(19)
(11)EP 2 019 296 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
18.01.2017 Bulletin 2017/03

(21)Application number: 07741511.5

(22)Date of filing:  12.04.2007
(51)Int. Cl.: 
G01G 3/14  (2006.01)
A61M 1/34  (2006.01)
G01G 21/16  (2006.01)
A61M 1/14  (2006.01)
G01G 17/04  (2006.01)
(86)International application number:
PCT/JP2007/058075
(87)International publication number:
WO 2007/119786 (25.10.2007 Gazette  2007/43)

(54)

WEIGHT SENSOR AND BALANCE CONTROLLER

GEWICHTSSENSOR UND BALANCESTEUERUNG

CAPTEUR DE POIDS ET REGULATEUR D'EQUILIBRE


(84)Designated Contracting States:
AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LI LT LU LV MC MT NL PL PT RO SE SI SK TR

(30)Priority: 14.04.2006 JP 2006112621

(43)Date of publication of application:
28.01.2009 Bulletin 2009/05

(73)Proprietor: JMS Co., Ltd.
Hiroshima-shi, Hiroshima 730-8652 (JP)

(72)Inventors:
  • FUJII, Junya
    Hiroshima-shi,Hiroshima 730-8652 (JP)
  • KAMITO, Shogo
    Hiroshima-shi, Hiroshima 730-8652 (JP)
  • ENDO, Toshiyuki
    Tajimi-shi, Gifu 507-0054 (JP)
  • SANSHO, Youichi
    Kitamoto-shi, Saitama 364-8585 (JP)

(74)Representative: Pautex Schneider, Nicole Véronique et al
Novagraaf International SA Chemin de l'Echo 3
1213 Onex
1213 Onex (CH)


(56)References cited: : 
DE-A1- 19 857 381
JP-A- 09 239 024
JP-A- 2006 105 734
JP-B2- 06 090 067
US-A- 4 558 756
GB-A- 2 182 156
JP-A- 2003 214 938
JP-A- 2006 105 734
US-A- 3 602 866
US-A- 4 712 567
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    Technical Field



    [0001] The present invention relates to a weight sensor that detects a weight of a substance, and a balance controller that balances among weights of plural substances.

    Background Art



    [0002] Conventionally, in order to purify blood of patients with renal function insufficiency, for example, medical treatments using Continuous Hemofiltration (CHF), Continuous Hemodiafiltration (CHDF), and/or the like have been performed. In the CHF, blood taken from a patient is provided to a blood purifier having a semipermeable membrane (hemofiltration membrance) for hemofiltration, and then filtered by the hemofiltration membrane to generate purified blood. The purified blood is returned to the patient body, and waste products (electrolytic substance such as urea and sodium chloride, for example) and solvent (water) resulting from the hemofiltration are discarded. In parallel, a predetermined replacement fluid is supplied to blood of the patient so as to supplement a decrease in solvent of the blood. The above processing is performed continually and slowly. In the CHF, waste products and solvent which are taken from blood in order to be discarded are called filtrate.

    [0003] On the other hand, the CHDF is a method of improving a capability of removing small molecules in the CHF. In the CHDF, dialysis as well as the CHF are performed. More specifically, in the CHDF, a blood purifier having a dialysis membrane in addition to a hemofiltration membrane is used. The blood purifier is provided also with dialysate. Waste products still included in the purified blood after hemofiltration are sent to the dialysate through the dialysis membrane, so that the waste products can be removed from the blood. Then, the blood purified by the hemofiltration and the dialysis is returned to the patient body and a replacement fluid is supplied to the blood of the patient. The above processing is performed continuously and slowly. In the CHDF, waste product and solvent which are taken from the blood during hemofiltration, and used dialysate are called filtrate.

    [0004] In the meanwhile, a sudden change in an amount of blood in a patient body causes rapid deterioration of patient's condition. In order to avoid such situations, it is necessary to keep a balance between (i) a flow rate of blood taken from the patient and (ii) a total flow rate of blood returned to the patient and replacement fluid supplied to the patient. The following explains blood purification systems using the CHDF that keep a balance between (i) a flow rate of blood taken from a patient and (ii) a total flow rate of blood returned to the patient and replacement fluid supplied to the patient. There are a first scheme, a second scheme (disclosed in Patent Reference 1, for example), and a third scheme as blood purification systems. The first scheme, the second scheme, and the third scheme of blood purification systems are sequentially explained below.

    [0005] Firstly, the first scheme of blood purification system is explained with reference to FIG. 1. FIG. 1 is a block diagram of the first scheme of blood purification system which keeps, within a predetermined range, a difference between (i) a total weight of dialysate and replacement fluid and (ii) a weight of filtrate. In the first scheme of blood purification system as shown in FIG. 1, a blood pump 6 sends blood taken from a patient A to a blood purifier 10 via an artery-side blood circuit 11. The blood purifier 10 has a hemofiltration membrane to remove water from the taken blood. A dialysate pump 7 sends dialysate contained in a dialysate container 3 to the blood purifier 10 via a dialysate supply channel 12. The blood purifier 10 removes water and waste products from the taken blood via the filtrate (dialysis) membrane. The blood purified by the blood purifier 10 is returned to the patient A via a vein-side blood circuit 13. A replacement fluid pump 8 mixes a replacement fluid contained in a replacement fluid container 4 into the vein-side blood circuit 13, thereby supplying the replacement fluid together with the purified blood into the patient A. A filtrate pump 9 sends, as filtrate, the used dialysate and the waste products which are taken from the blood by the blood purifier 10, from the blood purifier 10 to a filtrate container 5 via a filtrate discard channel 14. A dialysate/replacement fluid weight measuring device 91 measures a total weight of dialysate contained in the dialysate container 3 and replacement fluid contained in the replacement fluid container 4. A filtrate weight measuring device 92 measures a weight of filtrate contained in the filtrate container 5. A control unit 93 controls operations, such as the number of rotations, of the dialysate pump 7, the replacement fluid pump 8, and the filtrate pump 9, in order to keep, within a predetermined range, a difference between (i) the total weight of the dialysate and the replacement fluid measured by the dialysate/replacement fluid weight measuring device 91 and (ii) the weight of the filtrate measured by the filtrate weight measuring device 92. This achieves a balance between (i) a flow rate of blood taken from a patient and (ii) a total flow rate of blood returned to the patient and replacement fluid supplied to the patient.

    [0006] Secondly, the second scheme of blood purification system is explained with reference to FIG. 2. FIG. 2 is a block diagram of the second scheme of blood purification system, which calculates a flow rate of to-be-used dialysate, a flow rate of to-be-used replacement fluid, and a flow rate of to-be-discarded filtrate, using respective different weight measuring devices, and thereby keeps the flow rates to have predetermined values, respectively. The second scheme of blood purification system of FIG. 2 differs from the first scheme of blood purification system of FIG. 1 in the following. That is, in the second scheme of blood purification system, to-be-used dialysate is acquired and stored into a dialysate acquisition container 101, and an acquired-dialysate weight measuring device 102 measures a weight of the dialysate contained in the dialysate acquisition container 101. A control unit 107 calculates an amount of a temporal change (hereinafter, referred to also as a "temporal change amount") in the weight of the dialysate measured by the acquired-dialysate weight measuring device 102, and thereby calculates a flow rate of currently-using dialysate. Then, the control unit 107 controls operations, such as the number of rotations, of a dialysate pump 7 to keep the calculated flow rate of the dialysate to be a predetermined flow rate. Likewise, to-be-used replacement fluid is acquired and stored into a replacement fluid acquisition container 103, and an acquired-replacement-fluid weight measuring device 104 measures a weight of the replacement fluid contained in the replacement fluid acquisition container 103. The control unit 107 calculates a temporal change amount of the weight of the replacement fluid measured by the acquired-replacement-fluid weight measuring device 104, and thereby calculates a flow rate of currently-using replacement fluid. Then, the control unit 107 controls operations, such as the number of rotations, of a replacement fluid pump 8 to keep the calculates flow rate of the replacement fluid to be a predetermined flow rate. Filtrate to be discarded is acquired and stored into a filtrate acquisition container 105, and an acquired-filtrate weight measuring device 106 measures a weight of the filtrate contained in the filtrate acquisition container 105, The control unit 107 calculates a temporal change amount of the weight of the filtrate measured by the acquired-filtrate weight measuring device 106, and thereby calculates a flow rate of currently discarding filtrate. Then, the control unit 107 controls operations, such as the number of rotations, of a filtrate pump 9 to keep the calculated flow rate of the filtrate to be a predetermined flow rate. This achieves a balance between (i) a flow rate of blood taken from a patient and (ii) a total flow rate of blood returned to the patient and replacement fluid supplied to the patient.

    [0007] Finally, the third scheme of blood purification system is explained. As described above, the second scheme of blood purification system separately calculates a flow rate of to-be-used dialysate, a flow rate of to-be-used replacement fluid, and a flow rate of to-be-discarded filtrate, using respective different wight measuring devices, and thereby keeps the flow rates to have predetermined values, respectively. On the other hand, the third scheme of blood purification system calculates a flow rate of to-be-used dialysate, a flow rate of to-be-used replacement fluid, and a flow rate of to-be-discarded filtrate, using a single weight measuring device that is used by being sequentially delayed to measure respective liquids. As a result, flow rates of the respective liquids are kept to be predetermined values, respectively. This achieves a balance between (i) a flow rate of blood taken from a patient and (ii) a total flow rate of blood returned to the patient and replacement fluid supplied to the patient.

