Method and device for controlling the cuff pressure in measuring the

Abstract

Arrangement for controlling the cuff pressure in the indirect, non-invasive, continuous measurement of blood pressure in a finger by using a photo-electric plethysmograph in a fluid-filled pressure cuff, an electronic control circuit and an electric pressure valve, the cuff pressure being controlled by the plethysmographic signal in closed-loop operation by means of a servo-reference level, so that the arterial volume is maintained at a pre-adjusted value. For initial adjustment, the cuff pressure or the servo-reference level as initial adjustment quantity is automatically changed continuously in the control range by means of a control waveform supplied to the electronic control circuit, that thereby the peak-through amplitude of the pulsatile plethysmographic signal or cuff pressure signal is detected time and again, and compared with the preceding peak-through amplitude. The biggest value thereof in the control range and the associated value of the cuff pressure at servo-reference level are stored, which value of cuff pressure or servo-reference at the end of the initial adjustment is used as set value for the measurement of the blood pressure.