WO2025173750A1 - Blood purification device - Google Patents

Abstract

Provided is a blood purification device capable of calculating a proportion of recirculated blood with high accuracy by accurately detecting a start point of time of at least a local characteristic change.　The present invention is provided with: a characteristic change imparting unit that can impart a local concentration change in which a peak specific to concentration changes in blood circulating extracorporeally in a blood circuit 1 is formed; a first detection unit 5a and a second detection unit 5b that detect the local concentration change imparted by the characteristic change imparting unit; and a recirculation detection unit 17 that detects recirculating blood on the basis of a local concentration change β detected by the first detection unit 5a and a local concentration change α detected by the second detection unit 5b, and that calculates the proportion of recirculating blood. The recirculation detection unit 17 detects a noise waveform γ detected immediately before detection of the local concentration changes and identifies a start time point R1 of the local concentration change α on the basis of the noise waveform γ.

Description

Blood purification device

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.

Generally, in blood purification therapies, such as hemodialysis, a patient's blood is circulated extracorporeally through a blood circuit, and purified 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 surgery) to perform extracorporeal circulation, blood that has been purified and returned to the patient's body through the venous puncture needle can sometimes become recirculated blood, where the purified blood is introduced back into the blood circuit through the arterial puncture needle without passing through the patient's organs. When this recirculation occurs, the purified blood must be further circulated extracorporeally, which reduces the amount of blood that needs to be purified that is circulating extracorporeally, resulting in a problem of reduced blood purification efficiency.

In order to detect such recirculated blood, as disclosed in Patent Document 1, for example, a dialysis machine has been proposed that operates a water removal pump to give a specific peak to the change in concentration of blood circulating extracorporeally, and uses this as a marker to detect blood recirculation. According to the dialysis machine disclosed in this document, a sensor that detects blood concentration (a sensor that detects hemoglobin concentration) is placed in the arterial blood circuit, and blood recirculation during dialysis treatment can be detected by detecting the specific peak with this sensor.

Special Publication No. 2000-502940

However, in conventional blood purification devices, when calculating the proportion of recirculated blood to determine the recirculation rate or the flow rate of the patient's shunt, the following problems arise.
When a local concentration change is applied, the detected local concentration change may vary depending on the patient's condition, the treatment environment, etc., and in order to accurately calculate the proportion of recirculated blood, it is necessary to accurately grasp the start and end points of the local concentration change. Therefore, the present applicant has conducted extensive research to accurately detect at least the start point of the local concentration change in order to accurately calculate the proportion of recirculated blood. Similar issues also exist when calculating the proportion of recirculated blood based on changes in other blood characteristics, such as blood temperature, instead of blood concentration. Here, the blood characteristics are not limited to blood concentration but include general blood characteristics, such as blood temperature.

The present invention was made in consideration of these circumstances, and aims to provide a blood purification device that can accurately calculate the proportion of recirculated blood by accurately detecting at least the start or end point of a local characteristic change.

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 includes: 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; and a recirculation detection unit that detects recirculated blood, which is blood returned to the patient from the venous blood circuit and then 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 proportion of recirculated blood. The recirculation detection unit detects a noise waveform detected immediately before the local characteristic change is detected, and identifies the start point of the local characteristic change based on the noise waveform.

Another 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 includes a characteristic change imparting unit that can impart a local characteristic change in which a peak specific to the characteristic change of the blood circulating extracorporeally through the blood circuit is formed; 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; and a recirculation detection unit that detects recirculated blood, which is blood returned to the patient from the venous blood circuit and then 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 proportion of recirculated blood.The recirculation detection unit sequentially searches back to the start of detection of the local characteristic change, using the time when a specific peak in the local characteristic change was detected as a reference, and identifies the time when the characteristic change changed from a decrease to an increase as the start of the local characteristic change.

Furthermore, another 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 includes a characteristic change imparting unit that can impart a local characteristic change in which a peak 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; and a recirculation detection unit that detects recirculated blood, in which blood returned from the venous blood circuit is guided back into the arterial blood circuit and flows, 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 proportion of recirculated blood. The recirculation detection unit detects the amount of change in the local characteristic change over time or with the cumulative blood flow rate after the specific peak is detected, and identifies the point at which the amount of change changes from a decrease to an increase as the end point of the local characteristic change.

According to the present invention, the proportion of recirculating blood can be calculated with high accuracy by accurately detecting at least the start or end point of a local characteristic change.

1 is a 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 FIG. 1 is a 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. A flowchart showing the control performed by the control unit of the blood purification device. 1 is a flowchart showing the control content during the measurement process by the recirculation detection unit of the blood purification device according to the first embodiment of the present invention. Graph illustrating the measurement process by the recirculation detection unit 10 is a flowchart showing the control process performed by the recirculation detection unit of the blood purification device according to the second embodiment of the present invention during the measurement process. Graph illustrating the measurement process by the recirculation detection unit 10 is a flowchart showing the control content during the measurement process by the recirculation detection unit of the blood purification device according to the third embodiment of the present invention. Graph illustrating the measurement process by the recirculation detection unit 10 is a flowchart showing the control content during the measurement process by the recirculation detection unit of the blood purification device according to the fourth embodiment of the present invention. Graph illustrating the measurement process by the recirculation detection unit 10 is a flowchart showing the control content during the measurement process by the recirculation detection unit of the blood purification device according to the fifth embodiment of the present invention. Graph illustrating the measurement process by the recirculation detection unit

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 is configured to include a dialysis device main body 6 that supplies dialysate to the dialyzer 2 while removing water from the dialyzer 2, a control unit 16, a recirculation detection unit 17, and a display unit 18 disposed in the dialysis device main body 6.

