Developing a Computational Model of Lungs for Patients With Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is a condition secondary to direct or indirect insult to lungs, leading to acute respiratory failure, and is associated with high mortality. Majority of the ARDS patients require mechanical ventilation, which acts as double-edged sword. Ventilator induced lung injury (VILI) is considered secondary to high inspiratory pressure and cyclical opening during inspiration, and collapse during expiration as suggested by ARDS network clinical trials. Other mechanism for VILI exist secondary to heterogeneous ventilation. To enumerate these mechanisms leading to VILI, a computational fluids dynamics (CFD) study was performed in this study to explore the flow patterns and the pressure distribution in a human tracheobronchial airway model from third to sixth generation branches. The authors validated the computational methodology and analyzed the results to obtain velocity profiles in the primary and secondary flow directions. The study investigated the role of various flow velocities corresponding to Reynolds number (Re) from 100 to 2000 on the pressure drops along branches and bifurcation zones. The identification of secondary flow patterns was critical in understanding the development of asymmetric velocity profiles in the triple bifurcation geometry. The observed patterns in pressure drops and velocity profiles over the laminar flow regime pave the path toward further development of a numerical model to aid treatment for patients with ARDS.