CLEARANCE IN SMALLER AIRWAYS OF INHALED 6-MU-M PARTICLES IN SUBJECTS WITH IMMOTILE-CILIA SYNDROME

In subjects with an inherited lack of mucociliary transport, so called immotile-cilia syndrome (ICS), coughing effectively clears particles deposited in larger airways of the tracheobronchial region. The presen t study investigated clearance in smaller airways of In-111-labeled 6- mu m (aerodynamic diameter) monodisperse Teflon particles in six subje cts with ICS. The particles were inhaled at an extremely slow flow, 0. 05 L/s. Theoretical calculations and experimental data in healthy subj ects using this slow flow support particle deposition mainly in smalle r ciliated airways, i.e., in bronchioli (generations 12-16). This cont rasts with the more centrally deposited pattern obtained using a norma l inhalation flow, 0.5 L/s. Lung retention was measured at 0, 24, 48, 72, and 96 h. Clearance war significant every 24 h measured over the f irst 72 h, whereupon it slowed down. The fractions of retained particl es were significantly (p < .01) larger than those found for healthy su bjects wing the slow inhalation flow and those found for ICS subjects using a normal inhalation flow. The results indicate that clearance of particles in smaller airways is incomplete and that cough cannot full y compensate for the lack of mucociliary transport in this region.