As shown in the diagram, the blood circuit 1 is primarily 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 detection unit 5a are disposed along the way. Meanwhile, a venous puncture needle b is connected to the tip of the venous blood circuit 1b, and a second detection unit 5b and a debubbling air trap chamber 4b are connected along the way.

Then, 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 and reaches the dialyzer 2 while being debubbled in the air trap chamber 4a. After being purified by the dialyzer 2, the patient's blood passes through the venous blood circuit 1b while being debubbled in the air trap chamber 4b and returns to the patient's body. In this way, the patient's blood can be circulated extracorporeally through the blood circuit 1 while being purified by the dialyzer 2.

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

The dialyzer 2 contains multiple 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 numerous tiny pores that penetrate from their outer circumferential surface to their inner circumferential surface, forming hollow fiber membranes that allow impurities in the blood to pass through into the dialysate.

Meanwhile, the dialysis device main body 6 is composed of a duplex pump C, a bypass line 9 connected to the dialysate discharge line 8, bypassing the drain side Cb of the duplex pump C, a water removal pump 10 connected to the bypass line 9, a pressure pump 11 that flows the dialysate from the dialyzer 2 to the drain side Cb of the duplex pump C, a bubble separation chamber 12, an atmospheric vent line 13, and a solenoid valve 14.

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. Specifically, the duplex pump C is a metering pump with approximately equal volumes on the supply side Ca and the drain side Cb, 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 remains sealed) when the solenoid valve 14 is closed.

The pressure pump 11 is connected between the dialyzer 2 and the duplex pump C in the dialysate discharge line 8, and is used to flow the dialysate from the dialyzer 2 to the duplex pump C. It 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, just like the pressure pump 11.

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. Furthermore, 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 a drainage means (not shown). After the dialysate supplied from the dialysate supply device reaches the dialyzer 2 through the dialysate inlet line 7, it is sent to the drainage means through the dialysate outlet line 8 and bypass line 9.

The ultrafiltration pump 10 is used to remove water from the patient's blood flowing through the dialyzer 2. In other words, because the duplex pump C is a fixed-volume type, when the ultrafiltration pump 10 is driven, the volume of liquid discharged from the dialysate discharge line 8 is greater than the volume of dialysate introduced from the dialysate inlet line 7, and water is removed from the blood in an amount equal to the greater volume.

The bubble separation chamber 12 is what is commonly called a degassing chamber, and is of a specified capacity connected between the pressure pump 11 and the duplex pump C in the dialysis fluid discharge line 8, and is configured to capture bubbles in the dialysis fluid. Extending from this bubble separation chamber 12 are the bypass line 9 mentioned above, as well as an atmosphere vent line 13. The tip of this atmosphere vent line 13 is open to the atmosphere, and a solenoid valve 14 serving as a valve means is connected midway through the line.

The solenoid valve 14 can be opened and closed to open or close the atmosphere release line 13. When open, the bubble separation chamber 12 is in communication with the outside air, and when closed, the bubble separation chamber 12 is isolated from the outside air. Before or after dialysis treatment, the solenoid valve 14 can be operated to open the atmosphere release line 13, allowing the bubbles trapped in the bubble separation chamber 12 to be released into the atmosphere.

In addition, a supply line La is connected to the dialysate introduction line 7 in this embodiment. This 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, while 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.

A fluid replacement pump 15, which is a peristaltic pump similar to the blood pump 3, is provided on this supply line La. During 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 to the venous blood circuit 1b via the post-fluid replacement supply line La2, enabling post-fluid replacement.

In this embodiment, the atmosphere vent line 13 and solenoid valve 14 constitute the characteristic change imparting unit of the present invention, and by operating the solenoid valve 14 to open the atmosphere vent line 13, a local concentration change (characteristic change) with a unique peak can be imparted to the blood flowing through the dialyzer 2 by rapid and short-term concentration. In other words, during dialysis treatment, when the solenoid valve 14 is operated to open the closed atmosphere vent line 13, the outlet pressure of the pressure pump 11 becomes approximately equal to atmospheric pressure, and a momentary high negative pressure is generated upstream of the pressure pump 11, causing rapid and short-term water removal (hemoconcentration) of the blood flowing through the dialyzer 2 (blood flow path).

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 creates a unique peak in the change in blood concentration (hematocrit value). The solenoid valve 14 opens the atmosphere vent line 13 for a short time (in this embodiment, the opening of the atmosphere vent line 13 can be set to any time 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.

The time that the solenoid valve 14 opens the atmospheric 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, dialysis fluid pressure, etc.). In this invention, "sudden and short-term" refers to a magnitude and duration that allows the applied pulse to be confirmed after passing through the circuit, and "unique" refers to a fluctuation pattern that can be distinguished from fluctuations caused by other factors such as pump fluctuations or patient movement.

The first and second detectors 5a and 5b are disposed in the arterial and venous blood circuits 1a and 1b, respectively, and detect the concentration (specifically, the hematocrit value) of the blood flowing through these channels. The first and second detectors 5a and 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 light onto the blood from the light-emitting element and receiving the transmitted or reflected light with the light-receiving element.

