Detection Device

Abstract

To provide a detection device that can perform calibration with high accuracy by obtaining a more accurate calibration curve.SOLUTION: A detection device includes: a load sensor 18; a calculation unit 25 that calculates a flow rate or pressure at a detection position of the load sensor 18; a control unit 26 that controls liquid transfer of a liquid flow path so that the flow rate or pressure at the detection position in the liquid flow path is a specific value between an upper limit value and a lower limit value of a control range; and a calibration curve creation unit 27 that acquires a detection value by the load sensor 18 and creates a calibration curve D for calibrating the load sensor 18 and the calculation unit 25 by using at least two values including the detection value while the control unit 26 controls the flow rate or pressure at the detection position in the liquid flow path to be a specific value. The detection device creates the calibration curve D on the basis of the detection values acquired in at least one of a zero-point acquisition process or a span-point acquisition process and a specific point acquisition process.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a detection device for detecting the pressure in a liquid flow path made of a flexible tube through which a predetermined liquid can flow, and to which an over-squeezed tube is connected in part, which is compressed radially and squeezed longitudinally by the squeezing part of a peristaltic pump to cause the liquid inside to flow. [Background technology]

[0002] A typical blood circuit used in hemodialysis treatment is mainly composed of an arterial blood circuit with an arterial puncture needle attached to its tip and a venous blood circuit with a venous puncture needle attached to its tip, and is configured so that a blood purifier such as a dialyzer can be connected to the base ends of the arterial blood circuit and venous blood circuit. A peristaltic blood pump is disposed in the arterial blood circuit, and by driving the blood pump while both the arterial and venous puncture needles are inserted into the patient, blood is collected from the arterial puncture needle and circulated through the arterial blood circuit to the dialyzer. The blood purified by the dialyzer is then circulated through the venous blood circuit and returned to the patient's body via the venous puncture needle, thereby performing dialysis treatment.

[0003] As disclosed in Patent Document 1, a detection device has been proposed that uses a strained tube that is compressed radially and strained longitudinally by the straining part of a blood pump to cause the liquid inside (blood, etc.) to flow, and that can detect the diaphragm pressure of an arterial blood circuit (the pressure between the tip of the arterial blood circuit and the strained tube) by detecting the radial displacement of the strained tube.

[0004] In such detection devices, there is a risk of errors occurring due to individual differences in the ironing tube and the sensor for detecting the radial displacement of the ironing tube, so calibration is performed to suppress such errors. Such calibration is performed by obtaining a calibration curve based on the relationship between the pressure change detected by the fluid pressure measurement unit when the pressure is changed by the blood pump (pressure before and after driving the blood pump) and the detection value (output voltage) of the load sensor (displacement detection sensor). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-83092 Summary of the Invention [Problem to be solved by the invention]

[0006] However, although the above-mentioned conventional detection devices can currently be calibrated without any problems, there has been a growing demand for more accurate calibration.In addition, in recent years, there has been a growing demand for obtaining not only a calibration curve for detecting pressure (vacuum pressure), but also a calibration curve for detecting flow rate ratio (the ratio of the actual flow rate to the set flow rate).

[0007] Therefore, the applicant conducted an experiment to observe the relationship between the flow rate ratio and voltage (output voltage) during calibration, and found that there was a tendency as shown in the graph in Fig. 16. This graph was obtained by plotting the voltage when no liquid is flowing through the liquid flow path (flow rate ratio is 0) as zero voltage (D0) and the voltage when liquid is flowing through the liquid flow path as set (flow rate ratio is 1) as span voltage (Ds), and also by plotting the voltages obtained by changing the flow rate ratio in various ways between these lower and upper limit values.

[0008] According to this graph, it can be seen that the relationship between the flow rate ratio and voltage has inflection points (A1, A2) and a linear region B with a linear tendency between these inflection points (A1, A2). Therefore, if a calibration curve is simply drawn between zero voltage (D0) and span voltage (Ds), the inflection points (A1, A2) will be included, which may result in a large error. It can be seen that this problem occurs not only in the relationship between the flow rate ratio and voltage, but also in the relationship between pressure and voltage.

[0009] The present invention has been made in view of the above circumstances, and has as its object to provide a detection device that can be calibrated with high precision by obtaining a more accurate calibration curve. [Means for solving the problem]

[0010] The invention of claim 1 provides a detection device for detecting a flow rate or pressure of a liquid flow path formed of a flexible tube capable of passing a predetermined liquid, the detection device comprising: a displacement detection unit that detects a radial displacement of the liquid flow path at a predetermined detection position in the liquid flow path; a calculation unit that calculates the flow rate or pressure at the detection position based on a detection value detected by the displacement detection unit; a control unit that controls liquid delivery through the liquid flow path so that the flow rate or pressure at the detection position in the liquid flow path becomes a specific value between an upper limit value and a lower limit value that define a control range; and a calibration curve creating unit that, under control by the control unit so that the flow rate or pressure at the detection position in the displacement detecting unit becomes the specific value, acquires a detection value by the displacement detecting unit and creates a calibration curve for calibrating the displacement detecting unit and the calculating unit by using at least two values ​​including the detection value, and the liquid flow path is made of a peristaltic tube that is compressed in the radial direction and squeezed in the longitudinal direction by a peristaltic pump, causing the liquid inside to flow, and the displacement detecting unit is configured to detect the peristaltic pressure of the peristaltic tube. and a control unit for sequentially performing the following steps: a zero-point acquisition step for continuously rotating the rotor of the peristaltic pump while closing the section upstream of the detection position, thereby acquiring a detection value from the displacement detection unit when the flow rate or pressure at the detection position in the liquid flow path reaches the lower limit; a span-point acquisition step for continuously rotating the rotor of the peristaltic pump while opening the section upstream of the detection position, thereby acquiring a detection value from the displacement detection unit when the flow rate or pressure at the detection position in the liquid flow path reaches the upper limit; and a specific-point acquisition step for rotating the rotor of the peristaltic pump through a predetermined angle while closing the section upstream of the detection position, thereby acquiring a detection value from the displacement detection unit when the flow rate or pressure at the detection position in the liquid flow path reaches the specific value. The detection device creates the calibration curve based on the detection values ​​acquired in at least one of the zero-point acquisition step or the span-point acquisition step and the specific-point acquisition step.