    [0008] Patent Reference 1: Japanese Unexamined Patent Application Publication No. 9-239024

    [0009] Also, document JP 2006 105734 describes a conventional sensor, that only detects torque, and comprising the features of the preamble of claim 1, i.e. a pillar, an arm having one end fixed to the pillar (via intermediate element) and the other end being free. This sensors further comprises n holders provided at n locations on a side surface of said arm along a longitudinal direction, each of which being configure to hold a substance, n being a natural number equal or greater than two and n torque sensors, provided on the arm in association with n sums, respectively, each of which is specifically configured to detect a torque of said arm corresponding to a corresponding sum among the n sum.

    Disclosure of Invention


    Problems that Invention is to Solve



    [0010] However, the above-explained three schemes of blood purification system have their problems.

    [0011] As explained above, the first scheme of blood purification system keeps, within a predetermined range, a difference between (i) a total weight of dialysate and replacement fluid and (ii) a weight of filtrate, thereby achieving a balance between (i) a flow rate of blood taken from a patient and (ii) a total flow rate of blood returned to the patient and replacement fluid supplied to the patient. However, it is impossible to completely and accurately measure weights and flow rates of to-be-used dialysate and to-be-used replacement fluid. Thereby, in the case of medical treatments using the CHDF, when dialysate or replacement fluid is to be supplied in the middle of the treatment, it is not sure how much of the liquid should be supplied. It is not clear either how much of the liquid should be prepared for a next treatment. As a result, large excess amounts of dialysate and replacement fluid should be prepared in order not to be run out during medical treatments.

    [0012] The second and third schemes of blood purification system calculate a total flow rate of to-be-used dialysate and to-be-used replacement fluid, and also a flow rate of to-be-discarded filtrate, as described above. However, there is an error between each calculated flow rate and an actual flow rate. Therefore, even if the calculated flow rate of each liquid is kept to have a corresponding predetermined value, there is a high possibility of failing to control for balancing between (i) a flow rate of blood taken from a patient and (ii) a total flow rate of blood returned to the patient and replacement fluid supplied to the patient. The failure in balance results in deterioration of patient's condition.

    [0013] As explained above, the conventional devices and methods cannot simultaneously achieve both of (i) balance among weights of plural substances and (ii) detection of the respective weights of the substances.

    [0014] Thus, the present invention overcomes the conventional problems. It is an object of the present invention to provide a weight sensor that detects respective correct weights of plural substances, and a balance controller that achieves a balance among the weights of the substances with a high accuracy.

    Means to Solve the Problems



    [0015] In accordance with an aspect of the present invention for achieving the object, there is provided a weight sensor as defined in claims 1 to 13.

    [0016] For example, when a part of substance held by the second holder counted from the pillar is transferred to a holder proximate to the pillar via a predetermined part, the transfer does not affect a total weight (sum of weights) of substances held by holders ranging from the holder proximate to the pillar to a holder proximate to the free end of the arm. What the weight sensor according to the present invention calculates is the total weight (sum of weights). Therefore, by monitoring the total weight (sum of weights) calculated by the weight sensor according to the present invention, it is possible to balance between (i) an amount of decrease in the substance held by the second holder counted from the pillar and (ii) an amount of increase or decrease in the substance held by the holder proximate to the pillar. That is, the weight sensor according to the present invention is used to balance among weights of a plurality of substances.

    [0017] As another example, if the number of the holders is two, the weight sensor according to the present invention detects a weight of the substance held by the holder proximate to the free end of the arm, and also detects a sum of weights of substances held by the two holders. The sum is subtracted by the weight of the substance held by the holder proximate to the free end of the arm, thereby calculating a weight of the substance held by the holder proximate to the pillar. That is, the weight sensor according to the present invention is used to calculate a weight of each of the plurality of substances.

    [0018] The weight calculation unit may be configured to calculate the weights of the substances held by the n holders, respectively, based on results of the detection of the n strain value sensors.

    [0019] The weight sensor may further include a display unit configured to display results of the calculation of the weight calculation unit.

    [0020] The arm may be a member including n bar-shaped members connected in series at each end, each of the n bar-shaped members may have a hole penetrating in a direction perpendicular to the longitudinal direction of the arm without penetrating the side surface, and the n holders may be provided on the n bar-shaped members, respectively.

    [0021] A shape of the hole in a cross section may be symmetry with respect to a bisector of a line segment perpendicular to the longitudinal direction of the arm in the cross section of the hole, and also symmetry with respect to a bisector of a line segment along the longitudinal direction of the arm in the cross section of the hole.

    [0022] A size of each of a closer end and a farther end of the cross section of the hole may be larger than a size of a part of the cross section of the hole between the closer end and the farther end, the closer end being closer to the pillar and an farther end being farther from the pillar.

    [0023] The n strain value sensors may be Roberval strain value sensors provided on the n bar-shaped members, respectively.

    [0024] The arm may have holes each of which penetrates in a direction perpendicular to the longitudinal direction of the arm without penetrating the side surface, the holes being provided between the pillar and the holder proximate to the pillar and between two neighboring holders, respectively.

    [0025] A shape of each of the holes in a cross section may be symmetry with respect to a bisector of a line segment perpendicular to the longitudinal direction of the arm in the cross section of the hole, and also symmetry with respect to a bisector of a line segment along the longitudinal direction of the arm in the cross section of the hole.

    [0026] A size of each of a closer end and a farther end of the cross section of the hole may be larger than a size of a part of the cross section of the hole between the closer end and the farther end, the closer end being closer to the pillar and an farther end being farther from the pillar.

    [0027] The n strain value sensors may be Roberval strain value sensors, and the n strain value sensors are provided between the pillar and the holder proximate to the pillar and between the two neighbor holders, respectively and separately.

    [0028] The weight sensor may further include an increased/decreased amount calculation unit configured to calculate an amount of increase or decrease in a weight of the substance held by each of the n holders from an initial weight of the substance, based on results of the calculation of the n weight calculation units.

    [0029] The weight sensor may further include a temporal change amount calculation unit configured to calculate an amount of a temporal change in a weight of the substance held by each of the n holders, based on results of the calculation of the n weight calculation units.

    [0030] In accordance with another aspect of the present invention, there is provided a balance controller according to claim 14.

    [0031] The number of the holders may be three, a first holder in the holders may hold filtrate, a second holder in the holders may hold replacement fluid, and a third holder in the holders may hold dialysate, and the control unit may be configured to keep a sum of a weight of the filtrate, a weight of the replacement fluid, and a weight of the dialysate within a predetermined range, so as to balance between an amount of temporal increase in the filtrate and an amount of temporal decrease in the replacement fluid and the dialysate.

    [0032] The number of the n holders may be two, a first holder in the holders may hold filtrate, and a second holder in the holders may hold replacement fluid, and the control unit may be configured to keep a sum of a weigh of the filtrate and a weight of the replacement fluid within a predetermined range, so as to balance between an amount of temporal increase in the filtrate and an amount of temporal decrease in the replacement fluid.

    Effects of the Invention



    [0033] Thus, the present invention can provide a weight sensor that detects respective weights of plural substances, and a balance controller that achieves a balance among the weights of the plural substances.

    Brief Description of Drawings



    [0034] 

    [FIG. 1] FIG. 1 is a block diagram of a conventional blood purification system.

    [FIG. 2] FIG. 2 is a block diagram of another conventional blood purification system.

    [FIG. 3] FIG. 3 is a block diagram of a blood purification system according to a first example not forming part of the present invention.

    [FIG. 4] FIG. 4 is a block diagram of a weight sensor 1 according to the first example.

    [FIG. 5A] FIG. 5A is a graph plotting increase in a weight of discarded filtrate as time passes.

    [FIG. 5B] FIG. 5B is a graph plotting decrease in a total weight of used replacement fluid and used dialysate as time passes.

    [FIG. 6] FIG. 6 is a diagram showing one example of a screen on which a display 33 of the weight sensor 1 displays calculation results, according to first example.

    [FIG. 7] FIG. 7 is a flowchart of processing performed by the blood purification system according to first example.

    [FIG. 8] FIG. 8 is a diagram showing a part of a structure of a weight sensor 1 according to a first modification of the first example.

    [FIG. 9] FIG. 9 is a diagram showing a part of a structure of a weight sensor 1 according to an embodiment of the present invention.

    [FIG. 10] FIG. 10 is a diagram showing a part of a structure of a weight sensor 1 according to a second example.


    Numerical References



    [0035] 
    1
    weight sensor
    2
    balance controller
    3
    dialysate container
    4
    replacement fluid container
    5
    filtrate container
    6
    blood pump
    7
    dialysate pump
    8
    replacement fluid pump
    9
    filtrate pump
    10
    blood purifier
    11
    artery-side blood circuit
    12
    dialysate supply channel
    13
    vein-side blood circuit
    14
    filtrate discard channel
    21
    base
    22
    pillar
    23
    arm
    23a
    first square bar
    23b
    second square bar
    23c
    third square bar
    24
    filtrate holder
    25
    replacement fluid holder
    26
    dialysate holder
    27
    first strain value sensor
    28
    second strain value sensor
    29
    third strain value sensor
    30
    weight calculation unit
    31
    increased/decreased amount calculation unit
    32
    temporal change amount calculation unit
    33
    display unit
    41
    obtainment unit
    42
    control unit

    Best Mode for Carrying Out the Invention



    [0036] The following describes examples and the preferred embodiments according to the present invention with reference to the drawings.

