JP2013027455A - Blood purification apparatus and calibration method for blood concentration sensor in the blood purification apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blood purification apparatus and a calibration method for the blood concentration sensor in the blood purification apparatus in which at least the inclination of the calibration curve of the blood concentration sensor can be calibrated and measurement error can be prevented.SOLUTION: The calibration method includes the first step in which blood is circulated extracorporeally in a blood circuit without performing water removal and a light receiving voltage is detected to obtain a blood concentration based on respective calibration curves, the second step in which the blood is extracorporeally circulated in the blood circuit with the water removal performed and the light receiving voltage is detected to calculate the theoretical blood concentration, the third step in which the relationship of light receiving voltage and the blood concentration of the vein side blood concentration sensor is obtained to calibrate the calibration curve of the vein side blood concentration sensor based on the relationship concerned, and the fourth step in which the calibration curve of the artery side blood concentration sensor is calibrated, based on the relationship of the calibration curve of the vein side blood concentration sensor calibrated by the third step and the calibration curve of the vein side blood concentration sensor before the calibration.

Description

  The present invention relates to an arterial blood concentration sensor attached to an arterial blood circuit, a blood purification device having a venous blood concentration sensor attached to a venous blood circuit, and a method for calibrating the blood concentration sensor in the blood purification device. Is.

  A hemodialysis apparatus for performing dialysis treatment is normally connected to a blood circuit including an arterial blood circuit and a venous blood circuit for circulating a patient's blood extracorporeally, and an arterial blood circuit and a venous blood circuit, respectively. And a dialyzer as a blood purifier for purifying blood circulating outside the body, and a water removal pump capable of removing water by removing excess water in the blood flowing through the dialyzer. Blood purification treatment is possible while removing the blood to be removed.

  The amount of water to be removed at the time of water removal (water removal speed) is controlled by controlling the drive of the water removal pump. However, if rapid or excessive water removal is performed, the patient's circulating blood volume will be excessive. However, if the rate of water removal is slow, the entire treatment time may be extended and the patient may be burdened. For this reason, for example, by arranging a blood concentration sensor or the like in the arterial blood circuit, the concentration of blood circulating extracorporeally during treatment, in particular, the hematocrit value, which is the volume fraction of blood cells, is measured and monitored sequentially. And safe treatment can be performed.

  A hematocrit sensor for measuring a hematocrit value as such a blood concentration sensor is used. Such a hematocrit sensor, for example, as disclosed in Patent Document 1, irradiates blood such as infrared rays to blood circulating outside the body, and receives the reflected light and the relationship between the received light voltage and the hematocrit value (straight line). Relationship). In such a hematocrit sensor, a calibration curve is usually obtained in advance from the relationship between the received light voltage obtained using typical blood and the hematocrit value, and the hematocrit value at the time of treatment can be measured using such a calibration curve. It is like that.

During the treatment, the hematocrit value is sequentially measured by the hematocrit sensor, and by using the measured hematocrit value, the rate of change of the circulating blood volume (ΔBV) is usually obtained as a measure of the water removal rate. Yes. The rate of change of the circulating blood volume (ΔBV) is an arithmetic expression of ΔBV (%) = (Ht ₀ / Ht _t −1) × 100 (where Ht ₀ is the hematocrit value at the initial stage of treatment, and Ht _t is the measurement time point) (Hematocrit value).

Japanese Patent Application Laid-Open No. 2004-97782

  However, in the above conventional blood concentration sensor (hematocrit sensor), since infrared rays are irradiated and hemoglobin in red blood cells absorbs the infrared rays, the hematocrit value is measured. However, there is a problem that the error becomes large due to the influence of some inhibitory substance other than erythrocytes (mainly an inhibitory substance that affects scattering).

  In addition, since a calibration curve is obtained in advance using representative blood, the calibration curve may be shifted due to the influence of the inhibitor during actual treatment, resulting in a large measurement error. However, in determining the rate of change in the circulating blood volume (ΔBV), which is a measure of the water removal rate, even if a certain amount of error occurs in the measured hematocrit value itself, there will be no problem, but the calibration curve If the slopes are different, the error becomes significantly large.

  Such a defect is not limited to a blood concentration sensor that measures blood concentration based on a light reception voltage obtained by receiving light reflected from blood, but is obtained by receiving light transmitted through blood. This also occurs in the case of measuring blood concentration based on the received light voltage or using light other than infrared light.

  The present invention has been made in view of such circumstances, and at least the inclination of the calibration curve of the blood concentration sensor can be calibrated, and the blood concentration in the blood purification device and the blood purification device capable of suppressing measurement errors. It is to provide a sensor calibration method.

  The invention according to claim 1 is connected to the blood circuit composed of an arterial blood circuit and a venous blood circuit for circulating the patient's blood extracorporeally, and is connected to the arterial blood circuit and the venous blood circuit, respectively. A blood purifier for purifying blood, a water removal means capable of removing water by removing water in the blood flowing through the blood purifier, and attached to the arterial blood circuit and flowing through the arterial blood circuit An arterial blood concentration sensor that can measure a blood concentration based on a light reception voltage obtained by receiving light transmitted or reflected to blood and has a calibration curve obtained in advance from the relationship between the light reception voltage and the blood concentration And a blood concentration can be measured based on a light reception voltage obtained by receiving light transmitted through or reflected from the blood flowing through the vein blood circuit and attached to the vein blood circuit. A blood purification apparatus comprising a venous blood concentration sensor having a calibration curve obtained in advance from the relationship between pressure and blood concentration, wherein the calibration curves of the arterial blood concentration sensor and the venous blood concentration sensor are calibrated The calibration means for circulating the blood extracorporeally in the blood circuit in a state where water removal by the water removal means is not performed, and the arterial blood concentration sensor and the vein blood concentration sensor. A first step of detecting a light reception voltage and obtaining a blood concentration based on a respective calibration curve corresponding to the detected light reception voltage, and in the blood circuit in a state of water removal by the water removal means Blood obtained by extracorporeal circulation, detection of received light voltage by the venous blood concentration sensor, and detection by the venous concentration sensor in the first step A second step of calculating a theoretical blood concentration by calculation using the concentration as a parameter; a light reception voltage and a blood concentration of the venous blood concentration sensor obtained in the first step; Based on the received light-receiving voltage of the vein-side blood concentration sensor and the theoretical blood concentration, the relationship between the light-receiving voltage of the vein-side blood concentration sensor and the blood concentration is obtained, and based on the relationship, the vein-side blood concentration Based on the third step of calibrating the calibration curve of the sensor, and the relationship between the calibration curve of the venous blood concentration sensor calibrated in the third step and the calibration curve of the venous blood concentration sensor before calibration, the arterial blood The fourth step of calibrating the calibration curve of the concentration sensor is performed.

