Blood component concentration measuring device

Abstract

Comprising: a four-wavelength light emitting unit that emits four types of wavelength light toward a given part of a living body; a light receiving unit that receives the four types of wavelength light that has passed through the given part of the living body; a light receiving intensity information acquisition unit that acquires the light receiving intensity information of the four wavelengths based on the optical signal received by the light receiving unit; an absorbance time change value acquisition unit (201) that obtains the time change value of the absorbance corresponding to the four wavelengths based on the light receiving intensity information of the four wavelengths; a calibration data table (202) that stores calibration data for a given component in blood obtained from the absorbance time change value; and a component concentration acquisition unit (203) that uses the calibration data in the calibration data table (202) to obtain the concentration of a given component in blood based on the time change value of the absorbance obtained by the absorbance time change value acquisition unit.

Description

Technical Field

[0001] The present invention relates to an apparatus for measuring the concentration of components in blood. Background Art

[0002] Patent Document 1 discloses a glucose concentration quantification apparatus that performs high-precision quantitative analysis of glucose concentration by considering interfering factors. The apparatus includes an arithmetic unit that performs regression analysis of glucose concentration based on signals obtained by detecting near-infrared light transmitted through or diffusely reflected from a biological tissue or body fluid by a detection unit. The arithmetic unit uses, as explanatory variables, continuous spectral signals obtained by continuously measuring each wavelength in at least three adjacent regions of a first wavelength region, a second wavelength region, and a third wavelength region within a wavelength range of 1480 nm to 1880 nm, where the influence of the absorption of the first overtone of molecules that can be observed and the absorption of water is relatively small, and uses the glucose concentration as the target variable for quantification.

[0003] The first wavelength region is 1550 nm to 1650 nm for measuring the absorption of the OH group from glucose molecules, the second wavelength region is 1480 nm to 1550 nm for measuring the absorption of the NH group from biological components, and the third wavelength region is 1650 nm to 1880 nm for measuring the absorption of the CH group from biological components.

[0004] Patent Document 2 discloses a high-precision non-invasive biochemical measurement apparatus that can simultaneously measure information on the attenuation of light with a wide range of wavelengths in the same part of a living body. Specifically, light emitted from four light sources is introduced into four optical fibers via four lenses, combined by a wavelength multiplexing element, and then introduced into a single optical fiber. Further, it is irradiated onto the same point of a biological sample via a lens and detected by a light detector.

[0005] The output current of the light detector is converted into a voltage signal by a current-voltage conversion circuit and then converted into a digital signal by an analog / digital converter. A signal processing device controls a light source drive circuit, calculates the absorbance of the biological sample at each wavelength, and calculates the oxygen saturation, blood flow rate, and glucose concentration in the living body.

[0006] Furthermore, Patent Document 3 discloses an apparatus that can accurately measure the concentration of bilirubin in blood without blood collection. Specifically, it includes a first light emitting unit, a second light emitting unit, a third light emitting unit, and a fourth light emitting unit, and light is emitted from these light emitting units to a measurement site. The first light emitting unit has wavelengths absorbed by reduced hemoglobin, oxyhemoglobin, and bilirubin in blood. The second light emitting device has wavelengths absorbed by at least reduced hemoglobin among reduced hemoglobin, oxyhemoglobin, and bilirubin in blood.

[0007] In addition, the third light-emitting unit has a wavelength that is at least absorbed by oxyhemoglobin among reduced hemoglobin, oxyhemoglobin, and bilirubin in blood. The fourth light-emitting unit has a wavelength that is not absorbed by reduced hemoglobin, oxyhemoglobin, and bilirubin in blood but is only absorbed by water. Further, the device includes: a light-receiving unit that receives light emitted from the above-described light-emitting unit and passing through a measurement site, and converts it into an electrical signal; and a signal generation unit that generates signals corresponding to the transmission amounts of the above-described first light, second light, third light, and fourth light based on the output signal of the light-receiving unit. Moreover, the signal generation unit includes an arithmetic unit that calculates the concentration of bilirubin in blood based on the signals generated at a first time and the signals generated at a second time different from the above-described first time.

[0008] Prior Art Documents

[0009] Patent Documents

[0010] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2010-66280

[0011] Patent Document 2: Japanese Unexamined Patent Application Publication No. 10-216112

[0012] Patent Document 3: Japanese Unexamined Patent Application Publication No. 4-332535 Summary of the Invention

[0013] Problems to be Solved by the Invention

[0014] In the invention of Patent Document 1 above, the light source is near-infrared light, which has the advantage of not requiring a light source that emits light in a wide wavelength range, but accurate measurement in each wavelength region is required.

