System and method for producing fluid for peritoneal dialysis

Abstract

A system (1) and method for producing fluid for peritoneal dialysis (PD). The system (1) comprises a fluid path (2) comprising one or more PD concentrate connectors (3a, 3b) each configured to be connected to a source (4a, 4b) of one or more PD concentrates, and a water connector (7a) configured to be connected to a source of water. The system (1) further comprises a forward osmosis (FO) unit (6) comprising a draw side (6a) and a feed side (6b) separated by a FO membrane (6c). The FO unit (6) is fluidically connected to the fluid path (2). The FO unit (6) is configured to receive the one or more PD concentrate fluids at the draw side (6a) and water at the feed side (6b), wherein purified water is transported through the FO membrane (6c) to the one or more PD concentrate fluids by means of an osmotic pressure gradient between the draw side (6a) and the feed side (6b), wherein the transported purified water is further purified by the FO membrane (6c), and wherein the one or more PD concentrate fluids are diluted to produce diluted PD concentrate fluids.

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of peritoneal dialysis and to a system and method for producing fluid for use in peritoneal dialysis. BACKGROUND

[0002] Peritoneal dialysis (PD) is a method for treating patients suffering from kidney failure. During PD, the patient's peritoneal cavity is filled with fresh PD fluid and waste and liquid is transported from the patient's blood to the PD fluid via the peritoneum. The used PD fluid is subsequently drained from the patient.

[0003] There are several kinds of PD. In automated peritoneal dialysis (APD), a machine is used to fill the peritoneal cavity with fresh PD fluid and after a certain pause time, the machine drains the used PD solution from the body. The procedure is repeated several times, usually during the night. In continuous flow peritoneal dialysis (CFPD), for example, a machine is used to provide a continuous flow of fresh PD fluid to the patient's peritoneal cavity and a continuous flow of used PD fluid from the patient. The APD systems on the market today use centrally manufactured PD fluid, which is shipped to the patient, ready for use in bags stored at the patient's home.

[0004] The transport of PD fluid increases the handling costs and has a negative impact on the environment. The storage of PD fluid at the patient's home is very space demanding. The handling of PD fluid by the patient before treatment increases the burden on the patient, many of whom find it difficult to place the PD fluid bags in the correct location before the treatment starts.

[0005] There is therefore a need to reduce the negative consequences listed above. SUMMARY

[0006] It is an object of the present disclosure to alleviate at least some of the drawbacks of the prior art. Another object is to provide a cost-effective solution for producing fluid for PD at the point of care. Yet another object is to provide a simple solution for producing fluid for PD at the point of care. Still another object is to provide a PD fluid solution that consumes a small amount of water.

[0007] These and other objects are at least partially achieved by the system and method according to the independent claims and by the embodiments according to the dependent claims.

[0008] According to an aspect which can be combined with any other aspect or part of the present disclosure, the present disclosure relates to a system for producing a fluid for peritoneal dialysis (PD). The system comprises a fluid path comprising one or more PD concentrate connectors configured to be connected to one or more sources of PD concentrate fluid and a water connector configured to be connected to a source of water. The system further comprises a forward osmosis (FO) unit comprising a draw side and a feed side separated by a FO membrane, the FO unit being fluidically connected to the fluid path. The FO unit is configured to receive the one or more PD concentrate fluids at the draw side and to receive water at the feed side to deliver purified water from the water to the one or more PD concentrate fluids through the FO membrane by means of an osmotic pressure gradient between the draw side and the feed side. The one or more PD concentrate fluids are thus diluted to produce a diluted PD concentrate fluid. The proposed system can purify water while rediluting PD concentrate, whereby water purification can be made less complex and less costly. In embodiments, the delivered purified water is further purified by the FO membrane of the FO unit.

[0009] According to another aspect which can be combined with any other aspect or part of the present disclosure, the system comprises a concentration sensor configured to sense a concentration of the diluted PD concentrate fluid and a control device configured to control a degree of dilution of the one or more PD concentrates during production of the diluted PD concentrate fluid based on the sensed concentration so as to meet one or more predetermined criteria.

[0010] According to another aspect which can be combined with any other aspect or part of the present disclosure, the one or more predetermined criteria comprise that the concentration of the diluted PD concentrate fluid has a concentration equal to or close to (e.g. at least substantially equal to) a concentration matching a prescribed concentration of the diluted PD fluid in a final PD fluid, that the concentration of the diluted PD concentrate fluid corresponds to a final degree of dilution of the PD fluid, and / or that the concentration of the diluted PD concentrate fluid is within a concentration interval for a certain time.

[0011] According to another aspect which can be combined with any other aspect or part of the present disclosure, the control device is configured to control the degree of dilution of the one or more PD concentrates by controlling a flow rate of the one or more PD concentrate fluids to an inlet of the draw side, and / or controlling a flow rate of water to an inlet of the feed side, and / or controlling a flow rate of waste water from an outlet of the feed side.

[0012] According to another aspect which can be combined with any other aspect or part of the present disclosure, the system comprises a container fluidically connected or connectable to the fluid path, wherein the container is arranged to hold the diluted PD concentrate fluid.

[0013] According to another aspect, which can be combined with any other aspect or part of the present disclosure, the fluid path comprises a first recirculation fluid path comprising the container and a draw side of the FO unit. The control device is configured to control the degree of dilution by recirculating the diluted concentrate fluid in the first recirculation fluid path until one or more predetermined criteria are met.

[0014] According to another aspect, which can be combined with any other aspect or part of the present disclosure, the system comprises a pump positioned and arranged to at least one of: (i) transfer the diluted PD concentrate fluid to the container along the line or (ii) remove the diluted PD concentrate fluid from the container along the line.

[0015] According to another aspect, which can be combined with any other aspect or part of the present disclosure, the system comprises at least one of: (i) a fluid heater positioned along the line, (ii) a concentrate pump in the recirculation fluid path, wherein the concentrate pump is optionally placed in fluid parallel with the valve, or (iii) an air / fluid sensor in the recirculation fluid path for determining when the PD concentrate fluid has reached the sensor.

[0016] According to another aspect, which can be combined with any other aspect or part of the present disclosure, the fluid path comprises a second recirculation fluid path comprising a feed side of the FO unit, wherein the control device is configured to recirculate water in the second recirculation fluid path until one or more predetermined criteria are met.

[0017] According to another aspect, which can be combined with any other aspect or part of the present disclosure, the control device is configured to direct the diluted PD concentrate fluid to an outlet connector upon meeting one or more predetermined criteria.

[0018] According to another aspect, which can be combined with any other aspect or part of the present disclosure, the system comprises a water container configured to collect water downstream of the FO unit.

[0019] According to another aspect, which can be combined with any other aspect or part of the present disclosure, the fluid path comprises a permeate connector configured to be connected to a permeate source, and wherein the control device is configured to supply permeate from the permeate source to the fluid path to achieve a prescribed concentration of permeate in the diluted PD concentrate fluid.

[0020] According to another aspect, which can be combined with any other aspect or part of the present disclosure, the fluid path comprises an inlet connector configured to be connected to a source of effluent. The FO unit is configured to receive the effluent at the feed side to transport water from the effluent to the one or more PD concentrate fluids through the FO membrane by means of the osmotic pressure gradient between the draw side and the feed side. Accordingly, the one or more PD concentrate fluids are diluted to produce a pre-diluted PD concentrate fluid, wherein the pre-diluted concentrate fluid is comprised in the one or more PD concentrate fluids that the FO unit is configured to receive.

[0021] According to another aspect, which can be combined with any other aspect or part of the present disclosure, the system comprises an effluent container fluidically connected or connectable to the fluid path, wherein the container is arranged to contain effluent from the patient.

[0022] According to another aspect, which can be combined with any other aspect or part of the present disclosure, the system comprises a pre-treatment unit configured to pre-treat water received via the water connector before the water received via the water connector is passed to the FO unit.

[0023] According to another aspect, which can be combined with any other aspect or part of the present disclosure, the present disclosure comprises a method for producing a fluid for peritoneal dialysis (PD) in a system comprising a forward osmosis (FO) unit. The FO unit comprises a draw side and a feed side separated by a FO membrane. The FO unit is configured to receive one or more PD concentrate fluids at the draw side and water at the feed side to transport purified water from the water to the one or more PD concentrate fluids through the FO membrane by means of an osmotic pressure gradient between the draw side and the feed side, thereby diluting the one or more PD concentrate fluids into a diluted PD concentrate fluid. The method comprises directing water to the feed side of the FO unit and directing the one or more PD concentrate fluids to the draw side.

[0024] According to another aspect, which can be combined with any other aspect or part of the present disclosure, the method comprises sensing a concentration of the diluted PD concentrate fluid and controlling a degree of dilution of the one or more PD concentrate fluids during the production of the diluted PD concentrate fluid based on the sensed concentration, thereby satisfying one or more predetermined criteria.

[0025] According to another aspect, which can be combined with any other aspect or part of the present disclosure, the one or more predetermined criteria comprises that the concentration of the diluted PD concentrate fluid has a concentration equal to or close to (e.g. at least substantially equal to) a prescribed concentration of the diluted PD fluid in the final PD fluid; that the concentration of the diluted PD concentrate fluid corresponds to a final degree of dilution of the PD fluid; and / or that the concentration of the diluted PD concentrate fluid is within a concentration interval for a certain time.

