TIME-VARYING PULMONARY ARTERIAL INPUT IMPEDANCE VIA WAVELET DECOMPOSITION

Wavelet decomposition is proposed as a novel approach for determining pulmonary arterial input impedance throughout the breathing cycle. The canine pulmonary arterial input impedance was evaluated throughout th e ventilatory cycle at 5, 10, and 15 cmH(2)O of positive end-expirator y pressure. The impedance spectrum was obtained by Fourier transformat ion of wavelets generated by decomposing the pulmonary arterial pressu re and flow waveforms. With wavelet decomposition, each heart beat is viewed individually as a transient pulse rather than as an interval wi thin a continuous function of pressure and flow. The advantage of usin g this approach is the ability to obtain stable estimates of input imp edance spectra with high-frequency resolution over the entire frequenc y range with only a limited data set of pressure and flow decomposed t o wavelets as short as singular extrapolated cardiac cycles. This meth od was used to define the changes of input impedance that occur during the ventilatory cycle. Results show that the impedance spectrum under goes notable changes during the breathing cycle and demonstrate the ut ility of the proposed method.