Patent ID: 8602997

Claim:
A method for monitoring a blood pressure value from a patient, comprising: (a) applying a variable pressure to the patient's arm using a pressure-delivery system; (b) detecting a time-dependent pressure waveform representing the pressure applied to the patient's arm; (c) digitally filtering a portion of the time-dependent pressure waveform to determine a processed pressure waveform; (d) analyzing the processed pressure waveform to determine values for systolic blood pressure, diastolic blood pressure, and mean arterial pressure; (e) detecting a first time-dependent waveform comprising a first feature induced by the patient's heartbeat with a first sensor configured to attach to the patient; (f) detecting a second time-dependent waveform comprising a second feature induced by the patient's heartbeat with a second sensor configured to attach to the patient; (g) determining a pulse transit time from a separation in time between the first feature and the second feature; (h) determining a variation in the pulse transit time as a function of the pressure applied to the patient's arm; (i) processing the variation in pulse transit time to determine a relationship between pulse transit time and mean arterial blood pressure using a mathematical model that estimates an effective mean arterial pressure in the patient's arm that varies with pressure applied by the pressure-delivery system, wherein the effective mean arterial pressure is the difference between the mean arterial pressure determined during step (d) and a pressure-induced blood pressure change, wherein the pressure-induced blood pressure change is defined by the following equation or a mathematical derivative thereof: Δ MAP ( P )= F ×( P applied −DIA INDEX ) where ΔMAP(P) is the pressure-induced blood pressure change,P applied is pressure applied by the pressure-delivery system during inflation, DIA INDEX is the diastolic pressure determined from the processed pressure waveform, and F is a mathematical constant; and (j) analyzing a pulse transit time determined when no pressure is applied to the patient's arm with the pressure delivery system, the relationship between pulse transit time and mean arterial blood pressure, and the blood pressure values determined from the processed pressure waveform in step (d) to determine a blood pressure value when no pressure is applied to the patient's arm with the pressure delivery system.