[0015] In addition, although the invention of Patent Document 2 uses a multivariate analysis method to obtain the glucose concentration, it obtains the oxygen saturation, blood flow rate, and glucose concentration, rather than obtaining only the glucose concentration.

[0016] Furthermore, in the invention of Patent Document 3, a ternary simultaneous linear equation is used to obtain C(Hb): the concentration of Hb (reduced hemoglobin) in blood, C(HbO2): the concentration of HbO2 (oxyhemoglobin) in blood, and C(Bil): the concentration of bilirubin in blood, rather than obtaining one measured target value.

[0017] An object of the present embodiment is to provide a blood component concentration measuring device that can shorten the measurement time and accurately detect the concentration of a given component in blood with high precision.

[0018] Technical Solution for Solving the Problems

[0019] The present embodiment is characterized by including: a four-wavelength light emitting unit that emits four types of wavelength light toward a given part of a living body; a light receiving unit that receives the four types of wavelength light transmitted through the given part of the living body; a light receiving intensity information obtaining unit that obtains the light receiving intensity information of the four wavelengths based on the light signal received by the light receiving unit; an absorbance time change value obtaining unit that obtains the time change value of the absorbance corresponding to the four wavelengths based on the light receiving intensity information of the four wavelengths; a calibration data table that stores calibration data for obtaining a given component in blood based on the absorbance time change value; and a component concentration obtaining unit that obtains the concentration of a given component in blood using the calibration data in the calibration data table and based on the time change value of the absorbance obtained by the absorbance time change value obtaining unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a structural diagram of a blood component concentration measuring device according to an embodiment of the present invention.

[0021] Figure 2 is a structural diagram of a computer part of a blood component concentration measuring device according to an embodiment of the present invention.

[0022] Figure 3 is a structural diagram of a unit stored in an external storage device of a computer part of a blood component concentration measuring device according to an embodiment of the present invention.

[0023] Figure 4 is a diagram showing an example of the content of a calibration data table included in a blood component concentration measuring device according to an embodiment of the present invention.

[0024] Figure 5 is a flowchart showing the operation of a blood component concentration measuring device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] Hereinafter, an embodiment of a blood component concentration measuring device according to the present invention will be described with reference to the drawings. In each figure, the same reference numerals are assigned to the same constituent elements and repeated descriptions are omitted. In Figure 1 a structural diagram of a blood component concentration measuring device according to an embodiment of the present invention is shown. In the present embodiment, as the four-wavelength light emitting unit, four LEDs 11, 12, 13, and 14 are used.

[0026] LEDs 11, 12, 13, and 14 emit different 4-wavelength lights towards the fingertip 15 of a given part of the organism. As the above-mentioned 4 wavelengths, the absorption wavelengths of the components to be measured in the blood, the absorption wavelengths of the components in the blood that affect the components to be measured, the absorption wavelength of water, and the wavelengths that are not affected by the components to be measured, the components in the blood that affect the components to be measured, the above-mentioned water, and other biological components can be selected.

[0027] In this embodiment, as the concentration of the component to be measured, the blood glucose level is measured. Therefore, as the 4 wavelengths, 1620 - 1680 nm can be selected as the absorption wavelength of the sugar, which is the component to be measured in the blood, 1170 - 1230 nm can be selected as the absorption wavelength of lipids, which are the components in the blood that affect the component to be measured, 1420 - 1480 nm can be selected as the absorption wavelength of the above-mentioned water, 1170 - 1230 nm can be selected as an example of the absorption of lipids by the components in the blood that affect the sugar, which is the component to be measured, and 1020 - 1180 nm can be selected as the wavelength that is not affected by the above-mentioned water and other biological components.

[0028] If the above wavelengths are corresponded to LEDs 11, 12, 13, and 14, the wavelength of the light emitted from LED 11 can adopt, for example, 1020 - 1180 nm that is not absorbed by any substance. In addition, the wavelength of the light emitted from LED 12 can adopt, for example, 1170 - 1230 nm that is absorbed by lipids. The wavelength of the light emitted from LED 13 can adopt, for example, 1420 - 1480 nm that is absorbed by water, and the wavelength of the light emitted from LED 14 can adopt, for example, 1620 - 1680 nm that is absorbed by sugar.

