Hemodialysis device

Abstract

A hemodialysis device (1) for quickly stabilizing fluid infusion when pressure fluctuations suddenly occur is provided with a fluid infusion passage (5) between a dialysate circuit (4) and a blood circuit (3), and first and second flow rate restricting means (MV1, MV2) are provided in the dialysate circuit (4) and the fluid infusion passage (5), respectively, and is provided with: a connection part pressure sensor (PG2) that detects the fluid infusion pressure in the dialysate circuit (4) and the fluid infusion passage (5), and that detects the fluid infusion pressure in the blood circuit (3) by means of the first and second flow rate restricting means (MV1, MV2); measuring the pressure of a connection portion between the dialysate supply passage (14) and the fluid replacement passage (5); and a vein-side pressure sensor (PV) (blood circuit pressure measurement means) that measures the pressure of the blood circuit (3), and a control means (6) that controls the pressure of the blood circuit (3) during a single cycle from a state in which a supply chamber provided in the cavity of the dialysate circuit (4) is filled with fresh dialysate to a state in which all fresh dialysate in the supply chamber is discharged. On the basis of the pressure measured by the connection part pressure sensor (PG2) and the pressure measured by the vein-side pressure sensor (PV), the opening degree of the second flow rate restriction means (MV2) is adjusted a plurality of times.

Description

Technical Field

[0001] The present invention relates to a hemodialysis device, and more particularly to a hemodialysis device that performs fluid replenishment via a fluid replenishment passage provided between a dialysate circuit and a blood circuit. Background Art

[0002] Conventionally, in hemodialysis using a hemodialysis device, fluid replenishment is performed via a fluid replenishment passage provided between a dialysate circuit and a blood circuit. As a hemodialysis device that performs such fluid replenishment, an example is known in which first and second flow restrictors are provided in the dialysate circuit and the fluid replenishment passage, respectively (Patent Document 1).

[0003] In Patent Document 1 described above, the control unit controls the first and second flow restrictors so that the pressure at the connection portion between the dialysate supply passage and the fluid replenishment passage is higher than the pressure in the blood circuit, and supplies the dialysate in the dialysate circuit to the blood circuit.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2021-62067 Summary of the Invention

[0007] However, in Patent Document 1 described above, a sudden pressure change in the blood circuit is not assumed, for example, a so-called kink in which a tube constituting the blood circuit is bent due to a change in the patient's body posture or the like.

[0008] For example, when the kink occurs on the upstream side of the connection portion between the blood circuit and the fluid replenishment passage, the pressure on the downstream side of the connection portion becomes relatively negative, so there is a possibility that more dialysate than the preset target fluid replenishment flow rate flows into the blood circuit. In this case, it is necessary to quickly stabilize the fluid replenishment.

[0009] In view of such problems, the present invention provides a hemodialysis device that can quickly stabilize fluid replenishment even when a pressure change suddenly occurs in the blood circuit.

[0010] The hemodialysis device according to an aspect of the invention is characterized by comprising:

[0011] A dialyzer for performing hemodialysis; a chamber provided in a dialysate circuit for containing dialysate; a fresh dialysate supply passage connected to a supply chamber of the chamber for supplying fresh dialysate to the dialyzer; a used dialysate recovery passage connected to a recovery chamber of the chamber for recovering used dialysate that has flowed through the dialyzer; a blood circuit for allowing blood to flow through the dialyzer; a fluid replenishment passage provided between the fresh dialysate supply passage and the blood circuit; a first flow restrictor unit provided on the downstream side of a connection portion of the fresh dialysate supply passage with the fluid replenishment passage; a second flow restrictor unit provided in the fluid replenishment passage; and a control unit for controlling the first flow restrictor unit and the second flow restrictor unit,

[0012] By controlling the first flow restrictor unit and the second flow restrictor unit by the control unit, the fluid replenishment flow rate supplied to the blood circuit via the fluid replenishment passage is adjusted.

[0013] The hemodialysis device includes: a connection portion pressure measurement unit for measuring the pressure at a connection portion between the fresh dialysate supply passage and the fluid replenishment passage; and a blood circuit pressure measurement unit for measuring the pressure of the blood circuit.

[0014] During one cycle from a state where the supply chamber of the chamber is filled with fresh dialysate to a state where all the fresh dialysate in the supply chamber is discharged, the control unit performs feedback control for adjusting the second flow restrictor unit multiple times according to a target fluid replenishment flow rate, the measured pressure of the connection portion pressure measurement unit, and the measured pressure of the blood circuit pressure measurement unit.

[0015] According to an aspect of the invention, by performing feedback control for the second flow restrictor unit multiple times during one cycle, even if a sudden pressure change occurs, stable fluid replenishment can be achieved because the fluid replenishment flow rate is adjusted quickly. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a circuit diagram showing an embodiment of the present invention.

[0017] Figure 2 is a diagram for explaining the operation in the case where only the second feedback control is performed in the present embodiment.

[0018] Figure 3 is a diagram for explaining the operation in the case where the first and second feedback controls are performed in the present embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] Hereinafter, when explaining the present invention with respect to the illustrated embodiments, Figure 1In this case, the hemodialysis device 1 includes a blood circuit 3 that is connected to the dialyzer 2 and through which blood flows, a dialysate circuit 4 that is connected to the dialyzer 2 and through which dialysate flows, and a fluid replenishment passage 5 that connects the blood circuit 3 and the dialysate circuit 4.

[0020] The above-mentioned hemodialysis device 1 is controlled by a control unit 6. As an example of the control unit 6, it is possible to use a personal computer, a microcomputer, a PLC, etc. with a built-in microprocessor and control each device constituting the above-mentioned hemodialysis device 1 through a user-changeable program.

[0021] The above-mentioned blood circuit 3 includes an arterial-side passage 7 that is connected to the patient's blood vessel and supplies blood to the above-mentioned dialyzer 2, and a venous-side passage 8 that returns blood from the dialyzer 2 to the patient.

