ANALYSIS OF ULTRASONIC BLOOD RHEOGRAM BY A BAND PASS FILTER

The detected sound of Doppler's beat obtained by directing a continuous ultrasonic wave of 5 mc into an artery was separately recorded in four chan nels, namely 1000 to 2000 cps, 500 to 1000 cps, 250 to 500 cps, and 100 to 250 cps, by three band pass filter units. The zero-crossing number of the detected sound was converted into an analog quantity, and an envelope power meter was applied to record the envelope by integrating the power of the detected sound (F-E system). The incorporation of these two methods provided more detailed information of circulatory dynamics, and some results about functional and organic circulatory changes were presented. 1. A characteristic pattern was obtained in the analyzed pattern of each of various arteries. Two peaks were generally recorded in the systole and one in the diastole. 2. The analyzed wave pattern of the carotid flows of cerebral arteriosclerotic cases showed, in general, a slowed blood flow, especially at the first peak of the systole and diastole. 3. The common and external carotid, subclavial, abdominal, and occasionally internal carotid artery of healthy young subjects gave waves of short duration at the beginning of systole in the 100 to 250 cps channel. The wave is considered to be originated from vascular walls. 4. It is possible to detect the changes in circulatory dynamics under various conditions such as postural change, Valsalva's maneuver, changes in blood gas tension, or temperature change. The method is sensitive enough to detect the difference between both sides of cerebral circulation. © 1968, SAGE Publications. All rights reserved.