JP2017205204A - Hematocrit value measuring device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further increase hematocrit value measurement accuracy.SOLUTION: A hematocrit value measuring device includes a first light source 1 (1-1) for irradiating a light of a first wavelength λA onto a biological tissue 303 including a blood vessel 301, a second light source 1 (1-2) for irradiating a light of a second wavelength λB different from the first wavelength λA onto the biological tissue 303 including the blood vessel 301, and a light detector 2 for detecting light volume of the light of the first wavelength λA and the light of the second wavelength λB diffused and propagated in the biological tissue 303 and emitted to the outside as diffuse reflection light volume. The light of the first wavelength λA is a light of a wavelength exhibiting main absorption to hemoglobin, and the light of the second wavelength λB is a light of a wavelength exhibiting an equal light absorption coefficient to hemoglobin and water.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hematocrit value measuring apparatus and method for measuring a volume ratio of red blood cells in blood flowing through a blood vessel as a hematocrit value.

  Conventionally, a wearable sensor system has been used as a device for detecting biological information. In this wearable sensor system, various sensors can be attached to a shirt, wrist, upper arm, etc., and biological information that changes from moment to moment can be monitored.

  FIG. 15 shows an example of a wearable sensor system. The wearable sensor system 100 includes a blood flow sensor 101 on the wrist, a cardiac potential sensor 102 having electrodes on clothing, and a hematocrit value sensor 103 on the ear. The hematocrit value sensor 103 detects the volume ratio of red blood cells in the blood flowing through the blood vessel as a hematocrit value.

  As an adverse event recognized by the hematocrit value detected by the hematocrit value sensor 103, in daily life, an increase in hematocrit value caused by dehydration symptoms due to heat stroke (dehydration symptoms of people in a hot environment), and a hematocrit value caused by anemia due to kidney disease Decrease. Further, it is known that an artificial dialysis apparatus which is an extracorporeal circulation apparatus has a decrease in hematocrit value due to blood pressure decrease due to water removal, and an artificial heart has an increase in hematocrit value due to bleeding by a blood anticoagulant.

  In general, such a hematocrit value is measured by using a microhematocrit centrifugal method, a blood gas analyzer, or the like. In this general method, since blood is collected in the test, continuous measurement (monitoring) is difficult. In order to solve such a problem, a sensor technique for grasping a blood state without collecting blood using near infrared light is known. This sensor technology using near-infrared light is effective for monitoring that can provide clinically important knowledge.The absorbance of water has a wavelength that is greater than that of hemoglobin, and the absorbance of hemoglobin is greater than that of water. A method of estimating using two wavelengths is used.

  For example, as shown in FIG. 16, as non-invasive hematocrit measurement for the dialysis tube 201, scattered light of different wavelengths 810 nm and 1300 nm of two near-infrared light emitting diodes (LEDs) 202 and 203 (light source) are converted into photodiodes 204, There is a method of detecting a hematocrit value in blood 206 based on a difference from the isosbestic points of red blood cells and plasma detected by 205 (light detector) (for example, see Non-Patent Document 1). Materials such as silicon, GaAlAs, and InGaAsP are used for the diodes 202 and 203 and the photodiodes 204 and 205 according to the wavelength range. In this method, the optical path length through which light propagates can be defined from the physical size of the tube, so the relational expression between the diffuse reflection light quantity and the hematocrit value can be obtained from the measurement results at two points using a predetermined proportional coefficient. it can.

  On the other hand, in the application to biological tissue, the average value of diffuse transmitted light intensity at a predetermined light wavelength and the ratio of peak / valley are measured using the expansion (expansion) / contraction of the artery due to pulsation, In order to measure the signal that is in phase with arterial blood by excluding the signal and to normalize the optical path length through which the light propagates, it is calculated statistically after taking the ratio of the diffuse transmitted light intensity of two different wavelengths. A method of estimating a hematocrit value with a polynomial constituted by a predetermined coefficient and a diffuse reflection light intensity ratio is known (see, for example, Patent Document 1).

