Patent ID: 8574161

Claim:
A system for monitoring a patient's blood pressure parameter, the system comprising: an optical sensor configured to attach to the patient and generate a time-dependent optical waveform representing a flow of blood within the patient; an electrode system configured to attach to the patient and generate a time-dependent electrical waveform representing activity of the patient's heart; a calibration system configured to attach to a portion of the patient's body and apply a pressure; and a processing component programmed to: i) determine a first set of pulse transit times, wherein each transit time within the set is a measure of a separation in time of a first feature of the time-dependent electrical waveform and a second feature of the time-dependent optical waveform, the first set of pulse transit times measured while the calibration system applies the pressure to the portion of the patient's body; ii) analyze the first set of pulse transit times with a mathematical model that processes a pressure-induced change in transit time to determine a calibration representing properties of the patient's blood circulatory system; and iii) calculate the blood pressure parameter from a second pulse transit time and the calibration, the second pulse transit time measured while the calibration system does not apply pressure to the portion of the patient's body.