Doctor of Philosophy, The Ohio State University, 2012, Mechanical Engineering

The acute respiratory distress syndrome (ARDS) is a devastating lung disease. Patients with ARDS must be placed on a mechanical ventilator to survive. However, these ventilators also exacerbate the existing lung injury and as a result the mortality for ARDS is high (~25-40%). During ARDS, small pulmonary airways become occluded with fluid and mechanical ventilation of the fluid-filled lung involves the reopening of fluid-filled airways and the propagation of microbubbles over a layer of epithelial cells lining airway walls. Previous computational and experimental studies indicate that the large spatial gradients in pressure generated near the bubble tip may cause large-scale cellular deformation, rupture of the plasma membrane and cell necrosis. However, previous computational models do not account for the complex fluid-structure interactions that occur during in-vitro or in-vivo experiments. In addition, previous studies assumed rigid-wall conditions while pulmonary airways are in reality highly compliant and changes in airway wall mechanics may significantly influence the dynamics of airway reopening and cell deformation. Furthermore, the lung consists of a large network of bifurcating airways and different bifurcation patterns may influence both the hydrodynamics of airway reopening and cellular injury/deformation especially when the effect of gravity is considered. The objective of this particular thesis is to employ sophisticated computational fluid-structure interaction models to investigate how changes in the patient's biomechanical status such as airway wall compliance, fluid properties and bifurcation patterns influence the mechanics and hydrodynamics of microbubble induced cellular deformation and injury. We have developed several sophisticated computational models that can better represent the in-vivo or in-vitro conditions of compliant airway walls, fully coupled fluid-structure interactions and 3D structure of pulmonary airways with epithelial cells l (open full item for complete abstract)

Committee: Samir Ghadiali PhD (Advisor); Terrence Conlisk PhD (Committee Member); Yi Zhao PhD (Committee Member); Ronald Xu PhD (Committee Member) Subjects: Aeronomy; Biomedical Engineering; Mechanical Engineering