Abstract
Total respiratory impedance, from 1 to 20Hz, has been obtained by a modification of the forced oscillation method, in which a complex wave pressure imposed on the respiratory system and the flow induced were processed by Fourier spectral analysis. Parameters of a 2-compartment model were estimated on the complex plane by a phasor method in which all elements were represented as phasors and its frequency characteristics were displayed as phasor loci. It appeared from this study that: (1) The resistance and inertance of an endotracheal tube were 2.2cmH2O/l/sec., 0.07cmH2O/l/sec2. respectively. (2) After correcting for the effect of the tube, large airway resistance and inertance, small airway compliance, parenchymal resistance and inertance during enflurane anesthesia were found to be as follows; 1.2cmH2O/l/sec., 0.07cmH2O/lsec2, 0.02l/cmH2O, 1.6cmH2O/l/sec., 0.04l/cmH2O respectively. Estimates obtained with added external resistance was consistent with predicted effects.
