Although there have been tremendous improvements in crash safety there has been an increasing trend in side impact fatalities, rising from 30% to 37% of total fatalities from 1975 to 2004 (NHTSA, 2004). Between 1979 and 2004, 63% of AIS≥4 injuries in side impact resulted from thoracic trauma (NHTSA, 2004). Lateral impact fatalities, although decreasing in absolute numbers, now comprise a larger percentage of total fatalities. Safety features are typically more effective in frontal collisions compared to side impact due to the reduced distance between the occupant and intruding vehicle in side impact collisions. Therefore, an increased understanding of the mechanisms governing side impact injury is necessary in order to improve occupant safety in side impact auto crash. This study builds on an advanced numerical human body model with focus on a detailed thoracic model, which has been validated using available post mortem human subject (PMHS) test data for pendulum and side sled impact tests (Forbes, 2005). Crash conditions were investigated through use of a modified side sled model used to reproduce the key conditions present in full scale crash tests. The model accounts for several important factors that contribute to occupant response based on the literature. These factors are; the relative velocities between the seat and door, the occupant to door distance, the door shape and compliance. The side sled model was validated by reproducing the crash conditions present in FMVSS 214 and IIHS side impact tests and comparing the thoracic compression, velocity, and Viscous Criterion (VC) response determined by the model to the response of the ES-2 dummy used in the crash tests. Injury was predicted by evaluating VCmax, selected for its ability to predict rate-sensitive soft tissue injury during thoracic compression (Lau & Viano, 1986). The Ford Taurus FMVSS 214 and Nissan Maxima IIHS tests were selected from side impact crash test data found in the NHTSA database because they included factors not present in standard side impact test procedures. These factors were; the presence of door accelerometers used to provide input velocities to the side impact model and the use of a ES-2 (rather than the SID) to facilitate comparison of VC response to the human body model. Also, the two crash test procedures (FMVSS 214 & IIHS) were selected to ensure accurate side impact model response to different impact scenarios. The side impact model was shown to closely reproduce the timing and injury response of the full-scale FMVSS 214 side impact test of a Ford Taurus, as well as the IIHS side impact test of a Nissan Maxima. The side impact model was then used to investigate the effects of door to occupant spacing, door velocity profile, armrest height, seat foam, restraint system, and arm position. It was found that the VCmax was controlled by both the first and second peaks typically found in door velocity profiles, but the effect of each varies depending on the situation. This study found that VCmax was reduced by 73-88% when door intrusion was eliminated compared to the VC response incurred by an intruding door. Also, the presence of a deformable door based on physical geometry and material characteristics rather than a simplified rigid door reduced VCmax by 16% in this study. The study on seat foam determined that significant effects on VC response can be made by modest adjustments in foam properties. Low stiffness seat foam was found to increase VCmax by 41% when compared to the VC response when using high stiffness foam. Arm position has been proven to be a relevant factor in side impact crash. Positioning the arms parallel to the thorax, in the “down” position, caused a 42% increase in VCmax when compared to the VC response determined with the arms positioned at 45 degrees. Finally, although restraint systems have limited influence on side impact crash safety compared to front and rear impacts, this study found that the presence of a pre-tensioning restraint system reduced VCmax by 13% when compared to the VC response of an un-belted occupant. It should be noted that the current study was limited to velocity profiles obtained from a specific FMVSS 214 test and therefore results and observations are restricted to the confines of the input conditions used. However, the side impact model developed is a useful tool for evaluating factors influencing side impact and can be used to determine occupant response in any side impact crash scenario when the appropriate input conditions are provided.