Specifically, the first detection unit 5a and the second detection unit 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 characteristics, and this property can be used to electro-optically quantify the red blood cells required to measure the hematocrit value, thereby determining the hematocrit value. However, near-infrared light emitted from the light-emitting element is affected by absorption and scattering when it enters the blood and is received by the light-receiving element. The hematocrit value can then be calculated by analyzing the light absorption and scattering rate from the intensity of the received light.

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

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 extracts 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 drug solutions such as heparin into the blood circuit 1, as well as solenoid valves such as solenoid valve 14 that can impart localized concentration changes that form peaks specific to changes in blood concentration, and is capable of controlling these pumps and solenoid valves.

Furthermore, as shown in FIG. 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. Such 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.

Furthermore, the first detection unit 5a and second detection unit 5b in this embodiment are electrically connected to a recirculation detection unit 17 arranged in the dialysis device main body 6, and the recirculation detection unit 17 is electrically connected to a display unit 18 consisting of a touch panel. The display unit 18 displays a graph of the local concentration changes α and β detected by the first detection unit 5a and second detection unit 5b, and in addition to this graph display, it is also capable of displaying the ratio of recirculated blood calculated by the recirculation detection unit 17 as a numerical value, etc.

Furthermore, as shown in FIG. 2, the display unit 18 according to this embodiment is connected to the switching input unit SW1, and can be switched and input by the operator operating the switching input unit SW1. Such instruction input unit SW2 can be anything that the operator can operate and input at any time, and may be, for example, a switch unit displayed on a touch panel (including the display unit 18), or a mechanical switch.

The recirculation detection unit 17 is configured, for example, by 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 in this embodiment is configured to include a monitoring unit 17a, a graph creation unit 17b, a calculation unit 17c, and a memory unit 17d.

The monitoring unit 17a monitors 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.

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

Rrec (%)=S2/S1×100

The proportion of recirculated blood (recirculation rate) Rrec calculated in this manner is displayed on the display unit 18 so that it can be visually confirmed by doctors and other medical professionals. 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, in addition to the recirculation rate, the display unit 18 in this embodiment is capable of graphically displaying the local concentration changes detected by the first detection unit 5a and the second detection unit 5b, as shown in Figure 4, and is able to display the local concentration change α where the characteristic peak P1 is formed and the local concentration change β where the characteristic peak P2 is formed, each as a curve graph.

Meanwhile, the recirculation detection unit 17 creates a graph showing local concentration changes α and β, with the horizontal axis representing elapsed time (cumulative flow rate or time) and the vertical axis representing blood concentration (hematocrit value), as shown in Figure 4, based on the blood concentration detected by the first detection unit 5a and the second detection unit 5b, and monitors the changes in blood concentration at a predetermined interval (e.g., 0.1 second interval). This makes it possible 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.

As shown in FIG. 7, the recirculation detection unit 17 according to this embodiment is configured to detect a noise waveform γ detected immediately before a local concentration change α is detected, and to identify the start time point R1 of the local concentration change α based on the noise waveform γ. This noise waveform γ is generated as a precursor noise of the local concentration change α detected by the second detection unit 5b when the solenoid valve 14 constituting the characteristic change imparting unit is changed from a closed state to an open state to impart a local concentration change.

Specifically, after detecting peak P3 of the noise waveform γ, the recirculation detection unit 17 identifies the point in time when the concentration change changes from a decrease to an increase as the start point R1 of the local concentration change α. For example, the maximum or minimum value of the detected blood concentration value is updated sequentially at each predetermined cycle, and the concentration change is considered to have decreased when the blood concentration value decreases from the maximum value, and to have increased when the blood concentration value increases from the minimum value.

Furthermore, for example, the recirculation detection unit 17 can sequentially detect the slope or area for each predetermined period in a graph showing changes in concentration over time or with the cumulative blood flow rate, and can detect decreases (a downward trend to the right in the graph) and increases (an upward trend to the right in the graph) in concentration changes based on the detected changes in slope or area.

The peaks of the waveforms in the graph (peak P1 characteristic of local concentration change α, peak P2 characteristic of local concentration change β, and peak P3 of noise waveform γ) can be found by calculating the maximum value of each waveform. The slope for each predetermined cycle can be found using a calculation method such as the least squares method for the curve within the cycle, and the area for each predetermined cycle can be found using a calculation method such as integration for the curve within the cycle.

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, pressure pump 11, fluid replacement pump 15, drug injection pump, etc.) to measurement parameters that are different from those used during the treatment process in which blood purification treatment is performed. This measurement process will be explained based on the flowchart in Figure 5.

First, the measurement process begins 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 the measurement parameters and drives the pump based on those measurement parameters. Then, in S2, the system waits until the blood concentration detected by the first detection unit 5a and the second detection unit 5b stabilizes. These measurement parameters consist of parameters that slow the drive speed of the pump (the pump to be controlled) down from that during the treatment process or stop the pump. Then, upon input operation of the command input unit SW2 by the operator, the system proceeds to S3, where the solenoid valve 14 is operated to open the atmosphere vent line 13, thereby creating localized concentration changes with characteristic peaks P1 and P2.

Then, the process proceeds to S4, where the recirculation detection unit 17 detects recirculated blood and calculates the proportion of recirculated blood (recirculation rate) 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. 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. Then, after the recirculated blood has been detected and the proportion of recirculated blood (recirculation rate) calculated, the process proceeds to S5, where the control unit 16 reverts from measurement parameters to treatment parameters, provided that the operator operates the switch input unit SW1. This completes the measurement process, and blood purification treatment can be performed based on the treatment parameters.