[0026] According to another aspect, which can be combined with any other aspect or part of the present disclosure, the method comprises controlling the degree of dilution of the one or more PD concentrates by controlling the flow rate of the one or more PD concentrate fluids to the inlet of the draw side, and / or controlling the flow rate of water at the inlet of the feed side, and / or controlling the flow rate of the waste water from the outlet of the feed side.

[0027] According to another aspect, which can be combined with any other aspect or part of the present disclosure, the method comprises directing the diluted PD concentrate fluid into a container.

[0028] According to another aspect, which can be combined with any other aspect or part of the present disclosure, the method comprises controlling the degree of dilution by recycling the diluted concentrate fluid in a first recycling fluid path comprising the container and the draw side of the FO unit until one or more predetermined criteria are met.

[0029] According to another aspect, which can be combined with any other aspect or part of the present disclosure, the method comprises controlling the degree of dilution by recycling water in a second recycling fluid path comprising the feed side of the FO unit until one or more predetermined criteria are met.

[0030] According to another aspect, which can be combined with any other aspect or part of the present disclosure, the method comprises directing the used water downstream of the FO unit to a water container.

[0031] According to another aspect, which can be combined with any other aspect or part of the present disclosure, the method comprises supplying the osmotic agent from an osmotic agent source to the fluid path to achieve a prescribed concentration of the osmotic agent in the diluted PD concentrate fluid.

[0032] According to another aspect, which can be combined with any other aspect or part of the present disclosure, the method comprises directing the effluent from an effluent source to the feed side of the FO unit to transport water from the effluent to the one or more PD concentrate fluids through the FO membrane by means of the osmotic pressure gradient between the draw side and the feed side. Thus, the one or more PD concentrate fluids are diluted to produce a pre-diluted PD concentrate fluid, wherein the pre-diluted concentrate is comprised in the one or more PD concentrate fluids that the FO unit is configured to receive.

[0033] According to another aspect, which can be combined with any other aspect or part of the present disclosure, the method comprises pre-treating the water received via the water connector before the water received via the water connector is passed to the FO unit.

[0034] According to another aspect combinable with any other aspect or portion of the present disclosure, the method includes directing the diluted PD concentrate fluid to an outlet container upon satisfaction of one or more predetermined criteria.

[0035] According to another aspect combinable with any other aspect or portion of the present disclosure, one of the one or more sources of PD concentrate includes a fluid including one or more of lactate, acetate, citrate, bicarbonate, NaCl, MgCh, CaCh, and KC1.

[0036] According to yet another aspect combinable with any other aspect or portion of the present disclosure, the present disclosure relates to a computer program comprising instructions to cause a system according to any system aspect to perform the steps of a method according to any method aspect.

[0037] According to yet another aspect combinable with any other aspect or portion of the present disclosure, the present disclosure relates to a computer readable memory having stored thereon a computer program of the computer aspect.

[0038] Additional features and advantages are described in, and will be apparent from, the following DETAILED DESCRIPTION and the Figures. The features and advantages described herein are not all-inclusive and are BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 and Figures 4 to 9 A system for producing fluid for PD according to some embodiments is shown.

[0040] Figure 2 and Figure 3 is a flowchart showing a method for producing fluid for PD according to some embodiments. DETAILED DESCRIPTION

[0041] In the following disclosure, several embodiments of systems and methods for producing fluid for PD are described. The embodiments each utilize a forward osmosis (FO) unit to dilute one or more PD concentrate using purified water transported from water through the FO membrane. The water becomes purified as it is transported through the FO membrane and directly dilutes the PD concentrate on the other side of the FO membrane into a diluted PD concentrate fluid. The diluted PD concentrate can be recirculated until it pulls enough water through the FO membrane to achieve a desired dilution. The diluted PD concentrate can have the prescribed composition of the final PD fluid after the FO session, or can need to be mixed with additional PD concentrate (e.g., PD fluid including an osmotic agent) before it has the prescribed composition of the PD fluid. The PD fluid can be defined as the PD fluid ready to be used by a patient in a PD treatment. The system can be used for different variants of automated PD, including online mixing of the PD fluid and batch mixing of the PD fluid. The water can be pretreated before being used in the FO unit 6.

[0042] The water used in the FO unit can be raw water (e.g., tap water) or pretreated raw water. The system described herein can include a pretreatment module arranged to treat the raw water before it is provided to the FO unit.

[0043] In the following, reference is made to Figure 1 A system for producing fluid for PD is described. The same reference signs in all the figures will generally not be repeated. The system 1 includes a fluid path 2, a plurality of connectors, and a forward osmosis (FO) unit 6. The fluid path 2 can be enclosed within a housing (not shown) in Figure 1 The fluid path 2 can be part of a device. The fluid path 2 includes a plurality of fluid lines. These fluid lines can be the plurality or all fluid lines as described herein. The connectors include one or more PD concentrate connectors 3a, 3b. Each PD concentrate connector 3a, 3b is configured to be connected to a source 4a, 4b of PD concentrate fluid. The source of PD concentrate fluid is typically a bag filled with PD concentrate. Each PD concentrate connector 3a, 3b is then configured to be connected to a corresponding connector of a bag provided with PD concentrate fluid. The connectors further include a water connector 7a. The water connector 7a can be a water port. The water connector 7a is typically configured to be connected to a source of raw water, e.g., a hose connected to a water tap. The raw water can thus be tap water. The water can be pretreated before it is supplied to the FO unit 6.

[0044] The system 1 can further include a pretreatment unit 8 Figures 4 to 8), the pre-treatment unit is configured to pre-treat water received via the water connector 7a before it is passed to the FO unit 6. The FO unit 6 comprises a draw side 6a and a feed side 6b separated by a FO membrane 6c. The FO membrane 6c typically has a pore size in the nanometer (nm) range, e.g. from 0.5 to 5 nm or less, depending on the solutes intended to be blocked. The FO unit 6 is fluidly connected to the fluid path 2. The FO unit 6 is configured to receive the one or more PD concentrate fluids 4a, 4b at the draw side 6a and the (pre-treated) water at the feed side 6b to transport purified water from the water to the one or more PD concentrate fluids through the FO membrane 6c by means of an osmotic pressure gradient between the draw side 6a and the feed side 6b. Thus, the one or more PD concentrate fluids are diluted into diluted PD concentrate fluids. Suitable FO units for the FO unit 6 are available from Aquaporin TM , Asahi KASEI TM , Berghof TM , CSM TM , FTSH2O TM , Koch Membrane Systems TM , Porifera TM , Toyobo TM and Toray TM .

[0045] The FO membrane 6c can be a water permeable membrane that separates water (feed side) and PD concentrate (draw side). The fluids in the different sides 6a, 6b can flow counter-currently or co-currently. The water can flow single pass, thus, the used water can be passed to the drain after having passed the feed side 6b once. Likewise, the FO membrane 6c can have a pore size in the nanometer (nm) range, e.g., from 0.5 to 5 nm or less, depending on the solutes intended to be blocked. The FO membrane 6c is typically designed to be more or less exclusively selective for water molecules, which enables the membrane to separate water from all other contaminants, thus being further purified. The geometry of the membrane can be flat fiber, tubular fiber or hollow fiber. Alternatively, the water can be recirculated one or more times to the feed side 6b and / or the draw side fluid can be recirculated one or more times to the draw side 6a. The purified water from the water is transported through the FO membrane 6c by means of the driving force created by the osmotic pressure difference between the water (feed solution) and the one or more PD concentrate fluids (draw solution). This means that the water will become more concentrated throughout the FO process. On the other hand, the one or more PD concentrate liquids will become more and more diluted throughout the FO process. The FO membrane 6c can be a water treatment membrane capable of facilitating a forward osmosis process. It is a semipermeable membrane that allows water to flow from the low concentrate side (feed side) to the high concentrate side (draw side). The FO membrane typically comprises a thin rejection layer (or active layer) and an underlying porous support. The geometry of the membrane can be flat fiber, tubular fiber or hollow fiber.

[0046] In more detail, the first PD concentrate bag 4a is connected to the first PD concentrate connector 3a via a first bag connector (not shown). The first fluid line 21 is fluidly connected between the inlet port of the draw side 6a and the first PD concentrate connector 3a. Thus, the first fluid line 21 connects the first PD concentrate connector 3a and the draw side 6a. The second PD concentrate bag 4b is connected to the second PD concentrate connector 3b via a second bag connector (not shown). The fluid line 21a is fluidly connected between the second PD concentrate connector 3b and the first fluid line 21. Thus, the fluid line 21a connects the second PD concentrate connector 3b and the first fluid line 21. Thus, the fluid path 2 comprises the second PD concentrate connector 3b. The second PD concentrate connector 3b is configured to be connected to a fluid source containing an osmotic agent. Alternatively, the fluid line 21a can be connected to a second fluid line 22 to supply PD concentrate from the second PD fluid bag 4b to the diluted PD fluid.

