MEASUREMENT OF HEMATOCRIT AND CARDIAC OUTPUT FROM OPTICAL TRANSMISSION AND REFLECTION CHANGES
First Claim
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1. A method of determining cardiac output of a subject comprising:
- a) illuminating the cardiovascular system of the subject with an excitation light;
b) detecting the intensity (x) of the excitation light that is reflected by a portion of the cardiovascular system;
c) detecting the intensity (y) of the excitation light that is transmitted through a portion of the cardiovascular system;
d) determining the concentration of hematocrit from the ratio of (y)/(x);
e) injecting a predetermined quantity of fluid into the cardiovascular system;
f) repeating steps a) through d);
g) determining the hematocrit change trace integrated over time; and
h) determining the subjects'"'"' cardiac output based on the quantity of injected fluid and the hematocrit change trace integrated over time.
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Abstract
A system and method of non-invasive determination of hematocrit change from optical reflected light in combination with transmitted light or from reflected light measured from one or more locations on a blood carrying medium. Determining the cardiac output of a patient based on the amount of plasma or saline injected and the determined hematocrit change. The cardiac output may be determined on a patient undergoing hemodialysis. The hematocrit changes can be detected transcutaneously, transarterially, intraarterially, or across an extracorporeal arterial circulatory path.
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Citations
12 Claims
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1. A method of determining cardiac output of a subject comprising:
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a) illuminating the cardiovascular system of the subject with an excitation light; b) detecting the intensity (x) of the excitation light that is reflected by a portion of the cardiovascular system; c) detecting the intensity (y) of the excitation light that is transmitted through a portion of the cardiovascular system; d) determining the concentration of hematocrit from the ratio of (y)/(x); e) injecting a predetermined quantity of fluid into the cardiovascular system; f) repeating steps a) through d); g) determining the hematocrit change trace integrated over time; and h) determining the subjects'"'"' cardiac output based on the quantity of injected fluid and the hematocrit change trace integrated over time. - View Dependent Claims (2, 3, 4)
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5. A method of determining cardiac output of a subject comprising:
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a) illuminating the cardiovascular system of the subject with an excitation light; b) detecting the intensity (x) of the excitation light that is reflected by a portion of the cardiovascular system at a first location; c) detecting the intensity (y) of the excitation light that is reflected by a portion of the cardiovascular system at a second location; d) determining the concentration of hematocrit from the ratio of (y)/(x); e) injecting a predetermined quantity of fluid into the cardiovascular system; f) repeating steps a) through d); g) determining the hematocrit change trace integrated over time; and h) determining the subjects'"'"' cardiac output based on the quantity of injected fluid and the hematocrit change trace integrated over time. - View Dependent Claims (6, 7, 8)
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9. A system for determining cardiac output of a subject comprising:
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a) an illumination source configured to be positioned proximately to at least one blood vessel of the cardiovascular system to provide a wavelength of light to the cardiovascular system; b) at least one photodetector configured to be positioned proximate to the cardiovascular system of the subject so as to detect information regarding the intensity (x) of the excitation light that is reflected by a portion of the cardiovascular system and to detect information regarding the intensity (y) of the excitation light that is transmitted through the cardiovascular system, and to detect a quantity of injected fluid in the cardiovascular system; and c) a computing system configured to receive the detected intensity information from the photodetector and to determine the concentration of hematocrit from the ratio of (y)/(x); and
configured to compute a hematocrit change trace integrated over time; and
further configured to determine the subjects'"'"' cardiac output based on the measured quantity of injected fluid and the computed hematocrit change trace integrated over time. - View Dependent Claims (10, 11, 12)
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Specification