Association between seatbelt sign and internal injuries in the contemporary airbag era: A retrospective cohort study.

BACKGROUND: Literature predating routine availability of airbags reported an association between seatbelt signs and internal injuries. We measured this association among patients involved in motor vehicle crashes (MVCs) with airbag deployment. METHODS: We conducted a retrospective cohort study by chart review of all MVC patients presenting to our Emergency Department (ED) during 1 January 2008-30 September 2015. We included all adult MVC patients in the driver or front passenger seats with both shoulder and lap seatbelts and airbag deployment. Two trained chart abstractors recorded data regarding restraints and airbag deployment. We obtained all other data via electronic medical record abstraction including demographics, injuries, and survival. We compared the prevalence of cervicothoracic and intra-abdominopelvic injuries between patients with a documented seatbelt sign versus no seatbelt sign using a logistic regression model. RESULTS: Of 1379 MVC patients, 350 met inclusion criteria. Of these, 138 (39.4%) had a seatbelt sign. The prevalence of cervicothoracic injury was higher among subjects with a documented seatbelt sign (54.3% versus 42.9%, p=0.036) Seatbelt sign predicted cervicothoracic injury with a positive likelihood ratio of 1.3 (95% CI 1.0-1.7) and negative likelihood ratio of 0.8 (95% CI 0.7-1.0). The odds ratio of cervicothoracic injury among patients with a seatbelt sign versus no seatbelt sign was 1.58 (95% confidence interval 1.02-2.46) in the logistic regression model. There was no association between seatbelt sign and intra-abdominopelvic injury (p=0.418). CONCLUSIONS: In the setting of airbag deployment, there is an association between seatbelt sign and cervicothoracic injury but not intra-abdominopelvic injury.

Seatbelt use and seat preference among pregnant women in Sapporo, Japan, in 2013.

AIM: This study was performed to determine the rate of pregnant occupants in motor vehicle accidents (MVA) and the frequency of seatbelt use in pregnancy in Japan. METHODS: A questionnaire survey was conducted at seven centers located in Sapporo, targeting all 3952 women in gestational weeks 35-37 during the study period between June 2013 and January 2014. Information was collected on parity, driver's license, seatbelt use, seat preference, carrying Mother and Child Health Handbook when going out, and experience of occupant MVA during current pregnancy. Women who reported always using a seatbelt were classified as always seatbelt users (ASU). RESULTS: A total of 2420 women who were given questionnaires provided responses (response rate, 61%). Seventy women (2.9%) reported having experienced an occupant MVA during the current pregnancy. MVA rate was significantly lower for ASU than non-ASU (2.6% [55/2097] vs 4.6% [15/323], respectively, P < 0.0001), and for ASU women preferring the rear seat than for other women (1.3% [6/451] vs 3.3% [64/1969], respectively, P = 0.0282). MVA rate tended to be lower for women preferring the rear seat than the front seat (1.7% [10/575] vs 3.3% [60/1845], respectively, P = 0.0637). The number of ASU, 94% (2286/2420) before pregnancy, decreased significantly to 87% (2097/2420) after the current pregnancy (P < 0.0001). CONCLUSION: The careful attitude of pregnant women toward driving safety may be associated with reduced risk of MVA in pregnancy. There is a need for an intensified campaign to promote seatbelt use among pregnant women.

Frontal NCAP performance and field injury over 40 years.