[0022] For the above-mentioned arterial-side passage 7, its tip is punctured into the patient's artery, and its base end is connected to the inlet of the dialyzer 2. In addition, an arterial-side pressure sensor PA and a blood pump 9 for transferring blood are provided in the arterial-side passage 7.

[0023] The base end of the above-mentioned venous-side passage 8 is connected to the outlet of the above-mentioned dialyzer 2, and its tip is punctured into the patient's vein. In addition, a drip chamber 10 is provided in the venous-side passage 8, and a venous-side pressure sensor PV as a blood circuit pressure measuring unit is provided in the drip chamber 10.

[0024] In the above-mentioned dialysate circuit 4, a first chamber 11 and a second chamber 12 of the same shape for accommodating dialysate are provided. Regarding these first and second chambers 11 and 12, their interiors are divided into two chambers by a flexible diaphragm. One becomes a supply chamber 11A, 12A for accommodating fresh dialysate, and the other becomes a recovery chamber 11B, 12B for recovering the used dialysate.

[0025] Moreover, a liquid supply passage 13 supplied with fresh dialysate and a dialysate supply passage 14 for supplying the fresh dialysate to the dialyzer 2 are respectively branched and connected to the above-mentioned supply chambers 11A, 12A. Liquid supply valves V1, V2 are provided in the branched passages of the liquid supply passage 13, and supply valves V3, V4 are provided in the branched passages of the dialysate supply passage 14.

[0026] A dialysate recovery passage 15 for recovering the used dialysate flowing in the dialyzer 2 and a drain passage 16 for discharging the used dialysate are connected to the above-mentioned recovery chambers 11B, 12B. Recovery valves V5, V6 are provided in the branched passages of the dialysate recovery passage 15, and drain valves V7, V8 are provided in the branched passages of the drain passage 16.

[0027] A fresh dialysate supply device (not shown) for supplying fresh dialysate to the upstream side thereof is provided in the above-mentioned liquid supply passage 13, and a liquid supply pump 17 and a liquid supply pressure sensor PG1 are provided between the first and second chambers 11 and 12.

[0028] A first end cut-off filter F1, a second end toxin cut-off filter F2 for purifying the dialysate, and a connection part pressure sensor PG2 as the connection part pressure measurement unit of the present invention are provided in the above-mentioned dialysate supply passage 14, and the above-mentioned liquid replenishment passage 5 is connected to the downstream side of the connection part pressure sensor PG2.

[0029] In addition, a first flow throttle unit MV1, a flowmeter 18, and an on-off valve V9 controlled by the control unit 6 are provided on the downstream side of the connection part of the dialysate supply passage 14 with the above-mentioned liquid replenishment passage 5.

[0030] The liquid replenishment passage 5 of the present embodiment is constituted by connecting the pipes branched from the dialysate circuit 4 and the blood circuit 3 to each other.

[0031] Specifically, the liquid replenishment passage 5a on the dialysate circuit 4 side is branched and provided as described above between the connection part pressure sensor PG2 and the first flow throttle unit MV1 in the above-mentioned dialysate supply passage 14.

[0032] A second flow throttle unit MV2, an on-off valve V10, and a connection port 19 for connecting to the liquid replenishment passage 5 on the above-mentioned blood circuit 3 side are provided in the liquid replenishment passage 5 on the dialysate circuit 4 side and are controlled by the control unit 6.

[0033] On the other hand, the liquid replenishment passage 5b on the blood circuit 3 side is branched from between the dialyzer 2 and the drip chamber 10 in the above-mentioned venous side passage 8, and the top end is connected to the above-mentioned connection port 19.

[0034] In the liquid replenishment passage 5b on the blood circuit 3 side, a check valve 20 for preventing the backflow of blood from the blood circuit 3 is provided at a position adjacent to the branch portion.

[0035] Here, the pipe structure in which the liquid replenishment passage 5b branches from the venous side passage 8 is called postconnection, and the pipe structure in which the liquid replenishment passage 5b branches from the arterial side passage 7 as shown by the dotted line is called preconnection, and the feedback control of the present invention can cope with any connection method.

[0036] In the present embodiment, as the above-mentioned first and second flow throttle units MV1 and MV2, conventionally known diaphragm valves that can be controlled by the control unit 6 are used.

[0037] The flow throttling unit using the diaphragm valve adjusts the flow rate of the dialysate in circulation by increasing or decreasing the lift amount of the diaphragm valve with respect to the valve seat, thereby increasing or decreasing the flow path area. The lift amount can be adjusted by the voltage applied using the control unit 6.

[0038] In the above-mentioned dialysate recovery passage 15, an on-off valve V11, a first recovery-side pressure sensor PG3, a degassing tank 21 for removing air bubbles from the dialysate, a liquid feed pump 22 for sending the used dialysate to the respective recovery chambers 11B and 12B of the first and second chambers 11 and 12, and a second recovery-side pressure sensor PG4 are provided in sequence from the upstream side on the dialyzer 2 side.

[0039] A water removal passage 23 is connected between the above-mentioned liquid feed pump 22 and the second recovery-side pressure sensor PG4, and a required amount of the used dialysate is discharged to the drainage passage 16 via a water removal pump 24 provided in the water removal passage 23 to perform water removal during dialysis treatment.

[0040] The operation of the hemodialysis device 1 having the above structure will be described. In addition, in the following description, the replenishment operation will be mainly described, and detailed descriptions of other operations are omitted because they are well-known in the past.

[0041] First, before starting hemodialysis using the hemodialysis device 1, the arterial-side passage 7 and the venous-side passage 8 of the blood circuit 3 are respectively connected to the patient, and various settings are made in advance.

[0042] In the present embodiment, the doctor sets the dialysate flow rate and the replenishment flow rate according to the patient's physical condition, etc. Here, as an example, the target dialysate flow rate Dtf of the fresh dialysate flowing from the above-mentioned dialysate supply passage 14 to the dialyzer 2 is set to 700 ml / min, and the target replenishment flow rate Stf for replenishing the patient via the replenishment passage 5 is set to 100 ml / min.

