Systems and methods for producing peritoneal dialysis fluid - Patents.com

Abstract

A system (1) and method for producing fluids for peritoneal dialysis (PD) are disclosed. The system (1) comprises a fluid pathway (2) including one or more PD concentrate connectors (3a, 3b) configured to be connected to one or more PD concentrate fluid sources (4a, 4b), respectively, and a water connector (7a) configured to be connected to a water source. The system (1) further comprises a forward osmosis FO unit (6) including a draw side (6a) and a feed side (6b) separated by a FO membrane (6c). The FO unit (6) is fluidly connected to the fluid pathway (2). The FO unit (6) is configured to receive one or more PD concentrate fluids on the draw side (6a) and receive water on the feed side (6b), and the purified water is transported through the FO membrane (6c) to one or more PD concentrate fluids by an osmotic pressure gradient between the draw side (6a) and the feed side (6b). The transported purified water is further purified by the FO membrane (6c), and the one or more PD concentrate fluids are diluted to produce a diluted PD concentrate fluid.

Description

[Technical field]

[0001] The present invention relates to the field of peritoneal dialysis, and to systems and methods for producing fluids used in peritoneal dialysis. [Background technology]

[0002] Peritoneal dialysis (PD) is a method for treatment of patients suffering from renal failure. During PD, the patient's peritoneal cavity is filled with fresh PD fluid, and waste products and fluids are transferred from the patient's blood through the peritoneal membrane to the PD fluid. The spent PD fluid is then drained from the patient.

[0003] There are several types of PD: in automated peritoneal dialysis, APD, a machine is used to fill the peritoneal cavity with fresh PD fluid and drain the spent PD solution externally after a certain dwell time. This procedure is typically repeated several times overnight. 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 spent PD fluid from the patient. APD systems on the market today use centrally manufactured PD fluid that is shipped to the patient ready to use in bags that are stored in the patient's home.

[0004] Transporting PD fluid adds processing costs and has a negative impact on the environment. Storage of PD fluid in the patient's home requires space. Patient handling of PD fluid prior to processing adds to the patient's burden, and many patients find it difficult to place the PD fluid bag in the correct position before processing begins.

[0005] Therefore, there is a need to reduce the above negative consequences. Summary of the Invention

[0006] It is an object of the present disclosure to alleviate at least some of the shortcomings of the prior art. A further object is to provide a cost-effective solution for producing PD fluids at the point of care. A further object is to provide a compact solution for producing PD fluids at the point of care. Yet another object is to provide a PD fluid solution that consumes low amounts of water.

[0007] These and other objects are achieved, at least in part, by systems and methods according to the independent claims and by embodiments according to the dependent claims.

[0008] According to an aspect of the present disclosure that may be combined with any other aspect or portion thereof, the present disclosure relates to a system for generating a fluid for peritoneal dialysis (PD). The system includes a fluid pathway comprising one or more PD concentrate fluid connectors, each configured to be connected to one or more PD concentrate fluid sources, and a water connector configured to be connected to a water source. 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 fluidly connected to the fluid pathway. The FO unit is configured to receive one or more PD concentrate fluids at the draw side and receive water at the feed side and transfer purified water from the water through the FO membrane to one or more PD concentrate fluids by an osmotic pressure gradient between the draw side and the feed side. The one or more PD concentrate fluids are thereby diluted to generate a diluted PD concentrate fluid. The proposed system can purify water at the same time as diluting the PD concentrate, thereby making water purification less complicated and less expensive. In one embodiment, the transferred purified water is further purified by the FO membrane of the FO unit.

[0009] According to another aspect of the present disclosure, which may be combined with any other aspect or portion thereof, the system includes a concentration sensor configured to detect a concentration of a diluted PD concentrate fluid, and a controller configured to control a degree of dilution of one or more PD concentrate fluids during generation of a diluted PD concentrate fluid based on the detected concentration such that one or more predetermined criteria are met.

[0010] According to another aspect of the present disclosure that can be combined with any other aspect or portion thereof, the one or more predetermined criteria include a concentration of the diluted PD concentrate fluid having a concentration equal to or close to (e.g., at least substantially equal to) a concentration that matches a specified concentration of the diluted PD fluid in the final PD fluid, a concentration of the diluted PD concentrate fluid that corresponds to a final dilution degree of the PD fluid, and / or the concentration of the diluted PD concentrate fluid being within a concentration range for a certain period of time.