Although there have been tremendous improvements in crash safety there has been an increasing trend in side impact fatalities, rising from 30% to 37% of total fatalities from 1975 to 2004 (NHTSA, 2004). Between 1979 and 2004, 63% of AIS≥4 injuries in side impact resulted from thoracic trauma (NHTSA, 2004). Lateral impact fatalities, although decreasing in absolute numbers, now comprise a larger percentage of total fatalities. Safety features are typically more effective in frontal collisions compared to side impact due to the reduced distance between the occupant and intruding vehicle in side impact collisions. Therefore, an increased understanding of the mechanisms governing side impact injury is necessary in order to improve occupant safety in side impact auto crash. This study builds on an advanced numerical human body model with focus on a detailed thoracic model, which has been validated using available post mortem human subject (PMHS) test data for pendulum and side sled impact tests (Forbes, 2005). Crash conditions were investigated through use of a modified side sled model used to reproduce the key conditions present in full scale crash tests. The model accounts for several important factors that contribute to occupant response based on the literature. These factors are; the relative velocities between the seat and door, the occupant to door distance, the door shape and compliance. The side sled model was validated by reproducing the crash conditions present in FMVSS 214 and IIHS side impact tests and comparing the thoracic compression, velocity, and Viscous Criterion (VC) response determined by the model to the response of the ES-2 dummy used in the crash tests. Injury was predicted by evaluating VCmax, selected for its ability to predict rate-sensitive soft tissue injury during thoracic compression (Lau & Viano, 1986). The Ford Taurus FMVSS 214 and Nissan Maxima IIHS tests were selected from side impact crash test data found in the NHTSA database because they included factors not present in standard side impact test procedures. These factors were; the presence of door accelerometers used to provide input velocities to the side impact model and the use of a ES-2 (rather than the SID) to facilitate comparison of VC response to the human body model. Also, the two crash test procedures (FMVSS 214 & IIHS) were selected to ensure accurate side impact model response to different impact scenarios. The side impact model was shown to closely reproduce the timing and injury response of the full-scale FMVSS 214 side impact test of a Ford Taurus, as well as the IIHS side impact test of a Nissan Maxima. The side impact model was then used to investigate the effects of door to occupant spacing, door velocity profile, armrest height, seat foam, restraint system, and arm position. It was found that the VCmax was controlled by both the first and second peaks typically found in door velocity profiles, but the effect of each varies depending on the situation. This study found that VCmax was reduced by 73-88% when door intrusion was eliminated compared to the VC response incurred by an intruding door. Also, the presence of a deformable door based on physical geometry and material characteristics rather than a simplified rigid door reduced VCmax by 16% in this study. The study on seat foam determined that significant effects on VC response can be made by modest adjustments in foam properties. Low stiffness seat foam was found to increase VCmax by 41% when compared to the VC response when using high stiffness foam. Arm position has been proven to be a relevant factor in side impact crash. Positioning the arms parallel to the thorax, in the “down” position, caused a 42% increase in VCmax when compared to the VC response determined with the arms positioned at 45 degrees. Finally, although restraint systems have limited influence on side impact crash safety compared to front and rear impacts, this study found that the presence of a pre-tensioning restraint system reduced VCmax by 13% when compared to the VC response of an un-belted occupant. It should be noted that the current study was limited to velocity profiles obtained from a specific FMVSS 214 test and therefore results and observations are restricted to the confines of the input conditions used. However, the side impact model developed is a useful tool for evaluating factors influencing side impact and can be used to determine occupant response in any side impact crash scenario when the appropriate input conditions are provided.