Next, the specific control contents of the recirculation detection unit 17 in the measurement S4 of the measurement step will be described with reference to the flowchart of FIG.
5, after the local concentration change is applied in S3, the recirculation detection unit 17 detects the noise waveform γ in Sa1, and when the noise waveform γ is detected, the end of the noise waveform γ is detected in Sa2. The end of the noise waveform γ can be found by detecting the peak P3 of the noise waveform γ and detecting the point in time from peak P3 when the concentration change changes from a decrease to an increase, and this end can be taken as the start point R1 of the local concentration change α.

Then, proceed to Sa3, and based on 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, the areas S1 and S2 shown in Figure 4 are calculated, and the recirculation rate (Rrec (%)), which is the proportion of recirculated blood, can be calculated from the ratio of these areas S1 and S2.

In this embodiment, the recirculation detection unit 17 detects the noise waveform γ that is detected immediately before the local concentration change α is detected, and identifies the start time R1 of the local concentration change α based on the noise waveform γ.Therefore, by using the noise waveform γ to accurately detect at least the start time R1 of the local concentration change α, the proportion of recirculated blood can be calculated with high accuracy.

Next, a blood purification apparatus according to a second embodiment of the present invention will be described.
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 comprises a blood circuit 1 connected to a dialyzer 2 as a blood purification unit, 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, and a display unit 18 disposed in the dialysis device main body 6. Note that the same components as those in the first embodiment are designated by the same reference numerals, and detailed descriptions thereof will be omitted.

As in the first embodiment, the recirculation detection unit 17 creates a graph showing local concentration changes α and β, with the horizontal axis representing elapsed time (cumulative flow rate or time) and the vertical axis representing blood concentration (hematocrit value), as shown in Figure 4, based on the blood concentration detected by the first detection unit 5a and the second detection unit 5b, and monitors the blood concentration changes at a predetermined interval (e.g., 0.1 second interval). This makes it possible 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.

The recirculation detection unit 17 in this embodiment is configured, for example, with 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).

In particular, as shown in Figure 9, the recirculation detection unit 17 of this embodiment is configured to use the time when a specific peak P1 in the local concentration change α is detected as a reference point and sequentially search back to the start of detection of the local concentration change α (i.e., search in the direction f from the time of the specific peak P1 in Figure 9), and identify the time when the concentration change changes from a decrease to an increase as the start time R1 of the local concentration change α.

Note that the waveform peaks in the graph (peak P1 characteristic of local concentration change α, peak P2 characteristic of local concentration change β, and peak P3 of noise waveform γ) can be found by calculating the maximum value of each waveform, as in the first embodiment. Also, the slope for each predetermined cycle can be found using a calculation method such as the least squares method for the curve within the cycle, as in the first embodiment, and the area for each predetermined cycle can be found using a calculation method such as integration for the curve within the cycle.

However, in this embodiment, as in the first 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 controls the pumps to be controlled (duplex pump C, blood pump 3, water removal pump 10, pressure pump 11, fluid replacement pump 15, drug injection pump, etc.) by changing the parameters for driving them to measurement parameters that are different from those used during the treatment process in which blood purification treatment is performed. This measurement process is as described in the first embodiment based on the flowchart in Figure 5.

Next, the specific control contents by the recirculation detection unit 17 in the measurement S4 (see FIG. 5) of the measurement step will be described with reference to the flowchart of FIG.
5, after the local concentration change is given in S3, in Sb1, a specific peak P1 of the local concentration change α is detected by the recirculation detection unit 17. Then, after the specific peak P1 is detected, the process proceeds to Sb2, where, using the time point at which the specific peak P1 was detected as a reference, a sequential search is performed (sequential search in the direction f) going back to the start of detection of the local concentration change α, and the time point at which the concentration change changes from decreasing to increasing can be determined as the start time R1 of the local concentration change α.

Then, proceeding to Sb3, the areas S1 and S2 shown in Figure 4 are calculated based on 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 the recirculation rate (Rrec (%)), which is the proportion of recirculated blood, can be calculated from the ratio of these areas S1 and S2.

In this embodiment, the recirculation detection unit 17 uses the time when a specific peak P1 in the local concentration change α is detected as a reference point and sequentially searches back to the start of detection of the local concentration change α, identifying the time when the concentration change changes from a decrease to an increase as the start time R1 of the local concentration change α.Therefore, by using the specific peak P1 to accurately detect at least the start time R1 of the local concentration change α, the proportion of recirculated blood can be calculated with high precision.

Next, a blood purification apparatus according to a third embodiment of the present invention will be described.
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 comprises a blood circuit 1 connected to a dialyzer 2 as a blood purification unit, 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, and a display unit 18 disposed in the dialysis device main body 6. Note that the same components as those in the first embodiment are designated by the same reference numerals, and detailed descriptions thereof will be omitted.

As in the first embodiment, the recirculation detection unit 17 creates a graph showing local concentration changes α and β, with the horizontal axis representing elapsed time (cumulative flow rate or time) and the vertical axis representing blood concentration (hematocrit value), as shown in Figure 4, based on the blood concentration detected by the first detection unit 5a and the second detection unit 5b, and monitors the blood concentration changes at a predetermined interval (e.g., 0.1 second interval). This makes it possible 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.