  According to a second aspect of the present invention, in the blood purification apparatus according to the first aspect, the arterial blood concentration sensor and the venous blood concentration sensor are capable of measuring a hematocrit value indicating a blood concentration, and an arterial hematocrit sensor and a venous hematocrit. It consists of a sensor.

According to a third aspect of the present invention, in the blood purification apparatus according to the second aspect, the second step includes: Ht _true = Qb / (Qb−Quf) × Ht _V0 (where Ht _true is a theoretical hematocrit value, Qb The above calculation is performed by the following equation: is the extracorporeal circulation flow rate of blood, Quf is the water removal rate, and Ht _V0 is the hematocrit value obtained in the first step.

  According to a fourth aspect of the present invention, in the blood purification apparatus according to any one of the first to third aspects, the fourth step includes the calibration curve slope of the calibrated vein-side blood concentration sensor and the calibration before calibration. A ratio with the slope of the calibration curve of the venous blood concentration sensor is obtained, and the calibration curve of the arterial blood concentration sensor is calibrated based on the ratio.

  The invention according to claim 5 is the blood purification apparatus according to any one of claims 1 to 4, wherein a peak peculiar to a change in blood concentration is obtained by performing rapid and short-time concentration or dilution of blood. A blood pressure sensor that can be applied, and the arterial blood concentration sensor and the venous blood concentration sensor are capable of detecting a specific peak applied by the peak applying device. Based on the specific peak detected by the venous blood concentration sensor, the blood returned to the patient from the venous blood circuit is again guided to the arterial blood circuit and the recirculated blood flowing can be detected. It is characterized by.

  The invention described in claim 6 is connected to the blood circuit composed of an arterial blood circuit and a venous blood circuit for circulating the patient's blood extracorporeally, and is connected to the arterial blood circuit and the venous blood circuit, respectively. A blood purifier for purifying blood, a water removal means capable of removing water by removing water in the blood flowing through the blood purifier, and attached to the arterial blood circuit and flowing through the arterial blood circuit An arterial blood concentration sensor that can measure a blood concentration based on a light reception voltage obtained by receiving light transmitted or reflected to blood and has a calibration curve obtained in advance from the relationship between the light reception voltage and the blood concentration And a blood concentration can be measured based on a light reception voltage obtained by receiving light transmitted through or reflected from the blood flowing through the vein blood circuit and attached to the vein blood circuit. A method for calibrating a blood concentration sensor in a blood purification apparatus comprising a venous blood concentration sensor having a calibration curve obtained in advance from the relationship between pressure and blood concentration, wherein water removal by the water removal means is not performed In the state, blood is circulated extracorporeally in the blood circuit, and the received light voltage is detected by the arterial blood concentration sensor and the venous blood concentration sensor, and the respective calibration curves corresponding to the detected received light voltages are applied. A first step of obtaining a blood concentration based on the above, circulating the blood extracorporeally in the blood circuit in a state where water removal by the water removal means is performed, detecting a light reception voltage by the vein side blood concentration sensor, and A second step of calculating a theoretical blood concentration by calculation using the blood concentration obtained by detection of the vein-side concentration sensor in the first step as a parameter; Based on the light reception voltage and blood concentration of the venous blood concentration sensor obtained in the step, and the light reception voltage and theoretical blood concentration of the venous blood concentration sensor obtained in the second step, the vein A third step of obtaining a relationship between the light reception voltage of the side blood concentration sensor and the blood concentration, calibrating a calibration curve of the vein side blood concentration sensor based on the relationship, and the venous blood calibrated in the third step The fourth step of calibrating the calibration curve of the arterial blood concentration sensor is performed based on the relationship between the calibration curve of the concentration sensor and the calibration curve of the venous blood concentration sensor before calibration.

  The invention according to claim 7 is the method for calibrating a blood concentration sensor in the blood purification apparatus according to claim 6, wherein the artery side blood concentration sensor and the vein side blood concentration sensor are capable of measuring a hematocrit value indicating the blood concentration. It consists of a side hematocrit sensor and a venous side hematocrit sensor.

The invention according to claim 8 is the method of calibrating a blood concentration sensor in the blood purification apparatus according to claim 7, wherein the second step is Ht _true = Qb / (Qb−Quf) × Ht _V0 (where Ht _true is The above calculation is performed by a calculation formula of a theoretical hematocrit value, Qb is an extracorporeal circulation flow rate of blood, Quf is a water removal rate, and Ht _V0 is a hematocrit value obtained in the first step.

  The invention according to claim 9 is the method for calibrating a blood concentration sensor in the blood purification apparatus according to any one of claims 6 to 8, wherein the fourth step is a calibration of the calibrated vein-side blood concentration sensor. A ratio between the slope of the line and the slope of the calibration curve of the venous blood concentration sensor before calibration is obtained, and the calibration curve of the arterial blood concentration sensor is calibrated based on the ratio.

  A tenth aspect of the present invention is the blood concentration sensor calibration method in the blood purification apparatus according to any one of the sixth to ninth aspects, wherein the blood concentration is obtained by abrupt and short-time concentration or dilution of blood. The arterial blood concentration sensor and the venous blood concentration sensor can detect the unique peak, and the arterial blood concentration sensor and the venous blood concentration sensor. On the basis of the characteristic peak detected in step 1, the blood returned to the patient from the venous side blood circuit is guided to the arterial side blood circuit again, and the recirculated blood flowing can be detected.

  According to the first and sixth aspects of the invention, the calibration curve of at least the arterial blood concentration sensor and the venous blood concentration sensor is calibrated by calibrating the calibration curve based on the actual blood of the patient through the first to fourth steps. The slope of the line can be calibrated and measurement errors can be suppressed.

  According to the inventions of claims 2 and 7, the arterial blood concentration sensor and the venous blood concentration sensor are composed of the arterial hematocrit sensor and the venous hematocrit sensor capable of measuring a hematocrit value indicating the blood concentration. The rate of change (ΔBV) in the circulating blood volume, which is a measure of the above, can be determined easily and accurately.

