Methods for determining pediatric thoracic force-deflection characteristics from cardiopulmonary resuscitation.
The Children's Hospital of Philadelphia, 3535 Market Street, 11th Floor, Philadelphia, PA 19104, USA. Stapp car crash journal
Accurate pediatric thoracic force and deflection data are critical to develop biofidelic pediatric anthropomorphic test devices (ATDs) used in designing motor vehicle safety systems for child occupants. Typically, post-mortem human subject (PMHS) experiments are conducted to gather such data. However, there are few pediatric PMHS available for impact research, therefore novel methods are required to determine pediatric biomechanical data from children. In this study, we have leveraged the application of chest compressions provided in the clinical environment during pediatric cardiopulmonary resuscitation (CPR) to collect this fundamental data. The maximum deflection of the chest during CPR is in the range of chest deflections in PMHS impact experiments and therefore CPR exercises the chest in ways that are meaningful for biofidelity assessment. Thus, the goal of this study was to measure the force-deflection characteristics of the thorax of children and young adults during CPR. To do so, a force and deflection sensor was integrated into a patient monitor-defibrillator used during CPR in the Pediatric Intensive Care Unit and Emergency Department of a children's hospital. The sensor was interposed between the chest of the patient and hands of the rescuer during CPR compressions. Following a CPR event, thoracic force and deflection data were downloaded from the monitor-defibrillator for analysis. Each compression cycle was fit to a parallel spring-damper model, wherein stiffness and damping were linearly dependent on chest deflection. Average maximum chest deflection, force at maximum deflection, linear stiffness, and elastic and viscous model forces are reported for each subject and correlated with age. Eighteen subjects (11 females) ages 8 to 22 years were enrolled in the study and each received a mean of 2000 (Standard Deviation 2339) chest compressions during CPR. Average maximum chest deflection and corresponding force were 39 +/- 5 mm and 309 +/- 55 N respectively. When combined with our previous study of adult CPR data, and other data from the literature, our findings suggest that the stiffness of the thorax increases from youth to middle age, and then decreases in the elderly. CPR has the potential to provide data from a wide range of human subjects with which to study the effect of age on mechanics of thoracic deformation. Future studies will expand the sample size and age range of data collected to further explore the age-related changes in thoracic mechanics.
Available from: Katarina Bohman
- "The cartilage is most elastic in youth and becomes stiffer as the cartilage calcifies with age. Together, these factors results in a structural stiffness that gradually increases from youth to middle age  "
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ABSTRACT: The protection of children in motor vehicle crashes has improved since the introduction of child restraint systems. However, motor vehicle crashes remain one of the top leading causes of death for children. Today, computer-aided engineering is an essential part of vehicle development and it is anticipated that safety assessments will increasingly rely on simulations. Therefore, this study presents a review of important biomechanical aspects for the safety of children in cars, including child human body models, for scenarios ranging from on-road driving, emergency maneuvers, and pre-crash events to crash loading. The review is divided into four parts: Crash safety, On-road driving for forward facing children, Numerical whole body models, and Discussion and future outlook.
Available from: Yun-Seok Kang
- "Similar trends have been found in other experimental test series in which a broad age range is included in the sample. Maltese and colleagues  report the stiffness of child thoraces based on cardiopulmonary resuscitation techniques. They present a compilation of data from their study, from  and , that depicts an age-associated trend in thorax stiffness in which an increase in peak force is observed until the end of the young adult period, at which point the force declines. "
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ABSTRACT: The risk of rib fracture significantly increases with age with compounding deleterious effects. Previous research identifying rib properties has provided useful information for application in car safety. However, no study to-date has included a comprehensive sample including pediatric and elderly ribs tested in the same repeatable set-up. The goal of this study is to characterize the differences in rib response across the age spectrum. Seventy-one excised ribs from 26 individuals were experimentally tested in a custom fixture simulating a dynamic frontal impact. Four strain gages on each rib were used to determine time of failure. Ages ranged from nine to 92 years old, with a mean age of 61 years and with the exception of the 50's, all age decades are represented. Effective stiffness (K) was calculated as the slope of the linear portion of the force-deflection curve. Rib pairs were tested at different rates (1.0 and 2.0 m/s) to assess the rate-dependency of stiffness. Results indicate a significant difference in effective stiffness by age (evaluated by ANOVA, p < 0.001) and no difference by rate within rib pairs (evaluated by paired t-test, p = 0.125).
Available from: Binhui Jiang
- "Conclusion An anatomically detailed, high-resolution 10-year-old FE thorax model was developed and validated against data obtained from the real-world CPR. The CPR experiment was performed at a relatively low speed, with a maximum loading rate of 250 mm/s (Maltese et al. 2008). Although tissue material properties were scaled from adults, the 10-year-old FE model was validated during a loading event for which inertial effects were minimal. "
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ABSTRACT: Thoracic injury in the paediatric population is a relatively common cause of severe injury and has an accompanying high mortality rate. However, no anatomically accurate, complex paediatric chest finite element (FE) component model is available for a 10-year old in the published literature. In this study, a 10-year-old thorax FE model was developed based on internal and external geometries segmented from medical images. The model was then validated against published data measured during cardiopulmonary resuscitation performed on paediatric subjects.
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