Here, as shown in FIG. 11, the recirculation detection unit 17 according to this embodiment is configured to detect the amount of change in the local concentration change α over time or with the cumulative blood flow rate after the characteristic peak P1 is detected, and identify the point at which the amount of change changes from a decrease to an increase as the end point R2 of the local concentration change α. Specifically, the recirculation detection unit 17 sequentially (every cycle in this embodiment) calculates the value of the blood concentration on the graph after the characteristic peak P1 in the local concentration change α is detected, and identifies the point at which the calculated value of the blood concentration on the graph reaches a minimum as the end point R2.

For example, the recirculation detection unit 17 can sequentially calculate the blood concentration value on the graph for each period after the characteristic peak P1 in the local concentration change α is detected, and identify the position where the calculated blood concentration value on the graph changes from a decrease to an increase as the minimum value. Furthermore, if the blood concentration value does not change from a decrease to an increase and remains constant (if the graph is flat), the position where the blood concentration value first changes to a constant value can be identified as the minimum value. Furthermore, if the blood concentration value continues to decrease, the measurement end position can be identified as the minimum value. The peaks of the waveforms in the graph (the characteristic peak P1 of the local concentration change α and the characteristic peak P2 of the local concentration change β) can be found by calculating the maximum value of each waveform.

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 controls the pumps to be controlled (duplex pump C, blood pump 3, water removal pump 10, pressure pump 11, fluid replacement pump 15, drug injection pump, etc.) by changing the parameters for driving them to measurement parameters that are different from those used during the treatment process in which blood purification treatment is performed. This measurement process is the same as in the first embodiment, and will be described based on the flowchart in Figure 5.

First, when the measurement process is initiated upon operation of the switch input unit SW1 by the operator, the control unit 16 temporarily changes the parameters of the pump to be controlled to measurement parameters in S1 and drives the pump based on those measurement parameters. Then, in S2, the system waits until the blood concentration detected by the first detection unit 5a and the second detection unit 5b stabilizes. These measurement parameters consist of parameters that slow or stop the drive speed of the pump (the pump to be controlled) from that during the treatment process. Then, upon operation of the instruction input unit SW2 by the operator, the system proceeds to S3, where the solenoid valve 14 is operated to open the atmosphere vent line 13, thereby creating localized concentration changes that form characteristic peaks P1 and P2.

Then, the process proceeds to S4, where the recirculation detection unit 17 detects recirculated blood and calculates the proportion of recirculated blood (recirculation rate) 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. After the recirculated blood has been detected and the proportion of recirculated blood (recirculation rate) calculated, the process proceeds to S5, where the control unit 16 reverts from measurement parameters to treatment parameters, provided that the operator operates the switch input unit SW1. This completes the measurement process, and blood purification treatment can be performed based on the treatment parameters.

Next, the specific control contents of the recirculation detection unit 17 in the measurement S4 of the measurement process will be described with reference to the flowchart of FIG.
5, after the local concentration change is given in S3, the recirculation detection unit 17 detects the characteristic peak P1 of the local concentration change α in Sc1. When the characteristic peak P1 is detected, the minimum value of the concentration after the detection of the characteristic peak P1 is detected in Sc2. This minimum value can be obtained by sequentially calculating the value of the blood concentration on the graph after the characteristic peak P1 of the local concentration change α is detected, and the point at which the calculated value of the blood concentration on the graph reaches the minimum can be identified as the end point R2.

Then, proceed to Sc3, and based on 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, the areas S1 and S2 shown in Figure 4 are calculated, and the recirculation rate (Rrec (%)), which is the proportion of recirculated blood, can be calculated from the ratio of these areas S1 and S2.

In this embodiment, the recirculation detection unit 17 sequentially calculates the blood concentration value on the graph after the characteristic peak P1 in the local concentration change α is detected, and identifies the point at which the calculated blood concentration value on the graph reaches its minimum as the end point R2.Therefore, by determining the minimum value of the blood concentration after the characteristic peak P1 and accurately detecting at least the end point R2 of the local concentration change α, the proportion of recirculated blood can be calculated with high precision.

Next, a blood purification apparatus according to a fourth embodiment of the present invention will be described.
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 comprises a blood circuit 1 connected to a dialyzer 2 as a blood purification unit, 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, and a display unit 18 disposed in the dialysis device main body 6. Note that the same components as those in the first embodiment are designated by the same reference numerals, and detailed descriptions thereof will be omitted.

As in the first embodiment, the recirculation detection unit 17 creates a graph showing local concentration changes α and β, with the horizontal axis representing elapsed time (cumulative flow rate or time) and the vertical axis representing blood concentration (hematocrit value), as shown in Figure 4, based on the blood concentration detected by the first detection unit 5a and the second detection unit 5b, and monitors the blood concentration changes at a predetermined interval (e.g., 0.1 second interval). This makes it possible 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.

The recirculation detection unit 17 in this embodiment is configured, for example, with 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).

In particular, the recirculation detection unit 17 according to this embodiment is configured to sequentially (for each cycle in this embodiment) calculate the slope of the graph (the slope of the line m connecting two points in the figure) after the characteristic peak P1 in the local concentration change α is detected, as shown in FIG. 13, and identify the point at which the calculated slope of the graph becomes horizontal (slope is 0) as the end point R2. Note that the waveform peaks in the graph (the characteristic peak P1 of the local concentration change α and the characteristic peak P2 of the local concentration change β) can be found by calculating the maximum value of each waveform, as in the first embodiment. Furthermore, the slope for each predetermined cycle can be found using a calculation method such as the least squares method on the curve within the cycle.

