Hematocrit measuring apparatus
First Claim
1. Apparatus for measuring the hematocrit of a flowing bloodstream in real time, comprising:
- (a) transparent cuvette means for containing said flowing bloodstream;
(b) infrared light source means adjacent said cuvette means for illuminating said bloodstream;
(c) detector means adjacent said cuvette means for detecting said infrared light after diffusion thereof by said bloodstream; and
(d) signal-producing means for producing a hematocrit signal which is a predetermined function of said detected diffused light;
(e) second detector means for compensating said first-named detector means; and
(f) second light source means for directly illuminating the said second detector means, said second light source and said first-named light source being connected in series;
(g) said signal-producing means being arranged to produce a hematocrit signal which is a function of the ratio of the light values senses by said first-named and second detector means, respectively.
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0 Petitions
Accused Products
Abstract
The hematocrit of a volume of blood can be determined in real time without volume or flow rate limitations by sensing the diffusion of infrared light by the bloodstream. For this purpose, an infrared light beam is directed at a transparent cuvette through which the blood is conveyed, and a photodetector is mounted beside the cuvette at an angle such that the intersection of the light beam and of the principal sensitivity lobe of the detector is wholly spaced from the multiple scatter zone adjacent to the light source. The hematocrit signal produced by the photodetector can be corrected for the effect of oxygen saturation by providing an oxygen saturation signal, multiplying the hematocrit signal by a function of the oxygen saturation signal and using a look-up table to derive a linear true hematocrit signal. Means are also provided to compensate the detected hematocrit signal for the effects of temperature, drive current, and aging.
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Citations
19 Claims
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1. Apparatus for measuring the hematocrit of a flowing bloodstream in real time, comprising:
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(a) transparent cuvette means for containing said flowing bloodstream; (b) infrared light source means adjacent said cuvette means for illuminating said bloodstream; (c) detector means adjacent said cuvette means for detecting said infrared light after diffusion thereof by said bloodstream; and (d) signal-producing means for producing a hematocrit signal which is a predetermined function of said detected diffused light; (e) second detector means for compensating said first-named detector means; and (f) second light source means for directly illuminating the said second detector means, said second light source and said first-named light source being connected in series; (g) said signal-producing means being arranged to produce a hematocrit signal which is a function of the ratio of the light values senses by said first-named and second detector means, respectively. - View Dependent Claims (2)
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3. Apparatus for measuring the hematocrit of a flowing bloodstream in real time, comprising:
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(a) first means for producing a first hematocrit signal which is a function of the diffusion of an infrared light beam by said bloodstream; (b) second means for producing a signal representative of the oxygen saturation of said bloodstream; (c) third means for multiplying said first hematocrit signal by a function of said oxygen saturation signal to produce an adjusted hematocrit signal; and (d) look-up table means for producing a linear hematocrit signal from predetermine combinations of said first hematocrit and oxygen saturation signal. - View Dependent Claims (4, 5, 6)
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7. Apparatus for measuring the hematocrit of a flowing bloodstream in real time, comprising:
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(a) a cuvette adapted to have a bloodstream flowing therethrough, said cuvette having a longitudinal axis; (b) a holder for receiving said cuvette; (c) first light source and photodetector means mounted, respectively, in said holder so as to detect only diffused light; (d) second light source and photodetector means mounted in said holder so as to detect multiple-scattered light; (e) third light source and photodetector means mounted in said holder in a position to only see each other; and (f) resilient, transparent, thermally conductive encapsulation means for providing a seat for positioning said cuvette in said holder, said encapsulation means enclosing all of said light source and photodetector means and maintaining them at substantially the same temperature. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A cuvette for use in determining the hematocrit of a flowing bloodstream as a function of oxygen saturation, comprising:
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(a) a substantially cylindrical body having a central portion with a plurality of longitudinally extending flat sides forming an acute angle with each other, and (b) an opaque cover fixed with respect to said body on the side opposite said flat sides. - View Dependent Claims (14, 15)
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16. Apparatus for measuring the hematocrit of a flowing bloodstram in real time, comprising:
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(a) transparent cuvette means for containing said flowing bloodstream; (b) infrared light source means adjacent said cuvette means for illuminating said bloodstream; (c) detector means adjacent said cuvette means for detecting said infrared light after diffusion thereof by said bloodstream; (d) signal-producing means for producing a hematocrit signal which is a predetermined function of said detected diffused light; and (e) said infrared light source means being arranged to emit a beam of light, said detector means having a restricted field of vision, and the intersection of said beam and field being sufficiently deep within said bloodstream to cause said detector means to see substantially only light diffused by said bloodstream. - View Dependent Claims (17)
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18. A method for measuring the hematocrit of a flowing bloodstream in real time, comprising the steps of:
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(a) illuminating said bloodstream with light; (b) detecting a first portion of said light diffused by said bloodstream; (c) detecting a second portion of said light multiple-scattered by said bloodstream; (d) producing an oxygen saturation signal which is a function of said detected multiple-scattered light portion; (e) producing a first hematocrit signal which is a function of said detected diffused light portion; and (f) using said oxygen saturation signal to adjust said first hematocrit signal so as to produce a second hematocrit signal which is independent of oxygen saturation. - View Dependent Claims (19)
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Specification