Biomedical subjects

K B Arbogast

Publications and source records attributed to K B Arbogast.

12 recordsLinked to original sources

PubMed2001

Protecting the child's abdomen: a retractable bicycle handlebar.

A surveillance system in the Emergency Department of a level 1 pediatric trauma center previously identified minor bicycle crashes as a cause of serious child abdominal injury. A discordancy exists between the apparently minor circumstances and serious injuries sustained by child bicyclists who impact bicycle handlebars. The objective of this work was to redesign the bicycle handlebar to reduce the forces transmitted to the child's abdomen during an impact with the handlebars. A retractable handlebar consisting of a spring-mass-damper system was designed to retract and absorb the majority of energy at impact (Patent pending). Because the child remains in contact with the bar after impact, the retracting system also includes a mechanism to damp the outward motion of the handlebar. This prototype will reduce the forces at impact by approximately 50% in a collision similar to those discussed above. A unique methodology of translating research findings into product design produced a novel handlebar that absorbs significant energy that otherwise would be transferred to the child's abdomen when impacting the handlebar.

Abdominal Injuries↗

PubMed2001

Factors influencing pediatric injury in side impact collisions.

BACKGROUND: Side impact collisions pose a great risk to children in crashes, but information about the injury mechanisms is limited. METHODS: This study involves a case series of children in side impact collisions who were identified through Partners for Child Passenger Safety, a large, child-focused crash surveillance system. The aim of the current study was to use in-depth crash investigations to identify injury mechanisms to children in side impact collisions. RESULTS: Ninety-three children in 55 side impact crashes were studied. Twenty-three percent (n = 22) of the children received an Abbreviated Injury Scale (AIS) score > or = 2 (clinically significant) injury. In these 22 children, head (40%), extremity (23%), and abdominal injuries (21%) were the most common significant injuries. Cases that illustrate body region-specific injury mechanisms are discussed. CONCLUSION: The cases revealed that serious injuries, particularly head injuries, occur even in minor crashes, and efforts should be made to make the interiors of vehicles more child occupant friendly. Lower extremity and abdominal injuries occurred because of contact with the intruding door. Design of vehicles to minimize crush should mitigate the occurrence and severity of these injuries.

Abbreviated Injury Scale↗

PubMed2001

Seat belt syndrome in children: a case report and review of the literature.

Characteristic patterns of injury to children in automobile crashes resulting from lap and lap-shoulder belts have been described for many years. These injuries are known as the "seat belt syndrome." We present a typical case of seat belt syndrome involving a 4-year-old boy and review the current literature on the topic, highlighting proposed mechanisms of intra-abdominal and spine injuries. In addition, recent research findings identifying a new pattern of injuries associated with inappropriate seat belt use in young children are reviewed. Emergency physicians must consider these seat belt-related injuries in the initial evaluation of any child involved in a motor vehicle crash who was restrained with the vehicle seat belt.

Abdominal Injuries↗

PubMed2001

The effect of seating position on risk of injury for children in side impact collisions.

The objective of this study was to evaluate the effect of seating position on risk of injury to children in side impact crashes. 5,632 children under age 16 in side impact crashes were enrolled as part of an on-going crash surveillance system which links insurance claims data to telephone survey and crash investigation data. Children seated in the front seat were at higher risk of significant injury than children seated in the rear (OR = 2.2 95% CI (1.2-3.8)). After adjusting for age, restraint use, and vehicle damage, children in the front seat were more likely to be injured (OR 2.6 95% CI (1.1-6.2)) than children seated in the rear when the child was sitting near the side of the impact. These results highlight the importance of evaluating the safety performance of both vehicles and restraint systems for children in side impact crashes.

Accidents, Traffic↗

PubMed2000

Computer crash simulations in the development of child occupant safety policies.

OBJECTIVE: To address the predictability of injury from air bag activation by use of crash simulation software. METHODS: Using current, validated crash simulation software, the effect of air bag activation on injury risk was assessed for the 6-year-old child, both restrained and unrestrained. Results were compared with those for adult occupants in similar crash scenarios. RESULTS: For the unrestrained child passenger, crash simulations predicted serious head, neck, and chest injuries with air bag activation, regardless of crash severity. For the restrained child passenger, crash simulations predicted similar severe injuries for high-severity crashes only. No serious injuries were predicted for unrestrained male adults exposed to air bags or for child passengers restrained in the rear seat for the crash scenarios simulated. CONCLUSIONS: Using current crash simulation software, this study demonstrated that the risk of air bags to school-aged children could be predicted. Our results confirmed the previously identified risks to unrestrained children and provided the first evidence that air bags, in their current design, are not beneficial to restrained children. This study illustrates that computer crash simulations should be used proactively to identify injury risks to child occupants, particularly when limited real-world data are available.

