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Objective: Cross-chest clips are widely used in North American child restraints but are less common in other countries, partially due to concerns over anterior neck contacts in frontal crashes. The...

Traffic crashes have high mortality and morbidity for young children. Though many specialized child restraint systems improve injury outcomes, no large-scale studies have investigated the cross-chest clip's role during a crash, despite concerns in some jurisdictions about the potential for neck contact injuries from the clips. This study aimed to investigate the relationship between cross-chest clip use and injury outcomes in children between 0 and 4 years of age.Child passengers between 0 and 4 years of age were selected from the NASS-CDS data sets (2003-2014). Multiple regression analysis was used to model injury outcomes while controlling for age, crash severity, crash direction, and restraint type. The primary outcomes were overall Abbreviated Injury Score (AIS) 2+ injury, and the presence of any neck injury.Across all children aged 0-4 years, correct chest clip use was associated with decreased Abbreviated Injury Scale (AIS) 2+ injury (odds ratio [OR] = 0.44, 95% confidence interval [CI], 0.21-0.91) and was not associated with neck injury. However, outcomes varied by age. In children12 months old, chest clip use was associated with decreased AIS 2+ injury (OR = 0.09, 95% CI, 0.02-0.44). Neck injury (n = 7, all AIS 1) for this age group only occurred with correct cross-chest clip use. For 1- to 4-year-old children, cross-chest clip use had no association with AIS 2+ injury, and correct use significantly decreased the odds of neck injury (OR = 0.49; 95% CI, 0.27-0.87) compared to an incorrectly used or absent cross-chest clip. No serious injuries were directly caused by the chest clips.Correct cross-chest clip use appeared to reduce injury in crashes, and there was no evidence of serious clip-induced injury in children in 5-point harness restraints.

Objective Misuse of child restraint systems is a widespread and long-standing problem impacting risk of injury and death in car crashes. Discomfort has been suggested as a causative factor for misuse, particularly in errors introduced by children while they use the restraints. However, the relationship between comfort and errors in use has never been studied. In this study we examine the reliability and sensitivity of a newly developed observational method for assessing comfort in children in vehicles. We then use this method to examine the relationship between comfort and errors in use of booster seats. Methods A novel method was developed for assessing comfort by counting fidgeting and postural adjustment behaviors to derive a Discomfort Avoidance Behavior (DAB) score. The sensitivity of the DAB score was examined by observing children in four different seating conditions designed as “comfortable” and “uncomfortable” (Part 1). Paired-samples t-tests were used to compare differences in DAB between seating conditions. The reliability of the DAB score was assessed by calculating the intraclass correlation coefficient (ICC) between DAB scores recorded by different researchers. The association between comfort and correctness of use was examined by observing children using booster seats (Part 2). The association between DAB score and number of usage errors was tested using linear regression analysis. Participants were children ages 4–8 years. Fourteen children participated in Part 1 and 15 children in Part 2. Results The DAB score was sensitive to changes in seat condition (p < 0.01), and was repeatable between different researchers (ICC 0.98, 95% confidence interval [CI] 0.954–0.991). Increases in DAB were associated with increases in the number of use errors among children using booster seats (errors in use = 3.89 × DAB − 2.18, p < 0.0001). Conclusion The DAB score is a reliable and valid measure of comfort of children in child restraints but could be improved by incorporating a measurement of postural positioning. Comfort, as characterized by fidgeting and postural adjustment behaviors, is associated with correct use of child restraints. The broader implication is that this confirms ergonomic design of child restraints as important for minimizing errors in use. There is a need for further study of the impact of specific restraint design features on comfort experienced by children.

Syringomyelia (a spinal cord cyst) usually develops as a result of conditions that cause cerebrospinal fluid (CSF) obstruction. The mechanism of syrinx formation and enlargement remains unclear, though previous studies suggest that the fluid enters via the perivascular spaces (PVS) of the penetrating arteries of the spinal cord, and that alterations in the CSF pulse timing and pressure could contribute to enhanced PVS inflow. This study uses an idealised computational model of the PVS to investigate the factors that influence peri-arterial fluid flow. First, we used three sample patient-specific models to explore whether changes in subarachnoid space (SAS) pressures in individuals with and without syringomyelia could influence PVS inflow. Second we conducted a parametric study to determine how features of the CSF pulse altered perivascular fluid, including alterations to timing and magnitude of the peak SAS pressure, the timing of reversal from high to low pressure (diastolic phase), and the area under the pressure-time curve. The model for the patient with syringomyelia had higher net CSF inflow to the PVS than the two subjects without syringomyelia. In the parametric study, only increasing the area under the high pressure region of the SAS pulse substantially increased PVS inflow, when coupled with a temporal shift in arterial and SAS pulses. This suggests that a period of sustained high SAS pressure while arterial diameter is low may increase net CSF pumping into the PVS.

