Cyclic Variation of Doppler Power as a Function of Hematocrit and Vessel Wall Compliance

-In order to better understand the relationship abnormalities, a systematic study of a11 factors that may affect between the power of the Doppler spectrum and blood flow the Doppler power is required. In this study, three important factors were investigated in pifro using a mock flow loop: a) the pulsation rate of the flow, b) the hematocrit of blood and c) the vessel wall compliance. The results may be useful for the development of a noninvasive method for assessing blood vessel wall compliance and fetal hematocrit in utero. The dB as the pulsation rate increases from 20 to 55 beatslmin. results show that the peak Doppler power decreases 1.5 to 2 The cyclic variation of the Doppler power is between 2.3 and 6.1 dB at 20 beatsimin, depending on the hematocrit, but it drops to 1.6-2.4 dB at 55 beatslmin. Moreover, both the time delays of the cyclic variation from the peak systole and the function of the hematocrit. This is more evident in compliant amplitude of the peak of the power are observed to be a vessels at the low beat rate of 20 beatsimin. When the vessel becomes more compliant, the Doppler power peak is shifted from the early to the late systole. These results suggested that simultaneous measurements of the time shift of the Doppler power peak relative to the velocity waveform and the magnitude of Doppler power cyclic variation may yield indication as to the value of the hematocrit and vessel compliance.