JP7592516B2 - Blood Purification Device - Google Patents

Description

The present invention relates to a blood purification device for purifying a patient's blood and performing blood purification therapy.

A typical blood circuit used during 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 each of the base ends of the arterial blood circuit and venous blood circuit. A peristaltic blood pump is provided 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 in the arterial blood circuit to the dialyzer, and the blood purified by the dialyzer is circulated in the venous blood circuit and returned to the patient's body via the venous puncture needle for dialysis treatment.

As disclosed in Patent Document 1, a blood purification device has been proposed that uses a squeezed tube that is compressed radially and squeezed longitudinally by the squeezing part of a blood pump to move the liquid inside (blood, etc.), and is equipped with a detection unit that can detect the diaphragm pressure of the arterial blood circuit (the pressure between the tip of the arterial blood circuit and the squeezed tube) by detecting the radial displacement of the squeezed tube.

JP 2014-83092 A

However, in the above-mentioned conventional detection unit, because the detection unit detects the radial displacement of the over-stroking tube made of a flexible tube, there was a possibility that the reaction force (repulsive force caused by elasticity) of the flexible tube at the detection position would decrease over the course of blood purification treatment, resulting in a false detection. However, because it was difficult to visually determine accurately whether the detection value of the detection unit was appropriate or an erroneous detection due to a decrease in the reaction force of the flexible tube, it was difficult to smoothly respond when the detection value of the detection unit changed.

The present invention was made in consideration of these circumstances, and aims to provide a blood purification device that can smoothly respond when the detection value of the detection unit changes.

A blood purification device according to one embodiment of the present invention is a blood purification device that circulates a patient's blood extracorporeally through a blood purifier and a blood circuit to purify the blood, and includes a blood pump for pumping blood through the blood circuit, a piping section having a dialysate inlet line for introducing dialysate into the blood purifier and a effluent discharge line for discharging effluent from the blood purifier, a first detection section disposed at a predetermined detection position in the blood circuit and detecting a flow rate or pressure of liquid, a second detection section for detecting the flow rate or pressure of either the liquid downstream of the detection position in the blood circuit or the dialysate in the piping section, and a judgment section for judging the appropriateness of the detection value of the first detection section based on a change in the flow rate or pressure detected by the second detection section when the detection value of the first detection section reaches a predetermined threshold value , and for correcting the detection value of the first detection section when the judgment section judges that the detection value of the first detection section is inappropriate .

According to the present invention, when the detection value of the first detection unit changes beyond a predetermined threshold, it is compared with the pressure change detected by the second detection unit to determine whether the detection value of the first detection unit is appropriate, allowing for smooth response when the detection value of the first detection unit changes.

FIG. 1 is a schematic diagram showing a blood purification device according to an embodiment of the present invention; FIG. 2 is a perspective view showing a blood pump in which a detection unit (first detection unit) of the blood purification apparatus is disposed. FIG. FIG. 2 is a schematic cross-sectional view showing a first detection unit provided in the blood pump. FIG. 2 is a schematic diagram showing the state during initial calibration of the blood purification device; Graph showing the relationship between flow rate ratio and voltage of the detection device (preliminary experimental results) Graph showing a calibration curve obtained by initial calibration in the detection device. FIG. 13 is a schematic diagram showing the operation of a blood pump during initial calibration in the detection device. FIG. 2 is a schematic diagram showing the state during blood purification treatment in the blood purification device. 13 is a graph showing the transition of the set blood flow rate and the estimated blood flow rate (detection value of the first detection unit) when poor blood removal occurs in the blood purification device. 13 is a graph showing a case where the detection value of the second detection unit also decreases when the detection value of the first detection unit decreases in the blood purification apparatus. 13 is a graph showing a case where the detection value of the first detection unit decreased but the detection value of the second detection unit did not decrease in the blood purification apparatus. Graph showing a calibration curve obtained by initial calibration and a corrected calibration curve in the blood purification device. Graph showing the difference between correcting the calibration curve and not correcting it in the blood purification device A flowchart for explaining the control contents of the blood purification device. Graphs showing venous pressure, dialysis fluid pressure, and estimated blood flow rate detected in the blood purification device (when the judgment unit judges that they are inappropriate) Graphs showing venous pressure, dialysis fluid pressure, and estimated blood flow rate detected in the blood purification device (when the judgment unit judges them to be appropriate) FIG. 11 is a perspective view showing a blood pump applied to a blood purification device according to another embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing a first detection unit provided in the blood pump.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
The blood purification device of this embodiment is intended to purify a patient's blood for blood purification treatment (e.g., hemodialysis treatment) by extracorporeally circulating the blood through a blood purifier and a blood circuit, and is configured with a blood circuit having an arterial blood circuit 1 and a venous blood circuit 2, and a dialyzer 3 as a blood purifier.