According to the inventions of claims 3 and 8, the second step is Ht _true = Qb / (Qb−Quf) × Ht _V0 (where Ht _true is the theoretical hematocrit value, Qb is the extracorporeal circulation flow rate of blood, Quf Is the water removal speed and Ht _V0 is the hematocrit value obtained in the first step), so that the calibration curve can be calibrated more accurately.

  According to the inventions of claims 4 and 9, the fourth step calculates a ratio between the slope of the calibration curve of the calibrated vein-side blood concentration sensor and the slope of the calibration curve of the vein-side blood concentration sensor before calibration, Since the calibration curve of the arterial blood concentration sensor is calibrated based on the ratio, the calibration curve of the arterial blood concentration sensor can be calibrated by a simpler calculation.

  According to the fifth and tenth aspects of the present invention, the blood returned from the venous blood circuit to the patient based on the specific peaks detected by the arterial blood concentration sensor and the venous blood concentration sensor is again returned to the arterial blood circuit. Since the recirculated blood that has been guided and can be detected, the recirculated blood can be detected in addition to calibration of the calibration curves of the arterial blood concentration sensor and the venous blood concentration sensor.

1 is an overall schematic view showing a blood purification apparatus according to an embodiment of the present invention. Schematic diagram showing the internal configuration of the dialyzer body in the blood purification apparatus It is an external view which shows the hematocrit sensor in the blood purification apparatus, (a) Top view (b) Front view IV-IV line sectional view in FIG. A graph showing a calibration curve of hematocrit sensors (arterial hematocrit sensor and venous hematocrit sensor) in the blood purification apparatus The graph which shows the state which plotted the received light voltage measured with the hematocrit sensor (arterial side hematocrit sensor and venous side hematocrit sensor) on the calibration curve in the 1st process in the blood purification apparatus. A graph plotting the received light voltage measured by the hematocrit sensor (arterial hematocrit sensor and venous hematocrit sensor) and the calculated theoretical hematocrit value in the second step of the blood purification apparatus. A graph showing the received light voltage measured by the hematocrit sensor (arterial hematocrit sensor and venous hematocrit sensor) and the calibration curve calibrated based on the calculated theoretical hematocrit value in the second step of the blood purification apparatus. Graph showing the specific peak of blood concentration in the blood purification device The graph which shows the change of the hematocrit value detected with the venous hematocrit sensor in the blood purification apparatus The graph which shows the change of the hematocrit value detected with the venous hematocrit sensor in the blood purification apparatus The schematic diagram which shows the internal structure of the dialyzer main body in the blood purification apparatus which concerns on other embodiment of this invention.

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
The blood purification apparatus according to the present embodiment is for purifying a patient's blood while circulating it extracorporeally, and is applied to a dialysis apparatus used in dialysis treatment. As shown in FIG. 1, the dialysis apparatus mainly includes a blood circuit 1 to which a dialyzer 2 as a blood purifier is connected, and a dialysis apparatus main body 6 that removes water while supplying dialysate to the dialyzer 2. . As shown in the figure, the blood circuit 1 is mainly composed of an arterial blood circuit 1a and a venous blood circuit 1b made of a flexible tube. The arterial blood circuit 1a and the venous blood circuit 1b A dialyzer 2 is connected between them.

  An arterial puncture needle a is connected to the tip of the arterial blood circuit 1a, and an iron-type blood pump 3 and an arterial hematocrit sensor 5a (arterial blood concentration sensor) are disposed in the middle. . On the other hand, a venous puncture needle b is connected to the distal end of the venous blood circuit 1b, and a venous hematocrit sensor 5b (venous blood concentration sensor) and a defoaming air trap chamber 4 are connected to the venous blood circuit 1b. Has been.

  When the blood pump 3 is driven with the patient punctured with the arterial puncture needle a and the vein puncture needle b, the blood of the patient collected from the arterial puncture needle a passes through the arterial blood circuit 1a. Then, the blood is purified by the dialyzer 2, defoamed in the air trap chamber 4, passes through the venous blood circuit 1 b, and returns to the patient's body through the venous puncture needle b. That is, the blood of the patient is purified by the dialyzer 2 while circulating outside the body by the blood circuit 1.

  The dialyzer 2 is formed with a blood introduction port 2a, a blood outlet port 2b, a dialysate inlet port 2c, and a dialysate outlet port 2d in the casing. Among these, the blood inlet port 2a has an arterial blood circuit 1a. The base end of the venous blood circuit 1b is connected to the blood outlet port 2b. The dialysate introduction port 2c and the dialysate lead-out port 2d are connected to a dialysate introduction line L1 and a dialysate discharge line L2 extending from the dialyzer body 6, respectively.

  A plurality of hollow fibers are accommodated in the dialyzer 2, the inside of the hollow fibers is used as a blood flow path, and the flow of dialysate is between the hollow fiber outer peripheral surface and the inner peripheral surface of the housing. It is considered a road. A hollow fiber membrane is formed in the hollow fiber by forming a large number of minute holes (pores) penetrating the outer circumferential surface and the inner circumferential surface, and impurities in the blood are passed through the membrane in the dialysate. It is comprised so that it can permeate | transmit.

  On the other hand, as shown in FIG. 2, the dialysis machine main body 6 bypasses the dual pump P formed across the dialysate introduction line L1 and the dialysate discharge line L2 and the dual pump P in the dialysate discharge line L2. It is mainly comprised from the connected bypass line L3 and the water removal pump 8 (peak provision means) connected to this bypass line L3. One end of the dialysate introduction line L1 is connected to the dialyzer 2 (dialyte introduction port 2c), and the other end is connected to a dialysate supply device 7 for preparing a dialysate having a predetermined concentration.

  One end of the dialysate discharge line L2 is connected to the dialyzer 2 (dialysate outlet port 2d), and the other end is connected to a waste fluid means (not shown). The dialysate supplied from the dialysate supply device 7 After reaching the dialyzer 2 through the dialysate introduction line L1, it is sent to the waste fluid means through the dialysate discharge line L2 and the bypass line L3. In addition, the code | symbol 9 and 10 in the figure has shown the warmer and deaeration means connected to the dialysate introduction line L1.

  The water removal pump 8 (water removal means) (peak giving means) is for removing water by removing water from the blood of the patient flowing in the dialyzer 2. That is, when the dewatering pump 8 is driven, the volume of the liquid discharged from the dialysate discharge line L2 becomes larger than the amount of dialysate introduced from the dialysate introduction line L1, and the larger volume is extracted from the blood. Moisture is removed. In addition, you may make it remove a water | moisture content from a patient's blood by means other than this water removal pump 8 (for example, what utilizes what is called a balancing chamber etc.).