However, in this embodiment, as in the first 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 controls the pumps to be controlled (duplex pump C, blood pump 3, water removal pump 10, pressure pump 11, fluid replacement pump 15, drug injection pump, etc.) by changing the parameters for driving them to measurement parameters that are different from those used during the treatment process in which blood purification treatment is performed. This measurement process is as described in the first embodiment based on the flowchart in Figure 5.

Next, the specific control contents by the recirculation detection unit 17 in measurement S4 (see FIG. 5) of the measurement step will be described with reference to the flowchart of FIG.
5, after the local concentration change is given in S3, in Sd1, a specific peak P1 of the local concentration change α is detected by the recirculation detection unit 17. Then, after the specific peak P1 is detected, the process proceeds to Sd2, where the slope of the graph after the specific peak P1 is detected is calculated sequentially, and the point in time when the calculated slope of the graph becomes horizontal (slope is 0) is identified as the end point R2.

Then, proceed to Sd3, and based on 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, the areas S1 and S2 shown in Figure 4 are calculated, and the recirculation rate (Rrec (%)), which is the proportion of recirculated blood, can be calculated from the ratio of these areas S1 and S2.

In this embodiment, the recirculation detection unit 17 sequentially calculates the slope of the graph after the characteristic peak P1 in the local concentration change α is detected, and identifies the point in time at which the calculated slope of the graph becomes horizontal as the end point R2.Therefore, by determining the slope of the graph after the characteristic peak P1 and accurately detecting at least the end point R2 of the local concentration change α, the proportion of recirculated blood can be calculated with high accuracy.

Next, a blood purification apparatus according to a fifth embodiment of the present invention will be described.
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 comprises a blood circuit 1 connected to a dialyzer 2 as a blood purification unit, 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, and a display unit 18 disposed in the dialysis device main body 6. Note that the same components as those in the first embodiment are designated by the same reference numerals, and detailed descriptions thereof will be omitted.

As in the first embodiment, the recirculation detection unit 17 creates a graph showing local concentration changes α and β, with the horizontal axis representing elapsed time (cumulative flow rate or time) and the vertical axis representing blood concentration (hematocrit value), as shown in Figure 5, based on the blood concentration detected by the first detection unit 5a and the second detection unit 5b, and monitors the changes in blood concentration at a predetermined interval (e.g., 0.1 second interval). This makes it possible 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.

The recirculation detection unit 17 in this embodiment is configured, for example, with 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).

In particular, the recirculation detection unit 17 according to this embodiment is configured to sequentially (for each cycle in this embodiment) calculate the area of the graph (the area Sn of the region between two points in the figure) after the characteristic peak P1 of the local concentration change α is detected, as shown in FIG. 15, and identify the point at which the rate of change of the calculated area of the graph decreases as the end point R2. Note that the waveform peaks in the graph (the characteristic peak P1 of the local concentration change α and the characteristic peak P2 of the local concentration change β) can be found by calculating the maximum value of each waveform, as in the first embodiment. Furthermore, the area for each predetermined cycle can be found using an arithmetic method such as integration on the curve within the cycle.

However, in this embodiment, as in the first 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 controls the pumps to be controlled (duplex pump C, blood pump 3, water removal pump 10, pressure pump 11, fluid replacement pump 15, etc.) by changing the parameters for driving them to measurement parameters that are different from those used during the treatment process in which blood purification treatment is performed. This measurement process is as described in the first embodiment based on the flowchart in Figure 5.

Next, the specific control contents of the recirculation detection unit 17 in measurement S4 (see FIG. 5) of the measurement step will be described with reference to the flowchart of FIG.
5, after the local concentration change is given in S3, Se1 detects a specific peak P1 of the local concentration change α by the recirculation detection unit 17. Then, after the specific peak P1 is detected, the process proceeds to Se2, where the area of the graph after the specific peak P1 is detected is calculated sequentially, and the point in time at which the rate of change of the calculated area of the graph decreases is identified as the end point R2.

Then, proceed to Se3, and based on 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, the areas S1 and S2 shown in Figure 5 are calculated, and the recirculation rate (Rrec (%)), which is the proportion of recirculated blood, can be calculated from the ratio of these areas S1 and S2.

In this embodiment, the recirculation detection unit 17 sequentially calculates the area of the graph after the characteristic peak P1 in the local concentration change α is detected, and identifies the point at which the rate of change in the calculated graph area decreases as the end point R2.Therefore, by determining the area of the graph after the characteristic peak P1 and accurately detecting at least the end point R2 of the local concentration change α, the proportion of recirculated blood can be calculated with high accuracy.

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

Furthermore, the first detector 5a and the second detector 5b may be configured with something other than a hematocrit sensor (for example, a sensor that detects hemoglobin concentration or a sensor that detects the concentration of proteins, etc.) as long as it can detect changes in blood concentration that form a unique peak. Furthermore, the first detector 5a and the second detector 5b may be disposed at any location on the arterial blood circuit 1a and the venous blood circuit 1b, respectively.

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, ultrasound may be used to inject a marker (saline or microbubbles) into the blood flow, measure the dilution curve using an ultrasound probe, and capture changes in blood flow within the blood circuit in real time, making it possible to quantify the recirculation rate.

