Methods of and apparatus for determining fluid volume presence in mammalian tissue
First Claim
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1. A method of determining the presence of fluid volume in mammalian tissue of a mammal having a body, comprising:
- providing a first set of injection electrodes and a second set of measurement electrodes;
positioning members of the first set of electrodes on the body to introduce electrical current flow through the mammalian tissue and thereby establish flow paths that define injection vectors along which electrical currents flow between two or more injection electrodes;
positioning members of the second set of electrodes on the body to define measurement vectors relating to electrical voltages produced in response to the electrical currents flowing between the injection electrodes, the injection and measurement vectors defining an anatomical space of the mammalian tissue;
deriving from each of different pairs of the injection and measurement vectors an electrical bio-impedance value that is characteristic of the electrical bio-impedance of a region of the anatomical space; and
analyzing the electrical bio-impedance values to detect a presence of a volume of fluid or change in a volume of fluid in the anatomical space.
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Abstract
Methods and apparatus (20 ) process noninvasively measured electrical bio-impedence values and perform a technique that indicates whether there exists a change from a homeostatic fluid condition, preferably with respect to blood loss, in mammalian tissue. Analyses can be performed to determine a presence or a change in volume of fluid in an anatomical space of a mammal. A preferred implementation of such technique is embodied in an instrument that carries out a method that may predict an onset of a hemorrhagic shock condition.
93 Citations
26 Claims
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1. A method of determining the presence of fluid volume in mammalian tissue of a mammal having a body, comprising:
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providing a first set of injection electrodes and a second set of measurement electrodes;
positioning members of the first set of electrodes on the body to introduce electrical current flow through the mammalian tissue and thereby establish flow paths that define injection vectors along which electrical currents flow between two or more injection electrodes;
positioning members of the second set of electrodes on the body to define measurement vectors relating to electrical voltages produced in response to the electrical currents flowing between the injection electrodes, the injection and measurement vectors defining an anatomical space of the mammalian tissue;
deriving from each of different pairs of the injection and measurement vectors an electrical bio-impedance value that is characteristic of the electrical bio-impedance of a region of the anatomical space; and
analyzing the electrical bio-impedance values to detect a presence of a volume of fluid or change in a volume of fluid in the anatomical space. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An instrument for determining a presence of or change in fluid volume in mammalian tissue of a mammal having a body, comprising:
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an injection current source of injection electrical current;
multiple electrodes configured for operative coupling to the injection current source and for placement on the body to introduce injection electrical current flow through the mammalian tissue and thereby establish flow paths that define injection vectors along which electrical currents flow between two or more injection electrodes;
multiple electrodes configured for placement on the body to define measurement vectors relating to electrical voltages produced in response to the electrical currents flowing between the injection electrodes;
sensor amplifier circuitry operatively coupled to the electrodes defining the measurement vectors to amplify the electrical voltages produced; and
processor circuitry operatively connected to the injection current source and the sensor amplifier circuitry, the processor circuitry programmed with instructions to process signals representing the injection electrical currents and the produced voltages corresponding to different pairs of the injection and measurement vectors, to compute from each of different pairs of the injection and measurement vectors an electrical bio-impedance value that characterizes the electrical bio-impedance of the mammalian tissue in an anatomical space, and to analyze the electrical bio-impedance values to detect a presence of or a change in a volume of fluid in the anatomical space. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification