Apparatus for measuring hemoglobin concentration and oxygen saturation thereof

Claim 1

An apparatus for measuring a degree of oxygen saturation in blood, comprising: source means for emitting light at a first and second wavelength (λ 1 , λ 2 ), with a difference of a degree of extinction between oxygenated hemoglobin and carbomonoxy hemoglobin being comparatively large at said first wavelength and small at said second wavelength; first light-irradiating means having a first light-irradiating portion, and being coupled to said source means for alternately irradiating blood with light of said first or second wavelength (λ 1 , λ 2 ); second light irradiating means having a second light-irradiating portion, and being coupled to said source means for constantly irradiating the blood with light of said second wavelength λ 2 ; detecting means, arranged such that the distance from the detecting means to said first light-irradiating means and the distance from the detecting means to said second light-irradiating means differ, for detecting intensities (I 1 , I 2 , I 3 ) of light reflected from the blood irradiated with the light from each of the first and second light-irradiating portions of said first and second light-irradiating means corresponding to their wavelength; memory means for storing an Hb calibration curve; arithmetic means for calculating a reflected-light intensity ratio function g(Hb') of blood having a reference value (Hb') of hemoglobin concentration by reference to said Hb calibration curve stored in said memory means; first corrective value calculating means for calculating a first corrective value (X) based on both a reflected-light intensity ratio (I 2 /I 3 ) s ) from a blood with known hemoglobin concentration and said reflected-light intensity ratio function, according to an equation X=g(Hb')×(I 2 /I 3 )/(I 2 /I 3 ) s , to correct a ratio (I 2 /I 3 ) of detected reflected-light intensity (I 2 ) due to irradiation with light of said second wavelength produced by said first light-irradiating means versus detected reflected-light intensity (I 3 ) due to irradiation with light of said second wavelength produced by said second light-irradiating means; second corrective values calculating means for calculating a second corrective value (C 1 ) based on said first corrective value (X), the reflected-light intensity (I 3 ) of light from the second light-irradiating means detected continuously by said detecting means, and a constant value (C 0 ), according to an equation C 1 =C 0 ×(I 3 )×(X); reflected-light intensity ratio correcting means for correcting to remove an influence of hematocrit value and for calculating a corrected reflected-light intensity ratio (R s ) based on said second corrective value (C 1 ), a reflected-light intensity ratio (I 1 /I 2 ) of the detected reflected-light intensity (I 1 ) of light of said first wavelength produced by the first light-irradiating means versus detected reflected-light intensity (I 2 ) of light of said second wavelength produced by the first light-irradiating means, according to an equation R s =(I 1 -C 1 )/(I 2 -C 1 ); and oxygen saturation degree calculating means for calculating the degree of oxygen saturation in blood based on a correlation function (f(x)) using the corrected reflected light intensity ratio (R s ) outputted by said reflected light intensity ratio correcting means.

Claim 2

An apparatus for measuring a degree of oxygen saturation in blood, comprising: source means for emitting light at a first and second wavelength (λ 1 , λ 2 ), with a difference of a degree of extinction between oxygenated hemoglobin and carbomonoxy hemoglobin being comparatively large at said first wavelength and small at said second wavelength; first light-irradiating means having a first light-irradiating portion, and being coupled to said source means for alternately irradiating blood with light of said first or second wavelength (λ 1 , λ 2 ); second light irradiating means having a second light-irradiating portion, and being coupled to said source means for constantly irradiating the blood with light of said second wavelength λ 2 ; detecting means, arranged such that the distance from the detecting means to said first light-irradiating means and the distance from the detecting means to said second light-irradiating means differ, for detecting intensities (I 1 , I 2 , I 3 ) of light reflected from the blood irradiated with the light from each of the first and second light-irradiating portions of said first and second light-irradiating means corresponding to their wavelength; memory means for storing an Hb calibration curve; arithmetic means for calculating a reflected-light intensity ratio function g(Hb') of blood having a reference value (Hb') of hemoglobin concentration by reference to said Hb calibration curve stored in said memory means; first corrective value calculating means for calculating a first corrective value (X) based on both a reflected-light intensity ratio (I 2 /I 3 ) s ) from a blood with known hemoglobin concentration and said reflected-light intensity ratio function, according to an equation X=g(Hb')×(I 2 /I 3 )/(I 2 /I 3 ) s , to correct a ratio (I 2 /I 3 ) of detected reflected-light intensity (I 2 ) due to irradiation with light of said second wavelength produced by said first light-irradiating means versus detected reflected-light intensity (I 3 ) due to irradiation with light of said second wavelength produced by said second light-irradiating means; second corrective values calculating means for calculating a second corrective value (C 1 ) based on said first corrective value (X), the reflected-light intensity (I 3 ) of light from the second light-irradiating means detected continuously by said detecting means, and a constant value (C 0 ), according to an equation C 1 =C 0 ×(I 3 )×(X); reflected-light intensity ratio correcting means for correcting to remove an influence of hematocrit value and for calculating a corrected reflected-light intensity ratio (R s ) based on said second corrective value (C 1 ), a reflected-light intensity ratio (I 1 /I 2 ) of the detected reflected-light intensity (I 1 ) of light of said first wavelength produced by the first light-irradiating means versus detected reflected-light intensity (I 2 ) of light of said second wavelength produced by the first light-irradiating means, according to an equation R s =(I 1 -C 1 )/(I 2 -C 1 ); and oxygen saturation degree calculating means for calculating the degree of oxygen saturation in blood based on a correlation function (f(x)) using the corrected reflected light intensity ratio (R s ) outputted by said reflected light intensity ratio correcting means.

