A new method of analyzing the distribution of mechanical time constants in the lungs.

Abstract

When a sinusoidally varying pressure is applied to a system possessing an extremely large number of parallel pathways (assumed to be analogous to the lung), each with its own mechanical time constant (compliance x resistance), the complex compliance will be expressed in the integral transform of the distribution function of the mechanical time constant. The distribution function was obtained graphically using an approximation method to solve the integral transform. In normal subjects the log distribution function curve had a maximum point at a time constant of about 0.2 sec. and had a narrow and roughly symmetrical shape with respect to the time constant of the maximum, while the spectra in emphysematous patients showed a flat or trapezoidlike function with a maximum at a much higher time constant, about 1 sec. or more.