The arterial blood circuit 1 constitutes a liquid flow path made of a flexible tube capable of passing a specified liquid, 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 the dialysis fluid supply line L3 is connected to the arterial blood circuit 1 via a T-shaped tube c, and the other end of the dialysis fluid supply line L3 is connected to the dialysis fluid introduction line L1 via a collection port 19. The dialysis fluid supply line L3 can be opened and closed as desired by a solenoid valve V9, and is configured so that the dialysis fluid from the dialysis fluid introduction line L1 can be supplied into the blood circuit.

In addition, a squeezed tube 1a is connected to the middle of the arterial blood circuit 1 (between the T-shaped tube c and the arterial air trap chamber 5), and this squeezed tube 1a can be attached to the blood pump 4. The squeezed tube 1a is compressed radially and squeezed longitudinally by the rollers 10 of the blood pump 4, which will be described in detail later, to cause the liquid inside to flow in the direction of rotation of the rotor 9. It is made of a flexible tube that is softer and has a larger diameter than the other flexible tubes that make up the arterial blood circuit 1. In addition, a solenoid valve V1 is provided at the tip side of the arterial blood circuit 1, so that the flow path can be opened and closed at any time.

Furthermore, a pressure monitor line is provided on the air layer side (upper part) of the arterial air trap chamber 5, which extends to the inlet pressure sensor 8. The inlet pressure sensor 8 is capable of detecting the inlet pressure of the dialyzer 3 in the arterial blood circuit 1 by measuring the pressure on the air layer side of the arterial air trap chamber 5.

The venous blood circuit 2 constitutes a liquid flow path made of flexible tubing capable of passing a specified 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 tube constituting the venous blood circuit 2 is made of substantially the same material and dimensions as the flexible tube constituting the arterial blood circuit 1. An electromagnetic valve V2 is provided at the tip of the venous blood circuit 2, allowing the flow path to be opened and closed at any time.

On the air layer side (upper part) of the venous air trap chamber 6, an overflow line L4 is provided that can discharge the air or gas in the venous air trap chamber 6 to the outside, and an electromagnetic valve V3 that can open and close the flow path at any time is provided midway along the overflow line L4. Furthermore, on the air layer side (upper part) of the venous air trap chamber 6, a pressure monitor line is provided that extends to the venous pressure sensor 7. The venous pressure sensor 7 is capable of detecting the fluid pressure in the venous blood circuit 2 (venous pressure measured during blood purification treatment) by measuring the pressure on the air layer side of the venous air trap chamber 6.

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 9), 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, the venous blood circuit 2, and the dialyzer 3.

On the other hand, before blood purification treatment, as shown in FIG. 1, the end of the arterial blood circuit 1 and the end of the venous blood circuit 2 are connected by connecting the connector a and the connector b, and a closed circuit on the blood circuit side can be 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 dialysis fluid into this closed circuit via the dialysis fluid supply line L3, the blood circuit (arterial blood circuit 1 and venous blood circuit 2) can be filled with dialysis fluid, making it possible to perform the priming operation. During the priming operation, the dialysis fluid can be overflowed from the overflow line L4 to clean the closed circuit on the blood circuit side.

The dialyzer 3 is composed of a housing containing multiple hollow fibers with micropores formed therein, 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. 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 effluent discharge line L2, respectively, which are extended from the dialysis device body.

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 from the dialysate inlet port 3c passes outside the hollow fiber membrane and is discharged from the dialysate outlet port 3d. This allows waste products in the blood passing through the blood flow path to be permeated to the dialysate side and purified, and the purified blood can be returned to the patient's body via the venous blood circuit 2.

The dialysis device body is equipped with a piping section having a dialysis fluid inlet line L1 and a waste fluid discharge line L2, as well as a duplex pump 21, bypass lines L5-L8 (which are also included as piping sections of the present invention), and solenoid valves V4-V8. Of these, the duplex pump 21 is disposed across the dialysis fluid inlet line L1 and the waste fluid discharge line L2, and introduces dialysis fluid prepared to a predetermined concentration into the dialyzer 3 and discharges the waste fluid after dialysis from the dialyzer 3.

A solenoid valve V4 is connected to the dialysis fluid inlet line L1 (between the collection port 19 in the dialysis fluid inlet line L1 and the dialyzer 3), and a solenoid valve V5 is connected to the effluent discharge line L2 (between the connection point of the effluent discharge line L2 with the bypass line L6 and the dialyzer 3). Filters 23 and 24 are connected between the duplex pump 21 and the solenoid valve V4 in the dialysis fluid inlet line L1.

The filtration filters 23, 24 are used to filter and purify the dialysis fluid flowing through the dialysis fluid inlet line L1, and bypass lines L5, L6 are connected to the filtration filters 23, 24, respectively, to guide the dialysis fluid to the drainage discharge line L2. Solenoid valves V6, V7 are connected to the bypass lines L5, L6, respectively.

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

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

The blood pump 4 according to this embodiment is a peristaltic pump, and as shown in Figures 2 to 4, is mainly composed of a stator G, a rotor 9 that can be rotated within the stator G, a roller 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 first detection portion. Note that the cover that covers the top of the stator G in the blood pump 4 has been omitted from the figures.

