Abstract
ABSTRACT
Human airway dimensions of ten healthy subjects were investigated by means of monodisperse aerosols as function of the volumetric lung depth (VLD). A non-invasive single breath aerosol inhalation technique was used (Heyder, 1989) with two different particle sizes (0.8 μm and 1.5 μm). The method is based upon measurements of gravitational losses of the inhaled particles in the respiratory tract during respiratory pauses. From the loss rate of the particles at different VLDs during breath-holding and their known terminal settling velocity (vs), EADs can be calculated. EAD-values have been determined by holding the breath at a lung volume of 1000 cm3 above functional residual volume (FRC). Highly significant (p < 0.005) differences were found between the EADs obtained with the two particle sizes. These differences can be explained by a mixing mechanism during the breathholding period caused by cardiogenic flow oscillations.
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