Claim 8

An apparatus for measuring hemoglobin concentration in blood, comprising: source means for emitting light at a specific wavelength (λ 2 ), with a difference of a degree of extinction between oxygenated hemoglobin and carbomonoxy hemoglobin being comparatively small; first and second light-irradiating means having first and second light-irradiating portions, respectively, and being coupled respectively to said source means for irradiating blood with light of said specific wavelength (λ 2 ) from different directions; detecting means, arranged such that the distance from the detecting means to said first light-irradiating means and the distance from the detection means to said second light-irradiating means differ, for detecting intensities (I 1 /I 2 ) of light reflected from the blood irradiated with the light from the first and second light-irradiating portions of said first and second light-irradiating means; corrective coefficient calculating means for calculating a corrective coefficient (A) based on a ratio of a ratio (I 1 /I 2 ) of the reflected-light intensity (I 1 ) of light from said first light-irradiating means to the reflected-light intensity (I 2 ) of light from said second light-irradiating means to a ratio ((I 1 /I 2 ) s ) of intensities of reflected-light from a blood with known hemoglobin concentration irradiated by said first and second light-irradiating means, according to an equation A=((I 1 /I 2 ) s /(I 1 /I 2 )); reflected-light intensity ratio correcting means for multiplying a reflected-light intensity ratio (I 1 /I 2 ) by said corrective coefficient (A) to obtain a corrected reflected-light ratio (R s ); and hemoglobin concentration calculating means for calculating the hemoglobin concentration in blood based on a correlation function h(R s ) using the corrected reflected-light intensity ratio (R s ) outputted by said reflected light intensity ratio correcting means.

Claim 9

An apparatus for measuring hemoglobin concentration in blood, comprising: source means for emitting light at a specific wavelength (λ 2 ), with a difference of a degree of extinction between oxygenated hemoglobin and carbomonoxy hemoglobin being comparatively small; first and second light-irradiating means having first and second light-irradiating portions, respectively, and being coupled respectively to said source means for irradiating blood with light of said specific wavelength (λ 2 ) from different directions; detecting means, arranged such that the distance from the detecting means to said first light-irradiating means and the distance from the detection means to said second light-irradiating means differ, for detecting intensities (I 1 /I 2 ) of light reflected from the blood irradiated with the light from the first and second light-irradiating portions of said first and second light-irradiating means; corrective coefficient calculating means for calculating a corrective coefficient (A) based on a ratio of a ratio (I 1 /I 2 ) of the reflected-light intensity (I 1 ) of light from said first light-irradiating means to the reflected-light intensity (I 2 ) of light from said second light-irradiating means to a ratio ((I 1 /I 2 ) s ) of intensities of reflected-light from a blood with known hemoglobin concentration irradiated by said first and second light-irradiating means, according to an equation A=((I 1 /I 2 ) s /(I 1 /I 2 )); reflected-light intensity ratio correcting means for multiplying a reflected-light intensity ratio (I 1 /I 2 ) by said corrective coefficient (A) to obtain a corrected reflected-light ratio (R s ); and hemoglobin concentration calculating means for calculating the hemoglobin concentration in blood based on a correlation function h(R s ) using the corrected reflected-light intensity ratio (R s ) outputted by said reflected light intensity ratio correcting means.