[0011] The invention described in claim 2 is a detection device described in claim 1, which is provided with an alarm unit that issues an alarm when the flow rate or pressure calculated by the calculation unit exceeds a predetermined threshold, and the specific value is set based on the threshold value of the alarm unit.

[0012] The invention described in claim 3 provides a detection device described in claim 1 or claim 2, wherein the at least two values ​​are determined so that an inflection point at which the relationship between the flow rate or pressure of the liquid flow path and the detection value of the displacement detection unit inflects is not included between the at least two values.

[0013] The invention of claim 4 relates to the detection device of claim 1, wherein the peristaltic tube is connected midway through an arterial blood circuit for extracorporeal circulation of a patient's blood during blood purification treatment, and the peristaltic pump is a blood pump that can move blood in the arterial blood circuit, and the displacement detection unit and calculation unit are capable of calculating the flow rate ratio or vent pressure of the liquid flow path from the tip of the arterial blood circuit to the peristaltic tube during the extracorporeal circulation of blood during blood purification treatment.

[0014] The invention described in claim 5 is a blood purification device equipped with the detection device described in any one of claims 1 to 4. [Effects of the Invention]

[0015] According to the invention of claim 1, the flow rate or pressure at the detection position in the liquid flow path is controlled to be a specific value, and a detection value is obtained by the displacement detection unit, and at least two values ​​including the detection value are used to create a calibration curve for calibrating the displacement detection unit and the calculation unit.Therefore, by obtaining a more accurate calibration curve, accurate calibration can be achieved.

[0016] Furthermore, the liquid flow path is configured so that it is compressed radially and squeezed longitudinally by the squeezing part of the squeezing pump, causing the liquid inside to flow, and the displacement detection part detects the radial displacement of the liquid flow path at a detection position upstream of the part of the squeezing tube that is squeezed by the squeezing part, allowing for more accurate calibration.

[0017] Furthermore, a calibration curve is created based on the detection values ​​acquired in at least one of the zero point acquisition process or the span point acquisition process, and the specific point acquisition process, so that after the zero span process, the detection position can be set to a predetermined specific flow rate or pressure by rotating the rotor of the peristaltic pump.

[0018] According to the invention of claim 2, the device is provided with an alarm unit that issues an alarm when the flow rate or pressure calculated by the calculation unit exceeds a preset threshold value, and the specific value is set based on the threshold value of the alarm unit, so that the alarm unit can issue an alarm more accurately, thereby improving the reliability of the device.

[0019] According to the invention of claim 3, at least two values ​​are set so that the inflection point at which the relationship between the flow rate or pressure of the liquid flow path and the detection value of the displacement detection unit inflects is not included between the at least two values, thereby making it possible to suppress errors caused by the inflection point and obtain a more accurate calibration curve.

[0020] According to the invention of claim 4, the displacement detection unit and calculation unit can calculate the flow rate ratio or vent pressure of the liquid flow path from the tip of the arterial blood circuit to the covered hemodialysis tube during the extracorporeal blood circulation process during blood purification treatment, so the flow rate ratio or vent pressure can be calculated with high precision based on an accurate calibration curve.

[0021] According to the invention of claim 5, a blood purification device equipped with the detection device according to any one of claims 1 to 4 can be provided. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a schematic diagram showing a blood purification device to which a detection device according to an embodiment of the present invention is applied; FIG. [Figure 2] FIG. 10 is a perspective view showing a blood pump in which the detection device is installed. [Figure 3] FIG. 10 is a plan view showing a blood pump in which the detection device is installed. [Figure 4] FIG. 10 is a cross-sectional schematic diagram showing a displacement detection unit disposed in the blood pump. [Figure 5] Schematic diagram showing the state during calibration of a blood purification device to which the detection device is applied. [Figure 6] A graph showing the relationship between the flow rate ratio and voltage of the detection device (preliminary experimental results) [Figure 7] Graph showing a calibration curve obtained by the same detection device [Figure 8] Schematic diagram showing the operation of the blood pump during calibration in the detection device [Figure 9] Graph showing the relationship between the flow rate ratio and the voltage of a detection device according to another embodiment of the present invention (preliminary experimental results) [Figure 10] Graph showing a calibration curve obtained by the same detection device [Figure 11] Schematic diagram showing the operation of the blood pump during calibration in the detection device [Figure 12] Graph showing the relationship between suction pressure and voltage of a detection device according to an embodiment of the present invention. [Figure 13] A flowchart illustrating the control process including calibration in a blood purification device applied to the detection device. [Figure 14] FIG. 10 is a perspective view showing a blood pump in which a detection device according to another embodiment of the present invention is provided. [Figure 15] FIG. 10 is a cross-sectional schematic diagram showing a displacement detection unit disposed in the blood pump. [Figure 16] Graph showing the relationship between flow rate ratio and voltage of a conventional detection device DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The detection device according to this embodiment is for detecting the pressure in a blood circuit (specifically, upstream of the location where a blood pump is installed) for extracorporeally circulating a patient's blood for blood purification treatment (e.g., hemodialysis treatment), and the blood circuit to which this device is applied is mainly composed of an arterial blood circuit 1, a venous blood circuit 2, and a dialyzer 3 as a blood purifier, as shown in Fig. 1. The arterial blood circuit 1 corresponds to the "liquid flow path to which a stroke tube 1a is connected in part" of the present invention.

[0024] The arterial blood circuit 1 constitutes a liquid flow path made of a flexible tube through which a predetermined liquid can flow, and an arterial puncture needle (not shown) can be attached to the tip of the tube via a connector a, and an arterial air trap chamber 5 for removing bubbles is connected midway. One end of a dialysate supply line L3 is connected to the arterial blood circuit 1 via a T-shaped tube c, and the other end of the dialysate supply line L3 is connected to a dialysate introduction line L1 via a collection port 19. The dialysate supply line L3 can be opened or closed as desired by a solenoid valve V9, and is configured so that the dialysate from the dialysate introduction line L1 can be supplied into the blood circuit.

