Canine Pulmonary Input Impedance Measured by Transient Forced Oscillations

Abstract

We describe a transient forced oscillation method for measurement of the input impedance of excised canine lungs. The technique employs a single uncalibrated data channel to record short duration pressure transients incident upon and reflected from the airway opening, from which the input impedance up to 10,000 Hz is computed using lossy transmission line theory. Data acquisition time is less than 10 ms. The lung responses exhibit numerous resonances and anti-resonances below 10,000 Hz, and exhibit lung volume dependence. The branching structure of the airways and response of the airway walls appear to be important factors in the lung response.