Particle deposition in a hollow cast of the human tracheobronchial tree

The deposition of particles within the human airways was studied using a hollow silicone rubber cast of the larynx and tracheobronchial tree which extended to bronchi of approximately 0.2 cm dia. The cast was exposed to radioactively tagged, ferric oxide aerosols, having mass median aerodynamic diameters ranging from 2.5 to 8.1 μm, at three constant 'inspiratory' flow rates. The detection system was designated for the determination of deposition within airways of all sizes and at various branch levels, and to allow selective measurements of the deposited activity within bifurcation and length regions of individual bronchi. Deposition efficiencies were determined and classified according to branch generation. Bifurcations were sites of preferential deposition over the range of particle sizes and flow rates used; bifurcation deposition generally peaked in generation 3. (author)