Evaluating cardiovascular health using intravascular volume
First Claim
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1. A method for evaluating cardiovascular condition of a patient, the method comprising:
- (a) recording a first impedance of a limb or extremity or neck of the patient at a first time in response to receiving a first impedance reading from a plurality of sensors on a limb or extremity or neck;
(b) after the occurrence of an event modulating blood return to the heart via the venous system of the patient, recording a second impedance of the limb or extremity or neck at a second time in response to receiving a second impedance reading from a plurality of sensors on a limb or extremity or neck, wherein the first impedance and the second impedance each correspond to a volume of blood flowing within the limb or extremity or neck;
(c) determining a change in venous blood volume between the first time and the second time by comparing the first impedance and the second impedance to determine a change in volume of blood; and
(d) determining, based on the change in venous blood volume between the first time and the second time, one or more of;
(1) how the patient will hemodynamically respond to one or more of an addition of cardiovascular fluid or removal of cardiovascular fluid,(2) how the patient will hemodynamically respond to one or more cardiovascular drugs which promote changes in cardiac output, changes in cardiovascular preload, and changes in cardiovascular afterload, or(3) how the patient will hemodynamically respond to changes in mechanical or noninvasive ventilation.
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Abstract
Non-invasive monitoring of cardiovascular health is performed by monitoring changes in the volume of blood in the venous side of the vascular system. The blood volume changes are determined from measurements of bioimpedance of limbs or neck, in particular changes in bioimpedance in response to blood modulating events performed on the limbs or neck, where bioimpedance is measured and compared before and after such events.
23 Citations
28 Claims
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1. A method for evaluating cardiovascular condition of a patient, the method comprising:
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(a) recording a first impedance of a limb or extremity or neck of the patient at a first time in response to receiving a first impedance reading from a plurality of sensors on a limb or extremity or neck; (b) after the occurrence of an event modulating blood return to the heart via the venous system of the patient, recording a second impedance of the limb or extremity or neck at a second time in response to receiving a second impedance reading from a plurality of sensors on a limb or extremity or neck, wherein the first impedance and the second impedance each correspond to a volume of blood flowing within the limb or extremity or neck; (c) determining a change in venous blood volume between the first time and the second time by comparing the first impedance and the second impedance to determine a change in volume of blood; and (d) determining, based on the change in venous blood volume between the first time and the second time, one or more of; (1) how the patient will hemodynamically respond to one or more of an addition of cardiovascular fluid or removal of cardiovascular fluid, (2) how the patient will hemodynamically respond to one or more cardiovascular drugs which promote changes in cardiac output, changes in cardiovascular preload, and changes in cardiovascular afterload, or (3) how the patient will hemodynamically respond to changes in mechanical or noninvasive ventilation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A testing apparatus for evaluating cardiovascular condition of a patient, the testing apparatus comprising:
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one or more electrodes; one or more processors; a computer-readable memory storing non-transient instructions that when executed by the one or more processors cause the testing apparatus to; (a) use the one or more electrodes to record a first impedance of a limb or extremity or neck of the patient at a first time in response to receiving a first impedance reading from a plurality of sensors on a limb or extremity or neck; (b) after the occurrence of an event modulating blood return to the heart via the venous system of the patient, use the one or more electrodes to record a second impedance of the limb or extremity or neck at a second time in response to receiving a second impedance reading from a plurality of sensors on a limb or extremity or neck, wherein the first impedance and the second impedance each correspond to a volume of blood flowing within the limb or extremity or neck; (c) determine a change in venous blood volume between the first time and the second time by comparing the first impedance and the second impedance to determine a change in volume of blood; and (d) determine, based on the change in venous blood volume between the first time and the second time, one or more of; (1) how the patient will hemodynamically respond to one or more of an addition of cardiovascular fluid or removal of cardiovascular fluid, (2) how the patient will hemodynamically respond to one or more cardiovascular drugs which promote changes in cardiac output, changes in cardiovascular preload, and changes in cardiovascular afterload, or (3) how the patient will respond hemodynamically to changes in mechanical or noninvasive ventilation. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A method for evaluating cardiovascular condition of a patient, the method comprising:
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(a) recording a first impedance of a limb or extremity or neck of the patient at a first time in response to receiving a first impedance reading from a plurality of sensors on a limb or extremity or neck; (b) after the occurrence of an event modulating blood return to the heart via the venous system of the patient, recording a second impedance of the limb or extremity or neck at a second time in response to receiving a second impedance reading from a plurality of sensors on a limb or extremity or neck, wherein the first impedance and the second impedance each correspond to a volume of blood flowing within the limb or extremity or neck; (c) determining a change in venous blood volume between the first time and the second time by comparing the first impedance and the second impedance to determine a change in volume of blood; and (d) determining, based on the change in venous blood volume between the first time and the second time, one or more of changes in vena cava diameter, central venous pressure, right atrial venous pressure from the change in venous blood volume, or respiratory rate and effort from the change in venous blood volume. - View Dependent Claims (23, 24, 25, 26, 27, 28)
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Specification