The stator G is formed with a mounting recess Ga in which the ironed tube 1a (ironed portion) is attached, and is configured so that the ironed tube 1a is attached along the inner peripheral wall surface that forms the mounting recess Ga. A rotor 9 that can be rotated by a motor is disposed approximately in the center of the mounting recess Ga. 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 Ga).

The roller 10 is rotatable around a rotation axis M formed on the outer edge of the rotor 9, and compresses the ironed tube 1a attached to the mounting recess Ga in the radial direction while squeezing it in the longitudinal direction (the direction of blood flow) as the rotor 9 rotates, thereby allowing blood to flow and be pumped within the arterial blood circuit 1. That is, when the ironed tube 1a is attached to the mounting recess Ga and the rotor 9 is rotated, the ironed tube 1a is compressed between the roller 10 and the inner wall surface of the mounting recess Ga, and is squeezed in the rotational direction (longitudinal direction) as the rotor 9 rotates. This squeezing action causes the blood in the arterial blood circuit 1 to flow in the rotational direction of the rotor 9, making it possible to circulate the blood extracorporeally within the blood circuit 1.

As shown in FIG. 2, the guide pins 11 are a pair of upper and lower pin-shaped members that protrude from the upper and lower ends of the rotor 9 toward the inner circumferential wall surface of the mounting recess Ga, and the ironed tube 1a is held between these upper and lower guide pins 11. In other words, when the rotor 9 is driven, the 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 escaping upward from the mounting recess Ga.

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

As shown in FIG. 4, the gripping piece 14 is made of a part that can swing around the swing axis La, and is biased relatively strongly in the gripping direction by the torsion spring 15, and can be fixed by pressing against the upstream part 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 the fixed part of the stator G (in this embodiment, the load sensor 18 attached to the stator G) and a pressing end 15b that presses the gripping piece 14. Note that the torsion spring 15 may be replaced by another biasing part that biases the gripping piece 14.

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 Ga 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 biases the gripping piece 16 toward the ironed tube 1a.

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 biased relatively strongly in the gripping direction by the torsion spring 17, and can be fixed by pressing against the downstream part of the ironing tube 1a to firmly clamp it. Like the torsion spring 15 of the upstream gripping part 12, the torsion spring 17 is attached to the swing axis Lb to bias the gripping piece 16, and has a fixed end located at the fixed part of the stator G and a pressing end that presses against the gripping piece 16.

The blood pump 4 according to this embodiment is equipped with a load sensor 18 constituting a first detection unit. The load sensor 18 detects a load that changes according to the radial displacement at a predetermined position (referred to as the predetermined detection position) upstream of the part of the ironed tube 1a that is ironed by the roller 10. The first detection unit in this embodiment is configured with the load sensor 18 disposed in the blood pump 4 and detects the radial displacement at the predetermined detection position upstream of the part of the ironed tube 1a that is ironed by the roller 10, but may also detect the radial displacement at the predetermined detection position of a flexible tube that constitutes the arterial blood circuit 1 connected upstream of the ironed tube 1a (e.g., a pillow, etc.).

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 portion 12, and 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. This load sensor 18 is capable of generating an electrical signal according to the applied load.

That is, since an arterial puncture needle is attached to the tip of the arterial blood circuit during dialysis treatment, when blood is taken from the patient and made to flow through the arterial blood circuit 1 (flowing in the direction of the arrow indicating the drive direction of the blood pump 4 in FIG. 9), negative pressure is generated between the tip of the arterial blood circuit 1 and the blood pump 4. When such negative pressure is generated, the liquid pressure in the ironed tube 1a decreases, and the part of the ironed tube 1a gripped by the upstream gripping portion 12 is displaced radially (the diameter becomes smaller), so that the load detected by the load sensor 18 decreases. By detecting this decrease in load, it is possible to detect the generation of negative pressure in the arterial blood circuit 1. In this way, at a detection position upstream of the part squeezed by the roller 10 (squeezing part) in the blood circuit's fluid transfer direction (direction from the tip of the arterial blood circuit 1 to the tip of the venous blood circuit 2), the load sensor 18 detects the load applied by the gripping piece 14, which swings in response to the radial displacement of the squeezed tube 1a (squeezing part).

The load sensor 18 according to this embodiment is electrically connected to the calculation unit 25 through an extended wiring. The calculation unit 25 constitutes the first detection unit of the present invention together with the load sensor 18, 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.

That is, when the load sensor 18 detects an output voltage corresponding to the radial displacement of the ironing tube 1a, the output signal is sent to the calculation unit 25, which calculates the pressure (the withdrawal pressure during blood purification treatment) and the flow rate ratio (the ratio of the actual flow rate to the set flow rate) at the detection position of the arterial blood circuit 1 (in this embodiment, between the tip of the arterial blood circuit 1 and the part where the load sensor 18 is arranged). The flow rate ratio and withdrawal pressure calculated by the calculation unit 25 are configured to be displayed on a monitor (not shown) as the estimated blood flow rate and estimated blood withdrawal amount.

