Blood purification device

Abstract

To provide a blood purification device capable of accurately acquiring oxygen saturation without regard to a difference in blood concentration.SOLUTION: The blood purification device comprises a first irradiation part 8, a second irradiation part 8, a third irradiation part 10, a light receiving part 11, and an error absorption part 12 which acquires oxygen saturation from the ratio (R / IR) between first light receiving intensity (R_660) and second light receiving intensity (IR_880) and absorbs an error of the oxygen saturation generated with variation in blood concentration (hematocrit value) based on a third light receiving intensity (IR_810) detected by the light receiving part 11.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a blood purification device that extracorporeally circulates a patient's blood through a blood purifier and a blood circuit to purify the blood.

Background Art

[0002] A hemodialysis device for performing dialysis treatment usually has a blood circuit having an arterial blood circuit and a venous blood circuit for extracorporeally circulating a patient's blood, a dialyzer as a blood purifier connected to the arterial blood circuit and the venous blood circuit respectively to purify the extracorporeally circulating blood, and a water removal pump capable of removing excess water in the blood flowing through the dialyzer for water removal. Blood purification treatment is enabled while removing water from the blood extracorporeally circulated in the blood circuit.

[0003] Conventionally, as disclosed in Patent Document 1 for example, a blood purification device capable of measuring the oxygen saturation of a patient's blood during blood purification treatment has been proposed. Such a conventional blood purification device irradiates first light having a wavelength easily absorbed by oxyhemoglobin in the blood and second light having a wavelength easily absorbed by reduced hemoglobin in the blood from a light emitting unit respectively, and receives the reflected light by a light receiving unit to detect the received light intensity, thereby making it possible to measure the oxygen saturation of the blood.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the conventional blood purification device described above, when measuring blood oxygen saturation, the light-receiving voltage detected by the light-receiving unit changes in accordance with changes in the patient's blood concentration, such as hematocrit, which could lead to errors in the acquired oxygen saturation.

[0006] This invention has been made in view of these circumstances, and its purpose is to provide a blood purification device that can accurately obtain oxygen saturation regardless of differences in blood concentration. [Means for solving the problem]

[0007] A blood purification device according to one embodiment of the present invention is a blood purification device that purifies a patient's blood by circulating the patient's blood extracorporeally through a blood purifier and a blood circuit, comprising: a first irradiation unit that irradiates the blood flowing through the blood circuit with red light; a second irradiation unit that irradiates the blood flowing through the blood circuit with near-infrared light; a third irradiation unit that irradiates the blood flowing through the blood circuit with detection light of a different wavelength from the red light and near-infrared light irradiated from the first and second irradiation units, capable of detecting the blood concentration regardless of the oxygen saturation of the blood; and a receiving unit that receives reflected light or transmitted light of the red light irradiated from the first irradiation unit that has been reflected by the blood or transmitted light that has been passed through the blood. The device comprises a light receiving unit that detects a first light reception intensity obtained by emitting light, a second light reception intensity obtained by receiving reflected light or transmitted light obtained by receiving near-infrared light emitted from the second irradiation unit that has reflected the blood or passed through the blood, and a third light reception intensity obtained by receiving reflected light or transmitted light obtained by receiving detection light emitted from the third irradiation unit that has reflected the blood or passed through the blood, and an error absorption unit that obtains the oxygen saturation from the ratio of the first light reception intensity and the second light reception intensity, and absorbs errors in the oxygen saturation that occur due to changes in the blood concentration based on the third light reception intensity detected by the light receiving unit. Furthermore, the error absorption unit includes: a calibration curve storage unit that stores in advance a calibration curve for determining the oxygen saturation of the blood from the ratio of the first light reception intensity and the second light reception intensity; a ratio correction unit that corrects the ratio of the first light reception intensity and the second light reception intensity detected by the light reception unit based on the third light reception intensity detected by the light reception unit; and an oxygen saturation acquisition unit that acquires the oxygen saturation of the blood from the ratio of the first light reception intensity and the second light reception intensity corrected by the ratio correction unit based on the calibration curve stored in the calibration curve storage unit. It is. [Effects of the Invention]

[0008] According to the present invention, the error in oxygen saturation caused by changes in blood concentration is absorbed based on the third light reception intensity detected by the light receiving unit, so that oxygen saturation can be obtained with high accuracy regardless of differences in blood concentration. [Brief explanation of the drawing]

[0009] [Figure 1] A schematic diagram showing a blood purification device according to the first embodiment of the present invention. [Figure 2] Front view showing the hematocrit sensor in the blood purification device. [Figure 3] Cross-sectional view along line III-III in Figure 2 [Figure 4] Cross-sectional view of line IV-IV in Figure 2 [Figure 5] This graph shows the test results for obtaining a correction coefficient to correct the calibration curve in the blood purification device. [Figure 6] This graph shows the calibration curve applied to the blood purification device. [Figure 7] A flowchart showing the process of obtaining oxygen saturation in the blood purification device. [Figure 8] A schematic diagram showing a blood purification device according to a second embodiment of the present invention. [Figure 9] A flowchart showing the process of obtaining oxygen saturation in the blood purification device. [Figure 10] A schematic diagram showing a blood purification device according to a third embodiment of the present invention. [Figure 11] This graph shows the calibration curve applied to the blood purification device. [Figure 12] A flowchart showing the process of obtaining oxygen saturation in the blood purification device. [Figure 13] A schematic diagram showing a blood purification device according to the fourth embodiment of the present invention. [Figure 14] A flowchart showing the process of obtaining oxygen saturation in the blood purification device. [Modes for carrying out the invention]

[0010] Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. The blood purification device according to the first embodiment is composed of a dialysis device for performing dialysis treatment. As shown in FIG. 1, it includes a blood circuit composed of an arterial side blood circuit 1 and a venous side blood circuit 2, a dialyzer 3 (blood purifier) interposed between the arterial side blood circuit 1 and the venous side blood circuit 2 for purifying the blood flowing through the blood circuit, a blood pump 4, an air trap chamber 5 disposed in the venous side blood circuit 2, a dialysis device main body 6 for supplying dialysis fluid to and discharging drainage from the dialyzer 3, and a blood index detector 7.