[0047] The second fluid line 22 is fluidly connected between the outlet of the draw side 6a and an outlet connector 5a. The outlet connector 5a is for example an outlet port. Thus, the second fluid line 22 fluidly connects the draw side 6a and the outlet connector 5a. The outlet connector 5a is configured to be connected to a corresponding connector (not shown) of a fluid line 5 configured to directly deliver the final PD fluid to a catheter of a patient, to a cycler for pumping the fluid to a patient or to a batch container. The first pump 41 is configured to control the flow rate of the diluted PD concentrate fluid in the second fluid line 22. At the same time, the first pump 41 can control (if no pump 43 is provided) the flow rate of the PD concentrate fluid in the first fluid line 21. In some embodiments, a third pump 43 is arranged to control the flow rate of the one or more PD concentrate fluids in the first fluid line 21 and thus to the draw side 6a or to the container 9, if present. The container 9 is further explained below. The third fluid line 25 is connected between the water connector 7a and the inlet port of the feed side 6b. Thus, the third fluid line 25 fluidly connects the water connector 7a and the feed side 6b. The fourth fluid line 26 is connected between the outlet port of the feed side 6b and a drain connector 12a. Thus, the fourth fluid line 26 connects the feed side 6b and the drain connector 12a. The second pump 42 is arranged to control the flow rate of the used water from the feed side 6b. In the shown embodiment, the second pump 42 is arranged to operate with the fourth fluid line 26. The drain connector 12a is configured to be connected to a corresponding connector of a drain line (not shown) which can be connected to a drain to remove used water after use or to a bag or water container of used water. Thus, in some embodiments, the system 1 comprises a water container 12 configured to collect used water downstream of the FO unit 6. The used water can be used as a feed solution in an upcoming FO session (e.g. during a first part of the FO session) thereby reducing the amount of water used.

[0048] The concentration sensor 51 is arranged to sense the concentration of the fluid in the second fluid line 22. Hence, the concentration sensor 51 is positioned to sense the concentration of the diluted PD concentrate fluid. In some embodiments, the system 1 comprises a container 9. The container 9 is fluidly connected or connectable to the fluid path 2. The container 9 is arranged to contain the diluted PD concentrate fluid. The container 9 can also be used to collect one or more concentrates before they are supplied to the draw side 6a. A variant embodiment is to pre-fill one or more concentrates in the container 9 for mixing to form a batch, which can be a batch for the entire treatment. Additional concentrates can then be added after the dilution process. In embodiments comprising the container 9, the fifth fluid line 27 is fluidly connected between the second fluid line 22 downstream of the concentration sensor 41 and the container 9. Hence, the fifth fluid line 27 fluidly connects the second fluid 22 and the container 9. The sixth fluid line 23 is connected between the container 9 and the first fluid line 21. Hence, the sixth fluid line 23 fluidly connects the container 9 and the first fluid line 21. In the illustrated embodiment, the draw side 6a, a portion of the second fluid line 22, the fifth fluid line 27, the container 9, the sixth fluid line 23, and a portion of the first fluid line 21 form a first recirculation fluid path 61. Hence, the fluid path 2 comprises the first recirculation fluid path 61 comprising the draw side 6a of the FO unit 6 and the container 9. The control device 10 is configured to control the degree of dilution by recirculating the diluted concentrate fluid in the first recirculation fluid path 61 until one or more predetermined criteria are met.

[0049] The concentration sensor 51 is for example a conductivity sensor configured to sense the electrical conductivity of the fluid, or a resistivity sensor configured to sense the electrical resistivity of the fluid. If desired and as known in the art, the sensed value can be converted to a conductivity value even if a resistivity sensor is used, for example. The conductivity can likewise be converted to a resistivity.

[0050] In some embodiments, the system 1 comprises a seventh fluid line 19 arranged between the third fluid line 25 and the fourth fluid line 26. Thus, the seventh fluid line 19 connects the third fluid line 25 and the fourth fluid line 26. The second recirculation fluid path 62 comprises the feed side 6b, a portion of the third fluid line 25, the seventh fluid line 19, and a portion of the fourth fluid line 26. Thus, in the illustrated embodiment, the fluid path 2 forms the second recirculation fluid path 62 comprising the feed side 6b of the FO unit 6a. The control device 10 is configured to recirculate water in the second recirculation fluid path 62 until one or more predetermined criteria are met. The water to be recirculated can be collected in an additional container (not shown) and the water to and from the additional container and the second recirculation path 62 can be passed via one or both ports in the additional container. An additional valve (not shown) can be arranged to control the flow of water to and from the additional container.

[0051] In some embodiments, the effluent (i.e. used PD fluid from a patient) is used as the feed solution before water is used as the feed solution. The FO unit 6 is then configured to receive the effluent at the feed side 6b. Water is transported from the effluent to the one or more PD concentrate fluids through the FO membrane 6 by means of the osmotic pressure gradient between the draw side 6a and the feed side 6b, thereby diluting the one or more PD concentrate fluids to produce pre-diluted PD concentrate fluids. The pre-diluted PD concentrate fluids are collected in the container 9. The pre-diluted concentrate fluids are then one of the one or more PD concentrate fluids that the FO unit 6 is configured to receive. Thus, the one or more PD concentrates can be pre-diluted with water drawn from the effluent via FO before being further diluted with purified water from raw water or pre-treated water. Thus, additional water is saved. In such embodiments, the fluid path 2 can comprise an inlet connector 29a. An eighth fluid line 29 is connected between the inlet connector 29a and the third fluid line 25. The eighth fluid line 29 fluidly connects the inlet connector 29a and the third fluid line 25. The inlet connector 29a is connected to a corresponding connector (not shown) of a source 30a of effluent attached to the inlet connector 29a. The source 30a of effluent can be an effluent container or bag having effluent from a previous discharge of effluent from a PD patient. Thus, in some embodiments, the fluid path 2 comprises an inlet connector 29a configured to be connected to a source 30a of effluent (e.g. an effluent container). In some embodiments, the system comprises an effluent container fluidly connected or connectable to the fluid path 2. The effluent container is arranged to contain effluent from a patient.

[0052] The system 1 further comprises a control device 10. The control device 10 comprises a control unit 40 comprising a processor and a memory. The memory typically stores a program which, when executed by the processor, controls the system 1. The control unit 40 can further comprise a communication interface which enables the control unit 40 to communicate data and signals to and can communicate data and signals from components of the system 1, e.g. sending control signals to valves and pumps, and receiving sensed data from concentration sensors and feedback signals from valves and pumps. The control device 10 can further comprise any one or more of the pumps 41, 42, 43 as shown. The control device 10 can further comprise valves which, for ease of illustration, are not included in Figure 1 The valves as described herein are typically on / off valves and can be two-way valves or three-way valves.

[0053] In some embodiments, the control device 10 is configured to control the degree of dilution of the one or more PD concentrate liquids during the production of the diluted PD concentrate fluid based on the sensed concentration of the diluted PD fluid such that one or more predetermined criteria are met. Different criteria can be used depending on the current stage in the production of the PD fluid, which will be explained in more detail below. In some embodiments, the control device 10 is configured to control the degree of dilution of the one or more PD concentrate liquids by controlling the flow rate of the one or more PD concentrate fluids to the inlet of the draw side 6a, and / or controlling the flow rate of water to the inlet of the feed side 6b, and / or controlling the flow rate of waste water from the outlet of the feed side 6b. The flow rate of the one or more PD concentrate fluids to the inlet of the draw side 6a can be controlled with the first pump 41. The flow rate of water to the inlet of the feed side 6b can be controlled with the second pump 42. For example, any one or more of the pumps 41-43 and any other pump described herein are volumetric pumps, e.g. piston pumps or diaphragm pumps. Alternatively, any one or more of the pumps 41-43 and any other pump described herein can be flow pumps used with a flow meter or a weigh scale.

[0054] In some embodiments, only one first kind of PD concentrate liquid is used as draw solution. The PD concentrate liquid then comprises e.g. a buffer. Then another second kind of PD concentrate liquid can be supplied to the diluted PD concentrate fluid after the FO phase. The other second kind of PD concentrate liquid comprises e.g. an osmotic agent. The other second kind of PD concentrate liquid is e.g. glucose. Alternatively, the other second kind of PD concentrate liquid is used as draw solution together with the first kind of PD concentrate liquid. Thus, the control device 10 is configured to supply the osmotic agent from the osmotic agent source 4b to the fluid path 2 to achieve a prescribed concentration of the osmotic agent in the diluted PD concentrate fluid.

[0055] The diluted PD concentrate can be recirculated in the first recirculation fluid path 61 until the sensed concentration meets one or more criteria for the final PD fluid. Typically, the sensed concentration should be within a certain interval. When this is achieved, the control device 10 is configured to direct the diluted PD concentrate fluid to the outlet connector 5a. Another criterion is that the PD fluid is ready and has a certain time to expire, for example.

[0056] The final PD fluid has a composition of the PD concentrate and water that achieves a prescribed or predetermined composition. Thus, it is also known that the final PD fluid should have a prescribed concentration of one or more PD concentrates, for example, 1.36%, 2.27% or 3.86% glucose. The final PD fluid is the PD fluid ready to be delivered to the peritoneal cavity of a patient. The production rate can be batch-wise, i.e. a certain volume of final PD fluid should be produced. The certain volume is then a batch. Alternatively, the production of final PD fluid is continuous, which is delivered until the control device 10 determines that the delivery should be stopped.

[0057] One of the one or more PD concentrate sources 4a can comprise a fluid comprising one or more of: lactate, acetate, citrate, bicarbonate, KCI, MgCh, CaCh and NaCI. For example, the PD concentrate source comprises a fluid comprising a buffer, for example, one or more of: lactate, citrate, acetate and bicarbonate. The fluid, when diluted with water and possibly other PD concentrates, becomes a final PD fluid having a pH suitable for PD treatment and being one or more of: KCI, MgCh, CaCh, NaCI.

