Airway Deposition of Inhaled Particles in Healthy and Pathological Subjects

Probabilities for deposition of aerosols in the human respiratory tract can be predicted by calculation models widely based upon ventilatory airflows, lung dimensions and anatomical features. A study of the impact of impaired lung function on airway deposition was performed on three groups of subjects: 18 healthy non-smokers, 15 patients with moderately restrictive lung function, and 15 patients with moderately obstructive lung function. Total deposition of an aerosol inhaled through the mouth at identical ventilation rates for all subjects and containing three sizes of monodisperse inert particles. (1.2, 2.3 and 3.3 µm aerodynamic diameter) was measured by comparing inhaled and exhaled concentrations by laser velocimetry. Results were significantly higher in all the patients than in the healthy non-smokers. In restricted patients, Total Lung Capacity, Functional Residual Capacity, and Forced Expiratory Volume in one second (FEVI) presented significant inverse correlation coefficients with deposition. In obstructive patients, inverse correlation was observed only with FEVI.