Blood purification device

Abstract

A blood purification device, which allows an operator such as a medical professional to freely change the start time or end time of a local characteristic change and which can simulate calculation of a recirculated blood ratio, is provided with: a characteristic change-imparting section that can impart a local concentration change in which a specific peak is formed in a concentration change of blood that extracorporeally circulates in a blood circuit (1); a first detection section (5a) and a second detection section (5b) that detect a local concentration change imparted by the characteristic change-imparting section; and a recirculation detection section (17), which detects recirculated blood on the basis of a local concentration change β detected by the first detection section (5a) and a local concentration change α detected by the second detection section (5b), and which calculates a recirculated blood ratio. The blood purification device has a change operation section (19) for freely effecting a change operation on the prescribed start time (R1, W1) and end time (R2, W2).

Description

Blood purification device

[0001] The present invention relates to a blood purification device that detects recirculated blood, which is blood returned to a patient from a venous blood circuit and then guided back into an arterial blood circuit.

[0002] In general, in blood purification therapy, such as hemodialysis, a patient's blood is circulated extracorporeally through a blood circuit, and blood purification is performed using a dialyzer. However, when, for example, an arterial puncture needle and a venous puncture needle are inserted into a patient's shunt (a site where an artery and a vein are connected by a surgical procedure) to perform extracorporeal circulation, the purified blood returned to the patient through the venous puncture needle may be recirculated back into the blood circuit through the arterial puncture needle without passing through the patient's organs, resulting in recirculation of blood. When this recirculation occurs, the purified blood must be further circulated extracorporeally, which reduces the amount of blood circulating extracorporeally that needs to be purified, resulting in a problem of reduced blood purification efficiency.

[0003] To detect such recirculated blood, a dialysis machine has been proposed that can detect blood recirculation by driving a water removal pump to give a specific peak to the change in concentration of blood circulating extracorporeally, and using this as a marker, as disclosed in Patent Document 1. According to the dialysis machine disclosed in this document, a sensor that detects blood concentration (a sensor that detects hemoglobin concentration) is disposed in the arterial blood circuit, and blood recirculation during dialysis treatment can be detected by detecting the specific peak with this sensor.

[0004] Special Publication No. 2000-502940

[0005] However, conventional blood purification devices face the following challenges when calculating the recirculation rate or the patient's shunt flow rate. When a local concentration change is applied, the detected local concentration change may vary depending on the patient's condition, treatment environment, and other factors. Therefore, to accurately calculate the recirculation rate, it is necessary to accurately determine the start and end points of the local concentration change. On the other hand, when the recirculation rate is calculated based on the local concentration change detected by the detection unit, the start and end points of the local concentration change used as the basis for the calculation may be unclear, leading to demands from medical professionals to change them at will. Similar challenges also exist when calculating the recirculation rate based on changes in other blood characteristics, such as blood temperature, instead of blood concentration. Here, "blood characteristics" refers not only to blood concentration but also to general blood characteristics, such as blood temperature.

[0006] The present invention has been made in consideration of the above circumstances, and aims to provide a blood purification device that allows an operator, such as a medical professional, to arbitrarily change the start or end point of local characteristic changes and to simulate the calculation of the proportion of recirculated blood.

[0007] One embodiment of the present invention is a blood purification device that circulates a patient's blood extracorporeally through a blood circuit having an arterial blood circuit and a venous blood circuit, and purifies the blood. The blood purification device comprises: a characteristic change imparting unit that can impart a local characteristic change having a peak specific to the characteristic change of the blood circulating extracorporeally through the blood circuit; first and second detection units that are attached to the arterial blood circuit and the venous blood circuit, respectively, and detect the local characteristic change imparted by the characteristic change imparting unit; and a recirculation detection unit that detects recirculated blood, which is blood returned to the patient from the venous blood circuit and is guided back into the arterial blood circuit based on the local characteristic change detected by the first detection unit and the local characteristic change detected by the second detection unit, and calculates the ratio of the recirculated blood. The blood purification device also has a change operation unit that identifies the start and end points of the local characteristic change detected by the recirculation detection unit and arbitrarily changes the identified start and end points.

[0008] According to the present invention, the recirculation detection unit identifies the start or end point of the local characteristic change detected by the first detection unit and the second detection unit, and has a modification operation unit that allows the identified start and end points to be changed at will.This allows an operator, such as a medical professional, to identify the start or end point of the local characteristic change at will, and allows the calculation of the proportion of recirculated blood to be simulated.