  On the other hand, the arterial hematocrit sensor 5a according to the present embodiment is attached to the arterial blood circuit 1a and is based on a light reception voltage obtained by receiving light reflected from the blood flowing through the arterial blood circuit 1a. And a calibration curve obtained in advance from the relationship between the received light voltage and the blood concentration (hematocrit value). Such a calibration curve is obtained in advance using typical blood, and consists of a linear relationship (see symbol β in FIG. 5) between the light reception voltage obtained by measuring the representative blood and the hematocrit value. .

  Further, the venous hematocrit sensor 5b according to the present embodiment is attached to the venous blood circuit 1b and is based on a light reception voltage obtained by receiving light reflected from the blood flowing through the venous blood circuit 1b. And a calibration curve obtained in advance from the relationship between the received light voltage and the blood concentration (hematocrit value). Such a calibration curve is obtained in advance using typical blood, and consists of a linear relationship (see symbol α in FIG. 5) between the received light voltage obtained by measuring the representative blood and the hematocrit value. .

  As shown in FIGS. 3 and 4, the arterial hematocrit sensor 5 a and the venous hematocrit sensor 5 b mainly include a housing portion 14, a pair of light emitting elements 15 and light receiving elements 16, and a slit 17. . The casing 14 is formed of a resin molded product that constitutes the main body of the arterial hematocrit sensor 5a and the venous hematocrit sensor 5b, and has a groove 14a formed in the longitudinal direction on the surface thereof. The groove 14a can be fitted with a part of the flexible tube C constituting the arterial blood circuit 1a or the venous blood circuit 1b. In addition, the code | symbol 19 in the figure has shown the light emitting element (LED) for measuring oxygen saturation etc. FIG.

  The slit 17 is formed by cutting out the bottom surface of the groove 14a, and is formed over a predetermined dimension in the extending direction of the groove 14a. Further, a housing space S (see FIG. 4) for housing the light emitting element 15 and the light receiving element 16 is formed on the inner side of the housing portion 14 from the slit 17, and the housing space S and the groove 14a are formed. The slits 17 communicate with each other. In addition, a lid F that covers the surface (the surface on which the grooves 14 a and the slits 17 are formed) is attached to the casing 14, and can be used while covering the surface of the casing 14 with the lid F. The hematocrit value is measured in a state where the flexible tube C is fitted. A rod-like locked portion 14b is formed at a predetermined portion of the housing portion 14, and a claw-shaped locking portion Fa that can be locked with the locked portion 14b is formed on the lid portion F. The lid portion F that is formed and covers the housing portion 14 can be held.

  The light emitting element 15 is composed of, for example, an LED that can irradiate near infrared rays (near infrared LED), and the light receiving element 16 is composed of a photodiode. The light-emitting element 15 and the light-receiving element 16 are formed on a single substrate 18 with a predetermined distance from each other. The flexible tube C) can be faced.

  An amplification circuit for amplifying a signal from the light receiving element 16 is formed on the substrate 18. Thereby, when the light receiving element 16 receives light and outputs an electric signal corresponding to the illuminance, the light can be amplified by the amplifier circuit. The light emitted from the light emitting element 15 reaches the flexible tube C fitted into the groove 14a through the slit 17, and is reflected by the blood flowing through the flexible tube C to be received by the light receiving element 16. (A so-called reflective sensor configuration).

  Then, based on the received light voltage generated by the light receiving element 16, a hematocrit value indicating the blood concentration is obtained. That is, each component of blood such as red blood cells and plasma has its own light absorption characteristics, and this property is used to quantify the red blood cells necessary for measuring the hematocrit value electro-optically. Thus, the hematocrit value can be obtained. Specifically, near-infrared rays irradiated from the light emitting element 15 are influenced by absorption and scattering when reflected on blood, and are received by the light receiving element 16. The light absorption / scattering rate is analyzed from the intensity of the received light, and the hematocrit value (blood concentration) is calculated.

  In the present embodiment, the arterial hematocrit sensor 5a and the venous hematocrit sensor 5b are configured by the so-called reflective sensors as described above. The hematocrit value (blood concentration) may be measured based on the received light voltage obtained by receiving the transmitted light with the light receiving element 16. That is, the arterial hematocrit sensor 5a and the venous hematocrit sensor 5b are configured to receive a hematocrit value (based on a light reception voltage obtained by receiving light transmitted or reflected from the blood flowing through the arterial blood circuit 1a or the venous blood circuit 1b. Any device capable of measuring (blood concentration) (so-called optical sensor) is sufficient.

  Here, the arterial hematocrit sensor 5a and the venous hematocrit sensor 5b according to this embodiment are electrically connected to the control means 11 in the dialyzer body 6, respectively. The control means 11 is composed of, for example, a microcomputer, and a calibration means 12 for calibrating calibration curves of the arterial hematocrit sensor 5a (arterial blood concentration sensor) and the venous hematocrit sensor 5b (venous blood concentration sensor); Recirculated blood detection means 13 is formed for detecting the recirculated blood that is returned from the venous blood circuit 1b to the patient and then flows to the arterial blood circuit 1a.

  The calibration unit 12 sequentially performs the first step, the second step, the third step, and the fourth step, thereby configuring the calibration curve α of the venous hematocrit sensor 5b to obtain the calibration curve α ′ (see FIG. 8). At the same time, the calibration curve β of the arterial hematocrit sensor 5a is calibrated to obtain a calibration curve β ′ (see FIG. 8). In the first step, the blood pump 3 is driven in a state where water removal by the water removal pump 8 is not performed to circulate blood extracorporeally in the blood circuit 1, and light is received by the arterial hematocrit sensor 5a and the venous hematocrit sensor 5b, respectively. In this step, a voltage is detected, and a blood concentration is obtained based on each calibration curve corresponding to each detected light reception voltage.

In this first step, the water removal pump 8 (water removal means) is in a stopped state, and the water removal speed is 0. On the other hand, in the first step, the dual pump P may be operating, but it is preferably stopped to improve accuracy. For the sake of explanation, as shown in FIG. 5, the calibration curve before calibration in the arterial hematocrit sensor 5a is indicated by a straight line β (inclination a _a0 ), and the calibration curve before calibration in the venous hematocrit sensor 5b is denoted by α The straight line (tilt a _v0 ) is shown.