Family day care (FDC) is a child care model used internationally where children are cared for in the homes of educators. FDC educators have regular contact with families and transport children in their care in their own vehicles. The potential of using child care services as a delivery point for information on optimal child car safety practices has previously been established. However, all previous work has focused on formal early childhood education centers. This study examines child restraint practices and knowledge among FDC educators, and the degree to which these services are being used to provide child restraint information to parents, using a descriptive cross-sectional study design. FDC educators (n = 82) and families (n = 142) completed surveys on child restraint knowledge and practices. Educators reported that 96% of children in their care had been transported in vehicles while attending FDC. While 91% said they knew the law regarding child restraint use only 84% reported complying with this leg...

To compare the pattern of injuries to front and rear seat occupants and test the hypothesis that rear seat passengers of different ages sustain different patterns of injury.Patients admitted to a hospital following involvement in a crash in New South Wales (NSW) Australia between 2005 and 2007 were identified using International Classification of Diseases (10th edition [ICD10]) codes. Hospital admissions data were linked with NSW police crash data using probabilistic techniques. The profiles and patterns of injury of front and rear seat passengers were compared. Logistic regression was used to examine how age influenced the pattern of injury among rear seat passengers.Sixty-three percent of hospital admissions were linked with police records. One in 5 passengers were rear seat passengers. There were more unrestrained occupants in the rear (7%) compared to drivers (3%) and front seat passengers (2%). Younger (9-15 years) injured passengers were seated in the rear more often than in the front passenger position and older injured passengers (50 years) were seated more often in the front passenger position than in the rear (15% rear compared to 5% front aged 9-15 years; 22% rear compared to 37% front aged50 years; χ(2), P.001). There were proportionally more fatal injuries among rear seat passengers (10%) than among drivers (5%) and front seat passengers (6%), and the pattern of injury between front and rear passengers also varied. Rear seat passengers had more head and abdominal injuries and fewer thoracic and knee/lower leg injuries than front seat passengers. After adjusting for vehicle age, restraint status, travel speed, and whether or not a fatality occurred in the crash, older (50 years) rear passengers had 6.3 times the odds of sustaining thoracic injuries (95% confidence interval [CI], 2.6-15.0) and lower odds (odds ratio [OR] = 0.4, 95% CI, 0.2-0.9) of sustaining abdominal/lumbar injuries than the youngest occupants (9-15 years).The odds of sustaining a head injury did not vary with age, and the odds of sustaining thoracic, abdominal, or lower extremity injuries did not differ significantly between rear seat passengers aged 16-50 years and 9-15 years.The findings suggest that there is a need for enhanced protection for rear seat passengers, because they have proportionally more fatal injuries than front-seated occupants. The frequency of abdominal injury and the differences between injury patterns observed in front seat passengers suggests a potential benefit from adding abdominal injury risk assessment to rear seat occupant protection test protocols. There is also scope to improve chest protection for older rear seat passengers.

To conduct a process and impact evaluation of a multifaceted education-based pilot program targeting correct use of age-appropriate restraints in a regional setting with a high proportion of Aboriginal and Torres Strait Islander families.The program was delivered in 2010 in 3 early learning centers where 31 percent of the children were of Aboriginal and Torres Strait Islander descent. Each component of the program was assessed for message consistency and uptake. To measure program effectiveness, participating children were matched 1:1 by age, language spoken at home, and annual household income with 71 children from the control arm of a contemporaneous trial. The outcome measure in the control and program centers (a 4-category ordinal scale of restraint use) was compared using ordinal logistic regression accounting for age of the parent.Process evaluation found that though program components were delivered with a consistency of message, uptake was affected by turnover of all staff at one center and by parents experiencing difficulty in paying for subsidized restraints at each of the centers. Impact evaluation found that children from the centers receiving the program had nearly twice the odds of being in a better restraint category than children matched from the control group (adjusted odds ratio [ORadj] = 2.06, 95% confidence interval [CI], 1.09-3.90).This was a pragmatic study reflecting the real-life issues of implementing a program in preschools where 57 percent of families had a low income and turnover of staff was high. Despite these issues, impact evaluation showed that the integrated educational program showed promise in increasing correct use of age-appropriate restraints. The findings from this pilot study support the use of an integrated educational program that includes access to subsidized restraints to promote best practice child restraint use among communities that include a high proportion of Aboriginal and Torres Strait Islander families in New South Wales. Future trials in similar settings should consider offering more support in centers with high turnover of staff and offering alternative methods of payment when families experience financial difficulties in purchasing the subsidized restraints. If proven in larger trials, this approach could reduce death and injuries in child passengers in this vulnerable group.

Objective: Investigate the combined effects of belt geometry, seat substructure, and seat belt pretensioners and load limiters on rear seat occupant injury risk.Methods: An instrumented Hybrid III 5th percentile adult female dummy was subjected to simulated frontal impacts (Δv = 45.8 km/h, peak acceleration = 27.1 g). Testing was conducted on a rear seat of a typical family sedan with modifications allowing for adjustment in upper anchorage position, mounting of an antisubmarining seat pan, and the use of seat belt pretensioners with load limiters.Results: Dummy seated posture had the strongest effect on submarining. Seat belt pretensioners with load limiters reduced head and femur excursion and decreased chest injury measurements but did not prevent submarining. The antisubmarining seat pan, on the other hand, prevented submarining in one case but could not prevent submarining with the dummy in a slouched posture. Upper anchorage position resulting in poor belt geometry was shown to increase both chest injury measures and submarining.Conclusions: The results from this study demonstrate the importance of an upright seated posture and the potential benefits of including adjustable upper anchorages to allow good sash belt fit, antisubmarining seat pans, belt buckles positioned near the seat bight, and seat belts with pretensioners and load limiters for rear seat occupants. These data can be used to inform the design of a system of restraints to reduce injuries to rear seat occupants.