[0011] At the tip of the arterial side blood circuit 1, an arterial side puncture needle a can be connected via a connector, and a squeezing type blood pump 4 is disposed in the middle. At the tip of the venous side blood circuit 2, a venous side puncture needle b can be connected via a connector, and an air trap chamber 5 is connected in the middle. An air layer is formed in the air trap chamber 5, and it is configured to capture air bubbles in the liquid.

[0012] The blood pump 4 is composed of a squeezing type pump disposed in the arterial side blood circuit 1 and can make the liquid in the blood circuit flow in the driving direction. That is, a squeezing tube (a part of the arterial side blood circuit 1) that is softer and has a larger diameter than other flexible tubes constituting the arterial side blood circuit 1 is connected to the arterial side blood circuit 1, and rollers for squeezing this squeezing tube in the liquid feeding direction are disposed on the blood pump 4. When the blood pump 4 is driven, the rollers rotate to squeeze the squeezing tube in the liquid feeding direction, and the internal liquid can be made to flow in the driving direction (the rotation direction of the rollers).

[0013] When the blood pump 4 is driven with the arterial side puncture needle a and the venous side puncture needle b puncturing the patient, the patient's blood reaches the dialyzer 3 through the arterial side blood circuit 1, and then is purified by the dialyzer 3. While defoaming is performed in the air trap chamber 5, it returns to the patient's body through the venous side blood circuit 2. That is, the patient's blood is purified by the dialyzer 3 while being extracorporeally circulated from the tip of the arterial side blood circuit 1 to the tip of the venous side blood circuit 2 of the blood circuit.

[0014] The dialyzer 3 has a blood introduction port 3a, a blood outlet port 3b, a dialysate introduction port 3c, and a dialysate outlet port 3d formed in its housing portion. Among these, the arterial side blood circuit 1 is connected to the blood introduction port 3a, and the venous side blood circuit 2 is connected to the blood outlet port 3b, respectively. Further, the dialysate introduction port 3c and the dialysate outlet port 3d are respectively connected to a dialysate introduction line L1 and a dialysate discharge line L2 extending from the dialyzer main body 6.

[0015] A plurality of hollow fiber membranes are housed in the dialyzer 3. The inside of such hollow fiber membranes is used as a blood flow path, and the space between the outer peripheral surface of the hollow fiber membranes and the inner peripheral surface of the housing portion of the dialyzer 3 is used as a dialysate flow path. A large number of minute holes (pores) penetrating the outer and inner peripheral surfaces are formed in the hollow fiber membranes, and the impurities in the blood can permeate into the dialysate through such hollow fiber membranes, thereby enabling the purification of the blood.

[0016] On the other hand, the dialysis machine body 6 is equipped with a fluid delivery device such as a dual pump that spans the dialysate inlet line L1 and the dialysate outlet line L2, and a water removal pump for removing water from the patient's blood flowing through the dialyzer 3 is provided on a bypass line that bypasses the fluid delivery device. Furthermore, one end of the dialysate inlet line L1 is connected to the dialyzer 3 (dialysissate inlet port 3c), and the other end is connected to a dialysate supply device (not shown) that prepares dialysate of a predetermined concentration. In addition, one end of the dialysate outlet line L2 is connected to the dialyzer 3 (dialysissate outlet port 3d), and the other end is connected to a drainage device (not shown), so that the dialysate supplied from the dialysate supply device passes through the dialysate inlet line L1 to the dialyzer 3, and then is sent to the drainage device through the dialysate outlet line L2.

[0017] Furthermore, a pressure sensor is connected to the air trap chamber 5 via a monitoring tube, allowing for the measurement of the fluid pressure (venous pressure) within the air trap chamber 5. An overflow line extends from the upper part (air layer side) of the air trap chamber 5, with a solenoid valve installed along it. By opening the solenoid valve, the fluid (priming fluid, etc.) flowing through the blood circuit can be overflowed via the overflow line.

[0018] The blood indicator detector 7 is attached to predetermined positions in the arterial blood circuit 1 and the venous blood circuit 2. It irradiates light onto the blood flowing through these circuits and calculates or obtains oxygen saturation, hematocrit value, and rate of change of circulating blood volume (ΔBV) based on the received light voltage obtained by receiving the reflected light. As shown in Figures 2 to 4, it is configured to have a first irradiation unit 8, a second irradiation unit 9, and a third irradiation unit 10, which are made up of light-emitting elements (LEDs), and a light-receiving unit 11, which is made up of a light-receiving element (photodiode).

[0019] Furthermore, the blood indicator detector 7 according to this embodiment includes a main body 7a with fitting grooves 7aa and 7ab into which a part of the blood circuit (flexible tube) can be fitted, a lid 7b that can be opened and closed relative to the main body 7a and, when closed, can clamp a part of the blood circuit fitted into the fitting grooves 7aa and 7ab, and a detection switch g that detects the open / closed state of the lid 7b. For example, a flexible tube constituting the arterial blood circuit 1 can be fitted into the fitting groove 7aa and a flexible tube constituting the venous blood circuit 2 can be fitted into the fitting groove 7ab. However, in this embodiment, the flexible tubes constituting the blood circuit are press-fitted into the fitting grooves 7aa and 7ab, and the flexible tubes are firmly fixed to improve detection accuracy. However, the flexible tubes may be loosely fitted or not fitted at all.

[0020] The lid portion 7b is pivotably attached to the main body portion 7a via a pivot axis M, and can be opened and closed by pivoting around the pivot axis M. It also has a locking portion 7c that can engage with the main body portion 7a when closed, and the flexible tube is securely held in place by the locking portion 7c. When the flexible tubes constituting the arterial blood circuit 1 and the venous blood circuit 2 are fitted into the fitting grooves 7aa and 7ab, respectively, and the lid portion 7b is closed, the flexible tube can be held between the main body portion 7a and the lid portion 7b from above and below.

[0021] The detection switch g consists of a microswitch formed between the fitting grooves 7aa and 7ab in the main body 7a. When the lid 7b swings around the pivot axis M and approaches the main body 7a, the switch is pressed by a protrusion 7ba formed on the lid 7b, causing it to turn on. The open / closed state of the lid 7b can be detected by turning the detection switch g on and off.

