Particle Deposition in Casts of the Human Upper Tracheobronchial Tree

Abstract

Particle deposition in the human tracheobronchial tree was studied by means of hollow Silastic casts extending from the trachea through the segmental bronchi. Tagged, monodisperse test aerosol was drawn at a constant inspiratory flow rate through the casts. Total deposition was low for particles with aerodynamic diameters below 3.5 µm and increased rapidly with increasing diameter between 3.5 and 12.2 µm. Deposition per generation increased with depth down to the segmental bronchi. Most of the impaction occurred at the bifurcations. At the tracheal bifurcation, the greatest particle accumulation was found along the carina. The reported distribution of sites of bronchial carcinoma was related to the distribution of sites of impaction observed in this study.