In the first step, as shown in FIG. 6, the received light voltage obtained by the arterial hematocrit sensor 5a is V _A0 , the hematocrit value converted by the calibration curve β is Ht _A0, and the venous hematocrit sensor 5b. The photoreception voltage obtained in step V is V _V0 , and the hematocrit value converted by the calibration curve α is Ht _V0 . In the first step, since the blood is not dehydrated, the hematocrit value Ht _A0 and the hematocrit value Ht _V0 should be the same, but may differ depending on the error. )

When the first step is completed, the second step is performed. In the second step, the blood pump 3 is driven in a state where water removal is performed by the water removal pump 8 (water removal means) to circulate blood extracorporeally in the blood circuit 1, and the received light voltage is received by the venous hematocrit sensor 5b. This is a step of detecting V _V1 and calculating a theoretical hematocrit value Ht _true by calculation using the hematocrit value V _V0 obtained by the detection of the venous hematocrit sensor 5b in the first step as a parameter. In the second step, the dual pump P may be operating, but is preferably stopped to improve accuracy.

That is, in the second step, since the patient's blood is circulated extracorporeally while being dehydrated by the dialyzer 2, the blood is concentrated in the process of passing through the dialyzer 2, so that it is located upstream from the dialyzer 2. The hematocrit value measured by the arterial hematocrit sensor 5a does not change. On the other hand, since blood concentrated by the water removal rate reaches the venous hematocrit sensor 5b located downstream of the dialyzer 2, the light reception voltage obtained by the venous hematocrit sensor 5b changes from V _V0 to V _V1 . Will change.

Therefore, the calculation in the second step is Ht _true = Qb / (Qb−Quf) × Ht _V0 (where Ht _true is the theoretical hematocrit value, Qb is the extracorporeal blood flow rate of the blood, Quf is the water removal rate, and Ht _V0. Is performed by an arithmetic expression (hematocrit value obtained in the first step). When the theoretical hematocrit value Ht _true thus obtained is plotted on the graph displaying the calibration curves α and β, it is as shown in FIG.

When the second step is completed, the third step is performed. In the third step, the received light voltage V _V0 and the hematocrit value Ht _{V0 of} the venous hematocrit sensor 5b obtained in the first step, the received light voltage V _{V1 of} the venous hematocrit sensor 5b obtained in the second step, and This is a step of obtaining the relationship between the received light voltage of the venous hematocrit sensor 5b and the blood concentration based on the theoretical hematocrit value Ht _true and calibrating the calibration curve of the venous hematocrit sensor 5b based on the relationship.

Specifically, the relationship between the received light voltage of the venous hematocrit sensor 5b and the hematocrit value obtained in the third step is the slope a _Vtrue = (Ht _true −Ht _{V0 as} shown by the straight line α ′ in FIG. ) / (V _V1 −V _V0 ). As a result, the calibration curve α of the venous hematocrit sensor 5b can be calibrated to the calibration curve α ′. Thus, it is possible to obtain the calibration curve α before calibration and the calibrated calibration curve α ′ in the venous hematocrit sensor 5b.

When the third step is finished, the fourth step is performed. In the fourth step, the calibration curve β of the arterial hematocrit sensor 5a is based on the relationship between the calibration curve α ′ of the venous hematocrit sensor 5b calibrated in the third step and the calibration curve of the venous hematocrit sensor 5b before calibration. Is a process of calibrating. Specifically, the calibration curve α ′ of the calibrated venous hematocrit sensor 5b has a slope a _Vtrue = (Ht _true −Ht _V0 ) / (V _V1 −V _V0 ) and the calibration curve of the venous hematocrit sensor 5b before calibration. The ratio of α to the slope a _v0 is obtained, and the calibration curve β of the arterial hematocrit sensor 5a is calibrated based on the ratio to obtain a calibration curve β ′ (see FIG. 8).

  That is, in the arterial hematocrit sensor 5a, it is considered that there is a difference in inclination similar to the difference between the inclination of the calibration curve α before calibration and the inclination of the calibration curve α ′ after calibration as in the vein side hematocrit sensor 5b. For example, the calibration of the actual solution can be performed by correcting the slope ratio of the calibration curve (α, α ′) before and after calibration of the vein-side hematocritical sensor 5b by multiplying the calibration curve β of the arterial-side hematocrit sensor 5a. It can be done.

The calibration of the calibration curves of the arterial hematocrit sensor 5a and the venous hematocrit sensor 5b is thus completed, and the hematocrit value being treated is detected using the calibration curves α ′ and β ′ after calibration. Then, using this detected hematocrit value, ΔBV (%) = (Ht ₀ / Ht _t −1) × 100 (where Ht ₀ is the initial hematocrit value and Ht _t is the hematocrit at the time of measurement) The rate of change in circulating blood volume (ΔBV) is determined by the value), and the rate of change in circulating blood volume (ΔBV) is used as a measure of the water removal rate.

  According to the present embodiment, the calibration curves α and β are calibrated based on the actual blood of the patient through the first to fourth steps, so that the calibration curves of at least the arterial hematocrit sensor 5a and the venous hematocrit sensor 5b are obtained. The inclination of (α, β) can be calibrated, and measurement errors can be suppressed. Further, as the arterial blood concentration sensor and the venous blood concentration sensor, the arterial hematocrit sensor 5a and the venous hematocrit sensor 5b capable of measuring the hematocrit value indicating the blood concentration are used. The rate of change in blood volume (ΔBV) can be determined easily and accurately.

Further, the second step is Ht _true = Qb / (Qb−Quf) × Ht _V0 (where Ht _true is the theoretical hematocrit value, Qb is the extracorporeal blood flow rate of the blood, Quf is the water removal rate, and Ht _V0 is the first rate. Since the calculation is performed using the calculation formula (hematocrit value obtained in one step), the calibration curve can be calibrated more accurately. Furthermore, the fourth step obtains a ratio between the slope of the calibration curve α ′ of the calibrated vein-side hematocrit sensor 5b and the slope of the calibration curve α of the vein-side hematocrit sensor 5b before the calibration, and based on the ratio. Since the calibration curve β of the arterial hematocrit sensor 5a is calibrated, the calibration curve β of the arterial hematocrit sensor 5a can be calibrated by a simpler calculation.

  On the other hand, in the present embodiment, there is provided a peak applying means capable of applying a peak peculiar to a change in blood concentration by concentrating or diluting blood rapidly and for a short time, and the arterial hematocrit sensor 5a and vein The side hematocrit sensor 5b is capable of detecting a specific peak imparted by the peak imparting means. The peak imparting means according to the present embodiment is constituted by a water removal pump 8. The water removal pump 8 performs water removal abruptly and in a short time in addition to water removal necessary for dialysis treatment. Can be concentrated. The peak applying means is not limited to the dewatering pump 8, and any other form may be used as long as it can give a peak specific to changes in blood concentration by performing rapid or short-time blood concentration or dilution. It may be a thing.

