Assessment of the Smartpill, a Wireless Sensor, as a Measurement Tool for Intra-Abdominal Pressure (IAP).

Background: The SmartPill, a multisensor ingestible capsule, is marketed for intestinal motility disorders. It includes a pressure sensor, which could be used to study intra-abdominal pressure (IAP) variations. However, the validation data are lacking for this use. Material and Methods: An experimental study was conducted on anesthetized pigs with stepwise variations of IAP (from 0 to 15 mmHg by 3 mmHg steps) generated by laparoscopic insufflation. A SmartPill, inserted by endoscopy, provided intragastric pressure data. These data were compensated to take into account the intrabdominal temperature. They were compared to the pressure recorded by intragastric (IG) and intraperitoneal (IP) wired sensors by statistical Spearman and Bland-Altmann analysis. Results: More than 4500 pressure values for each sensor were generated on two animals. The IG pressure values obtained with the SmartPill were correlated with the IG pressure values obtained with the wired sensor (respectively, Spearman ρ coefficients 0.90 ± 0.08 and 0.72 ± 0.25; bias of -28 ± -0.3 mmHg and -29.2 ± 0.5 mmHg for pigs 1 and 2). The intragastric SmartPill values were also correlated with the IAP measured intra-peritoneally (respectively, Spearman ρ coefficients 0.49 ± 0.18 and 0.57 ± 0.30; bias of -29 ± 1 mmHg and -31 ± 0.7 mmHg for pigs 1 and 2). Conclusions: The SmartPill is a wireless and painless sensor that appears to correctly monitor IAP variations.

Semiautomatic quantification of abdominal wall muscles deformations based on dynamic MRI image registration.

Quantitative analysis of abdominal organs motion and deformation is crucial to better understand biomechanical alterations undermining respiratory, digestive or perineal pathophysiology. In particular, biomechanical characterization of the antero-lateral abdominal wall is central in the diagnosis of abdominal muscle deficiency. Here, we present a dedicated semiautomatic dynamic MRI postprocessing method enabling the quantification of spatial and temporal deformations of the antero-lateral abdominal wall muscles. Ten healthy participants were imaged during a controlled breathing session at the L3-L4 disc level using real-time dynamic MRI at 3 T. A coarse feature-tracking step allowed the selection of the inhalation cycle of maximum abdominal excursion. Over this image series, the described method combines (1) a supervised 2D+t segmentation procedure of the abdominal wall muscles, (2) the quantification of muscle deformations based on masks registration, and (3) the mapping of deformations within muscle subzones leveraging a dedicated automatic parcellation. The supervised 2D+t segmentation (1) provided an accurate segmentation of the abdominal wall muscles throughout maximum inhalation with a 0.95 ± 0.03 Dice similarity coefficient (DSC) value and a 2.3 ± 0.7 mm Hausdorff distance value while requiring only manual segmentation of 20% of the data. The robustness of the deformation quantification (2) was indicated by high indices of correspondence between the registered source mask and the target mask (0.98 ± 0.01 DSC value and 2.1 ± 1.5 mm Hausdorff distance value). Parcellation (3) enabled the distinction of muscle substructures that are anatomically relevant but could not be distinguished based on image contrast. The present genuine postprocessing method provides a quantitative analytical frame that could be used in further studies for a better understanding of abdominal wall deformations in physiological and pathological situations.

Assessing HIV provider knowledge, screening practices, and training needs for HIV-associated neurocognitive disorders. A short report.

Management of HIV-associated neurocognitive disorders (HAND) is becoming increasingly important with HIV-positive people living normal life spans. We aimed to establish the level of HAND awareness among doctor and nurse occupational health practitioners, screening used to detect impairment, factors limiting screening for HAND, and training needs. One-hundred-and-five members of the nursing and physician professional societies for occupational health practitioners in South Africa and Occupational Health Departments at five South African universities responded to an email invitation to complete an online survey addressing demographics, HAND knowledge, screeners being used to screen for HAND and related training needs. While 80% had heard of HAND, few (13.3%) were aware of the Frascati criteria. Only 2% had received training addressing HAND; 11.4% screened for HAND; 45.7% did not know what screening tool to us; 80% preferred spending <15 min on screening. The largest obstacle to screening was lack of expertise (77.1%) but 77.3% thought it important to screen for HAND. 94.3% wanted screening training. Health providers are poorly informed about HAND and lack expertise and tools to screen for HAND in their treatment programs. While few had relevant training, they recognize the importance of screening for HAND in the workplace and desire training.