[0058] Figure 2 is a flow chart of a method for producing a pre-diluted PD fluid by means of an effluent and one or more PD concentrates according to some embodiments. Figure 3 is a flow chart of a method for producing a fluid for PD according to some embodiments described herein. The methods can be implemented as instructions on a computer program and saved in the memory of the control unit 40. The methods are explained with reference to Figure 2 and Figure 3 the flow Figure 1 charts of Figs. 1-3. Blocks shown in dashed lines correspond to alternative or optional functions or procedures.

[0059] Reference is made to Figure 2At S1a, the method includes directing the effluent from the source 30a of effluent to the feed side 6b of the FO unit 6a. At S1b, the method also includes directing one or more PD concentrate fluids into the draw side 6a. Water from the effluent is then transported through the FO membrane 6 by means of an osmotic pressure gradient between the draw side 6a and the feed side 6b to the one or more PD concentrate fluids, thereby diluting the one or more PD concentrate fluids and producing a pre-diluted PD concentrate fluid. Thereafter, the pre-diluted concentrate fluid is included in the one or more PD concentrate fluids that the FO unit 6 is configured to receive. In one embodiment, the one or more PD concentrate fluids used as draw solutions include PD concentrate fluids that include one or more buffers.

[0060] At S1c, the method also includes sensing the concentration of the diluted PD concentrate fluid, for example, with the concentration sensor 51. The method also includes directing the diluted PD concentrate fluid into the container 9 at S1d. Thus, the PD concentrate fluid can be pre-diluted using effluent from a previous discharge of the patient.

[0061] Reference is made to the flowchart in Figure 3 for explaining a method for producing fluid for PD. As described in the flowchart of Figure 2 , the method can be performed prior to the method described in Figure 3 . The method can be performed using any of the systems 1 described herein. Prior to the method commencing, the system 1 is connected to a source of water 7, for example, to a water tap via a hose, to the water connector 7a. The discharge connector 12a is connected to a discharge or to a discharge bag for collecting used water. The outlet connector 5a is connected to a fluid line 5. A dedicated bag with PD concentrate fluid is connected to the PD concentrate fluid connectors 3a, 3b. The water can be directly from a water tap, considered as “raw water”. The method can then pre-treat the raw water prior to further use thereof. In other words, at S2, the method includes pre-treating the water received via the water connector 7a prior to passing it to the FO unit 6. Alternatively, the water is already pre-treated and can thus be supplied directly to the FO unit 6. The pre-treatment can include, for example, removing large particles using a sediment filter, and / or removing chlorine and variants thereof (e.g., chloramine, etc.) using a mixed bed. In any case, at S3, the method includes directing the (pre-treated) water into the feed side 6b of the FO unit 6. The water is directed to the feed side using, for example, a valve (not shown in Figure 1 ). The water is pumped to and through the feed side 6b using the second pump 42. Simultaneously, at S4, the method includes directing one or more PD concentrate fluids into the draw side 6a of the FO unit 6.

[0062] In one embodiment, a PD concentrate fluid with one or more buffers is used as the draw solution. This PD concentrate fluid can be provided in the first PD concentrate bag 4a. The PD concentrate fluid with one or more buffers is then directed into the draw side 6a (e.g., using a valve, Figure 1 the first pump 41. Alternatively, the draw solution is a mixture of two different PD concentrate fluids. In an example, the first PD concentrate bag 4a provides a fluid with one or more buffers and / or electrolytes, while the second PD concentrate bag 4b provides a solution with one or more osmotic agents. The draw solution is then a mixture of the fluids from the first and second bags 4a, 4b. These fluids are then directed and pumped to the container 9, which is then used as the draw solution in the FO unit 6. Yet alternatively, the draw solution is one or more PD concentrates that have been pre-diluted using outflow from the patient. In any case, the method includes directing one or more PD concentrates into the draw side 6a of the FO unit 6. The FO unit 6 produces a diluted PD concentrate.

[0063] At S5, the method senses a concentration of the diluted PD concentrate fluid. For example, the sensed concentration determines when the PD concentrate is sufficiently diluted, when the diluted PD concentrate fluid is properly mixed, or when a final PD solution is produced. In some embodiments, at S6, the method includes directing the diluted PD concentrate fluid into the container 9. The method can include recirculating the diluted PD concentrate in a first recirculation fluid path 61 that includes the container 9 until the concentration has reached a concentration that satisfies a concentration of one or more PD concentrates of a final PD fluid. That is, at S7, the method can include controlling a degree of dilution by recirculating the diluted concentrate in the first recirculation fluid path 61 that includes the draw side 6a of the FO unit 6 and the container 9 until one or more predetermined criteria are satisfied. During recirculation, the diluted PD concentrate continues to draw water from the feed solution and becomes more and more diluted. The recirculation continues until one or more criteria are satisfied. When, at S7c, the concentration of the diluted PD concentrate satisfies one or more criteria, the method can include collecting the diluted PD concentrate in the container 9 or directing the diluted PD concentrate fluid to the outlet connector 5a at S12.

[0064] If only a solution with a buffer and / or one or more electrolyte agents is used as the draw solution, at S10 the method comprises supplying a PD concentrate fluid comprising one or more osmotic agents to the diluted PD concentrate solution. A predetermined amount of PD concentrate fluid comprising one or more osmotic agents can be supplied from the second concentrate bag 3b into the reservoir 9 or from an osmotic agent source into the fluid path 2, for example into the second fluid line 22, to achieve a prescribed concentration of osmotic agents in the diluted PD concentrate fluid. Thereafter, the method can comprise directing the diluted PD concentrate fluid to the outlet connector 5a. If the PD concentrate fluid comprising one or more osmotic agents has been used as the draw solution together with the PD concentrate fluid with one or more buffer agents, the method can comprise directing the diluted PD fluid to the outlet connector 5a without directing the diluted PD fluid via the reservoir 9. In other words, if the concentration of the diluted PD concentrate fluid corresponds to the final degree of dilution of the PD fluid, the method can comprise directing the diluted PD concentrate fluid to the outlet connector 5a. If not, at Sll the method can supply additional PD concentrate fluid from one or more PD concentrate sources 4a, 4b to complete the composition of the final PD fluid.

[0065] At S7a the method can control the degree of dilution of the one or more PD concentrate fluids by controlling the flow rate of the one or more PD concentrate fluids to the inlet of the draw side 6a and / or at S7b by controlling the flow rate of water at the inlet of the feed side 6b. The flow rate of the one or more PD concentrate fluids to the inlet of the draw side 6a is controlled, either with the third pump 43 or with the first pump 41. The outflow rate of water from the feed side 6b is typically controlled with the second pump 42. Alternatively, the flow rate of water into the feed side 6b is controlled, in which case the second pump 42 can be arranged to the third fluid line 25. The amount of PD concentrate in the desired composition PD fluid and the concentration of the one or more PD concentrates are known in advance. Thus, for each batch of final PD fluid, the amount of one or more PD concentrates to be supplied into the draw side 6a is known. If the diluted PD fluid is not recirculated, the one or more PD concentrate fluids need to draw the necessary water in a single pass to dilute the one or more PD concentrates to the final degree of dilution corresponding to the prescribed degree of dilution of the PD fluid. The sensed concentration will then be used as a feedback for the first pump 41 (as Figure 1feedback of the first (and optionally the second) pump 42 to adjust the speed of the pump(s) so that the concentration meets one or more criteria for the final PD fluid. If PD concentrate fluid including one or more osmotic agents is supplied to the diluted PD concentrate fluid after the FO session, the criteria is that the concentration of the diluted PD concentrate fluid is equal to or close to a concentration that matches a prescribed concentration of the diluted PD fluid in the final PD fluid. The target concentration of the PD concentrate fluid from the first PD concentrate fluid bag 4a (in the final PD fluid) can be a function of the target concentration of the PD concentrate fluid from the second PD concentrate fluid bag 4b (in the final PD fluid). After the PD concentrate fluid including one or more osmotic agents has been supplied to the diluted PD concentrate fluid, the method can include directing the diluted PD fluid (now including one or more osmotic agents) through the draw side 6a, or into a bypass line that bypasses the draw side 6a, or into a mixing chamber (not shown) to ensure homogeneity of the solution, thereby ensuring a homogeneous solution. The method can ensure homogeneity by sensing the concentration and monitoring that the concentration of the diluted PD concentrate fluid is within a concentration interval for a certain period of time. Thus, the diluted PD concentrate fluid is now a ready PD fluid.

[0066] The used water in FO can become richer, and thus more concentrated. The method can include directing the used water to a drain, recirculating the used water for reuse, or at S8, directing the used water downstream of the FO unit 6 to the water container 12, or a combination thereof. Thus, water can be used in a single pass, so that fresh water is always used in FO. Alternatively, a predetermined amount of water is used and recirculated, drained directly after FO is completed or collected in the water container, and thus available for an upcoming FO session. In yet another embodiment, a major portion of the used water is recirculated, some of the used water is directed to a drain, and some fresh water is introduced. Thus, in some embodiments, at S7, the method includes controlling the degree of dilution by recirculating water in a second recirculation fluid path 62 including the feed side 6b of the FO unit 6a until one or more predetermined criteria are met.

