抄録
To simulate blood pressure measurement done by medical doctors, a new type stethoscope, which is a commercialy available stethoscope equipped with an eddy-current displacement sensor and a microphone, is developed. Using this stethoscope and impedance plethysmograph, pulse wave-forms and sounds distal to the cuff and volume change of the artery under the cuff were measured in various experiments. In some experiments, common blood pressure measuring process is adopted and, in other experiments, cuff-pressure is kept constant. From the experimental results, the following facts are known. 1) Blood flow rate coming from upstream in the collapsed artery under the cuff is not affected by arterial pressure distal to the cuff. 2) Always the same sounds are produced when experimental conditions are kept constant. 3) When sounds are heard there exist always steep wave fronts. From these facts, the true mechanism of Korotkoff sound generation is known to be hydrolic-jump formation at the wave front during pressure wave propagation through collapsed artery segment under the cuff.