OBJECTIVES: Vehicle and occupant responses in 35 mph NCAP tests were determined for small-midsize passenger cars grouped around model year (MY) 1980, 1990, 2000, 2010 and 2020. A baseline was established with 1980 vehicles not designed for NCAP. The results of four decades of vehicles designed for NCAP were compared to the baseline. The study also determined the risk for serious injury (MAIS 3 + F) by vehicle model year (MY) using 1989-2015 NASS and 2017-2020 CISS. It explored safety trends in frontal crashes over 50 MYs of vehicles. METHODS: The 1980 baseline group was established with 10 1979-1983 MY passenger cars weighing <1,500 kg. Four decades of vehicle crash tests from five manufacturers established trends in vehicle dynamics and dummy responses over four decades of vehicles designed for NCAP. Triaxial acceleration of the head and chest were reanalyzed for each test to have a consistent set of responses over five decades. The risk for serious injury (MAIS 3 + F) to the driver and front passenger was determined by vehicle MY using 1989-2015 NASS and 2017-2020 CISS with belted and unbelted drivers and right-front passengers. The data was sorted in four MY groups 1961-1989 MY, 1990-1999 MY, 2000-2009 MY and 2010 MY-2021 MY. The risk for MAIS 3 + F injury was determined with standard errors using weighted data. RESULTS: The 1980 NCAP tests brought about changes in vehicle structures and occupant restraints by 1990; however, HIC15 and 3 ms chest acceleration have not changed much the past 20 years since the use of advanced airbags and seatbelts with pretensioner and load-limiters. For the driver, HIC15 dropped 40 ± 19% from the 1980 to 1990 NCAP tests and dropped further to 76 ± 32% in 2020. The percentage drops after 1990 were not statistically significant. The driver 3 ms chest acceleration dropped 18 ± 5% from 1980 to 1990 and plateaued with 22 ± 6% in 2020. For the front passenger, HIC15 dropped 68 ± 52% from the 1980 to 1990 NCAP tests and plateaued at 71 ± 49% in 2020. The passenger 3 ms chest acceleration dropped 13 ± 5% from 1980 to 1990 and has fluctuated with minimal change. Injury risks based on responses show the same initial drop in 1990 and have remained essentially constant. Nothing meaningful has changed in dummy responses in the past 20 years of NCAP testing. The field data found the belted driver MAIS 3 + F risk was 1.66 ± 0.37% in 1961-1989 MY vehicles and 1.39 ± 0.33% in 2010-2021 MY vehicles. For belted right-front passengers, the risk was 1.52 ± 0.39% in 1961-1989 MY vehicles and 1.42 ± 0.46% in 2010-2021 MY vehicles. The field data shows no meaningful change in injury risk in 50 MYs of vehicles. NCAP involves 35-40 mph delta-V, which represents a small fraction, 0.33%, of belted occupant exposure and only 8.6% of severe injury based on 1994-2015 NASS. CONCLUSIONS: The NCAP test lacks field relevance. Manufacturers are merely "tuning" the restraint systems for star ratings without meaningful changes in field injury risks the past 20 years. There are disbenefits of "tuning" safety for a single, high-severity crash when most of the severe injury occurs in lower severity crashes. NHTSA should reevaluate plans to change the dummy to Thor and add BrIC injury criteria to assess NCAP responses. These changes would cause manufacturers to further "tune" structures, restraints and interiors without meaningful effects in real-world crashes.

Analysis of the lack of restraint with and without belt pretensioning in 40.2 km/h rear impacts.

