Patent ID: 8740802

Claim:
A system for measuring a blood pressure value from a patient, comprising: (a) a first sensor configured to generate a first time-dependent waveform indicative of one or more contractile properties of the patient's heart; (b) a second sensor configured to generate a second time-dependent waveform indicative of one or more contractile properties of the patient's heart; (c) a third sensor comprising an inflatable cuff configured to attach to the patient's arm, a pneumatic system configured to inflate and deflate the inflatable cuff, a pressure sensor, an analog-to-digital converter, a first microprocessor, a first serial transceiver, and a battery, the third sensor configured to generate a third time-dependent waveform indicative of pressure measured by the pressure sensor during inflation of the cuff, wherein heartbeat-induced pulses are indicated in the third time dependent waveform by variations in the measured pressure; and (d) a processing component configured to be worn on the patient's body and comprising a second microprocessor and a second serial transceiver, the processing component programmed to: (i) communicate through a cable worn on the patient's body with a third microprocessor and third serial transceiver comprised by the first sensor to receive a digitized version of the first time-dependent waveform; (ii) communicate with the first microprocessor and first serial transceiver comprised by the third sensor to receive a digitized version of the third time-dependent waveform; (iii) calculate a pulse transit time (PTT) calculated using a time difference between time-dependent features in digitized versions of the first and second time-dependent waveforms; (iv) receive the third time-dependent waveform and calculate therefrom systolic index (SYS index ), diastolic index (DIA index ), and mean arterial blood pressure index (MAP index ) calibration values and a patient-specific slope value (m) relating pulse transit time to mean arterial blood pressure, the calibration values determined from a digitized version of the third time-dependent waveform; and (v) calculate systolic and diastolic ratios (R SYS and R DIA ) according to the following equations: R SYS =SYS index /MAP index R DIA =DIA index /MAP index ; and calculate continuous systolic, diastolic, and mean arterial blood pressures from the pulse transit time, the calibration values, the systolic and diastolic ratios, and the patient-specific slope value.