    (First example)



    [0037] Firstly, a structure of a blood purification system according to the first example is described with reference to FIGS. 3 to 6.

    [0038] FIG. 3 is a block diagram of the blood purification system according to the first example. The blood purification system according to the first example is used, for example, when a medical treatment using the CHDF is applied to a patient A having a renal function insufficiency to purify his/her blood. This blood purification system balances between (i) a total flow rate of dialysate and replacement fluid that are currently used in the treatment and (ii) a flow rate of filtrate that is currently discarded, and also calculates and displays an amount of temporal change (namely, a flow rate) in each of the dialysate, the replacement fluid, and the filtrate. As shown in FIG. 3, the blood purification system according to the first example includes a weight sensor 1, a balance controller 2, a dialysate container 3, a replacement fluid container 4, a filtrate container 5, a blood pump 6, a dialysate pump 7, a replacement fluid pump 8, a filtrate pump 9, a blood purifier 10, an artery-side blood circuit 11, a dialysate supply channel 12, a vein-side blood circuit 13, and a filtrate discard channel 14.

    [0039] The weight sensor 1 is used to balance between (i) a total flow rate of using dialysate and using replacement fluid and (ii) a flow rate of discarding filtrate. The weight sensor 1 detects a weight, a flow rate that is a temporal change amount of the weight, and the like regarding each of dialysate, replacement fluid, and filtrate. Then, the weight sensor 1 displays the detected results. More detailed structure of the weight sensor 1 is described later with reference to FIG. 4. Based on the results detected by the weight sensor 1, the balance controller 2 controls operations of the dialysate pump 7, the replacement fluid pump 8, and the filtrate pump 9 to balance between (i) a total flow rate of using dialysate and using replacement fluid and (ii) a flow rate of discarding filtrate. The balance controller 2 includes: an obtainment unit 41 that obtains the results detected by the weight sensor 1; and a control unit 42 that controls operations of the dialysate pump 7, the replacement fluid pump 8, and the filtrate pump 9.

    [0040] The dialysate container 3 is a container in which dialysate to be used is contained. The replacement fluid container 4 is a container in which replacement fluid to be used is contained. The filtrate container 5 is a container in which filtrate to be discarded is contained. Each of the dialysate container 3, the replacement fluid container 4, and the filtrate container 5 has a handle on the top of the container. Using the above-mentioned handle, the dialysate container 3 is held by a dialysate holder 26 in the weight sensor 1. Likewise, using respective handles, the replacement fluid container 4 and the filtrate container 5 are held by a replacement fluid holder 25 and a filtrate holder 24 in the weight sensor 1, respectively.

    [0041] The blood pump 6 sends blood taken from the patient A to the blood purifier 10. The dialysate pump 7 sends the dialysate contained in the dialysate container 3 to the blood purifier 10. The replacement fluid pump 8 sends the replacement fluid contained in the replacement fluid container 4 to the vein-side blood circuit 13, thereby mixing the replacement fluid into blood purified by the blood purifier 10. The filtrate pump 9 sends filtrate generated by hemofiltration and dialysis (blood purification) of the blood purifier 10, into the filtrate container 5.

    [0042] The blood purifier 10 has a hemofiltration membrane and a dialysis membrane therein. The blood purifier 10 performs hemofiltration on blood taken from the patient A using the hemofiltration membrane, and also performs dialysis on the blood, using the dialysis membrane and dialysate from the dialysate container 3. In short, the blood purifier 10 purifies blood taken from the patient A. The artery-side blood circuit 11 is a traveling path of blood from the patient A to the blood purifier 10. The dialysate supply channel 12 is a traveling path of dialysate from the dialysate container 3 to the blood purifier 10. The vein-side blood circuit 13 is a traveling path of blood purified by the blood purifier 10 back to the patient A. The filtrate discard channel 14 is a traveling path of filtrate from the blood purifier 10 to the filtrate container 5. Each of the artery-side blood circuit 11, the dialysate supply channel 12, the vein-side blood circuit 13, and the filtrate discard channel 14 is a tube made of a predetermined synthetic resin.

    [0043] FIG. 4 is a diagram showing a structure of the weight sensor 1 according to the first example. The weight sensor 1 according to the first example is, as described previously, used to balance between (i) a total flow rate of using dialysate and using replacement fluid and (ii) a flow rate of discarding filtrate. The weight sensor 1 detects a weight, a flow rate that is a temporal change amount, and the like regarding each of dialysate, replacement fluid, and filtrate. Then, the weight sensor 1 displays the detection results. As shown in FIG. 4, the weight sensor 1 includes a base 21, a pillar 22, an arm 23, a filtrate holder 24, a replacement fluid holder 25, a dialysate holder 26, a first strain value sensor 27, a second strain value sensor 28, a third strain value sensor 29, a weight calculation unit 30, an increased/decreased amount calculation unit 31, a temporal change amount calculation unit 32, and a display unit 33. The weight sensor 1 also includes, as shown in FIG. 4, a balance controller 2, a dialysate container 3, a replacement fluid container 4, and a filtrate container 5.

    [0044] The base 21 is, for example, a flat plate made of aluminum. The pillar 22 is, for example, a bar-shaped member made of aluminum, and is fixed on the base 21 in perpendicular to the base 21. The arm 23 is a square bar having one end fixed to the pillar 22 and the other end that is a free end, so that the arm 23 is perpendicular to the pillar 22, in other words, in parallel to the base 21, namely, horizontally. As shown in FIG. 4, the arm 23 is a member comprised of the first square bar 23a, the second square bar 23b, and the third square bar 23c which are connected in series. In more detail, one end of the first square bar 23a is connected in series with one end of the second square bar 23b, and the other end of the second square bar 23b is connected in series with one end of the third square bar 23c. The other end of the first square bar 23a is fixed to the pillar 22. The first square bar 23a, the second square bar 23b, and the third square bar 23c are, for example, square bars made of aluminum. As shown in FIG. 4, each of the first square bar 23a, the second square bar 23b, and the third square bar 23c has a through-hole penetrating horizontally and in perpendicular to a longitudinal direction of the arm 23. A cross section of the through-hole is bone-shaped. More specifically, a shape of the through-hole in a cross section is symmetry with respect to a bisector of a vertical line segment of the cross section of the through-hole, and also symmetry with respect to a bisector of a line segment along the longitudinal direction of the arm 23 in the cross section of the through-hole. Here, a size of each of an end closer to the pillar 22 and the other end closer to the free end in the cross section of the through-hole is larger than a size of a central part of the cross section of the through-hole between the ends.

    [0045] The filtrate holder 24 is a member for holding the filtrate container 5, and provided on a surface of the first square bar 23a facing the base 21. The filtrate holder 24 is located between the through-hole of the first square bar 23a and the free end of the arm 23. The replacement fluid holder 25 is a member for holding the replacement fluid container 4, and provided on a surface of the second square bar 23b facing the base 21. The replacement fluid holder 25 is located between the through-hole of the second square bar 23b and the free end of the arm 23. The dialysate holder 26 is a member for holding the dialysate container 3, and provided on a surface of the third square bar 23c facing the base 21. The dialysate holder 26 is located between the through-hole of the third square bar 23c and the free end of the arm 23.

    [0046] The first strain value sensor 27 is a Roberval strain value sensor that is provided on the surface of the first square bar 23a facing the base 21. The first strain value sensor 27 is located between the through-hole of the first square bar 23a and the pillar 22. The first strain value sensor 27 detects an amount of strain (hereinafter, referred to as a "strain value") of the first square bar 23a, which corresponds to a sum (first sum) of: a weight of filtrate in the filtrate container 5 held by the filtrate holder 24; a weight of replacement fluid in the replacement fluid container 4 held by the replacement fluid holder 25; and a weight of dialysate in the dialysate container 3 held by the dialysate holder 26. The second strain value sensor 28 is a Roberval strain value sensor that is provided on the surface of the second square bar 23b facing the base 21. The second strain value sensor 28 is located between the through-hole of the second square bar 23b and the pillar 22. The second strain value sensor 28 detects a strain value of the second square bar 23b, which corresponds to a sum (second sum) of: the weight of the replacement fluid in the replacement fluid container 4 held by the replacement fluid holder 25; and the weight of the dialysate in the dialysate container 3 held by the dialysate holder 26. The third strain value sensor 29 is a Roberval strain value sensor that is provided on the surface of the third square bar 23c facing the base 21. The third strain value sensor 29 is located between the through-hole of the third square bar 23c and the pillar 22. The third strain value sensor 29 detects a strain value of the third square bar 23c, which corresponds to a sum (third sum) that is the weight of the dialysate in the dialysate container 3 held by the dialysate holder 26.

    [0047] The weight calculation unit 30 calculates a sum (the first sum) of: the weight of the filtrate in the filtrate container 5; the weight of the replacement fluid in the replacement fluid container 4; and the weight of the dialysate in the dialysate container 3, using the result detected by the first strain value sensor 27 and a relationship between the detected strain value and the weights. The weight calculation unit 30 also calculates a sum (the second sum) of: the weight of the replacement fluid in the replacement fluid container 4; and the weight of the dialysate in the dialysate container 3, using the result detected by the second strain value sensor 28 and a relationship between the detected strain value and the weights. The weight calculation unit 30 further calculates a sum (the third sum) that is the weight of the dialysate in the dialysate container 3, using the result detected by the third strain value sensor 29 and a relationship between the detected strain value and the weight. In addition, the weight calculation unit 30 calculates the weight of the filtrate in the filtrate contained 5 by subtracting the second sum from the first sum, and the weight of the replacement fluid in the replacement fluid container 4 by subtracting the third sum from the second sum.