  In the method disclosed in Patent Document 1, variation in tissue water content is an issue, and the accuracy of the hematocrit value measured due to the effect of variation in the ratio of water content (tissue water ratio) contained in living tissue. Decreases. From this, in addition to the above-mentioned two wavelengths, there is known a method for estimating a hematocrit value corresponding to a difference in water ratio at multiple wavelengths (see, for example, Patent Document 2). In addition, in order to reduce measurement errors caused by water absorption characteristics due to skin temperature, a method for estimating a hematocrit value by controlling the skin temperature is also known (see, for example, Patent Document 3).

Japanese National Patent Publication No. 09-508291 JP-T-2004-523320 Special table 2003-533261 gazette

Shota Ekuni, Yoshiyuki Sankai, “Non-invasive and continuous hematocrit measurement by optical method without calibration”, IEEJ Transactions on Electronics, Information and Systems, Vol.135, No.4, pp.387-395 .

  However, it is known that the conventional hematocrit value measuring device for living tissue depends on the light absorption and light scattering also with respect to the hematocrit value and the tissue moisture ratio. Even if the ratio of the two wavelengths is taken, errors due to the amount of tissue water and light scattering cannot be completely excluded, and there is a problem that it is difficult to increase the measurement accuracy of the hematocrit value.

  The present invention has been made to solve such problems, and an object of the present invention is to provide a hematocrit value measuring apparatus and method capable of further increasing the measurement accuracy of the hematocrit value.

  In order to achieve such an object, the present invention provides a hematocrit value measuring device (10) for measuring a volume ratio of red blood cells in blood flowing through a blood vessel (301) as a hematocrit value. 303) a first light source (1-1) for irradiating light of a first wavelength (λA) to the living body tissue (303) including a blood vessel (301), and a first wavelength (λA) Is a second light source (1-2) that emits light of a different second wavelength (λB), and light of the first wavelength (λA) that is diffused and propagated through the living tissue (303) and emitted to the outside. And a photodetector (2) that detects the amount of light of the second wavelength (λB) as the amount of diffusely reflected light, of the light of the first wavelength (λA) and the light of the second wavelength (λB) One is characterized by light having a wavelength exhibiting an equal light absorption coefficient between hemoglobin and water.

In the present invention, the first light source (1-1) irradiates the biological tissue (303) including the blood vessel (301) with the light having the first wavelength (λA), and the second light source (1-2). To the biological tissue (303) including the blood vessel (301) is irradiated with light having the second wavelength (λB). The irradiated light of the first wavelength (λA) and the light of the second wavelength (λB) are different in wavelength. In addition, one of the light of the first wavelength (λA) and the light of the second wavelength (λB) is light having a wavelength exhibiting an equal light absorption coefficient between hemoglobin and water. For example, light having the first wavelength (λA) is light having a wavelength that exhibits major absorption in hemoglobin, and light having the second wavelength (λB) is light having a wavelength that exhibits the same light absorption coefficient between hemoglobin and water. . In the present invention, when the light absorption coefficient of hemoglobin is μ _aHb and the light absorption coefficient of water is μ _aw , the equal light absorption coefficient means μ _{aHb ≈μ aw} . Further, the equivalent optical absorption coefficient of light absorption coefficient of hemoglobin Ganmamyu _AHB, if the light absorption coefficient of water was equivalent light absorption coefficient Itamyu _aw, refers to a _γμ aHb ≒ ημ _aw.

  In the present invention, one of the light of the first wavelength (λA) and the light of the second wavelength (λB) is light having a wavelength that exhibits the same light absorption coefficient between hemoglobin and water. The ratio of the amount of water contained in the living tissue (303) is calculated as the tissue moisture ratio from the variation in the amount of diffusely reflected light of the light having the same light absorption coefficient, and the calculated tissue moisture ratio is used to calculate the other By correcting the hematocrit value calculated from the variation in the amount of diffusely reflected light of the wavelength of the light, the true hematocrit value that excludes the influence of the amount of water contained in the biological tissue (303) is estimated, and the hematocrit value It is possible to further increase the measurement accuracy.

  In the above description, as an example, constituent elements on the drawing corresponding to the constituent elements of the invention are indicated by reference numerals with parentheses.

  As described above, according to the present invention, an optical hematocrit value is obtained by setting one of the first wavelength light and the second wavelength light to a wavelength exhibiting an equal light absorption coefficient between hemoglobin and water. It is possible to further increase the measurement accuracy.