[0022] Furthermore, slits α and β are formed in the fitting grooves 7aa and 7ab of the main body 7a, respectively. These slits α and β consist of notches formed on the bottom surface of the fitting grooves 7aa and 7ab, and are formed over a predetermined length in the extending direction of the fitting grooves 7aa and 7ab. A printed circuit board K is disposed inside the main body 7a, with the first irradiation unit 8, second irradiation unit 9, third irradiation unit 10 and light receiving unit 11 positioned inside slit α, and the third irradiation unit 10 and light receiving unit 11 positioned inside slit β. These slits α and β can suppress ambient light from the outside of the main body 7a to the light receiving unit 11, and can also improve the linearity of the light irradiated from the first irradiation unit 8, second irradiation unit 9 and third irradiation unit 10. Note that slits α and β may not be formed.

[0023] The light emitted from the first irradiation unit 8, the second irradiation unit 9, and the third irradiation unit 10 is reflected by the blood flowing through the slit α in the arterial blood circuit, and the light emitted from the third irradiation unit 10 is reflected by the blood flowing through the slit β in the venous blood circuit 2, and the light is received by the light receiving unit 11 (configuration of a reflective sensor). In this embodiment, the blood indicator detector 7 is a reflective sensor, but a transmissive sensor that can transmit light through the blood flowing in the blood circuit and receive it may also be used.

[0024] However, the fitting grooves 7aa and 7ab extend from one end edge (right edge in Figure 2) to the other end edge (left edge in Figure 2) of the main body 7a, and the light-receiving section 11 is positioned in the center of the fitting grooves 7aa and 7ab. Furthermore, the first irradiating section 8, the second irradiating section 9, the third irradiating section 10 and the light-receiving section 11 are arranged in a straight line on a single printed circuit board K disposed within the main body 7a, and the light-receiving section 11 is located between the first irradiating section 8, the second irradiating section 9 and the third irradiating section 10 (specifically, between the pair of third irradiating sections 10). In other words, in the slit α, a pair of third irradiating sections 10 are arranged on both sides of the light-receiving section 11, and the first irradiating section 8 and the second irradiating section 9 are arranged further outside of them. In this way, by arranging the light-receiving unit 11 between the light-emitting units (first irradiation unit 8, second irradiation unit 9, and third irradiation unit 10), the influence of ambient light can be minimized.

[0025] Furthermore, a light-absorbing section 7bb is formed on the lid portion 7b at a position facing the first irradiation section 8, the second irradiation section 9, the third irradiation section 10, and the light-receiving section 11, which absorbs the light irradiated from the first irradiation section 8, the second irradiation section 9, and the third irradiation section 10. This light-absorbing section 7bb may be made of a dark color such as black to absorb light, or of a light-absorbing material, etc. As a result, the reflected light irradiated from the first irradiation section 8, the second irradiation section 9, and the third irradiation section 10 and reflected from the blood is received by the light-receiving section 11, while the transmitted light that passes through the blood is absorbed by the light-absorbing section 7bb and does not reach the light-receiving section 11.

[0026] The first irradiation unit 8 consists of an LED (red light LED) capable of irradiating the blood flowing through the blood circuit with red light (red light with a wavelength of 660 nm ± 20 nm), and the second irradiation unit 9 consists of an LED (near-infrared light LED) capable of irradiating the blood flowing through the blood circuit with near-infrared light (near-infrared light with a wavelength of 880 nm (+15 nm, -5 nm)). In other words, the red light irradiated by the first irradiation unit 8 has a wavelength (wavelength of 660 nm) that has the characteristic of having a higher absorbance for deoxyhemoglobin (Hb) than for oxyhemoglobin (HbO2) contained in the blood, and the near-infrared light irradiated by the second irradiation unit 9 has a wavelength (wavelength of 880 nm) that has the characteristic of having a higher absorbance for oxyhemoglobin than for deoxyhemoglobin contained in the blood.

[0027] The third irradiation unit 10 consists of an LED (near-infrared LED) that can irradiate the blood flowing through the blood circuit with detection light (isoabsorpt wavelength) that has a different wavelength from the red light and near-infrared light irradiated from the first irradiation unit 8 and the second irradiation unit 9 (near-infrared light with a wavelength of 810 nm ± 10 nm) and is capable of detecting blood concentration (hematocrit value) regardless of the oxygen saturation of the blood. In other words, the detection light irradiated by the third irradiation unit 10 has a wavelength (wavelength of 810 nm ± 10 nm) that has the characteristic that the absorbance for oxyhemoglobin (HbO2) contained in the blood and the absorbance for deoxyhemoglobin (Hb) are approximately equal.

[0028] The light-receiving unit 11 consists of a photodiode formed on the printed circuit board K together with the first irradiation unit 8, the second irradiation unit 9, and the third irradiation unit 10, and is capable of detecting a first light-receiving intensity (R_660) obtained by receiving reflected light (or transmitted light that has passed through the blood) from red light irradiated from the first irradiation unit 8 that has reflected off the blood, a second light-receiving intensity (IR_880) obtained by receiving reflected light (or transmitted light that has passed through the blood) from near-infrared light irradiated from the second irradiation unit 9, and a third light-receiving intensity (IR_810) obtained by receiving reflected light (or transmitted light that has passed through the blood) from detection light irradiated from the third irradiation unit 10. Incidentally, when receiving transmitted light that has passed through the blood, it is necessary to place a sensor that receives the transmitted light in the light-absorbing part 7bb of the lid 7b. The first light reception intensity (R_660), the second light reception intensity (IR_880), and the third light reception intensity (IR_810) are each detected as voltages (received voltages).

[0029] Here, the dialysis machine body 6 according to this embodiment comprises an error absorption unit 12 having a calibration curve memory unit 13, a ratio correction unit 14, and an oxygen saturation acquisition unit 15, a hematocrit value acquisition unit 16, and a BV calculation unit 17. The error absorption unit 12 consists of, for example, a microcontroller and storage, which are electrically connected to the blood index detector 7, and acquires oxygen saturation (SO2(ABL)%) from the ratio (R / IR) of the first light reception intensity (R_660) and the second light reception intensity (IR_880), and absorbs errors in oxygen saturation that occur with changes in blood concentration (hematocrit value) based on the third light reception intensity (IR_810) detected by the light receiving unit 11.