[0043] When such settings are completed and a start instruction for hemodialysis is input to the control unit 6, in the dialysate circuit 4, fresh dialysate is supplied from the above-mentioned supply passage 13 to the supply chamber 11A of the first chamber 11, and the volume of the supply chamber 11A expands due to the deformation of the diaphragm. Along with this, the volume of the recovery chamber 11B shrinks, and the used dialysate accommodated in the recovery chamber 11B is discharged to the drainage passage 16.

[0044] At the same time, the used dialysate after passing through the dialyzer 2 flows in the dialysate recovery passage 15 and is recovered into the recovery chamber 12B of the second chamber 12. Along with this, due to the deformation of the diaphragm, the fresh dialysate in the supply chamber 12A is supplied to the dialyzer 2 via the dialysate supply passage 14.

[0045] After that, the control unit 6 alternately supplies fresh dialysate to the dialyzer 2 from the first and second chambers 11 and 12 by switching the opening and closing states of the above-mentioned liquid supply valves V1, V2 and the liquid discharge valves V7, V8, and the supply valves V3, V4 and the recovery valves V5, V6.

[0046] Here, for example, the period from the state where the volume of the supply chamber 11A in the first chamber 11 becomes the maximum to the state where all the fresh dialysate in the supply chamber 11A is discharged and the volume becomes zero is defined as one cycle.

[0047] The second recovery side pressure sensor PG4 provided in the above-mentioned dialysate recovery passage 15 can be used to detect the time interval required for the above one cycle.

[0048] When specifically described, when the used dialysate flows into the recovery chamber 12B of the second chamber 12, and then the volume of the supply chamber 12A becomes zero due to the deformation of the diaphragm, a pressure wave (water hammer) is generated, and this shock wave is detected by the above-mentioned second recovery side pressure sensor PG4.

[0049] Then, the control unit 6 identifies that the liquid supply of the dialysate from the second chamber 12 has been completed, switches the recovery valves V5, V6 and the liquid discharge valves V7, V8 of the above-mentioned first and second chambers 11, 12, and sets the time point when the liquid supply starts from the supply chamber 11A of the first chamber 1 as the liquid supply start time point.

[0050] After that, when it is detected by the above-mentioned second recovery side pressure sensor PG4 that the liquid supply from the supply chamber 11A of the first chamber 11 has been completed, this time point is identified as the liquid supply completion time point.

[0051] In this way, the control unit 6 identifies the time interval from the liquid supply start time point of the supply chamber 11A of the above-mentioned first chamber 11 to the liquid supply start time point of the supply chamber 12A of the second chamber 12 as one cycle.

[0052] In other words, one cycle means the period from the time point when the liquid supply of the supply chamber of one chamber starts until the time point when the liquid supply of the supply chamber of the other chamber starts after the inflow of the used dialysate into the recovery chamber of one chamber is completed.

[0053] Next, in the hemodialysis device 1, when replenishing the patient during dialysis treatment, the control unit 6 opens the on-off valve V10 provided in the replenishment passage 5. Then, a part of the dialysate supplied from the dialysate supply passage 14 to the dialyzer 2 is supplied to the blood circuit 3 via the replenishment passage 5 to perform replenishment for the patient.

[0054] At this time, the control unit 6 controls the first flow throttle unit MV1 provided in the dialysate supply passage 14 and the second flow throttle unit MV2 provided in the replenishing liquid passage 5, so that the dialysate of the above-mentioned target replenishing liquid flow rate Stf flows into the replenishing liquid passage 5.

[0055] Moreover, the dialysate flowing from the replenishing liquid passage 5 into the blood circuit 3 is supplied as a replenishing liquid to the patient. At this time, the check valve 20 provided in the above-mentioned replenishing liquid passage 5 is used to prevent the reverse flow from the blood circuit 3 to the replenishing liquid passage 5.

[0056] Here, when supplying dialysate from the dialysate circuit 4 to the blood circuit 3 via the above-mentioned replenishing liquid passage 5, due to the change in the pressure of the blood flowing in the blood circuit 3, the replenishing liquid flow rate flowing from the replenishing liquid passage 5 into the blood circuit 3 sometimes changes.

[0057] For example, when the pressure of the blood flowing in the blood circuit 3 is high, the inflow of the dialysate from the replenishing liquid passage 5 is obstructed, so the replenishing liquid of the dialysate less than the target replenishing liquid flow rate Stf is performed. On the other hand, when the pressure of the blood flowing in the blood circuit 3 is low, the dialysate flows in too much from the replenishing liquid passage 5, and the replenishing liquid of the dialysate more than the target replenishing liquid flow rate Stf is performed.

[0058] As factors for such a change in the pressure of the blood flowing in the blood circuit 3, the blood pressure of the patient and the liquid delivery volume of the blood pump 9 provided in the above-mentioned blood circuit 3 are considered. However, in addition to this, the situation where the blood flow is suddenly obstructed due to the bending of the tube constituting the blood circuit 3, which is called a so-called kink, is also considered.

[0059] When the above-mentioned kink occurs on the upstream side of the connection part of the blood circuit 3 and the replenishing liquid passage 5, the pressure of the blood in the above-mentioned connection part becomes relatively negative, so too much dialysate flows in from the replenishing liquid passage 5.

[0060] In contrast, when the above-mentioned kink occurs on the downstream side of the connection part with the replenishing liquid passage 5, the pressure of the blood in the above-mentioned connection part becomes relatively positive, so the inflow of the dialysate from the replenishing liquid passage 5 is obstructed.

[0061] Even when such a sudden pressure change occurs in the blood circuit 3 of the hemodialysis device 1 of the present embodiment, the first flow throttle unit MV1 and the second flow throttle unit MV2 are quickly subjected to feedback control to stabilize the replenishing liquid flow rate.

[0062] In the present embodiment, two types of feedback control are performed on the above-mentioned first and second flow throttle units MV1 and MV2. Figure 2 The case where only the second feedback control is performed is shown, Figure 3 The case where the first feedback control and the second feedback control are performed is shown.