FIG. 1 is a diagram showing a configuration of a main part of a hematocrit value measuring apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a state in which light (near infrared light) is applied to the skin from a light source. FIG. 3 is a diagram showing changes in light absorption of blood cells and changes in light absorption of water in blood when blood vessels are expanded and contracted due to pulsation. FIG. 4 is a diagram showing the wavelength dependence (spectral spectrum) of the light series coefficients of hemoglobin (Hb) and water (water). FIG. 5 is a diagram schematically illustrating an optical path in a living tissue. FIG. 6 is a diagram schematically showing an optical path in a living tissue. FIG. 7 is a diagram showing the detection position dependence of the diffuse reflection light amount difference ΔRd with respect to the hematocrit value H and the tissue moisture ratio Fw when the wavelength is 800 nm. FIG. 8 is a diagram showing the detection position dependence of the diffuse reflection light amount difference ΔRd with respect to the hematocrit value H and the tissue moisture ratio Fw when the wavelength is 1000 nm. FIG. 9 is a diagram showing the diffuse reflection light amount difference ΔRd with respect to the hematocrit value H at a detection position of 3 mm with a wavelength of 800 nm. FIG. 10 is a diagram for explaining selection of wavelengths that exhibit the same light absorption coefficient between hemoglobin and water. FIG. 11 is a diagram showing the detection position dependence of the diffuse reflection light amount difference ΔRd with respect to the hematocrit value H and the tissue moisture ratio Fw when the wavelength is 1400 nm. FIG. 12 is a diagram schematically showing the wavelength dependence of the equivalent light absorption coefficient in the vicinity of λ = 1200 to 1300 nm. FIG. 13 is a diagram showing the detection position dependence of the diffuse reflection light amount difference ΔRd with respect to the hematocrit value H and the tissue moisture ratio Fw when the wavelength is 1300 nm. FIG. 14 is a diagram showing a diffuse reflection light amount difference ΔRd with respect to Fw at a detection position of 3 mm near a wavelength of 1300 nm. FIG. 15 is a diagram illustrating an example of a wearable sensor system. FIG. 16 is a diagram for explaining noninvasive hematocrit measurement on a dialysis tube.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of a main part of a hematocrit value measuring apparatus according to an embodiment of the present invention. The hematocrit value measuring apparatus 10 includes a first light source 1 (1-1) that irradiates a living tissue 303 including a blood vessel 301 with light having a first wavelength λA (near infrared light) from the skin 302 side; A second light source 1 (1-2) that irradiates the living tissue 303 including the blood vessel 301 with light (near infrared light) having a second wavelength λB different from the first wavelength λA from the skin 302 side; A light detector 2 that detects the amount of light of the first wavelength λA and the light of the second wavelength λB that are diffused and propagated through the living tissue 303 as a diffuse reflected light amount; and a hematocrit value calculation processing unit 3 And.

  In this hematocrit value measuring apparatus 10, the light having the first wavelength λA is light having a wavelength that exhibits major absorption in hemoglobin, and the light having the second wavelength λB has light having a wavelength that exhibits the same light absorption coefficient between hemoglobin and water. It is said to be light. In addition, the hematocrit value calculation processing unit 3 includes a first diffuse reflection light amount variation observation unit 31, a second diffuse reflection light amount variation observation unit 32, a hematocrit value calculation unit 33, a tissue moisture ratio calculation unit 34, and a hematic. The value estimation unit 35 is provided, and is realized by hardware including a processor and a storage device, and a program that realizes various functions in cooperation with the hardware.

  The first diffuse reflection light quantity fluctuation observation unit 31 observes the fluctuation ΔRd (λA) of the diffuse reflection light quantity of the light of the first wavelength λA when the blood vessel 301 is expanded and contracted, and the second diffuse reflection light quantity fluctuation observation. The unit 32 observes a variation ΔRd (λB) in the amount of diffusely reflected light of the light having the second wavelength λB when the blood vessel 301 is expanded and contracted. The fluctuation ΔRd of the diffuse reflected light amount will be described later.