This study aims to investigate the effects of seating posture and seat cushion properties on submarining risk for rear seated children.An instrumented 6-year-old Hybrid III dummy restrained by an inertial-reel 3-point seat belt was subjected to simulated frontal impacts (Δv=28.8 km/h, peak acceleration=16 g). Dummy motion was captured using high-speed digital video. Head acceleration, neck loads, chest deflection, pelvic rotation, and femur displacement were used to assess submarining. Factors investigated included pre-impact seating posture, seat cushion length, stiffness of the seat cushion foam, and the inclination of the seat cushion.The most severe submarining was observed when the dummy was seated in a slouched posture where pelvic rotation was over 3 times greater than in the upright seating posture. Though the standard seat cushion with the dummy seated in the upright posture recorded the lowest values of pelvic rotation and femur displacement, it is unlikely that a child will sit in such a posture. The shortened seat cushion increased femur displacement by 19 percent compared to the standard test seat, but it offers good pre-impact belt position. Submarining occurred in cases where the front edge of the seat collapsed during interactions with the dummy's buttocks.These data suggest that shortening the rear seat cushion alone will not necessarily prevent submarining, but this does allow improved seated posture of the occupant, thus reducing submarining risk. This study has also shown that the collapse of the front edge of the seat cushion is a critical factor in submarining risk.

This study aims to provide population estimates of incorrect restraint use among children aged 0-12 traveling in cars in New South Wales (NSW) and describe the errors occurring in different restraint types.Observations of randomly selected children and restraints were conducted in situ by trained researchers at sites statewide. Observation sites were randomly selected using a multistage stratified sample plan. Restraint use errors were recorded and analyzed by severity of error and restraint type using complex survey analysis techniques.One in two children was incorrectly restrained, and 38 percent in a serious manner. Multiple errors were common (31% of children). Both installation and "securing" errors were common, with installation errors more common in convertible restraints (rearward-facing/forward-facing restraints and forward-facing restraints/booster seats) than single-mode restraints (odds ratio [OR] 4.3; 95% confidence interval [CI] 1.7-10.8). Multiple errors were more common in convertible restraints (OR 3.6; 95% CI 1.9-7.0). The most frequently observed errors were excessive seat belt slack (25 mm), incorrect belt routing, nonengagement of the seat belt buckle, very loose harness (25 mm slack), harness off the shoulder, nonuse of belt guides, sash belt worn under the arm, and very twisted harnesses and belts (2 twists). For rearward- and forward-facing restraints the highest priorities in terms of frequency and degradation in crash protection are errors related to harness use. For booster seat users the most important are those related to correct seat belt and belt guide use. For seat belt users, errors related to correct positioning of the sash belt are key.The results indicate that many errors are currently occurring in the way children are using restraints, as well as problems associated with the way child restraint systems are installed in vehicles. Incorrect use is particularly problematic in convertible restraints (rearward-facing/forward-facing restraints and forward-facing restraints/booster seats). Different priorities, in terms of the frequency and potential degradation in crash protection due to incorrect use for different restraint types, exist and these are important for those designing countermeasures to this problem.

Images obtained from magnetic resonance imaging have helped to ascertain that both the cerebrospinal fluid (CSF) and brain move in a pulsatile manner within the cranium. However, these images are not able to reveal any quantitative information on the physiological forces that are associated with pulsatile motion. Understanding both the pressure and velocity flow field of CSF in the ventricles is important to help understand the mechanics of hydrocephalus. Four separate fluid structure interaction models of the ventricular system in the sagittal plane were created for this purpose. The first model was of a normal brain. The second and third models were pathological brain models with aqueductal stenosis at various locations along the fluid pathway. The fourth model was of a hydrocephalic brain. Results revealed the hydrodynamics of CSF pulsatile flow in the ventricles of these models. Most importantly, it has also revealed the different changes in CSF pulsatile hydrodynamics caused by the various locations of fluid flow obstructions.

This paper describes the construction and validation of a physical model of the human cervical spinal column. The model incorporates a model spinal cord whose deformation may be measured during a simulated impact. The mechanical properties of the model spinal cord and the detailed kinematics of the spinal column were validated against human data in both flexion and extension. The model was then tested in simulated hyperflexion and hyperextension injuries and the cord strains and strain rates measured. In flexion, the strains were found to be in excess of critical values for isolated neural tissue damage. In extension the strains were found to be smaller, and less likely to cause injury in the absence of bony fracture or subluxation.