  For example, water removal at a constant rate performed during dialysis treatment is temporarily stopped (extracorporeal circulation is being performed), and when the measured hematocrit value is stabilized, the water removal pump 8 is driven rapidly and for a short time. By performing water removal, it is configured so that a peculiar peak can be given to a change in blood concentration (hematocrit value) during that time. Here, the term “abrupt and short time” in the present invention means a size and time enough to confirm the pulse applied after passing through the circuit, and “specific” means fluctuations in the pump and the body of the patient. It can be distinguished from fluctuation patterns due to other factors caused by movement.

  More specifically, as shown in FIG. 9, at a time t1, water removal at a constant rate (normal water removal) is stopped, and thereafter, when the measured hematocrit value reaches a stable time t2. The water pump 8 is driven at a higher speed than usual until time t3. The time t2 to t3 is a minute time. Thereby, compared with normal water removal, water removal can be performed rapidly and in a short time, and for example, a specific peak can be given in the hematocrit value as shown in FIG.

  However, since the arterial hematocrit sensor 5a is disposed in the arterial blood circuit 1a, it detects the hematocrit value of the blood collected from the patient via the arterial puncture needle a during dialysis treatment, and the venous hematocrit. Since the sensor 5b is disposed in the venous blood circuit 1b, it detects the hematocrit value of the blood purified by the dialyzer 2 and returned to the patient. That is, the given peculiar peak is first detected by the venous hematocrit sensor 5b (see FIG. 10), and then when the blood reaches the arterial blood circuit 1a again and is recirculated, The remaining characteristic peak can be detected (see FIG. 11) by the arterial hematocrit sensor 5a.

  In the present embodiment, the arterial hematocrit sensor 5a and the venous hematocrit sensor 5b are electrically connected to the recirculating blood detection means 13, and whether or not a specific peak is given by the venous hematocrit sensor 5b as described above. This can be confirmed, and the presence or absence of recirculated blood can be detected by the arterial hematocrit sensor 5a.

  Further, the recirculating blood detection means 13 compares the hematocrit values (specific peaks) detected by the arterial hematocrit sensor 5a and the venous hematocrit sensor 5b, and the recirculating blood in the blood flowing through the arterial blood circuit 1a is detected. It is assumed that the proportion of the share can be calculated. Specifically, when there is blood recirculation, the time from when a specific peak is given by the water removal pump 8 until the blood reaches the venous hematocrit sensor 5b (time t5 in FIG. 10) and recirculation Then, the time to reach the arterial hematocrit sensor 5a (t7 in FIG. 11) is predicted, and is detected by the venous hematocrit sensor 5b when the time t5 has elapsed after the application of a specific peak by the water removal pump 8. The recirculating blood detection means 13 compares the hematocrit value with the hematocrit value detected by the arterial hematocrit sensor 5a when the time t7 has elapsed.

  Thus, by predicting the time t5 until the blood reaches the venous hematocrit sensor 5b and the time t7 until the blood reaches the arterial hematocrit sensor 5a by recirculation, the cardiopulmonary recirculation (the purified blood becomes the heart Or a phenomenon of being pulled out of the body without passing through other tissues or organs) and recirculation to be measured. Instead of this method, the recirculating blood detection means 13 recognizes that the hematocrit value detected by the arterial hematocrit sensor 5a and the venous hematocrit sensor 5b exceeds a predetermined value, and the value exceeds the value. You may make it compare hematocrit values.

  Then, based on the time-hematocrit value graphs as shown in FIG. 10 and FIG. 11, changes in the hematocrit values of the arterial hematocrit sensor 5a and the venous hematocrit sensor 5b are obtained, and the time portion to be compared as described above ( The area of the change part is calculated by a mathematical method such as an integration method. For example, the area of the change portion (portion from t5 to t6 in FIG. 10) by the venous hematocrit sensor 5b is Sv, and the area of the change portion (portion from t7 to t8 in FIG. 11) by the arterial hematocrit sensor 5a is Sa. In other words, the ratio of recirculated blood (recirculation rate) Rrec is obtained by the following arithmetic expression.

  Rrec (%) = Sa / Sv × 100

  Here, the time of the change portion (time interval from t7 to t8) by the arterial hematocrit sensor 5a is diffused in the process in which blood with a specific peak flows from the venous hematocrit sensor 5b to the arterial hematocrit sensor 5a. In view of this, it is set to be larger than the time of the changing portion (time interval from t5 to t6) by the vein-side hematocrit sensor 5b. In the case where there is no blood recirculation, Sa is 0, so the ratio of recirculated blood is 0 (%). Thereby, in addition to the presence or absence of blood recirculation, the ratio can be recognized by the medical staff, and subsequent treatments (re-puncture the puncture needle or re-shunt formation to suppress blood recirculation) Etc.).

  According to this embodiment, a peak specific to changes in blood concentration can be imparted by abrupt and short-time blood concentration or dilution, and the arterial hematocrit sensor 5a and venous hematocrit sensor 5b Since the characteristic peak can be detected and the recirculated blood can be detected based on the characteristic peak detected by the arterial hematocrit sensor 5a and the venous hematocrit sensor 5b, the arterial hematocrit sensor 5a and the vein In addition to calibration of the calibration curve of the side hematocrit sensor 5b, recirculated blood can also be detected.

  Further, by using two of the arterial hematocrit sensor 5a and the venous hematocrit sensor 5b, the detected values of both can be compared without water removal, and these calibrations can be automatically performed. . Since the arterial hematocrit sensor 5a and the venous hematocrit sensor 5b are disposed on the inlet side and the outlet side of the dialyzer 2, respectively, the water removal performance of the dialyzer 2 can be monitored.

  By the way, in the said embodiment, although the peak provision means which can provide the peak peculiar to the change of the blood concentration by concentrating or diluting blood rapidly and for a short time is comprised by the water removal pump 8. FIG. Instead of this, another form of peak applying means may be used. Hereinafter, other embodiments will be described.