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

[0012] According to another aspect of the present disclosure, which may be combined with any other aspect or portion thereof, a system includes a container fluidly connected or connectable to a fluid pathway, the container being arranged to receive a diluted PD concentrate fluid.

[0013] According to another aspect of the present disclosure that can be combined with any other aspect or portion thereof, the fluid pathway includes a first recirculation fluid pathway including a draw side of the FO unit and a vessel, and the controller is configured to control the degree of dilution by recirculating the diluted concentrate fluid in the first recirculation fluid pathway until one or more predetermined criteria are met.

[0014] According to another aspect of the present disclosure, which may be combined with any other aspect or portion thereof, the system includes a pump positioned and arranged to at least one of: (i) deliver dilute PD concentrate fluid to the container along the line; or (ii) remove dilute PD concentrate fluid from the container along the line.

[0015] According to another aspect of the present disclosure, which may be combined with any other aspect or portion thereof, the system includes at least one of: (i) a fluid heater disposed along the line; (ii) a concentrate pump disposed in the recirculation fluid path, optionally in fluid parallel with the valve; or (iii) an air / fluid sensor disposed in the recirculation fluid path to determine when the PD concentrate fluid reaches the sensor.

[0016] In another aspect of the present disclosure that can be combined with any other aspect or portion thereof, the fluid pathway includes a second recirculation fluid pathway that includes a feed side of the FO unit, and the control device is configured to recirculate water in the second recirculation fluid pathway until one or more predetermined criteria are met.

[0017] According to another aspect of the present disclosure, which may be combined with any other aspect or portion thereof, the control device is configured to direct the diluted PD concentrate fluid to the outlet connector based on one or more predetermined criteria being met.

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

[0019] According to another aspect of the present disclosure that can be combined with any other aspect or portion thereof, the fluid pathway includes an osmotic agent connector configured to be connected to an osmotic agent source, and the controller is configured to supply an osmotic agent from the osmotic agent source to the fluid pathway to achieve a specified concentration of the osmotic agent in the diluted PD concentrate fluid.

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

[0021] According to another aspect of the present disclosure, which may be combined with any other aspect or portion thereof, the system includes a drainage fluid container fluidly connected or connectable to the fluid pathway, the container positioned to receive drainage fluid from the patient.

[0022] According to another aspect of the present disclosure, which can be combined with any other aspect or portion thereof, the system includes a pre-treatment unit configured to pre-treat water received via the water connector before it flows to the FO unit.

[0023] According to a further aspect of the present disclosure that may be combined with any other aspect or portion thereof, the present disclosure includes a method for producing a peritoneal dialysis fluid (PD) in a system including a forward osmosis (FO) unit. The FO unit includes 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 receive water at the feed side, and to transfer purified water from the water to the one or more PD concentrate fluids through the FO membrane by 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 includes 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 of the present disclosure, which may be combined with any other aspect or portion thereof, a method includes detecting a concentration of a diluted PD concentrate fluid and controlling a degree of dilution of one or more PD concentrate fluids during production of a diluted PD concentrate fluid based on the detected concentration such that one or more predetermined criteria are met.

[0025] According to another aspect of the present disclosure that can be combined with any other aspect or portion thereof, the one or more predetermined criteria include a concentration of the diluted PD concentrate fluid having a concentration equal to or close to (e.g., at least substantially equal to) a concentration that matches a specified concentration of the diluted PD fluid in the final PD fluid, a concentration of the diluted PD concentrate fluid that corresponds to a final dilution degree of the PD fluid, and / or the concentration of the diluted PD concentrate fluid being within a concentration range for a certain period of time.

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

[0027] According to another aspect of the present disclosure that can be combined with any other aspect or portion thereof, the method includes directing a dilute PD concentrate fluid to a container.

[0028] According to another aspect of the present disclosure that can be combined with any other aspect or portion thereof, a method includes controlling a degree of dilution by recirculating a dilute concentrate fluid in a first recirculation fluid path that includes a draw side of a FO unit and a container until one or more predetermined criteria are met.

[0029] According to another aspect of the present disclosure that can be combined with any other aspect or portion thereof, the method includes controlling the degree of dilution by recirculating water in a second recirculation fluid path that includes a feed side of the FO unit until one or more predetermined criteria are met.