[0063] In Figure 2 and Figure 3 on the horizontal axis, the passage of time is represented, and one cycle from the state where the volume of the supply chamber 11A (supply chamber 12A) of the first chamber 11 (second chamber 12) becomes the maximum until the time point when the volume of the supply chamber 12A (supply chamber 11A) of the second chamber 12 (first chamber 11) becomes the maximum and the supply starts is repeated for the first to third cycles.

[0064] On the vertical axis, the infusion flow rate (mL / min) flowing into the blood circuit 3 via the infusion passage 5, the opening degree of the second flow throttle unit MV2 provided in the infusion passage 5, and the pressure (Pa) of the blood circuit 3 measured by the venous side pressure sensor PV are shown.

[0065] The first feedback control is a control that adjusts the opening degrees of the first and second flow throttle units MV1 and MV2 multiple times during one cycle, and in particular, responds to sudden pressure changes such as kinking. In Figure 3 the opening degree of the second flow throttle unit MV2 using the first feedback control is indicated by a white diamond.

[0066] Here, the purpose of the first feedback control is to stabilize the infusion flow rate within the cycle by controlling in such a way as to maintain the cycle-set infusion flow rate Ssfr set by the second feedback control even when a sudden change occurs in the differential pressure between the blood circuit 3 and the dialysate circuit 4 during this cycle.

[0067] Here, as a cause of a sudden change in the differential pressure between the blood circuit 3 and the dialysate circuit 4, there is a so-called kink where the piping constituting the blood circuit 3 is bent and the blood flow is obstructed, but in addition to this, it may also occur due to a change in the posture of the patient to whom the blood circuit 3 is connected.

[0068] In contrast, in the second feedback control, the opening degrees of the first and second flow throttle units MV1 and MV2 are adjusted for each cycle, and the target dialysate flow rate Dtf and the target infusion flow rate Stf are updated for each cycle. In Figure 2 and Figure 3 the opening degree of the second flow throttle unit MV2 using the second feedback control is indicated by a black square.

[0069] Here, the purpose of the second feedback control is as follows.

[0070] First, in order to achieve the target dialysate flow rate Dtf and the target infusion flow rate Stf preset by a doctor or the like, the opening degrees of the first and second flow throttle units MV1 and MV2 are determined in advance.

[0071] However, when operating the hemodialysis device 1, due to various factors (such as deviations in pressure loss caused by manufacturing errors of structural parts of the fluid circuit (solenoid valves, various filters, flow meters, etc.), manufacturing errors in the length of the tubes, temperature during operation, dialysate concentration, etc.), the actually flowing dialysate flow rate and the replacement fluid flow rate will deviate from the above target values respectively.

[0072] Therefore, in the second feedback control, every time one cycle ends after the start of dialysis treatment, the dialysate flow rate and the replacement fluid flow rate actually flowing in that cycle are measured, and the offsets of these values from the above target dialysate flow rate and target replacement fluid flow rate are fed back in the next cycle.

[0073] Thus, at the beginning of dialysis treatment, due to the influence of the above variable factors, the replacement fluid flow rate deviates from the target value, but by implementing the second feedback control, every time a cycle passes, it converges towards the target replacement fluid flow rate Stf.

[0074] First, an explanation is given using Figure 2 the above second feedback control. In the control unit 6, the target dialysate flow rate Dtf (mL / min) supplied to the dialyzer 2 via the dialysate supply passage 14 and the target replacement fluid flow rate Stf (mL / min) for replenishing the patient via the replacement fluid passage 5 are preset in advance.

[0075] In the present embodiment, as an example, the target dialysate flow rate Dtf is set to 700 (mL / min), and the target replacement fluid flow rate Stf is set to 100 (mL / min).

[0076] First, the control unit 6 measures the dialysate flow rate supplied from the above dialysate supply passage 14 towards the dialyzer 2 using the above flow meter 18, and calculates the actual dialysate flow rate Dafr (mL / min) per cycle as the average flow rate for each cycle.

[0077] In addition, for each cycle, the control unit 6 corrects the set dialysate flow rate Dsfr for the cycle based on the above target dialysate flow rate Dtf.

[0078] (Equation 1)

[0079] The corrected set dialysate flow rate Dsfr = target dialysate flow rate Dtf + the set dialysate flow rate Dsfr for this cycle - the actual dialysate flow rate Dafr for this cycle

[0080] In the above Equation 1, the corrected set dialysate flow rate Dsfr refers to the set dialysate flow rate Dsfr that the control unit 6 sets in the next cycle, and the set dialysate flow rate Dsfr for this cycle corresponds to the set dialysate flow rate Dsfr that the control unit 6 set in the previous cycle.

[0081] In addition, when this is the initial cycle, the set dialysate flow rate Dsfr of this cycle becomes the same value as the above-mentioned target dialysate flow rate Dtf set in advance.

[0082] For example, when the target dialysate flow rate Dtf is registered as 700 (mL / min) and the actual dialysate flow rate Dafr in the first cycle is 690 (mL / min), using Equation 1, the set dialysate flow rate Dsfr of the second cycle is calculated as follows.

[0083] 700 (mL / min) + 700 (mL / min) - 690 (mL / min) = 710 (mL / min)

[0084] In addition, in the control unit 6, for the first feedback control described below, the following calculation is performed.

[0085] (Equation 2)

[0086] Dialysate correction amount Dc = corrected set dialysate flow rate Dsfr - target dialysate flow rate Dtf

[0087] According to this Equation 2, the dialysate correction amount Dc is calculated as follows.

[0088] 710 (mL / min) - 700 (mL / min) = 10 (mL / min)

[0089] After calculating the set dialysate flow rate Dsfr in this way, the control unit 6 performs feedback control on the first flow throttling unit MV1 so as to obtain the calculated set dialysate flow rate Dsfr at the start time point of each cycle.

