脈動流における血液の電気特性

抄録

It is well known that when blood flows steadily, the electrical impedance of blood changes from its resting value. The impedance change of flowing blood is principally due to the orientation of red blood cells, if blood flows steadily. However, the effects of pulsatile flow upon the impedance of blood have not yet been discussed. When the blood flow is pulsatory, the electrical impedance of blood varies with time. The following, are discussed :
(1) the impedance waveforms of sinusoidally flowing blood in rectangular conduit,
(2) the relations between the impedance change and the flow rate of both the sinusoidal and the pulsatile flows, and
(3) the relations between the impedance change and the frequency of the various flows. From the results :
(1) it is concluded that the resistance change of blood is mainly caused by the orientation of red blood cells;
(2) the waveform of the resistance change of the sinusoidally flowing blood is similar to the fullwave rectification of sinusoidal flow, because the resistance can only change unidirectionally;
(3) when blood flow is pulsatory, not only the resistance change is pulsatory, but the mean resistance also changes simultaneously, because the orientation of red blood cells can not follow the rapid change of flow, therefore, the pulsatile and the mean resistance changes are affected by both the amplitude and the frequency of pulsatile flow;
(4) the relaxation time of the orientation is about one sixth of a second;
(5) both the pulsatile and the mean resistance changes due to the orientation of red blood cells in aorta are about from 4% to 10%; and
(6) the resistance change due to the orientation of red blood cells in both vein and capillary is much less than that in aorta.