Method and apparatus for the noninvasive determination of arterial blood pressure

A method of measuring blood pressure, comprising:

• positioning a first transducer capable of producing a first signal related to the pressure applied thereto, in proximity to the blood vessel of a subject;
• urging said first transducer against the tissue of said subject, said first transducer at least partly compressing said blood vessel in response to said urging;
• positioning a second transducer capable or transmitting and receiving acoustic energy in proximity to said blood vessel;
• transmitting an acoustic wave into said blood vessel using said second transducer;
• receiving at least one echo from said blood vessel using said second transducer, said second transducer generating a second signal related to said echo;
• measuring the frequency of said echo based on said second signal;
• forming a time-frequency distribution based on said frequency;
• and
• measuring the pressure within said blood vessel using said first transducer when said time-frequency distribution is maximized.

A method of measuring blood pressure within a blood vessel of a subject, comprising:

• progressively varying the compression of at least a portion of said blood vessel;
• transmitting acoustic energy into said blood vessel during at least a portion of said act of varying the compression;
• receiving echoes of said acoustic energy from said blood vessel during at least a portion of said act of varying the compression;
• forming a time-frequency representation of said echoes;
• and
• determining the pressure within said blood vessel when said representation satisfies a given condition.

A method of measuring blood pressure within a blood vessel of a subject, comprising the steps of:

• progressively varying the compression of at least a portion of said blood vessel to alter the hemodynamic properties thereof;
• transmitting acoustic energy into said blood vessel during at least a portion of said act of varying the compression to generate echoes form said vessel and blood contained therein;
• receiving said echoes of said acoustic energy from said blood vessel during at least a portion of said act of varying the compression;
• forming a time-frequency representation of said echoes to identify at least one predetermined condition therein;
• and
• determining when said representation satisfies said predetermined condition to determine the pressure within said blood vessel non-invasively.

A method of measuring blood pressure within the radial artery of a living subject, comprising:

• varying the level of compression of at least a portion of said artery;
• transmitting ultrasonic energy into said artery during at least a portion of said act of varying the compression;
• receiving echoes of said acoustic energy from said artery during at least a portion of said act of varying the compression;
• determining blood velocity based at least in part on said echoes;
• forming a time-frequency distribution of said echoes based at least in part on said blood velocity;
• selecting an interval within which said distribution is evaluated;
• determining the mean of said distribution within said interval;
• and
• determining the pressure within said artery when said mean of said distribution satisfies a given condition.

A blood pressure monitoring device, comprising:

• first apparatus adapted to compress a blood vessel of a subject and measure the pressure applied thereto;
• second apparatus adapted to transmit acoustic energy into said blood vessel and receive at least one echo resulting therefrom;
• and
• a processor operatively coupled to said first and second apparatus and configured to process said measured pressure and said at least one echo;
• wherein said device is further configured to:
• (i) progressively vary the compression of at least a portion of said blood vessel;
• (ii) transmit said acoustic energy into said blood vessel and receive said at least one echo therefrom during at least a portion of said act of varying the compression;
• (iii) form a time-frequency representation of said at least one echo using at least said processor;
• and
• (iv) determine the pressure within said blood vessel when said representation satisfies a given condition.