Continuous non-invasive blood pressure measurement apparatus and methods providing automatic recalibration
First Claim
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1. A method for maintaining calibration of a continuous non-invasive blood pressure (CNIBP) measurement system, the method comprising:
- performing, using one or more processors, a calibration by;
obtaining, for a subject, a reference blood pressure value, differential pulse transit time, and reference pulse wave data, the reference pulse wave data corresponding to one or more reference pulse waves; and
calculating and storing coefficients of a continuous non-invasive blood pressure calculation formula based, at least in part, on the reference blood pressure value and the differential pulse transit time;
obtaining, using one or more processors, subsequent pulse wave data characterizing one or more subsequent pulse waves of the subject and evaluating a recalibration condition based, at least in part, on a comparison of the subsequent pulse wave data to the reference pulse wave data, wherein the recalibration condition is based, at least in part, on at least one of a first feature, a second feature, and a third feature of the reference and subsequent pulse waves;
the first feature comprising a pulse wave area of the reference and subsequent pulse waves;
the second feature comprising a time difference, Δ
T, between two internal features within the reference and subsequent pulse waves; and
the third feature comprising a pulse wave shape of the reference and subsequent pulse waves; and
if the recalibration condition is satisfied, performing a new calibration.
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Abstract
A blood pressure measurement system is configured to perform a calibration automatically when a calibration condition is satisfied. The calibration condition is based upon one or more parameters of pulse waves of a subject. The parameters may include pulse wave area; a time difference between systolic peak and reflected wave peak or dichrotic notch in the pulse wave and a shape of at least a portion of the pulse wave.
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Citations
60 Claims
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1. A method for maintaining calibration of a continuous non-invasive blood pressure (CNIBP) measurement system, the method comprising:
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performing, using one or more processors, a calibration by; obtaining, for a subject, a reference blood pressure value, differential pulse transit time, and reference pulse wave data, the reference pulse wave data corresponding to one or more reference pulse waves; and calculating and storing coefficients of a continuous non-invasive blood pressure calculation formula based, at least in part, on the reference blood pressure value and the differential pulse transit time; obtaining, using one or more processors, subsequent pulse wave data characterizing one or more subsequent pulse waves of the subject and evaluating a recalibration condition based, at least in part, on a comparison of the subsequent pulse wave data to the reference pulse wave data, wherein the recalibration condition is based, at least in part, on at least one of a first feature, a second feature, and a third feature of the reference and subsequent pulse waves; the first feature comprising a pulse wave area of the reference and subsequent pulse waves; the second feature comprising a time difference, Δ
T, between two internal features within the reference and subsequent pulse waves; andthe third feature comprising a pulse wave shape of the reference and subsequent pulse waves; and if the recalibration condition is satisfied, performing a new calibration. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 52)
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40. A method for triggering recalibration of a continuous non-invasive blood pressure (CNIBP) measurement system, the method comprising:
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obtaining, using one or more processors, pulse wave data from a subject, the pulse wave data comprising a signal representing amplitude of pulse waves in the subject as a function of time; determining blood pressure based on a differential pulse transit time measured from the subject; and comparing, using one or more processors, at least one feature of the pulse wave data to a corresponding reference feature, the at least one feature comprising one or more of a first feature, a second feature, and a third feature of the pulse waves; the first feature comprising a time difference, Δ
T, between two internal features within the pulse waves;the second feature comprising a pulse wave shape of a portion of the pulse waves; and the third feature comprising an amplitude of the pulse waves and/or a width of the pulse waves.
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41. Apparatus for continuous non-invasive blood pressure (CNIBP) measurement, the apparatus comprising:
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a reference blood pressure measurement mechanism; a first CNIBP sensor having an output signal which varies with a blood pressure of a subject; a second CNIBP sensor having an output signal which varies with a blood pressure of the subject; and a CNIBP controller capable of computing a blood pressure of the subject from the output signal of the first and second CNIBP sensors according to a CNIBP calculation formula comprising a coefficient; wherein the CNIBP controller is capable of triggering the reference blood pressure measurement mechanism to obtain a reference blood pressure, and of using the reference blood pressure to determine a new value for the coefficient by; monitoring a pulse wave signal representing pulse waves of the subject; evaluating a recalibration condition comparing at least one feature of the pulse wave signal to a stored template, the at least one feature comprising one or more of a first feature, a second feature, and a third feature of the pulse waves; the first feature comprising a time difference, Δ
T, between two features within one of the pulse waves;the second feature comprising a pulse wave shape of a portion of the pulse waves; and the third feature comprising an amplitude of the pulse waves and/or a width of the pulse waves; and determining whether the recalibration condition is satisfied. - View Dependent Claims (42, 43, 44, 45, 46, 47, 48, 49, 50)
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51. Apparatus for triggering recalibration of a continuous non-invasive blood pressure (CNIBP) measurement system, the apparatus comprising:
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an input capable of receiving pulse wave data from a subject, the pulse wave data comprising a signal representing amplitude of pulse waves in the subject as a function of time; and a processor capable of executing software instructions which cause the processor to; determine blood pressure based on a differential pulse transit time measured from the subject; and compare at least one feature of the pulse wave data to a corresponding reference feature, the at least one feature comprising one or more of a first feature, a second feature, and a third feature of the pulse waves; the first feature comprising a time difference, Δ
T, between two internal features within the pulse waves;the second feature comprising a pulse wave shape of a portion of the pulse waves; and the third feature comprising an amplitude of the pulse waves and/or a width of the pulse waves.
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53. A system for continuous non-invasive blood pressure (CNIBP) measurement, the system comprising:
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a blood pressure measurement mechanism, capable of providing a reference blood pressure measurement of a subject; a first sensor capable of producing a first signal, based, at least in part, on a first pulse wave at a distance from a heart of said subject; a second sensor capable of producing a second signal, based, at least in part, on the first pulse wave, or a second pulse wave, at a second distance from said heart of said subject; a controller capable of generally continually computing blood pressure of said subject from said first and second signals, based, at least in part, on a formula comprising a coefficient; a calibration controller capable of determining the coefficient based, at least in part, on the reference blood pressure measurement; and a recalibration controller configured to activate the blood pressure measurement mechanism and/or the calibration controller, based, at least in part, on a first feature, a second feature, a third feature and/or a fourth feature of the first signal; the first feature comprising a pulse wave area of the first and/or second pulse waves; the second feature comprising a time difference, AT, between two internal features within the first and/or second pulse waves; the third feature comprising a pulse wave shape of at least a portion of the first and/or second pulse waves; and the fourth feature comprising an amplitude and/or width of the first and/or second pulse waves. - View Dependent Claims (54, 55, 56, 57, 58, 59, 60)
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Specification