Hemodynamics in the pulmonary artery of a patient with pneumothorax.

Pneumothorax is characterized by lung collapse and an alteration of lung geometry, resulting in alterations of the pulmonary artery blood flow. Though many clinical studies and animal experiments have investigated the effects of pneumothorax on the hemodynamics of pulmonary arteries, its precise effects remain unclear. In this patient-specific study, we investigated the effects of lung deformation and vascular resistance increases due to pneumothorax on the pulmonary blood flow during the acute phase and after recovery. Arterial geometry was extracted up to the fifth generation from computed tomography images, and reconstructed. Computational fluid dynamic analysis was performed, for an unsteady laminar flow with resistance at the outlets, in a reconstructed domain. The results demonstrated a change in flow structure during systole between the acute phase and recovery, and were associated with variations in the flow rate ratio between the right and left lungs. We observed a parabolic-like decrease of the volume flow rate ratio in the affected lung as the resistance increased. Thus, the systemic artery blood oxygenation will rely more on the unaffected lung leading to improved oxygenation of the blood under high resistance in the affected lung. These findings are significant in our understanding of ventilation function under a pneumothorax.