In addition, in this embodiment, the device 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 specific flow rate or pressure at a predetermined detection position (a position upstream of the part of the ironed tube 1a that is ironed by the roller 10). 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 rotating the rotor 9 of the blood pump 4 by a predetermined angle while closing the upstream side of the detection position by closing the solenoid valves V1 and V9. The calculation unit 25, the control unit 26, and the calibration curve creation unit 27 are, for example, composed of a microcomputer or the like arranged in the dialysis device body.

That is, the control unit 26 controls the liquid supply so that the flow rate or pressure at the detection position in the blood circuit becomes a specific value within the control range. Such a specific value includes any point between the upper and lower limits of the control range, and may be not limited to one but may be two or more. In addition, 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.

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 FIG. 5, and rotates the rotor 9, which is in the initial position P0 in the blood pump 4, by a predetermined angle K1 as shown in FIG. 8(a) to set the rotor 9 to position P1 as shown in FIG. 8(b), thereby executing the first step of setting the detection position to a predetermined specific flow rate (specifically, the flow rate ratio F1 shown in FIG. 6) or pressure.

After executing the first step, the control unit 26 holds the solenoid valves V1 and V9 in a closed state to maintain the closure upstream of the detection position, and further rotates the rotor 9 of the blood pump 4 by a predetermined angle K2 to set the rotor 9 to position P2 as shown in FIG. 6(c), thereby executing the second step of setting the detection position 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 going through the first and second steps, the calibration curve creation unit 27 can obtain the calibration curve D (see FIG. 7) based on the detection value D1 at the flow rate ratio F1 and the detection value D2 at the flow rate ratio F2.

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 in FIG. 6, and has two inflection points (lower limit inflection point A1 and upper limit inflection point A2) between the lower limit value and the upper limit value. In this embodiment, the calibration curve D (see FIG. 7) is obtained 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 (a range that does not cross the inflection points), and has a substantially linear tendency between the lower limit inflection point A1 and the upper limit inflection point A2 (a range between flow rate ratio F1 and flow rate ratio F2).

When the calculation unit 25 calculates the flow ratio, the upper limit value detectable by the load sensor 18 refers to the flow 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 ratio at the detection position being 0 (the actual flow rate is 0 relative to the set flow rate). When the calculation unit 25 calculates the pressure (ventilation pressure), the upper limit value detectable by the load sensor 18 refers to the pressure (hydraulic pressure) when the flow 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 ratio at the detection position is 0 (the actual flow rate is 0 relative to the set flow rate). Note that the upper limit value is not limited to 1 and the lower limit value is 0, and may be, for example, an upper limit value of 1 or more (the actual flow rate exceeds the set flow rate).

The calibration curve creation unit 27 acquires the detection value by 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 (flow rate ratio 1) and lower limit (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).

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 flow rate ratio 0 (lower limit value) and flow rate ratio 1 (upper limit value) with a straight line, and obtains the straight line as the calibration curve D.

Here, in this embodiment, when the detection value (estimated blood flow rate or estimated dialysis pressure) of the first detection unit (load sensor 18 and calculation unit 25) reaches a predetermined threshold, a judgment unit 28 is provided to judge whether the detection value of the first detection unit is appropriate based on the change in flow rate or pressure detected by the second detection unit. The judgment unit 28, like the control unit 26 and the calibration curve acquisition unit 27, is composed of a microcomputer or the like arranged in the dialysis device body. The second detection unit is composed of one or a combination of two or more of the inlet pressure sensor 8 arranged in the arterial blood circuit 1 to detect the inlet pressure of the dialyzer 3, the venous pressure sensor 7 arranged in the venous blood circuit 2 to detect the venous pressure, and the dialysis fluid pressure sensor 20 to detect the fluid pressure of the dialysis fluid (drainage) in the drainage discharge line L2.

The detection value of the first detection unit and the detection value of the second detection unit have a certain correlation or causal relationship. For example, when the second detection unit is configured to be arranged downstream of the blood pump 4, such as the venous pressure sensor 7 and the inlet pressure sensor 8, the flow rate or pressure downstream of the blood pump 4 changes as the flow rate or pressure of the blood pump 4 changes. Also, when the second detection unit is configured to be arranged in a piping section connected to the blood circuit via the dialyzer 3 or the dialysis fluid supply line L3, such as the dialysis fluid pressure sensor 20, the flow rate or pressure may change depending on the flow rate or pressure of the blood pump 4, although the degree of influence is different compared to the venous pressure sensor 7 and the inlet pressure sensor 8. In this way, focusing on the correlation or causal relationship between the detection values of the first detection unit and the second detection unit, the judgment unit 28 judges whether the detection value of the first detection unit is appropriate based on the change in the flow rate or pressure detected by the second detection unit when the detection value of the first detection unit reaches a predetermined threshold value.

Specifically, when the pressure detected by the second detection unit changes as the detection value of the first detection unit reaches a predetermined threshold, the judgment unit 28 judges that the detection value of the first detection unit is appropriate, and when the pressure detected by the second detection unit does not change as the detection value of the first detection unit reaches a predetermined threshold, the judgment unit 28 judges that the detection value of the first detection unit is inappropriate.

