Apparatus and methods of bioelectrical impedance analysis of blood flow
First Claim
1. Apparatus for computing a metric corresponding to a patient'"'"'s cardiac output, the apparatus comprising:
- a bioelectrical impedance recorder;
an endotracheal tube having a proximal portion, a distal portion, and a longitudinal axis, the endotracheal tube is adapted to be inserted in the trachea of the patient through one of the mouth, a nasal passageway, or a tracheotomy port;
first and second sense electrodes disposed on the distal portion and electrically coupled to the bioelectrical impedance recorder, the first and second sense electrodes spaced apart a first distance along the longitudinal axis;
means for urging the first and second sense electrodes against an interior wall of the patient'"'"'s airway;
first and second current electrodes electrically coupled to the bioelectrical impedance recorder for injecting a current into the patient'"'"'s thorax, the first and second current electrodes spaced apart a second distance greater than the first distance,wherein the first and second sense electrodes generate a signal corresponding to the bioelectrical impedance of blood flow through the aorta and the signal is provided to the bioelectrical impedance recorder.
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Abstract
Apparatus and methods are provided for monitoring cardiac output using bioelectrical impedance techniques in which first and second electrodes are placed in the trachea and/or bronchus in the vicinity of the ascending aorta, while an excitation current is injected into the thorax via first and second current electrodes, so that bioelectrical impedance measurements based on the voltage drop sensed by the first and second electrodes reflect voltage changes induced primarily by blood flow dynamics, rather than respiratory or non-cardiac related physiological effects. Additional sense electrodes may be provided, either internally, or externally, for which bioelectrical impedance values may be obtained. Methods are provided for computing cardiac output from bioelectrical impedance values. Apparatus and methods are also provided so that the measured cardiac output may be used to control administration of intravenous fluids to an organism or to optimize a heart rate controlled by a pacemaker.
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Citations
38 Claims
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1. Apparatus for computing a metric corresponding to a patient'"'"'s cardiac output, the apparatus comprising:
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a bioelectrical impedance recorder; an endotracheal tube having a proximal portion, a distal portion, and a longitudinal axis, the endotracheal tube is adapted to be inserted in the trachea of the patient through one of the mouth, a nasal passageway, or a tracheotomy port; first and second sense electrodes disposed on the distal portion and electrically coupled to the bioelectrical impedance recorder, the first and second sense electrodes spaced apart a first distance along the longitudinal axis; means for urging the first and second sense electrodes against an interior wall of the patient'"'"'s airway; first and second current electrodes electrically coupled to the bioelectrical impedance recorder for injecting a current into the patient'"'"'s thorax, the first and second current electrodes spaced apart a second distance greater than the first distance, wherein the first and second sense electrodes generate a signal corresponding to the bioelectrical impedance of blood flow through the aorta and the signal is provided to the bioelectrical impedance recorder. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method of measuring the cardiac output of an organism comprising steps of:
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providing a bioelectrical impedance recorder; providing an endotracheal tube having first and second sense electrodes disposed thereon, the first and second sense electrodes spaced apart a first distance; inserting the endotracheal tube in the trachea of the organism through a nasal passageway, the mouth of the organism, or a tracheotomy port to position first and second sense electrodes within an airway of the organism in the vicinity of the ascending aorta; coupling first and second current electrodes to inject a current into the thorax of the organism, the first and second current electrodes spaced apart a second distance greater than the first distance; applying a voltage from the bioelectrical impedance recorder between the first and second current electrodes so that a current flows through the tissues of the organism disposed along the second distance between the first and second current electrodes; and detecting with the bioelectrical impedance recorder a voltage developed across the first and second sense electrodes caused by the current flowing in the tissues of the organism, the voltage varying in accordance with changes in the bioelectrical impedance of the tissues. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24)
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25. Apparatus for computing a metric corresponding to a patient'"'"'s cardiac output, the apparatus comprising:
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a bioelectrical impedance recorder, an endotracheal tube having a proximal portion, a distal portion, and a longitudinal axis; first and second sense electrodes disposed on the distal portion and electrically coupled to the bioelectrical impedance recorder, the first and second sense electrodes spaced apart a first distance along the longitudinal axis; means for urging the first and second sense electrodes against an interior wall of the patient'"'"'s airway; first and second current electrodes electrically coupled to the bioelectrical impedance recorder for injecting a current into the patient'"'"'s thorax, the first and second current electrodes spaced apart a second distance greater than the first distance, at least one of the first or second current electrodes disposed on the endotracheal tube, wherein the first and second sense electrodes generate a signal corresponding to the bioelectrical impedance of blood flow through the aorta and the signal is provided to the bioelectrical impedance recorder. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32)
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33. Apparatus for computing a metric corresponding to a patient'"'"'s cardiac output, the apparatus comprising:
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a bioelectrical impedance recorder; an endotracheal tube having a proximal portion, a distal portion, and a longitudinal axis; first, second, third and fourth sense electrodes disposed on the distal portion and electrically coupled to the bioelectrical impedance recorder, the first and second sense electrodes spaced apart a first distance along the longitudinal axis, the third and fourth sense electrodes circumferentially spaced apart so that a line intersecting the first and second sense electrodes is substantially orthogonal to a line intersecting the third and fourth sense electrodes; means for urging the first, second, third and fourth electrodes against an interior wall of the patient'"'"'s airway; first and second current electrodes electrically coupled to the bioelectrical impedance recorder for injecting a sense current into the patient'"'"'s thorax, the first and second current electrodes spaced apart a second distance greater than the first distance, wherein the first, second, third and fourth sense electrodes generate a signal corresponding to the bioelectrical impedance of blood flow through the aorta and the signal is provided to the bioelectrical impedance recorder. - View Dependent Claims (34, 35, 36, 37, 38)
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Specification