[0030] The calibration curve memory unit 13 pre-stores a calibration curve C for determining blood oxygen saturation from the ratio (R / IR) of the first light reception intensity (R_660) and the second light reception intensity (IR_880). As shown in Figure 6, calibration curve C consists of a curve (cubic curve) on the horizontal axis representing the ratio (R / IR) of the first light reception intensity (R_660) and the second light reception intensity (IR_880), and on the vertical axis representing oxygen saturation. It is created based on values ​​obtained from experiments conducted in advance, as described later.

[0031] The ratio correction unit 14 corrects the ratio (R / IR) of the first light reception intensity (R_660) and the second light reception intensity (IR_880) detected by the light reception unit 11, based on the third light reception intensity (IR_810) detected by the light reception unit 11. This correction can be performed using a correction coefficient obtained from experiments conducted in advance, as described later.

[0032] In the experiments conducted beforehand, for example, blood samples with different blood concentrations (hematocrit values) (in this experiment, blood samples with hematocrit values ​​(Ht) of 20% and 40%) are irradiated with detection light from the third irradiation unit 10 to obtain the blood concentration (hematocrit value), and red light and near-infrared light are irradiated from the first irradiation unit 8 and the second irradiation unit 9 to obtain the first received light intensity (R_660) and the second received light intensity (IR_880), thereby obtaining multiple straight lines as shown in Figure 5.

[0033] Then, we find the average line of these multiple lines (approximate line y=ax+b). In this case, if we let XHt20 be the received voltage ratio (R / IR) when the hematocrit value (Ht) is 20% and (Ht20) be the hematocrit value calculated at that time, and XHt40 be the received voltage ratio (R / IR) when the hematocrit value (Ht) is 40% and (Ht20) be the hematocrit value calculated at that time, then the values ​​a and b of the approximate line can be found using the following formulas. a=((XHt40 / XHt20)-1) / (Ht40-Ht20)=0.0060 b = XHt40 / XHt20 - a × Ht40 = 0.8967

[0034] Therefore, the correction coefficient K4 based on the hematocrit value (Ht) calculated from the third received light intensity (IR_810) and the corrected received light voltage ratio Xa are as follows, where X is the received light voltage ratio before correction and *Ht is the hematocrit value calculated from the third received light intensity (IR_810). However, *Ht requires zero-span adjustment using a regulator. K4 = 0.0060 × *Ht + 0.8967 Xa = X / K4

[0035] As a result, based on the relationship between the corrected light-receiving voltage ratio Xa and oxygen saturation, a calibration curve C stored in the calibration curve storage unit 13 can be determined, as shown in Figure 6, and a correction coefficient K4 for correcting the light-receiving voltage ratio (R / IR) can be obtained in the ratio correction unit 14. In other words, based on the third light-receiving intensity (IR_810) obtained by irradiating from the third irradiation unit 10 with a wavelength (810 nm wavelength) that has the same absorbance as oxyhemoglobin (HbO2) and deoxyhemoglobin (Hb), a hematocrit value can be obtained while suppressing the influence of oxygen saturation, and the correction coefficient K4 and calibration curve C can be determined using the obtained hematocrit value.

[0036] The oxygen saturation acquisition unit 15 acquires the oxygen saturation of the blood from the ratio (R / IR) of the first and second light reception intensities, which has been corrected by the correction coefficient K4 in the ratio correction unit 14, based on the calibration curve C stored in the calibration curve memory unit 13. The oxygen saturation acquired by the oxygen saturation acquisition unit 15 can be acquired with high accuracy because, even if the hematocrit value changes during blood purification therapy, the error in oxygen saturation that occurs due to the change in the hematocrit value is absorbed.

[0037] The hematocrit value acquisition unit 16 acquires the hematocrit value (Ht) based on the third light reception intensity (IR_810) detected by the light receiving unit 11. In other words, each component that makes up blood, such as red blood cells and plasma, has its own unique absorption characteristics, and by utilizing this property to electro-optically quantify the red blood cells necessary for measuring the hematocrit value, the hematocrit value (Ht) can be determined. Specifically, near-infrared light irradiated from the third irradiation unit 10 is affected by absorption and scattering when reflected by the blood, and is received by the light receiving unit 11. The absorption and scattering rate of the light is analyzed from the intensity of the received light, and the hematocrit value (Ht) is acquired.

[0038] The BV calculation unit 17 calculates the rate of change in circulating blood volume (ΔBV) based on the hematocrit value (Ht) obtained by the hematocrit value acquisition unit 16. That is, the BV calculation unit 17 uses the hematocrit value (Ht) obtained by the hematocrit value acquisition unit 16 to calculate ΔBV(%) = (Ht0 / Ht t The calculation formula is -1) × 100 (where Ht0 is the hematocrit value at the beginning of treatment, Ht t The rate of change in circulating blood volume (ΔBV) is determined from the hematocrit value at the time of measurement, and this rate of change in circulating blood volume (ΔBV) is used as a guideline for the rate and amount of fluid removal. In this way, the drive of the fluid removal pump is controlled based on the acquired hematocrit value, or the rate of change in circulating blood volume ΔBV calculated from that hematocrit value, so that the rate and amount of fluid removal can be adjusted to suit the patient's condition.

[0039] Next, the oxygen saturation calculation process according to this embodiment will be explained based on the flowchart in Figure 7. Calibration curve C is stored in the calibration curve memory unit 13 in advance, and the patient's blood is circulated extracorporeally in the blood circuit. Then, the reflected light of the detection light irradiated from the third irradiation unit 10 is received by the light receiving unit 11, and the third light reception intensity (IR_810) is obtained (S1), and a correction coefficient K4 is calculated from the obtained third light reception intensity (IR_810) (S2).

[0040] Subsequently, red light and near-infrared light are irradiated from the first irradiation unit 8 and the second irradiation unit 9, and the first light reception intensity (R_660) and the second light reception intensity (IR_880) are obtained by the light receiving unit 11 (S3), and the ratio of the first light reception intensity (R_660) and the second light reception intensity (IR_880) (R / IR) is calculated (S4). Based on the correction coefficient K4 obtained in S2, the ratio correction unit 14 corrects the ratio (R / IR) (S5), and the oxygen saturation acquisition unit 15 obtains the oxygen saturation using the corrected ratio (R / IR) and the calibration curve C stored in the calibration curve storage unit 13 (S6).

