Patent ID: 7662102

Claim:
A method for measuring the arterial instantaneous blood pressure and compliance, comprising: a searching step: finding the critical depth λ s when P s = P b and determining P s and λ s using an actuator to impose a pressure on the skin, a pressure sensor to measure a skin mean blood pressure P s , and a displacement sensor to detect the depth λ s under the pressure, then using the pressure sensor to measure the peak-to-peak pressure value, where the above-mentioned procedure is repeated until the maximum peak-to-peak value is reached, with the corresponding depth being the critical depth λ s and the mean blood pressure measured at the skin being equal to the arterial mean blood pressure P b ; wherein P s is the mean blood pressure measured at the skin, P b is the arterial mean blood pressure, and λ s is the critical depth of the skin; a controlling step: using the pressure sensor to monitor the blood pressure change ΔP s transmitted from the artery to the skin when the arterial blood pressure changes by ΔP b at the critical depth λ s , using the actuator to change the depressed depth of the skin for generating the corresponding displacement change Δλ s so that the blood pressure change at the skin ΔP s approaches zero, in which case the muscle tissue compliance remain invariant, the tissue stiffness K t being equal to the tissue impedance Z t and thus making the mean blood pressure at the skin P s and the arterial mean blood pressure P b remain equivalent, where the displacement change Δλ s of the actuator detected by the displacement sensor is the variation in the arterial blood vessel diameter; wherein ΔP b is the difference between the arterial blood pressure and the mean blood pressure, Δλ s is the displacement change from the critical depth λ s for the arterial mean blood pressure change of ΔP b ; an identifying step: simulating the artery vessel as a second-order system with mass, damping, and stiffness and performing system identification to obtain blood vessel parameters M v , D v , and K v as well as the artery impedance Z v ; an estimating step: transmitting the detected signal to a controlling unit for computations, using the mean blood pressure at the skin P s , the artery impedance Z v , and the arterial blood vessel diameter change Δλ s to estimate the arterial instantaneous blood pressure {circumflex over (P)} b , and using the arterial instantaneous blood pressure {circumflex over (P)} b and the diameter displacement change Δλ v to make a plot of the arterial dynamic compliance at the critical position.