OBJECTIVE: In rear impacts, the seat and seatbelt are intended to provide occupant restraint and maintain the occupant on the seat with favorable kinematics and low biomechanical responses. This study analyzes the lack of restraint provided by lap-shoulder belts in rear impacts with and without pretensioning and offers thoughts on ways to provide early restraint by seatbelts. METHODS: Rear sled tests were conducted at 40.2 km/h (25 mph) delta V with a lap-shoulder belted, instrumented 50th Hybrid III. The dummy instrumentation included head, chest and pelvis triaxial acceleration and upper and lower neck triaxial loads and moments. Lap and shoulder belt loads were measured. High-speed video recorded different views of the occupant kinematics. In the first series, two sled tests were conducted with a Ford F-150 driver seat. One test was with the standard lap-shoulder belts only and a second with buckle pretensioner activation. In the second series, three matched tests were conducted with a Ford Escape driver seat. One test was with the lap-shoulder belts only, a second with retractor and anchor pretensioning and a third with only retractor pretensioning. The analysis included occupant kinematics, lap-belt movement and estimation of the load on the occupant's torso. The load was the sum of force on the upper and lower torso. The upper torso mass was 30.8 kg (67.8 lb) based on GEBOD data for the 50th Hybrid III. It was multiplied by the resultant chest acceleration to calculate the upper torso force. The lower-torso mass was 30.9 kg (68.0 lb). It was multiplied by the resultant pelvic acceleration to calculate the lower torso force. The total load on the seatback was the sum of the upper and lower torso force. The change in angle (θ) of the lap belt was determined by video analysis. The angle θ was from the horizontal up to a line through the lap-belt webbing. Ways to provide early lap-belt restraint were considered. RESULTS: The rear sled testing at 40.2 km/h (25 mph) showed that the seatbelt provided essentially no restraint of the rearward movement of the occupant. The seat provided essentially all of the rearward restraint with and without pretensioning. There was minimal lap belt load in the series with the dual recliner Escape seat, except for a spike caused by pretensioning. There was more seat deformation in the tests with the single-side recliner F-150 seat. There were higher belt loads. The lap belt limited the lifting of the hips and thighs with essentially no rearward restraint of the occupant. Tension in the lap belt did not relate to restraint of rearward movement of the occupant. Seatbelts provided forward restraint of the occupant during rebound with the belts providing noticeable deceleration of the chest and pelvis. Concepts were considered to provide early lap-belt restraint. One involved a rear pretensioner that dynamically moves the lap-belt anchor forward and upward while tightening the belts in a rear impact. This provides a lap-belt angle greater than θ = 90 deg before occupant movement. With this geometry, the lap belt restrains rearward movement of the occupant and pulls the hip down early in a rear impact. CONCLUSION: Seatbelts and pretensioners were designed for occupant restraint in frontal crashes, so it is not a surprise they do not provide much restraint of an occupant in rear impacts up to 40.2 km/h (25 mph). The lack of early lap-belt restraint is due to the unfavorable belt angle from the anchors over the hip. A concept is discussed that dynamically moves the anchors in rear impacts to provide early belt restraint.

Effect of naturalistic seating postures and seatbelt routing on booster-seated Q6 ATD kinematics and kinetics in frontal impacts.

RESEARCH QUESTIONS / OBJECTIVE: Test protocols evaluate restraint performance with pediatric ATDs placed in an ideal seating posture. However, real-world evidence suggests that ideal test conditions do not always reflect actual occupant positions. Prior studies have also shown that booster seat designs affect the position of the seatbelt around the child. Occupants in naturalistic seating postures, coupled with potentially unfavorable seatbelt positions, could result in adverse kinematics and kinetics in a crash. Therefore, the aim of this study was to quantify the effect of different naturalistic seating postures on the response of the Q6 ATD restrained on boosters with varying initial static belt fit in a frontal impact. METHODS/DATA SOURCES: The Q6 ATD was positioned on two booster seats of similar design but varying static belt fit metrics in three seating postures: reference, leaning forward, and leaning inboard. These booster seats were chosen from extensive belt fit studies on human volunteers and ATDs, and were defined as follows:The booster-seated ATD was restrained on the simulated Consumer Reports test buck (2010 Ford Flex 2nd row seat) with a front blocker plate using a 3-point lap-shoulder belt with a retractor and pretensioner. The sled environment was subjected to the FMVSS 213 frontal impact pulse, and each booster and seating posture was evaluated twice (n = 12 sled tests). Kinematic and kinetic measures were recorded. A linear regression analysis was conducted across postures on each booster. Further, a paired t-test analysis was conducted across booster seats for each seating posture. RESULTS: Across seating postures, the reference posture exhibited similar or higher kinematic and kinetic metric values compared to the leaning forward and leaning inboard postures on both boosters. However, both leaning forward (Booster A = 279.5 ± 21.6 mm; Booster B = 298.8 ± 1.5 mm) and leaning inboard (Booster A = 308.7 ± 1.1 mm; Booster B = 331.4 ± 8.5 mm) postures generally resulted in greater head excursion than the reference posture (Booster A = 285.0 ± 16.9 mm; Booster B = 288.1 ± 1.5 mm), indicating greater potential for head contact. Between boosters, Booster A resulted in significantly lower head 3 ms clip acceleration (p = 0.0026), HIC15 (p = 0.0008), upper neck tensile force (Fz)(p = 0.0057), chest 3 ms clip acceleration (p = 0.0013), and right abdominal pressure (p = 0.0163), and significantly higher left ASIS force (Fx)(p = 0.0150) and left (p = 0.0489) and right (p = 0.0088) ASIS moment (My) than Booster B. Upper neck tensile forces on Booster B crossed the 20% and 50% thresholds for AIS3 + injury. Lower abdominal pressure and higher ASIS forces and moments on Booster A suggest that the lap belt loaded the ASIS appropriately, and hence, relatively better kinematics than Booster B. SIGNIFICANCE OF RESULTS: This study shows that booster design affects static belt fit which can have an effect on dynamic crash performance and assessment criteria. By connecting static belt fit to dynamic performance, these effects may have the potential to help guide booster seat design.

