Anatomical factors of human respiratory tract influencing volume flow rate and number of particles arriving at each bronchus

摘要

Inhalants, such as bronchodilators, are often used to treat asthma. Numerical simulation can be applied to quantitatively evaluate the transport and deposition of medicinal particulates in the respiratory tract. In this study, numerical simulation of an airflow including particles in a tracheobronchial model was conducted based on a computed tomography (CT) image of a human respiratory tract, and then the anatomical factors of the airway that influence the volume flow rate and the number of particles arriving at each bronchus were investigated. The oral cavity, pharynx, larynx, trachea, and infra-thoracic central airways of up to seven generations were modeled from the CT image. The airflow was simulated by large eddy simulation using OpenFOAM ver. 2.3.1. The particle transport was calculated in a Lagrangian manner. Statistical analysis was performed on the results of computational fluid dynamics simulation. It was found that the cross-sectional area of the outlet boundary, the total distance of the center line of the respiratory tract between the carina and the outlet boundary, and the angles between each bronchus and the trachea have large influences on the volume flow rate at each outlet. These influences increase almost linearly as the inhalation flow rate increases. The outlet area and the total angle markedly influenced the number of arriving particles. Larger particles are more likely to be influenced by the angle at which the direction of the particle is deflected. As the inhalation flow rate increases, the influence of the total angle increases and that of the outlet area decreases in all particle conditions. (C) 2019 Nalecz Institute of Biocybernetics and Biomedical Engineering of the Polish Academy of Sciences. Published by Elsevier B.V. All rights reserved.