For example, as shown in FIG. 10, when the estimated blood flow rate Q2 calculated by the calculation unit 25 based on the output voltage of the load sensor 18 is reduced by 20% from the set blood flow rate Q1, the judgment unit 28 takes into consideration the venous pressure detected by the venous pressure sensor 7 as the second detection unit, and as shown in FIG. 11, when the venous pressure W1 has decreased from the reference value W0, judges that the detection value of the first detection unit is appropriate, and when the venous pressure W1 has not decreased from the reference value W0 (is maintained at a value greater than the reference value W0), as shown in FIG. 12, judges that the detection value of the first detection unit is inappropriate.

The reference value W0 is a value obtained by adding or subtracting a predetermined value to the venous pressure after the blood pump 4 starts to operate or the flow rate is changed and the venous pressure stabilizes (e.g., one minute later). The above-mentioned judgment by the judgment unit 28 can be set under the conditions that (1) the estimated blood flow rate by the first detection unit 18 can be used during the blood purification treatment process, and (2) a set time (e.g., about 5 minutes) has elapsed since the start of blood purification treatment. The reference value W0 does not have to be a value subtracted from the venous pressure after the flow rate is changed and the venous pressure stabilizes. For example, a venous pressure detected in the past may be used as a reference value, and the appropriateness of the detection value of the first detection unit may be determined by comparing it with this. The venous pressure detected in the past is preferably a venous pressure detected in the past within the range of the blood purification treatment being performed, and does not include the venous pressure detected in the blood purification treatment before the previous time. More preferably, the venous pressure detected relatively recently (several minutes to several tens of minutes ago) within the range of the blood purification treatment being performed is preferable.

In addition, in this embodiment, a notification unit 29 is provided that issues an alarm based on the detection value of the first detection unit when the determination unit 28 determines that the detection value of the first detection unit is appropriate, and issues a notification that the detection value of the first detection unit is inappropriate or suggests that the detection value of the first detection unit is inappropriate when the determination unit 28 determines that the detection value of the first detection unit is inappropriate. The notification unit 29 includes a speaker, a monitor, etc., and is configured to output voice, sound effects, etc. from the speaker, display a warning on the monitor, etc.

Furthermore, in this embodiment, as described above, before blood is circulated extracorporeally in the blood circuit to perform blood purification treatment, the first detection unit is initially calibrated to obtain a calibration curve D, and if the judgment unit 28 judges that the detection value of the first detection unit is inappropriate, the calibration curve D obtained by the initial calibration is corrected to obtain a corrected calibration curve E.

Specifically, when the judgment unit 28 judges that the detection value of the first detection unit is inappropriate, the driving speed of the blood pump 4 is reduced to, for example, 40 (approximately mL/m) or the driving of the blood pump 4 is stopped, and the output voltage detected by the load sensor 18 at that time is set as the span voltage (Ds1). Then, as shown in FIG. 13, based on a predetermined calculation formula using the span voltage (Ds0) and span voltage (Ds1) obtained in the initial calibration as parameters, the correction value E1 of D1 at the flow ratio F1 and the correction value E2 of D2 at the flow ratio F2 are calculated, and the calibration curve E is obtained by correcting the calibration curve D based on these correction values E1 and E2.

For example, the predetermined arithmetic formula may be one that calculates the detection value (D1, D2) at the time of initial calibration based on the difference or ratio between the span voltage (Ds0) obtained at the time of initial calibration and the span voltage (Ds1) obtained at the time of correction to obtain the correction value (E1, E2), or may have a value obtained by a previously conducted experiment as a parameter. Also, the arithmetic formula or its parameters for correcting the calibration curve D may be changed according to the material or diameter dimension of the blood circuit used. Thus, according to this embodiment, the calibration curve D can be corrected based on the detection value of the load sensor 18 when the driving amount of the blood pump 4 is reduced or stopped, and an appropriate calibration curve E can be obtained.

However, as shown in FIG. 14, when the judgment unit 28 judges that the detection value of the first detection unit is inappropriate and the calibration curve D at the time of initial calibration is used, a flow rate (Na) lower than the blood pump set flow rate is detected even if the blood pump flow rate is moving at the set blood pump flow rate. On the other hand, when the judgment unit 28 judges that the detection value of the first detection unit is inappropriate and the calibration curve E after correction is used, a flow rate (Nb) approximately equal to the set blood pump flow rate can be detected as long as the blood pump flow rate is moving at the set blood pump flow rate. Note that the symbol Nc in the figure indicates the detection value of the load sensor 18.

Next, the control contents of the 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 liquid replacement step S1 is first performed to fill the inside of the piping in the dialysis device main body with dialysis fluid, and to perform self-diagnosis such as leak diagnosis and testing of the piping. Then, the system proceeds to a dialysis preparation step S2, in which dialysis conditions are set, the covered tube 1a in the arterial blood circuit 1 is attached to the blood pump 4, and the blood circuit and replacement fluid circuit are primed (filled with replacement 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.

