The Effects of Lung Mechanics on the Deposition of Inhaled Particles in the Human Lung Upper Airways – A Computational Fluid Dynamics (CFD) Approach

(1) KAMBIZ NAZRIDOUST, (2) Bahman Asgharian, (3) Owen Moss, (4) Jeffry Schroeter, (5) Goodarz Ahmadi

(1) SimuTech Group, (2) Applied Research Associates, (3) POK Research, (4) The Hamner Institutes for Health Sciences, (5) Clarkson University

     Abstract Number: 278
     Last modified: May 3, 2010

Abstract
Assessment of the dose and distribution of inhaled particles in the lung allows linking local particle deposition to biological responses. Despite the prevalence of CFD modeling of airflow, inadequate attention has been given to lung mechanics and boundary conditions that drive airflow through the lung. The objective of this study is to investigate particle deposition in the human lung and examine the effect of various imposed boundary conditions on the computer model predictions. A model of human upper airways consisting of the nasal cavity, larynx, and first 7 generations of the human tracheobronchial tree was reconstructed based on CT-scan images. The influence of 3 different boundary conditions was investigated: (1) Prescribed nostril mass flow and atmospheric outlet pressure. This corresponded to the case of flow being driven by viscous resistance in the selected geometry. (2) Atmospheric nostril pressure and outlet flow rates based on uniform lobar expansion by neglecting nonuniformity of lung compliance. (3) Atmospheric nostril pressure and outlet flow rates based on airway resistance and lung compliance of the distal airways. Flow fields were calculated for a 2-second inhalation time. Particle trajectories were examined using a Lagrangian tracking method. Particle losses by inertia, gravity, and Brownian motion were included in the analysis. Spherical particles ranging from 1nm to 10micro-m were inserted at the nostril inlet face and particle deposition fraction and distribution pattern were evaluated. While the flow fields exhibited similar features, the different boundary conditions significantly affected particle deposition patterns. The findings of this study are expected to improve computational assessment of therapeutic drugs and human health risk from exposure to airborne materials.