Deposition of inspired aerosol particles within the respiratory tract of patients with obstructive lung disease.

Total deposition of monodisperse aerosol particles in the size range between 1 micron and 3 microns was measured in patients with obstructive lung disease and in normal people using equal breathing conditions for both groups. It turns out that for breathing conditions at rest, deposition for patients is higher, especially in the case of 1 micron particle: A second breathing pattern similar to forced exercise, but including a breath holding interval of 6 s after inhalation, is applied to throw some light on the effect of time-dependent deposition mechanisms. The results show less differences between both groups, indicating that enhanced gravitational deposition during respiratory pauses compensates for differences in lung morphometry.