective of this study was to identify predictive factors for oral and maxillofacial fractures at the initial response to the patient. The second objective was to determine the factors influencing the incidence of treatment duration of more than 1 month using the information shown in the medical record.

MATERIALS AND METHODS

Hospital records from 2011 to 2019 were reviewed to identify patients who had sustained oral and maxillofacial injuries by falling or falling from a height. Patterns and types of oral and maxillofacial injury, injury severity, and background of the injury were collected from the hospital records. The variables independently associated with a treatment duration of more than 1 month were determined by logistic regression analysis.

RESULTS

In total, 282 patients (150 men, 132 women; median age, 17.5 years) were selected for analysis. Maxillofacial fractures were observed in 20.9% of patients (59/282); among these, mandibular fractures were the most common (47/59). Logistic regression analysis showed that age (odds ratio [OR], 1.026), nighttime occurrence (OR, 2.192), and upper face injury (OR, 20.704) were independent predictive factors for having a maxillofacial fracture. Additionally, the number of injured teeth (OR, 1.515) and the use of intermaxillary fixation (OR, 16.091) were independent predictors of treatment duration of more than 1 month.

CONCLUSIONS

These results may be useful in the initial management of maxillofacial injuries in terms of better-informing patients injured by falling their expected treatment duration and managing the psychological impacts of a long treatment duration.

Predictive Factors of the Fatality of Motor Vehicle Passengers Involved in Far-Side Lateral Collisions: A National Crash Database Study

Although the risks faced by passengers in near-side lateral collisions are understood, and despite the presence of side airbags for injury prevention, passengers involved in far-side lateral collisions also suffer serious and fatal injuries. The objective of this study was to determine the independent predictive factors of fatality of motor vehicle passengers involved in far-side lateral collisions. Using 2010 records from the National Automotive Sampling System/Crashworthiness Data System (NASS/CDS), we selected 86 fatal and 325 non-fatal passengers with an Abbreviated Injury Scale (AIS) score of 2 or more. The background and injury severity of the passengers and collision characteristics were compared between the two groups. In a multivariable logistic regression analysis, variables independently associated with fatalities were female sex (Ref, male) (odds ratio [OR], 0.396), age (OR, 1.029), body mass index (OR, 1.057), total delta-V (OR, 1.031), head AIS score (OR, 1.679), chest AIS score (OR, 1.330), and abdomen AIS score (OR, 1.294). This is the first report to determine factors affecting fatality in passengers involved in far-side lateral collisions. Improving the safety of the vehicle interior, such as by including additional seatbelt systems or a side airbag that deploys between seats, might help to avoid fatalities, and reduce injury severity.

Affecting Factors of Prostate Volume in Forensic Autopsied Decedents

Because decedents undergoing forensic autopsies would have behaved normally before death, prostate volume according to age group can be confirmed with forensic autopsy materials. The objectives of this study were to first confirm the current prostate volume by age and then determine diseases that can influence prostate volume using forensic autopsy materials. Prostate specimens were collected from forensic autopsies performed at Shiga University of Medical Science, Japan, between January 2015 and December 2019. Overall, 207 decedents were included in the study. Prostate volume was measured by the Archimedes' principle. Concomitant diseases were determined by the past medical histories and autopsy results. The mean crude prostate volume was 29.1 ± 10.3 mL (range, 2.8-88.0 mL). The crude prostate volume increased with age. The mean corrected prostate volume (divided by body surface area) was significantly higher in patients with atherosclerosis than in those without. However, multiple regression analysis revealed that only age influenced the corrected prostate volume. Age was the only significant influencing factor for prostate volume. We propose applying age estimation using prostate volume for forensic medicine purposes. Because prostate volume was not influenced by concomitant disease, it would be valuable to estimate the decedent's age using the prostate volume.

Increased CT Use and No Change in Injury Severity among Child Motor Vehicle Victims: A National Trauma Database Study in Japan

The number of fatalities associated with traffic accidents has been declining owing to improvements in vehicle safety performance and changes in the law. However, injuries in children can lead to social and economic losses. We examined 10-year changes in the characteristics of traffic trauma among pediatric motor vehicle passengers by analyzing data from the Japan Trauma Data Bank (JTDB). Among the 36,715 injured motor vehicle passengers under the age of 15 years who were registered in the JTDB from 2004 to 2019, we compared the groups injured during 2004-2007 (n = 94) and 2017-2019 (n = 203). Physiologically, the 2004-2007 group had a lower body temperature and Glasgow Coma Scale score as well as a higher mortality. Anatomical severity was higher in the 2004-2007 group for the head, face, and neck, according to the Abbreviated Injury Scale. In terms of treatment, only craniotomy as a primary surgery was significantly lower in the 2017-2019 group. The 2017-2019 group had significantly higher rates of receiving whole-body computed tomography (CT). Because the rate of performing CT has increased, with no changes in the injury severities of the trunk and extremities, limiting the number of CT examinations is suggested for pediatric motor vehicle passengers involved in road traffic collisions. The severity of trunk and extremity injuries has not improved in more than 10 years; further preventive measures for these injuries should be considered.

