Non-invasive blood pressure data acquisition employing pulse transit time detection

Changes in the transit time of arterial blood pulse under an occluding cuff can be used as indicators of blood pressure. In this non-invasive method arterial blood pulse is detected by piezoelectric pick-up placed proximally and distally under the cuff. As the cuff pressure is lowered from the value above presumed systolic pressure a distinct signal is received by the distal pick-up at the moment when the artery opens for the first time. This moment defines systolic blood pressure. With the following decrease in cuff pressure it has been observed that the pulse transit time decreases monotonously. The inflection point in pulse transit time plot, where the reduction in pulse transit time ceases and subsequently will keep constant, is defined as the point of diastolic blood pressure