Diffusion-dependent contribution to the slope of the alveolar plateau.
Two healthy subjects performed single breath tests, the inspired gas containing 90% O2, 5% He and 5% SF6. The slope of the alveolar plateau was computed for N2, HE and SF6. The following experimental conditions were considered variable: (1) preinspiratory lung volume (PILV) with inspired volume (VT) equal to 1 L, (2) VT with PILV equal to functional residual capacity (FRC) with and without 10 sec of breath-hold (BH) time, (3) VT with PILV = FRC + 1 L, (4) flow with VT = 1 L and PILV = FRC with and without 10 sec end inspiration BH and (5) BH time with VT = 1 L and PILV = FRC. The slope dependence on the different variables was compared with simulations performed with two multibranch point models of the human acinus with different asymmetries. The model simulations give a coherent picture of all the experimental observations. The present work gives support to previous analyses which suggest that inter-dependence of transport by convection and diffusion in the periphery of the lung is a major component of the slope of the alveolar plateau.
Paiva
M
M
Institute of Interdisciplinary Research, Erasme Hospital, Free University of Brussels, Belgium.
Verbanck
S
S
van Muylem
A
A
D000328:Adult; D001944:Breath Tests; D004058:Diffusion; D005260:Female; D006801:Humans; D008176:Lung Volume Measurements; D008297:Male; D008954:Models, Biological; D011650:Pulmonary Alveoli / Q000502:physiology*; D011659:Pulmonary Gas Exchange; D012119:Respiration