Testosterone administration in women increases the size of their peripersonal space.

Peripersonal space (PPS) is the space immediately surrounding the body, conceptualised as a sensory-motor interface between body and environment. PPS size differs between individuals and contexts, with intrapersonal traits and states, as well as social factors having a determining role on the size of PPS. Testosterone plays an important role in regulating social-motivational behaviour and is known to enhance dominance motivation in an implicit and unconscious manner. We investigated whether the dominance-enhancing effects of testosterone reflect as changes in the representation of PPS in a within-subjects testosterone administration study in women (N = 19). Participants performed a visuo-tactile integration task in a mixed-reality setup. Results indicated that the administration of testosterone caused a significant enlargement of participants' PPS, suggesting that testosterone caused participants to implicitly appropriate a larger space as their own. These findings suggest that the dominance-enhancing effects of testosterone reflect at the level of sensory-motor processing in PPS.

Abdominal wall morphometric variability based on computed tomography: Influence of age, gender, and body mass index.

INTRODUCTION: Ventral hernia surgery does not usually account for the individuality of the abdominal wall anatomy. This could be both because medical imaging is rarely performed before surgery and because data on abdominal wall variability are limited. The objective of the present study was to perform an exhaustive morphometric analysis of abdominal wall components based on computed tomography (CT) scans. MATERIALS AND METHODS: A retrospective study was performed on 120 abdominopelvic CT scans of clinically normal adults aged 18-86 years equally divided between women and men and into four age groups. Each abdominal wall muscle was evaluated in terms of area, thickness, shape ratio, fat infiltration, and aponeuroses width. The influence of age, gender, and body mass index (BMI) was investigated, as well as muscular asymmetry. RESULTS: The abdominal wall muscle area represented 8.5 ± 2.5% of the abdominal area. The internal oblique muscle had the largest area, the rectus abdominis was the thickest, the transversus abdominis was the narrowest and had the smallest area. The width of the linea alba was 20.3 ± 12.0 mm. The evolution of the abdominal wall with age was quantified, as well as the large differences between the sexes and BMI groups, resulting in strong correlations and highlighting the specific pattern of the transversus abdominis. The asymmetry of the left and right muscle areas oscillated around 17%. CONCLUSIONS: The various components of the abdominal wall have been precisely described. Knowledge of their variability could be used to enhance the planning of ventral hernia surgery or to develop numerical modeling of the abdominal wall.

Effect of Helmet Use on Traumatic Brain Injuries and Other Head Injuries in Alpine Sport.

INTRODUCTION: Sport helmet effectiveness in preventing traumatic brain injury (TBI) has been repeatedly questioned. This study assesses the effect of helmet use on risk of TBI and other types of head injury (OTHI) in alpine sports. METHODS: From 2012 to 2014, data on the injured population were collected by physicians in on-mountain clinics in 30 French ski resorts, and interviews were conducted on the slope to sample a noninjured control population. Two sets of cases (1425 participants with TBI and 1386 with OTHI) were compared with 2 sets of controls (2145 participants without injury and 40,288 with an injury to a body part other than the head). The effect of helmet use on the risk of TBI and OTHI was evaluated with a multivariate logistic regression adjusted for age, sex, sport, skill level, crash type, and crash location. RESULTS: Using participants without injury as control, we found that helmet wearers were less likely to sustain any head injury (odds ratio [OR]TBI = 0.65; OROTHI = 0.42). When considering participants with an injury to another body part as control, the risk of OTHI was lower among helmet wearers (OROTHI: 0.61). However, no significant effect was found for the risk of TBI. Participants with low skill levels, those aged <26 and >50 years, snowboarders, and those involved in collision and in snowpark accidents were at higher risk of head injury. CONCLUSIONS: This study confirms the effectiveness of helmets in protecting users from head injuries but questions their effects on TBI, especially concussion.