    [0048] The increased/decreased amount calculation unit 31 calculates: an amount of increase in a weight of the filtrate in the filtrate container 5 calculated by the weight calculation unit 30 from an initial weight of the filtrate; an amount of decrease in a weight of the replacement fluid in the replacement fluid container 4 calculated by the weight calculation unit 30 from an initial weight of the replacement fluid; and an amount of decrease in a weight of the dialysate in the dialysate container 3 calculated by the weight calculation unit 30 from an initial weight of the dialysate. In other words, the increased/decreased amount calculation unit 31 calculates: a weight of filtrate which has been discarded; a weight of replacement fluid which has been used; and a weight of dialysate which has been used.

    [0049] Based on the weight of the filtrate in the filtrate container 5, the weight of the replacement fluid in the replacement fluid container 4, and the weight of the dialysate in the dialysate container 3 which have been calculated by the weight calculation unit 30, the temporal change amount calculation unit 32 calculates: a flow rate of the filtrate contained in the filtrate container 5; a flow rate of the replacement fluid contained in the replacement fluid container 4; and a flow rate of the dialysate contained in the dialysate container 3. Here, FIGS. 5A and 5B show how (A) a weight of discarded filtrate and (B) a total weight of used replacement fluid and used dialysate change as time passes, respectively. FIG. 5A is a graph plotting an increase of a weigh of discarded filtrate as time passes. FIG. 5B is a graph plotting a decrease of a total weight of used replacement fluid and used dialysate as time passes. A weigh of discarded filtrate is increased as time passes as shown in FIG. 5A, and a total weight of used replacement fluid and used dialysate is decreased as time passes as shown in FIG. 5B. Based on the weight of the filtrate in the filtrate container 5, the temporal change amount calculation unit 32 calculates a flow rate of the filtrate contained in the filtrate container 5 which is a temporal amount of increase in a weight of the filtrate in the filtrate container 5. Likewise, based on the weight of the replacement fluid in the replacement fluid container 4, the temporal change amount calculation unit 32 calculates a flow rate of the replacement fluid in the replacement fluid container 4 which is a temporal amount of decrease in a weight of the replacement fluid in the replacement fluid container 4. Also, based on the weight of the dialysate in the dialysate container 3, the temporal change amount calculation unit 32 calculates a flow rate of the dialysate in the dialysate container 3 which is a temporal amount of decrease in a weight of the dialysate in the dialysate container 3.

    [0050] The display unit 33 displays the results calculated by the weight calculation unit 30, the increased/decreased amount calculation unit 31, and the temporal change amount calculation unit 32. More specifically, the display unit 33 displays: the weigh of the filtrate in the filtrate container 5; the weight of the replacement fluid in the replacement fluid container 4; the weight of the dialysate in the dialysate container 3; the weight of discarded filtrate; the weight of used replacement fluid; the weight of used dialysate; the flow rate of the filtrate in the filtrate container 5; the flow rate of the replacement fluid in the replacement fluid container 4; and the flow rate of the dialysate in the dialysate container 3. FIG. 6 is a diagram showing one example of a screen on which the display 33 displays the calculation results.

    [0051] Next, processing performed by the blood purification system according to the first example is described with reference to FIG. 7.

    [0052] FIG. 7 is a flowchart of the processing performed by the blood purification system according to first example.

    [0053] Firstly, in the case of medical treatments using the CHDF to purify blood of the patient A, a physician stores a predetermined amount of replacement fluid into the replacement fluid container 4, and then sets the replacement fluid container 4 to be held by the replacement fluid holder 25 using a handle provided on the top of the replacement fluid container 4. Furthermore, the physician stores a predetermined amount of dialysate into the dialysate container 3, and then sets the dialysate container 3 to be held by the dialysate holder 26 using a handle provided on the top of the dialysate container 3. Still further, the physician sets an empty filtrate container 5 to be held by the filtrate holder 24 using a handle provided on the top of the filtrate container 5. Then, the physician connects the artery-side blood circuit 11 and the vein-side blood circuit 13 with the patient A, and then turns switches of the blood pump 6, the dialysate pump 7, the replacement fluid pump 8, and the filtrate pump 9 to be ON, so that a flow rate of the dialysate, a flow rate of the replacement fluid, and a flow rate of the filtrate become respective predetermined flow rates.

    [0054] When the switches of the pumps are turned ON, operations of the blood pump 6, the dialysate pump 7, the replacement fluid pump 8, the filtrate pump 9 start (S1). In more detail, the blood pump 6 sends blood taken from the patient A to the blood purifier 10 via the artery-side blood circuit 11, and the dialysate pump 7 sends the dialysate contained in the dialysate container 3 to the blood purifier 10 via the dialysate supply channel 12. The blood purifier 10 performs hemofiltration on the blood taken from the patient A, using the hemofiltration membrane, and also performs dialysis on the blood using the dialysis membrane and the dialysate from the dialysate container 3. The blood purified by the blood purifier 10 is returned to the patient via the vein-side blood circuit 13. Further, the replacement fluid pump 8 sends the replacement fluid contained in the replacement fluid container 4 to the vein-side blood circuit 13, thereby mixing the replacement fluid into the blood purified by the blood purifier 10. As a result, the blood purified by the blood purifier 10 and the replacement fluid are returned to the patient A. Furthermore, the filtrate pump 9 sends the filtrate generated by the hemofiltration and the dialysis of the blood purifier 10, into the filtrate container 5 via the filtrate discard channel 14.

    [0055] Then, in the weight sensor 1, the first strain value sensor 27 detects a strain value of the first square bar 23a, the second strain value sensor 28 detects a strain value of the second square bar 23b, and the third strain value sensor 29 detects a strain value of the third square bar 23c (S2). The strain value of the first square bar 23a is a strain value corresponding to a sum (first sum) of: a weight of the filtrate in the filtrate container 5 held by the filtrate holder 24; a weight of the replacement fluid in the replacement fluid container 4 held by the replacement fluid holder 25; and a weight of the dialysate in the dialysate container 3 held by the dialysate holder 26. The strain value of the second square bar 23b is a strain value corresponding to a sum (second sum) of: the weight of the replacement fluid in the replacement fluid container 4 held by the replacement fluid holder 25; and the weight of the dialysate in the dialysate container 3 held by the dialysate holder 26. The strain value of the third square bar 23c is a strain value corresponding to on a sum (third sum) that is the weight of the dialysate in the dialysate container 3 held by the dialysate holder 26.

    [0056] The weight calculation unit 30 calculates a sum (the first sum) of: the weight of the filtrate in the filtrate container 5; the weight of the replacement fluid in the replacement fluid container 4; and the weight of the dialysate in the dialysate container 3, using the result detected by the first strain value sensor 27 and a relationship between the detected strain value and the weights. The weight calculation unlit 30 also calculates a sum (the second sum) of: the weight of the replacement fluid in the replacement fluid container 4; and the weight of the dialysate in the dialysate container 3, using the result detected by the second strain value sensor 28 and a relationship between the detected strain value and the weights. The weight calculation unit 30 further calculates a sum (the third sum) that is the weight of the dialysate in the dialysate container 3, using the results detected by the third strain value sensor 29 and a relationship between the detected strain value and the weight. In addition, the weight calculation unit 30 calculates the weight of the filtrate in the filtrate container 5 by subtracting the second sum from the first sum, and the weight of the replacement fluid in the replacement fluid container 4 by subtracting the third sum from the second sum (S3).

    [0057] Here, if there is a balance between (i) a total flow rate of used dialysate and used replacement fluid and (ii) a flow rate of discarded filtrate, an amount of decrease in dialysate in the dialysate container 3 and replacement fluid in the replacement fluid container 4 becomes equal to an amount of increase in filtrate in the filtrate container 5. This means that, in the above situation, the first sum is not changed as time passes.

    [0058] Then, the balance controller 2 controls the dialysate pump 7, the replacement fluid pump 8, and the filtrate pump 9 to keep, within respective predetermined ranges, the total flow rate of the using dialysate and using replacement fluid and the flow rate of the discarding filtrate, and at the same time, to keep the first sum to be constant (S4). In more detail, in the balance controller 2, the obtainment unit 41 obtains, from the weight calculation unlit 30 of the weight sensor 1, that sum (first sum) of: the weight of thy filtrate in the filtrate container 5; the weight of the replacement fluid in the replacement fluid container 4; and the weight of the dialysate in the dialysate container 3. The control unit 42 controls the dialysate pump 7, the replacement fluid pump 8, and the filtrate pump 9 to keep, within respective predetermined ranges, a total flow rate of the using dialysate and using replacement fluid and a flow rate of the discarding filtrate, and at the same time, to keep the first sum to be constant. This achieves a balance between (i) the total flow rate of the using dialysate and the using replacement fluid and (ii) the flow rate of the discarding filtrate.

    [0059] Based on the results calculated by the weight calculation unit 30, the increased/decreased amount calculation unit 31 calculates: an amount of increase in a weight of the filtrate in the filtrate container 5 from an initial weight of the filtrate; an amount of decrease in a weight of the replacement fluid in the replacement fluid container 4 from an initial weight of the replacement fluid; and an amount of decrease in a weight of the dialysate in the dialysate container 3 from an initial weight of the dialysate. In other words, the increased/decreased amount calculation unit 31 calculates: a weight of filtrate which has been discarded; a weight of replacement fluid which has been used; and a weight of dialysate which has been used.

