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This work is focused on the analysis of the response of the tracheal wall to different ventilation conditions. Thus, a finite element model of a human trachea is developed and used to analyze its deformability under normal breathing and mechanical ventilation. The geometry of the trachea is obtained from computed tomography (CT) images of a healthy man. A fluid structure interaction approach is used to analyze the deformation of the wall when the fluid (in this case, air) moves inside the trachea. A structured hexahedral-based grid for the tracheal walls and an unstructured tetrahedral-based mesh with coincident nodes for the fluid are used to perform the simulations with the finite element-based commercial software code (ADINA R & D Inc.). The tracheal wall is modeled as a fiber reinforced hyperelastic solid material in which the anisotropy due to the orientation of the fibers is introduced. Deformation of the tracheal walls is analyzed under different conditions. Normal breathing is performed assuming a sinus shape of the pressure at the inlet and air speed at the outlet based on real data which represent the inspiration and the expiration processes respectively. Mechanical ventilation is simulated as smooth square shape velocity airflow considering positive values of pressure using data from a mechanical ventilation machine. Deformations of the tracheal cartilage rings and of the muscle membrane, as well as the maximum principal stresses in the wall, are analyzed. The results show that, although the deformation and stresses are quite small for both conditions, forced ventilation does not exactly imitate the physiological response of the trachea, since with always positive pressure values the trachea does not collapse during mechanical breathing.  相似文献
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Endotracheal stenting is a common treatment for tracheal disorders as stenosis, cronic cough or dispnoea episodes. However, medical treatment and surgery are still challenging due to the difficulties in overcoming potential prosthesis complications. In this work we analyze the response of the tracheal wall during breathing and coughing conditions under different stent implantations. A finite element model of a human trachea was developed and used to analyze tracheal deformability after prosthesis implantation under normal breathing and coughing using a fluid-structure interaction approach (FSI). The geometry of the trachea is obtained from computed tomography (CT) images of a healthy patient. A structured hexahedral-based grid for the tracheal wall and an unstructured tetrahedral-based mesh with coincident nodes for the fluid were used to perform the simulations with a finite element-based commercial software code. Tracheal wall is modeled as a fiber reinforced hyperelastic solid material in which the anisotropy due to the orientation of the fibers is taken into account. Deformations of the tracheal cartilage rings and of the muscle membrane, as well as the maximum principal stresses in the wall, are analyzed and compared with those of the healthy trachea in absence of prosthesis. The results showed that, the presence of the stent prevents tracheal muscle deflections especially during coughing. In addition, we proposed a methodology to evaluate, through numerical simulations, the predisposition of the stent to migrate.  相似文献
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