[0067] To provide a final PD fluid that can be introduced directly into the peritoneal cavity of a patient, the method can include heating the fluid in the fluid path 2 with a heater 52( Figures 4 to 8 ) The heater 52 can also be used to sterilize the fluid path 2 of the system 1.

[0068] Different APD systems 1 are now described that use FO to purify water and simultaneously dilute PD concentrate fluid. Figure 4 A system 1 with batch PD fluid production is shown. Figure 5 A system 1 with continuous PD fluid production is shown. Figure 4The same system, with the added ability to use the effluent as a feed solution to pre-dilute the PD concentrate. Figure 6 System 1 is shown, in which PD concentrate from both a first PD concentrate bag 4a and a second PD concentrate bag 4b can be introduced into a second fluid line 22, allowing one or more PD concentrate fluids to be pumped to container 9 using a first pump 41. Identical reference numerals throughout the figures may not be repeated in the text, but include all structures, functions, and alternatives already described in conjunction with reference numerals.

[0069] Figure 4 System 1 is explained together with the recommended order of production of the fluids used for PD (including diluted PD concentrate and final PD fluid). For... Figure 1 The system contains the same components, and system 1 has the same reference numerals. Furthermore, the system includes a third pump 43 (in...). Figure 1 (Shown in dashed lines) The third pump 43 is configured to control the flow rate of one or more PD concentrated fluids in the first fluid line 21. The first fluid line 21 is also provided with a first valve 31, which is arranged to operate together with the first fluid line 21 upstream of the connection point between fluid line 21a and the first fluid line 21. A second valve 32 is arranged to operate together with the fluid line 21 upstream of the same connection point between fluid line 21a and the first fluid line 21. The third pump 43 is arranged to operate together with the first fluid line 21 downstream of the same connection point. The third valve 33 is arranged to operate together with a sixth fluid line 23. The sixth fluid line 23 is arranged between the first port 9a of the container 9 and the first fluid line 21. A fourth valve 34 is arranged to operate together with a third fluid line 25 downstream of the pretreatment unit 8, and is arranged between the pretreatment unit 8 and the inlet of the feed side 6b. A fifth valve 35 is disposed on a seventh fluid line 19 between the connection point to the third fluid line 25 and the connection point to the fourth fluid line 26. A tenth fluid line 18 is disposed between the seventh fluid line 19 and the second fluid line 22. A sixth valve 36 is disposed to operate in conjunction with the tenth fluid line 18. A seventh valve 37 is disposed to operate in conjunction with the second fluid line 22 near the outlet connector 5a. An eighth valve 38 is disposed to operate in conjunction with the pressure relief line 28 from the container 9. A ninth valve 39 is disposed to operate in conjunction with the seventh fluid line 19 downstream of the connection point to the fourth fluid line 26 and the tenth fluid line 18. The ninth valve 39 controls the flow to the discharge connector 12a.

[0070] A fifth fluid line 27 is fluidly connected to the second fluid line 22 and the second port 9b of the container 9. Thus, the fifth fluid line 27 connects the second fluid line 22 and the second port 9b of the container 9. The tenth valve 44 is arranged to operate with the second fluid line 22 between the connection point to the tenth fluid line 18 and the connection point to the fifth fluid line 27. The first pump 41 is arranged to operate with the fifth fluid line 27, instead of with the second fluid line 22 in the system of Figure 1

[0071] The first pressure sensor 54 is arranged to sense the pressure in the fifth fluid line 27 between the first pump 41 and the container 9. The second pressure sensor 55 is arranged to sense the pressure in the second fluid line 22, which is the pressure of the final PD fluid supplied to the outlet connector 5a. The liquid level sensing device 11 is arranged to sense the fluid level in the container 9. For example, the liquid level sensing device 11 comprises an analog liquid level sensor. The control device 10 is configured to control the diluted PD concentrate fluid in the first recirculation fluid path until the volume of the diluted PD concentrate fluid meets a volume criterion. The volume of the diluted PD concentrate fluid can be sensed with the liquid level sensor or determined by means of the number of pump strokes performed with the volumetric first pump 41. An ultraviolet (UV) lamp 57 can be arranged inside the container 9 to disinfect the container 9. A water conductivity sensor 56 is arranged to sense the conductivity of the water downstream of the pre-treatment unit 8.

[0072] The suggested order of use of the system 1 in Figure 4 comprises one or more of the following steps:

[0073] 1. Start tap water pre-treatment. The water connector 7a is connected to a tap water source, e.g. via a hose. During this step, the valves 31, 32, 33, 34, 36, 37, 38 and 44 are closed, while the valves 35 and 39 are open. The water is then pre-treated in the pre-treatment unit 8, and the conductivity is sensed with the water conductivity sensor 56.

[0074] ​2. The entire batch volume of PD concentrate fluid from the first PD concentrate bag 4a is dosed by volume to the container 9. During this step, valves 32, 34, 35, 36, 37, 39, 44 are closed, while valves 31, 33, 38 are open. The third pump 43 pumps PD concentrate from the first PD concentrate bag 4a. The level sensing device 11 senses the level in the container 9.

[0075] 3. The entire batch volume of PD concentrate fluid from the second PD concentrate bag 4b is dosed by volume to the container 9. During this step, valves 31, 34, 35, 36, 37, 39, 44 are closed, while valves 32, 33, 38 are open. The third pump 43 pumps PD concentrate from the second PD concentrate bag 4b. The level sensing device 11 senses the level in the container 9.

[0076] 4. The FO filter is primed with water, including pumping pretreated tap water through the FO filter. During this step, valves 31, 32, 33, 35, 36, 37, 38, and 44 are closed, while valves 34 and 39 are open. Water is pretreated in the pretreatment unit 8, the conductivity is sensed with the water conductivity sensor 8, and the pretreated water is pumped through the feed side 6b and out through the drain connector 12a with the second pump 42.

[0077] 5. FO / Mixing period. Pretreated tap water is pumped through the FO unit 6. The flow rate pumped with the second pump 42 will be the reject flow passed to the drain connector 12a. The first pump 41 is running forward to recirculate the fluid in the container 9 first through the FO unit 6, through the third valve 33, and then back to the container 9. The level sensing device 11 and the conductivity sensor 51 monitor the FO period (including mixing) with respect to the volume and composition of the PD fluid that is changing. The FO period continues until the target concentration (e.g., target conductivity) is reached. The target concentration of the diluted PD concentrate from the first PD concentrate bag 4a is calculated based on the target osmotic agent concentration in the final PD fluid. During this period, valves 31, 32, 35, 36, and 37 are closed, while valves 33, 34, 38, 39, and 44 are open. Water is pretreated in the pretreatment unit 8, the conductivity of the pretreated water is sensed with the water conductivity sensor 56, the second pump 42 provides the flow of water into the feed side 6b, the first pump 41 provides the flow rate into the draw side 6a, the level sensing device 11 senses the level in the container 9, and the conductivity sensor 51 senses the conductivity. 6.

[0079] a. Transmembrane pressure relief. Due to the remaining concentration gradient between the water side (feed side 6b) and the PD fluid side (extraction side 6a) of FO unit 6, significant transmembrane pressure could build up if the two sides were kept rigidly separated. This pressure could damage FO unit 6 or the fluid path around it. By opening the extraction side 6a for venting and opening the feed side for pretreatment, the concentration difference between the feed and extraction sides is sufficiently uniform to allow near-emptying without the risk of building up excessive transmembrane pressure. During this step, valves 31, 32, 33, 35, 37, and 38 are closed, while valves 34, 36, 39, and 44 are open.

[0080] b. as Figure 6 An alternative to method a is to slow down the water extraction process by introducing a diluted concentrate to the feed side of the FO unit to increase its concentration, thereby achieving transmembrane depressurization. This serves two purposes: the dilution process is slowed down and can be better controlled to achieve the target dilution while maintaining recirculation and preventing transmembrane pressure buildup as the water extraction process eventually stops. Introducing the diluted concentrate to the feed side can be performed by pump 41 via valves 34, 35, 36 and / or by expanding the FO volume of the extraction volume retained between valves 33 and 34. Alternatively, effluent can be introduced for the same purpose. Figure 5 Fine-tuning of water extraction can be achieved by controlling the amount of diluted concentrate, effluent, and pretreated water on the feed side.

[0081] 7. Transferring PD fluid. Once the desired concentration has been reached, the PD concentrate has been diluted to a concentration similar to that of the final PD fluid. During this step, valves 31, 32, 33, 34, 35, 36, 39, and 44 are closed, while valves 37 and 38 are open. The first pump 41 supplies flow of PD fluid from container 9 to outlet connector 5a, and the pressure is sensed using the second pressure sensor 55.

[0082] 8. Drain FO unit 6. Draining FO unit 6 into container 9 can be performed by pumping the first pump 41 in the opposite direction. In this step, valves 31, 32, 34, 35, 36, 37, 38, and 39 are closed, while valves 33 and 44 are open. The first pump 41 and the first pressure sensor 54 are operable. Alternatively, step 8 can be performed before step 7 to also transfer PD fluid volume on the extraction side. Typically, it is not required that these steps be performed in the listed order.

[0083] 9. Empty container 9. Container 9 can be emptied by running the first pump 41 in the forward direction. During this step, valves 31, 32, 33, 34, 35 and 37 are closed, while valves 36, 38, 39 and 44 are open.

