Journal of Applied Physiology, Vol 43, Issue 3 391-396, Copyright © 1977 by American Physiological Society
Role of conducting airways in partial separation of inhaled gas mixtures
K. Horsfield, A. Davies and G. Cumming
A positive (hollow) cast of the bronchial tree was made from a pig's lung.
Gas mixtures containing sulfur hexafluoride (SF6) and helium (He), and SF6
and argon (Ar), were blown down the cast at two different flows, the cast
having first been filled with air. Gas was sampled by a mass spectrometer
probe from 1-mm-diam branches situated on short, medium, and long pathways.
The front of the SF6 appeared in advance of the fronts of the He and the
Ar. This relative advancement was greater a) with the SF6/He mixture than
with the SF6/Ar mixture; b) at slower flows; and c) on longer pathways.
With reverse flow up the cast using SF6/He there was little differences
between the arrival times of the two gas fronts at either flow. These
results could be explained by the effects of Taylor dispersion on gases
having different diffusion coefficients.
