Apparatus and method for determination of stroke volume using the brachial artery
First Claim
1. An apparatus for determining stroke volume by bioimpedance from a patient, comprising:
- two or more spaced apart alternating current flow electrodes positionable on a patient;
two or more spaced apart voltage sensing electrodes positionable on the patient and between the alternating current flow electrodes;
an alternating current source electrically connected to the alternating current flow electrodes;
a voltmeter electrically connected to the voltage sensing electrodes;
a processing unit in communication with the voltage sensing electrodes, wherein the processing unit is capable of using a voltage sensed by the voltage sensing electrodes to calculate a mean value of a second time-derivative of a cardiogenically induced impedance variation of the patient and to determine therefrom a stroke volume of the patient;
wherein the processing unit calculates the mean value of the second time-derivative of the cardiogenically induced impedance variation as a peak rate of change of the cardiogenically induced impedance variation divided by a time to peak value of the cardiogenically induced impedance; and
wherein the time to peak value is a selected time value at least as great as 0.01 seconds and no greater than 0.1 seconds.
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Accused Products
Abstract
Provided herein are methods and apparatus for stroke volume determination by bioimpedance from a patient'"'"'s upper arm, or brachium, or a patient'"'"'s thorax, utilizing pulsations of the arteries contained therein. The apparatus includes two or more spaced apart alternating current flow electrodes positioned on the patient'"'"'s arm or thorax and two or more spaced apart voltage sensing electrodes positioned on the patient'"'"'s arm or thorax and in-between alternating current flow electrodes. The system and method utilizes the mean value of the second time-derivative of the cardiogenically induced impedance variation of the patient using the measured voltage from the voltage sensors in calculating the stroke volume of the patient.
87 Citations
26 Claims
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1. An apparatus for determining stroke volume by bioimpedance from a patient, comprising:
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two or more spaced apart alternating current flow electrodes positionable on a patient; two or more spaced apart voltage sensing electrodes positionable on the patient and between the alternating current flow electrodes; an alternating current source electrically connected to the alternating current flow electrodes; a voltmeter electrically connected to the voltage sensing electrodes; a processing unit in communication with the voltage sensing electrodes, wherein the processing unit is capable of using a voltage sensed by the voltage sensing electrodes to calculate a mean value of a second time-derivative of a cardiogenically induced impedance variation of the patient and to determine therefrom a stroke volume of the patient; wherein the processing unit calculates the mean value of the second time-derivative of the cardiogenically induced impedance variation as a peak rate of change of the cardiogenically induced impedance variation divided by a time to peak value of the cardiogenically induced impedance; and wherein the time to peak value is a selected time value at least as great as 0.01 seconds and no greater than 0.1 seconds.
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2. An apparatus for determining stroke volume by bioimpedance from a patient, comprising:
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two or more spaced apart alternating current flow electrodes positionable on a patient; two or more spaced apart voltage sensing electrodes positionable on the patient and between the alternating current flow electrodes; an alternating current source electrically connected to the alternating current flow electrodes; a voltmeter electrically connected to the voltage sensing electrodes; a processing unit in communication with the voltage sensing electrodes, wherein the processing unit is capable of using a voltage sensed by the voltage sensing electrodes to calculate a mean value of a second time-derivative of a cardiogenically induced impedance variation of the patient and to determine therefrom a stroke volume of the patient; wherein the processing unit calculates the mean value of the second time-derivative of the cardiogenically induced impedance variation as a peak rate of change of the cardiogenically induced impedance variation divided by a time to peak value of the cardiogenically induced impedance; and wherein the time to peak value is a corrected rise time between an aortic valve of the patient opening and a peak rate of change of the cardiogenically induced impedance variation.
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3. An apparatus for determining stroke volume by bioimpedance from a patient, comprising:
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two or more spaced apart alternating current flow electrodes positionable on a patient; two or more spaced apart voltage sensing electrodes positionable on the patient and between the alternating current flow electrodes; an alternating current source electrically connected to the alternating current flow electrodes; a voltmeter electrically connected to the voltage sensing electrodes; a processing unit in communication with the voltage sensing electrodes, wherein the processing unit is capable of using a voltage sensed by the voltage sensing electrodes to calculate a mean value of a second time-derivative of a cardiogenically induced impedance variation of the patient and to determine therefrom a stroke volume of the patient; wherein the processing unit calculates the mean value of the second time-derivative of the cardiogenically induced impedance variation as a peak rate of change of the cardiogenically induced impedance variation divided by a time to peak value of the cardiogenically induced impedance; and wherein the time to peak value is calculated as (TTPc+TTPm)/A, where TTPm is a measured time period between an aortic valve of the patient opening and a peak rate of change of the cardiogenically induced impedance variation, TTPc is a corrected rise time between an aortic valve of the patient opening and a peak rate of change of the cardiogenically induced impedance variation, and A is a value greater than zero but not greater than 5.