[0084] 10. Repeat steps 2 to 9 at least once.

[0085] The proposed system 1 can be used to provide PD fluid to a patient, a PD cycler or a PD fluid container. The heater 52 can be used to heat sterilize the system 1 including the FO unit 6 and the FO membrane 6c. This enables re-use of the FO membrane 6c.

[0086] Figure 5 The system 1 as in Figure 4 is shown, in addition, it comprises an eighth fluid line 29 connected between the inlet connector 29a and the third fluid line 25, between the inlet port of the feed side 6a and the fourth valve 34. Thus, the eighth fluid line 29 fluidly connects the inlet connector 29a and the inlet port of the feed side 6a. An effluent line can be connected to the inlet connector 29a and arranged to pass effluent from a patient into the inlet connector 29a. The effluent can then be used as a feed solution as previously described in relation to the flow chart in Figure 2 . Water is then extracted from the effluent as a first step performed to pre-dilute the PD concentrate as much as possible. The raw water FO can be used to continue dilution until the PD fluid composition is reached.

[0087] Figure 6 The system 1 is shown with an alternative arrangement of the first fluid line 21 and the fluid line 21a. In this embodiment, the first fluid line 21 is also connected to the connection point between the second fluid line 22 and the fifth fluid line 27. The fluid line 21a is connected to the same connection point between the second fluid line 22 and the fifth fluid line 27. One or more PD concentrate can then be supplied to the container 9 by operating the first pump 41 in reverse. The one or more PD concentrate is then used as a draw solution by operating the first pump 41 in a forward direction as previously explained. In some embodiments, the PD concentrate fluid from the first fluid bag 4a is supplied to the container 9 by operating the first pump in reverse. The PD concentrate fluid from the first fluid bag 4a is then used as a draw solution and becomes diluted. The diluted PD concentrate fluid can be collected into the container 9 when a predetermined concentration is reached. Thereafter, the first pump 41 can supply a predetermined amount of PD concentrate from the second fluid bag 4b by operating the first pump 41 in reverse. The fluid in the container 9 can now be mixed by recirculating the fluid in the first recirculation fluid path 61 until a mixing criterion is met. The mixing criterion can comprise that the concentration has a value within a predetermined interval for a certain time. Alternatively, a mixing chamber (not shown) is fluidly arranged to the second fluid line 22 between the fifth fluid line 27 and the outlet connector 5a. The fluid can then be mixed in the mixing chamber on its way to the outlet connector 5a.

[0088] The suggested order described above produces PD fluid in batches. System 1 can also be used to produce PD fluid online using one or more PD concentrates and FO purified water. The basic principle of diluting a PD concentrate to nominal PD fluid composition is the same as the suggested order, but the control mechanism for producing PD fluid is different. Instead of recycling batches of varying diluted PD concentrate fluid until enough pure water has been extracted from the water at the feed side, the correct amount of water extraction (concentration dilution) is achieved during a single pass of one or more PD concentrates through FO unit 6. This can be achieved if one or more parameters that control the water extraction rate are controlled. These parameters include, but are not limited to:

[0089] 1. The pressure difference between the feed side 6b and the draw side 6a of FO unit 6.

[0090] 2. Temperature representing the fluid temperature at the feed side 6b and / or the draw side 6a.

[0091] 3. Water side osmotic pressure (drain flow rate).

[0092] 4. PD concentrate flow rate.

[0093] If the production flow rate of PD fluid to outlet connector 5a is controlled, for example, by a user or pressure feedback, the PD concentrate flow rate will determine the production rate of PD fluid and therefore not be used for water extraction rate control. The feedback mechanism for controlling the water extraction rate influencing parameter can be, for example, concentration (conductivity). The above-mentioned parameters can also be used to control the water extraction rate for batch production of PD fluid.

[0094] Water extraction from raw water (e.g., tap water) can be performed until the osmotic pressure of the water reaches a point where the osmotic pressure between the feed side 6b and the draw side 6a approaches zero and it is no longer possible to extract further water. The drain flow is therefore minimized, which means that tap water consumption is minimized. This can be achieved in a number of ways. In one embodiment, online production of PD fluid is performed, where the feed solution and the draw solution are supplied in a counter-flow flowing manner in FO unit 6, while the flow rates of the draw solution and the feed solution are controlled to achieve PD fluid composition at the draw side outlet and PD concentrate osmotic pressure close to the feed side outlet.

[0095] In another embodiment, batch production of PD fluid is performed. Here, during a first batch, a fresh tap water volume is recirculated in the second recirculation fluid path 62, while a PD concentrate fluid volume is recirculated in the first recirculation fluid path 61 until the PD fluid composition is reached at the draw side 6a. If the initial tap water volume is optimized, its osmotic pressure at the end of the batch production can be maximized (to approach the osmotic pressure of the PD fluid at the draw side 6a). During the second batch and upcoming batches, the remaining water volume (approaching the PD fluid osmotic pressure) can be reused for water extraction during the initial phase of the second batch production, since the draw solution is highly concentrated. This can even increase the osmotic pressure of the water before it is drained. Then, an optimized volume of fresh tap water is introduced and recirculated to complete the batch production. Thus, water consumption can be minimized by maximizing the waste water osmotic pressure. Depending on the characteristics of the FO membrane, the acceptable waste water osmotic pressure can be limited by water side fouling and / or forward flux of compounds accumulated at the water side. Recirculating water at the feed side has the potential advantage of reducing the risk of fouling due to increased total flow along the membrane.

[0096] Figure 7 and Figure 8 System 1 shows an alternative embodiment, which is an online embodiment producing a final PD fluid that is directly delivered to a patient or used for collection in a storage container for later use. In Figure 7 and Figure 8 The fluids are not mixed in the container 9 as done in Figure 1 (as an alternative) and Figures 4 to 6 Figure 7 and Figure 8 include many of the same components, including a first PD concentrate fluid 4a (e.g., a buffer concentrate) and a second PD concentrate fluid 4b (e.g., an osmotic agent or glucose concentrate) connected to the system 1 via PD concentrate connectors 3a and 3b, respectively. In Figure 7 and Figure 8 ​In FIG. 4, separate third or concentrate pumps 43a and 43b are provided for each PD concentrate fluid 4a, 4b. Also provided is a forward osmosis (FO) unit 6 including a draw side and a feed side. The feed side of the FO unit 6 is part of a feed side recirculation fluid path 62 that also includes a second or feed side pump 42 operable with the fourth fluid line 26 and valves 34 and 35. A concentration (e.g., conductivity) sensor 51, a temperature sensor 53, and a heater 52 are provided at the outlet of the draw side of the FO unit 6. The concentration (e.g., conductivity) sensor 51 and the temperature sensor 53 output to the control unit 40, which uses the conductivity reading as feedback while the control unit 40 causes one or more concentrates to be gradually added or diluted until a desired conductivity is reached. The control unit 40 uses the temperature reading as a compensation factor for the conductivity reading and as feedback for controlling the amount of power applied to the heater 52 to achieve a desired final PD fluid temperature (e.g., a body temperature of 37°C).

[0097] Figure 7 And Figure 8 An alternative embodiment of the system 1 in FIG. 4 also includes a pre-treatment unit 8 (which can include some or all of the structures, functions, and alternatives discussed herein) for pre-treating water entering the system 1 via the water connector 7a. Water exiting the pre-treatment unit 8 (i) flows via valves 35 and 39 to drain via the drain connector 12a or (ii) flows via valve 34 to the feed side of the FO unit 6. Figure 7 And Figure 8 The control device 10 in FIG. 4 is configured such that it can pull additional pre-treated water from the pre-treatment unit 8 into the feed side and / or pull one ( Figure 8 ) or two concentrates ( Figure 7 ) from the source 4a and / or 4b into the draw side, where the pre-treated water permeates across the FO membrane to dilute the one or more concentrates 4a and / or 4b. The FO membrane further filters and purifies the water, making it or ensuring it suitable for PD treatment.

[0098] Figure 7 And Figure 8 Also included are an outlet valve 37, an outlet connector 5a, and a pressure sensor 55 for controlling the patient pumping pressure. The pressure sensor 55 outputs to the control unit 40, which uses the pressure reading as feedback to control the speed of at least one of the pumps 42, 43a, and 43b to set the patient’s outlet pumping pressure at a safe level (e.g., 0.21 bar (3 psig) or less).

[0099] Figure 7 And Figure 8 The difference between the systems 1 of FIGS. 3 and 4 includes how the PD concentrate fluids 4a and 4b are introduced. In FIG. 3, the PD concentrate fluids 4a and 4b are introduced into the system 1 via the fourth fluid line 26. In FIG. 4, the PD concentrate fluids 4a and 4b are introduced into the system 1 via the first fluid line 21.Figure 7 In the first embodiment, both PD concentrate fluids 4a and 4b (e.g., buffer and dextrose) are pumped into the draw side 6a of the FO unit 6. Here, both of the diluted concentrate fluids are monitored by the concentration or conductivity sensor 51 for feedback to bring the final PD fluid to the desired concentration or conductivity. Parameters controlled via feedback from the concentration or conductivity sensor 51 include any one or more of the speeds of the concentration pumps 43a and 43b and the speed of the second or feed side water recirculation pump 42.