[0009] Schematic diagram showing a blood purification device according to an embodiment of the present invention. Block diagram showing the main components of the blood purification device. Block diagram showing the recirculation detection unit of the blood purification device. Graph showing local concentration changes detected by the second detection unit and the first detection unit of the blood purification device. Flowchart showing the control content by the control unit of the blood purification device. Flowchart showing the control content by the control unit of the blood purification device, related to the operation of the change operation unit. Schematic diagram showing the display by the display unit of the blood purification device.

[0010] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The blood purification device according to this embodiment purifies a patient's blood while circulating it extracorporeally, and is applied to a hemodialysis device used in hemodialysis treatment. As shown in Fig. 1, this hemodialysis device is capable of mounting a blood circuit 1 connected to a dialyzer 2 as a blood purification unit, and includes a dialysis device main body 6 that supplies dialysate to the dialyzer 2 while removing water from the dialyzer 2, and a control unit 16, a recirculation detection unit 17, a display unit 18, and a change operation unit 19 arranged in the dialysis device main body 6.

[0011] As shown in the figure, the blood circuit 1 is mainly composed of an arterial blood circuit 1a and a venous blood circuit 1b, each made of flexible tubes, with a dialyzer 2 connected between the arterial blood circuit 1a and the venous blood circuit 1b. An arterial puncture needle a is connected to the tip of the arterial blood circuit 1a, and a peristaltic blood pump 3, a debubbling air trap chamber 4a, and a first detector 5a are disposed along the arterial blood circuit 1a. On the other hand, a venous puncture needle b is connected to the tip of the venous blood circuit 1b, and a second detector 5b and a debubbling air trap chamber 4b are disposed along the arterial blood circuit 1a.

[0012] When the blood pump 3 is driven with the arterial puncture needle a and the venous puncture needle b inserted into the patient, the patient's blood passes through the arterial blood circuit 1a, is debubbled in the air trap chamber 4a, and reaches the dialyzer 2. After being purified by the dialyzer 2, the patient's blood passes through the venous blood circuit 1b, is debubbled in the air trap chamber 4b, and returns to the patient's body. In this way, the patient's blood can be purified by the dialyzer 2 while being circulated extracorporeally through the blood circuit 1.

[0013] The dialyzer 2 has a housing formed with a blood inlet port 2a, a blood outlet port 2b, a dialysate inlet port 2c, and a dialysate outlet port 2d, of which the base end of the arterial blood circuit 1a is connected to the blood inlet port 2a, and the base end of the venous blood circuit 1b is connected to the blood outlet port 2b. The dialysate inlet port 2c and the dialysate outlet port 2d are connected to a dialysate inlet line 7 and a dialysate outlet line 8, respectively, which are extended from the dialysis device main body 6.

[0014] The dialyzer 2 contains a plurality of hollow fibers, the interior of which serves as a blood flow path, and the space between the outer circumferential surface of the hollow fibers and the inner circumferential surface of the housing serves as a dialysate flow path. The hollow fibers have many minute pores that penetrate from the outer circumferential surface to the inner circumferential surface, forming hollow fiber membranes, which allow impurities in the blood to pass through into the dialysate.

[0015] On the other hand, the dialysis device main body 6 is configured to include a duplex pump C, a bypass line 9 connected to the dialysate discharge line 8 so as to bypass the drain side Cb of the duplex pump C, a water removal pump 10 connected to the bypass line 9, a pressure pump 11 for causing the dialysate to flow from the dialyzer 2 to the drain side Cb of the duplex pump C, a bubble separating chamber 12, an atmospheric release line 13, and a solenoid valve 14.

[0016] The duplex pump C is disposed across the dialysate inlet line 7 and the dialysate outlet line 8, and serves to introduce dialysate from the dialysate inlet line 7 to the dialyzer 2 and to discharge the dialysate introduced into the dialyzer 2 from the dialysate outlet line 8. That is, the duplex pump C is a metering pump with a supply side Ca and a drain side Cb of approximately equal volume, and the dialysate flow path from the supply side Pa to the drain side Pb (specifically, the flow path downstream of the duplex pump C in the dialysate inlet line 7, the flow path upstream of the duplex pump C in the dialysate outlet line 8, and the dialysate flow path of the dialyzer 2) forms a closed flow path (a flow path that is kept sealed) when the solenoid valve 14 is closed.

