Numerical simulation of mucous layer formation effects on oxygen transfer phenomena from the respiratory membrane in pulmonary diseases

Abstract

Pneumonia, tuberculosis, asthma, cystic fibrosis, etc are known as acute pulmonary disorders which are leading to the inefficiency of the respiratory system. Owing to the infection and inflammation caused by diseases, the patient’s respiratory system is impaired and in the absence of proper treatment, it loses normal function. In the present study, to the modeling of oxygen transfer phenomena from the alveoli to the pulmonary capillary, the respiratory unit is considered as a simplified 3D model based on microfluidic device geometry. Then, by applying the physiological respiratory conditions on the presented model, the fluid flow and mass transfer equations for blood and airflow through the membrane in microchannels have been coupled and solved using Comsol Multiphysics software. The most remarkable result to emerge from the initial data is that the oxygen saturation has been in the physiological range and it confirms the proposed microfluidic model to the aim of this study. After attaining to the optimized geometrical model, by applying various conditions of the disease, including obstruction caused by infection and changes in concentration and thickness of the mucous layer formed on the respiratory membrane, the blood oxygenation during the diseases have been investigated. The results of the work show the changes in oxygen transferred from the alveoli to the lung capillaries during the inspiration process at different stages of obstruction under the influence of infection. It was pointed out that the effect of increasing of mucous layer thickness is greater than the mucous concentration in reducing blood oxygenation. According to the results, the discrepancy of the patient’s blood oxygen content relative to the physiological range is almost compensable by varying the oxygen concentration of the intake air. The oxygen concentration required to supply the blood oxygen deficit is proposed for several modes.