  The hematocrit value calculation unit 33 calculates the hematocrit value H of the blood flowing through the blood vessel 301 from the variation ΔRd (λA) of the diffuse reflection light amount of the light having the first wavelength λA observed by the first diffuse reflection light amount variation observation unit 31. To do. The tissue moisture ratio calculating unit 34 includes the amount of moisture contained in the living tissue 303 based on the variation ΔRd (λB) of the diffuse reflection light amount of the light having the second wavelength λB observed by the second diffuse reflection light amount variation observation unit 32. Is calculated as the tissue moisture ratio Fw. The hematic value estimation unit 35 corrects the hematocrit value H calculated by the hematocrit value calculation unit 33 using the tissue moisture ratio Fw calculated by the tissue moisture ratio calculation unit 34, thereby correcting the amount of moisture contained in the living tissue 303. A true hematocrit value Hct from which the influence is eliminated is estimated.

Hereinafter, the process up to the configuration of the hematocrit value measuring apparatus 10 will be described.
When measuring the hematocrit value H, as shown in FIG. 2, light (near infrared light) is irradiated from the light source 1 to the skin 302, diffused and propagated in the living tissue 303, and emitted to the outside of the skin 302. The amount of light to be detected is detected by the light detector 2 as the amount of diffusely reflected light.

  The measurement of blood components according to the contraction and dilation of blood vessels is well known by measuring oxidized and reduced hemoglobin with a pulse oximeter. The hematocrit value measuring apparatus 10 of the present embodiment also uses the light absorption change (see FIG. 3) during blood vessel dilation / contraction due to pulsation. In FIG. 3, I shows the change in light absorption of blood cells, and II shows the change in light absorption of water in the blood.

The diffusely reflected light _amounts I _cmp and I _exp at the time of expansion / contraction can be expressed by the following equation according to the D'Alembert law from the light absorption coefficient μ of the medium and the optical path length l.

Here, I ₀ is the amount of incident light, μ _ab is the light absorption coefficient of blood, μ _at is the light absorption coefficient of tissue, l _bc is the average optical path length in blood between the light source 1 and the light detector 2, and l _tc is the average optical path length in the tissue between the light source 1 and the photodetector 2.

As shown in FIG. 4, the light absorption of blood in the blood vessel is proportional to the hematocrit value in the range of 700 to 1000 [nm] in which oxidized / reduced hemoglobin exhibits dominant absorption. Light absorption by water in the skin and plasma in the blood is proportional to the amount of water in the tissue and the volume of water removed by blood cell components. From the above, if the light absorption coefficients of hemoglobin and water are μ _aHb and μ _aw , the light absorption coefficients μ _aHb and μ _aw can be expressed by the following equations.

  Here, H is a hematocrit value, Fw is a tissue moisture ratio, β is a proportional multiplier indicating the influence of protein or the like on the optical constant, and γ and η are proportional multipliers indicating the influence of the hematocrit value in blood on the optical constant. Actually, these constants are greatly influenced by individual differences and variations due to measurement sites, and it is assumed that absolute measurement errors will occur.

Next, the background absorption or the like in the living tissue 303 can be omitted by obtaining the fluctuation ΔRd of the diffuse reflected light amount at the wavelength λ when the blood vessel is expanded and contracted due to pulsation. As shown schematically in FIG. 5, the modulation of the optical absorption coefficient occurred in part of the optical path length .DELTA.l _b, diffuse reflected light is amplitude modulated. In fact .DELTA.l _b can not be uniquely determined by in vivo scattering. When an equivalent optical path length of .DELTA.l _b and .DELTA.l _d, variation ΔRd diffuse reflected light can be expressed by the following equation.

Next, when ΔRd in the vicinity of a wavelength of 800 nm (λ1) where the influence of oxygen saturation is small is obtained, Equation (5) is simplified by assuming μ _aHb >> μ _aw and Equation (6) below is obtained. can do.

Here, Δl _d1 is an equivalent optical path length at the detection position d. From formula (6), the hematocrit value H can be expressed as the following formula (7).

  Further, the hematocrit value H can be expressed as the following equation (8) from the difference between the detection position d and ΔRd at a position away from Δd in the vicinity.