Temporal bone fractures: sequelae and their impact on quality of life.

PURPOSE: To present a prospective temporal bone fracture database, and study facial and cochleovestibular sequelae and their impact on quality of life. MATERIALS AND METHODS: Prospective study of consecutive cases of 39 patients with 45 temporal bone fractures over 11-month period in a university tertiary referral center. Based on epidemiological data, clinical and imaging findings, treatment modalities and outcome of patients with follow-up of one year, the present study focused on facial and cochleovestibular sequelae and their impact on quality of life after one-year period. RESULTS: After 12 months, 44% of patients present with balance problems, 56% with hypoacusis, 56% with tinnitus, and 15% with facial paralysis. In 75%-80% of patients, the cochleovestibular sequelae are described as disabling. Post-trauma quality of life was significantly impaired compared with pre-trauma quality of life, even after 12 months. Long-term cochleovestibular sequelae were significantly associated with poor long-term quality of life. CONCLUSIONS: The study demonstrates the need to focus on prevention of temporal bone fractures, notably by promoting the use of helmets and improvements in helmet design. The rapid diagnosis of temporal bone fracture is crucial as it enables effective initial management aimed at avoiding sequelae. The frequency of cochleovestibular sequelae after temporal bone fracture and their impact on quality of life demonstrate the importance of, and need for, ongoing follow-up by a local medical team who can diagnose and manage these long-term sequelae.

Three-dimensional variability of the mesentery and the superior mesenteric artery: application to virtual trauma modeling.

INTRODUCTION: Trauma is a major cause of death worldwide, mainly affecting a young male population. Blunt trauma of the abdomen can cause a trauma of the mesentery in 5 % of cases. Rapid decelerations and injuries by seat belts are the most common pathophysiological mechanisms. Three-dimensional anatomical scanning of the mesentery and gastrointestinal tract is the first essential step in modeling abdominal trauma in an attempt to understand the pathophysiology of mesenteric lesions and to improve the safety features of vehicles. OBJECTIVE OF THE STUDY: To analyze the individual variability of the mesentery and the superior mesenteric artery (SMA) from medical imaging and to develop a three-dimensional customizable finite element model. MATERIALS AND METHODS: In this retrospective study, one hundred abdominopelvic injected CT scans were analyzed from healthy patients. The evaluation criteria of the mesentery were its volume (total and the distribution of adipose tissue/non adipose tissue), the length of the SMA and the distance between duodenojejunal angle (DJA) and the ileocecal junction (ICJ). The variability of these measures has been studied by demographic (age and gender) and morphologic (height evaluated by the T11-L4 distance, the waist circumference and the thickness of the subcutaneous adipose tissue). RESULTS: Mean mesenteric volume was 644 cm(3) (ranges from 89 to 1,869 cm(3)), and the mean length of the SMA was 224.9 mm (ranges from 138.4 to 312.3). There was a statistically significant association between waist circumference and the total volume of the mesentery, its fat component and non fat component (p < 0.001). Waist circumference was the only morphological parameter associated with the length of the superior mesenteric artery and the length of the DJA to ICJ (p < 0.001). Subcutaneous adipose tissue and female sex were statistically associated with total mesentery volume (respectively, p = 0.005 and p = 0.001). Age was an independent predictor of the increased volume of the mesentery and the length of the SMA. The height of the subject changes the length of the SMA (p = 0.001). CONCLUSION: The assessment of the mesenteric variability highlighted three factors associated with its size and length: age, sex, and waist circumference. These parameters have to be taken into account to personalize numerical model in the area of virtual trauma.

Crew and patient safety in ambulances: results of a personnel survey and experimental side impact crash test.