Furthermore, it may be a method for evaluating recirculation by injecting a dye into the arterial blood circuit and measuring absorbance in the venous blood circuit, or a method for injecting cooled saline into the blood circuit and measuring changes in blood temperature, with temperature sensors placed in the arterial and venous blood circuits to calculate the recirculation rate from the rate of temperature change. Furthermore, it may be a method that uses electrical impedance to measure changes in the electrical impedance of the blood in the blood circuit and analyze changes in blood flow, and calculates impedance changes due to recirculation using the conductivity of the saline, or a method that uses optics to measure changes in blood oxygen saturation and hemoglobin concentration using near-infrared spectroscopy (NIRS), and evaluates the effects of recirculation by comparing data from the arterial and venous blood circuits.

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 device comprises a characteristic change imparting unit (air vent line 13 and solenoid valve 14) that can impart local concentration changes that form peaks specific to the concentration changes of the blood circulating extracorporeally through the blood circuit 1, and 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. The system includes a second detection unit (5b), and a recirculation detection unit (17) that detects recirculated blood, which is blood returned to the patient from the venous blood circuit (1b) and re-circulated 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 calculates the proportion of recirculated blood. The recirculation detection unit (17) detects a noise waveform (γ) detected just before the local concentration change is detected, and identifies the start time (R1) of the local concentration change (α) based on the noise waveform (γ). This allows the proportion of recirculated blood to be calculated with high accuracy by accurately detecting at least the start time (R1) of the local concentration change (α) using the noise waveform (γ).

In a second embodiment of the present invention, the recirculation detection unit 17 in the first embodiment detects peak P3 of the noise waveform γ and then identifies the point in time when the concentration change changes from a decrease to an increase as the start point R1 of the local concentration change α. This makes it possible to accurately identify the start point R1 of the local concentration change α using the noise waveform γ.

A third embodiment of the present invention is a second embodiment in which the recirculation detection unit 17 sequentially detects the slope or area for each predetermined period in a graph showing concentration changes over time or with the cumulative blood flow rate, and detects decreases and increases in concentration changes based on the detected changes in slope or area. This makes it possible to smoothly and accurately identify the start point R1 of a local concentration change α using the noise waveform γ.

A fourth 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 device comprises a characteristic change imparting unit (air vent line 13 and solenoid valve 14) that can impart local concentration changes that form peaks specific to the concentration changes in the blood circulating extracorporeally through the blood circuit 1, 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 The system is equipped with a recirculation detection unit 17 that detects recirculated blood, which is blood returned to the patient from the venous blood circuit 1b and then introduced back into the arterial blood circuit 1a, based on the detected local 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 uses the time when a specific peak P1 in the local concentration change α is detected as a reference point and sequentially searches back to the start of detection of the local concentration change α, identifying the time when the concentration change changes from a decrease to an increase as the start time R1 of the local concentration change.This allows the proportion of recirculated blood to be calculated with high accuracy by accurately detecting at least the start time R1 of the local concentration change α using the specific peak P1.

In a fifth embodiment of the present invention, in the fourth embodiment, the recirculation detection unit 17 sequentially detects the slope or area for each predetermined period in a graph showing concentration changes over time or with the cumulative blood flow rate, and detects decreases and increases in concentration changes based on the detected changes in slope or area. This makes it possible to smoothly and accurately identify the start point R1 of a local concentration change α by utilizing a specific peak P1.

A sixth 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 device comprises a characteristic change imparting unit (air vent line 13 and solenoid valve 14) that can impart local concentration changes that form peaks specific to the concentration changes in the blood circulating extracorporeally through the blood circuit 1, 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 second detection unit 5b that detects the local concentration changes α and β imparted by the characteristic change imparting unit. This blood purification device is equipped with a recirculation detection unit 17 that detects recirculated blood, where blood returned to the patient from the venous blood circuit 1b is guided back into the arterial blood circuit 1a and flows, based on the local concentration change β detected by the first detection unit 5b 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 detects the amount of change in the local concentration change α over time or with the integrated blood flow rate after the detection of the characteristic peak P1, and identifies the point at which the amount of change changes from a decrease to an increase as the end point R2 of the local concentration change α.This allows the proportion of recirculated blood to be calculated with high accuracy by accurately detecting at least the end point R2 of the local concentration change α.

In a seventh embodiment of the present invention, in the sixth embodiment, the recirculation detection unit 17 sequentially calculates the blood concentration value on the graph after a characteristic peak P1 in the local concentration change α is detected, and identifies the point in time at which the calculated blood concentration value on the graph reaches its minimum as the end point R2. This makes it possible to determine the minimum value after the characteristic peak P1 is detected, and accurately identify the end point R2 of the local concentration change α.

In an eighth embodiment of the present invention, in the sixth embodiment, the recirculation detection unit 17 sequentially calculates the slope of the graph after a characteristic peak P1 in the local concentration change α is detected, and identifies the point in time at which the calculated slope of the graph becomes horizontal as the end point R2. This makes it possible to determine the slope of the graph after the characteristic peak P1 is detected, and accurately identify the end point R2 of the local concentration change α.

A ninth embodiment of the present invention is a sixth embodiment in which the recirculation detection unit 17 sequentially calculates the area of the graph after a characteristic peak P1 in the local concentration change α is detected, and identifies the point in time at which the rate of change in the calculated graph area decreases as the end point R2. This makes it possible to determine the area of the graph after the characteristic peak P1 is detected, and accurately identify the end point R2 of the local concentration change α.

A tenth embodiment of the present invention is any one of the first, fourth, and sixth embodiments, in which the recirculation detection unit detects recirculated blood and calculates the proportion of recirculated blood in a measurement process separate from the treatment process in which blood purification treatment is performed.