Accidents, Traffic↗

PubMed2000

Assessing child restraint misuse by parental survey.

OBJECTIVE: To determine the extent to which child restraint system (CRS) misuse can be evaluated by parental survey. METHODS: A cross sectional survey was conducted at eight CRS clinics from May to October, 1998. Before CRS inspection, parents were administered a structured interview to identify distinct characteristics of restraint use and misuse. After the interview, a certified child passenger safety technician team independently evaluated the restraint system and identified specific modes of misuse. Parent descriptions of CRS use were compared with observations of the technician and the degree of agreement between the two was assessed for several specific attributes of use. RESULTS: A total of 100 children restrained in convertible CRSs were included in the study. Parents were able to accurately report several aspects of child restraint use-in particular, the attachment and fit of the CRS, the use of the harness clip, and the CRS incline. Parents were less accurate in their characterization of the fit of the child in the CRS. For nearly every item assessed, parents were more accurate in their description of correct compared with incorrect use. CONCLUSIONS: Interview tools can be developed that enable parents to describe aspects of CRS use and that screen for correct CRS use. These tools could be administered by telephone to obtain a more representative estimate of the prevalence of CRS misuse or to screen for CRS misuse. This screening would assist in targeting time consuming and costly CRS clinics to those parents who need them the most.

Cross-Sectional Studies↗

PubMed2000

Misuse of booster seats.

OBJECTIVE: To describe several aspects of booster seat use and misuse in a sample of children attending child safety seat clinics. METHODS: Booster seat practices were assessed at 76 child safety seat clinics held between April 1997 and January 1999 in Pennsylvania and southern New Jersey. At each assessment, a child passenger safety team evaluated the booster seat and identified modes of misuse. RESULTS: Altogether 227 booster seats were observed. Sixty eight per cent (68%) of shield boosters and 20% of belt positioning boosters were misused. Thirty two per cent of the children using a shield booster weighed more than 40 lb (18.1 kg); 68% of children in shield boosters and 63% in belt positioning boosters weighed less than 40 lb. CONCLUSION: This study identified a relatively high rate of booster seat misuse. Shield boosters were more likely to be misused than belt positioning booster seats. Significant numbers of children weighing more than 40 lb were using possibly dangerous shield boosters. The majority of children in this study were less than 40 lb. In this weight range, a convertible child restraint system provides better protection than a booster seat. Booster seat use should only be initiated once the child has completely outgrown their convertible child restraint system.

Humans↗

PubMed2000

Factors influencing pediatric injury in side impact collisions.

Side impacts collisions pose a great risk to children in crashes but information about the injury mechanisms is limited. The heights and weights of children vary widely and as a result, the injury patterns may vary across the pediatric age range. This study involves a case series of children in side impact collisions who were identified through Partners for Child Passenger Safety, a large child-focused crash surveillance system. The aim of the current study was to use in-depth crash investigations to identify injury mechanisms to children in side impact collisions. 93 children in 55 side impact crashes were studied. 23% (n = 22) of the children received an AIS > or = 2 (clinically significant) injury. In these 22 children, head (39%), extremity (22%), and abdominal injuries (17%) were the most common significant injuries. The cases revealed that serious injuries occur even in minor crashes. Cases that illustrate body region-specific injury mechanisms are discussed.

Abbreviated Injury Scale↗

PubMed1999

A fiber-reinforced composite model of the viscoelastic behavior of the brainstem in shear.

Brainstem trauma occurs frequently in severe head injury, often resulting in fatal lesions due to importance of brainstem in crucial neural functions. Structurally, the brainstem is composed of bundles of axonal fibers distinctly oriented in a longitudinal direction surrounded by an extracellular matrix. We hypothesize that the oriented structure and architecture of the brainstem dictates this mechanical response and results in its selective vulnerability in rotational loading. In order to understand the relationship between the biologic architecture and the mechanical response and provide further insight into the high vulnerability of this region, a structural and mathematical model was created. A fiber-reinforced composite model composed of viscoelastic fibers surrounded by a viscoelastic matrix was used to relate the biological architecture of the brainstem to its anisotropic mechanical response. Relevant model parameters measured include the brainstem's composite complex moduli and relative fraction of matrix and fiber. The model predicted that the fiber component is three times stiffer and more viscous than the matrix. The fiber modulus predictions were compared with experimental tissue measurements. The optic nerve, a bundle of tightly packed longitudinally arranged myelinated fibers with little matrix, served as a surrogate for the brainstem fiber component. Model predictions agreed with experimental measures, offering a validation of the model. This approach provided an understanding of the relationship between the specific biologic architecture of the brainstem and the anisotropic mechanical response and allowed insight into reasons for the selective vulnerability of this region in rotational head injury.

