Three-dimensional computer modeling of the human upper respiratory tract.

Computer simulations of airflow and particle-transport phenomena within the human respiratory system have important applications to aerosol therapy (e.g., the targeted delivery of inhaled drugs) and inhalation toxicology (e.g., the risk assessment of air pollutants). A detailed description of airway morphology is necessary for these simulations to accurately reflect conditions in vivo. Therefore, a three-dimensional (3D) physiologically realistic computer model of the human upper-respiratory tract (URT) has been developed. The URT morphological model consists of the extrathoracic (ET) region (nasal, oral, pharyngeal, and laryngeal passages) and upper airways (trachea and main bronchi) of the lung. The computer representation evolved from a silicone rubber impression of a medical school teaching model of the human head and throat. A mold of this ET system was sliced into 2-mm serial sections, scanned, and digitized. Numerical grids, for use in future computational fluid dynamics (CFD) simulations, were generated for each slice using commercially available software (CFX-F3D), AEA Technology, Harwell, UK. The meshed sections were subsequently aligned and connected to be consistent with the anatomical model. Finally, a 3D curvilinear grid and a multiblock method were employed to generate the complete computational mesh defined by the cross-sections. The computer reconstruction of the trachea and main bronchi was based on data from the literature (cited herein). The final unified 3D computer model may have significant applications to aerosol medicine and inhalation toxicology, and serve as a cornerstone for computer simulations of air flow and particle-transport processes in the human respiratory system.