    [0060] Based on the results calculated by the weight calculation unit 30, the temporal change amount calculation unit 32 calculates: a temporal change amount in a weight of the dialysate container 3; a temporal change amount in a weight of the replacement fluid container 4; and a temporal change amount in a weight of the filtrate container 5. In other words, the temporal change amount calculation unit 32 calculates: a flow rate of the filtrate contained in the filtrate container 5; a flow rate of the replacement fluid contained in the replacement fluid container 4; and a flow rate of dialysate contained in the dialysate container 3 (S5). In more detail, the temporal change amount calculation unit 32 calculates the flow rate of the filtrate, by dividing the temporal change amount of the weight of the filtrate calculated by the weight calculation unit 30, by a specific gravity of the filtrate. The temporal change amount calculation unit 32 also calculates the flow rate of the replacement fluid, by dividing the temporal change amount of the weight of the replacement fluid calculated by the weight calculation unit 30, by a specific gravity of the replacement fluid. The temporal change amount calculation unit 32 further calculates the flow rate of the dialysate, by dividing the temporal change amount of the weight of the dialysate calculated by the weight calculation unit 30, by a specific gravity of the dialysate.

    [0061] The display unit 33 displays, as shown in FIG. 6, the results calculated by the weight calculation unit. 30, the increased/decreased amount calculation unit 31, and the temporal change amount calculation unit 32 (S6). More specifically, the display unit 33 displays: the weigh of the filtrate in the filtrate container 5; the weight of the replacement fluid in the replacement fluid container 4; the weight of the dialysate in the dialysate container 3; the weight of the discarded filtrate; the weight of the used replacement fluid; the weight of the used dialysate; the flow rate of the filtrate contained in the filtrate container 5; the flow rate of the replacement fluid contained in the replacement fluid contained 4; and the flow rate of the dialysate contained in the dialysate container 3.

    [0062] The balance controller 2 determines whether or not a predetermined amount of blood has been purified (S7). If it is determined that the predetermined amount of blood has not yet been purified (No at S7), the processing returns to Step S2 where the first strain value sensor 27, the second strain value sensor 28, and the third strain value sensor 29 detect strain values of respective predetermined parts. On the other hand, if it is determined that the predetermined amount of blood has been purified (Yes at S7), the processing performed by the blood purification system according to the first example completes.

    [0063] As described above, in the blood purification system according to the first example, the balance controller 2 controls operations of the dialysate pump 7, the replacement fluid pump 8, and the filtrate pump 9, in order not to change a sum (first sum) of: a weight of filtrate in the filtrate container 5; a weight of replacement fluid in the replacement fluid container 4; and a weight of dialysate in the dialysate container 3. This achieves a balance between (i) a total flow rate of using dialysate and using replacement fluid and (ii) a flow rate of discarding filtrate.

    [0064] In addition, in the blood purification system according to the first example, the display unit 33 displays the results calculated by the weight calculation unit 30, the increased/decreased amount calculation unit 31, and the temporal change amount calculation unit 32. In other words, the blood purification system according to the first example displays: a weight of discarded filtrate; a weight of used replacement fluid; a weight of used dialysate; a flow rate of discarding filtrate; a flow rate of using replacement fluid; and a flow rate of using dialysate. Thereby, a physician can learn: the weight of discarded filtrate; the weight of used replacement fluid; the weight of used dialysate; the flow rate of discarding filtrate; the flow rate of using replacement fluid; and the flow rate of using dialysate.

    [0065] This means that the balance controller 2 according to the first example can achieve a balance between (i) a flow rate of blood taken from a patient and (ii) a total flow rate of blood returned to the patient and replacement fluid supplied to the patient, using the calculation results obtained by the weight sensor 1. In addition, the weight sensor 1 according to the first example correctly calculates: a weight of discarded filtrate; a weight of used replacement fluid; a weight of used dialysate; a flow rate of discarding filtrate; a flow rate of using replacement fluid; a flow rate of using dialysate, and then displays the calculation results.

    [0066] It should be noted that a set of the filtrate holder 24, the replacement fluid holder 25, and the dialysate holder 26 in the first example is an example of the "n holders" in the weight sensor. It should also be noted that a set of the first strain value sensor 27, the second strain value sensor 28, the third strain value sensor 29 in the first example is an example of the "n strain value sensors" in the weight sensor.

    [0067] It should also be note that the arm 23 is not limited to have a structure comprising of the first square bar 23a, the second square bar 23b, and the third square bar 23c. That is, the structure of the arm is not limited to have a plurality of square bars. The arm may be comprised of a single square bar only. When the arm is comprised of a single square bar, the arm has a through-hole between the pillar 22 and a holder proximate to the pillar 22, and other through-holes each provided between two neighboring holders. These through-holes are penetrating horizontally and in a direction perpendicular to the arm having a linear shape.

    [0068] It should also be note that, when the arm 23 is comprised of a plurality of bar-shaped members, each of the bar-shaped members is not limited to be a square bar, but may be a round bar or the like. When the arm 23 is comprised of a single bar-shaped member, the bar-shaped member is not limited to be a square bar, but may be a round bar or the like.

    [0069] It should also be note that the shape of the though-hole provided in the arm 23 in the cross section is hot limited to the bone shape, but the shape may be an ellipse or the like as shown as a through-hole 230a, a through-hole 230b, and a through-hole 230c in FIG. 8. Here, it is preferable that the shape of the through-hole in the cross section is symmetry with respect to a bisector of a line segment perpendicular to a longitudinal direction of the arm 23 in the cross section, and also symmetry with respect to a bisector of a line segment along the longitudinal direction of the arm 23 in the cross section.

    [0070] According to the present invention, when the arm 23 is comprised of a plurality of bar-shaped members, the plurality of bar-shaped members in the arm 23 mar are connected in a broken line so that the members form a square without one side as viewed from above, as shown in FIG. 9. The arm 23 may also be a single member having a shape of a broken line. The arm 23 may also have a shape of a circular or a curb so that the arm forms a "U" shape as viewed from above.

    It should also be note that the arm 23 may be made of any material such as titanium, if the material results in accurate detection of strain values.



    [0071] It should also be noted that the first strain value sensor 27, the second strain value sensor 28, and the third strain value sensor 29 are not limited to the Roberval strain value sensors. Each of the first strain value sensor 27, the second strain value sensor 28, and the third strain value sensor 29 may be anything capable of detecting a strain value that is a change in strain of the corresponding square bar resulting from a weight of the corresponding square bar. It should also be note that the arm 23 may be without any through-holes. In other words, the arm 23 may be comprised of one or more bar-shaped member without any through-hole, as far as the arm 23 has a means for detecting strain values with a high accuracy.

    (Second Example)



    [0072] The following describes a blood purification system according to a second example.

    [0073] It has been described in the first example that the blood purification system is used for medical treatments using the CHDF to purify blood of the patient A. However, the blood purification system according to the present invention sometimes uses the CHF in blood purification.

    [0074] In the second example of the present invention, a blood purification system using the CHF to purify blood is described.

    [0075] In the CHF, as previously explained, blood taken from a patient is supplied to a blood purifier having a hemofiltration membrane and applied with hemofiltration using the hemofiltration membrane, then the purified blood is returned to the patient, and waste products and solvent in the blood resulting from the hemofiltration is discarded. In addition, replacement fluid is supplied to blood of the patient. The above processing is performed continuously and slowly. Therefore, the medical treatments using the CHF differs from the medical treatments using the CHDF in that dialysate is not used. However, a balance between (i) a flow rate of using replacement fluid and (ii) a flow rate of discarding filtrate should be achieved to prevent deterioration of the patient's condition.

    [0076] Therefore, the blood purification system of the second example differs from the blood purification system of the first example of FIGS. 3 and 4 in that the arm 23 in the weight sensor 1 is replaced by a structure as shown in FIG. 10. FIG. 10 is a diagram showing a part of the weight sensor 1 according to the second example. The weight sensor 1 of the second example has most of the same elements as the elements of the weight sensor 1 of the first example. Therefore, FIG. 10 shows only some of the elements in the weight sensor 1 of the second example in order to clearly show a difference from the weight sensor 1 of the first example. In more detail, FIG. 10 shows the base 21, the pillar 22, an arm 23, the filtrate holder 24, the replacement fluid holder 25, a first strain value sensor 27, a second strain value sensor 28 in the weight sensor 1 according to the second example. FIG. 10 also shows the replacement fluid container 4 and the filtrate container 5.

    [0077] In the blood purification system according to the second example, the first strain value sensor 27 detects a strain value of the first square bar 23a corresponding to a sum (fourth sum) of: a weight of filtrate in the filtrate container 5 held by the filtrate holder 24; and a weight of replacement fluid in the replacement fluid container 4 held by the replacement fluid holder 25. The second strain value sensor 28 detects a strain value of the second square bar 23b corresponding to the weight (fifth sum) of the replacement fluid in the replacement fluid container 4 held by the replacement fluid holder 25.

    [0078] The weight calculation unit 30 calculates a sum of: the weigh of the filtrate in the filtrate container 5; and the weight of the replacement fluid in the replacement fluid container 4, using the results detected by the first strain value sensor 27 and a relationship between the detected strain value and the weights. The weight calculation unit 30 also calculates the weight of the replacement fluid in the replacement fluid container 4, using the result detected by the second strain value sensor 28 and a relationship between the detected strain value and the weight. The weight calculation unit 30 further calculates the weight of the filtrate in the filtrate container 5, by subtracting the fifth sum from the fourth sum.