[0100] In the second embodiment, Figure 8 In the third embodiment, only the first PD concentrate fluid 4a (e.g., buffer) is pumped into the draw side of the FO unit 6, which is monitored by the concentration or conductivity sensor 51 for feedback to bring the PD fluid to the desired concentration or conductivity level of the first PD concentrate fluid (e.g., buffer). The second PD concentrate fluid 4b (e.g., dextrose) is pumped into the tenth fluid line 18 downstream of the FO unit 6. The second PD concentrate fluid 4b is mixed with the appropriately diluted first PD concentrate fluid 4a in the mixing chamber 60. The mixing chamber 60 can be a smaller vessel (e.g., 50 to 100 milliliters, smaller than the vessel 9) and operates with a pair of level sensors 60a and 60b outputting to the control unit 40, which uses the output to maintain the level of the PD fluid in the mixing chamber 60 somewhere between the sensors. The fluid also mixes in the tenth fluid line 18, so the mixing chamber can not be needed, e.g., as in the fourth embodiment discussed below. The mixing chamber 60 also serves as a gas separation chamber or gas trap, so can be provided in any of the embodiments of the system 1 discussed herein for further mixing and / or gas separation. Gas or PD fluid can be vented from the top of the mixing chamber 60 via the vent valve 64 to the drain connector 12a. Figure 7 In the third embodiment,

[0101] In the fourth embodiment, Figure 8 In the fourth embodiment, after the second PD concentrate fluid 4b is mixed with the diluted first PD concentrate fluid in the mixing chamber 60, the final PD fluid is pumped through the second or final concentration or conductivity sensor 71, which outputs to the control unit 40. The control unit 40 interrogates the output from the final conductivity sensor 71 to ensure that the final PD fluid has the desired final concentration or conductivity. If so, the control unit 40 causes the seventh or outlet valve 37 to open, allowing the appropriately mixed and heated final PD fluid to be pumped at a safe pumping pressure into the patient, cycler, or storage container or bag. If not, the control unit 40 causes the bypass valve 78 to open, allowing the inappropriately mixed PF fluid to be passed to the drain connector 12a.

[0102] As discussed above, the speed of at least one of the pumps 43a, 43b and 42 is controlled via the control unit 40 in order to deliver the final PD fluid to the patient at the desired concentration or conductivity (via feedback from the sensors 51 and possibly 71) and at the desired pressure (via feedback from the pressure sensor 55). Thus, each pump 43a, 43b and 42 (one or more pumps can run at a set speed) that is controlled via feedback has two feedback loops. To prevent the feedback loops from conflicting, the control unit 40 is envisioned to set maximum speeds to ensure that the patient pressure limits are not exceeded and to control the pumps within these maximum speeds to achieve the desired concentration or conductivity. That is, the feedback loop for concentration or conductivity is dependent on the feedback loop for pressure, as the pressure loop sets the speed limit within which the concentration or conductivity feedback loop can vary the speed of the concentration or conductivity control. This is true when the final PD fluid delivery flow is pressure controlled (e.g., when delivered directly to the patient). However, when delivered to a cycler or fluid container, a fixed delivery flow can be set, for example, then only the concentration feedback loop is active.

[0103] For any version of the system 1, the flow rates generated by the second or feed side pump 42 and the third or concentration pump 43 depend on the volume of water available and the time available for water extraction. Lower flow rates for these pumps increase the efficiency of extraction. The flow rates of the pumps 42 and 43 also depend on the size of the FO unit 6. A larger surface area of the unit increases the efficiency, which can allow for higher flow rates. Overall, what determines the efficiency is the combination of the raw water or effluent flow rate, the concentrate flow rate, and the membrane surface area.

[0104] In the example of the system 1, the effluent extraction and mixing takes 40 minutes, generating an effluent flow rate equal to or higher than 75 ml / min. Referring again to Figure 1 If, instead, a large volume of effluent (e.g., 8 to 10 liters) can be saved in the source 30a of effluent and 8 to 10 liters of diluted concentrate can be stored in the container 9, then a longer FO session would be allowed, generating an effluent flow rate of approximately 15 ml / min. This FO session can be performed during the treatment and within the day, without requiring other activities.

[0105] In the first stage, System 1 can extract water from the effluent in a very efficient manner (e.g., by reducing the effluent flow rate or increasing the transmembrane pressure (TMP)) to produce a diluted PD concentrate. In the second stage, System 1 can use a small amount, such as tap water, to further dilute the diluted concentrate into a final diluted concentrate. Thus, tap water consumption is minimized, and a permanent tap connection is not required. Instead, the patient can add a small amount (e.g., one liter per treatment) of tap water to a water tank (not shown) before treatment. The water tank then serves as the water source and is connected to the water connector 7a. The water extraction from the effluent performed in the first stage can be run on the volume of effluent from the previously discharged effluent during the current pause. Furthermore, if a large volume of effluent (e.g., 8 to 10 liters) can be stored in the effluent source 30a and 8 to 10 liters of diluted concentrate are stored in container 9, the efficiency of water extraction from the effluent (thus saving tap water) can be maximized, allowing for a longer FO period and producing an effluent flow rate of approximately 15 ml / min. This FO period can be performed during processing and during the day without any other activity.

[0106] It is also anticipated that, for any version of System 1 described herein, a transmembrane pressure gradient will be maintained between the feed side 6b and the extraction side 6a of FO unit 6, wherein the feed side pressure is greater than the extraction side pressure. This will improve the water extraction efficiency of FO unit 6. The transmembrane pressure gradient or ΔP anywhere may be higher than zero bar to four bar (58 psig) or higher, depending on the manufacturer's specifications and / or requirements for FO unit 6. One way to generate a higher feed side pressure is to... Figure 1 The second pump 42 moves to the third fluid line 25, so that the positive fluid pressure is applied to the feed side 6b of the FO unit 6. The speed of the second pump 42 is controlled to control the feed side pressure. Alternatively or additionally, a variable flow limiter (not shown) under the control of the control unit 40 can be added to operate with the fourth fluid line 26. Here, the control unit 40 causes the variable flow limiter to partially block the line 26, thereby creating an increased back pressure in the feed side of the FO unit 6. The second pump 42 and the flow limiter may be referred to herein as pressurizing devices. Alternatively or additionally, a pressure gradient can be induced by reducing the pressure on the extraction side 6a of the FO unit 6. It is anticipated that by constructing system 1 to reduce the extraction side pressure hydrostatically, the diluted PD concentrate container 9 will be in a lower position relative to the FO unit 6.

[0107] Alternatively or additionally, the extraction efficiency can be increased by heating or increasing the temperature of the FO unit 6. For example, if it is desired to have a higher FO unit 6 temperature, an additional or alternative heater (e.g., a pre-heater (not shown)) can be placed along the effluent fluid line 25 that heats or increases the temperature of the FO unit 6. For example, the increased effluent temperature anywhere can be from slightly above ambient temperature to 50°C or possibly higher, depending on the manufacturer of the FO unit. The temperature to which the effluent is heated is chosen so that the FO unit 6 in turn is heated to the desired level, and also so that the final PD fluid delivered to the patient can be set to about body temperature or 37°C. It can be found that the FO unit 6 acts as a heat sink, so that even if the effluent is heated to 50°C, the diluted concentrate exiting the FO unit 6 is below 50°C, and thus still requires heating via the downstream heater 14. In determining the temperature to which the effluent is heated, fouling in the effluent fluid line 25 is also a consideration, as higher temperatures can increase fouling. The reason for the increase in extraction efficiency that occurs by heating the FO unit 6 can be related to an increase in flux across the FO membrane 6c.

[0108] Thus, it is expressly contemplated that any version of the system 1 discussed herein manipulates, selects or sets any one or more of the membrane surface area, feed side and draw side flow rates, pressure gradient ΔP or transmembrane pressure across the membrane and / or the temperature of the FO unit 6 to achieve a desired exchange efficiency. These variables are balanced against cost and ease of use to produce an overall desirable system 1.

[0109] Referring now to Figure 9 , any version of the system 1 described herein can include structures to mitigate potential problems associated with controlling the dosing of concentrate. In particular, in Figure 1 , Figure 4 and Figure 5 , concentrate from the container 4b can enter the flow of concentrate from the container 4a, meaning that the two concentrates carry a small amount of the other concentrate when added (or at least in one dosing step). In addition, there will be air in the line 21 and / or line 21a when the first of either concentrate is added.

[0110] As a mitigation of the concentrate contamination problem, Figure 9Each concentrate line 21, 21a is directed towards a common point P where the lines 21, 21a meet the first recirculation fluid path 61. In this way, each concentrate 4a, 4b has its own route to the first recirculation fluid path 61, where the recirculation path is part of the mixing volume. Furthermore, the third or concentrate pump 43 is moved into the first recirculation fluid path 61, which allows the pump 43 to add the amount of concentrate that the control unit 40 has been programmed to add (without taking into account the stroke volume error of the pump) once the concentrate lines 21, 21a have been filled. Furthermore, the pump 43 is placed in parallel with a valve 45 under the control of the control unit via a circuit 46 extending to either side of the pump 43, so that the flow out of the FO unit 6 is free during the dilution phase, i.e. the valve 45 enables free flow through the recirculation fluid path 61. In one embodiment, the control unit 40 causes the pump 43 to run slowly during the dilution phase, so that at the end of the dilution phase, the pump 43 and the circuit 46 are filled with the same fluid as is present in the diluted PD concentrate container 9 and the recirculation fluid path 61.