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4. An apparatus for determining stroke volume by bioimpedance from a patient, comprising:
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two or more spaced apart alternating current flow electrodes positionable on a patient; two or more spaced apart voltage sensing electrodes positionable on the patient and between the alternating current flow electrodes; an alternating current source electrically connected to the alternating current flow electrodes; a voltmeter electrically connected to the voltage sensing electrodes; a processing unit in communication with the voltage sensing electrodes, wherein the processing unit is capable of using a voltage sensed by the voltage sensing electrodes to calculate a mean value of a second time-derivative of a cardiogenically induced impedance variation of the patient and to determine therefrom a stroke volume of the patient; wherein the processing unit calculates the mean value of the second time-derivative of the cardiogenically induced impedance variation as a peak rate of change of the cardiogenically induced impedance variation divided by a time to peak value of the cardiogenically induced impedance; and wherein the time to peak value is calculated as (TTPc+TTPb)/A, where TTPb is a selected time value at least as great as 0.01 seconds and no greater than 0.1 seconds, and TTPc is a corrected rise time between an aortic valve of the patient opening and a peak rate of change of the cardiogenically induced impedance variation, and A is a value greater than zero but not greater than 5.
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5. An apparatus for determining stroke volume by bioimpedance from a patient, comprising:
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two or more spaced apart alternating current flow electrodes positionable on a patient; two or more spaced apart voltage sensing electrodes positionable on the patient and between the alternating current flow electrodes; an alternating current source electrically connected to the alternating current flow electrodes; a voltmeter electrically connected to the voltage sensing electrodes; a processing unit in communication with the voltage sensing electrodes, wherein the processing unit is capable of using a voltage sensed by the voltage sensing electrodes to calculate a mean value of a second time-derivative of a cardiogenically induced impedance variation of the patient and to determine therefrom a stroke volume of the patient; wherein the processing unit calculates the mean value of the second time-derivative of the cardiogenically induced impedance variation as a peak rate of change of the cardiogenically induced impedance variation divided by a time to peak value of the cardiogenically induced impedance; and wherein the time to peak value is calculated as (TTPm+TTPb)/A, where TTPb is a selected time value at least as great as 0.01 seconds and no greater than 0.1 seconds, and TTPm is a measured time period between an aortic valve of the patient opening and a peak rate of change of the cardiogenically induced impedance variation, and A is a value greater than zero but not greater than 5.
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6. An apparatus for determining stroke volume by bioimpedance from a patient, comprising:
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two or more spaced apart alternating current flow electrodes positionable on a patient; two or more spaced apart voltage sensing electrodes positionable on the patient and between the alternating current flow electrodes; an alternating current source electrically connected to the alternating current flow electrodes; a voltmeter electrically connected to the voltage sensing electrodes; a processing unit in communication with the voltage sensing electrodes, wherein the processing unit is capable of using a voltage sensed by the voltage sensing electrodes to calculate a mean value of a second time-derivative of a cardiogenically induced impedance variation of the patient and to determine therefrom a stroke volume of the patient; wherein the processing unit uses the equation; - View Dependent Claims (7, 8, 9, 10, 11, 12, 13)
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14. A method of determining stroke volume by bioimpedance from a patient, comprising:
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positioning two or more spaced apart alternating current flow electrodes on a patient; positioning two or more spaced apart voltage sensing electrodes on the patient and between the alternating current flow electrodes; providing an alternating current flow (I(t)) through the electrically conductive electrodes creating a current field; measuring a voltage (U(t)) between the voltage sensing electrodes within the current field; calculating a mean value of a second time-derivative of a cardiogenically induced impedance variation of the patient using the measured voltage (U(t)); calculating the stroke volume (SV) of the patient using the calculated second time-derivative mean value; wherein the calculating of the second time-derivative mean value includes dividing a peak rate of change of the cardiogenically induced impedance variation by a time to peak value of the cardiogenically induced impedance peak rate of change; and wherein the time to peak value is determined by selecting a time value at least as great as 0.01 seconds and no greater than 0.1 seconds.
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15. A method of determining stroke volume by bioimpedance from a patient, comprising:
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positioning two or more spaced apart alternating current flow electrodes on a patient; positioning two or more spaced apart voltage sensing electrodes on the patient and between the alternating current flow electrodes; providing an alternating current flow (I(t)) through the electrically conductive electrodes creating a current field; measuring a voltage (U(t)) between the voltage sensing electrodes within the current field; calculating a mean value of a second time-derivative of a cardiogenically induced impedance variation of the patient using the measured voltage (U(t)); calculating the stroke volume (SV) of the patient using the calculated second time-derivative mean value; wherein the calculating of the second time-derivative mean value includes dividing a peak rate of change of the cardiogenically induced impedance variation by a time to peak value of the cardiogenically induced impedance peak rate of change; and wherein the time to peak value is determined by correcting a rise time between an aortic valve of the patient opening and a peak rate of change of the cardiogenically induced impedance variation.
