Journal of Applied Physiology, Vol 38, Issue 3 427-435, Copyright © 1975 by American Physiological Society
Simulation of frequency dependence of compliance and resistance in healthy man
H. Bobbaers, J. Clement, J. Pardaens and K. P. Woestijne
The frequency dependence of effective compliance, Ceff, and resistance,
Reff, are reproduced by means of a two- or four-compartment linear
mathematical model with pleural pressure as a sinusoidal input. The model
simulates the mechanical properties of lung parenchyma, alveolar gas,
bronchial wall, and cheeks, as well as the distribution of gaseous
resistances and inertances within the airways. Values, representative for a
young healthy adult, are assigned to these various parametersmit appears
from this study: 1) that the gas inertance produces a very marked increase
of Ceff, noticeable already below 1 cycle/smto obtain a frequency
independence of Ceff between 0 and 2 cycles/s, it is necessary to introduce
a marked inhomogeneity in the model. 2) Such an inhomogeneity is realized
by simulating a pleural pressure difference of 6 cmH2O between the
compartments of the bialveolar model. It can be shown that this corresponds
to a total pleural pressure difference of about 9 cmH2O in a model
consisting of an infinite number of compartments. 3) The influence of the
compressibility of alveolar gas and of mechanical properties of the
bronchial wall and of the cheeks on Ceff and Reff is small or negligible.