[0041] According to this embodiment, the error absorption unit 12 includes a calibration curve storage unit 13 that pre-stores a calibration curve C for determining the oxygen saturation of blood from the ratio (R / IR) of the first light reception intensity (R_660) and the second light reception intensity (IR_880), a ratio correction unit 14 that corrects the ratio (R / IR) of the first light reception intensity (R_660) and the second light reception intensity (IR_880) detected by the light receiving unit 11 based on the third light reception intensity (IR_810) detected by the light receiving unit 11, and an oxygen saturation acquisition unit 15 that acquires the oxygen saturation of blood from the ratio (R / IR) of the first light reception intensity (R_660) and the second light reception intensity (IR_880) corrected by the ratio correction unit 14 based on the calibration curve C stored in the calibration curve storage unit 13. Therefore, oxygen saturation can be acquired without changing the calibration curve C stored in the calibration curve storage unit 13.

[0042] Next, a blood purification device according to a second embodiment of the present invention will be described. Components similar to those in the previous embodiment will be denoted by the same reference numerals, and their detailed descriptions will be omitted. The blood circuit according to this embodiment consists of a dialysis machine for performing dialysis treatment, and as shown in Figure 8, it comprises a blood circuit consisting of an arterial blood circuit 1 and a venous blood circuit 2, a dialyzer 3 (blood purifier) ​​interposed between the arterial blood circuit 1 and the venous blood circuit 2 to purify the blood flowing through the blood circuit, a blood pump 4, an air trap chamber 5 disposed in the venous blood circuit 2, a dialysis machine body 6 that supplies dialysate to the dialyzer 3 and discharges drained fluid, and a blood indicator detector 7.

[0043] The dialysis machine body 6 according to this embodiment comprises an error absorption unit 12 having a calibration curve memory unit 13, a calibration curve correction unit 18, and an oxygen saturation acquisition unit 15, a hematocrit value acquisition unit 16, and a BV calculation unit 17. The error absorption unit 12 consists of, for example, a microcontroller and storage, which are electrically connected to the blood index detector 7, and acquires oxygen saturation (SO2(ABL)%) from the ratio (R / IR) of the first light reception intensity (R_660) and the second light reception intensity (IR_880), and absorbs errors in oxygen saturation that occur due to changes in blood concentration (hematocrit value) based on the third light reception intensity (IR_810) detected by the light receiving unit 11.

[0044] The calibration curve correction unit 18 corrects the calibration curve stored in the calibration curve storage unit 13 based on the third light reception intensity (IR_810) detected by the light receiving unit 11. In other words, while the calibration curve C in the first embodiment does not change in response to changes in the hematocrit value, the calibration curve in this embodiment is corrected in real time in response to changes in the hematocrit value.

[0045] The oxygen saturation acquisition unit 15 acquires the oxygen saturation of the blood from the ratio (R / IR) of the first light reception intensity (R_660) and the second light reception intensity (IR_880) detected by the light receiving unit 11, based on the calibration curve corrected by the calibration curve correction unit 18. In other words, the oxygen saturation acquisition unit 15 according to the first embodiment corrects the ratio (R / IR) of the first light reception intensity and the second light reception intensity detected by the light receiving unit 11 with a correction coefficient K4 and determines the oxygen saturation from the corrected ratio (R / IR) and the calibration curve C, whereas the oxygen saturation acquisition unit 15 according to this embodiment determines the oxygen saturation from the ratio (R / IR) of the first light reception intensity and the second light reception intensity detected by the light receiving unit 11 and the calibration curve corrected in real time.

[0046] Next, the oxygen saturation calculation process according to this embodiment will be explained based on the flowchart in Figure 9. A calibration curve (initial calibration curve) is stored in the calibration curve memory unit 13 beforehand, and the patient's blood is circulated extracorporeally in the blood circuit. Then, the reflected light of the detection light irradiated from the third irradiation unit 10 is received by the light receiving unit 11, and the third light reception intensity (IR_810) is obtained (S1), and a correction coefficient is calculated from the obtained third light reception intensity (IR_810) (S2).

[0047] Next, the calibration curve stored in the calibration curve storage unit 13 is corrected using the correction coefficient calculated in S2 (S3), and the first irradiation unit 8 and the second irradiation unit 9 irradiate the device with red light and near-infrared light to obtain the first light reception intensity (R_660) and the second light reception intensity (IR_880) at the light receiving unit 11 (S4), and the ratio of the first light reception intensity (R_660) and the second light reception intensity (IR_880) (R / IR) is calculated (S5). Then, the oxygen saturation is obtained at the oxygen saturation acquisition unit 15 using the calculated ratio (R / IR) and the calibration curve corrected in S3.

[0048] According to this embodiment, the error absorption unit 12 includes a calibration curve storage unit 13 that pre-stores a calibration curve for determining the oxygen saturation of blood from the ratio (R / IR) of the first light reception intensity (R_660) and the second light reception intensity (IR_880), a calibration curve correction unit 18 that corrects the calibration curve stored in the calibration curve storage unit 13 based on the third light reception intensity (IR_810) detected by the light receiving unit 11, and an oxygen saturation acquisition unit 15 that acquires the oxygen saturation of blood from the ratio (R / IR) of the first light reception intensity (R_660) and the second light reception intensity (IR_880) detected by the light receiving unit 11 based on the calibration curve corrected by the calibration curve correction unit 18. Therefore, the oxygen saturation can be acquired without correcting the ratio (R / IR) of the first light reception intensity (R_660) and the second light reception intensity (IR_880) detected by the light receiving unit 11.

[0049] Next, a blood purification device according to a third embodiment of the present invention will be described. Components similar to those in the previous embodiments will be denoted by the same reference numerals, and their detailed descriptions will be omitted. The blood circuit according to this embodiment consists of a dialysis machine for performing dialysis treatment, and as shown in Figure 10, comprises a blood circuit consisting of an arterial blood circuit 1 and a venous blood circuit 2, a dialyzer 3 (blood purifier) ​​interposed between the arterial blood circuit 1 and the venous blood circuit 2 to purify the blood flowing through the blood circuit, a blood pump 4, an air trap chamber 5 disposed in the venous blood circuit 2, a dialysis machine body 6 that supplies dialysate to the dialyzer 3 and discharges drained fluid, and a blood indicator detector 7.