[0029] LEDs 11, 12, 13, and 14 are connected to the driver 16 and emit light, for example, driven by the driver 16 that operates under the control of a computer 100 such as a personal computer.

[0030] The light transmitted through the fingertip 15 is received by the sensor (light sensor) 17, which is a light receiving unit. The light receiving unit receives 4-wavelength lights transmitted through the given part of the organism. The sensor 17 is connected to the computer 100, and the light signal detected by the sensor 17 is input into the computer 100.

[0031] In Figure 2 shows the structure of the computer 100 part of the blood glucose measurement device (hereinafter, simply referred to as the blood glucose measurement device), which is the blood component concentration measurement device according to this embodiment. The computer 100 is centered around the CPU 110 and reads programs, data, etc. into the main memory 111 to execute processing. The external storage interface 113, input interface 114, display interface 115, data output interface 116, and data input interface 117 are connected to the CPU 110 via the bus 112.

[0032] An external storage device 123 storing a program and various data for the CPU 110 to read and process as a blood glucose measurement device is connected to the external storage interface 113. An input device 124 such as a keyboard and an indicating device 122 such as a mouse are connected to the input interface 114. A display device 125 such as an LED display is connected to the display interface 115 to display necessary images, characters, etc. The display interface 115 can be a wide range of output device interfaces or an interface for connecting an output device such as a printer to the display device 125.

[0033] The previously described driver 16 is connected to the data output interface 116. A drive control signal is sent from the data output interface 116 to the driver 16 according to drive data from the CPU, and the driver 16 causes the required LEDs in the LEDs 11, 12, 13, 14 to emit light for the required time according to this signal. A sensor 17 is connected to the data input interface 117, and the output signal of the sensor 17 is taken in and AD-converted and sent to the CPU 110 as received light intensity information (data). Therefore, the data input interface 117 functions as a received light intensity information acquisition unit, and this received light intensity information acquisition unit obtains the received light intensity information of the above four wavelengths based on the light signal received by the sensor 17 as the received light unit.

[0034] As described previously, a program and various data for the CPU 110 to read and process as a blood glucose measurement device are stored in the external storage device 123. Specifically, as Figure 3 shown, it includes an absorbance time change value acquisition unit 201 implemented by a program, a calibration data table 202, and a blood glucose value acquisition unit (generally a component concentration acquisition unit) 203 implemented by a program. The absorbance time change value acquisition unit 201 obtains the time change value of the absorbance corresponding to the above four wavelengths based on the above four-wavelength received light intensity information obtained by the data input interface 117 as the received light intensity information acquisition unit.

[0035] The calibration data table 202 stores calibration data for obtaining the blood glucose value based on the absorbance time change value. Specifically, as Figure 4 shown, it is a table in which the numerical values (letters are numerical values) of calibration data a, b, c, d,... are associated with the absorbance time change values A, B, C, D,....

[0036] The calibration data table 202 stores calibration data generated based on blood data initially obtained for a majority of people by the method of the present embodiment and blood glucose values obtained by a known method including an invasive method, and starts. After that, based on the blood glucose values obtained by the method of the present embodiment and the blood glucose values obtained by a known method including an invasive method, the calibration data can be updated by methods such as statistical analysis and machine learning to become highly accurate data.

[0037] The blood glucose value acquisition unit 203 uses the calibration data in the calibration data table 202 described above to calculate the blood glucose value based on the time change value of the absorbance obtained by the absorbance time change value acquisition unit 201. When the absorbance time change value acquisition unit 201 acquires the time change value of the absorbance as, for example, aba, Figure 3 the calibration data value BB is taken out from the calibration data table 202, and a given operation (addition operation, multiplication operation, division operation, etc.) using the calibration data value BB is performed on the acquired time change value aba of the absorbance to calculate the blood glucose value.

[0038] The blood glucose value calculated as described above can be converted into display data by the CPU 110 and sent to the display interface 115. The display interface 115 that receives this data can control the display device 125 to display the blood glucose value on the display device 125.

[0039] The blood glucose value measuring device configured as described above operates according to Figure 5 the flowchart shown, and thus the operation will be described with reference to this flowchart. When the operation starts, the CPU 110 controls the driver 16 to drive the four LEDs 11 to 14 to emit four-wavelength light (S11). Here, the four LEDs 11 to 14 are sequentially driven for a given time, and light of four wavelengths λ1, λ2, λ3, and λ4 is emitted to the fingertip 15 in given time units.