[0017] The pressure pump 11 is connected between the dialyzer 2 and the duplex pump C in the dialysate discharge line 8, and serves to flow the dialysate from the dialyzer 2 to the duplex pump C. The pressure pump 11 is a non-positive displacement pump (pressure controlled type) such as a centrifugal type. The water removal pump 10, which will be described later, is also a non-positive displacement pump (pressure controlled type) such as a centrifugal type, similar to the pressure pump 11.

[0018] One end of the dialysate inlet line 7 is connected to the dialysate inlet port 2c of the dialyzer 2, and the other end is connected to a dialysate supply device (not shown) that prepares dialysate of a predetermined concentration. One end of the dialysate outlet line 8 is connected to the dialysate outlet port 2d of the dialyzer 2, and the other end is connected to drainage means (not shown). The dialysate supplied from the dialysate supply device passes through the dialysate inlet line 7 to the dialyzer 2, and then passes through the dialysate outlet line 8 and a bypass line 9 to be sent to the drainage means.

[0019] The ultrafiltration pump 10 is used to remove water from the patient's blood flowing through the dialyzer 2. That is, when the ultrafiltration pump 10 is driven, the volume of the liquid discharged from the dialysate discharge line 8 becomes greater than the volume of dialysate introduced from the dialysate inlet line 7, because the duplex pump C is a fixed-volume type, and water is removed from the blood by the amount of the greater volume.

[0020] The bubble separating chamber 12 is a so-called degassing chamber, and has a predetermined capacity and is connected between the pressure pump 11 and the duplex pump C in the dialysate discharge line 8, so as to be able to capture bubbles in the dialysate. The bypass line 9 described above is extended from the bubble separating chamber 12, as well as an atmosphere release line 13. The tip of the atmosphere release line 13 is open to the atmosphere, and a solenoid valve 14 serving as valve means is connected midway along the line.

[0021] The solenoid valve 14 can be opened and closed to open or close the atmosphere release line 13. In the open state, the bubble separation chamber 12 communicates with the outside air, and in the closed state, the bubble separation chamber 12 is cut off from the outside air. Then, before or after dialysis treatment, the solenoid valve 14 is operated to open the atmosphere release line 13, thereby releasing the air bubbles trapped in the bubble separation chamber 12 into the atmosphere.

[0022] In addition, a supply line La is connected to the dialysate introduction line 7 according to this embodiment. The supply line La is capable of supplying dialysate as a replacement fluid to the blood circuit 1, and its base end is connected to a portion of the dialysate introduction line 7 between the supply side Ca of the duplex pump C and the dialysate introduction port 2c of the dialyzer 2, and its tip branches into a pre-replacement fluid supply line La1 and a post-replacement fluid supply line La2, which are connected to the air trap chamber 4a of the arterial blood circuit 1a and the air trap chamber 4b of the venous blood circuit 1b, respectively.

[0023] A fluid replacement pump 15, which is a peristaltic pump similar to the blood pump 3, is disposed in the supply line La. During the blood purification treatment, by driving the fluid replacement pump 15, the dialysate in the dialysate introduction line 7 is supplied to the arterial blood circuit 1a via the pre-fluid replacement supply line La1, enabling pre-fluid replacement, and is also supplied to the venous blood circuit 1b via the post-fluid replacement supply line La2, enabling post-fluid replacement.

[0024] Here, the atmosphere vent line 13 and the solenoid valve 14 in this embodiment constitute the characteristic change imparting unit of the present invention, and by operating the solenoid valve 14 to open the atmosphere vent line 13, it is possible to impart a local concentration change (characteristic change) with a specific peak by performing a rapid and short-term concentration on the blood flowing through the dialyzer 2. That is, during dialysis treatment, when the solenoid valve 14 is operated to open the atmosphere vent line 13 that is in a closed state, the outlet pressure of the pressure pump 11 becomes approximately equal to atmospheric pressure, and therefore a momentary high negative pressure is generated upstream of the pressure pump 11, and rapid and short-term water removal (hemoconcentration) is performed on the blood flowing through the dialyzer 2 (blood flow path).

[0025] This allows a large amount of water to be removed from the blood in a short time at a pressure far greater than the ultrafiltration pressure generated by driving the water removal pump 10, and a unique peak can be imparted to the change in blood concentration (hematocrit value). The solenoid valve 14 opens the atmosphere vent line 13 in a short time (in this embodiment, the opening of the atmosphere vent line 13 can be set to any time equal to or less than 10 seconds, and even 1 second provides sufficient measurement accuracy), and the solenoid valve 14 is immediately operated to close the atmosphere vent line 13.