[0090] The control unit 6 uses the following Equation 3 to calculate the dialysate pressure loss DL generated when the dialysate flows through the first flow throttling unit MV1.

[0091] (Equation 3)

[0092] Dialysate pressure loss DL = connection part pressure PG2 - dialysate pressure PG3 - γ

[0093] Here, the connection part pressure PG2 represents the pressure value measured by the connection part pressure sensor PG2 provided in the above-mentioned dialysate supply passage 14, and the dialysate pressure PG3 represents the pressure value measured by the first recovery side pressure sensor PG3 provided in the above-mentioned dialysate recovery passage 15.

[0094] In addition, γ in the above formula 3 is a value that takes into account the pressure loss (Pa) caused by other elements (flow meter 18, on-off valve V9, dialyzer 2, etc.) in the path from the first flow throttle unit MV1 to the connection part pressure sensor PG2, the weight of the dialysate in the pipe constituting this section, and so on.

[0095] Moreover, in the second feedback control, regarding the connection part pressure PG2 and the dialysate pressure PG3, the pressure values at the end of one cycle are used. Therefore, the dialysate pressure loss DL calculated using the above formula 3 becomes the cyclic dialysate pressure loss DLr calculated for each cycle.

[0096] After obtaining the cyclic dialysate pressure loss DLr in this way, the dialysate pressure loss coefficient ζD is then calculated using the following formula 4.

[0097] [Formula 4]

[0098]

[0099] Here, the dialysate flow velocity (m / s) in the above formula 4 can be calculated by dividing the cyclic actual dialysate flow rate Dafr measured by the above flow meter 18 by the cross-sectional area of the pipe constituting the dialysate circuit 4.

[0100] Moreover, in the second feedback control, the measured values at the end of one cycle are used as the connection part pressure PG2 and the dialysate pressure PG3. Therefore, the dialysate pressure loss coefficient ζD calculated using the above formula 4 becomes the cyclic dialysate pressure loss coefficient ζDr calculated for each cycle.

[0101] Moreover, the first command voltage V1 for controlling the first flow throttle unit MV1 can be calculated by substituting the cyclic dialysate pressure loss coefficient ζDr into the following formula 5.

[0102] (Formula 5)

[0103] First command voltage V1u = -α + ln (dialysate pressure loss coefficient ζD) + β

[0104] Here, α and β in formula 5 are constants.

[0105] In the second feedback control, the first flow throttle unit MV1 is controlled at the end of one cycle. Therefore, the first command voltage V1 calculated using the above formula 5 becomes the cyclic first command voltage V1r calculated for each cycle.

[0106] After calculating the first command voltage V1r of the cycle in this way, at the end time point of this cycle, that is, the start time point of the next cycle, the control unit 6 applies the first command voltage V1r of the cycle to the first flow throttle unit MV1, and controls the opening degree of the first flow throttle unit MV1 (omitted in Figure 2 ).

[0107] Next, in the second feedback control, the first command voltage V1r for controlling the first flow throttle unit MV1 is calculated. On the other hand, the target replenishing fluid flow rate Stf is corrected according to the following process, and the second command voltage V2 for controlling the second flow throttle unit MV2 is calculated.

[0108] First, in the control unit 6, as the replenishing fluid flow rate flowing in the replenishing fluid passage 5, the following formula 6 is used to calculate the actual replenishing fluid flow rate Safr (mL / min) in one cycle.

[0109] (Formula 6)

[0110] Actual replenishing fluid flow rate Safr = Total dialysis fluid flow rate Dtf - Actual dialysis fluid flow rate Dafr in the cycle

[0111] Here, the total dialysis fluid flow rate Dtf (mL / min) can be calculated based on the volume of the cavity and the time interval (fluid delivery time) required for one cycle. In addition, the actual dialysis fluid flow rate Dafr (mL / min) is the average flow rate in one cycle measured by the flow meter 18.

[0112] Next, the control unit 6 uses the following formula 7 to correct the set replenishing fluid flow rate Ssfr for each cycle.

[0113] (Formula 7)

[0114] Corrected set replenishing fluid flow rate Ssfr = Ssfr of this cycle + Target replenishing fluid flow rate Stf - Actual replenishing fluid flow rate Safr

[0115] In the above formula 7, the corrected set replenishing fluid flow rate Ssfr refers to the set replenishing fluid flow rate Ssfr that the control unit 6 sets in the next cycle, and the set replenishing fluid flow rate Ssfr of this cycle is equivalent to the set replenishing fluid flow rate Ssfr that the control unit 6 set in the previous cycle.

[0116] In addition, when this cycle is the first cycle, the set replenishing fluid flow rate Ssfr of this cycle becomes the same value as the above-mentioned target replenishing fluid flow rate Stf set in advance.

[0117] For example, when the target replenishing fluid flow rate Stf is registered as 100 (mL / min) and the actual circulating actual replenishing fluid flow rate Safr in the first cycle is 110 (mL / min), according to Equation 7, the circulating set replenishing fluid flow rate Ssfr for the second cycle is calculated as follows.

[0118] 90 (mL / min) = 100 (mL / min) + 100 (mL / min) - 110 (mL / min)

[0119] That is, the corrected circulating set replenishing fluid flow rate Ssfr set in the second cycle becomes 90 (mL / min), and when the control unit 6 starts the second cycle as shown Figure 2 it is updated to the calculated corrected circulating set replenishing fluid flow rate Ssfr (not shown).

[0120] Moreover, the control unit 6 also performs the following calculations for the replenishing fluid flow rate for use in the first feedback control.

[0121] (Equation 8)

[0122] Replenishing fluid correction amount Sc = circulating set replenishing fluid flow rate Ssfr - target replenishing fluid flow rate Stf

[0123] According to this Equation 8, the replenishing fluid correction amount Sc is calculated as follows.

[0124] -10 (mL / min) = 90 (mL / min) - 100 (mL / min)

[0125] After calculating the circulating set replenishing fluid flow rate Ssfr in this way, the control unit 6 further performs feedback control on the second flow throttling unit MV2 at the start time of the next cycle.