  As shown in FIG. 12, for example, as shown in FIG. 12, the dialysis apparatus body 6 applied as another embodiment of the present invention includes a dual pump P formed across the dialysate introduction line L1 and the dialysate discharge line L2, and a bypass line. L3 and a dewatering pump 8 connected to the bypass line L3, a pressurizing pump 20 that causes the dialysate to flow from the dialyzer 2 to the drainage side of the dual pump P, a bubble separation chamber 21, and air release The line L4 and the electromagnetic valve 22 are provided. In addition, the same code | symbol is attached | subjected to the component similar to previous embodiment, and those detailed description is abbreviate | omitted.

  The pressurizing pump 20 is connected between the dialyzer 2 and the duplex pump P in the dialysate discharge line L2, and is used to flow the dialysate from the dialyzer 2 to the duplex pump P. It consists of a positive displacement pump (pressure control type). The bubble separation chamber 21 is a so-called degassing chamber, and has a predetermined capacity connected between the pressurizing pump 20 and the duplex pump P in the dialysate discharge line L2, and traps bubbles in the dialysate. It is comprised so that it can do. From the bubble separation chamber 21, a bypass line L3 is extended and an air release line L4 is extended. The air release line L4 has a tip open to the atmosphere, and an electromagnetic valve 22 is connected to the air release line L4.

  The electromagnetic valve 22 can be opened and closed to open or close the atmosphere opening line L4. The bubble separation chamber 21 communicates with the outside air in the open state, and the bubble separation chamber 21 shuts off from the outside air in the closed state. It has become. Therefore, before or after dialysis treatment, if the electromagnetic valve 22 is operated to open the atmosphere release line L4, the bubbles trapped in the bubble separation chamber 21 can be released to the atmosphere.

  Here, the atmospheric release line L4 and the electromagnetic valve 22 in the present embodiment constitute a peak applying means of the present invention, and the dialyzer is operated by operating the electromagnetic valve 22 to open the atmospheric release line L4. The blood flowing through 2 can be concentrated rapidly and for a short time to give a unique peak. That is, during the dialysis treatment, when the solenoid valve 22 is operated to open the closed air release line L4, the outlet pressure of the pressurizing pump 20 becomes substantially equal to the atmospheric pressure. A high negative pressure is instantaneously generated, and rapid and short-time water removal (blood concentration) is performed on the blood flowing through the dialyzer 2 (blood flow path).

  As a result, it is much larger than the ultrafiltration pressure generated by driving the water removal pump 8, and a large amount of water can be removed from the blood in a short time, resulting in a change in blood concentration (hematocrit value). A unique peak can be given. The opening of the atmosphere opening line L4 by the electromagnetic valve 22 is a short time (in this embodiment, the opening of the atmosphere opening line L4 can be set to an arbitrary time of 10 seconds or less, and even one second is sufficient. It has a measurement accuracy), and the air release line L4 is closed by operating the solenoid valve 22 immediately. The opening time of the atmosphere opening line L4 by the electromagnetic valve 22 is controlled to be automatically optimized based on blood concentration information (information on the patient's blood concentration) and pressure information (venous pressure, dialysate pressure, etc.). Is preferred.

  Although the present embodiment has been described above, the present invention is not limited to this embodiment. For example, the recirculated blood detection means 13 may not be provided, and the recirculated blood may not be detected. Further, instead of the arterial hematocrit sensor 5a and the venous hematocrit sensor 5b, blood based on the received light voltage obtained by receiving the light transmitted or reflected to the blood flowing through the arterial blood circuit 1a and the venous blood circuit 1b. While the concentration can be measured, another form of sensor having a calibration curve obtained in advance from the relationship between the received light voltage and the blood concentration may be used. In the present embodiment, the dialysis device body 6 is composed of a dialysis monitoring device that does not incorporate a dialysate supply mechanism, but may be applied to a personal dialysis device that incorporates a dialysate supply mechanism. .

  Blood is extracorporeally circulated in the blood circuit without water removal by the water removal means, and the received light voltage is detected by the arterial blood concentration sensor and the venous blood concentration sensor, respectively. The first step of obtaining the blood concentration based on each corresponding calibration curve, and circulating the blood extracorporeally in the blood circuit in the state of water removal by the water removal means, and detecting the received light voltage by the venous blood concentration sensor And a second step of calculating a theoretical blood concentration by calculation using the blood concentration obtained by detection of the venous concentration sensor in the first step as a parameter, and a venous blood obtained in the first step. Based on the light reception voltage and blood concentration of the concentration sensor and the light reception voltage and theoretical blood concentration of the venous blood concentration sensor obtained in the second step, the venous blood concentration sensor A third step of obtaining the relationship between the photovoltage and the blood concentration and calibrating the calibration curve of the venous blood concentration sensor based on the relationship, and the calibration curve and calibration of the venous blood concentration sensor calibrated in the third step A blood purification device in which the fourth step of calibrating the calibration curve of the arterial blood concentration sensor based on the relationship with the calibration curve of the previous vein blood concentration sensor is performed, and the blood concentration sensor calibration method in the blood purification device Any other form may be used.

DESCRIPTION OF SYMBOLS 1 ... Blood circuit 1a ... Arterial side blood circuit 1b ... Vein side blood circuit 2 ... Dializer (blood purifier)
3 ... blood pump 4 ... air trap chamber 5a ... arterial hematocrit sensor (arterial blood concentration sensor)
5b ... Venous hematocrit sensor (venous blood concentration sensor)
6 ... dialyzer body 7 ... dialysate supply device 8 ... water removal pump (water removal means) (peak giving means)
DESCRIPTION OF SYMBOLS 9 ... Heater 10 ... Deaeration means 11 ... Control means 12 ... Calibration means 13 ... Recirculation blood detection means 14 ... Housing part 15 ... Light emitting element 16 ... Light receiving element 17 ... Slit 18 ... Substrate 19 ... Light emitting element 20 ... Pressure pump 22 ... Solenoid valve (peaking means)
L4 ... Open air line (peaking means)

Claims (10)