Les impacts non transfixiants sur les gilets pare-balles sont responsables de lésions non pénétrantes potentiellement létales, regroupées sous le terme d’effets arrière (Behind Armor Blunt Trauma : BABT). De telles lésions fermées se retrouvent également lors d’impacts thoraciques de projectiles d’Armes à Létalité Réduite cinétiques (ALRc). Afin d’améliorer le pouvoir protecteur des protections balistiques et de mieux maitriser le pouvoir vulnérant des ALRc, il est nécessaire de définir un critère lésionnel permettant de prédire l’importance des lésions en cas de traumatisme thoracique fermé de type balistique. Ce critère se doit d’être bien corrélé à la gravité du traumatisme, et de pouvoir être facilement transposable à l’ensemble des systèmes d’évaluation des protections balistiques et des ALRc. La gravité du traumatisme a été définie ici par le volume de la contusion pulmonaire. L’utilisation de cette valeur nécessitait le recours au modèle animal. Or, nous avons démontré que le thorax du modèle porcin n’offrait pas le même comportement biomécanique lors de l’impact que le thorax de l’adulte jeune. Nous avons donc développé un critère, l’impulsion de pression intrathoracique maximale (PImax), basé sur la mesure de la pression intrathoracique lors de l’impact, et donc indépendant du comportement biomécanique de la paroi thoracique vis-à-vis de ses effets sur le poumon. Ce critère très bien corrélé avec le volume de la contusion pulmonaire, quelque soit le type d’impact thoracique balistique (ALRc ou BABT), a l’avantage de pouvoir être transposable aux autres moyens d’évaluations balistiques tels que les modèles numériques ou mécaniques de thorax, afin de s’affranchir de l’expérimentation animale / When non-penetrating, impacts on bulletproof jackets can lead to potentially lethal blunt injuries known as behind armor blunt trauma (BABT). Impacts of less lethal kinetic weapons (LLKW) can also lead to such injuries. To both improve the protection capabilities of the BPJ and better comprehend the ounding potential of the LLKW, we need to design a wounding criterion to predict the injury severity of ballistic blunt thoracic trauma. In one hand, this criterion has to be well correlated with the severity of the injuries, and in the other hand, it has to be easily used with all the LLKW and BPJ assessment systems in use. First, we defined the pulmonary contusion volume as the severity of the injuries. Studying the pulmonary contusion involves the use of animal experiments. But we demonstrated that the biomechanics of the chest wall are different in animals and young adults. Then, we developed the maximum pressure impulse criterion (PImax). As it is based on the intrathoracic pressure measure during the blunt impact, it is independent from the chest wall behavior. This criterion can be used with the other assessment tools as the numerical simulation mechanical chest surrogates. This can help to reduce the use of animal experiments, which is more and more expensive, heavy and questionable on the ethical aspect

L’association lésionnelle d’une contusion pulmonaire et d’un état de choc hémorragique est fréquente et constitue un réel chalenge thérapeutique. La prise en charge de ce choc va nécessiter une réanimation hémodynamique dans laquelle le remplissage vasculaire tient une place centrale. Mais dans ce contexte de poumon contus, il devra être raisonné car délétère sur le plan pulmonaire, notamment en terme d'oedème et d'altération de la compliance. Ce remplissage devra donc être titré, basé sur des objectifs tensionnels clairs et un monitorage hémodynamique fiable. L'utilisation de solutés à haut pouvoir d'expansion volémique (sérum salé hypertonique, colloïdes) présente un intérêt, de même que l'introduction précoce de vasopresseurs. Le monitorage hémodynamique permettra de conduire cette réanimation sur des objectifs de pression artérielle, sur des indices de précharge dépendance et sur la mesure de l'eau pulmonaire extravasculaire. Notre travail, basé sur des études expérimentales et cliniques, a pour objectif de caractériser les modalités actuelles de prise en charge d’une contusion pulmonaire, sur les plans hémodynamiques et respiratoires. / Pulmonary contusion is often associated with hemorrhagic shock, constituting a challenge in trauma care. For patients who have sustained lung contusions, fluid resuscitation should be carefully performed, because injured lungs are particularly vulnerable to massive fluid infusions with an increased risk of pulmonary edema and compliance impairment. Fluid administration should be included in an optimized and goal directed resuscitation, based on blood pressure objectives and hemodynamical monitoring. The use of fluids with high volume-expanding capacities (hypertonic saline, colloids) is probably interesting, as well as early introduction of vasopressors. Hemodynamic monitoring will allow to conduct resuscitation on blood pressure objectives, on preload parameters and on extravascular lung water measurement.Our work, based on experimental and clinical studies, objective to characterize the current modalities of ventilatory and hemodynamical aspect of pulmonary contusion care.