[0025] Additionally, an ironed tube 1a is connected midway along the arterial blood circuit 1 (between the T-shaped tube c and the arterial air trap chamber 5), and this ironed tube 1a can be attached to the blood pump 4. The ironed tube 1a is compressed radially and squeezed longitudinally by rollers 10 of the blood pump 4, which will be described in detail later, causing the liquid inside to flow in the direction of rotation of the rotor 9. The ironed tube 1a is made of flexible tubing that is softer and has a larger diameter than the other flexible tubing that makes up the arterial blood circuit 1. A solenoid valve V1 is disposed at the distal end of the arterial blood circuit 1, allowing the flow path to be opened and closed at any time.

[0026] The venous blood circuit 2 constitutes a liquid flow path made of flexible tubing capable of passing a predetermined liquid, and a venous puncture needle (not shown) can be attached to the tip of the venous blood circuit 2 via connector b, and a venous air trap chamber 6 for removing bubbles is connected midway. The flexible tubing constituting the venous blood circuit 2 is made of substantially the same material and dimensions as the flexible tubing constituting the arterial blood circuit 1. An electromagnetic valve V2 is disposed at the tip of the venous blood circuit 2, allowing the flow path to be opened and closed at any time.

[0027] An overflow line L4 extends from the air space side (upper part) of the venous air trap chamber 6, allowing air or gas within the venous air trap chamber 6 to be discharged to the outside, and a solenoid valve V3 is disposed midway along the overflow line L4, allowing the flow path to be opened and closed at any time. Furthermore, a pressure monitor line extends from the air space side (upper part) of the venous air trap chamber 6 to a venous pressure sensor 7. The venous pressure sensor 7 measures the pressure on the air space side of the venous air trap chamber 6, thereby detecting the fluid pressure within the venous blood circuit 2 (venous pressure measured during blood purification treatment).

[0028] A dialyzer 3 is connected between the arterial blood circuit 1 and the venous blood circuit 2. After the arterial and venous puncture needles are inserted into the patient, the blood pump 4 is driven in the normal direction (in the direction of the arrow of the blood pump 4 in Figure 5), so that the patient's blood can be circulated extracorporeally during blood purification treatment through the liquid flow paths formed by the arterial blood circuit 1, venous blood circuit 2, and dialyzer 3.

[0029] On the other hand, before blood purification treatment, as shown in Figure 1, the end of the arterial blood circuit 1 is connected to the end of the venous blood circuit 2 by connecting connector a and connector b, and a closed blood circuit is formed by the arterial blood circuit 1 and the venous blood circuit 2 (including the blood flow path in the dialyzer 3). Then, by supplying dialysate into this closed circuit via the dialysate supply line L3, the blood circuits (arterial blood circuit 1 and venous blood circuit 2) are filled with dialysate, enabling priming. During the priming process, the dialysate is allowed to overflow from the overflow line L4 to clean the closed blood circuit.

[0030] The dialyzer 3 is constructed by housing a plurality of hollow fibers with micropores formed in a housing, and the housing is formed with a blood inlet port 3a, a blood outlet port 3b, a dialysate inlet port 3c, and a dialysate outlet port 3d, of which the blood inlet port 3a is connected to the base end of the arterial blood circuit 1, and the blood outlet port 3b is connected to the base end of the venous blood circuit 2. The dialysate inlet port 3c and the dialysate outlet port 3d are connected to a dialysate inlet line L1 and a dialysate outlet line L2, respectively, which are extended from the dialysis device main body.

[0031] The patient's blood introduced into the dialyzer 3 passes through the internal hollow fiber membrane and is discharged from the blood outlet port 3b, while the dialysate introduced through the dialysate inlet port 3c passes outside the hollow fiber membrane and is discharged from the dialysate outlet port 3d. This allows waste products and the like in the blood passing through the blood flow path to permeate into the dialysate side, thereby purifying the blood, and the purified blood can be returned to the patient's body via the venous blood circuit 2.

[0032] The dialysis device main body has a dialysate inlet line L1 and a dialysate outlet line L2, as well as a duplex pump 21, bypass lines L5 to L8, and solenoid valves V4 to V8. Of these, the duplex pump 21 is disposed across the dialysate inlet line L1 and the dialysate outlet line L2, and introduces dialysate prepared to a predetermined concentration into the dialyzer 3 and discharges the dialysate from the dialyzer 3 after dialysis.

[0033] A solenoid valve V4 is connected in the dialysate inlet line L1 (between the collection port 19 in the dialysate inlet line L1 and the dialyzer 3), and a solenoid valve V5 is connected in the dialysate outlet line L2 (between the dialyzer 3 and the connecting portion of the dialysate outlet line L2 with the bypass line L6). In addition, filtration filters 23 and 24 are connected in the dialysate inlet line L1 between the duplex pump 21 and the solenoid valve V4.

[0034] The filtration filters 23 and 24 are used to filter and purify the dialysate flowing through the dialysate inlet line L1, and bypass lines L5 and L6 for bypassing the dialysate to the dialysate outlet line L2 are connected to the filtration filters 23 and 24. Solenoid valves V6 and V7 are connected to the bypass lines L5 and L6, respectively.

[0035] Meanwhile, a dialysate pressure sensor 20 capable of measuring the fluid pressure of the dialysate is disposed between the connecting portion of the dialysate discharge line L2 with the bypass line L5 and the connecting portion with the bypass line L6. This dialysate pressure sensor 20 is capable of measuring the pressure (fluid pressure) of the dialysate discharged from the dialyzer 3 and flowing through the dialysate discharge line L2 during dialysis treatment (blood purification treatment).

[0036] Furthermore, bypass lines L7 and L8 that bypass the duplex pump 21 are connected to the dialysate discharge line L2, and a water removal pump 22 for removing water from the patient's blood flowing through the blood flow path of the dialyzer 3 is provided in the bypass line L7, and a solenoid valve V8 that can open and close the flow path is provided in the bypass line L8. Although not shown, a pump for adjusting the fluid pressure on the drain side of the duplex pump 21 is provided upstream of the duplex pump 21 in the dialysate discharge line L2 (between the connection with the bypass line L7 and the duplex pump 21).