    [0079] In the meanwhile, when there is a balance between (i) a flow rate of using replacement fluid and (ii) a flow rate of discarding filtrate, an amount of decrease in replacement fluid contained in the replacement fluid container is equal to an amount of increase in filtrate contained in the filtrate container 5, per unit time. This means that the fourth sum is not changed even if time passes.

    [0080] Then, the balance controller 2 controls operations of the replacement fluid pump 8 and the filtrate pump 9 in order to keep, within respective predetermined flow rates, a flow rate of using replacement fluid and a flow rate of discarding filtrate, and to thereby keep the fourth sum to be constant. In more detail, in the balance controller 2, the obtainment unit 41 obtains, from the weight calculation unit 30 in the weight sensor 1, a sum (the fourth sum) of: the weight of the filtrate in the filtrate container 5; and the weight of the replacement fluid in the replacement fluid container 4. The control unit 42 controls operations of the replacement fluid pump 8 and the filtrate pump 9 in order to keep, within respective predetermined flow rates, a flow rate of using replacement fluid and a flow rate of discarding filtrate, and to thereby keep the fourth sum to be constant. As a result, a balance between (i) a flow rate of using replacement fluid and (ii) a flow rate of discarding filtrate is achieved.

    [0081] The increased/decreased amount calculation unit 31 calculates: an amount of increase in a weight of filtrate in the filtrate container 5 calculated by the weight calculation unit 30 from an initial weight of filtrate; and an amount of decrease in a weight of replacement fluid in the replacement fluid container 4 calculated by the weight calculation unit 30 from an initial weight of replacement fluid. In short, the increased/decreased amount calculation unit 31 calculates a weight of filtrate which has been discarded and a weight of replacement fluid which has been used.

    [0082] Based on the weight of the filtrate in the filtrate container 5 and the weight of the replacement fluid in the replacement fluid container 4 calculated by the weight calculation unit 30, the temporal change amount calculation unit 32 calculates: a flow rate of filtrate contained in the filtrate container 5; and a flow rate of replacement fluid contained in the replacement fluid container 4.

    [0083] Based on the weight of the filtrate in the filtrate container 5, the temporal change amount calculation unit 32 calculates a flow rate of the filtrate contained in the filtrate container 5, which is an amount of temporal increase in a weight of the filtrate in the filtrate container 5. Likewise, based on the weight of the replacement fluid in the replacement fluid container 4, the temporal change amount calculation unit 32 calculates a flow rate of the replacement fluid contained in the replacement fluid container 4, which is an amount of temporal decrease in a weight of the replacement fluid in the replacement fluid container 4.

    [0084] The display unit 33 displays the results calculated by the weight calculation unit 30, the increased/decreased amount calculation unit 31, and the temporal change amount calculation unit 32. In other words, the display unit 33 displays: the weigh of the filtrate in the filtrate container 5; the weight of the replacement fluid in the replacement fluid container 4; the weight of discarded filtrate; the weight of used replacement fluid; the flow of the filtrate contained in the filtrate container 5; and the flow rate of the replacement fluid contained in the replacement fluid container 4. Thereby, a physician can learn : the weight of the discarded filtrate; the weight of the used replacement fluid; the flow rate of discarding filtrate, and the flow rate of using replacement fluid.

    [0085] As described above, the blood purification system according to second example, the balance controller 2 controls operations of the replacement fluid pump 8 and the filtrate pump 9 so that the fourth sum is not changed as time passes. As a result, a balance between (i) a flow rate of using replacement fluid and (ii) a flow rate of discarding filtrate is achieved.

    [0086] In addition, in the blood purification system according to the second example, the display unit 33 displays the results calculated by the weight calculation unit 30, the increased/decreased amount calculation unit 31, and the temporal change amount calculation unit 32. In more detail, the blood purification system according to the second example displays: the weight of the discarded filtrate; the weight of the used replacement fluid; the flow rate of discarding filtrate; and the flow rate of the using replacement fluid. Thereby, a physician can learn: the weight of discarded filtrate; the weight of used replacement fluid; the flow rate of discarding filtrate; and the flow rate of using replacement fluid.

    [0087] It has been described in the above embodiments that the weight sensor and the balance controller according to the present invention are used in the blood purification system for performing medical treatments using the CHDF and the CHF to purify blood of the patient A. However, the weight sensor and the balance controller according to the present invention are not limited to be used in the blood purification system for performing medical treatments using the CHDF and the CHF to purify blood of the patient A. The weight sensor according to the present invention can be used to achieve a balance among weights of a plurality of substances and to detect respective weights of the substances. Therefore, although the n holders in the weight sensor according to the aspect of the present invention have been described in the above embodiments as the filtrate holder 24, the replacement fluid holder 25, and the dialysate holder 26, "n" is not limited to 3 or 2. Likewise, the number of the n strain value sensors in the weight sensor according to the aspect of the present invention is not limited. Furthermore, the balance controller according to the present invention achieves a balance among weights of a plurality of substances, using results generated by the weight sensor according to the present invention.

    Industrial Applicability



    [0088] The weight sensor according to the present invention is useful as a device or the like to be used for balancing between (i) a flow rate of blood taken from a patient and (ii) a total flow rate of blood returned to the patient and replacement fluid supplied to the patient, in medical treatments using the CHF or the CHDF to purify blood of a patient such as a patient with renal function insufficiency. Furthermore, the balance controller according to the present invention is useful as a device or the like which achieves the balance between (i) the flow rate of blood taken from the patient and (ii) the total flow rate of the blood returned to the patient and the replacement fluid supplied to the patient, based on results calculated by the weight sensor according to the present invention.


    Claims

    1. A weight sensor (1) comprising:

    a pillar (22);

    an arm (23) having an end fixed to said pillar (22) and a free end;

    n holders (24, 25, 26), provided at n locations on a side surface of said arm (23) arranged along a longitudinal direction, respectively, each of which is configured to hold a substance, n being a natural number equal to or greater than two;

    n strain value sensors (27, 28, 29), provided on said arm (23) in association with n sums, respectively, each of which is configured to detect a strain value of said arm (23) corresponding to a corresponding sum among the n sums, the corresponding sum being a sum of weights of the substances held by said holders (24, 25, 26) ranging from a holder (26) proximate to the free end to a m-th holder counted from said pillar (22), and m being a natural number ranging from 1 to n; and

    a weight calculation unit (30) configured to calculate the n sums based on results of the detection of said n strain value sensors (27, 28, 29),

    characterized in that said arm forms a "U" shape as viewed from above.


     
    2. The weight sensor according to Claim 1,
    wherein said weight calculation unit (30) is configured to calculate the weights of the substances held by said n holders (24, 25, 26), respectively, based on results of the detection of said n strain value sensors (27, 28, 29).
     
    3. The weight sensor according to Claim 1 further comprising
    a display unit (33) configured to display results of the calculation of said weight calculation unit (30).
     
    4. The weight sensor according to Claim 1,
    wherein said arm (23) is a member including n bar-shaped members (23a, 23b, 23c) connected in series at each end,
    each of said n bar-shaped members (23a, 23b, 23c) has a through-hole penetrating in a direction perpendicular to the longitudinal direction of said arm (23) without penetrating the side surface of the arm, on which the n holders are provided, and
    said n holders (24, 25, 26) are provided on said n bar-shaped members (23a, 23b, 23c), respectively.
     
    5. The weight sensor according to Claim 4,
    wherein a shape of the through-hole in a cross section is symmetry with respect to a bisector of a line segment perpendicular to the longitudinal direction of said arm (23) in the cross section of the through-hole, and also symmetry with respect to a bisector of a line segment along the longitudinal direction of said arm (23) in the cross section of the through-hole.
     
    6. The weight sensor according to Claim 5,
    wherein a size of each of a closer end and a farther end of the cross section of the through-hole is larger than a size of a part of the cross section of the through-hole between the closer end and the farther end, the closer end being closer to said pillar (22) and an farther end being farther from said pillar (22).
     
    7. The weight sensor according to Claim 4,
    wherein said n strain value sensors (27, 28, 29) are Roberval strain value sensors provided on said n bar-shaped members (23a, 23b, 23c), respectively.
     
    8. The weight sensor according to Claim 1,
    wherein said arm (23) has through-holes each of which penetrates in a direction perpendicular to the longitudinal direction of said arm (23) without penetrating the side surface of the arm, on which the n holders are provided, the through-holes being provided between said pillar (22) and the holder proximate to said pillar (22) and between two neighboring holders, respectively.
     
    9. The weight sensor according to Claim 8,
    wherein a shape of each of the through-holes in a cross section is symmetry with respect to a bisector of a line segment perpendicular to the longitudinal direction of said arm (23) in the cross section of the through-hole, and also symmetry with respect to a bisector of a line segment along the longitudinal direction of said arm (23) in the cross section of the through-hole.
     
    10. The weight sensor according to Claim 9,
    wherein a size of each of a closer end and a farther end of the cross section of the through-hole is larger than a size of a part of the cross section of the through-hole between the closer end and the farther end, the closer end being closer to said pillar (22) and an farther end being farther from said pillar (22).
     
    11. The weight sensor according to Claim 8,
    wherein said n strain value sensors (27, 28, 29) are Roberval strain value sensors, and
    said n strain value sensors (27, 28, 29) are provided between said pillar (22) and the holder proximate to said pillar (22) and between the two neighbor holders (24, 25, 26), respectively and separately.
     
