Journal of Applied Physiology, Vol 58, Issue 3 802-811, Copyright © 1985 by American Physiological Society
Model simulation of single-breath washout of insoluble gases from dog lungs
C. Hook, M. Meyer and J. Piiper
Intrapulmonary gas mixing by convection and diffusion is analyzed on the
basis of various analog lung models incorporating singly or in combination
series inhomogeneity, parallel inhomogeneity, intercompartmental diffusion,
sequential inspiration, and sequential expiration. The slope of the
alveolar plateau of insoluble gases is used as an indicator for incomplete
gas mixing. By use of the models, we have attempted to simulate
experimental results obtained in artificially ventilated dog lungs with
simultaneous single-breath washout of He and SF6 (Meyer et al., J. Appl.
Physiol. 55: 1795-1802, 1983). Sufficient agreement with experimental data
is obtained only when diffusion between serial-parallel compartments and
sequential expiration are incorporated, the first being mainly responsible
for separation of He and SF6, the latter for the slope of the alveolar
plateau of these gases. A combined operational model comprising two
parallel compartments connected to a mixing compartment, with both
convective and diffusive gas transport between the compartments, could
account for most of the experimental observations.