  Based on Equation (7), the relationship between H and ΔRd is obtained from Monte Carlo calculation. Light scattering simulation by the Monte Carlo method was used to investigate the validity of the calculation model formula. It is possible to reproduce the propagation of light (boundary reflection / diffuse reflection / absorption / transmission) to a tissue composed of a plurality of layers. The expansion / contraction of the blood layer due to pulsation was expressed by changing the thickness of the blood layer. The hematocrit value when the hematocrit value H and the tissue moisture ratio Fw are varied is estimated. For example, the hematocrit value is estimated by varying the hematocrit value H = (0.2, 0.4, 0.6) and the tissue moisture ratio Fw = (0.4, 0.6, 0.8).

As shown in FIG. 6, the light incident position is set to X = 0 mm, and the amount of diffusely reflected light reaching the photodetector 2 after being scattered inside the living tissue 303 formed on the layer with respect to the detection position d is expressed as follows. Ask. For the living tissue 303, the light absorption coefficient and the light scattering coefficient obtained by spectroscopy were used. FIG. 7 shows the diffuse reflection light amount difference (variation of diffuse reflection light amount) ΔRd at different detection positions d for different H and Fw at a wavelength of 800 nm. For a different H, the slope of the substantially straight line also depends on γμ _aHb , and the diffuse reflection light amount difference ΔRd decreases with distance, but it can be seen that the influence of the slope is small on the tissue moisture ratio Fw.

Next, when ΔRd in the vicinity of a wavelength of 1000 nm (λ2) is obtained, μ _aHb > μ _aw , but since the absorption coefficient of water cannot be ignored, Equation (5) can be expressed by the following equation.

Similarly, FIG. 8 shows the diffuse reflection light amount difference ΔRd calculated at different detection positions for different H and Fw at a wavelength of 1000 nm. For different Hs, the slope of the substantially straight line depends on both γμ _aHb and μ _aw , the diffuse reflection light amount difference ΔRd decreases, and it can be seen that the influence of the tilt also occurs on the tissue moisture ratio Fw. . Therefore, the amount of change in tissue moisture may be affected.

  FIG. 9 is a diagram showing the diffuse reflection light amount difference ΔRd with respect to the hematocrit value H at the detection position (3 mm) when the wavelength is 800 nm. Although not clear in FIG. 7, when the tissue moisture ratio Fw is changed from 0.4 to 0.8, the diffuse reflection light amount difference ΔRd that cannot be ignored changes, and an H measurement error occurs. Since the influence of the tissue moisture ratio Fw cannot necessarily be ignored, correction of Fw is necessary.

In the correction of Fw, a method of selecting a wavelength _satisfying μ _aHb << μ _aw is known. FIG. 10 shows spectroscopic data. Using a wavelength of 1400 nm (λ4) where the absorption coefficient μ _{aHb of} hemoglobin can be ignored, equation (5) can be expressed by the following equation.

FIG. 11 shows the calculated diffuse reflection light amount difference ΔRd at different detection positions for different H and Fw at the wavelength of 1400 nm. As can be seen from the equation (10), it largely depends on the tissue moisture ratio Fw, but also depends on H, and therefore an error may occur in the estimated amount of Fw. In addition, it is clear that Δl _d4 is significantly different from Δl _d1 due to the difference in the absorption coefficient and scattering coefficient media, and it is not necessary to perform correction to eliminate the influence of Fw at a wavelength of 800 nm. Is appropriate.

Therefore, in the present embodiment, Fw is estimated more accurately by selecting a wavelength λ3 that is shorter than the wavelength of 1400 nm and satisfies γμ _aHb ≈ημ _aw . In this case, since Equation (5) satisfies _γHμ aHb ≈ηHμ _aw , it can be expressed as follows.

In this case, the actual light absorption coefficient of hemoglobin is μ _aHb , but the light absorption coefficient μ _aHb (equivalent light absorption coefficient γμ _aHb ) multiplied by the proportional constant η is treated as the light absorption coefficient of hemoglobin. The actual light absorption coefficient of water is μ _aw , but the light absorption coefficient μ _aw (equivalent light absorption coefficient ημ _aw ) multiplied by the proportional constant η is treated as the light absorption coefficient of water.