Animals↗

PubMed1998

Material characterization of the brainstem from oscillatory shear tests.

Traumatic damage to the brainstem occurs frequently when the brain skull complex experiences injurious loading especially during those traumatic situations that produce diffuse axonal injury (DAI). DAI has been shown to be dependent on load direction and correlated with regional tissue deformation in response to rotational inertial loads. Possible mechanisms for the selective vulnerability of the brainstem are (1) the geometry of the central nervous system is responsible for producing high tissue strains in these regions, (2) regional differences in overall material stiffness result in larger deformations at these sites, and (3) the anisotropic mechanical properties of these regions lead to a sensitivity to the rotational load direction and magnitude. This paper investigates the latter two hypotheses by performing oscillatory shear tests on adult porcine brainstem in three mutually perpendicular directions. The complex shear moduli were calculated over a range of frequencies (20-200 Hz), for three levels of peak engineering strain (2.5%, 5.0%, and 7.5%). The directional data demonstrated that the brainstem exhibits significant transversely isotropic behavior. Both components of the complex modulus in which the axonal fibers are oriented parallel to the plane of shear but transverse to the shear direction were significantly higher than those of the other two, mutually indistinguishable test cases across the range of strains tested. By comparison with similar tests on cerebral tissue, these data demonstrated that the brainstem displays a stiffer biomechanical response. These differences were present for both components of the complex shear modulus and were greater as the magnitude of the applied strain increased. The regional stiffness and anisotropic response of the brainstem coupled with its location as a narrow bridge between CNS regions interact to result in the selective vulnerability of this region in rotational loading.

Animals↗

PubMed1997

A high-frequency shear device for testing soft biological tissues.

Accurate mechanical property data obtained at large shear deformations and high frequencies are a fundamental component of realistic numerical simulations of soft tissue injury. Although many commercial systems exist for testing shear properties of viscoelastic materials with properties similar to soft biological tissue, none are capable of determining properties at high loading rates necessary for modeling soft tissue injury. Previous custom shear testing systems, though capable of high-frequency loading, indirectly measure tissue properties by using analytical corrections for inertial effects. To address these limitations, a new custom designed oscillatory shear testing apparatus (STA) capable of testing soft biological tissues in simple shear has been constructed and validated. Through a proper selection of sample thickness, direct measurement of material properties at high frequencies is achieved mechanically without analytical inertial adjustments. The complex shear modulus of three mixtures of silicone gel with viscoelastic properties in a range similar to soft biological tissue was characterized in the STA over a dynamic frequency range of 20-200 Hz and validated with a commercially available solids rheometer. The frequency-dependent complex shear modulus measurements of the STA were within 10% of the rheometer measurements for all mixtures over the entire frequency range tested. The STA represents substantive improvement over current shear testing methods by providing direct measurement of the shear behavior of soft viscoelastic material at high frequencies. Mechanical property data gained from this device will provide a more realistic basis for numerical simulations of biological structures.

Brain↗

PubMed1994

Improved assessment of lumbar vertebral body strength using supine lateral dual-energy x-ray absorptiometry.

Clinical and biomechanical investigations indicate that assessment of vertebral body bone mineral density (BMD) by anteroposterior dual-energy x-ray absorptiometry (DXA) is a useful index of vertebral body strength and fracture risk in osteoporosis. However, inclusion of non-force-bearing and small-force-bearing mineralized structures, such as the posterior elements and aortic calcifications, in the measurement of anterior BMD obscures the assessment of vertebral body mass by this technique. Indeed, such interference is particularly severe in the presence of posterior element degeneration or previous spinal surgery. Recent anatomic studies illustrate that the lateral view provides unobstructed visualization of the L3, L4, and possibly L2 vertebral bodies, suggesting that supine lateral BMD may more accurately assess vertebral body fracture risk. We evaluated this hypothesis in a blinded using human cadaver spines to compare the value of supine lateral and anteroposterior BMD in assessing vertebral body fracture force, average compressive stress, maximum stored strain energy, and strain at failure. Both measures of BMD significantly correlate with these biomechanical measures. However, statistical comparison of the methods using multiple and stepwise regression reveals that supine lateral BMD provides a better assessment of the vertebral body fracture properties than anteroposterior BMD. The enhanced predictive value of supine lateral BMD occurs because of the variable contribution of posterior element mineral to the anteroposterior BMD measurement. Evaluation to test the utility of supine lateral BMD for the assessment of fracture risk and a fracture threshold in patients with osteoporosis is therefore recommended.

Absorptiometry, Photon↗