When the dialysis preparation step S2 is completed, the process proceeds to the calibration step S3. In the calibration step S3, the state shown in FIG. 5 is established, and 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 a calibration curve D for calibrating (initial calibration) 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.

Then, as shown in FIG. 9, 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.

After blood removal begins, the load sensor 18 and calculation unit 25 calibrated in the calibration process (S3) calculate the flow ratio or blood removal pressure (S5), and the flow ratio or blood removal pressure is displayed on a monitor or the like for monitoring. After that, in S6, a value obtained by subtracting a predetermined value from the venous pressure after a period of time has elapsed (e.g., one minute) during which the venous pressure has stabilized is set as the reference point.

In S6, a reference point is set, and the process proceeds to S7, where it is determined whether the flow rate ratio or diastolic pressure calculated in S5 exceeds a preset value, and if it has fallen below the set value, the process proceeds to S8, where it is determined whether the venous pressure is below the reference point set in S6. If it has not fallen below the set value in S7, steps S8 to S11 are not performed, and treatment continues. If it is determined in S8 that the venous pressure is not below the reference point, the determination unit 28 determines that the detection value of the first detection unit is inappropriate, and the process proceeds to S9, where the notification unit 29 issues a specified notification (a notification that the detection value of the first detection unit is inappropriate or a notification suggesting this).

Then, in S11, a correction process is performed to correct the calibration curve D obtained in the initial calibration to obtain a corrected calibration curve E, and the corrected calibration curve E is used in subsequent dialysis treatments. If it is determined in S8 that the venous pressure is below the reference point, the judgment unit 28 determines that the detection value of the first detection unit is appropriate, and the process proceeds to S10, where the notification unit 29 issues a predetermined notification (a warning based on the detection value of the first detection unit). When the notification is issued in S10, the cause of the notification is removed (for example, the elimination of a bend in the blood circuit), and then treatment is continued. After the cause of the notification is removed, the venous pressure reference point may be reset.

After the correction process in S11 or the notification in S10, the process proceeds to S12, where it is determined whether the dialysis treatment has ended. If it is determined that the dialysis treatment has not ended, the process returns to S5, and monitoring of the flow rate ratio or the dialysis pressure using the corrected calibration curve E continues. On the other hand, if it is determined in S12 that the dialysis treatment has ended, the process proceeds to a blood return process S13 (a process of returning the blood in the blood circuit to the patient's body), and then a drainage process S14 is performed to drain the fluid from the dialyzer 3, and the series of controls ends. By going through the above series of processes, the flow rate ratio or the dialysis pressure can be detected in real time during dialysis treatment (blood purification treatment), and the flow rate ratio or the dialysis state can be monitored.

Next, experimental results of the blood purification apparatus according to this embodiment will be described with reference to the graphs in FIGS.
When the drive speed (flow rate) R1 of the blood pump 4 was set constant and the estimated blood flow rate R2, venous pressure R3, and dialysate pressure R4 calculated by the load sensor 18 and the calculation unit 25 were monitored, if the estimated blood flow rate R calculated by the load sensor 18 and the calculation unit 25 was not appropriate, as shown in FIG. 16 , the estimated blood flow rate R2 and the output voltage of the load sensor 18 decreased, whereas the venous pressure R3 and the dialysate pressure R4 did not decrease and remained constant.

When the estimated blood flow rate R calculated by the load sensor 18 and the calculation unit 25 is appropriate, as shown in FIG. 17, the venous pressure R3 and the dialysis fluid pressure R4 change (decrease) as the estimated blood flow rate R2 and the output voltage of the load sensor 18 decrease. Therefore, when the pressure detected by the second detection unit (in this experiment, the venous pressure sensor 7 and the dialysis fluid pressure sensor 20) changes as the detection value (estimated blood flow rate or estimated dialysis pressure) of the first detection unit (load sensor 18 and calculation unit 25) changes beyond a predetermined threshold, it can be determined that the detection value of the first detection unit is appropriate, and when the pressure detected by the second detection unit does not change as the detection value of the first detection unit changes beyond a predetermined threshold, it can be determined that the detection value of the first detection unit is inappropriate.

When the second detection unit is the inlet pressure sensor 8, the same tendency as the venous pressure sensor 7 and the dialysis fluid pressure sensor 20 is observed. Therefore, if the pressure detected by the inlet pressure sensor 8 as the second detection unit changes as the detection value (estimated blood flow rate or estimated dialysis pressure) of the first detection unit (load sensor 18 and calculation unit 25) changes beyond a predetermined threshold, it can be determined that the detection value of the first detection unit is appropriate. Conversely, if the pressure detected by the inlet pressure sensor 8 does not change as the detection value of the first detection unit changes beyond a predetermined threshold, it can be determined that the detection value of the first detection unit is inappropriate.

