Journal of Applied Physiology, Vol 48, Issue 2 313-319, Copyright © 1980 by American Physiological Society
Viscosity and density dependence during maximal flow in man
B. A. Staats, T. A. Wilson, S. J. Lai-Fook, J. R. Rodarte and R. E. Hyatt
Maximal expiratory flow curves were obtained from ten healthy subjects
white breathing air and three other gas mixtures with different densities
and viscosities. From these data, the magnitudes of the dependence of
maximal flow on gas density and viscosity were obtained. The scaling laws
of fluid mechanics, together with a model for the flow-limiting mechanism,
were used to obtain a prediction of the relationship between the density
dependence and the viscosity dependence of maximal flow. Although the data
for individual subjects were too variable to allow a precise comparison
with this prediction, the relationship between the mean density dependence
and the mean viscosity dependence of all usbjects agreed with the theoretic
prediction. This agreement supports the assumption, which is frequently
made, that flow resistance rather than tissue visoelasticity is the
dominant contributor to peripheral resistance. Information on the
relationships between the pressure drop to the flow-limiting segment and
flow, gas density and viscosity, and lung volume were also obtained.