An eleventh embodiment of the present invention is the tenth embodiment, further comprising a switching input unit or instruction input unit that can be operated by an operator, and the measurement process is performed as a predetermined step, conditional on input operation of the switching input unit or instruction input unit.

A twelfth embodiment of the present invention is any one of the first, fourth, and sixth embodiments, in which the blood characteristic is blood concentration. This makes it possible to detect recirculating blood based on changes in blood concentration and calculate the proportion of recirculating blood.

As long as the purpose is the same as that of the present invention, it can also be applied to products with different external shapes or with added functions.

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 unit 5b Second detection unit 6 Dialysis device main body 7 Dialysis fluid introduction line 8 Dialysis fluid discharge line 9 Bypass line 10 Water removal pump 11 Pressurizing pump 12 Air bubble separation chamber 13 Atmospheric release line 14 Solenoid valve 15 Infusion fluid pump 16 Control unit 17 Recirculation detection unit 18 Display unit C Duplex pump La Supply line La1 Pre-infusion fluid supply line La2 Post-infusion fluid supply line SW1 Switching input unit SW2 Instruction input unit

Claims (12)

A blood purification device that purifies a patient's blood by extracorporeally circulating the blood through a blood circuit having an arterial blood circuit and a venous blood circuit,
a characteristic change applying unit that applies a local characteristic change in which a peak specific to the characteristic change of blood circulating extracorporeally through the blood circuit is formed;
a first detection unit and a second detection unit attached to the arterial blood circuit and the venous blood circuit, respectively, for detecting the local characteristic change imparted by the characteristic change imparting unit;
a recirculation detection unit that detects recirculated blood, which is blood returned to a patient from the venous blood circuit and then 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 a ratio of the recirculated blood;
Equipped with
The blood purification device wherein the recirculation detection unit detects a noise waveform detected immediately before the local characteristic change is detected, and identifies the start time of the local characteristic change based on the noise waveform. The blood purification device of claim 1, wherein the recirculation detection unit, after detecting a peak in the noise waveform, identifies the point at which the characteristic change changes from a decrease to an increase as the start point of the local characteristic change. The blood purification device of claim 2, wherein the recirculation detection unit sequentially detects the slope or area for each predetermined period in a graph showing the change in the characteristic over time or with the cumulative blood flow rate, and detects decreases and increases in the change in the characteristic based on the detected changes in the slope or area. A blood purification device that purifies a patient's blood by extracorporeally circulating the blood through a blood circuit having an arterial blood circuit and a venous blood circuit,
a characteristic change applying unit that applies a local characteristic change in which a peak specific to the characteristic change of blood circulating extracorporeally through the blood circuit is formed;
a first detection unit and a second detection unit attached to the arterial blood circuit and the venous blood circuit, respectively, for detecting the local characteristic change imparted by the characteristic change imparting unit;
a recirculation detection unit that detects recirculated blood, which is blood returned to a patient from the venous blood circuit and then 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 a ratio of the recirculated blood;
Equipped with
The recirculation detection unit sequentially searches back to the start of detection of the local characteristic change, using the time when a specific peak in the local characteristic change is detected as a reference point, and identifies the time when the characteristic change changes from decreasing to increasing as the start of the local characteristic change. The blood purification device of claim 4, wherein the recirculation detection unit sequentially detects the slope or area for each predetermined period in a graph showing the change in the characteristic over time or with the cumulative blood flow rate, and detects decreases and increases in the change in the characteristic based on the detected changes in the slope or area. A blood purification device that purifies a patient's blood by extracorporeally circulating the blood through a blood circuit having an arterial blood circuit and a venous blood circuit,
a characteristic change applying unit that applies a local characteristic change in which a peak specific to the characteristic change of blood circulating extracorporeally through the blood circuit is formed;
a first detection unit and a second detection unit attached to the arterial blood circuit and the venous blood circuit, respectively, for detecting the local characteristic change imparted by the characteristic change imparting unit;
a recirculation detection unit that detects recirculated blood, which is blood returned to a patient from the venous blood circuit and then 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 a ratio of the recirculated blood;
Equipped with
The recirculation detection unit detects the amount of change in the local characteristic change over time or with the cumulative blood flow rate after the specific peak is detected, and identifies the point at which the amount of change changes from a decrease to an increase as the end point of the local characteristic change. The blood purification device of claim 6, wherein the recirculation detection unit sequentially calculates the value of the blood characteristic on the graph after a specific peak in the local characteristic change is detected, and identifies the point at which the calculated value of the blood characteristic on the graph reaches a minimum as the end point. The blood purification device of claim 6, wherein the recirculation detection unit sequentially calculates the slope of the graph after a specific peak in the local characteristic change is detected, and identifies the end point as the point at which the calculated slope of the graph becomes horizontal. The blood purification device of claim 6, wherein the recirculation detection unit sequentially calculates the area of the graph after a specific peak in the local characteristic change is detected, and identifies the point at which the rate of change in the calculated area of the graph decreases as the end point. A blood purification device as described in any one of claims 1, 4, and 6, wherein the recirculation detection unit detects recirculated blood and calculates the proportion of recirculated blood in a measurement process separate from the treatment process in which blood purification treatment is performed. The blood purification device of claim 10, further comprising a switching input unit or an instruction input unit that can be operated by an operator, and wherein the measurement process is performed in accordance with input operation of the switching input unit or the instruction input unit. A blood purification device according to any one of claims 1, 4, and 6, wherein the blood characteristic is blood concentration.