[0037] 2 to 4, the blood pump 4 according to this embodiment is mainly composed of a stator 8, a rotor 9 that can be rotated within the stator 8, rollers 10 formed on the rotor 9, a pair of upper and lower guide pins 11, an upstream gripping portion 12, a downstream gripping portion 13, and a load sensor 18 as a displacement detection portion. Note that a cover that covers the top of the stator 8 in the blood pump 4 is omitted from the drawings.

[0038] The stator 8 is formed with a mounting recess 8a in which the ironed tube 1a is attached, and is configured so that the ironed tube 1a is attached along the inner peripheral wall surface that forms the mounting recess 8a. A rotor 9 that can be rotated by a motor is disposed approximately in the center of the mounting recess 8a. A pair of rollers 10 and a guide pin 11 are disposed on the side surface of the rotor 9 (the surface facing the inner peripheral wall surface of the mounting recess 8a).

[0039] The roller 10 is rotatable about a rotation axis M formed on the outer edge of the rotor 9, and radially compresses the ironed tube 1a attached to the mounting recess 8a while squeezing it longitudinally (in the direction of blood flow) as the rotor 9 rotates, thereby causing blood to flow within the arterial blood circuit 1. That is, when the ironed tube 1a is attached to the mounting recess 8a and the rotor 9 is driven to rotate, the ironed tube 1a is compressed between the roller 10 and the inner circumferential wall surface of the mounting recess 8a and is squeezed in the rotational direction (longitudinal direction) as the rotor 9 rotates. This squeezing action causes blood in the arterial blood circuit 1 to flow in the rotational direction of the rotor 9, enabling extracorporeal circulation within the blood circuit 1.

[0040] 2, the guide pins 11 consist of a pair of upper and lower pin-shaped members that protrude respectively from the upper and lower ends of the rotor 9 toward the inner peripheral wall surface of the mounting recess 8a, and the ironed tube 1a is held between this pair of upper and lower guide pins 11. That is, when the rotor 9 is driven, the pair of upper and lower guide pins 11 hold the ironed tube 1a in the correct position, and the upper guide pin 11 prevents the ironed tube 1a from coming off upward from the mounting recess 8a.

[0041] The upstream gripping portion 12 is for gripping the upstream side (the portion where the distal end side of the arterial blood circuit 1 is connected) of the ironed tube 1a attached to the mounting recess 8a of the stator 8 in the blood pump 4, and as shown in FIGS. 2 to 4, has a gripping piece 14 that can grip the ironed tube 1a by pressing it radially, and a torsion spring 15 (biasing portion) that biases the gripping piece 14 toward the ironed tube 1a.

[0042] As shown in Fig. 4, the gripping piece 14 is made of a part that can swing around the swing axis La, is biased relatively strongly in the gripping direction by a torsion spring 15, and can be fixed by pressing against the upstream portion of the ironing tube 1a to firmly clamp it. As shown in the figure, the torsion spring 15 is attached to the swing axis La to bias the gripping piece 14, and has a fixed end 15a located at a fixed portion of the stator 8 (in this embodiment, the load sensor 18 attached to the stator 8) and a pressing end 15b that presses against the gripping piece 14. Note that the torsion spring 15 may be replaced with another biasing portion that biases the gripping piece 14.

[0043] The downstream gripping portion 13 is for gripping the downstream side (the portion where the base end side of the arterial blood circuit 1 is connected) of the ironed tube 1a attached to the mounting recess 8a of the stator 8 in the blood pump 4, and has a gripping piece 16 that can grip the ironed tube 1a by pressing it radially, and a torsion spring 17 that urges the gripping piece 16 toward the ironed tube 1a.

[0044] Like the gripping piece 14 of the upstream gripping part 12, the gripping piece 16 is made of a part that can swing around the swing axis Lb, and is urged relatively strongly in the gripping direction by the torsion spring 17, so that it can be fixed by pressing against the downstream portion of the ironing tube 1a and firmly clamping it. Like the torsion spring 15 of the upstream gripping part 12, the torsion spring 17 is attached to the swing axis Lb to urge the gripping piece 16, and has a fixed end located at the fixed part of the stator 8 and a pressing end that presses against the gripping piece 16.

[0045] The load sensor 18 as a displacement detection unit detects radial displacement at a predetermined position (such position will be referred to as the predetermined detection position) upstream of the portion of the ironed tube 1a that is ironed by the rollers 10. Note that the displacement detection unit in this embodiment is configured by the load sensor 18 disposed in the blood pump 4 and detects radial displacement at the predetermined detection position upstream of the portion of the ironed tube 1a that is ironed by the rollers 10, but it may also be configured to detect radial displacement at the predetermined detection position of a flexible tube (e.g., a pillow) that constitutes the arterial blood circuit 1 and is connected upstream of the ironed tube 1a.

[0046] The load sensor 18 according to this embodiment is capable of detecting the radial displacement of the portion of the ironed tube 1a gripped by the upstream gripping part 12, and is configured to detect the load applied to the fixed end 15a of the torsion spring 15 and detect the radial displacement of the ironed tube 1a based on the detected load. This load sensor 18 is capable of generating an electric signal corresponding to the applied load.

[0047] That is, since an arterial puncture needle is attached to the tip of the arterial blood circuit during treatment, when blood is drawn from the patient and circulated through the arterial blood circuit 1 (flowing in the direction of the arrow indicating the drive direction of the blood pump 4 in FIG. 5), negative pressure is generated between the tip of the arterial blood circuit 1 and the blood pump 4. When this negative pressure is generated, the fluid pressure in the warped tube 1a decreases, and the portion of the warped tube 1a gripped by the upstream gripping portion 12 is displaced radially (its diameter decreases), resulting in a decrease in the load detected by the load sensor 18. By detecting this decrease in load, it is possible to detect the generation of negative pressure in the arterial blood circuit 1.

[0048] The load sensor 18 according to this embodiment is electrically connected to the calculation unit 25 via wires or the like. The calculation unit 25 is composed of a microcomputer or the like disposed in the dialysis machine body, for example, and is configured to calculate the pressure and flow rate of the arterial blood circuit 1 based on the radial displacement of the ironing tube 1a detected by the load sensor 18.