[0026] The time for which the solenoid valve 14 opens the air vent line 13 is preferably automatically controlled to be optimal based on blood concentration information (information about the patient's blood concentration) and pressure information (venous pressure, dialysate pressure, etc.). The term "sudden and short-term" in the present invention refers to a magnitude and duration that allows the applied pulse to be confirmed after passing through the circuit, and "unique" refers to a variation pattern that can be distinguished from variations due to other factors such as pump fluctuations or patient movement.

[0027] The first and second detectors 5a, 5b are disposed in the arterial and venous blood circuits 1a, 1b, respectively, to detect the concentration (specifically, the hematocrit value) of the blood flowing through these channels. The first and second detectors 5a, 5b are composed of hematocrit sensors equipped with a light-emitting element such as an LED and a light-receiving element such as a photodiode, and are configured to detect the hematocrit value, which indicates the concentration of the patient's blood, by irradiating the blood with light from the light-emitting element and receiving the transmitted or reflected light with the light-receiving element.

[0028] Specifically, the first detector 5a and the second detector 5b determine the hematocrit value, which indicates the blood concentration, based on the electrical signal output from the light-receiving element. Each component of blood, such as red blood cells and plasma, has its own unique light absorption characteristic. By utilizing this characteristic, the red blood cells required for measuring the hematocrit value can be electro-optically quantified to determine the hematocrit value. The near-infrared light irradiated from the light-emitting element is absorbed and scattered upon entering the blood, and is then received by the light-receiving element. The hematocrit value can be calculated by analyzing the light absorption and scattering rate based on the intensity of the received light.

[0029] The first detector 5a configured as described above is disposed in the arterial blood circuit 1a and therefore detects the hematocrit value of blood collected from the patient via the arterial puncture needle a during dialysis treatment, while the second detector 5b is disposed in the venous blood circuit 1b and therefore detects the hematocrit value of blood purified by the dialyzer 2 and returned to the patient. When a local concentration change is imparted by opening the solenoid valve 14, the second detector 5b detects a local concentration change α forming a characteristic peak P1, as shown in Figure 4, and when the blood returns to the arterial blood circuit 1a and is recirculated, the first detector 5a detects a local concentration change β remaining in the recirculated blood and forming a characteristic peak P2.

[0030] The control unit 16 is composed of, for example, a microcomputer, and as shown in FIG. 2, is electrically connected to pumps such as a duplex pump C that introduces and discharges dialysate to the dialyzer 2 (blood purification unit), a blood pump 3 arranged in the blood circuit 1, a water removal pump 10 that removes water from the blood circulating extracorporeally through the blood circuit 1, a pressure pump 11, a replacement fluid pump 15 that introduces replacement fluid (dialysis fluid) into the blood circuit, and a drug injection pump (not shown) that injects a drug solution such as heparin into the blood circuit 1, as well as electromagnetic valves such as an electromagnetic valve 14 that can impart local concentration changes with peaks specific to changes in blood concentration, and is capable of controlling these pumps and electromagnetic valves.

[0031] 2, the control unit 16 according to this embodiment is connected to an instruction input unit SW2, and an operator can input instructions by operating the instruction input unit SW2. The instruction input unit SW2 may be any unit that can be operated by the operator at any timing to input instructions, and may be, for example, a switch unit displayed on a touch panel (including the display unit 18) or a mechanical switch.

[0032] Furthermore, the first and second detectors 5a, 5b according to this embodiment are electrically connected to a recirculation detector 17 disposed in the dialysis machine main body 6, and the recirculation detector 17 is electrically connected to a display 18 configured as a touch panel. The display 18 displays the local concentration changes α, β detected by the first and second detectors 5a, 5b in a graph, and in addition to the graph display, can also display the ratio of recirculated blood calculated by the recirculation detector 17 in numerical form.

[0033] 2, the display unit 18 according to this embodiment is connected to a switching input unit SW1, and can perform switching input by the operator operating the switching input unit SW1. Such instruction input unit SW2 can be any unit that can be operated by the operator at any timing to input, and may be, for example, a switch unit displayed on a touch panel (including the display unit 18) or a mechanical switch.

