Method and apparatus for ultrasonic continuous, non-invasive blood pressure monitoring
First Claim
1. A method for monitoring of blood pressure in an artery of a patient, comprising the following steps:
- (a) transmitting beams of ultrasonic wave energy that intersect the artery;
(b) acquiring acoustic data by transducing ultrasound wave energy, transmitted and returned from the artery wall, the blood flowing through the artery and the tissue surrounding the artery, into electrical signals;
(c) estimating the diameter of the artery based on a first set of the acquired acoustic data;
(d) calculating the arterial lumen area based on the estimated arterial diameter;
(e) estimating the velocity of a pulse wave traveling down the artery based on a second set of the acquired acoustic data; and
(f) computing the blood pressure as a function of the estimated lumen area, the estimated pulse wave velocity and respective reference values for blood pressure and lumen area.
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Abstract
Ultrasound is used to provide input data for a blood pressure estimation scheme. The use of transcutaneous ultrasound provides arterial lumen area and pulse wave velocity information. In addition, ultrasound measurements are taken in such a way that all the data describes a single, uniform arterial segment. Therefore a computed area relates only to the arterial blood volume present. Also, the measured pulse wave velocity is directly related to the mechanical properties of the segment of elastic tube (artery) for which the blood volume is being measured. In a patient monitoring application, the operator of the ultrasound device is eliminated through the use of software that automatically locates the artery in the ultrasound data, e.g., using known edge detection techniques. Autonomous operation of the ultrasound system allows it to report blood pressure and blood flow traces to the clinical users without those users having to interpret an ultrasound image or operate an ultrasound imaging device.
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Citations
49 Claims
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1. A method for monitoring of blood pressure in an artery of a patient, comprising the following steps:
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(a) transmitting beams of ultrasonic wave energy that intersect the artery;
(b) acquiring acoustic data by transducing ultrasound wave energy, transmitted and returned from the artery wall, the blood flowing through the artery and the tissue surrounding the artery, into electrical signals;
(c) estimating the diameter of the artery based on a first set of the acquired acoustic data;
(d) calculating the arterial lumen area based on the estimated arterial diameter;
(e) estimating the velocity of a pulse wave traveling down the artery based on a second set of the acquired acoustic data; and
(f) computing the blood pressure as a function of the estimated lumen area, the estimated pulse wave velocity and respective reference values for blood pressure and lumen area. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A system for autonomous monitoring of blood pressure in an artery of a patient, comprising an array of ultrasonic transducer elements, data processing means, and means for delivering signals derived from the output of said array to said data processing means, wherein said data processing means are programmed to perform the following steps:
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(a) controlling said array to transmit beams of ultrasonic wave energy;
(b) beamforming acoustic data output from said array in response to impinging ultrasound wave energy transmitted and returned from the artery wall, the blood flowing through the artery and the tissue surrounding the artery;
(c) estimating the diameter of the artery based on a first set of the acoustic data;
(d) calculating the arterial lumen area based on the estimated arterial diameter;
(e) estimating the velocity of a pulse wave traveling down the artery based on a second set of the acoustic data; and
(f) computing the blood pressure as a function of the estimated lumen area, the estimated pulse wave velocity and respective reference values for blood pressure and lumen area. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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38. A method for estimating pulse wave velocity in an artery, comprising the following steps:
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(a) transmitting beams of ultrasonic wave energy that intersect the artery at first and second locations separated by a distance along the axis of the artery;
(b) acquiring acoustic data by transducing ultrasound wave energy, transmitted and returned from the artery wall, the blood flowing through the artery and the tissue surrounding the artery, into electrical signals; and
(c) estimating the velocity of a pulse wave traveling down the artery based at least partly on the acoustic data acquired at said first and second axial locations using an algorithm that corrects for pulse wave reflections. - View Dependent Claims (39, 40, 41, 42)
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43. A system for estimating pulse wave velocity in an artery, comprising an array of ultrasonic transducer elements, data processing means, and means for delivering signals derived from the output of said array to said data processing means, wherein said data processing means are programmed to perform the following steps:
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(a) controlling said array to transmit beams of ultrasonic wave energy that intersect the artery at first and second locations separated by a distance along the axis of the artery;
(b) beamforming acoustic data output from said array in response to impinging ultrasound wave energy transmitted and returned from the artery wall, the blood flowing through the artery and the tissue surrounding the artery; and
(c) estimating the velocity of a pulse wave traveling down the artery based at least partly on the acoustic data acquired at said first and second locations using an algorithm that corrects for pulse wave reflections. - View Dependent Claims (44, 45, 46, 47)
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48. A system for autonomous monitoring of blood pressure in an artery of a patient comprising:
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means for transmitting beams of ultrasonic wave energy that intersect the artery;
means for acquiring acoustic data by transducing ultrasound wave energy, transmitted and returned from the artery wall, the blood flowing through the artery and the tissue surrounding the artery, into electrical signals;
means for estimating the diameter of the artery based on a first set of the acquired acoustic data;
means for calculating the arterial lumen area based on the estimated arterial diameter;
means for estimating the velocity of a pulse wave traveling down the artery based on a second set of the acquired acoustic data; and
means for computing the blood pressure as a function of the estimated lumen area, the estimated pulse wave velocity and respective reference values for blood pressure and lumen area.
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49. A method for autonomously locating an M-mode line through the center of an artery, comprising the following steps:
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(a) acquiring first and second B-mode images in first and second planes that pass through the artery at first and second axial locations respectively;
(b) calculating the location of the center of the artery in each of said first and second planes based on data acquired in step (a);
(c) determining the location of the center of the artery in a third plane located between said first and second plane by interpolating the calculated artery center location data for said first and second B-mode images; and
(d) adjusting the beamsteering angle of an M-mode line so that the M-mode line passes through the artery center in said third plane.
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Specification