Evaluations of pretensioner activation in rear impacts.

OBJECTIVE: Occupant kinematics and biomechanical responses are assessed with and without pretensioning of normally seated and out-of-position front-seat occupants in rear sled tests. The results are compared to recent studies. METHODS: Three series of rear sled tests were conducted at 24 and 40 km/h with a 2001 Ford Taurus. Series I consisted of two sled tests with a lap-shoulder belted 50th Hybrid III in the driver seat. Series II included four sled tests with a lap-shoulder belted 50th Hybrid III in both front seats. Two soft foam blocks were added, one was placed on the chest centerline under the shoulder belt and one on the pelvis under the lap belt providing additional webbing. Series III consisted of 8 runs and 16 ATD tests to assess the effect of pretensioning with out-of-positioned (OOP) occupants. The biomechanical responses were normalized with Injury Assessment Reference Values (IARV) for head, neck and chest. RESULTS: The ATD kinematics and biomechanical responses were similar in the yielding phase when the occupant was normally seated with and without pretensioning. The rebound displacement was greater with pretensioning in the 40 km/h tests due to the shoulder belt slipping off the shoulder. The hip displacement was similar, irrespective of pretensioning. All biomechanical responses were below IARVs. The highest response was for lower neck extension. The normalized response was at about 32% for the 24 km/h tests, irrespective of pretensioning. It was up to 59% in the 40 km/h tests with pretensioning. With the OOP occupants, there were no differences in the kinematics and biomechanical response with pretensioning. CONCLUSIONS: Testing of the effect of retractor pretensioning with out-of-position occupants and additional belt webbing in moderate to high-speed rear sled tests shows no effect on occupant kinematics and biomechanical responses. The displacement of the hips in a rear impact depends on the compliance of the seatback and amount of pocketing, the stiffness of the seat frame limiting rearward rotation, and the dynamic friction between the occupant and the seatback.

Influence of retractor and anchor pretensioning on dummy responses in 40 km/h rear sled tests.