[0034] The recirculation detection unit 17 is configured with, for example, a microcomputer, and is capable of detecting recirculated blood, which is blood returned to the patient from the venous blood circuit 1b and then guided back into the arterial blood circuit 1a, based on the local concentration change β detected by the first detection unit 5a and the local concentration change α detected by the second detection unit 5b, and calculating the proportion of recirculated blood (recirculation rate). As shown in Figure 3, the recirculation detection unit 17 according to this embodiment is configured with a monitoring unit 17a, a graph creation unit 17b, a calculation unit 17c, and a memory unit 17d.

[0035] The monitoring unit 17a monitors the changes in blood concentration detected by the first detection unit 5a and the second detection unit 5b over time during blood purification treatment. The graph creation unit 17b creates a graph showing local concentration changes α and β based on the changes in blood concentration monitored over time by the monitoring unit 17a, and the calculation unit 17c calculates the proportion of recirculated blood (recirculation rate) based on the graph created by the graph creation unit 17b. The changes in blood concentration monitored by the monitoring unit 17a, the graph created by the graph creation unit 17b, and the proportion of recirculated blood (recirculation rate) calculated by the calculation unit 17c are stored in the memory unit 17d.

[0036] Specifically, recirculation detection unit 17 determines the change in hematocrit value (concentration change) from first detection unit 5a and second detection unit 5b based on a graph with elapsed time (integrated flow rate or time) on the horizontal axis and blood concentration (hematocrit value) on the vertical axis as shown in Figure 4, and calculates the area S1 of local concentration change α where characteristic peak P1 is formed and the area S2 of local concentration change β where characteristic peak P2 is formed using a mathematical method such as integration. Then, the proportion of recirculated blood (recirculation rate) Rrec is calculated using the following calculation formula.

[0037] Rrec (%)=S2 / S1×100

[0038] The proportion of recirculated blood (recirculation rate) Rrec thus determined is displayed on the display unit 18 so that it can be visually confirmed by a medical professional such as a doctor. If there is no blood recirculation, the above S2 will be 0, and the value displayed as the proportion of recirculated blood will be 0 (%). Furthermore, the display unit 18 according to this embodiment is capable of graphically displaying the local concentration changes detected by the first detection unit 5a and the second detection unit 5b, in addition to the recirculation rate, as shown in FIG. 4 , and is capable of displaying the local concentration change α at which the characteristic peak P1 is formed and the local concentration change β at which the characteristic peak P2 is formed, as curved graphs.

[0039] On the other hand, based on the blood concentrations detected by the first and second detectors 5 a and 5 b, the recirculation detector 17 creates a graph showing local concentration changes α and β, with the horizontal axis representing elapsed time (integrated flow rate or time) and the vertical axis representing blood concentration (hematocrit value), as shown in Fig. 4, and monitors the changes in blood concentration at a predetermined interval (e.g., every 0.1 seconds). This allows the detector 17 to detect the start time R1 and end time R2 of the local concentration change α at which the characteristic peak P1 is formed, and the start time W1 and end time W2 of the local concentration change β at which the characteristic peak P2 is formed, and to accurately calculate the area S1 of the local concentration change α and the area S2 of the local concentration change β.

[0040] As shown in FIG. 7, the blood purification device according to this embodiment is configured to graphically display the local concentration changes (α, β) detected by the first detection unit 5a and the second detection unit 5b on the display unit 18, and to calculate the areas S1 and S2 by identifying the start points (R1, W1) and end points (R2, W2) of the local concentration changes (α, β) detected by the first detection unit 5a and the second detection unit 5b using the recirculation detection unit 17.

[0041] Furthermore, specific display sections (D1 to D4) that identify the start time points (R1, W1) and end time points (R2, W2) of the local concentration change (α, β) displayed as a graph on the display section 18 are displayed. As shown in Fig. 7, the specific display sections (D1 to D4) are, for example, made up of thick lines, and an operator such as a medical professional can touch any of the specific display sections (D1 to D4) with a finger and move it as desired (specifically, slide it in either the left or right direction while maintaining the finger touch), thereby shifting the display position of the specific display section (D1 to D4) to the left or right.