[0050] The dialysis machine body 6 according to this embodiment comprises an error absorption unit 12 having a calibration curve storage unit 13, a calibration curve selection unit 19, and an oxygen saturation acquisition unit 15, a hematocrit value acquisition unit 16, and a BV calculation unit 17. The error absorption unit 12 consists of, for example, a microcontroller and storage, which are electrically connected to the blood index detector 7, and acquires oxygen saturation (SO2(ABL)%) from the ratio (R / IR) of the first light reception intensity (R_660) and the second light reception intensity (IR_880), and absorbs errors in oxygen saturation that occur due to changes in blood concentration (hematocrit value) based on the third light reception intensity (IR_810) detected by the light receiving unit 11.

[0051] The calibration curve memory unit 12 stores a calibration curve for determining blood oxygen saturation from the ratio (R / IR) of the first light reception intensity (R_660) and the second light reception intensity (IR_880). As shown in Figure 11, it stores multiple calibration curves (C1 to C4) corresponding to blood concentration (hematocrit value) in advance. An appropriate number of calibration curves corresponding to blood concentration can be stored in advance.

[0052] The calibration curve selection unit 19 selects a specific calibration curve from among the multiple calibration curves (C1 to C4) stored in the calibration curve storage unit 12 based on the third light reception intensity (IR_810) detected by the light receiving unit 11. In other words, while there is only one calibration curve C in the first and second embodiments, in this embodiment, multiple calibration curves are prepared in advance according to the hematocrit value.

[0053] The oxygen saturation acquisition unit 15 acquires the oxygen saturation of the blood from the ratio (R / IR) of the first light reception intensity (R_660) and the second light reception intensity (IR_880) detected by the light receiving unit 11, based on the calibration curve selected by the calibration curve selection unit 19. In other words, while the oxygen saturation acquisition unit 15 in the first and second embodiments determines oxygen saturation based on a calibration curve that has been corrected in advance or in real time using a correction coefficient, the oxygen saturation acquisition unit 15 in this embodiment determines oxygen saturation using the ratio (R / IR) of the first light reception intensity and the second light reception intensity detected by the light receiving unit 11 and a specific calibration curve selected according to the blood concentration.

[0054] Next, the oxygen saturation calculation process according to this embodiment will be explained based on the flowchart in Figure 12. Multiple calibration curves (C1-C4) corresponding to blood concentration (hematocrit value) are stored in the calibration curve memory unit 13 in advance, and the patient's blood is circulated extracorporeally in the blood circuit. Then, the reflected light of the detection light irradiated from the third irradiation unit 10 is received by the light receiving unit 11, and the third light reception intensity (IR_810) is obtained (S1), and a specific calibration curve corresponding to the hematocrit value is selected from the obtained third light reception intensity (IR_810) (S2).

[0055] Next, red light and near-infrared light are irradiated from the first irradiation unit 8 and the second irradiation unit 9, and the first received light intensity (R_660) and the second received light intensity (IR_880) are obtained by the light receiving unit 11 (S3), and the ratio of the first received light intensity (R_660) and the second received light intensity (IR_880) (R / IR) is calculated (S4). Then, the oxygen saturation is obtained by the oxygen saturation acquisition unit 15 using a specific calibration curve corrected in S2.

[0056] According to this embodiment, the error absorption unit 12 includes a calibration curve storage unit 13 that stores in advance a plurality of calibration curves (C1 to C4) corresponding to blood concentration, which are calibration curves for determining the oxygen saturation of blood from the ratio (R / IR) of the first light reception intensity (R_660) and the second light reception intensity (IR_880), and a calibration curve that selects a specific calibration curve from the plurality of calibration curves (C1 to C4) stored in the calibration curve storage unit 13 based on the third light reception intensity (IR_810) detected by the light receiving unit 11. The system includes a selection unit 19 and an oxygen saturation acquisition unit 15 that acquires the oxygen saturation of the blood from the ratio (R / IR) of the first light reception intensity (R_660) and the second light reception intensity (IR_880) detected by the light receiving unit 11, based on the calibration curve selected by the calibration curve selection unit 19. Therefore, the oxygen saturation can be acquired without correcting the ratio (R / IR) of the first light reception intensity (R_660) and the second light reception intensity (IR_880) detected by the light receiving unit 11, or the calibration curve.

[0057] Next, a blood purification device according to a fourth embodiment of the present invention will be described. Components similar to those in the previous embodiments will be denoted by the same reference numerals, and their detailed descriptions will be omitted. The blood circuit according to this embodiment consists of a dialysis machine for performing dialysis treatment, and as shown in Figure 13, it comprises a blood circuit consisting of an arterial blood circuit 1 and a venous blood circuit 2, a dialyzer 3 (blood purifier) ​​interposed between the arterial blood circuit 1 and the venous blood circuit 2 to purify the blood flowing through the blood circuit, a blood pump 4, an air trap chamber 5 disposed in the venous blood circuit 2, a dialysis machine body 6 that supplies dialysate to the dialyzer 3 and discharges drained fluid, and a blood indicator detector 7.

[0058] The dialysis machine body 6 according to this embodiment comprises an error absorption unit 12 having a calibration curve storage unit 13, a control unit 20, and an oxygen saturation acquisition unit 15, a hematocrit value acquisition unit 16, and a BV calculation unit 17. The error absorption unit 12 consists of, for example, a microcontroller and storage, which are electrically connected to the blood index detector 7, and acquires oxygen saturation (SO2(ABL)%) from the ratio (R / IR) of the first light reception intensity (R_660) and the second light reception intensity (IR_880), and absorbs errors in oxygen saturation that occur due to changes in blood concentration (hematocrit value) based on the third light reception intensity (IR_810) detected by the light receiving unit 11.

[0059] The control unit 20 controls the emission intensity (irradiation intensity) of red light and near-infrared light irradiated by the first irradiation unit 8 and the second irradiation unit 9 based on the third light reception intensity (IR_810) detected by the light receiving unit 11. In other words, when the blood concentration (hematocrit value) changes and the absorbance of the blood changes, the first light reception intensity (R_660) and the second light reception intensity (IR_880) change in correlation with the amount of change, causing an error. To absorb (cancel out) this error, the control unit 20 controls the emission intensity of red light and near-infrared light irradiated by the first irradiation unit 8 and the second irradiation unit 9 according to the third light reception intensity (IR_810), which is correlated with the blood concentration (hematocrit value).

