Journal of Applied Physiology, Vol 50, Issue 6 1293-1299, Copyright © 1981 by American Physiological Society
Oscillatory flow and quasi-steady behavior in a model of human central airways
A. S. Slutsky, G. G. Berdine and J. M. Drazen
We studied biased oscillatory flow in a model of human central airways to
examine under what conditions oscillatory flow deviated from steady flow.
Although the steady flow resistance of the model was 25% less than the
oscillatory flow resistance of the model at 15Hz, the overall inertance of
the model did not change over the range of frequencies from 5 to 15 Hz,
suggesting that frequency-dependent inertial distortion of velocity
profiles did not alter central airway pressure-flow relationships over this
frequency range. In a given terminal branch of the model, instantaneous
oscillatory flow at 2 and 5 Hz could be predicted well from the steady flow
distribution, but with increasing frequency the oscillatory flow from the
branch deviated more from the steady flow predictions. A significant
component of this deviation was due to a phase shift between predicted and
measured oscillatory flow. We conclude that the major frequency-dependent
behavior flow in the human central airways is a phasic redistribution of
flow above 7 Hz, resulting from the asymmetric distribution of inertances
in this structure.
