Method and apparatus for the noninvasive determination of arterial blood pressure
First Claim
1. A method of continuously and non-invasively estimating the blood pressure existing within the artery of a subject, comprising:
- estimating the diastolic pressure within said artery;
estimating the mean pressure within said artery;
sensing a pressure waveform from said artery;
deriving a scaling factor by modeling a mechanical impulse response of said artery as a mathematical function based at least in part on said estimated diastolic pressure and said estimated mean pressure; and
continuously estimating the blood pressure within said artery based on said scaling factor, said sensed pressure waveform, and said mean pressure.
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Abstract
A method and apparatus for determining the mean arterial blood pressure (MAP) of a subject during tonometric conditions. In one embodiment, the apparatus comprises one or more pressure and ultrasound transducers placed over the radial artery of a human subject'"'"'s wrist, the latter transmitting and receiving acoustic energy so as to permit the measurement of blood velocity during periods of variable compression of the artery. During compression, the ultrasound velocity waveforms are recorded and processed using time-frequency analysis. The time at which the mean time-frequency distribution is maximal corresponds to the time at which the transmural pressure equals zero, and the mean pressure read by the transducer equals the mean pressure within the artery. In another aspect of the invention, the ultrasound transducer is used to position the transducer over the artery such that the accuracy of the measurement is maximized. In yet another aspect of the invention, a wrist brace useful for measuring blood pressure using the aforementioned apparatus is disclosed. A method of continuously estimating systolic and diastolic pressure is also described.
223 Citations
15 Claims
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1. A method of continuously and non-invasively estimating the blood pressure existing within the artery of a subject, comprising:
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estimating the diastolic pressure within said artery;
estimating the mean pressure within said artery;
sensing a pressure waveform from said artery;
deriving a scaling factor by modeling a mechanical impulse response of said artery as a mathematical function based at least in part on said estimated diastolic pressure and said estimated mean pressure; and
continuously estimating the blood pressure within said artery based on said scaling factor, said sensed pressure waveform, and said mean pressure. - View Dependent Claims (2, 3)
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4. A method of continuously and non-invasively estimating the blood pressure existing within the artery of a subject, comprising:
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estimating the diastolic pressure within said artery;
estimating the mean pressure within said artery by;
(i) transmitting an acoustic signal into said artery;
(ii) receiving an echo from said acoustic signal;
(iii) analyzing said echo to estimate the velocity of said blood flowing in said artery;
(iv) forming a time-frequency representation of said velocity; and
(v) generating an estimate of mean blood pressure when said time-frequency representation satisfies a given condition;
sensing a pressure waveform from said artery;
deriving a scaling factor based at least in part on said estimated diastolic pressure and said estimated mean pressure; and
continuously estimating the blood pressure within said artery based on said scaling factor, said sensed pressure waveform, and said mean pressure. - View Dependent Claims (5)
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6. A method of continuously and non-invasively estimating the blood pressure existing within the artery of a subject, comprising:
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estimating a first pressure within said artery;
estimating a second pressure within said artery;
sensing a pressure waveform from said artery;
deriving a scaling factor by modeling a mechanical impulse response of said artery as a linear autoregression function based at least in part on said estimated first and second pressures; and
continuously estimating the blood pressure within said artery based on said scaling factor, said sensed pressure waveform, and said second pressure. - View Dependent Claims (7)
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8. A method of continuously and non-invasively estimating the blood pressure existing within the artery of a subject, comprising:
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estimating a first pressure within said artery;
estimating a second pressure within said artery, comprising;
transmitting an acoustic signal into and receiving an echo from said artery;
analyzing said echo to estimate the velocity of said blood flowing in said artery;
forming a time-frequency representation of said velocity; and
generating an estimate of said second pressure when said time-frequency representation satisfies a given condition;
sensing a pressure waveform from said artery;
deriving a scaling factor based at least in part on said estimated first and second pressures; and
continuously estimating the blood pressure within said artery based on said scaling factor, said sensed pressure waveform, and at least one of said first and second pressures. - View Dependent Claims (9)
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10. Apparatus for continuously and non-invasively estimating the blood pressure existing within the artery of a subject, comprising:
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a sensor adapted to detect a pressure waveform from said artery and generate electrical signals relating thereto;
a processor operatively coupled to said sensor and adapted to process said electrical signals, said processing of said signals comprising at least;
(i) estimating a first pressure within said artery;
(ii) estimating a second pressure within said artery;
(iii) deriving a scaling factor by modeling a mechanical impulse response of said artery as a function based at least in part on said estimated first and second pressures; and
(iv) continuously estimating the blood pressure within said artery based on said scaling factor, said pressure waveform, and at least one of said first and second pressures. - View Dependent Claims (11)
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12. Apparatus with means for continuously and non-invasively estimating the blood pressure existing within the artery of a subject, comprising:
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means for detecting a pressure waveform from said artery, including means for generating electrical signals relating thereto;
processor means operatively coupled to said means for detecting for processing said electrical signals, said processing of said signals comprising at least;
(i) estimating a first pressure within said artery;
(ii) estimating a second pressure within said artery;
(iii) deriving a scaling factor by modeling a mechanical impulse response of said artery as a mathematical function based at least in part on said estimated first and second pressures; and
(iv) continuously estimating the blood pressure within said artery based on said scaling factor, said pressure waveform, and at least one of said first and second pressures. - View Dependent Claims (13)
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14. A method of continuously and non-invasively estimating the blood pressure existing within the artery of a subject, comprising the steps of:
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estimating a first pressure within said artery;
estimating a second pressure within said artery;
sensing a pressure waveform from said artery;
modeling a mechanical impulse response of said artery as a mathematical function based at least in part on said estimated first and second pressures to derive a scaling factor; and
using said scaling factor, said sensed pressure waveform, and said second pressure to estimate continuously the blood pressure within said artery. - View Dependent Claims (15)
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Specification