By selecting such two wavelengths (λ1, λ3), the difference in light scattering can be reduced and the difference in propagation distance Δld can be reduced. In the present embodiment, the first wavelength λA of the wavelength λ1 of 800 nm is used, and the wavelength λ3 that _satisfies the light absorption coefficient γμ _aHb ≈ημ _aw in the vicinity of λ = 1200 to 1300 nm is used as the second wavelength λB.

Next, a wavelength selection method will be described. FIG. 12 is a diagram schematically showing the wavelength dependence of the equivalent light absorption coefficient in the vicinity of λ = 1200 to 1300 nm. As can be seen from FIG. 4, the light absorption coefficient γμ _aHb of hemoglobin decreases as the wavelength increases, while the light absorption coefficient ημ _aw of water tends to increase. Here, while sweeping the wavelength, by obtaining the maximum wavelength of the observed diffuse reflection light amount difference ΔRd, the equivalent of (1−ηH−Fw−β) μ _aw and γHμ _aHb in equation (5) The light absorption wavelength λe1 can be obtained. As shown in FIG. 12, the wavelength at which the light absorption coefficient γμ _aHb ≈ημ _aw is considered to be longer than the equivalent light absorption wavelength λe1. Or as _{γ = η, μ aHb ≒ μ} aw become absorbed wavelength λe2 coefficient mu _AHB, may be determined from empirically spectral data relating mu _aw.

  FIG. 13 shows the diffuse reflection light amount difference ΔRd calculated at different detection positions for different H and Fw in the vicinity of the experimentally obtained wavelength of 1300 nm. Although it greatly depends on Fw, it also depends on H, so that the accuracy of the estimated amount of Fw can be improved. FIG. 14 shows a diffuse reflection light amount difference ΔRd with respect to Fw at the detection position (3 mm). Although not clear in FIG. 13, even when H is changed from 0.2 to 0.6, the change in the diffuse reflection light amount difference ΔRd can be ignored.

When light having a wavelength of 1300 nm (λ3) is used, that is, when light having a wavelength of 1300 nm is used as light of the second wavelength λB, ΔRd (λ3, _d3 ) measured as β, μ _aw (λ3), Δl _d3 ) To eliminate the influence of H, and Fw can be estimated from the following equation.

From the above, when light having a wavelength (λB) in the vicinity of a wavelength of 800 nm (λ1 (λA)) and a wavelength of 1300 nm (λ3) is used, Fw is estimated from the above equation (12) to obtain γ, μ _aHb (γ1 ), Δl _d1 and the measured ΔRd (λ1, d), the true H (Hct) excluding the influence of the tissue moisture ratio Fw can be estimated by the following equation (13). In the equation (13), α is an H conversion coefficient of Fw.

In actual measurement, a calibration curve (linear form) shown in FIGS. 9 and 14 is obtained in advance using a standard sample or blood that causes pseudo light scattering in a living body, and then ΔRd at two wavelengths is measured. Thus, a true hematocrit value H (Hct) is estimated. In order to increase the accuracy, the parameter value may be adjusted by the measured hematocrit value H ₀ by blood collection at the time of starting measurement.

As described above, the present embodiment has two wavelengths, λA, which exhibit major absorption in hemoglobin, and wavelengths λB, which exhibit the same light absorption coefficient μ _{aHb ≈μ aw} (γμ _aHb ≈ημ _aw ) between hemoglobin and water. By measuring the variation of the diffuse reflected light amount ΔRd using light, it is possible to estimate the true hematocrit value H (Hct) excluding the influence of the tissue moisture ratio Fw based on a calibration curve prepared in advance.

[Extension of the embodiment]
As described above, the present embodiment has been described with reference to the embodiment, but the present embodiment is not limited to the above-described embodiment. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present embodiment within the scope of the technical idea of the present embodiment.

  DESCRIPTION OF SYMBOLS 1 (1-1) ... 1st light source, 1 (1-2) ... 2nd light source, 2 ... Photodetector, 3 ... Hematocrit value calculation process part, 10 ... Hematocrit value measuring device, 31 ... 1st Diffuse / reflected light amount fluctuation observation unit, 32... Second diffuse / reflected light quantity fluctuation observation unit, 33 ... Hematocrit value calculation unit, 34 ... Tissue moisture ratio calculation unit, 35 ... Hematic value estimation unit, 301 ... Blood vessel, 302 ... Skin, 303 ... living tissue.