[0042] The specific display sections (D1 to D4) are not limited to bold line displays, and may be specific designs, patterns, letters, etc., as long as they are displays that allow the start time (R1, W1) and end time (R2, W2) to be identified. In this embodiment, the display section 18 is configured as a touch panel, and the specific display sections (D1 to D4) are displayed on the screen of the display section 18, and the specific display sections (D1 to D4) are operated by touching and sliding with a finger. However, the specific display sections (D1 to D4) may also be moved to any position by operating a separate operating means (such as an operating key that can be physically operated to move the display position left or right) provided in the blood purification device.

[0043] The change operation unit 19 is composed of, for example, a microcomputer, and arbitrarily changes the start time (R1, W1) and end time (R2, W2) specified by the recirculation detection unit 17. The operator can arbitrarily slide the specific display units (D1 to D4) to change the start time (R1, W1) and end time (R2, W2). The recirculation detection unit 17 is configured to recalculate the proportion of recirculated blood based on the local concentration changes (α, β) from the start time (R1, W1) to the end time (R2, W2) arbitrarily changed by the change operation unit 19.

[0044] However, in this embodiment, the process of detecting recirculated blood using the recirculation detection unit 17 and calculating the proportion of recirculated blood is performed in a measurement process separate from the treatment process in which blood purification treatment is performed. During this measurement process, the control unit 16 changes the parameters for driving the pumps to be controlled (duplex pump C, blood pump 3, water removal pump 10, pressurization pump 11, fluid replacement pump 15, chemical solution infusion pump, etc.) to measurement parameters different from those used in the treatment process in which blood purification treatment is performed. This measurement process will be described based on the flowchart in Figure 5.

[0045] First, the measurement process is initiated upon input operation of the switch input unit SW1 by the operator. In S1, the control unit 16 temporarily changes the pump to be controlled to a measurement parameter, drives the pump based on the measurement parameter, and then in S2, waits until the blood concentration detected by the first detector 5a and the second detector 5b stabilizes. The measurement parameter is a parameter that slows or stops the pump (the pump to be controlled) from the speed during the treatment process. Then, upon input operation of the command input unit SW2 by the operator, the process proceeds to S3, where the solenoid valve 14 is operated to open the air vent line 13, thereby generating a localized concentration change with characteristic peaks P1 and P2.

[0046] The process then proceeds to S4, where the recirculation detection unit 17 detects recirculated blood based on the local concentration change α detected by the first detection unit 5a and the local concentration change β detected by the second detection unit 5b, and calculates the proportion of recirculated blood (recirculation rate). The calculated proportion of recirculated blood (recirculation rate) is displayed on the display unit 18 to prompt a medical professional, such as a doctor, to take action. After the recirculated blood is detected and the proportion of recirculated blood (recirculation rate) is calculated, the process proceeds to S5, where the control unit 16 returns from the measurement parameters to the treatment parameters, provided that the operator operates the switch input unit SW1. This completes the measurement process, and blood purification therapy can be performed based on the treatment parameters.

[0047] Thus, in the measurement process, the recirculation detection unit 17 detects recirculated blood and calculates the ratio of recirculated blood (recirculation rate), and the local concentration changes (α, β) detected by the first detection unit 5a and the second detection unit 5b are displayed as a graph on the display unit 18. In this graph, specific display units (D1 to D4) are displayed at the display positions of the start time (R1, W1) and end time (R2, W2) of the local concentration changes (α, β).

[0048] Then, by touching any desired portion of the specific display sections (D1 to D4) with a finger and sliding it left or right, the start time (R1, W1) or end time (R2, W2) can be arbitrarily changed using the change operation section 19. The recirculation detection section 17 detects recirculated blood based on the changed start time (R1, W1) or end time (R2, W2) and calculates the proportion of recirculated blood (recirculation rate). The proportions of recirculated blood (recirculation rates) before and after the change calculated by the recirculation detection section 17 can be displayed on the display section 18, allowing medical professionals such as doctors to perform simulations.

[0049] Next, the control of the change operation by the change operation unit 19 will be described with reference to the flowchart shown in Fig. 6. In the measurement step S4, after the measurement result is displayed in S1a (specific display units (D1 to D4) are displayed at the display positions of the start time (R1, W1) and end time (R2, W2) of the local concentration change (α, β)), the process proceeds to S2a, where it is determined whether or not a change operation has been performed by the change operation unit 19, subject to an input operation by the instruction input unit SW2.

