Method and apparatus for ultrasonic continuous, non-invasive blood pressure monitoring

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:

• (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, wherein estimating the velocity further comprises correcting for pulse wave reflections that travel up the artery;
• 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.

A method for estimating pulse wave velocity in an artery, comprising the following steps:

• (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.

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:

• (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.

A system for autonomous monitoring of blood pressure in an artery of a patient comprising:

• 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, wherein means for estimating the velocity further comprises means for correcting for reflections of the pulse wave that travel up the artery;
• 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.

A method for autonomously locating an M-mode line through the center of an artery, comprising the following steps:

• (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.