Typical Path Model of Tracheobronchial Clearance of Inhaled Particles in Rats

摘要

A mathematical description of particle clearance from the ciliated conducting airways (tracheobronchial region) of the lungs in rats was developed assuming that particles on the mucus blanket behave as a fluid and adhere to principles of fluid flow described by continuity equation. Effective particle transport velocities for given generations of airways were estimated from reported tracheal transport velocities. Using typical rat airway geometry and estimated particle transport velocities solutions of sets of rate equations for transport from each generation of airways were summed to estimate total particle clearance from the tracheobronchial region of the lung as a function of time. We used a wide range of aerosol particle size distribution data (MMAD ranging from 0.1 to 4.2 mm, and sg from 1 to 2.7) and concentration data from several investigators to predict short term, tracheobronchial clearance (retention) in rats and compared our predictions with their retention measurements. Based on an average of 17 simulations of tracheobronchial clearance the average difference between predicted and observed fractional retention of initial particle burden was 4.9%, with a tendency toward under prediction of clearance of particles > 3. 0 mm.