[0050] If it is determined in S2a that a change operation has been performed by the change operation unit 19, the process proceeds to S3a, where the start time (R1, W1) or end time (R2, W2) is changed as desired based on the change operation performed by the change operation unit 19. Thereafter, the process proceeds to S4a, where the recirculation detection unit 17 detects recirculated blood based on the changed start time (R1, W1) or end time (R2, W2), and calculates the proportion of recirculated blood (recirculation rate).

[0051] If it is determined in S2a that no change has been made by the change operation unit 19, the process skips S3a and proceeds to S4a, where the recirculation detection unit 17 detects recirculated blood based on the start time (R1, W1) or the end time (R2, W2) and calculates the proportion of recirculated blood (recirculation rate). After the recirculation rate (recirculation rate) has been calculated in S4a, the measurement process ends, provided that the operator operates the switch input unit SW1.

[0052] According to this embodiment, the recirculation detection unit 17 identifies the start point (R1, W1) or end point (R2, W2) of the local concentration change (α, β) detected by the first detection unit 5a and the second detection unit 5b, and has a change operation unit 19 that arbitrarily changes the identified start point (R1, W1) and end point (R2, W2). Therefore, an operator such as a medical professional can arbitrarily identify the start point (R1, W1) or end point (R2, W2) of the local concentration change (α, β), and can simulate the calculation of the ratio of recirculated blood.

[0053] Although the present embodiment has been described above, the present invention is not limited to this, and for example, the characteristic change imparting unit is not limited to being composed of the air vent line 13 and the solenoid valve 14, and other means may be used as long as they can impart a local concentration change with a unique peak. Furthermore, although the characteristic change imparting unit according to the present embodiment locally changes the blood concentration by concentrating the blood through water removal, the blood may also be locally changed in concentration by diluting it, for example, by introducing a replacement fluid (dialysis fluid) such as a replacement fluid into the blood circuit.

[0054] Furthermore, the first and second detectors 5a and 5b may be configured with a sensor other than a hematocrit sensor (e.g., a sensor for detecting hemoglobin concentration or a sensor for detecting protein concentration) as long as it can detect a change in blood concentration resulting in the formation of a specific peak. Furthermore, the first and second detectors 5a and 5b may be disposed at any location in the arterial and venous blood circuits 1a and 1b, respectively.

[0055] Furthermore, although the change in blood characteristics in this embodiment is a change in blood concentration, it may also be a change in other characteristics, such as a change in blood temperature. For example, it may be possible to use ultrasound, inject a marker (saline solution or microbubbles) into the blood flow, measure the dilution curve using an ultrasound probe, and capture the change in blood flow in the blood circuit in real time, thereby making it possible to quantify the recirculation rate.

[0056] Other examples include a method for evaluating recirculation by injecting a dye into an arterial blood circuit and measuring absorbance in a venous blood circuit, a method for injecting cooled saline into a blood circuit and measuring changes in blood temperature, and calculating the recirculation rate from the rate of temperature change using temperature sensors placed in the arterial and venous blood circuits, a method using electrical impedance to measure changes in the electrical impedance of blood in the blood circuit and analyze changes in blood flow, and calculating impedance changes due to recirculation using the conductivity of saline, and an optical method using infrared spectroscopy (NIRS) to measure changes in blood oxygen saturation and hemoglobin concentration, and evaluating the effects of recirculation by comparing data from the arterial and venous blood circuits.

[0057] The first embodiment of the present invention is a blood purification device that circulates a patient's blood extracorporeally through a blood circuit 1 having an arterial blood circuit 1a and a venous blood circuit 1b, and purifies the blood. The blood purification device includes a characteristic change imparting unit (an air-opening line 13 and an electromagnetic valve 14) that can impart a local concentration change in which a peak specific to the concentration change of the blood circulating extracorporeally through the blood circuit 1 is formed, a first detection unit 5a and a second detection unit 5b that are attached to the arterial blood circuit 1a and the venous blood circuit 1b, respectively, and that detect the local concentration changes α and β imparted by the characteristic change imparting unit, and a detection unit 5c that detects the local concentration changes detected by the first detection unit 5a. The apparatus further includes a recirculation detection unit 17 that detects recirculated blood, which is blood returned from the venous blood circuit 1b to the patient and then introduced back into the arterial blood circuit 1a, based on the concentration change β and the local concentration change α detected by the second detection unit 5b, and calculates the proportion of recirculated blood. The recirculation detection unit 17 identifies the start time (R1, W1) or end time (R2, W2) of the local concentration change (α, β) detected by the first detection unit 5a and the second detection unit 5b, and includes a change operation unit 19 that arbitrarily changes the identified start time (R1, W1) and end time (R2, W2). This allows an operator, such as a medical professional, to arbitrarily identify the start time (R1, W1) or end time (R2, W2) of the local concentration change (α, β), and allows for simulation of calculation of the proportion of recirculated blood.