    12. The weight sensor according to Claim 1 further comprising,
    an increased/decreased amount calculation unit (31) configured to calculate an amount of increase or decrease in a weight of the substance held by each of said n holders (24, 25, 26) from an initial weight of the substance, based on results of the calculation of said n weight calculation units (30).
     
    13. The weight sensor according to Claim 1 further comprising
    a temporal change amount calculation unit (32) configured to calculate an amount of a temporal change in a weight of the substance held by each of said n holders (24, 25, 26), based on results of the calculation of said n weight calculation units (30).
     
    14. A blood purification system comprising a balance controller and a weight sensor of anyone of claims 1-13, comprising:

    an obtainment unit (41) configured to obtain a sum of weights of substances calculated by said weight sensor, the substances being held by the holders (24, 25, 26) that are from a holder proximate to the free end of the arm (23) to a holder proximate to said pillar (22); and

    a control unit (42) configured to control temporal change amounts of the weights of the substances held by the holders (24, 25, 26), respectively, in order to keep the sum obtained by said obtainment unit within a predetermined range.


     
    15. The blood purification system according to Claim 14,
    wherein the number of the holders (24, 25, 26) is three,
    a first holder in the holders (24, 25, 26) holds filtrate, a second holder in the holders (24, 25, 26) holds replacement fluid, and a third holder in the holders (24, 25, 26) holds dialysate, and
    said control unit (42) is configured to keep a sum of a weight of the filtrate, a weight of the replacement fluid, and a weight of the dialysate within a predetermined range, so as to balance between an amount of temporal increase in the filtrate and an amount of temporal decrease in the replacement fluid and the dialysate.
     
    16. The blood purification system according to Claim 14,
    wherein the number of the n holders (24, 25, 26) is two,
    a first holder in the holders (24, 25, 26) holds filtrate, and a second holder in the holders (24, 25, 26) holds replacement fluid, and
    said control unit (42) is configured to keep a sum of a weigh of the filtrate and a weight of the replacement fluid within a predetermined range, so as to balance between an amount of temporal increase in the filtrate and an amount of temporal decrease in the replacement fluid.
     


    Ansprüche

    1. Gewichtssensor (1), aufweisend:

    eine Säule (22);

    einen Arm (23), aufweisend ein an der Säule (22) befestigtes Ende und ein freies Ende;

    n Halter (24, 25, 26), bereitgestellt an n Stellen auf einer Seitenfläche des Arms (23), jeweils angeordnet entlang einer Längsrichtung, von denen jeder für ein Halten einer Substanz konfiguriert ist, wobei n eine natürliche Zahl ist, die gleich groß wie oder größer als zwei ist;

    n Dehnungswertsensoren (27, 28, 29), bereitgestellt auf dem Arm (23) in Verbindung mit jeweils n Summen, von denen jeder konfiguriert ist für ein Erfassen eines Dehnungswerts des Arms (23), der einer entsprechenden Summe unter den n Summen entspricht, wobei die entsprechende Summe eine Summe von Gewichten der Substanzen ist, die von den Haltern (24, 25, 26) gehalten werden, von einem zum freien Ende benachbarten Halter (26) bis zu einem ab der Säule (22) gerechneten m-ten Halter, wobei m eine natürliche Zahl im Bereich von 1 bis n ist; und

    eine Gewichtsberechnungseinheit (30), die für ein Berechnen der n Summen auf Basis der Ergebnisse der Erfassung der n Dehnungswertsensoren (27, 28, 29) konfiguriert ist,

    dadurch gekennzeichnet, dass der Arm bei Draufsicht eine "U"-Form bildet.


     
    2. Gewichtssensor nach Anspruch 1,
    wobei die Gewichtsberechnungseinheit (30) für ein Berechnen der jeweiligen Gewichte der von den n Haltern (24, 25, 26) gehaltenen Substanzen auf Basis der Ergebnisse der Erfassung durch die n Dehnungswertsensoren (27, 28, 29) konfiguriert ist.
     
    3. Gewichtssensor nach Anspruch 1, ferner aufweisend
    eine Anzeigeeinheit (33), die für ein Anzeigen der Ergebnisse der Berechnung der Gewichtsberechnungseinheit (30) konfiguriert ist.
     
    4. Gewichtssensor nach Anspruch 1,
    wobei der Arm (23) ein Element ist, das n stabförmige Elemente (23a, 32b, 23c) aufweist, die an jedem Ende in Serie miteinander verbunden sind,
    jedes der n stabförmigen Elemente (23a, 32b, 23c) ein Durchgangsloch aufweist, das in einer zur Längsrichtung des Arms (23) rechtwinkligen Richtung penetriert, ohne die Seitenfläche des Arms, auf der die n Halter bereitgestellt sind, zu penetrieren, und
    die n Halter (24, 25, 26) jeweils auf den n stabförmigen Elementen (23a, 32b, 23c) bereitgestellt sind.
     
    5. Gewichtssensor nach Anspruch 4,
    wobei eine Form des Durchgangslochs in einem Querschnitt symmetrisch in Bezug auf eine Halbierende eines Liniensegments rechtwinklig zur Längsrichtung des Arms (23) im Querschnitt des Durchgangslochs und auch symmetrisch in Bezug auf eine Halbierende eines Liniensegments entlang der Längsrichtung des Arms (23) im Querschnitt des Durchgangslochs ist.
     
    6. Gewichtssensor nach Anspruch 5,
    wobei eine Größe jedes von einem näheren und einem ferneren Endes des Querschnitts des Durchgangslochs größer ist als eine Größe eines Teils des Querschnitts des Durchgangslochs zwischen dem näheren und dem ferneren Ende, wobei das nähere Ende näher an der Säule (22) und ein ferneres Ende ferner von der Säule (22) ist.
     
    7. Gewichtssensor nach Anspruch 4,
    wobei die n Dehnungswertsensoren (27, 28, 29) Roberval-Dehnungswertsensoren sind, die jeweils auf den n stabförmigen Elementen (23a, 32b, 23c) bereitgestellt sind.
     
    8. Gewichtssensor nach Anspruch 1,
    wobei der Arm (23) Durchgangslöcher aufweist, die jedes in einer zur Längsrichtung des Arms (23) rechtwinkligen Richtung penetrieren, ohne die Seitenfläche des Arms, auf der die n Halter bereitgestellt sind, zu penetrieren, wobei die Durchgangslöcher jeweils zwischen der Säule (22) und dem Halter nahe der Säule (22) und zwischen zwei benachbarten Haltern bereitgestellt sind.
     
    9. Gewichtssensor nach Anspruch 8,
    wobei eine Form jedes der Durchgangslöcher in einem Querschnitt symmetrisch in Bezug auf eine Halbierende eines Liniensegments rechtwinklig zur Längsrichtung des Arms (23) im Querschnitt des Durchgangslochs und auch symmetrisch in Bezug auf eine Halbierende eines Liniensegments entlang der Längsrichtung des Arms (23) im Querschnitt des Durchgangslochs ist.
     
    10. Gewichtssensor nach Anspruch 9,
    wobei eine Größe jedes von einem näheren und einem ferneren Endes des Querschnitts des Durchgangslochs größer ist als eine Größe eines Teils des Querschnitts des Durchgangslochs zwischen dem näheren und dem ferneren Ende, wobei das nähere Ende näher an der Säule (22) und ein ferneres Ende ferner von der Säule (22) ist.
     
    11. Gewichtssensor nach Anspruch 8,
    wobei die n Dehnungswertsensoren (27, 28, 29) Roberval-Dehnungswertsensoren sind, und
    die n Dehnungswertsensoren (27, 28, 29) jeweils getrennt zwischen der Säule (22) und dem Halter nahe der Säule (22) und zwischen zwei benachbarten Haltern (24, 25, 26) bereitgestellt sind.
     
    12. Gewichtssensor nach Anspruch 1, ferner aufweisend,
    eine Mengenzunahme-/-abnahme-Berechnungseinheit (31), die für ein Berechnen einer Menge von Zunahme oder Abnahme eines Gewichts der von jedem der n Halter (24, 25, 26) gehaltenen Substanz von einem Anfangsgewicht der Substanz auf Basis von Ergebnissen der Berechnung der n Gewichtsberechnungseinheiten (30), konfiguriert ist.
     
    13. Gewichtssensor nach Anspruch 1, ferner aufweisend,
    eine Zeitliche-Änderungsmengen-Berechnungseinheit (32), die für ein Berechnen einer Menge einer zeitlichen Änderung eines Gewichts der von jedem der n Halter (24, 25, 26) gehaltenen Substanz, auf Basis von Ergebnissen der Berechnung der n Gewichtsberechnungseinheiten (30), konfiguriert ist.
     
    14. Blutreinigungssystem, aufweisend eine Balancesteuerung und einen Gewichtssensor nach einem der Ansprüche 1 bis 13, aufweisend:

    eine Ermittlungseinheit (41), die für ein Ermitteln einer Summe von Gewichten von durch den Gewichtssensor berechneten Substanzen konfiguriert sind, wobei die Substanzen von den Haltern (24, 25, 26) gehalten werden, von einem Halter nahe des freien Endes des Arms (23) bis zu einem Halter nahe der Säule (22); und

    eine Steuereinheit (42), die für ein Steuern der zeitlichen Änderungsmengen der jeweils von den Haltern (24, 25, 26) gehaltenen Substanzen konfiguriert ist, um die von der Ermittlungseinheit ermittelte Summe innerhalb eines im Voraus bestimmten Bereichs zu halten.