RhoA rescues cardiac senescence by regulating Parkin-mediated mitophagy

Heart failure is one of the leading causes of death worldwide. RhoA, a small GTPase, governs actin dynamics in various tissue and cell types, including cardiomyocytes; however, its involvement in cardiac function has not been fully elucidated. Here, we generated cardiomyocyte-specific RhoA conditional knockout (cKO) mice, which demonstrated a significantly shorter lifespan with left ventricular dilation and severely impaired ejection fraction. We found that the cardiac tissues of the cKO mice exhibited structural disorganization with fibrosis and also exhibited enhanced senescence compared with control mice. In addition, we show that cardiomyocyte mitochondria were structurally abnormal in the aged cKO hearts. Clearance of damaged mitochondria by mitophagy was remarkably inhibited in both cKO cardiomyocytes and RhoA-knockdown HL-1 cultured cardiomyocytes. In RhoA-depleted cardiomyocytes, we reveal that the expression of Parkin, an E3 ubiquitin ligase that plays a crucial role in mitophagy, was reduced, and expression of N-Myc, a negative regulator of Parkin, was increased. We further reveal that the RhoA-Rho kinase axis induced N-Myc phosphorylation, which led to N-Myc degradation and Parkin upregulation. Re-expression of Parkin in RhoA-depleted cardiomyocytes restored mitophagy, reduced mitochondrial damage, attenuated cardiomyocyte senescence, and rescued cardiac function both in vitro and in vivo. Finally, we found that patients with idiopathic dilated cardiomyopathy without causal mutations for dilated cardiomyopathy showed reduced cardiac expression of RhoA and Parkin. These results suggest that RhoA promotes Parkin-mediated mitophagy as an indispensable mechanism contributing to cardioprotection in the aging heart.

Physiological status and anatomical severity factors associated with child versus adult bicyclist fatalities based on a national trauma dataset

Bicyclists still account for the majority of child deaths in traffic accidents, despite a gradual decrease in incidence. Therefore, we investigated factors associated with child and adult bicyclist fatalities. In this retrospective study, we used data from a national hospital-based database, the Japan Trauma Data Bank. Data from 2004 to 2019 were obtained for child cyclists (5-18 years; n = 4832) and adult cyclists (26-45 years; n = 3449). In each age group, physiological variables, outcomes, and injury severity were compared between fatal and non-fatal cases. Multivariate logistic regression was performed to determine factors associated with fatality. In adults, fatality was associated with lower values for body temperature, Glasgow Coma Scale score, and Abbreviated Injury Scale (AIS) score for the neck and upper extremities, and with higher values for respiratory rate, heart rate, focused assessment with sonography for trauma positivity rate, and AIS scores for the head, chest, and abdomen. In children, fatality was associated with lower values for body temperature and the Glasgow Coma Scale score, and with higher values for the AIS chest score. These findings point to factors associated with bicyclist fatalities and may help in the development of effective strategies to reduce these fatalities.

Severity of Placental Abruption in Restrained Pregnant Vehicle Drivers: Correct Seat Belt Use Confirmed by Finite Element Model Analysis

Despite wearing a seat belt, pregnant drivers often suffer from negative fetal outcomes in the event of motor accidents. In order to maintain the safety of pregnant drivers and their fetuses, we assessed the severity of placental abruption caused by motor vehicle collisions using computer simulations. We employed a validated pregnant finite element model to determine the area of placental abruption. We investigated frontal vehicle collisions with a speed of 40 km/h or less involving restrained pregnant drivers with a gestational age of 30 weeks. For a crash speed of 40 km/h, the placental abruption area was 7.0% with a correctly positioned lap belt across the lower abdomen; it was 36.3% with the belt positioned at the umbilicus. The area of placental abruption depended on collision speed, but we found that with a correctly positioned belt it likely would not lead to negative fetal outcomes. We examined the effects on placental abruptions of reconfiguring seat belt width and force limiter setting. A wider lap belt and lower force limiter setting reduced the area of placental abruption to 3.5% and 1.1%, respectively; however, they allowed more forward movement upon collision. A 2.5 kN force limiter setting may be appropriate with respect to both forward movement and reduced placental abruption area. This study confirmed the importance of correctly using seat belts for pregnant drivers. It provides valuable evidence about improving safety equipment settings.

