INDIRECT METHOD OF BLOOD PRESSURE MEASUREMENT FOR THE BIOFEEDBACK CONTROL OF BLOOD PRESSURE

Abstract

In this paper, a new indirect blood pressure measurement method for Biofeedback control of blood pressure is discussed. For the purpose of Biofeedback control of blood pressure, it is necessary to continuously measure the change of blood pressure through a experiment. Suitable method for this purpose have never been developed. Experimental results on blood pulse velocity reported by many researchers show that the pulse wave velocity is greatly affected by diastolic blood pressure. Therefore, pulse wave velocity is used for the estimation of blood pressure. It is also wellknown that the time difference between two waves in the pulse waveforms depend on the pulse wave velocities. Therefore, we can get the informations about blood pressure from the interval between these two waves. To estimate the change of blood pressure from the change of interval, it is necessary to know the relation between the blood pressure and the interval for each patient. The pressure wave is transcutaniously detected at the dorsal artery of foot. For the measurement of this interval, autocorrelation function of measurement pressure wave 1s calculated in real time by a micro computer. Before experiment of biofeedback, this interval is calibrated by usual cuff method at various blood pressure. From these results, we can see that the change of the interval is inversely proportional to the change of blood pressure. Therefore, the blood pressure can be estimated from the interval within the measurement accuracy of 2 or 3 mmHg.