[0049] That is, when the load sensor 18 detects the radial displacement of the ironing tube 1a, a predetermined electric signal corresponding to the displacement is sent to the calculation unit 25, and the calculation unit 25 calculates the pressure (venting pressure during blood purification treatment) and flow rate ratio (ratio of actual flow rate to set flow rate) in the arterial blood circuit 1 (in this embodiment, from the tip of the arterial blood circuit 1 to the part where the load sensor 18 is disposed). The flow rate ratio and venting pressure calculated by the calculation unit 25 are configured to be displayed on a monitor (not shown) or the like.

[0050] Furthermore, the calculation unit 25 is electrically connected to the notification unit 28. The notification unit 28 includes a speaker, a monitor, etc., and can issue a notification (such as outputting voice or sound effects from the speaker or displaying a warning on the monitor) when the flow rate or pressure calculated by the load sensor 18 and the calculation unit 25 exceeds a preset value.

[0051] Here, in this embodiment, the system is equipped with a control unit 26 and a calibration curve creation unit 27 for calibrating the load sensor 18 and the calculation unit 25. The control unit 26 sets a predetermined detection position (a position upstream of the portion of the ironed tube 1a that is rubbed by the rollers 10) to a predetermined specific flow rate or pressure, and in this embodiment, as shown in Fig. 5, the detection position is set to a predetermined specific flow rate (flow rate ratio) or pressure by closing the solenoid valves V1 and V9 to close the upstream side of the detection position while rotating the rotor 9 of the blood pump 4 by a predetermined angle.

[0052] That is, the control unit 26 controls the liquid flow path so that the flow rate or pressure at the detection position in the liquid flow path becomes a specific value between the upper and lower limits of the control range. Such specific values ​​include any point between the upper and lower limits of the control range, and may be one or more. Furthermore, the calibration curve creation unit 27 acquires a detection value by the load sensor 18 while the control unit 26 controls the flow rate or pressure at the detection position in the liquid flow path to become a specific value, and creates a calibration curve D for calibrating the load sensor 18 and the calculation unit 25 by using at least two values ​​including the detection value.

[0053] Specifically, during calibration, the control unit 26 closes the solenoid valves V1 and V9 to close the upstream side of the detection position as shown in Figure 5, and rotates the rotor 9, which is at the initial position P0 in the blood pump 4, by a predetermined angle K1 as shown in Figure 8(a), to set the rotor 9 to position P1 as shown in the same figure(b), thereby executing a first step of setting the detection position to a predetermined specific flow rate (specifically, the flow rate ratio F1 shown in Figure 6) or pressure.

[0054] After executing the first step, the control unit 26 maintains the solenoid valves V1 and V9 in a closed state to maintain closure upstream of the detection position, and further rotates the rotor 9 of the blood pump 4 by a predetermined angle K2 to position the rotor 9 at P2 as shown in Fig. 6(c), thereby executing a second step in which the detection position is set to a predetermined specific flow rate (specifically, the flow rate ratio F2 shown in Fig. 6) or pressure. In this way, by intermittently rotating the rotor 9 of the blood pump 4 and passing through the first and second steps, the calibration curve D (see Fig. 7) can be obtained by the calibration curve creation unit 27 based on the detection value D1 at the flow rate ratio F1 and the detection value D2 at the flow rate ratio F2.

[0055] However, according to the results of experiments conducted in advance, the relationship between the flow rate ratio (ratio of actual flow rate to set flow rate) of the liquid flowing at the detection position and the output voltage of the load sensor 18 has a tendency as shown in the graph shown in Fig. 6, with two inflection points (inflection point A1 on the lower limit side and inflection point A2 on the upper limit side) between the lower limit value and the upper limit value. In this embodiment, a calibration curve D (see Fig. 7) is acquired over a range that avoids the inflection points (A1, A2) in a predetermined range between the upper limit value and the lower limit value that can be detected by the load sensor 18 and that has an approximately linear tendency between inflection point A1 on the lower limit side and inflection point A2 on the upper limit side (the range between flow rate ratio F1 and flow rate ratio F2).

[0056] In addition, in a device that calculates a flow rate ratio, the upper limit value detectable by the load sensor 18 refers to the flow rate ratio at the detection position being 1 (the set flow rate and the actual flow rate are equal), and the lower limit value detectable by the load sensor 18 refers to the flow rate ratio at the detection position being 0 (the actual flow rate is 0 relative to the set flow rate). In addition, in a device that calculates pressure (vent pressure), the upper limit value detectable by the load sensor 18 refers to the pressure (hydraulic pressure) when the flow rate ratio at the detection position is 1 (the set flow rate and the actual flow rate are equal), and the lower limit value detectable by the load sensor 18 refers to the pressure (hydraulic pressure) when the flow rate ratio at the detection position is 0 (the actual flow rate is 0 relative to the set flow rate).

[0057] As described above, the control unit 26 according to this embodiment sets a predetermined detection position to a specific flow rate or pressure, but the flow rate or pressure includes not only an absolute value but also a relative value (similar to the relative value of pressure) such as the "flow rate ratio" of this embodiment. Therefore, in addition to the flow rate ratio, other relative values ​​may be obtained by comparison with a reference value other than the set flow rate.

[0058] Furthermore, the range between the flow rate ratios F1 and F2 in this embodiment is a range that does not include the inflection points (A1, A2) and is based on the set value of the notification unit 28, so that notification by the notification unit 28 is performed based on an accurate calibration curve D. For example, when the set value at which notification is performed by the notification unit 28 is the flow rate ratio F, a value obtained by adding a predetermined value to the flow rate ratio F is the flow rate ratio F1, and a value obtained by subtracting a predetermined value from the flow rate ratio F is the flow rate ratio F2, and these are set within a range that does not include the inflection points (A1, A2). Note that, in this embodiment, the flow rate ratios F1 and F2 are set between the inflection points A1 and A2, but the flow rate ratios F1 and F2 may also be set below the inflection point A1 or above the inflection point A2.

