Continuous, non-invasive technique for determining blood pressure using a transmission line model and transcutaneous ultrasound measurements
First Claim
1. A method for continuously and non-invasively monitoring blood pressure of a patient, the method comprising the steps of:
- positioning a first ultrasound sensor and a second ultrasound sensor aligned with a blood vessel of the patient, the first and second ultrasound sensors being operable to determine the diameter of the blood vessel and the flow rate of blood through the blood vessel;
obtaining a first blood flow rate determined from the first ultrasound sensor, a second blood flow rate determined from the second ultrasound sensor, and a blood vessel radius;
utilizing a transmission line model to represent the blood vessel, where the voltage at each node of the transmission line model corresponds to the blood pressure, the transmission line model including an input current source and an output current source positioned between an RLC ladder network, wherein the input current source is the first blood flow rate and the output current source is the second blood flow rate;
developing a series of state variable equations based on the transmission line model; and
inputting the obtained first blood flow rate, the second blood flow rate and the blood vessel radius into a Kalman filter;
utilizing the Kalman filter to estimate the state variables of the transmission line model;
using a transmission-line-based computation to estimate the blood pressure.
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Abstract
A method and technique for the continuous, non-invasive measurement of blood pressure. The blood pressure measurement technique of the present invention utilizes ultrasound measurements to determine the diameter of the blood vessel in which the blood pressure is being measured as well as the flow rate of blood at both an input point and an output point along the blood vessel. The system utilizes a transmission line model to relate various blood vessel measurements with electrical components. The transmission line model, in combination with data management techniques including state variable representations and Kalman filtering, is used to develop a blood pressure measurement in real time.
46 Citations
19 Claims
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1. A method for continuously and non-invasively monitoring blood pressure of a patient, the method comprising the steps of:
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positioning a first ultrasound sensor and a second ultrasound sensor aligned with a blood vessel of the patient, the first and second ultrasound sensors being operable to determine the diameter of the blood vessel and the flow rate of blood through the blood vessel; obtaining a first blood flow rate determined from the first ultrasound sensor, a second blood flow rate determined from the second ultrasound sensor, and a blood vessel radius; utilizing a transmission line model to represent the blood vessel, where the voltage at each node of the transmission line model corresponds to the blood pressure, the transmission line model including an input current source and an output current source positioned between an RLC ladder network, wherein the input current source is the first blood flow rate and the output current source is the second blood flow rate; developing a series of state variable equations based on the transmission line model; and inputting the obtained first blood flow rate, the second blood flow rate and the blood vessel radius into a Kalman filter; utilizing the Kalman filter to estimate the state variables of the transmission line model; using a transmission-line-based computation to estimate the blood pressure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for continuously and non-invasively monitoring blood pressure of a patient, the method comprising the steps of:
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positioning a first non-invasive ultrasound sensor aligned with a blood vessel of the patient, the first ultrasound sensor being operable to determine a first diameter of the blood vessel and a first flow rate through the blood vessel; positioning a second ultrasound sensor spaced a distance from the first ultrasound sensor and aligned with the same blood vessel of the patient, the second ultrasound sensor being operable to determine a second diameter of the blood vessel and a second flow rate of blood through the blood vessel; creating a transmission line model to represent the blood vessel, wherein the transmission line model includes an RLC ladder network extending between an input current source and an output current source, wherein the input current source corresponds to the first blood flow rate determined by the first ultrasound sensor and the output current source corresponds to the second blood flow rate determined by the second ultrasound sensor; and utilizing a transmission-line-based computation to estimate the voltage at each node of the transmission line model, wherein the voltage corresponds to the blood pressure of the patient. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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Specification