[0060] The oxygen saturation acquisition unit 15 acquires the oxygen saturation of the blood from the ratio (R / IR) of the first light reception intensity (R_660) and the second light reception intensity (IR_880) detected by the light receiving unit 11, based on the calibration curve stored in the calibration curve storage unit 13. In other words, while the oxygen saturation acquisition unit 15 according to the first to third embodiments determines oxygen saturation while maintaining a constant emission intensity of the first irradiation unit 8 and the second irradiation unit 9, the oxygen saturation acquisition unit 15 according to the present embodiment determines oxygen saturation by controlling the emission intensity of the first irradiation unit 8 and the second irradiation unit 9 with the control unit 20 according to the third light reception intensity (IR_810), which is correlated with blood concentration (hematocrit value).

[0061] Next, the oxygen saturation calculation process according to this embodiment will be explained based on the flowchart in Figure 14. A calibration curve is stored in the calibration curve memory unit 13 in advance, and the patient's blood is circulated extracorporeally in the blood circuit. Then, the reflected light of the detection light irradiated from the third irradiation unit 10 is received by the light receiving unit 11, and the third light reception intensity (IR_810) is obtained (S1). Based on the obtained third light reception intensity (IR_810), the emission intensity of the red light and near-infrared light irradiated by the first irradiation unit 8 and the second irradiation unit 9 is controlled (S2).

[0062] Next, red light and near-infrared light are irradiated from the first irradiation unit 8 and the second irradiation unit 9 at the emission intensity controlled in S2, and the first received light intensity (R_660) and the second received light intensity (IR_880) are obtained by the light receiving unit 11 (S3), and the ratio of the first received light intensity (R_660) and the second received light intensity (IR_880) (R / IR) is calculated (S4). Then, the oxygen saturation is obtained by the oxygen saturation acquisition unit 15 using the calculated ratio (R / IR) and the calibration curve stored in the calibration curve storage unit 13.

[0063] According to this embodiment, the error absorption unit 12 includes a calibration curve storage unit 13 that pre-stores a calibration curve for determining the oxygen saturation of blood from the ratio (R / IR) of the first light reception intensity (R_660) and the second light reception intensity (IR_880), a control unit 20 that controls the emission intensity of red light and near-infrared light irradiated by the first irradiation unit 8 and the second irradiation unit 9 based on the third light reception intensity (IR_810) detected by the light receiving unit 11, and an oxygen saturation acquisition unit 15 that acquires the oxygen saturation of blood from the ratio (R / IR) of the first light reception intensity (R_660) and the second light reception intensity (IR_880) based on the calibration curve stored in the calibration curve storage unit 13. Therefore, the oxygen saturation can be acquired without correcting the ratio (R / IR) of the first light reception intensity (R_660) and the second light reception intensity (IR_880) detected by the light receiving unit 11, or the calibration curve.

[0064] According to the blood purification apparatus of the first to fourth embodiments described above, the error in oxygen saturation caused by changes in blood concentration is absorbed based on the third light reception intensity (IR_810) detected by the light receiving unit 11, so that oxygen saturation can be accurately obtained regardless of differences in blood concentration. In particular, since blood concentration (hematocrit value) changes sequentially during the blood purification treatment process, oxygen saturation can be accurately obtained in real time according to the changing blood concentration and reflected in the treatment.

[0065] Furthermore, the red light emitted by the first irradiation unit 8 has a wavelength that is higher in absorbance for deoxyhemoglobin than in oxyhemoglobin contained in the blood, the near-infrared light emitted by the second irradiation unit 9 has a wavelength that is higher in absorbance for oxyhemoglobin than in deoxyhemoglobin contained in the blood, and the detection light emitted by the third irradiation unit 10 has a wavelength that is approximately equal in absorbance for oxyhemoglobin and deoxyhemoglobin contained in the blood, thus enabling the acquisition of oxygen saturation with even greater accuracy.

[0066] Furthermore, the red light emitted by the first irradiation unit 8 has a wavelength of 660 nm, the near-infrared light emitted by the second irradiation unit 9 has a wavelength of 880 nm, and the detection light emitted by the third irradiation unit 10 has a wavelength of 810 nm. Therefore, wavelengths commonly used to determine oxygen saturation are used, and a general-purpose oxygen saturation detector can be applied.

[0067] Furthermore, the device includes a hematocrit value acquisition unit 16 that acquires a hematocrit value based on the third light intensity (IR_810) detected by the light receiving unit 11, and a BV calculation unit 17 that calculates the rate of change of circulating blood volume (ΔBV) based on the hematocrit value acquired by the hematocrit value acquisition unit 16. Therefore, oxygen saturation can be acquired by reusing hematocrit sensors and BV meters that are commonly found in blood purification devices.

[0068] In addition, the blood indicator detector 7 according to this embodiment has a main body 7a to which a first irradiation unit 8, a second irradiation unit 9, a third irradiation unit 10, and a light receiving unit 11 are attached, and which has fitting grooves (7aa, 7ab) formed therein for fitting a part of the blood circuit; a lid 7b which can be opened and closed relative to the main body 7a and can hold a part of the blood circuit fitted into the fitting grooves (7aa, 7ab) when closed; and a light absorbing unit 7bb formed on the lid 7b which absorbs light irradiated from the first irradiation unit 8, the second irradiation unit 9, and the third irradiation unit 10. Therefore, transmitted light that has passed through the blood is absorbed by the light absorbing unit 7bb and reaches the light receiving unit 11, which can suppress the occurrence of errors.

[0069] As described above, the light-absorbing section 7bb can be a dark-colored portion of the lid 7b or a portion made of a light-absorbing material. By having such a configuration, reflection (disturbance) from the lid 7b can be suppressed. Furthermore, the fitting groove extends from one end edge to the other end edge of the main body, and the light-receiving section 11 is positioned in the center of the fitting grooves 7aa and 7ab. This prevents ambient light from reaching the light-receiving section 11 and causing errors. In addition, the first irradiation section 8, the second irradiation section 9, the third irradiation section 10 and the light-receiving section 11 are arranged side by side on the main body 7a, and the light-receiving section 11 is located between the first irradiation section 8, the second irradiation section 9 and the third irradiation section 10. This prevents ambient light, which is a source of errors, from reaching the light-receiving section 11. Furthermore, the first irradiation unit 8, the second irradiation unit 9, the third irradiation unit 10, and the light receiving unit 11 are not limited to being arranged in a straight line, but may be in other layouts, and the light receiving unit 11 may not be located between the first irradiation unit 8, the second irradiation unit 9, and the third irradiation unit 10.