Claims (6)

In a hematocrit value measuring device that measures a volume ratio of red blood cells in blood flowing through a blood vessel as a hematocrit value,
A first light source that irradiates a living tissue including the blood vessel with light having a first wavelength;
A second light source that irradiates the biological tissue including the blood vessel with light having a second wavelength different from the first wavelength;
A light detector that detects the amount of light of the first wavelength and the light of the second wavelength that is diffused and propagated in the living tissue and emitted to the outside as a diffuse reflected light amount;
One of the light of the first wavelength and the light of the second wavelength is light having a wavelength exhibiting an equal light absorption coefficient between hemoglobin and water. The hematocrit value measuring apparatus, In the hematocrit value measuring device according to claim 1,
The light of the first wavelength is light having a wavelength that exhibits major absorption in hemoglobin,
The hematocrit value measuring apparatus, wherein the light of the second wavelength is light of a wavelength exhibiting an equal light absorption coefficient between hemoglobin and water. In the hematocrit value measuring device according to claim 1 or 2,
First diffuse reflected light amount fluctuation observation means for observing fluctuations in the diffuse reflected light amount of the light of the first wavelength when the blood vessel is expanded and contracted;
Second diffuse reflected light amount fluctuation observation means for observing fluctuations in the diffuse reflected light amount of the light of the second wavelength when the blood vessel is expanded and contracted;
Hematocrit value calculating means for calculating a hematocrit value of the blood flowing through the blood vessel based on fluctuations in the diffuse reflected light quantity of the light of the first wavelength observed by the first diffuse reflected light quantity fluctuation observation means;
Tissue moisture ratio that calculates the ratio of the amount of moisture contained in the living tissue as the tissue moisture ratio from the variation in the amount of diffusely reflected light of the second wavelength light observed by the second diffusely reflected light amount variation observation means A calculation means;
By correcting the hematocrit value calculated by the hematocrit value calculating means using the tissue moisture ratio calculated by the tissue moisture ratio calculating means, a true hematocrit value that eliminates the influence of the amount of water contained in the living tissue is obtained. A hematocrit value measuring device comprising: a hematocrit value estimating means for estimating. In a hematocrit value measuring method for measuring a volume ratio of red blood cells in blood flowing through a blood vessel as a hematocrit value,
A first step of irradiating the biological tissue including the blood vessel with light having a first wavelength;
A second step of irradiating the biological tissue including the blood vessel with light having a second wavelength different from the first wavelength;
A third step of detecting the amount of light of the first wavelength and the second wavelength of light diffused and propagated in the living tissue and emitted to the outside as a diffuse reflected light amount,
One of the light having the first wavelength and the light having the second wavelength is light having a wavelength exhibiting an equal light absorption coefficient between hemoglobin and water. The method of measuring a hematocrit value, wherein: In the hematocrit value measuring method according to claim 4,
The light of the first wavelength is light having a wavelength that exhibits major absorption in hemoglobin,
The hematocrit value measuring method, wherein the light of the second wavelength is light of a wavelength exhibiting an equal light absorption coefficient between hemoglobin and water. In the hematocrit value measuring method according to claim 4 or 5,
A fourth step of observing fluctuations in the amount of diffusely reflected light of the light having the first wavelength during expansion and contraction of the blood vessel;
A fifth step of observing fluctuations in the amount of diffusely reflected light of the light of the second wavelength during expansion and contraction of the blood vessel;
A sixth step of calculating a hematocrit value of the blood flowing through the blood vessel from a variation in the amount of diffusely reflected light of the light of the first wavelength observed in the fourth step;
A seventh step of calculating, as a tissue moisture ratio, a ratio of the amount of water contained in the living tissue from a variation in the amount of diffusely reflected light of the second wavelength light observed in the fifth step;
A first hematocrit value that eliminates the influence of the amount of water contained in the living tissue is estimated by correcting the hematocrit value calculated in the sixth step using the tissue moisture ratio calculated in the seventh step. A hematocrit value measuring method comprising: 8 steps.