[0040] In the present embodiment, the blood glucose value is calculated using the absorbance at four wavelengths. As a method thereof, statistical analysis represented by multivariate analysis can be used, but the present invention is not limited thereto. For example, machine learning can also be used. As a method based on statistical analysis, for example, consider the following method. Following the above step S11, the light transmitted through the fingertip 15 is received by the sensor 17, and the received light intensity information ai, bi, ci, di is acquired (S12). Based on the received light intensity information ai, bi, ci, di, the time change value of the absorbance corresponding to the four wavelengths, that is, the blood data = η1 + η2 + η3 + η4, is calculated (S13).

[0041] In this embodiment, each wavelength is measured at least once for the pulse. For example, if the wavelengths are switched as λ1nm → λ2nm → λ3nm → λ4nm for measurement, then the measurement points for each of the four wavelengths up to this point become one-point plots. Next, if the wavelengths are switched as λ1nm → λ2nm → λ3nm → λ4nm for measurement, then the measurement points for the four wavelengths up to this point become two-point plots. Next, if the wavelengths are switched as λ1nm → λ2nm → λ3nm → λ4nm for measurement, then the measurement points for the four wavelengths up to this point become three-point plots. The measurement is carried out in the same way hereinafter to obtain plots of a desired number (e.g., 20) of points.

[0042] By connecting the plots of the above-mentioned desired number, it is possible to form a pulse peak at each wavelength λ1, λ2, λ3, λ4. The measurement is carried out until there can be one or more pulse peaks (e.g., whether 50 peaks or 100 peaks, the same number of peaks in each wavelength), and this is taken as a set of time series data. One set of such time series data is obtained before a meal, the next set of time series data is obtained after the meal, and the next set of time series data is obtained at a given time (e.g., 3 hours) after the meal,... In the same way hereinafter, time series data is obtained on a longer time scale.

[0043] When ωλj (j = 1 to 4) is set as the weighting coefficient at wavelength λj, singular value decomposition is used to obtain the intermediate parameters pA, pB, pC, pD in the following formula (1), and the absorbance time change value is obtained based on the obtained intermediate parameters pA, pB, pC, pD.

[0044] [Mathematical formula 1]

[0045]

[0046] The above formula (1) is equivalent to the following formula (2).

[0047] [Mathematical formula 2]

[0048]

[0049] Regarding the intermediate parameters in the above formula (2), the parameter corresponding to the time series data at a certain moment t1 in the time series data described above is the following formula (3),

[0050] [Mathematical formula 3]

[0051]

[0052] In the time series data described above, the parameter corresponding to the time series data measured at a moment t2 after the moment t1 is the following formula (4),

[0053] [Mathematical formula 4]

[0054]

[0055] Regarding t1, t2, ……, for example, the moment t1 corresponds to the moment before a meal, and t2 corresponds to the moment just after a meal, etc.

[0056] Similarly hereinafter, an expression for generating an intermediate parameter can be obtained from a set of time series data.

[0057] Since the detected received light intensity information ai, bi, ci, di contains noise, the pulse can be measured more than once. Moreover, if the measurement is set to be more than twice, the matrix of Equation (1) will not be a diagonal matrix. Therefore, in the present embodiment, singular value decomposition is used to obtain the intermediate parameters pA, pB, pC, pD. The process of repeatedly obtaining the optimal solution in such a way that the values of the intermediate parameters pA, pB, pC, pD become the longest can be performed in every measurement of four times or more. This operation is performed by the absorbance time change value acquisition unit 201.

[0058] Furthermore, when the absorbance time change value is blood data = η1 + η2 + η3 + η4 as blood data, the absorbance time change value acquisition unit 201 sets undetermined multipliers x1, x2, x3, x4, and obtains η1, η2, η3, η4 for the following Equation (5) by the Lagrange undetermined multiplier method.

[0059] [Mathematical formula 5]

[0060]

[0061] If the blood data = η1 + η2 + η3 + η4 is obtained as described above, the blood glucose value is obtained using the calibration data in the calibration data table 202 and output from the display device 125 (S14).

[0062] The obtained blood glucose value and calibration data are fed back to the calibration data table 202, and the accuracy of the calibration data is improved. Since the received light intensity information ai, bi, ci, di is obtained from the optical signal actually transmitted through the fingertip, and the blood glucose value is obtained by calculation using the calibration data, the blood glucose value can be appropriately measured regardless of who measures it, reflecting the magnitude of the absorbance due to the pulse wave component.