[0059] The calibration curve creation unit 27 acquires the detection value of the load sensor 18 when the detection position is set to a specific flow rate or pressure by the control unit 26, and creates and acquires a calibration curve for calibrating the load sensor 18 and the calculation unit 25 based on the relationship between the specific flow rate or pressure and the acquired detection value.In this embodiment, the calibration curve is acquired over a predetermined range between the upper limit value (flow rate ratio 1) and lower limit value (flow rate ratio 0) detectable by the load sensor 18 (the range between the flow rate ratio F1 obtained in the first step executed by the control unit 26 and the flow rate ratio F2 obtained in the second step).

[0060] Specifically, as shown in FIG. 7, the calibration curve creation unit 27 connects the detection value (D1) obtained by the load sensor 18 when a specific flow rate (flow rate ratio F1) or pressure is set in the first step with the detection value (D2) obtained by the load sensor 18 when a specific flow rate (flow rate ratio F2) or pressure is set in the second step at a specific flow rate ratio F1, F2 or pressure set between the flow rate ratio 0 (lower limit value) and the flow rate ratio 1 (upper limit value), and obtains this straight line as the calibration curve D.

[0061] According to this embodiment, the control unit 26 sets the detection position to a predetermined specific flow rate or pressure by rotating the rotor 9 of the blood pump 4 by a predetermined angle while closing the upstream side of the detection position, so that the detection position can be set to a predetermined specific flow rate or pressure by rotating the rotor of the blood pump 4 without the need for a separate pressure detection sensor, etc. In particular, the calibration curve creation unit 27 according to this embodiment obtains the calibration curve D from the detection value D1 by the displacement detection unit when the specific flow rate or pressure is set in the first step and the detection value D2 by the displacement detection unit when the specific flow rate or pressure is set in the second step. Therefore, the detection position can be set to a predetermined specific flow rate or pressure by intermittently rotating the rotor 9 of the blood pump 4 without the need for a separate pressure detection sensor, etc., and an accurate calibration curve D can be obtained.

[0062] Further, examples of the control unit 26 and the calibration curve creating unit 27 according to other embodiments are as follows. During calibration, the control unit 26 performs a zero span process in which the flow rate or pressure at the detection position is set to an upper limit value (flow rate ratio is 1) and a lower limit value (flow rate ratio is 0) by continuously rotating the rotor 9 of the blood pump 4 while closing or opening the upstream side of the detection position by setting the solenoid valves V1 and V9 to a closed state (if the lower limit value is set) or an open state (if the upper limit value is set), and then sets the detection position to a predetermined specific flow rate (flow rate ratio) or pressure by rotating the rotor 9 of the blood pump 4 by a predetermined angle while closing the upstream side of the detection position.

[0063] That is, the control unit 26 sequentially executes the following steps: a zero point acquisition process in which the rotor 9 of the blood pump 4 is continuously rotated while closing the upstream side of the detection position, thereby acquiring the detection value of the load sensor 18 when the flow rate or pressure at the detection position in the liquid flow path reaches its lower limit; a span point acquisition process in which the rotor 9 of the blood pump 4 is continuously rotated while opening the upstream side of the detection position, thereby acquiring the detection value of the load sensor 18 when the flow rate or pressure at the detection position in the liquid flow path reaches its upper limit; and a specific point acquisition process in which the rotor 9 of the blood pump 4 is rotated a predetermined angle while closing the upstream side of the detection position, thereby acquiring the detection value of the load sensor 18 when the flow rate or pressure at the detection position in the liquid flow path reaches a specific value, and creates a calibration curve based on the detection values ​​acquired in the zero point acquisition process, span point acquisition process, and specific point acquisition process.

[0064] For example, in this case, during calibration, the control unit 26 closes the solenoid valves V1 and V9 to close the upstream side of the detection position and opens the solenoid valves V1 and V9 to open the upstream side of the detection position, drives the blood pump 4 to continuously rotate the rotor 9, and performs a zero span process by changing the flow rate ratio at the detection position from 0 to 1. Then, as shown in Fig. 11(a), the control unit 26 rotates the rotor 9, which is at the initial position P0 of the blood pump 4, by a predetermined angle K3 (corresponding to K1+K2 in the previous embodiment), and sets the rotor 9 to position P2 as shown in Fig. 11(b), thereby setting the detection position to a predetermined specific flow rate (specifically, the flow rate ratio F2 shown in Fig. 9) or pressure. Note that in this embodiment, the calibration curve is created using two detection values, one acquired in the span point acquisition process and the other acquired in the specific point acquisition process. However, the calibration curve may be created using two (or three) detection values, one acquired in the zero point acquisition process or the span point acquisition process, and the other acquired in the specific point acquisition process.

[0065] 10, the calibration curve creation unit 27 is configured to acquire the calibration curve D based on the detection value Ds obtained by the load sensor 18 when the flow rate ratio is set to the upper limit value (flow rate ratio is 1) in the zero span step and the detection value D2 obtained by the load sensor 18 when the rotor 9 of the blood pump 4 is rotated by a predetermined angle K3. Specifically, as shown in Fig. 10, the calibration curve creation unit 27 acquires the detection value Ds obtained by the load sensor 18 when the flow rate ratio is 1 (upper limit value), which is the value obtained in the span point acquisition step, and the detection value D2 obtained by the load sensor 18 when the rotor 9 of the blood pump 4 is rotated by the predetermined angle K3 to set the flow rate ratio to F2, multiplies the detection value Ds by a value of a constant ratio to obtain a value Dp, and creates the calibration curve D by connecting the detection value D2 and the value Dp with a straight line.

[0066] According to this other embodiment, the calibration curve creation unit 27 obtains the calibration curve D based on the detection value Ds by the load sensor 18 when the upper limit value is set in the zero span process and the detection value D2 by the load sensor 18 when the rotor 9 of the blood pump 4 is rotated by a predetermined angle.Therefore, after the zero span process, by rotating the rotor 9 of the blood pump 4, the detection position can be set to a predetermined specific flow rate or pressure, and an accurate calibration curve D can be obtained.

