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; and
a processing unit in communication with the voltage sensing electrodes, wherein the processing unit is configured to use a voltage sensed by the voltage sensing electrodes to calculate a cardiogenically induced impedance variation value of the patient, and to determine a stroke volume of the patient by multiplying the cardiogenically induced impedance variation value by a volume conductor VC and by a left ventricular ejection time TLVE;
wherein the processing unit determines the volume conductor VC as;
where;
C1 is at least 1.0 and no greater than 8.0,Z0 is a transthoracic base impedance or a static D.C. component of a total transthoracic impedance,Zc is a critical level of base impedance that is at least 15Ω and
no greater than 25Ω
,C2 is at least 0.10 and no greater than 0.75,W is a kilogram weight of the patient, andC3 is at least 35 and no greater than 100.
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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 voltage sensed by the voltage sensing electrodes to calculate a cardiogenically induced impedance variation value of the patient, and to determine a stroke volume of the patient by multiplying the cardiogenically induced impedance variation value by a volume conductor VC and by a left ventricular ejection time TLVE.
78 Citations
28 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; and a processing unit in communication with the voltage sensing electrodes, wherein the processing unit is configured to use a voltage sensed by the voltage sensing electrodes to calculate a cardiogenically induced impedance variation value of the patient, and to determine a stroke volume of the patient by multiplying the cardiogenically induced impedance variation value by a volume conductor VC and by a left ventricular ejection time TLVE; wherein the processing unit determines the volume conductor VC as; where; C1 is at least 1.0 and no greater than 8.0, Z0 is a transthoracic base impedance or a static D.C. component of a total transthoracic impedance, Zc is a critical level of base impedance that is at least 15Ω and
no greater than 25Ω
,C2 is at least 0.10 and no greater than 0.75, W is a kilogram weight of the patient, and C3 is at least 35 and no greater than 100. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
is greater than 1.0, and for all values of Z0 at least 20Ω
, the processing unit determines that1.0.
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9. The apparatus of claim 1, wherein C2 multiplied by C3 is at least 10 and no greater than 35.
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10. The apparatus of claim 9, wherein C2 multiplied by C3 is substantially 17.5 mL/kg.
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11. The apparatus of claim 1, wherein:
wherein; C4 is at least 35 and no greater than 100, BMIN is a normalized body mass index that is at least 0.5 and no greater than 5.0, and y is at least 0.25 and no greater than 1.0.
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12. The apparatus of claim 11, wherein:
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C4 is substantially 70 mL/kg, BMIN is substantially 1.0, and y is substantially 0.5.
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13. The apparatus of claim 12, wherein:
wherein; H is the patient'"'"'s height in meters, and C5 is the patient'"'"'s ideal body mass index (kg/m2) of at least 10 and no greater than 100.
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14. The apparatus of claim 13, wherein C5 is substantially 24 kg/m2.
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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 cardiogenically induced impedance variation value of the patient using the measured voltage (U(t)); determining a volume conductor VC as; where; C1 is at least 1.0 and no greater than 8.0, Z0 is a transthoracic base impedance or a static D.C. component of a total transthoracic impedance, Zc is a critical level of base impedance that is at least 15Ω and
no greater than 25Ω
,C2 is at least 0.10 and no greater than 0.75, W is a kilogram weight of the patient, and C3 is at least 35 and no greater than 100; and calculating a stroke volume of the patient by multiplying the cardiogenically induced impedance variation value by the volume conductor VC and by a left ventricular ejection time TLVE. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
is greater than 1.0, and for all values of Z0 at least 20Ω
, determining thatis 1.0.
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23. The method of claim 15, further comprising:
determining C2 multiplied by C3 is at least 10 and no greater than 35.
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24. The method of claim 23, wherein C2 multiplied by C3 is substantially 17.5 mL/kg.
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25. The method of claim 15, further comprising:
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determining that wherein; C4 is at least 35 and no greater than 100, BMIN is a normalized body mass index that is at least 0.5 and no greater than 5.0, and y is at least 0.25 and no greater than 1.0.
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26. The method of claim 25, wherein:
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C4 is substantially 70 mL/kg, BMIN is substantially 1.0, and y is substantially 0.5.
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27. The method of claim 26, wherein:
wherein; H is the patient'"'"'s height in meters, and C5 is the patient'"'"'s ideal body mass index (kg/m2) of at least 10 and no greater than 100.
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28. The method of claim 27, wherein C5 is substantially 24 kg/m2.
Specification