[0111] As a mitigation measure for the air entrainment problem, it should be noted that the severity of the air problem depends on the amount of un-purged air present in the concentrate 4a or 4b during the first batch of PD fluid preparation and the size of the lines 21 and 21a leading to the point P. In Figure 9 In a further embodiment, an air / fluid sensor 47 (e.g. a capacitive or ultrasonic sensor) under the control of the control unit 40 is placed directly after the point P. The control unit 40 causes the pump 43 to pump one of the concentrates 4a, 4b until the sensor 47 detects fluid, then switches to the other concentrate 4a, 4b and performs a similar operation at least at the start of the first batch of PD fluid. The volume in the part of the lines 21 and 21a and the recirculation fluid path 61 leading to the sensor 47 is known (or sufficiently known). Therefore, the control unit 40 can determine the volume of concentrate 4a and 4b pumped by counting the strokes of the pump 43 (assuming the pump 43 is a piston or other accurate volumetric pump, or a less accurate pump combined with a flow meter or scale).

[0112] While the application has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the application is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims.

Claims

1. A system (1) for producing fluid for peritoneal dialysis, PD, the system (1) comprising: a fluid path (2) comprising one or more PD concentrate connectors (3a, 3b), each PD concentrate connector (3a, 3b) being configured to be connected to a source (4a, 4b) of one or more PD concentrate fluids, and a water connector (7a) configured to be connected to a source of water; a forward osmosis, FO, unit (6) comprising a draw side (6a) and a feed side (6b) separated by an FO membrane (6c), the FO unit (6) being fluidly connected to the fluid path (2), wherein the FO unit (6) is configured to receive one or more PD concentrate fluids at the draw side (6a) and water at the feed side (6b), wherein purified water is delivered to the one or more PD concentrate fluids through the FO membrane (6c) by means of an osmotic pressure gradient between the draw side (6a) and the feed side (6b), thereby diluting the one or more PD concentrate fluids to produce a diluted PD concentrate fluid; a concentration sensor (51) configured to sense a concentration of the diluted PD concentrate fluid; a container (9) fluidly connected or connectable to the fluid path (2), wherein the container (9) is arranged to contain the diluted PD concentrate fluid, wherein the container (9) is separate from the source (4a, 4b) of the one or more PD concentrate fluids, and wherein the fluid path (2) comprises a first recirculation fluid path (61) comprising the draw side (6a) of the FO unit (6) and the container (9); a control device (10) configured to control a degree of dilution of the one or more PD concentrate fluids based on the sensed concentration and by recirculating diluted PD concentrate fluid in the first recirculation fluid path (61) so as to meet one or more predetermined criteria, and directing the diluted PD concentrate fluid to an outlet connector (5a) while sensing a pressure of the diluted PD concentrate fluid supplied to the outlet connector (5a) with a pressure sensor (55).

2. The system of claim 1, wherein, the one or more predetermined criteria comprise at least one of: (i) the concentration of the diluted PD concentrate fluid has at least substantially a concentration equal to matching a prescribed concentration of diluted PD fluid in a final PD fluid; (ii) the concentration of the diluted PD concentrate fluid corresponds to a final degree of dilution of a PD fluid; and / or (iii) the concentration of the diluted PD concentrate fluid is within a concentration interval for a certain duration of time.

3. The system of claim 1 or 2, wherein, the control device (10) is configured to control the degree of dilution of the one or more PD concentrate fluids by controlling a flow rate of the one or more PD concentrate fluids to an inlet of the draw side (6a), and / or controlling a flow rate of water to an inlet of the feed side (6b), and / or controlling a flow rate of waste water from an outlet of the feed side (6b).

4. The system (1) according to claim 1 or 2, comprising a pump (41) positioned and arranged to at least one of (i) transfer the diluted PD concentrate fluid to or (ii) remove the diluted PD concentrate fluid from the container (9) along the line (27).

5. The system (1) according to claim 4, comprising at least one of: (i) a fluid heater (52) positioned along the pipeline (27), (ii) a concentrate pump (43) located in the first recirculation fluid path (61), wherein, the concentrate fluid pump (43) is placed in fluid parallel with a valve (45), or (iii) an air / fluid sensor (47) located in the first recirculation fluid path (61) for determining when PD concentrate fluid has reached the sensor (47).

6. The system (1) according to claim 1 or 2, wherein The fluid path (2) comprises a second recirculation fluid path (62) comprising a feed side (6b) of the FO unit (6), wherein the control device (10) is configured to recirculate water in the second recirculation fluid path (62) until the one or more predetermined criteria are met.

7. The system of claim 1 or 2, wherein, The control device (10) is configured to direct the diluted PD concentrate fluid to the outlet connector (5a) when the one or more predetermined criteria are met.

8. The system (1) according to claim 1 or 2, comprising a water container (12) configured to collect water downstream of the FO unit (6).

9. The system of claim 1 or 2, wherein, The fluid path (2) comprises a draw agent connector (3b) configured to be connected to a source (4b) of draw agent, and wherein the control device (10) is configured to supply draw agent from the source (4b) of draw agent to the fluid path (2) to achieve a prescribed concentration of draw agent (4c) in the diluted PD concentrate fluid.

10. The system (1) according to claim 1 or 2, wherein The fluid path (2) comprises an inlet connector (29a) configured to be connected to a source (30a) of effluent, and wherein the FO unit (6) is configured to receive effluent at the feed side (6b) to transport water from the effluent to the one or more PD concentrate fluids by means of the FO membrane (6c) by way of an osmotic pressure gradient, thereby diluting the one or more PD concentrate fluids and producing pre-diluted PD concentrate fluid, which is then included in the one or more PD concentrate fluids that the FO unit (6) is configured to receive.

11. The system (1) according to claim 10, comprising an effluent container fluidly connected or connectable to the fluid path (2), wherein, The effluent container is arranged to hold effluent from a patient.

12. The system (1) according to claim 1 or 2, further comprising a pre-treatment unit (8) configured to pre-treat water received via the water connector (7a) before passing the water received via the water connector (7a) to the FO unit (6).

13. The system (1) according to claim 1 or 2, comprising a pressurization device (42) configured and arranged to generate a higher pressure on the feed side (6b) of the FO unit (6) than on the draw side (6a).

14. The system (1) according to claim 1 or 2, wherein The FO membrane (6c) is configured to purify water received at the feed side (6b) into purified water.

15. A method for producing fluid for peritoneal dialysis, PD, in a system (1), the system (1) comprising a forward osmosis, FO, unit (6), the FO unit (6) comprising a draw side (6a) and a feed side (6b) separated by a FO membrane (6c), wherein, The FO unit (6) is configured to receive one or more PD concentrate fluids at the draw side (6a) and water at the feed side (6b), wherein purified water is delivered through the FO membrane (6c) by means of an osmotic pressure gradient between the draw side (6a) and the feed side (6b) to dilute the one or more PD concentrate fluids into diluted PD concentrate fluids, the method comprising: guiding (S3) the water into the feed side (6b) of the FO unit (6); guiding (S4) the one or more PD concentrate fluids into the draw side (6a) of the FO unit (6); sensing (S5) a concentration of the diluted PD concentrate fluids; guiding (S6) the diluted PD concentrate fluids into a container (9), wherein the container (9) is separate from the source (4a, 4b) of the one or more PD concentrate fluids; and controlling (S7) a degree of dilution of the one or more PD concentrate fluids during generation of diluted PD concentrate fluids based on the sensed concentration and by recirculating diluted PD concentrate fluids in a first recirculation fluid path (61) comprising the draw side (6a) of the FO unit (6) and the container (9) such that one or more predetermined criteria are met, and guiding (S12) the diluted PD concentrate fluids to an outlet connector (5a) while sensing a pressure of the diluted PD concentrate fluids supplied to the outlet connector (5a) with a pressure sensor (55).

13. The system (1) according to claim 1 or 2, comprising a pressurization device (42) configured and arranged to generate a higher pressure on the feed side (6b) of the FO unit (6) than on the draw side (6a). The FO membrane (6c) is configured to purify water received at the feed side (6b) into purified water. The FO unit (6) is configured to receive one or more PD concentrate fluids at the draw side (6a) and water at the feed side (6b), wherein purified water is delivered through the FO membrane (6c) by means of an osmotic pressure gradient between the draw side (6a) and the feed side (6b) to dilute the one or more PD concentrate fluids into diluted PD concentrate fluids, the method comprising: guiding (S3) the water into the feed side (6b) of the FO unit (6); guiding (S4) the one or more PD concentrate fluids into the draw side (6a) of the FO unit (6); sensing (S5) a concentration of the diluted PD concentrate fluids; guiding (S6) the diluted PD concentrate fluids into a container (9), wherein the container (9) is separate from the source (4a, 4b) of the one or more PD concentrate fluids; and controlling (S7) a degree of dilution of the one or more PD concentrate fluids during generation of diluted PD concentrate fluids based on the sensed concentration and by recirculating diluted PD concentrate fluids in a first recirculation fluid path (61) comprising the draw side (6a) of the FO unit (6) and the container (9) such that one or more predetermined criteria are met, and guiding (S12) the diluted PD concentrate fluids to an outlet connector (5a) while sensing a pressure of the diluted PD concentrate fluids supplied to the outlet connector (5a) with a pressure sensor (55).

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