[0067] Next, the control content of the dialysis apparatus (blood purification apparatus) according to this embodiment will be described with reference to the flowchart of FIG. Before starting dialysis treatment (blood purification treatment), a fluid substitution step S1 is first performed, in which the piping inside the dialysis device main body is filled with dialysate, and self-diagnosis such as leak diagnosis and testing of the piping is performed. The dialysis preparation step S2 is then performed, in which dialysis conditions are set, the over-stroked tube 1a in the arterial blood circuit 1 is attached to the blood pump 4, and the blood circuit and fluid replacement circuit are primed (filled with substitution fluid). In parallel with the dialysis preparation step S2, priming (gas purging) of the dialysate flow path side of the dialyzer 3 is also performed.

[0068] When the dialysis preparation step S2 is completed, the process proceeds to the calibration step S3. In the calibration step S3, as described above, the control unit 26 acquires the detection value of the load sensor 18 when the detection position is set to a specific flow rate (flow rate ratio) or pressure, and the calibration curve creation unit 27 creates and acquires the calibration curve D for calibrating the load sensor 18 and the calculation unit 25 based on the relationship between the specific flow rate or pressure and the acquired detection value, thereby performing calibration.

[0069] Thereafter, the arterial puncture needle a and the venous puncture needle b are inserted into the patient, and the blood pump 4 is driven to rotate the roller 10 to start blood removal (blood removal start S4), and the patient's blood is circulated extracorporeally via the arterial blood circuit 1 and the venous blood circuit 2. As a result, the blood in the extracorporeal circulation process is purified by the dialyzer 3, and dialysis treatment (blood purification treatment) is performed.

[0070] After blood removal begins, the flow rate ratio or venting pressure is calculated (S5) by the load sensor 18 and calculation unit 25, which have been calibrated in the calibration step (S3), and the calculated flow rate ratio or venting pressure is displayed on a monitor or the like for monitoring. Thereafter, it is determined (S6) whether the flow rate ratio or venting pressure calculated in S5 exceeds a preset value. If the value exceeds the preset value, the process proceeds to S7, where the notification unit 28 issues a predetermined notification. If the value does not exceed the preset value, the process proceeds to S8, where it is determined whether dialysis treatment has ended. If it is determined in S8 that dialysis treatment has not ended, the process returns to S5, and monitoring of the flow rate ratio or venting pressure continues.

[0071] On the other hand, if it is determined in S8 that the dialysis treatment has ended, the process proceeds to S9, where a blood return step S9 (a step of returning the blood in the blood circuit to the patient's body) is followed by a drainage step S10 in which the dialyzer 3 is drained, and the series of controls is completed. By going through the series of steps described above, the flow rate ratio or the blood removal pressure can be detected in real time during dialysis treatment (blood purification treatment), and the flow rate ratio or the blood removal state can be monitored.

[0072] According to this embodiment, a detection value by the load sensor 18 is acquired in a state in which the flow rate or pressure at the detection position in the liquid flow path is controlled to be a specific value, and at least two values ​​including the detected value are used to create a calibration curve D for calibrating the load sensor 18 and the calculation unit 25, so that accurate calibration can be achieved by acquiring a more accurate calibration curve D. Furthermore, since the specific value is set based on the threshold value of the notification unit 28, the notification unit 28 can issue a more accurate notification, thereby improving the reliability of the device.

[0073] Furthermore, the at least two values ​​do not include an inflection point at which the relationship between the flow rate or pressure in the liquid flow path and the detection value of load sensor 18 inflects within the control range, thereby suppressing errors due to inflection points and obtaining a more accurate calibration curve D. Furthermore, load sensor 18 and calculation unit 25 make it possible to calculate the flow rate ratio or venting pressure in the liquid flow path from the tip of arterial blood circuit 1 to covered stroke tube 1a during the extracorporeal blood circulation process during blood purification treatment, so the flow rate ratio or venting pressure can be calculated with high precision based on the accurate calibration curve D.

[0074] The blood pump 4 is equipped with gripping portions (upstream gripping portion 12 and downstream gripping portion 13) for gripping the ironing tube 1a attached to the blood pump 4, and the load sensor 18 serving as a displacement detection portion is capable of detecting radial displacement of the portion gripped by the upstream gripping portion 12. Therefore, by attaching the ironing tube 1a to the blood pump 4 and gripping it with the upstream gripping portion 12, the ironing tube 1a is attached to the detection device, thereby reducing the workload of medical personnel and the like.

[0075] Furthermore, the upstream gripping portion 12 has a gripping piece 14 that can grip the ironed tube 1a by pressing it radially, and a torsion spring 15 (biasing portion) that biases the gripping piece 14 toward the ironed tube 1a. The load sensor 18, which serves as a displacement detection portion, detects the load applied to the fixed end 15a of the torsion spring 15 and detects the radial displacement of the ironed tube 1a based on the detected load. Therefore, the torsion spring 15 in the blood pump 4 can have both the function of generating a gripping force on the ironed tube 1a and the function of detecting the pressure in the arterial blood circuit 1.

[0076] Although the present embodiment has been described above, the present invention is not limited to this. For example, the calculation unit 25 may calculate the suction pressure at the detection position, and as shown in FIG. 12, the calibration curve creation unit 27 may obtain a calibration curve D over a predetermined range avoiding the inflection point A3 based on a previously obtained graph showing the relationship between the suction pressure generated by the control unit 26 and the voltage (output voltage) obtained by the load sensor 18.

[0077] Furthermore, in addition to the calibration curve D being created using two specific values, the calibration curve D may be created using two values, one specific value and a zero value (or a span value). Note that the calibration curve D may be created using three or more detection values.

[0078] 14 and 15 may be used instead of the blood pump 4. As shown in the figures, the blood pump 4' is mainly composed of a stator 8, a rotor 9 that can be rotated within the stator 8, rollers 10 formed on the rotor 9, a pair of upper and lower guide pins 11, an upstream gripping portion 12', a downstream gripping portion 13, and a pressure transducer 30 as a displacement detection portion. Note that components in the blood pump 4' that are the same as those in the previous embodiment are designated by the same reference numerals, and their description will be omitted.

[0079] The upstream gripping portion 12′ is for gripping the upstream side (the portion where the distal end side of the arterial blood circuit 1 is connected) of the ironed tube 1a attached to the mounting recess 8a of the stator 8 in the blood pump 4′, and as shown in FIG. 15, has a gripping piece 14 that can grip the ironed tube 1a by pressing it radially, and a torsion spring 15 (biasing portion) that biases the gripping piece 14 toward the ironed tube 1a.

