To perform the instantaneous radial blood pressure measurement based on the volume-compensation method, a reference value for the servo control (
V0) has to be determined in the initial stage of the measurement. The volume-oscillometric method with a photo-plethysmography has previously been used to determine the
V0. However, an operational time by this method requires more than 30 s. In order to reduce this time and/or to reset quickly the
V0 when it suddenly changes during the measurement, we have developed a new method to determine the
V0 more quickly. In this new method, sinusoidal vibrations having a frequency of 20 Hz and an amplitude of 10 mmHg are superimposed on the cuff pressure that is increasing by the rate of 20 mmHg/s. The
V0 can be determined by detecting a mean value of the photo-plethysmographically measured arterial volume showing the maximum volume amplitude corresponding to the pressure vibration component. The validity of this method was evaluated using twenty healthy subjects by comparing with the volume-oscillometric method as a reference. The results indicated that the present method could determine the
V0 with very high accuracy: The average of the ratio of
V0 determined by these two methods was 1.002 with standard deviation of 0.012. This paper also described the effects of the levels of blood pressure, pulse rates and the circumferences of the wrists on the determination of
V0, together with the resetting of
V0 during the instantaneous blood pressure measurement when the initial
V0 was suddenly changed due to an artificial operation.
抄録全体を表示