Recreating the Feel of the Human Chest in a CPR Manikin via Programmable Pneumatic Damping

It is well known that the human chest exhibits a strong force displacement hysteresis during CPR, a stark contrast to the non hysteretic behavior of standard spring manikins. We hypothesize that individuals with experience performing CPR on humans would perceive a manikin with damping as more realistic and better for training. By analyzing data collected from chest compressions on real patients, we created a dynamic model that accounts for this hysteresis with a linear spring and a one-way variable damper, and we built a new high-fidelity manikin to enact the desired force displacement relationship. A linkage attached to the chest plate converts vertical compression motions to the horizontal displacement of a set of pneumatic dashpot pistons, sending a volume of air into and out of the manikin through a programmable valve. Position and pressure sensors allow a microcontroller to adjust the valve orifice so that the provided damping force closely follows the desired damping force throughout the compression cycle. Eight experienced CPR practitioners tested both the new manikin and an identical looking standard manikin; the manikin with damping received significantly higher ratings for haptic realism and perceived utility as a training tool

Traumatic brain injury thresholds in the pre-adolescent juvenile

Traumatic brain injury (TBI) continues to be a major health epidemic, with an annual incidence in the United States in excess of 1.5 million per year, leading to 50,000 fatalities and 3.7 million people living with long-term disability from TBI. TBI is particularly devastating to the young. In countries around the globe, motor vehicle crashes are the leading cause of death for all children and traumatic brain and skull injuries are the most common serious injuries sustained by children in motor vehicle crashes. While the age-dependent tolerance of the infant and toddler have been investigated no information exists on the tolerance of pre-adolescent brain to injury. The research described herein provides critical experimental and computational TBI injury tolerance information for the pre-adolescent juvenile age group. In Chapter 2, we describe the development of a pre-adolescent TBI animal model that produces injury relevant to the human including diffuse axonal injury, subarachnoid and subdural hemorrhage, and secondary brain injury. We compare results with data from infant and toddler animals and propose an empirical scaling relationship to estimate velocity and acceleration tolerance. In Chapter 3, we develop a Finite Element Model (FEM) of pre-adolescent animal based upon a validated model from the younger animals, and determine the strain threshold for TBI in the pre-adolescent and compare it to the strain threshold of the infant. In Chapter 4, we develop an ultra high resolution finite element model with element edge length in the sub millimeter range and high geometric fidelity to both internal and external brain structures. We then use this high resolution model to investigate the effects of material heterogeneity on strain and injury prediction. Finally, in Chapter 5 we discuss the implications of our research in light of our long-term goal to support the development of human FEM brain models that can be coupled with an ATD and used to evaluate safety system design

Comparative Performance of Forward-Facing Child Restraint Systems on the C/FMVSS 213 Bench and Vehicle Seats

<div><p><b>Objective:</b> The objective of this study was to evaluate the fidelity of the C/FMVSS 213 test bench, by comparing the dynamic performance of forward-facing child restraint systems (FFCRS) mounted on the C/FMVSS 213 sled bench versus mounted on a selection of production vehicle seats.</p><p><b>Methods:</b> The C/FMVSS 213 bench or one of 3 second-row original equipment manufacturer vehicle seats was mounted to the deck of acceleration crash sled. An FFCRS with a restrained anthropomorphic test device (ATD) was secured by 3-point belt (3-PT) or LATCH lower anchor (LLA) on the C/FMVSS 213 bench or vehicle seat, with or without a tether. The sled was then exposed to a 48 km/h acceleration pulse. Three unique make and model vehicle seats and FFCRS were tested. Fifty-three sled tests were performed.</p><p><b>Results:</b> When FFCRS were secured with LLA and no tether, little difference between the vehicle seats and 213 bench was observed. Similarly, when FFCRS were affixed with 3-PT and no tether, few kinematic variable differences achieved statistical significance; chest resultant acceleration was, on average, 9.1 <i>g</i> (SD = 6.6, <i>P</i> =.006) higher on the vehicle seats compared to the bench, as was CRS seatback excursion (difference [Δ] of 39.8 mm, SD = 32.7, <i>P</i> =.011) and ATD knee excursion (Δ = 36.4 mm, SD = 12.0, <i>P</i> < .001). However, when the tether was added to either the 3-PT or LLA attachment methods, the difference between the bench and vehicle seats was more pronounced. ATD kinematic measures such as head resultant acceleration (Δ = 14.6 <i>g</i>, SD = 7.2, <i>P</i> <.001) and pelvis resultant acceleration (Δ = 8.6 <i>g</i>, SD = 6.0, <i>P</i> =.005) were higher on the vehicle seats compared to the bench, as were the injury metrics for head and chest injury: ΔHIC15 = 162.2 (SD = 87.4, <i>P</i> =.001) and ΔChest 3 ms clip = 5.5 <i>g</i> (SD = 6.2, <i>P</i> =.040). Of note, CRS (Δ = 62.8 mm, SD = 32.7, <i>P</i> =.000) and ATD head (Δ = 66.3 mm, SD = 30.9, <i>P</i> =.000) and knee (Δ = 46.9 mm, SD = 25.8, <i>P</i> =.001) forward excursion were all higher on the vehicle seats compared to the bench in 3-PT with tether condition.</p><p><b>Conclusions:</b> Without the tether attached, we observed few kinematic and kinetic differences between the vehicle seat and the C/FMVSS 213 bench, suggesting that the bench is an adequate surrogate for the vehicle seat in this condition. With the tether attached, we found significant differences between the C/FMVSS 213 bench and vehicle seats, suggesting that the fidelity of the bench could be improved in the tethered mode. When differences were statistically significant, excursion and injury metrics were generally greater on the vehicle seats than on the C/FMVSS 213 bench.</p></div

Pediatric Occupant—Vehicle Contact Maps in Rollover Motor Vehicle Crashes

<div><p><b>Objective:</b> Rollover crashes account for more than 33% of all motor vehicle–related fatalities and have the highest fatality risk of all crash types, at 1.37% in the United States. There is increased awareness of the high fatality rate associated with this crash type, but there is very limited pediatric-specific data related to rollover crashes in the United States. Recent focus on rollover mitigation has resulted in implementation of countermeasures, making it important to evaluate injury causation for child occupants in rollover crashes with a more current data set.</p><p><b>Methods:</b> We queried the Crash Injury Research and Engineering Network (CIREN) from case years 1998 through 2013. Rollover crashes for passenger vehicles of model year 1998 or newer with at least one restrained occupant (excluding drivers) between 0 and 19 years of age were included. Vehicle-involved physical component and occupant–vehicle contact maps were developed with the CIREN data set.</p><p><b>Results and Conclusions:</b> Of the 20 CIREN cases that met the inclusion criteria, 15 had one or more injuries attributed to contact with some part of the vehicle structure. The CIREN analyses revealed that the head was the most common seriously injured body region, primarily due to contact with the roof side rail and/or vehicle interior. This finding was true for both adolescents and younger pediatric passengers in outboard seating positions. Fifty percent of head injury causation scenarios involving the vehicle interior had component intrusion of 20+ cm at the point of contact. Further exploration of pediatric rollover injury mechanisms using computational modeling and real-world testing is recommended in order to improve upon current mitigation strategies.</p></div