Patent ID: 9161700
Filing Date: 2015-10-20
Classification: A61B

Abstract:
1. A method for body worn monitoring a blood pressure value from a patient who may be ambulatory, comprising using a body-worn system including a microprocessor capable of continuous non-invasive blood pressure monitoring for: (a) detecting a time-dependent optical waveform comprising a pulse induced by the patient's heartbeat with an optical sensor configured to attach to the patient; (b) detecting a time-dependent electrical waveform comprising a QRS complex induced by the patient's heartbeat with an electrical sensor configured to attach to the patient; (c) determining a pulse transit time, which is a measure of a separation in time between a portion of the pulse comprised by the time-dependent optical waveform and a portion of the QRS complex comprised by the time-dependent electrical waveform; (d) determining a heart rate from portions of QRS complexes in the time-dependent electrical waveform; (e) determining a mathematical relationship between heart rate, or a first parameter calculated therefrom, and pulse transit time, or a second parameter calculated therefrom; (f) determining an estimated pulse transit time from a heart rate and the mathematical relationship between heart rate and pulse transit time; and (g) analyzing the estimated pulse transit time and a patient-specific slope value (m) relating pulse transit time to mean arterial blood pressure, wherein m is determined from a pressure-dependent indexing blood pressure measurement made during inflation of an arm-worn blood pressure cuff that comprises an inflatable bladder and an internal pressure sensor, to determine a blood pressure value from the patient.