[0058] In a second embodiment of the present invention, in the first embodiment, the recirculation detection unit 17 calculates the proportion of recirculated blood based on the local concentration change (α, β) from the start time (R1, W1) to the end time (R2, W2) arbitrarily changed by the change operation unit 19. This makes it possible to recalculate and update the proportion of recirculated blood based on the local concentration change (α, β) from the start time (R1, W1) to the end time (R2, W2) arbitrarily changed by the change operation unit 19.

[0059] A third embodiment of the present invention is similar to the first embodiment, except that the display unit 18 displays a graph of the local concentration changes (α, β) detected by the first detection unit 5a and the second detection unit 5b, and specific display sections (D1-D4) are displayed to specify the start time (R1, W1) or end time (R2, W2) of the local concentration changes (α, β) displayed in the graph on the display unit 18. The change operation section 19 allows an operator to change the start time (R1, W1) and end time (R2, W2) by arbitrarily operating the specific display sections (D1-D4). This allows the operator to easily change the start time (R1, W1) or end time (R2, W2).

[0060] In a fourth embodiment of the present invention, the start time (R1, W1) and end time (R2, W2) are changed by the change operation unit 19 by moving the position of the specific display unit (D1 to D4) displayed on the display unit 18 in the third embodiment. This allows the change operation of the start time (R1, W1) or end time (R2, W2) to be performed intuitively.

[0061] In a fifth embodiment of the present invention, in the first embodiment, the blood characteristic is blood concentration, thereby detecting recirculating blood based on changes in blood concentration and calculating the proportion of recirculating blood.

[0062] The present invention can also be applied to devices with different external shapes or devices with additional functions, provided that they have the same gist as the present invention.

[0063] 1 Blood circuit 1a Arterial blood circuit 1b Venous blood circuit 2 Dialyzer (blood purification section) 3 Blood pump 4a, 4b Air trap chamber 5a First detection section 5b Second detection section 6 Dialysis device main body 7 Dialysis fluid introduction line 8 Dialysis fluid discharge line 9 Bypass line 10 Water removal pump 11 Pressure pump 12 Air bubble separation chamber 13 Atmospheric release line 14 Solenoid valve 15 Infusion fluid pump 16 Control section 17 Recirculation detection section 18 Display section 19 Change operation section C Duplex pump La Supply line La1 Pre-infusion fluid supply line La2 Post-infusion fluid supply line D1 to D4 Specific display section SW1 Switching input section SW2 Instruction input section

Claims

1. A blood purification device that purifies a patient's blood by circulating it extracorporeally through a blood circuit having an arterial blood circuit and a venous blood circuit, comprising: a characteristic change imparting unit that can impart a local characteristic change with a peak that is specific to the characteristic change of the blood circulating extracorporeally through the blood circuit; a first detection unit and a second detection unit that are attached to the arterial blood circuit and the venous blood circuit, respectively, and detect the local characteristic change imparted by the characteristic change imparting unit; a recirculation detection unit that detects recirculated blood, which is blood returned to the patient from the venous blood circuit and is guided back into the arterial blood circuit based on the local characteristic change detected by the first detection unit and the local characteristic change detected by the second detection unit, and calculates the ratio of the recirculated blood; and a blood purification device that has a change operation unit that identifies the start or end point of the local characteristic change detected by the recirculation detection unit and arbitrarily changes the identified start and end points.

2. The blood purification device according to claim 1, wherein the recirculation detection unit calculates the proportion of recirculated blood based on local characteristic changes from the start time to the end time, which are arbitrarily changed by the change operation unit.

3. A blood purification device as described in claim 1, further comprising a display unit that displays a graph of the local characteristic changes detected by the first and second detection units, a specific display unit that specifies the start or end point of the local characteristic change displayed in the graph on the display unit, and a change operation unit that allows the operator to change the start and end points by operating the specific display unit as desired.

4. The blood purification apparatus according to claim 3, wherein the change operation unit changes the start and end times by moving the position of the specific display unit displayed on the display unit.

5. The blood purification device according to claim 1, wherein the blood characteristic is blood concentration.

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