According to this embodiment, when the detection value of the first detection unit changes beyond a predetermined threshold, it is compared with the change in pressure detected by the second detection unit to determine whether the detection value of the first detection unit is appropriate. This makes it possible to determine whether a false detection occurred due to a decrease in the reaction force (repulsive force caused by elasticity) of the flexible tube at the detection position as the blood purification treatment progresses, and allows for smooth response when the detection value of the first detection unit changes.

The blood pump 4 is a squeeze type pump that compresses the squeezed part of the blood circuit (squeezed tube 1a) radially with the squeeze part (roller 10) while squeezing it longitudinally to pump fluid. The first detection unit detects radial displacement at a detection position upstream of the part squeezed by the squeeze part (the tip side of the arterial blood circuit 1), so that the actual blood flow rate and the deficiency of the diaphragm pressure relative to the set blood flow rate can be accurately estimated.

The blood circuit is composed of an arterial blood circuit 1 for drawing blood from the patient and a venous blood circuit 2 for returning blood to the patient, and the second detection unit is composed of an inlet pressure sensor 8 arranged in the arterial blood circuit 1 for detecting the inlet pressure of the dialyzer 3, a venous pressure sensor 7 arranged in the venous blood circuit 2 for detecting the venous pressure, or a dialysis fluid pressure sensor 20 for detecting the fluid pressure of the dialysis fluid in the drainage discharge line L2, so that the sensors required for blood purification treatment can be reused and used as the second detection unit.

Furthermore, the judgment unit 28 judges that the detection value of the first detection unit is appropriate if the pressure detected by the second detection unit changes as the detection value of the first detection unit changes beyond a predetermined threshold, and judges that the detection value of the first detection unit is inappropriate if the pressure detected by the second detection unit does not change as the detection value of the first detection unit changes beyond a predetermined threshold, so that the appropriateness of the detection value of the first detection unit can be judged accurately and quickly.

In addition, if the judgment unit 28 judges that the detection value of the first detection unit is appropriate, an alarm based on the detection value of the first detection unit is issued, and if the judgment unit 28 judges that the detection value of the first detection unit is inappropriate, a notification unit 29 is provided that notifies the user that the detection value of the first detection unit is inappropriate or gives a suggestion thereto. Therefore, if there is a high possibility of erroneous detection, the notification can be given and a suggestion thereto, allowing the user to take action more quickly when the detection value of the first detection unit changes.

In addition, before blood is circulated extracorporeally in the blood circuit to perform blood purification treatment, the first detection unit is initially calibrated to obtain a calibration curve D, and if the judgment unit 28 judges that the detection value of the first detection unit is inappropriate, the calibration curve D obtained by the initial calibration is corrected, so that detection by the first detection unit after the correction of the calibration curve D can be performed with high accuracy. In particular, since the calibration curve D is corrected based on the detection value of the first detection unit when the driving amount of the blood pump 4 is reduced or stopped, it is possible to avoid the generation of excessive negative pressure in the blood circuit during blood purification treatment.

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

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 that biases the gripping piece 14 toward the ironed tube 1a. The load sensor 18, which serves as the first 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 both generate a gripping force on the ironed tube 1a and detect the pressure of the arterial blood circuit 1.

Although the present embodiment has been described above, the present invention is not limited to this, and for example, a blood pump 4 shown in Figures 18 and 19 may be used. As shown in the figure, such a blood pump 4 is mainly composed of a stator 8, a rotor 9 that can be rotated within the stator 8, a roller 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 first detection portion.

The upstream gripping portion 12 is for gripping the upstream side (the portion to which the tip side of the arterial blood circuit 1 is connected) of the ironed tube 1a attached to the mounting recess Ga of the stator 8 in the blood pump 4, and as shown in FIG. 19, it has a gripping piece 14 that can grip the ironed tube 1a by pressing it radially, and a torsion spring 15 that biases the gripping piece 14 toward the ironed tube 1a.

The pressure transducer 30 constituting the first detection section is capable of detecting the radial displacement of the portion of the ironed tube 1a gripped by the upstream gripping section 12. In this embodiment, it is disposed at a portion facing 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.

In other words, 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 squeezed tube 1a drops, and the part of the squeezed tube 1a gripped by the upstream gripping portion 12 tries to displace radially (it flattens and the diameter on the short axis tends to become smaller), causing a drop in the pressure detected by the pressure transducer 30. By detecting this drop in pressure, it is possible to detect the generation of negative pressure in the arterial blood circuit 1.

The pressure transducer 30 according to this embodiment, like the previous embodiment, is electrically connected to the calculation unit 25 by extending wiring, etc. The calculation unit 25 constitutes the first detection unit together with the calculation unit 25, and is composed of a microcomputer or the like disposed in the dialysis device body, for example, and is configured to be able to calculate the pressure and flow rate ratio of the arterial blood circuit 1 (liquid flow path) based on the radial displacement of the ironing tube 1a detected by the pressure transducer 30.

The calibration curve D obtained by the calibration curve creation unit 27 is used to calibrate the pressure transducer 30 and the calculation unit 25. Note that instead of the load sensor 18 and pressure transducer 30 attached to the blood pump 4, other types of sensors may be used, or a sensor may be attached to a location separate from the blood pump 4.