OBJECTIVE: This study compared dummy kinematics and biomechanical responses with and without retractor pretensioning in a severe rear sled test. It compliments an earlier study with buckle pretensioning. METHODS: Three rear tests were run at 40 km/h (25 mph) delta V with a lap-shoulder belted Hybrid III 50th male dummy on a 2013-18 Ford Escape driver seat and belt restraint. One test was with the lap-shoulder belts only, a second with retractor and anchor pretensioning and a third with only retractor pretensioning. The head, chest and pelvis were instrumented with triaxial accelerometers. The upper and lower neck, thoracic spine and lumbar spine had transducers measuring triaxial loads and moments. Lap belt load was measured. High-speed video recorded different views of the dummy motion. Dummy kinematics and biomechanical responses were compared to determine the influence of retractor belt pretensioning. RESULTS: The dummy kinematics and biomechanical responses were essentially similar with and without retractor or retractor and anchor pretensioning in rear sled tests. There was an initial spike in lap belt load with pretensioning, but it did not result in different dummy head, neck or chest responses. In the tests, the dummy moved rearward away from the shoulder belt. The belts were tightened with the rapid pull on the webbing by pretensioning. The dummy loaded the seat, which yielded rearward restraining its motion. There was no significant effect of pretensioning on the dynamics of the dummy until late in rebound. CONCLUSIONS: There were no significant differences in dynamics of the Hybrid III with and without retractor or retractor and anchor pretensioning in a 40 km/h (25 mph) rear sled test. Belt pretensioning did not influence biomechanical responses in the rear impact because the seat supported the dummy.

Child injuries in land vehicles that do not require restraints.

The goal of this study was to determine the injury profiles of Canadian children who presented to the Emergency Department from 1990 to 2016 due to an injury caused while traveling in a form of land transportation that did not require child restraint. A case series was conducted using data from the electronic Canadian Hospitals Injury Reporting and Prevention Program (eCHIRPP). Children who were injured while travelling on land transportation for which child restraint is not required, who presented to a Canadian Emergency Department that participates in eCHIRPP between April 1, 1990 to August 29, 2016, were included. Overall, 1856 children sustained 2139 injuries (mean age: 9.8 years (SD 4.5), 45.5% male). The majority of children were injured on a school bus (49.3%). The most commonly injured body part was the head or neck (52.6%). The most common type of injury was a superficial or open wound (33.1%), followed by traumatic brain injury (19.3%). Overall, 39.4% of injuries required no treatment in hospital. Overall, approximately 70 children presented to eCHIRPP EDs per year on a land transportation vehicle that does not require restraints. Biomechanical studies are needed to improve safety on land transportation vehicles that do not require seatbelts.

Side impact motor vehicle crashes: driver, passenger, vehicle and crash characteristics for fatally and nonfatally-injured rear-seated adults.

BACKGROUND: Most studies of rear-seated occupants have focused on or included pediatric occupants which may not translate to adults. This study examines passenger, driver, vehicle and crash characteristics for rear-seated adult occupants involved in side crashes. METHODS: The National Automotive Sampling System General Estimates System (NASS/GES) for calendar years 2011-2014 was used with accompanying weights to examine the occupant, vehicle and crash characteristics associated with injury in rear-seated adults (n = 395,504) involved in a side crash. A weighted subpopulation analysis includes occupants travelling in a vehicle with an IIHS safety rating (n = 39,208), which was used to control for vehicle safety. Statistical analysis used Chi-square tests and multilevel multivariable logistic regression. Unadjusted and adjusted odds ratios (ORs) are reported with 95 % confidence intervals (95 % CIs). RESULTS: Rear-seated occupants on the same side as the crash impact were more likely to be severely/fatally injured than occupants seated on the opposite side (Multivariable adjusted OR: 2.54, 95 % CI: 2.31-2.79), as were those in angle crashes (Multivariable adjusted OR: 10.85, 95 % CI: 9.24-12.73). Rear-seated occupants of belted drivers were 3.28 times more likely to be belted compared to rear-seated occupants of an unbelted driver. In a subpopulation analysis of all same-side crashes, unrestrained occupants were 5.96 times more likely to be severely/fatally injured compared to restrained occupants. CONCLUSION: Restraint use was protective for rear-seated adult occupants involved in side crashes, including those in same-side crashes. Angle and same-side crashes are associated with increased injury severity.

Involving fathers in teaching youth about farm tractor seatbelt safety--a randomized control study.

