Regional mucociliary removal of inhaled particles in smokers with small airways disease

Quantitative radioaerosol lung imaging was performed in 30 asymptomatic smokers selected on the basis of abnormal findings in pulmonary function tests of small airways. Regional clearance rates of inhaled 99mTc-labelled human serum albumin minimicrospheres (HAMM) were determined over upper, middle, lower, central, and peripheral anterior lung zones. In contrast with the findings in 20 nonsmokers without evidence of small airways dysfunction significant mucociliary clearance delay occurred in the peripheral and upper pulmonary regions. An aerosol distribution index (ADI) measures the homogeneity of distribution of inhaled particles in the lung. A significant difference in the mean values of ADI was found, indicating an abnormal uneven radioaerosol distribution pattern in the smokers with small airways disease.