INTRODUCTION: Ambulance drivers often travel under stressful conditions at high speed while using vehicles with poor high-speed maneuverability. The occupant safety of ambulance vehicles has not yet been addressed by the automotive safety paradigm; particularly for the rear patient compartment. This study had two objectives: (1) to assess by survey the French Emergency Medical Services (EMS) to determine the layout of the vehicle most often used and the EMS personnel's behavior during transport; and (2) to conduct a crash test to analyze the injuries which may affect EMS personnel and patients in the rear patient compartment. METHOD: Firstly, a survey was distributed to the 50 largest metropolitan French EMS programs. Secondly, a crash test was performed with a Mobile Intensive Care Unit (MICU) in conditions closest to reality. RESULTS: Forty-nine of the 50 biggest metropolitan French EMS programs responded to the survey. This represents 108 French MICUs. During the last three years, 12 of 49 EMS programs (24%) identified at least one accident with an MICU, and six of these 12 (50%) suffered at least one death in those accidents. A crash test using a typical French EMS MICU showed that after impact of a collision, the ambulance was moved more than five meters with major consequences for all passengers. A study-approved human cadaver placed in the position of a potential patient was partially thrown from the stretcher with a head impact. The accelerometric reaction of the anthropomorphic manikin head was measured at 48G. CONCLUSION: The crash test demonstrated a lack of safety for EMS personnel and patients in the rear compartment. It would be preferable if each piece of medical equipment were provided with a quick release system resistant to three-dimensional 10G forces. The kinetic changes undergone by the "patient" substitute on the stretcher would probably have an effect of causing injury pathology. This study highlights the need for more research and development in this area.

Three-dimensional determination of variability in colon anatomy: applications for numerical modeling of the intestine.

BACKGROUND: Precise knowledge of variability in colonic anatomy is of great importance for numerical modeling studies of the abdomen. This knowledge would allow the creation of personalized models for the gastrointestinal tract used for surgical simulations or in studies of virtual trauma. MATERIALS AND METHODS: To determine the colonic configuration in the general population and define its variability by gender, age, and corpulence, the layout of the colon was determined via the following reference points: ileocecal junction, left and right colonic flexures, and colosigmoid junction (CSJ). Three-dimensional coordinates for each point were recorded on scanned sections of 100 healthy adults to examine the colonic layout under physiological conditions. Coordinates were repositioned in a new anatomical reference for comparison. The average points' coordinates, standard deviations, and distances between them were compared for each group. RESULTS: The right colonic flexure was the most variable point. The CSJ was the least variable. Gender affected mainly the height of the colonic flexures and the length of its segments. Age affected the length of the transverse mesocolon root. Corpulence affected both the position of the ileocecal and CSJs and the length of the right colon. Differences in size and perivisceral fat distribution between groups explained these differences. Three-dimensional anatomical models of the colon were defined for each group by statistical equations. CONCLUSION: These equations, combined with data concerning the actual lengths of the colonic segments, enable reconstruction of different anatomical models of the colon that are representative according to gender, age, and corpulence.

A better understanding of daily life abdominal wall mechanical solicitation: Investigation of intra-abdominal pressure variations by intragastric wireless sensor in humans.

Intra-abdominal pressure (IAP), as the main mechanical load applied to the abdominal wall, is decisive in the occurrence of ventral hernia. The objective of the study was to propose a comprehensive evaluation of IAP based on a limited risk and discomfort method. A prospective study was carried out in 20 healthy volunteers. The intragastric pressure, validated for estimating IAP, was assessed by an ingestible pressure sensor. Volunteers realized a set of supervised exercises, then resumed their daily activities with the pressure continuously recorded until gastric emptying. Coughing and jumping exercises resulted in the highest IAP levels with maximum peaks of 65 ± 35 and 67 ± 31 mmHg and pressure rates of 121 and 114 mmHg.s-1 respectively. The position did not affect the IAP variation. Men had significantly higher pressure values for pushing against a wall (P < 0.01), Valsalva maneuver and legs raising (P<0.05) exercises. During daily life, IAP greater than 50, 100, and 150 mmHg occurred on average five times, twice, and once per hour, respectively. This study provides a real-life characterization of the IAP allowing the quantification of mechanical solicitation applied to the abdominal wall and the identification of risk situations for the occurrence of ventral hernias.

Analysis of the Acoustic Transcranial Bone Conduction.

