PULMONARY ARTERIAL IMPEDANCE ANALYSIS BY THE USE OF THE OSCILLATED ASSIST FLOW

Pulmonary arterial impedance is an important and interesting character istic that can be used to evaluate the physiological properties of the pulmonary vessel. However, power spectrum analysis of the pulmonary a rtery pressure and flow pattern have suggested that peak power in the relatively high frequency range (>10 Hz) is significantly low; thus, w e cannot analyze the vessel properties in the high frequency range. In this study, we used the newly developed vibrating flow pump (VFP), wh ich can generate oscillated blood now with a relatively high frequency (10-50 Hz) for right heart bypass, to evaluate the pulmonary arterial impedance pattern in the high frequency range. Acute animal experimen ts of the right heart bypass from the right atrium to the pulmonary ar tery using 6 healthy adult goats were performed. The flow pattern and pressure of the pulmonary artery, electrocardiograms (ECGs), and arter ial and right atrial pressures were continuously monitored during the experiments. Spectral analysis of the hemodynamic parameters using the fast Fourier transform (FFT) method was performed to evaluate the spe ctral properties. The coherence function, transfer function, and phase patterns were calculated to analyze the impedance pattern in the rela tively high frequency area. Previously, various investigators had trie d to analyze the impedance patterns of the pulmonary artery; however, they could not analyze the impedance patterns over 10 Hz because the s pectral patterns of the pulmonary flow do not have high power at high frequencies. These physiological analyses may be useful in designing t he optimal pulmonary circulation.