[0126] Using the following Equation 9, the replenishing fluid pressure loss SL generated when the dialysate flows through the second flow throttling unit MV2 is calculated.

[0127] (Equation 9)

[0128] Replenishing fluid pressure loss SL = connection part pressure PG2 - blood pressure PV + η

[0129] Here, the connection part pressure PG2 represents the pressure value measured by the connection part pressure sensor PG2 provided in the above-mentioned dialysate supply passage 14, and the blood pressure PV represents the pressure value measured by the venous side pressure sensor PV provided in the venous side passage 8 of the above-mentioned blood circuit 3.

[0130] In addition, η in the above formula (9) is a value including the pressure loss of other elements (such as the on-off valve V10 and the connection port 19) added to the path from the second flow throttle unit MV2 to the venous side pressure sensor PV, the weight of the dialysate in the pipe constituting this section, and the like.

[0131] In addition, in the second feedback control, regarding the connection part pressure PG2 and the blood pressure PV, the pressure values at the end of one cycle are used. Therefore, the replenishing fluid pressure loss SL calculated using the above formula (9) becomes the cycle replenishing fluid pressure loss SLr calculated for each cycle.

[0132] After obtaining the cycle replenishing fluid pressure loss SLr in this way, next, the following formula (10) is used to calculate the replenishing fluid pressure loss coefficient ζS.

[0133] [Formula (10)]

[0134]

[0135] Here, the replenishing fluid flow rate in the above formula (10) can be calculated by dividing the actually calculated cycle replenishing fluid flow rate Safr by the cross-sectional area of the pipe constituting the dialysate circuit 4.

[0136] In the second feedback control, as the connection part pressure PG2 and the blood pressure PV, the pressure values at the end of one cycle are used. Therefore, the replenishing fluid pressure loss coefficient ζS calculated using the above formula (10) becomes the cycle replenishing fluid pressure loss coefficient ζSr calculated for each cycle.

[0137] Moreover, the second command voltage V2 for controlling the second flow throttle unit MV2 can be calculated by substituting the above cycle replenishing fluid pressure loss coefficient ζSr into the following formula (11).

[0138] (Formula (11))

[0139] Second command voltage V1 = -δ + ln(replenishing fluid pressure loss coefficient ζS) + ε

[0140] Here, δ and ε in formula (11) are constants.

[0141] In the second feedback control, at the end of one cycle, the second flow throttle unit MV2 is controlled. The second command voltage V2 calculated using the above formula (11) becomes the cycle second command voltage V2r calculated for each cycle.

[0142] After calculating the cycle second command voltage V2r in this way, at the start time of the next cycle, the control unit 6 applies the above cycle second command voltage V2r to the second flow throttle unit MV2 in the same way as the control of the first flow throttle unit MV1, and controls the opening degree of the second flow throttle unit MV2 (Figure 2 (black square).

[0143] Thus, in the above second feedback control, based on the dialysate flow rate and the replacement fluid flow rate during a relatively long time such as one cycle, the cycle-set dialysate flow rate Dsfr and the cycle-set replacement fluid flow rate Ssfr are updated. Accordingly, the opening degrees of the first and second flow throttle units MV1 and MV2 are updated.

[0144] Here, Figure 2 is used to illustrate the operation in the case where only the second feedback control is performed.

[0145] First, in the first cycle, due to the reasons as described above, that is, the deviation such as the pressure loss caused by the components, etc., the actual cycle actual replacement fluid flow rate Safr becomes larger than the target replacement fluid flow rate Stf.

[0146] Therefore, the control unit 6 performs the above second feedback control, sets the corrected cycle-set replacement fluid flow rate Ssfr in the second cycle, and sets the opening degree of the second flow throttle unit MV2.

[0147] In Figure 2 , the opening degree of the second flow throttle unit MV2 is controlled to throttle more than the opening degree in the first cycle, thereby performing control to make the actual replacement fluid flow rate Saf in the second cycle smaller than the actual replacement fluid flow rate Saf in the first cycle.

[0148] Moreover, by repeating the above second feedback control for each cycle, the cycle actual replacement fluid flow rate Safr that has deviated at the start time of the dialysis treatment can be converged to the target replacement fluid flow rate Stf.

[0149] However, only through the second feedback control, there is a problem that it cannot quickly converge to the target replacement fluid Stf when a sudden pressure change such as a kink occurs in the blood circuit 3.

[0150] Here, as an example, the case where a kink occurs on the upstream side of the connection portion between the blood circuit 3 and the replacement fluid passage 5 in the second cycle is described.

[0151] When a kink occurs on the upstream side of the connection portion, a negative pressure is relatively generated on the downstream side of the connection portion in the blood circuit 3, and the pressure difference between the dialysate circuit 4 and the blood circuit 3 increases, so a large amount of replacement fluid flows in from the replacement fluid passage 5.

[0152] In the second feedback control, the opening degree of the second flow throttle unit MV2 set at the start time of the second cycle is maintained, so a large amount of dialysate flows from the replacement fluid passage 5 into the blood circuit 3.

[0153] After that, if the kink is eliminated, the actual fluid infusion volume Saf decreases, but the actual fluid infusion flow rate Safr in the second cycle becomes greater than the target fluid infusion flow rate Stf.

[0154] Then, although the control unit 6 sets the corrected cyclic set fluid infusion flow rate Ssfr in the third cycle, since its value is less than the target fluid infusion flow rate Stf, the opening degree of the second flow throttle unit MV2 in the third cycle is further throttled compared to that in the second cycle.

[0155] As a result, the actual fluid infusion flow rate Safr in the third cycle becomes a value lower than the target fluid infusion flow rate Stf and deviates. In this case, the control unit 6 sets the opening degree of the second flow throttle unit MV2 in the fourth cycle to be larger.