Comparison of the Injury Mechanism between Pregnant and Non-Pregnant Women Vehicle Passengers Using Car Crash Test Dummies

This paper analyzes the kinematics and applied forces of pregnant and non-pregnant women dummies sitting in the rear seat during a frontal vehicle collision to determine differences in the features of abdominal injuries. Sled tests were conducted at 29 and 48 km/h with pregnant and non-pregnant dummies (i.e., MAMA IIB and Hybrid III). The overall kinematics of the dummy, resultant acceleration at the chest, transrational acceleration along each axis at the pelvis, and loads of the lap belt and shoulder belt were examined. The belt loads were higher for the MAMA IIB than for the Hybrid III because the MAMA IIB had a higher body mass than the Hybrid III. The differences in the lap belt loads were 1119 N at 29 km/h and 1981-2365 N at 48 km/h. Therefore, for restrained pregnant women sitting in the rear seat, stronger forces may apply to the lower abdomen during a high-velocity frontal collision. Our results suggest that for restrained pregnant women sitting in the rear seat, the severity of abdominal injuries and the risk of a negative fetal outcome depend on the collision velocity.

Dysmenorrhea due to undiagnosed obstructed hemi-vagina and ipsilateral renal anomaly syndrome can become a cause of suicide

Background

A Japanese woman in her early twenties had committed suicide, jumped from a 25-meter high bridge into a lake. She had been suffering from severe dysmenorrhea and general fatigue monthly.

Results

A forensic autopsy revealed indications of a bicorporeal uterus, obstructed hemi-vagina, and ipsilateral renal agenesis, which lead to a diagnosis of obstructed hemi-vagina and ipsilateral renal anomaly (OHVIRA) syndrome. On the right side of the uterus, an enclosed cavity composed of black clots was observed. Histological findings suggested that her endometrium was in the early proliferative phase, implying that she was in the menstrual phase just before her death. She may have been suffering from severe lower abdominal pain from the increased pressure of the closed uterus cavity.

Conclusions

This case indicates that dysmenorrhea from undiagnosed OHVIRA syndrome can possibly lead to a suicide attempt. In Japan, because suicide was the leading cause of death for people aged 15 to 39 in 2019, preventive measures for suicide should be promoted. The present case also suggests that intervention for dysmenorrhea may prevent this in adolescent woman.

Factors Affecting the Severity of Placental Abruption in Pregnant Vehicle Drivers: Analysis with a Novel Finite Element Model

We clarified factors affecting the severity of placental abruption in motor vehicle collisions by quantitively analyzing the area of placental abruption in a numerical simulation of an unrestrained pregnant vehicle driver at collision velocities of 3 and 6 m/s. For the simulation, we constructed a novel finite element model of a small 30-week pregnant woman, which was validated anthropometrically using computed tomography data and biomechanically using previous examinations of post-mortem human subjects. In the simulation, stress in the elements of the utero–placental interface was computed, and those elements exceeding a failure criterion were considered to be abrupted. It was found that a doubling of the collision velocity increased the area of placental abruption 10-fold, and the abruption area was approximately 20% for a collision velocity of 6 m/s, which is lower than the speed limit for general roads. This result implies that even low-speed vehicle collisions have negative maternal and fetal outcomes owing to placental abruption without a seatbelt restraint. Additionally, contact to the abdomen, 30 mm below the umbilicus, led to a larger placental abruption area than contact at the umbilicus level when the placenta was located at the uterus fundus. The results support that a reduction in the collision speed and seatbelt restraint at a suitable position are important to decrease the placental abruption area and therefore protect a pregnant woman and her fetus in a motor vehicle collision.

Factors Affecting Death and Severe Injury in Child Motor Vehicle Passengers

Saving children from motor vehicle collisions is a high priority because the injury rate among motor vehicle passengers has been increasing in Japan. This study aimed to examine the factors that influence death and serious injury in child motor vehicle passengers to establish effective preventive measures. To identify these factors, we performed a retrospective study using a nationwide medical database. The data of child motor vehicle passengers younger than 15 years (n = 1084) were obtained from the Japanese Trauma Data Bank, registered from 2004 to 2019. Physiological variables, outcomes, and injury severity were compared between fatal and non-fatal patients and between those with and without severe injuries. Multivariate logistic regression analysis was performed to determine factors affecting fatality and severe injury. The Glasgow Coma Scale score (odds ratio (OR): 1.964), body temperature (OR: 2.578), and the Abbreviated Injury Scale score of the head (OR: 0.287) were identified as independent predictors of a non-fatal outcome. Systolic blood pressure (OR: 1.012), the Glasgow Coma Scale score (OR: 0.705), and Focused Assessment with Sonography for Trauma positivity (OR: 3.236) were identified as independent predictors of having severe injury. Decreasing the severity of head injury is the highest priority for child motor vehicle passengers to prevent fatality and severe injury.