[0063] In addition, in the present embodiment, the control of the LED emission, the acquisition of the received light intensity information ai, bi, ci, di after receiving the transmitted light, the acquisition of blood data, and the calculation of the blood glucose value using the calibration data are performed by one computer. However, they may also be performed by different computers or control devices respectively, or several operations may be grouped and distributed among two to three computers. In this case, one computer can also be arranged remotely to acquire blood data and calculate the blood glucose value using the calibration data at multiple locations, and to control the LED emission and acquire the received light intensity information ai, bi, ci, di after receiving the transmitted light. If such a system is adopted, the data of a large number of people can be concentrated on the computer at one location to appropriately update the calibration data.

[0064] In the above embodiment, a blood glucose value measuring device that obtains the blood glucose value as the "concentration of a given component in blood" has been described. However, the present invention is not limited thereto. For example, it is also expected that the blood lipid concentration, blood cholesterol concentration, etc. can be measured.

[0065] In addition, in the above description, the computer 100 is assumed to be a personal computer or the like. However, the blood component concentration measuring device according to the present embodiment may also be a dedicated device, and the computer 100 may be constituted by a dedicated CPU. In this case, the necessary programs and data for processing as a blood glucose value measuring device may also be stored in the main memory 111.

[0066] Furthermore, a determination device for determining normal / abnormal and warning levels based on the results measured by the blood component concentration measuring device according to the present embodiment may also be provided in the network. The results measured by the blood component concentration measuring device according to the present embodiment are sent to the above determination device via the network, and the determination results are returned. Of course, instead of providing a determination device, a storage device for storing the determination results may be provided. A doctor accesses the storage device using the network to make a determination and stores the determination results in the storage device. The blood component concentration measuring device according to the present embodiment takes in the determination results and performs display, etc.

[0067] Symbol Description

[0068] 11 - 14 LEDs

[0069] 15 Fingertip

[0070] 16 Driver

[0071] 17 Sensor

[0072] 100 Computer

[0073] 110 CPU

[0074] 111 Main memory

[0075] 112 Bus

[0076] 113 External storage interface

[0077] 114 Input interface

[0078] 115 Display interface

[0079] 116 Data output interface

[0080] 117 Data input interface

[0081] 122 Indicator device

[0082] 123 External storage device

[0083] 124 Input device

[0084] 125 Display device

[0085] 201 Absorbance time change value acquisition unit

[0086] 202 Calibration data table

[0087] 203 Blood glucose value acquisition unit (component concentration acquisition unit).

Claims

1. A device for measuring the concentration of components in blood, characterized in that, the device for measuring the concentration of components in blood comprises: a 4-wavelength light emitting unit that emits 4 kinds of wavelength light toward a given part of a living body; a light receiving unit that receives the 4 kinds of wavelength light transmitted through the given part of the living body; a light receiving intensity information acquisition unit that obtains the light receiving intensity information of the above 4 wavelengths based on the optical signal received by the light receiving unit; an absorbance time change value acquisition unit that obtains the time change value of the absorbance corresponding to the 4 wavelengths based on the light receiving intensity information of the 4 wavelengths; a calibration data table that stores calibration data for obtaining the component to be measured in blood according to the absorbance time change value; and a component concentration acquisition unit that uses the calibration data in the calibration data table to obtain the concentration of the component to be measured in blood according to the time change value of the absorbance obtained by the absorbance time change value acquisition unit, the 4 wavelengths select 1620 - 1680 nm as the absorption wavelength of the component to be measured in blood, select 1170 - 1230 nm, the absorption wavelength of lipids, as the component in blood that affects the component to be measured, select 1420 - 1480 nm as the absorption wavelength of water, and select 1020 - 1180 nm as the wavelength that is not affected by the component to be measured, the component in blood that affects the component to be measured, the water, and other biological components.

2. The device for measuring the concentration of components in blood according to claim 1, characterized in that, the absorbance time change value acquisition unit obtains the time change value of the absorbance corresponding to the 4 wavelengths based on a plurality of consecutive light receiving intensity information obtained by the light receiving intensity information acquisition unit at a given time interval.

3. The device for measuring the concentration of components in blood according to claim 1 or 2, characterized in that, the absorbance time change value acquisition unit obtains the time change value of the absorbance corresponding to the 4 wavelengths based on the light receiving intensity information obtained continuously one or more times by the light receiving intensity information acquisition unit at a given time interval.

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