OBJECTIVES: (1) To analyze the preferential pathways of sound transmission and sound waves travelling properties in the skull and (2) to identify the location(s) on the skull where bone conduction to the cochlea is optimal. STUDY DESIGN: Basic research Methods: Nine cadaveric heads were placed in an anechoic chamber and equipped with six Bone Anchored Hearing Aids (BAHA™) implants (Cochlear™, Sydney, NSW, Australia) and fifteen accelerometers. A laser velocimeter was used to measure cochlear response by placing a reflector on the round window. Different frequency sweeps were applied to each implant, and measurements were recorded simultaneously by the laser velocimeter and accelerometers. RESULTS: Low-frequency sound waves mostly travel the frontal transmission pathways, and there is no clear predominant pattern for the high frequencies. The mean inter-aural time lag is 0.1 ms. Optimal sound transmission to the cochlea occurs between 1000 and 2500 Hz with a contralateral 5 to 10 dB attenuation. The implant location does not influence mean transmission to the cochlea. CONCLUSION: There is a pattern of transmission for low frequencies through a frontal pathway but none for high frequencies. We were also able to demonstrate that the localization of the BAHA™ implant on the skull had no significant impact on the sound transmission, either ipsi or contralaterally.

Dynamic-MRI quantification of abdominal wall motion and deformation during breathing and muscular contraction.

BACKGROUND AND OBJECTIVE: Biomechanical assessment of the abdominal wall represents a major prerequisite for a better understanding of physiological and pathological situations such as hernia, post-delivery recovery, muscle dystrophy or sarcopenia. Such an assessment is challenging and requires muscular deformations quantification which have been very scarcely reported in vivo. In the present study, we intended to characterize abdominal wall deformations in passive and active conditions using dynamic MRI combined to a semiautomatic segmentation procedure. METHODS: Dynamic deformations resulting from three complementary exercises i.e. forced breathing, coughing and Valsalva maneuver were mapped in a transversal abdominal plane and so for twenty healthy volunteers. Real-time dynamic MRI series were acquired at a rate of 182 ms per image, then segmented semi-automatically to follow muscles deformation through each exercise. Circumferential and radial strains of each abdominal muscle were computed from the geometrical characteristics' quantification, namely the medial axis length and the thickness. Muscular radial displacement maps were computed using image registration. RESULTS: Large variations in circumferential and radial strains were observed for the lateral muscles (LM) but remained low for the rectus abdominis muscles (RA). Contraction phases of each exercise led to LM muscle shortening down to -9.6 ± 5.9% during Valsalva maneuver with a 16.2 ± 9.6% thickness increase. Contraction also led to inward radial displacement of the LM up to 9.9 ± 4.1 mm during coughing. During maximal inhalation, a significant 10.0 ± 6.6% lengthening was quantified for LM while a significant thickness decrease was computed for the whole set of muscles (-14.7 ± 6.6% for LM and -7.3 ± 6.5% for RA). The largest displacement was observed for the medial part of RA (17.9 ± 8.0 mm) whereas the posterior part of LM underwent limited motion (2.8 ± 2.3 mm). Displacement rate and correlation between muscle thickness and medial axis length during each exercise provided insights regarding subject-specific muscle function. CONCLUSIONS: Dynamic MRI is a promising tool for the assessment of the abdominal wall motion and deformations. The corresponding metrics which have been continuously recorded during the exercises provided global and regional quantitative information. These metrics offer perspectives for a genuine clinical evaluation tool dedicated to the assessment of abdominal muscles function in both healthy subjects and patients.

Impact of HIV on Cognitive Performance in Professional Drivers.