The second detection unit is not limited to the venous pressure sensor 7, the inlet pressure sensor 8, and the dialysis fluid pressure sensor 20, but may be another pressure sensor whose detection value changes in response to a change in the detection value of the first detection unit. The second detection unit is sufficient as long as it detects the flow rate or pressure of either the liquid downstream of the detection position in the blood circuit or the dialysis fluid in the piping. Furthermore, it can be applied to other types of blood circuits (including those with other types of blood purifiers instead of the dialyzer 3) and dialysis device main bodies (including those with a chamber system instead of the duplex pump 21).

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 products with added functions.

1 Arterial blood circuit (liquid flow path)
1a Covered tube (covered part)
2 Venous blood circuit 3 Dialyzer (blood purifier)
4 Blood pump 5 Arterial air trap chamber 6 Venous air trap chamber 7 Venous pressure sensor 8 Inlet pressure sensor 9 Rotor 10 Roller (squeezing part)
11 Guide pin 12 Upstream gripping portion 13 Downstream gripping portion 14 Grip piece 15 Torsion spring 16 Grip piece 17 Torsion spring 18 Load sensor (first detection portion)
19 Collection port 20 Dialysis fluid pressure sensor 21 Duplex pump 22 Water removal pump 23 Filtration filter 24 Filtration filter 25 Calculation unit (first detection unit)
26 Control unit 27 Calibration curve acquisition unit 28 Determination unit 29 Notification unit 30 Pressure transducer L1 Dialysis fluid introduction line (piping section)
L2 Drainage discharge line (piping section)
L3 Dialysis fluid supply line L4 Overflow lines L5-L8 Bypass line G Stator Ga Mounting recesses V1-V9 Solenoid valve D Calibration curve (initial calibration)
E. Calibration curve (after correction)

Claims (7)

A blood purification device that circulates a patient's blood extracorporeally through a blood purifier and a blood circuit, and purifies the blood,
a blood pump for pumping blood through the blood circuit;
a piping section having a dialysis fluid introduction line for introducing a dialysis fluid into the blood purifier and a waste fluid discharge line for discharging a waste fluid from the blood purifier;
A first detection unit that is disposed at a predetermined detection position in the blood circuit and detects a flow rate or a pressure of a liquid;
a second detection unit that detects a flow rate or a pressure of either a liquid downstream of the detection position in the blood circuit or a dialysis fluid in the piping;
a determination unit that determines whether the detection value of the first detection unit is appropriate based on a change in flow rate or pressure detected by the second detection unit when the detection value of the first detection unit reaches a predetermined threshold value;
and correcting the detection value of the first detection unit when the determination unit determines that the detection value of the first detection unit is inappropriate . the blood pump is a peristaltic pump that pumps liquid by compressing a covered part of the blood circuit in a radial direction with a peristaltic part while peristalticing the covered part in a longitudinal direction,
2. The blood purification device according to claim 1, further comprising a gripping piece configured to be swingable around a predetermined axis and gripping the squeezing portion at one end thereof, wherein the first detection unit has a load sensor that receives a load from the other end of the gripping piece, and the load sensor detects the load applied by the gripping piece that swings in response to radial displacement of the squeezing portion at the detection position upstream of a site squeezed by the squeezing portion in the fluid sending direction of the blood circuit. The blood purification device according to claim 1 or 2, wherein the blood circuit is configured with an arterial blood circuit for removing blood from the patient and a venous blood circuit for returning blood to the patient, and the second detection unit is comprised of an inlet pressure sensor arranged in the arterial blood circuit for detecting the inlet pressure of the blood purifier, a venous pressure sensor arranged in the venous blood circuit for detecting the venous pressure, or a dialysis fluid pressure sensor for detecting the fluid pressure of the dialysis fluid in the drainage discharge line. The blood purification device according to any one of claims 1 to 3, wherein the judgment unit judges that the detection value of the first detection unit is appropriate when the pressure detected by the second detection unit changes as the detection value of the first detection unit reaches a predetermined threshold, and judges that the detection value of the first detection unit is inappropriate when the pressure detected by the second detection unit does not change as the detection value of the first detection unit reaches a predetermined threshold. The blood purification device according to any one of claims 1 to 4, further comprising a notification unit that issues an alarm based on the detection value of the first detection unit when the determination unit determines that the detection value of the first detection unit is appropriate, and that issues a notification indicating that the detection value of the first detection unit is inappropriate or a suggestion thereof when the determination unit determines that the detection value of the first detection unit is inappropriate. 2. The blood purification device according to claim 1, wherein, before blood is circulated extracorporeally in the blood circuit to perform blood purification treatment, the first detection unit is initially calibrated to obtain a calibration curve, and when the judgment unit judges that the detection value of the first detection unit is inappropriate, the detection value of the first detection unit is corrected by correcting the calibration curve obtained by the initial calibration. 7. The blood purification apparatus according to claim 6 , wherein the calibration curve is corrected based on the detection value of the first detection unit when the driving amount of the blood pump is reduced or stopped.

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