[0156] Then, this time the actual fluid infusion flow rate Safr in the fourth cycle will become greater than the target fluid infusion flow rate Stf. In this way, even if the control unit 6 wants to make the actual fluid infusion flow rate Safr converge to the target fluid infusion flow rate Stf through the second feedback control, it takes a long time until the cyclic set fluid infusion flow rate Ssfr converges to the target fluid infusion flow rate Stf, and the fluid infusion flow rate becomes unstable.

[0157] In contrast, in the first feedback control, by updating the opening degrees of the first and second flow throttle units MV1 and MV2 several times during one cycle, for example, in the case of a sudden pressure change in the blood circuit 3 such as a kink, the fluid infusion flow rate is quickly stabilized.

[0158] In Figure 3 , in the first feedback control, the control unit 6 updates the opening degree of the first flow throttle unit MV1 every 2 seconds. The opening degree at this time is the opening degree calculated based on the corrected cyclic set dialysate flow rate Dsfr (the target dialysate flow rate Dtf in the case of the first cycle) calculated in the above second feedback control in this cycle.

[0159] In addition, regarding the update interval, it is not limited to 2 seconds and can be arbitrarily set as long as it can be performed multiple times in one cycle.

[0160] As will be described in detail below, the control unit 6 performs feedback control on the opening degree of the first flow throttle unit MV1 after 2 seconds as described below.

[0161] First, using the following formula 12, the dialysate pressure loss DL generated when the dialysate flows through the first flow throttle unit MV1 is calculated.

[0162] (Formula 12)

[0163] Dialysate pressure loss DL = connection part pressure PG2 - dialysate pressure PG3 - γ

[0164] Among them, the connection part pressure PG2 and the dialysate pressure PG3 are pressure values measured per unit time, and the dialysate pressure loss DL thus obtained becomes the dialysate pressure loss DLu per unit time.

[0165] After obtaining the dialysate pressure loss DLu per unit time in this way, the following formula 13 is then used to calculate the dialysate pressure loss coefficient ζD.

[0166] [Formula 13]

[0167]

[0168] Here, the corrected cyclic set dialysate flow rate Dsfr calculated in the above second feedback control in this cycle is used to calculate the dialysate flow velocity in the above formula 13. The reason is that in this embodiment, the dialysate flow rate is calculated for each cycle using the above flowmeter 18, so the flow rate per unit time cannot be measured.

[0169] Here, the dialysate pressure loss coefficient ζD is calculated based on the connection part pressure PG2, the dialysate pressure PG3 per unit time, and the corrected cyclic set dialysate flow rate Dsfr in this cycle. The dialysate pressure loss coefficient ζD thus obtained is set as the dialysate pressure loss coefficient ζDu per unit time.

[0170] Moreover, the first command voltage V1 for controlling the above first flow throttling unit MV1 can be calculated by substituting the above dialysate pressure loss coefficient ζDu per unit time into the following formula 14.

[0171] (Formula 14)

[0172] The first command voltage V1u = -α + ln(dialysate pressure loss coefficient ζD) + β

[0173] As described above, the dialysate pressure loss coefficient ζDu per unit time is calculated per unit time, so the first command voltage V1 calculated using the above formula 14 becomes the first command voltage V1u per unit time calculated per unit time.

[0174] In this way, the control unit 6 calculates the first command voltage V1u per unit time per unit time, and applies the first command voltage V1u per unit time to the above first flow throttling unit MV1, thereby controlling the opening degree of the first flow throttling unit MV1 per unit time (omitted in Figure 2 )

[0175] Similar to the second feedback control, in the first feedback control, in order to correct the replenishment flow rate, the second command voltage V2u per unit time for controlling the above second flow throttling unit MV2 is also calculated.

[0176] In this embodiment, the control unit 6 updates the opening degree of the second flow throttle unit MV2 every 1 second, and this opening degree is calculated according to the corrected cyclic set replenishing liquid flow rate Ssfr (target replenishing liquid flow rate Stf in the case of the first cycle) calculated in the second feedback control in this cycle.

[0177] In addition, regarding the update interval, it is not limited to 1 second, and it can be arbitrarily set as long as it can be performed multiple times within one cycle.

[0178] As described in detail below, the control unit 6 performs feedback control on the opening degree of the second flow throttle unit MV2 after 1 second as described below.

[0179] First, using the following formula 15, the replenishing liquid pressure loss SL generated when the dialysate flows through the second flow throttle unit MV2 is calculated.

[0180] (Formula 15)

[0181] Replenishing liquid pressure loss SL = connection part pressure PG2 - blood pressure PV - η

[0182] Here, the connection part pressure PG2 and the blood pressure PV become the pressure values per 1 second, and the replenishing liquid pressure loss SL calculated using the above formula 9 becomes the unit time replenishing liquid pressure loss SLu calculated per unit time.

[0183] After obtaining the unit time replenishing liquid pressure loss SLu in this way, then the following formula 16 is used to calculate the replenishing liquid pressure loss coefficient ζS.

[0184] [Formula 16]

[0185]

[0186] Here, the corrected cyclic set replenishing liquid flow rate Ssfr calculated in the second feedback control in this cycle is used to calculate the replenishing liquid flow velocity in the above formula 16. The reason is that as described above, the actual replenishing liquid flow rate is calculated for each cycle, so the flow rate per unit time cannot be measured.

[0187] Here, the dialysate pressure loss coefficient ζD is calculated through the connection part pressure PG2, blood pressure PV, and unit time set replenishing liquid flow rate Ssfu per unit time, so the replenishing liquid pressure loss coefficient ζS obtained in this way becomes the unit time replenishing liquid pressure loss coefficient ζSu.

[0188] Moreover, the second command voltage V2 for controlling the second flow throttle unit MV2 can be calculated by substituting the above unit time replenishing liquid pressure loss coefficient ζSu into the following formula 17.

[0189] (Formula 17)

[0190] The second command voltage V1 = -δ + ln(fluid infusion pressure loss coefficient ζS) + ε

[0191] In the first feedback control, the second flow throttling unit MV2 is controlled every 1 second, and the second command voltage V2 calculated using the above formula 17 becomes the second command voltage V2u per unit time calculated per unit time.