BACKGROUND: The intellectually demanding modern workplace is often dependent on good cognitive health, yet there is little understanding of how neurocognitive dysfunction related to HIV presents in employed individuals working in high-risk vocations such as driving. HIV-associated neurocognitive impairment is also associated with poorer long-term cognitive, health, and employment outcomes. SETTING: This study, set in Cape Town, South Africa, assessed the effects of HIV on neuropsychological test performance in employed male professional drivers. METHOD: We administered a neuropsychological test battery spanning 7 cognitive domains and obtained behavioral data, anthropometry, and medical biomarkers from 3 groups of professional drivers (68 men with HIV, 55 men with cardiovascular risk factors, and 81 controls). We compared the drivers' cognitive profiles and used multiple regression modeling to investigate whether between-group differences persisted after considering potentially confounding sociodemographic and clinical variables (ie, income, home language, depression, and the Framingham risk score). RESULTS: Relative to other study participants, professional drivers with HIV performed significantly more poorly on tests assessing processing speed (P < 0.003) and attention and working memory (P = 0.018). Group membership remained a predictor of cognitive performance after controlling for potential confounders. The cognitive deficits observed in men with HIV were, however, largely characterized as being mild or asymptomatic. Consistent with this characterization, their relatively poor performance on neuropsychological testing did not generalize to self-reported impairment on activities of daily living. CONCLUSION: Drivers with HIV may be at risk of poorer long-term health and employment outcomes. Programs that monitor and support their long-term cognitive health are needed.

About some factors influencing safety mattress performances in head impact collisions: A pilot study.

OBJECTIVES: In recreational snow sports activities, safety mattresses are placed on obstacles to prevent injuries from a collision with users. However, the performances of these devices in field conditions remain unclear. The objective of this study is to evaluate the effect of mattress thickness, impact speed, impacting mass and atmospheric conditions on head acceleration during an in-field impact on safety mattress. DESIGN: 42 in-field experimental drop tests of a normative metallic head were conducted on safety mattress to assess the influence of impact speed (5.8m/s or 7.3m/s), impacting mass (6kg or 11.6kg), outside conditions (3 conditions) and mattress thickness (24cm, 32cm, 44cm) on head acceleration at impact. METHODS: Linear accelerations were measured and Head Injury Criteria 15ms (HIC15) was computed. A statistical analysis (ANOVA) was used to characterize the effects of the varying parameters on maximal acceleration and HIC15. RESULTS: Reduced impact speed, increased mattress thickness and change in the outside conditions significantly decreased the head acceleration and HIC15 (p<0.001). The effect of the impacting mass on head acceleration was not significant. CONCLUSIONS: This study highlights the influence of impact speed, atmospheric condition and mattress construction on absorption capacities of safety mattresses. It is a first step toward a better understanding and evaluation of safety mattresses performances.

The predictive capacity of the MADYMO ellipsoid pedestrian model for pedestrian ground contact kinematics and injury evaluation.

Pedestrian injuries occur in both the primary vehicle contact and the subsequent ground contact. Currently, no ground contact countermeasures have been implemented and no pedestrian model has been validated for ground contact, though this is needed for developing future ground contact injury countermeasures. In this paper, we assess the predictive capacity of the MADYMO ellipsoid pedestrian model in reconstructing six recent pedestrian cadaver ground contact experiments. Whole-body kinematics as well as vehicle and ground contact related aHIC (approximate HIC) and BrIC scores were evaluated. Reasonable results were generally achieved for the timings of the principal collision events, and for the overall ground contact mechanisms. However, the resulting head injury predictions based on the ground contact HIC and BrIC scores showed limited capacity of the model to replicate individual experiments. Sensitivity studies showed substantial influences of the vehicle-pedestrian contact characteristic and certain initial pedestrian joint angles on the subsequent ground contact kinematics and injury predictions. Further work is needed to improve the predictive capacity of the MADYMO pedestrian model for ground contact injury predictions.

An Experimental Study of Intraluminal Hyperpressure Reproducing a Gastric Leak Following a Sleeve Gastrectomy.

INTRODUCTION: A gastric leak (GL) represents the main post-operative complication following a sleeve gastrectomy (SG) and occurs most commonly at the top of the stapling, without any clear explanation. OBJECTIVE: This experimental study evaluates the biomechanical behavior of post-SG gastric specimens using both insufflation and tensile tests. MATERIALS AND METHODS: A total gastrectomy followed by an ex vivo SG was performed in 15 pigs. The "sleeved" stomachs were subjected to intraluminal hyperpressure until failure. Uniaxial circumferential and longitudinal tensile tests were performed using gastric strips obtained from the "resected" stomachs. All the deformations and burst pressures were recorded and analyzed. RESULTS: A GL appeared in the upper third of the stapling in 73% of cases. The mean burst pressure was 26.3 ± 5.3 mmHg and was significantly correlated with the volume of the "sleeved" stomachs (p = 0.02). The overall deformation of the "sleeved" stomachs was comparable in the frontal (38.3%) and profile (40.5%) planes. The greatest displacement was observed at the failure zone (11 mm on average). The biomechanical behavior of the stomach wall differed according to the strip orientation. The circumferential strips presented a higher strain-to-failure rate (97%) and a lower Young's modulus (0.99 MPa) when compared to the longitudinal strips (45% and 2.58 MPa, respectively). CONCLUSION: This preliminary study reproduced a GL in the same location as observed during clinical practice. The volume of the SG influenced the burst pressure. Further experimental studies and numerical simulations should evaluate the impact of shape modifications on an SG.