[0070] Although this embodiment has been described above, the present invention is not limited thereto. For example, other wavelengths of light may be used as the red light, near-infrared light, and detection light emitted from the first irradiation unit 8, the second irradiation unit 9, and the third irradiation unit 10. The blood concentration detected by the third light reception intensity (IR_810) is not limited to hematocrit and may be other blood concentrations. Furthermore, the first irradiation unit 8, the second irradiation unit 9, the third irradiation unit 10, and the light receiving unit 11 arranged in the blood indicator detector 7 may be arranged in any layout, and some of them may be arranged in another detector. In this embodiment, the invention is applied to a dialysis machine used during dialysis treatment, but it may also be applied to other devices that can purify the patient's blood while circulating it extracorporeally (for example, hemodiafiltration, hemofiltration, blood purification devices used in AFBF, plasma adsorption devices, etc.). [Industrial applicability]

[0071] The present invention can also be applied to products with different external shapes or those with added functions, provided they are of a similar nature. [Explanation of symbols]

[0072] 1 Arterial blood circuit 2. Venous blood circuit 3. Dialyzer (blood purifier) 4. Blood pump 5. Air trap chamber 6. Dialysis machine main unit 7. Blood indicator detector 7a Main body 7aa, 7ab fitting groove 7b Lid 7ba protrusion 7bb Light-absorbing section 7c Locking part 8 1st irradiation section 9 Second irradiation section 10 Third irradiation section 11 Light receiving section 12 Error absorption section 13 Calibration curve memory unit 14. Ratio Correction Section 15. Oxygen saturation acquisition unit 16. Hematocrit value acquisition unit 17 BV calculation section 18 Calibration curve correction section 19 Calibration curve selection section 20 Control Unit g detection switch K Printed Circuit Board R_660 1st received light intensity IR_880 Second reception intensity IR_810 Third light reception intensity R / IR ratio C, C1~C4 Calibration Curve

Claims

1. A blood purification device that circulates a patient's blood outside the body through a blood purifier and blood circuit, and purifies the blood, A first irradiation unit that irradiates red light onto the blood flowing through the blood circuit, A second irradiation unit that irradiates the blood flowing through the blood circuit with near-infrared light, A third irradiation unit irradiates the blood flowing through the blood circuit with detection light of a different wavelength from the red light and near-infrared light irradiated from the first and second irradiation units, which is capable of detecting the blood concentration regardless of the oxygen saturation of the blood. A light receiving unit that detects a first light reception intensity obtained by receiving reflected light or transmitted light that has passed through the blood from the red light irradiated from the first irradiation unit, a second light reception intensity obtained by receiving reflected light or transmitted light that has passed through the blood from the near-infrared light irradiated from the second irradiation unit, and a third light reception intensity obtained by receiving reflected light or transmitted light that has passed through the blood from the detection light irradiated from the third irradiation unit, The oxygen saturation is obtained from the ratio of the first light reception intensity and the second light reception intensity, and an error absorption unit absorbs the error in the oxygen saturation that occurs due to changes in the blood concentration based on the third light reception intensity detected by the light receiving unit, It comprises, and the error absorption part is A calibration curve storage unit that pre-stores a calibration curve for determining the oxygen saturation of the blood from the ratio of the first light reception intensity and the second light reception intensity, A ratio correction unit corrects the ratio of the first and second light-receiving intensities detected by the light-receiving unit based on the third light-receiving intensity detected by the light-receiving unit, An oxygen saturation acquisition unit acquires the oxygen saturation of the blood from the ratio of the first light reception intensity and the second light reception intensity corrected by the ratio correction unit, based on the calibration curve stored in the calibration curve storage unit. A blood purification device having the following features.

2. The blood purification apparatus according to claim 1, wherein the red light irradiated by the first irradiation unit has a wavelength such that the absorbance for deoxyhemoglobin is higher than the absorbance for oxyhemoglobin contained in the blood, the near-infrared light irradiated by the second irradiation unit has a wavelength such that the absorbance for oxyhemoglobin is higher than the absorbance for deoxyhemoglobin contained in the blood, and the detection light irradiated by the third irradiation unit has a wavelength such that the absorbance for oxyhemoglobin and the absorbance for deoxyhemoglobin contained in the blood are approximately equal.

3. The blood purification apparatus according to claim 2, wherein the red light irradiated by the first irradiation unit has a wavelength of 660 nm, the near-infrared light irradiated by the second irradiation unit has a wavelength of 880 nm, and the detection light irradiated by the third irradiation unit has a wavelength of 810 nm.

4. A blood purification device according to any one of claims 1 to 3, further comprising a hematocrit value acquisition unit that acquires a hematocrit value based on the third light reception intensity detected by the light receiving unit.

5. The blood purification apparatus according to claim 4, further comprising a BV calculation unit that calculates the rate of change in circulating blood volume (ΔBV) based on the hematocrit value obtained by the hematocrit value acquisition unit.

6. The first irradiation unit, the second irradiation unit, the third irradiation unit and the light receiving unit are attached to a main body portion, and a fitting groove for fitting a part of the blood circuit is formed therein, A lid portion that can be opened and closed relative to the main body portion, and which can hold a portion of the blood circuit fitted into the fitting groove when closed, The lid portion is formed with a light absorbing portion that absorbs light irradiated from the first irradiation portion, the second irradiation portion and the third irradiation portion, A blood purification device according to any one of claims 1 to 5, having the following:

7. The blood purification apparatus according to claim 6, wherein the light-absorbing portion is a dark-colored portion of the lid or a portion made of a light-absorbing material.

8. The blood purification device according to claim 6 or claim 7, wherein the fitting groove extends from one end edge to the other end edge of the main body, and the light receiving unit is disposed at the central position of the fitting groove.

9. The blood purification apparatus according to claim 8, wherein the first irradiation unit, the second irradiation unit, the third irradiation unit and the light receiving unit are arranged side by side in the main body, and the light receiving unit is located between the first irradiation unit, the second irradiation unit and the third irradiation unit.

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