     
    15. Blutreinigungssystem nach Anspruch 14,
    wobei die Anzahl der Halter (24, 25, 26) drei beträgt,
    ein erster Halter der Halter (24, 25, 26) Filtrat hält, ein zweiter Halter der Halter (24, 25, 26) Ersatzfluid hält, und ein dritter Halter der Halter (24, 25, 26) Dialysat hält, und
    die Steuereinheit (42) konfiguriert ist, um eine Summe eines Gewichts des Filtrats, eines Gewichts des Ersatzfluids und eines Gewichts des Dialysats innerhalb eines im Voraus bestimmten Bereichs zu halten, um eine Balance zwischen einer Menge zeitlicher Zunahme des Filtrats und einer Menge zeitlicher Abnahme des Ersatzfluids und des Dialysats zu halten.
     
    16. Blutreinigungssystem nach Anspruch 14,
    wobei die Anzahl der Halter (24, 25, 26) zwei beträgt,
    ein erster Halter der Halter (24, 25, 26) Filtrat hält und ein zweiter Halter der Halter (24, 25, 26) Ersatzfluid hält, und
    die Steuereinheit (42) konfiguriert ist, um eine Summe eines Gewichts des Filtrats und eines Gewichts des Ersatzfluids innerhalb eines im Voraus bestimmten Bereichs zu halten, um eine Balance zwischen einer Menge zeitlicher Zunahme des Filtrats und einer Menge zeitlicher Abnahme des Ersatzfluids zu halten.
     


    Revendications

    1. Capteur de poids (1) comprenant :

    une colonne (22) ;

    un bras (23) ayant une extrémité fixée à ladite colonne (22) et une extrémité libre ;

    n supports (24, 25, 26) fournis à n emplacements sur une surface latérale dudit bras (23) agencés le long d'une direction longitudinale, respectivement, chacun d'entre eux étant configuré pour supporter une substance, n étant un nombre naturel égal ou supérieur à deux ;

    n capteurs de valeur de tension (27, 28, 29) fournis sur ledit bras (23) en associations avec n sommes, respectivement, donc chacun est configuré pour détecter une valeur de tension dudit bras (23) correspondant à une somme correspondante parmi les n sommes, la somme correspondante étant une somme de poids des substances supportées par lesdits supports (24, 25, 26) allant d'un support (26) à proximité de l'extrémité libre à un mième support compté à partir de ladite colonne (22), et m étant un nombre naturel allant de 1 à n ; et

    une unité de calcul de poids (30) configurée pour calculer les n sommes sur la base de résultats de la détection desdits n capteurs de valeur de tension (27, 28, 29),

    caractérisé en ce que ledit bras est en forme de « U » vu du dessus.


     
    2. Capteur de poids selon la revendication 1,
    dans lequel ladite unité de calcul de poids (30) est configurée pour calculer les poids des substances supportées par lesdits n supports (24, 25, 26), respectivement, sur la base des résultats de la détection desdits n capteurs de valeur de tension (27, 28, 29).
     
    3. Capteur de poids selon la revendication 1, comprenant en outre
    une unité d'affichage (33) configurée pour afficher des résultats du calcul de ladite unité de calcul de poids (30).
     
    4. Capteur de poids selon la revendication 1,
    dans lequel ledit bras (23) est un élément comprenant n éléments en forme de barre (23a, 23b, 23c) reliés en série à chaque extrémité,
    chacun desdits éléments en forme de barre (23a, 23b, 23c) ayant un trou traversant pénétrant dans une direction perpendiculaire à la direction longitudinale dudit bras (23) sans pénétrer la surface latérale du bras, sur laquelle sont fournis les n supports, et
    lesdits n supports (24, 25, 26) sont fournis sur lesdits n éléments en forme de barre (23a, 23b, 23c) respectivement.
     
    5. Capteur de poids selon la revendication 4,
    dans lequel une forme du trou traversant en coupe transversale est symétrique par rapport à une bissectrice d'un segment de ligne perpendiculaire à la direction longitudinale dudit bras (23) dans la coupe transversale du trou traversant, et est également symétrique par rapport à une bissectrice d'un segment de ligne suivant la direction longitudinale dudit bras (23) dans la coupe transversale dudit trou traversant.
     
    6. Capteur de poids selon la revendication 5,
    dans lequel une dimension de chacune d'une extrémité plus à proximité et d'une extrémité plus éloignée de la coupe transversale du trou traversant est supérieure à une dimension d'une partie de la coupe transversale du trou traversant entre l'extrémité plus à proximité et l'extrémité plus éloignée, l'extrémité plus à proximité étant plus à proximité de ladite colonne (22) et une extrémité plus éloignée étant plus éloignée de ladite colonne (22).
     
    7. Capteur de poids selon la revendication 4,
    dans lequel lesdits n capteurs de valeur de tension (27, 28, 29) sont des capteurs de valeur de tension Roberval fournis sur lesdits n éléments en forme de barre (23a, 23b, 23c) respectivement.
     
    8. Capteur de poids selon la revendication 1,
    dans lequel ledit bras (23) a des trous traversants, chacun d'entre eux pénétrant dans une direction perpendiculaire à la direction longitudinale dudit bras (23) sans pénétrer la surface latérale du bras, sur laquelle sont fournis les n supports, les trous traversants étant fournis entre ladite colonne (22) et le support à proximité de ladite colonne (22) et entre deux supports avoisinants, respectivement.
     
    9. Capteur de poids selon la revendication 8,
    dans lequel une forme de chacun des trous traversants dans une coupe transversale est symétrique par rapport à une bissectrice d'un segment de ligne perpendiculaire à la direction longitudinale dudit bras (23) dans la coupe transversale du trou traversant et est également symétrique par rapport à une bissectrice d'un segment de ligne suivant une direction longitudinale dudit bras (23) dans la coupe transversale du trou traversant.
     
    10. Capteur de poids selon la revendication 9,
    dans lequel une dimension de chacune d'une extrémité plus à proximité et d'une extrémité plus éloignée de la coupe transversale du trou traversant est supérieure à une dimension d'une partie de la coupe transversale du trou traversant entre l'extrémité plus à proximité et l'extrémité plus éloignée, l'extrémité plus à proximité étant plus à proximité de ladite colonne (22) et une extrémité plus éloignée étant plus éloignée de ladite colonne (22).
     
    11. Capteur de poids selon la revendication 8,
    dans lequel lesdits n capteurs de valeur de tension (27, 28, 29) sont des capteurs de valeur de tension Roberval, et
    lesdits n capteurs de valeur de tension (27, 28, 29) sont fournis entre ladite colonne (22) et ledit support à proximité de ladite colonne (22) et entre les deux supports avoisinants (24, 25, 26) respectivement et séparément.
     
    12. Capteur de poids selon la revendication 1, comprenant en outre :

    une unité de calcul de quantité augmentée/réduite (31) configurée pour calculer une quantité d'augmentation ou de réduction d'un poids de la substance supportée par chacun desdits n supports (24, 25, 26) à partir d'un poids initial de la substance, sur la base de résultats du calcul desdites n unités de calcul de poids (30).


     
    13. Capteur de poids selon la revendication 1, comprenant en outre
    une unité de calcul de quantité de changement temporel (32) configurée pour calculer une quantité de changement temporel d'un poids de la substance supportée par chacun desdits n supports (24, 25, 26), sur la base de résultats du calcul desdites n unités de calcul de poids (30).
     
    14. Système de purification de sang comprenant un contrôleur d'équilibre et un capteur de poids selon l'une quelconque des revendications 1 à 13, comprenant :

    une unité d'obtention (41) configurée pour obtenir une somme de poids de substances calculées par ledit capteur de poids, les substances étant supportées par les supports (24, 25, 26) qui vont d'un support à proximité de l'extrémité libre du bras (23) à un support à proximité de ladite colonne (22) ; et

    une unité de commande (42) configurée pour commander les quantités de changement temporel des poids des substances supportées par les supports (24, 25, 26) respectivement, afin de maintenir la somme obtenue par ladite unité d'obtention dans une certaine plage prédéterminée.


     
    15. Système de purification de sang selon la revendication 14,
    dans lequel les supports (24, 25, 26) sont au nombre de trois,
    un premier support des supports (24, 25, 26) supporte un filtrat, un deuxième support des supports (24, 25, 26) supporte un liquide de remplacement et un troisième support des supports (24, 25, 26) supporte un liquide de dialyse, et
    ladite unité de commande (42) est configurée pour conserver une somme d'un poids du filtrat, un poids du liquide de remplacement et un poids du liquide de dialyse dans une plage prédéterminée de façon à assurer un équilibre entre une quantité d'augmentation temporelle dans le filtrat et une quantité de réduction temporelle dans le liquide de remplacement et le liquide de dialyse.
     
    16. Système de purification de sang selon la revendication 14,
    dans lequel les n supports (24, 25, 26) sont au nombre de deux,
    un premier support des supports (24, 25, 26) supporte un filtrat et un second support des supports (24, 25, 26) supporte un liquide de remplacement, et
    ladite unité de commande (42) est configurée pour conserver une somme d'un poids du filtrat et un poids du liquide de remplacement dans une plage prédéterminée de façon à assurer un équilibre entre une quantité d'augmentation temporelle dans le filtrat et une quantité de réduction temporelle dans le liquide de remplacement.
     




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    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description