Analysis of trunk impact conditions in motorcycle road accidents based on epidemiological, accidentological data and multibody simulations.

Motorcycle accidents lead to a high rate of traffic mortality and morbidity. While helmet development and mandatory wearing have reduced head injuries, little progress has been made regarding trunk protection. Wearable airbag devices represent a promising solution to prevent trunk injuries. Nevertheless, research investigations need to be performed to assess and optimise the efficiency of such devices. This work consisted in the analysis of motorcyclist trunk impact conditions involved in various crash configurations to provide critical information in order to evaluate and improve the performances of airbag devices. First, an epidemiological and an accidentological analysis of data collection related to 252 real accidents, focusing on victims admitted into the shock rooms of two French trauma centres were performed. The data obtained was combined with numerical multibody parametric investigations, allowing the reproduction of 240 accident situations. An original and representative analysis of motorcyclists' impact conditions was provided, weighting the numerical study output data according to the real accident database. The impacted regions of the human body, the impact velocity and the accident chronology obtained in this work made it possible to define critical information for airbag efficiency assessment: the zones and levels of protection, the impacted surfaces as well as the airbag intervention time and the duration of maintained inflation of the airbag.

A novel method to quantitate bioprosthetic valve leaflet mechanical stress: a numerical and in vitro study.

An original in vitro/in silico method was developed to estimate the local and global mechanical stress applied on the bioprosthetic valve leaflet, which can be important for better understanding of the valve durability. A non-contact system based on stereophotogammetry and digital image correlation enabled filming and studying the valve leaflet movement frame by frame and performing three-dimensional analysis. The deformation was applied in a finite element model in order to calculate the local mechanical stress applied. High stress regions were primarily observed in the upper leaflet edge and belly and to a lesser extent at the free leaflet edge.

Numerical Reconstruction of Traumatic Brain Injury in Skiing and Snowboarding.

PURPOSE: Proper evaluation of ski helmet designs and safety standards should rely on head impact conditions involved in skiing and snowboarding head injuries. To study these impacts, main crash scenarios involving head injuries are numerically replicated. METHODS: Multibody models of skiers and snowboarders were developed to investigate five common crash scenarios involved in traumatic brain injury: forward and sideways skiing falls, snowboarding backward falls, collisions between users and collisions with obstacles. For each scenario, the influence of crash conditions on head impact (location, speed, linear and rotational accelerations) and risk of injury are evaluated. Crash conditions were initial velocity, user height, position and approach angle, slope steepness, obstacles, and snow stiffness. RESULTS: One thousand one hundred forty-nine crashes were simulated and three significant levels of impact conditions were discriminated over the investigated crash scenarios: 1) the smallest normal-to-slope impact velocities (6 km·h; 22 km·h) and peak linear accelerations (42g; 75g) were obtained during forward and sideways skiing falls; 2) snowboarding backward falls and collisions between users were associated with high normal-to-surface impact velocities (26 km·h; 32 km·h) and head accelerations (80g; 149g) above one published threshold for mild traumatic brain injury but below the pass/fail criteria of helmet standard tests; 3) collisions with obstacles were associated with high normal-to-surface impact velocities (19 km·h; 35 km·h) and the highest head accelerations (626g; 1885g). CONCLUSIONS: Current impact conditions of helmet standard evaluations consistently replicate collisions with obstacles, but need to be revised to better reflect other significant crash scenarios leading to traumatic brain injury.