A blood circuit comprising an arterial blood circuit and a venous blood circuit for extracorporeal circulation of the patient's blood;
A blood purifier connected to the arterial blood circuit and the venous blood circuit, respectively, for purifying blood circulating outside the body;
Water removal means capable of removing water by removing water in the blood flowing through the blood purifier;
The blood concentration can be measured based on a light reception voltage obtained by receiving light transmitted or reflected to blood flowing through the artery side blood circuit and attached to the artery side blood circuit. An arterial blood concentration sensor having a calibration curve obtained in advance from the relationship;
A blood concentration can be measured based on a received light voltage obtained by receiving light transmitted or reflected to blood flowing through the venous blood circuit and attached to the venous blood circuit. A vein-side blood concentration sensor having a calibration curve obtained in advance from the relationship;
A blood purification apparatus comprising:
While comprising calibration means for calibrating calibration curves of the arterial blood concentration sensor and the venous blood concentration sensor,
Blood is extracorporeally circulated in the blood circuit without water removal by the water removal means, and the received light voltage is detected by the arterial blood concentration sensor and the venous blood concentration sensor, respectively. A first step of obtaining a blood concentration based on each calibration curve corresponding to the received light voltage;
Blood is extracorporeally circulated in the blood circuit in a state where water removal by the water removal means is performed, a light reception voltage is detected by the vein side blood concentration sensor, and the vein side concentration sensor of the first step A second step of calculating a theoretical blood concentration by calculation using the blood concentration obtained by detection as a parameter;
Based on the light reception voltage and blood concentration of the venous blood concentration sensor obtained in the first step, and the light reception voltage and theoretical blood concentration of the venous blood concentration sensor obtained in the second step. A third step of obtaining a relationship between the light reception voltage of the venous blood concentration sensor and the blood concentration, and calibrating a calibration curve of the venous blood concentration sensor based on the relationship;
A fourth step of calibrating the calibration curve of the arterial blood concentration sensor based on the relationship between the calibration curve of the venous blood concentration sensor calibrated in the third step and the calibration curve of the venous blood concentration sensor before calibration; ,
Is performed.   2. The blood purification apparatus according to claim 1, wherein the arterial blood concentration sensor and the venous blood concentration sensor comprise an arterial hematocrit sensor and a venous hematocrit sensor capable of measuring a hematocrit value indicating a blood concentration. In the second step, Ht _true = Qb / (Qb−Quf) × Ht _V0 (where Ht _true is the theoretical hematocrit value, Qb is the blood extracorporeal flow rate, Quf is the water removal rate, and Ht _V0 is the first rate. The blood purification apparatus according to claim 2, wherein the calculation is performed by an arithmetic expression (hematocrit value obtained in the process).   The fourth step obtains a ratio between the slope of the calibration curve of the venous blood concentration sensor calibrated and the slope of the calibration curve of the venous blood concentration sensor before calibration, and based on the ratio, the arterial blood The blood purification apparatus according to any one of claims 1 to 3, wherein a calibration curve of the concentration sensor is calibrated.   A peak applying means capable of giving a peak peculiar to a change in blood concentration by concentrating or diluting blood rapidly and for a short time, and the arterial blood concentration sensor and the venous blood concentration sensor A specific peak applied by the peak applying means can be detected, and is returned to the patient from the venous blood circuit based on the specific peak detected by the arterial blood concentration sensor and the venous blood concentration sensor. The blood purification apparatus according to any one of claims 1 to 4, wherein the recirculated blood that has been introduced into the arterial blood circuit again can be detected. A blood circuit comprising an arterial blood circuit and a venous blood circuit for extracorporeal circulation of the patient's blood;
A blood purifier connected to the arterial blood circuit and the venous blood circuit, respectively, for purifying blood circulating outside the body;
Water removal means capable of removing water by removing water in the blood flowing through the blood purifier;
The blood concentration can be measured based on a light reception voltage obtained by receiving light transmitted or reflected to blood flowing through the artery side blood circuit and attached to the artery side blood circuit. An arterial blood concentration sensor having a calibration curve obtained in advance from the relationship;
A blood concentration can be measured based on a received light voltage obtained by receiving light transmitted or reflected to blood flowing through the venous blood circuit and attached to the venous blood circuit. A vein-side blood concentration sensor having a calibration curve obtained in advance from the relationship;
A blood concentration sensor calibration method in a blood purification apparatus comprising:
Blood is extracorporeally circulated in the blood circuit without water removal by the water removal means, and the received light voltage is detected by the arterial blood concentration sensor and the venous blood concentration sensor, respectively. A first step of obtaining a blood concentration based on each calibration curve corresponding to the received light voltage;
Blood is extracorporeally circulated in the blood circuit in a state where water removal by the water removal means is performed, a light reception voltage is detected by the vein side blood concentration sensor, and the vein side concentration sensor of the first step A second step of calculating a theoretical blood concentration by calculation using the blood concentration obtained by detection as a parameter;
Based on the light reception voltage and blood concentration of the venous blood concentration sensor obtained in the first step, and the light reception voltage and theoretical blood concentration of the venous blood concentration sensor obtained in the second step. A third step of obtaining a relationship between the light reception voltage of the venous blood concentration sensor and the blood concentration, and calibrating a calibration curve of the venous blood concentration sensor based on the relationship;
A fourth step of calibrating the calibration curve of the arterial blood concentration sensor based on the relationship between the calibration curve of the venous blood concentration sensor calibrated in the third step and the calibration curve of the venous blood concentration sensor before calibration; ,
A method for calibrating a blood concentration sensor in a blood purification apparatus, wherein:   7. The blood in the blood purification apparatus according to claim 6, wherein the arterial blood concentration sensor and the venous blood concentration sensor comprise an arterial hematocrit sensor and a venous hematocrit sensor capable of measuring a hematocrit value indicating the blood concentration. Density sensor calibration method. In the second step, Ht _true = Qb / (Qb−Quf) × Ht _V0 (where Ht _true is the theoretical hematocrit value, Qb is the blood extracorporeal flow rate, Quf is the water removal rate, and Ht _V0 is the first rate. 8. The method for calibrating a blood concentration sensor in a blood purification apparatus according to claim 7, wherein the calculation is performed by an arithmetic expression (hematocrit value obtained in the process).   The fourth step obtains a ratio between the slope of the calibration curve of the venous blood concentration sensor calibrated and the slope of the calibration curve of the venous blood concentration sensor before calibration, and based on the ratio, the arterial blood The calibration method of the blood concentration sensor in the blood purification apparatus according to any one of claims 6 to 8, wherein a calibration curve of the concentration sensor is calibrated.   A sharp and short-time concentration or dilution of blood can give a unique peak to changes in blood concentration, and the arterial blood concentration sensor and the venous blood concentration sensor detect the unique peak. Based on the peculiar peaks detected by the arterial blood concentration sensor and the venous blood concentration sensor, blood returned to the patient from the venous blood circuit is led to the arterial blood circuit again. The method for calibrating a blood concentration sensor in a blood purification apparatus according to any one of claims 6 to 9, wherein recirculating blood flowing is detectable.

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