Modeling aerosol bolus dispersion in human airways

Aerosol bolus dispersion has attracted attention due to its value in non-in vasive clinical diagnosis of lung function and also due to its influence on particle deposition in the pulmonary region of the lung. The two salient o bservations from bolus dispersion experiments are that (1) dispersion incre ases linearly with inhaled volume and (2) dispersion is higher in a disease d lung than a healthy one for similar volume penetration. A number of plaus ible causes for dispersion have been proposed and discussed in the literatu re. However, a clear physical mechanism responsible for dispersion is still not available. Using a simple hypothesis for convective mixing, we propose an approximate physically based model to quantify bolus dispersion in the human airways. We then develop a computational model to simulate dispersion in the human lung and compare the model predictions to experimental data. This simple model, employing no adjustable parameters, predicts many observ ations of bolus dispersion. (C) 1999 Elsevier Science Ltd. All rights reser ved.