[0192] After calculating the second command voltage V2u per unit time in this way, the control unit 6 applies the second command voltage V2u per unit time to the second flow throttling unit MV2, and controls the opening degree of the second flow throttling unit MV2 per unit time ( Figure 3 white diamond).

[0193] Explanation Figure 3 The case where the first feedback control and the second feedback control are performed is shown. Here, it is explained that, similar to the case of Figure 2 , in the case where a kink occurs on the upstream side of the connection portion between the blood circuit 3 and the fluid infusion passage 5 in the middle of the second cycle, the feedback control is performed.

[0194] Similar to Figure 2 , the pressure at the connection portion between the blood circuit 3 and the fluid infusion passage 5 drops sharply, and the actual fluid infusion flow rate temporarily increases immediately after the kink occurs. However, the control unit 6 performs the first feedback control to change the opening degree of the second flow throttling unit MV2 per unit time, thereby quickly suppressing the increase in the actual fluid infusion flow rate.

[0195] As a result, the actual fluid infusion flow rate in the second cycle can be made close to the cycle-set fluid infusion flow rate Ssfr of the second cycle corrected by the above second feedback control.

[0196] Thus, compared with the case where only the second feedback control is performed as shown in Figure 2 , the cycle-set fluid infusion flow rate Ssfr in the third cycle converges to the target fluid infusion flow rate Stf.

[0197] That is, by performing the first feedback control together with the second feedback control, even when a sudden change occurs in the differential pressure between the blood circuit 3 and the dialysate circuit 4, the fluid infusion flow rate can be quickly stabilized.

[0198] In addition, in the above embodiment, the first feedback control and the second feedback control are performed, but the second feedback control may be omitted, and the feedback may be performed only by the first feedback control.

[0199] In this case, instead of setting the loop-set replenishment flow rate Ssfr for each loop, the control unit 6 may control the first and second flow throttle units MV1 and MV2 so as to converge to a preset target replenishment flow rate Stf.

[0200] In addition, in the above embodiment, the control unit uses the above formula for the first feedback control or the second feedback control. However, in addition to this, for each replenishment flow rate set as the target (target replenishment flow rate Stf or loop-set replenishment flow rate Ssfr), the relationship between the differential pressure between the connection part pressure PG2 and the blood pressure PV and the opening degrees (command voltages) of the first and second flow throttle units MV1 and MV2 at this time may be measured in advance and stored in a required table.

[0201] In this case, when the control unit 6 measures the connection part pressure PG2 and the blood pressure PV during dialysis treatment, the command voltage corresponding to the target dialysate flow rate Dtf or the loop-set dialysate flow rate Dsfr at this time is read from the above table, and the opening degrees of the first flow throttle unit MV1 and the second flow throttle unit MV2 may be controlled.

[0202] (Symbol Explanation)

[0203] 1: Hemodialysis device; 2: Dialyzer; 3: Blood circuit; 4: Dialysate circuit; 5: Replenishment passage; 6: Control unit; 7: Arterial side passage; 8: Venous side passage; 14: Dialysate supply passage; 15: Dialysate recovery passage; MV1: First flow throttle unit; MV2: Second flow throttle unit; PV: Venous side pressure sensor (blood circuit pressure measurement unit); PG2: Connection part pressure sensor (connection part pressure measurement unit); Dtf: Target dialysate flow rate; Stf: Target replenishment flow rate; Safr: Circulation actual replenishment flow rate; Ssfr: Loop-set replenishment flow rate; Sc: Replenishment correction amount; SLr: Circulation replenishment pressure loss; ζSr: Circulation replenishment pressure loss coefficient; Ssfu: Unit time set replenishment flow rate; SLu: Unit time replenishment pressure loss; ζSu: Unit time replenishment pressure loss coefficient.

Claims

1. A hemodialysis device, characterized in that, it comprises: a dialyzer for performing hemodialysis; a chamber provided in the dialysate circuit and accommodating dialysate; a fresh dialysate supply passage connected to the supply chamber of the chamber and supplying fresh dialysate to the dialyzer; a used dialysate recovery passage connected to the recovery chamber of the chamber and recovering the used dialysate flowing through the dialyzer; a blood circuit for allowing blood to flow through the dialyzer; a fluid replenishment passage provided between the fresh dialysate supply passage and the blood circuit; a first flow restrictor unit provided on the downstream side of the connection portion of the fresh dialysate supply passage with the fluid replenishment passage; a second flow restrictor unit provided in the fluid replenishment passage; and a control unit for controlling the first flow restrictor unit and the second flow restrictor unit, by controlling the first flow restrictor unit and the second flow restrictor unit by the control unit, adjusting the fluid replenishment flow rate supplied to the blood circuit via the fluid replenishment passage, the hemodialysis device comprises: a connection portion pressure measurement unit for measuring the pressure at the connection portion of the fresh dialysate supply passage and the fluid replenishment passage; and a blood circuit pressure measurement unit for measuring the pressure of the blood circuit, during one cycle from the state where the supply chamber of the chamber is filled with fresh dialysate to the state where all the fresh dialysate in the supply chamber is discharged, the control unit performs feedback control for adjusting the second flow restrictor unit multiple times according to the set target fluid replenishment flow rate, the measured pressure of the connection portion pressure measurement unit, and the measured pressure of the blood circuit pressure measurement unit.

2. The hemodialysis device according to claim 1, characterized in that, in addition to performing the first feedback control multiple times during the one cycle, the control unit also sets the cycle set fluid replenishment flow rate for the next cycle, which is set as the target in the next cycle, according to the actual cycle fluid replenishment flow rate in this cycle and the cycle set fluid replenishment flow rate for this cycle, which is set as the target in this cycle, and performs the second feedback control for adjusting the first flow restrictor unit and the second flow restrictor unit according to the measured pressure of the connection portion pressure measurement unit and the measured pressure of the blood circuit pressure measurement unit at the end of this cycle.

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