Patent ID: 8560245

Claim:
A method for maintaining calibration of a continuous non-invasive blood pressure (CNIBP) measurement system, the method comprising: performing, using one or more processors, a calibration by: obtaining, for a subject, a reference blood pressure value, differential pulse transit time, and reference pulse wave data, the reference pulse wave data corresponding to one or more reference pulse waves; and calculating and storing coefficients of a continuous non-invasive blood pressure calculation formula based, at least in part, on the reference blood pressure value and the differential pulse transit time; obtaining, using one or more processors, subsequent pulse wave data characterizing one or more subsequent pulse waves of the subject and evaluating a recalibration condition based, at least in part, on a comparison of the subsequent pulse wave data to the reference pulse wave data, wherein the recalibration condition is based, at least in part, on at least one of a first feature, a second feature, and a third feature of the reference and subsequent pulse waves: the first feature comprising a pulse wave area of the reference and subsequent pulse waves; the second feature comprising a time difference, ΔT, between two internal features within the reference and subsequent pulse waves; and the third feature comprising a pulse wave shape of the reference and subsequent pulse waves; and if the recalibration condition is satisfied, performing a new calibration.