PURPOSE: Farm youth continue to experience high rates of injury and deaths as a result of agricultural activities. Farm machinery, especially tractors, is the most common cause of casualties to youth. A Roll-Over Protection Structure (ROPS) along with a fastened seatbelt can prevent almost all injuries and fatalities from tractor overturns. Despite this knowledge, the use of seatbelts by farmers on ROPS tractors remains low. This study treats farm safety as a family issue and builds on the central role of parents as teachers and role models of farm safety for youth. METHODS: This research study used a longitudinal, repeated-measures, randomized-control design in which youth 10-19 years of age were randomly assigned to either of two intervention groups (parent-led group and staff-led group) or the control group. RESULTS: Fathers in the parent-led group were less likely to operate ROPS tractors without a seatbelt compared with other groups. They were more likely to have communicated with youth about the importance of wearing seatbelts on ROPS tractors. Consequently, youth in the parent-led group were less likely to operate a ROPS tractor without a seatbelt than the control group at post-test. CONCLUSIONS: This randomized control trial supports the effectiveness of a home-based, father-led farm safety intervention as a promising strategy for reducing youth as well as father-unsafe behaviors (related to tractor seatbelts) on the farm. This intervention appealed to fathers' strong motivation to practice tractor safety for the sake of their youth. Involving fathers helped change both father as well as youth unsafe tractor-seatbelt behaviors.

The impact of seat-belts in limiting the severity of injuries in patients presenting to a university hospital in the developing world.

BACKGROUND: Road traffic injuries are major public health problems and a leading cause of death and injury around the world. Approximately 1.2 million people are killed each year in road crashes worldwide, with up to 50 million more injured. Over 95% of these deaths and injuries occur in the low- and middle-income countries of the world. The aim of this study is to evaluate the impact of the use of seat-belts in reducing the severity of injuries from road traffic crashes and to determine the compliance and awareness of the importance of the use of seat-belts among Nigerian motorists. PATIENTS AND METHODS: The injury patterns and outcome of care in 140 patients who were seen at the emergency department of our tertiary hospital were evaluated. Initial care and resuscitation was carried out on all patients using the advanced trauma life support protocol. RESULTS: A total of 81 (57%) patients used seat-belts, while 59 (42.1%) did not. Nineteen (13.6%) patients died as a result of their injuries; 4 (21.1%) of these had used seat-belts, while 15 (79%) had not (P = 0.001). The mortality rate of 79% for patients who did not use seat-belt was statistically significant. CONCLUSIONS: The seat-belt is an effective safety tool that not only saves lives, but also significantly reduces the severity of the injury that a vehicle occupant may have sustained if they were not wearing the device. More public enlightenment is needed to increase the awareness and compliance of use of seat-belts among Nigerian motorists.

Erros de utilização de assentos de segurança infantil por menores de 4 anos / Child safety seat usage errors in under-4s

OBJETIVO: Analisar erros de utilização de assentos de segurança infantil por crianças matriculadas em creches e fatores relacionados. MÉTODOS: Estudo observacional transversal de coleta de dados prospectiva e eixo analítico retrospectivo. RESULTADOS: Um total de 42,7% das crianças apresentava erros de utilização. O modelo de regressão logística evidenciou maiores chances de erros na presença de duas ou mais crianças no veículo (odds ratio = 5,10, p = 0,007) e menores níveis de escolaridade e renda dos pais (renda e escolaridade médias: odds ratio = 7,00, p = 0,003; renda e escolaridade baixas: odds ratio = 3,40, p = 0,03). CONCLUSÃO: Os dados são coerentes com publicações internacionais.

OBJECTIVE: To analyze child safety seat usage errors among children enrolled at daycare. METHODS: This was a cross-sectional, observational study with prospective data collection and a retrospective analytical axis. RESULTS: Overall, 42.7% of the children studied were in incorrectly used seats. A logistic regression model showed that the likelihood of usage errors was higher if there were two or more children in the vehicle (odds ratio = 5.10, p = 0.007) and was dependent on parents' educational level and income (medium income and educational level: odds ratio = 7.00, p = 0.003; low income and educational level: odds ratio = 3.40, p = 0.03). CONCLUSION: The results of this study are in line with findings reported in international publications.