REPEATABILITY OF AIRWAY DEPOSITION AND TRACHEOBRONCHIAL CLEARANCE RATE OVER 3 DAYS IN CHRONIC-BRONCHITIS

Previous investigations on tracheobronchial clearance in chronic bronc hitis or chronic obstructive pulmonary disease (COPD) have usually ref erred to measurements during a short time-period, i.e. a few hours, Th e purpose of this study, therefore, was to study regional particle dep osition and tracheobronchial clearance during 72 h. In 14 patients wit h chronic bronchitis clearance of In-111-labelled 3.6 pm Teflon partic les and lung function were measured on two occasions, with an interval of 2 weeks, Lung retention of test particles was measured at 0, 24, 4 8 and 72 h using a profile scanner, The weight of expectorated sputum samples was measured after the two clearance measurements, The particl e retentions at all time-points were reproducible, as seen from the tw o measurements (r > 0.90). The fast clearance phase was completed with in 72 h, No correlation between sputum volume and clearance was seen, There was a significant negative correlation between airway resistance and the 72 h retention (r = -0.66), and an even better correlation be tween specific airway resistance and the 72 h retention (r = -0.82), i ndicating more central deposition in obstructed airways, There was no significant correlation between lung function tests reflecting smaller airways and the 72 h retentions, Deposition data agreed well with the oretical calculations and experimental data in healthy subjects, In sp ite of earlier findings that mucociliary transport is usually severely impaired in chronic bronchitis and COPD, the present results indicate that overall tracheobronchial mucus clearance in these patients is fa irly effective, probably due to a productive cough, Alveolar depositio n may be estimated by measurements of the 72 h retention in subjects w ith chronic obstructive pulmonary disease, The 72 h retention is depen dent mainly on the calibre of larger airways. The present method of st udying airway clearance during 3 days is highly reproducible.