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16. A method of determining stroke volume by bioimpedance from a patient, comprising:
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positioning two or more spaced apart alternating current flow electrodes on a patient; positioning two or more spaced apart voltage sensing electrodes on the patient and between the alternating current flow electrodes; providing an alternating current flow (I(t)) through the electrically conductive electrodes creating a current field; measuring a voltage (U(t)) between the voltage sensing electrodes within the current field; calculating a mean value of a second time-derivative of a cardiogenically induced impedance variation of the patient using the measured voltage (U(t)); calculating the stroke volume (SV) of the patient using the calculated second time-derivative mean value; wherein the calculating of the second time-derivative mean value includes dividing a peak rate of change of the cardiogenically induced impedance variation by a time to peak value of the cardiogenically induced impedance peak rate of change; and wherein the time to peak value is determined by calculating (TTPc+TTPm)/A, where TTPm is a measured time period between an aortic valve of the patient opening and a peak rate of change of the cardiogenically induced impedance variation, TTPc is a corrected rise time between an aortic valve of the patient opening and a peak rate of change of the cardiogenically induced impedance variation, and A is a value greater than zero but not greater than 5.
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17. A method of determining stroke volume by bioimpedance from a patient, comprising:
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positioning two or more spaced apart alternating current flow electrodes on a patient; positioning two or more spaced apart voltage sensing electrodes on the patient and between the alternating current flow electrodes; providing an alternating current flow (I(t)) through the electrically conductive electrodes creating a current field; measuring a voltage (U(t)) between the voltage sensing electrodes within the current field; calculating a mean value of a second time-derivative of a cardiogenically induced impedance variation of the patient using the measured voltage (U(t)); calculating the stroke volume (SV) of the patient using the calculated second time-derivative mean value; wherein the calculating of the second time-derivative mean value includes dividing a peak rate of change of the cardiogenically induced impedance variation by a time to peak value of the cardiogenically induced impedance peak rate of change; and wherein the time to peak value is determined by calculating (TTPc+TTPb)/A, where TTPb is a selected time value at least as great as 0.01 seconds and no greater than 0.1 seconds, and TTPc is a corrected rise time between an aortic valve of the patient opening and a peak rate of change of the cardiogenically induced impedance variation, and A is a value greater than zero but not greater than 5.
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18. A method of determining stroke volume by bioimpedance from a patient, comprising:
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positioning two or more spaced apart alternating current flow electrodes on a patient; positioning two or more spaced apart voltage sensing electrodes on the patient and between the alternating current flow electrodes; providing an alternating current flow (I(t)) through the electrically conductive electrodes creating a current field; measuring a voltage (U(t)) between the voltage sensing electrodes within the current field; calculating a mean value of a second time-derivative of a cardiogenically induced impedance variation of the patient using the measured voltage (U(t)); calculating the stroke volume (SV) of the patient using the calculated second time-derivative mean value; wherein the calculating of the second time-derivative mean value includes dividing a peak rate of change of the cardiogenically induced impedance variation by a time to peak value of the cardiogenically induced impedance peak rate of change; and wherein the time to peak value is determined by calculating (TTPm+TTPb)/A, where TTPb is a selected time value at least as great as 0.01 seconds and no greater than 0.1 seconds, and TTPm is a measured time period between an aortic valve of the patient opening and a peak rate of change of the cardiogenically induced impedance variation, and A is a value greater than zero but not greater than 5.
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19. A method of determining stroke volume by bioimpedance from a patient, comprising:
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positioning two or more spaced apart alternating current flow electrodes on a patient; positioning two or more spaced apart voltage sensing electrodes on the patient and between the alternating current flow electrodes; providing an alternating current flow (I(t)) through the electrically conductive electrodes creating a current field; measuring a voltage (U(t)) between the voltage sensing electrodes within the current field; calculating a mean value of a second time-derivative of a cardiogenically induced impedance variation of the patient using the measured voltage (U(t)); and calculating the stroke volume (SV) of the patient using the calculated second time-derivative mean value; wherein the calculating of the stroke volume (SV) includes; determining a volume of electrically participating tissue Vc of the patient; determining a quasi-static base impedance Z0; determining a left ventricular ejection time TLVE of the patient; and calculating the stroke volume (SV) of the patient using the equation; - View Dependent Claims (20, 21, 22, 23, 24, 25, 26)
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Specification