Patent ID: 6852083

Claim:
A method of determining whether to recalibrate blood pressure monitor which calculates blood pressure using a calibration signal from a calibration device indicative of an accurate measurement of the blood pressure of a patient and using a continuous signal from a sensor indicative of a continuous noninvasive measurement of one or more attributes of one or more waves propagating along an artery of the patient, the method characterized by: approximating a function relating a change in a trigger parameter to a change in a pressure-velocity relationship, wherein the pressure-velocity relationship is used to noninvasively determine the blood pressure of a patient; calibrating the pressure-velocity relationship using a calibration signal indicative of a first accurate measurement of the blood pressure, and using a continuous signal indicative of a continuous noninvasive measurement of one or more attributes of one or more waves propagating along an artery of a patient; calculating a first value of the trigger parameter from the continuous signal; calculating the blood pressure using the pressure-velocity relationship and the continuous signal; calculating a second value of the trigger parameter from the continuous signal; calculating a change in the pressure-velocity relationship by applying the pressure-velocity relationship and the first and second values of the trigger parameter to the function; and when the change in the pressure-velocity relationship exceeds a threshold value, recalibrating the pressure-velocity relationship using the continuous signal and using a calibration signal indicative of a second accurate measurement of the blood pressure.