[0080] The pressure transducer 30 as a displacement detection section is capable of detecting radial displacement of the portion of the ironed tube 1a gripped by the upstream gripping section 12′. In this embodiment, the pressure transducer 30 is disposed opposite the gripping piece 14 across the ironed tube 1a, detects the pressure applied to the side of the ironed tube 1a pressed by the gripping piece 14, and detects the radial displacement of the ironed tube 1a based on the detected pressure.

[0081] That is, when blood is drawn from a patient and circulated through the arterial blood circuit 1, if negative pressure is generated between the tip of the arterial blood circuit 1 and the blood pump 4', the fluid pressure in the warped tube 1a decreases, and the portion of the warped tube 1a gripped by the upstream gripping portion 12' tends to displace radially (it tends to flatten and reduce the diameter on the minor axis side), resulting in a decrease in the pressure detected by the pressure transducer 30. By detecting this decrease in pressure, it is possible to detect the generation of negative pressure in the arterial blood circuit 1.

[0082] As in the previous embodiment, the pressure transducer 30 according to this embodiment is electrically connected to the calculation unit 25 via wires or the like. The calculation unit 25 is composed of a microcomputer or the like disposed in the dialysis machine body, for example, and is configured to calculate the pressure and flow rate ratio of the arterial blood circuit 1 (liquid flow path) based on the radial displacement of the ironed tube 1a detected by the pressure transducer 30.

[0083] The pressure transducer 30 and the calculation unit 25 can be calibrated using the calibration curve D obtained by the calibration curve creation unit 27. The load sensor 18 and pressure transducer 30 attached to the blood pumps 4, 4' may be replaced by other types of displacement detection units, or may be attached to a location separate from the blood pumps 4, 4'. Furthermore, the present invention can be applied to other types of blood circuits (including those in which the dialyzer 3 is replaced by other types of blood purifiers) and dialysis apparatus main bodies (including those using a chamber system instead of the duplex pump 21). The peristaltic pump used may be, in addition to a blood pump, for example, a replacement fluid pump. [Industrial Applicability]

[0084] 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. [Explanation of symbols]

[0085] 1 Arterial blood circuit (liquid flow path) 1a Covering tube 2 Venous blood circuit 3 Dialyzer (blood purifier) 4.4' Blood pump (peristaltic pump) 5. Arterial Air Trap Chamber 6. Venous Air Trap Chamber 7 Venous pressure sensor 8 Stator 9 rotor 10 Roller (squeezing part) 11 Guide pin 12, 12' Upstream grip section 13 Downstream grip part 14 Grip piece 15 Torsion spring 16 Grip piece 17 Torsion Spring 18 Load sensor (displacement detection part) 19 Collection port 20 Dialysis fluid pressure sensor 21 Duplex Pump 22 Water removal pump 23 Filtration filter 24 Filtration filter 25 Calculation section 26 Control Unit 27 Calibration curve creation section 28 Information Department 30 Pressure transducer (displacement detection part) V1~V9 solenoid valves D. Calibration curve

Claims

1. A detection device for detecting a flow rate or pressure of a liquid flow path made of a flexible tube through which a predetermined liquid can flow, a displacement detection unit that detects a radial displacement of the liquid flow path at a predetermined detection position in the liquid flow path; a calculation unit that calculates a flow rate or a pressure at the detection position based on the detection value detected by the displacement detection unit; a control unit that controls the liquid flow through the liquid flow path so that the flow rate or pressure at the detection position in the liquid flow path becomes a specific value between an upper limit value and a lower limit value that define a control range; a calibration curve creation unit that acquires a detection value by the displacement detection unit and creates a calibration curve for calibrating the displacement detection unit and the calculation unit by using at least two values ​​including the detection value, while the control unit controls the flow rate or pressure at the detection position in the liquid flow path to be the specific value; and the liquid flow path is made of a squeezed tube that is compressed in the radial direction and squeezed in the longitudinal direction by a squeezing part of a peristaltic pump, causing the liquid inside to flow; the displacement detection part detects the radial displacement of the liquid flow path at the detection position that is upstream of a part of the squeezed tube that is squeezed by the squeezing part; and The control unit a zero-point acquisition step of continuously rotating the rotor of the peristaltic pump while closing the upstream side of the detection position, thereby acquiring the detection value of the displacement detection unit when the flow rate or pressure at the detection position in the liquid flow path reaches the lower limit value; a span point acquisition step of acquiring a detection value of the displacement detection unit when the flow rate or pressure at the detection position in the liquid flow path reaches the upper limit value by continuously rotating the rotor of the peristaltic pump with the upstream side of the detection position open; a specific point acquisition step of acquiring a detection value of the displacement detection unit when the flow rate or pressure at the detection position in the liquid flow path reaches the specific value by rotating the rotor of the peristaltic pump through a predetermined angle while closing the upstream side of the detection position, The detection device creates the calibration curve based on the detection values ​​acquired in at least one of the zero point acquisition step and the span point acquisition step, and the specific point acquisition step.

2. 2. The detection device according to claim 1, further comprising an alarm unit that issues an alarm when the flow rate or pressure calculated by the calculation unit exceeds a predetermined threshold value, and the specific value is set based on the threshold value of the alarm unit.

3. 3. A detection device according to claim 1, wherein the at least two values ​​are determined so that an inflection point at which the relationship between the flow rate or pressure of the liquid flow path and the detection value of the displacement detection unit inflects is not included between the at least two values.

4. 2. The detection device according to claim 1, wherein the peristaltic tube is connected midway through an arterial blood circuit for extracorporeally circulating the patient's blood during blood purification treatment, and the peristaltic pump is a blood pump that can move the blood in the arterial blood circuit, and the displacement detection unit and calculation unit are capable of calculating the flow rate ratio or the vent pressure of the liquid flow path from the tip of the arterial blood circuit to the peristaltic tube during the extracorporeal circulation of blood during blood purification treatment.

5. A blood purification device comprising the detection device according to any one of claims 1 to 4.

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