Particle Deposition of Inhaled Aerosol Boluses in the Upper Human Airways

ABSTRACT

An inspired aerosol bolus of a defined volume injected at the end of an inhalation of particle free air was used to study particle losses and airway dimensions of the tracheo-bronchial tree. The penetration of the bolus into the lungs, the expired reserve volume, ERV, and the breathing posture were varied. From experiments with different breath-holding times after inhalation an effective airway diameter, D_A, was evaluated for a preset bolus penetration. With decreasing ERV and increasing penetration the determined D_A decreases. The lying posture of the subject yielded a smaller D_A than the sitting position. Effective airway diameters greater than 2 mm were found if the volumetric penetration of the bolus maximum is less than 50 cm³.