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

[0031] According to another aspect of the present disclosure that can be combined with any other aspect or portion thereof, a method includes providing an osmotic agent from an osmotic agent source to a fluid pathway to achieve a predetermined concentration of the osmotic agent in the dilute PD concentrate fluid.

[0032] According to another aspect of the invention that may be combined with any other aspect or portion thereof, a method includes directing an effluent from an effluent source to a feed side of a FO unit and transporting water through a FO membrane from the effluent to one or more PD concentrate fluids by an osmotic gradient between the draw side and the feed side, the one or more PD concentrate fluids being thereby diluted to produce pre-diluted PD concentrate fluids that are included in one or more PD concentrate streams that the FO unit is configured to receive.

[0033] According to another aspect of the present disclosure, which can be combined with any other aspect or portion thereof, the method includes pre-treating water received via the water connector before passing it through the FO unit.

[0034] According to another aspect of the present disclosure that can be combined with any other aspect or portion thereof, the method includes directing the diluted PD concentrate fluid to an outlet container when one or more predetermined criteria are met.

[0035] According to another aspect of the present disclosure that can be combined with any other aspect or portion thereof, one of the one or more PD concentrate sources includes a fluid including one or more of lactate, acetate, citrate, bicarbonate, NaCl, MgCl2, CaCl2, and KCl.

[0036] According to yet another aspect of the present disclosure, which may be combined with any other aspect or portion thereof, the present disclosure relates to a computer program comprising instructions for causing a system according to any system aspect to perform the steps of a method according to any method aspect.

[0037] According to a further aspect of the present disclosure, which may be combined with any other aspect or part thereof, the present disclosure relates to a computer readable memory storing a computer program of the computer aspect.

[0038] Further features and advantages will be described in or will be apparent from the following detailed description and drawings. The features and advantages described herein are not all-inclusive, and in particular many additional features and advantages will be apparent to those skilled in the art in view of the drawings and description. Also, any particular embodiment need not have all of the advantages recited herein, and it is expressly contemplated that each advantageous embodiment may be separately claimed. Furthermore, it should be noted that the language used in this specification has been selected primarily for readability and instructional purposes, and is not intended to limit the scope of the inventive subject matter. [Brief description of the drawings]

[0039] [Figure 1] 1 and 4-9 show systems for producing fluids for PD, according to some embodiments. [Diagram 2] 2 and 3 are flow charts illustrating methods for producing fluids for PD, according to some embodiments. [Diagram 3] 2 and 3 are flow charts illustrating methods for producing fluids for PD, according to some embodiments. [Figure 4] 1 and 4-9 show systems for producing fluids for PD, according to some embodiments. [Diagram 5] 1 and 4-9 show systems for producing fluids for PD, according to some embodiments. [Figure 6] 1 and 4-9 show systems for producing fluids for PD, according to some embodiments. [Figure 7] 1 and 4-9 show systems for producing fluids for PD, according to some embodiments. [Figure 8] 1 and 4-9 show systems for producing fluids for PD, according to some embodiments. [Figure 9] 1 and 4-9 show systems for producing fluids for PD, according to some embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] In the following disclosure, several embodiments of systems and methods for producing fluids for PD are described. Each embodiment utilizes a forward osmosis (FO) unit to dilute one or more PD concentrates using purified water transferred from the water over a FO membrane. The water is purified as it is transferred over 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 has pulled enough water through the FO membrane to reach the desired dilution. The diluted PD concentrate may have the defined composition of the final PD fluid after the FO session or may need to be mixed with additional PD concentrate, e.g., PD fluid with an osmotic agent, before having the defined composition of the PD fluid. A PD fluid may be defined as a PD fluid that is ready to be used by a patient in a PD treatment. The system can be used for different variations of automated PD, including online mixing of PD fluids and batch mixing of PD fluids. The water may be pretreated before being used in the FO unit 6.

[0041] The water used in the FO unit may be raw water (e.g., tap water) or pretreated raw water. The systems described herein can include a pretreatment module configured to treat the raw water before it is provided to the FO unit.

[0042] In the following, a system for producing a fluid for PD is described with reference to FIG. 1. References that are the same throughout the figures are generally not repeated. The system 1 comprises a fluid path 2, a number of connectors, and a forward osmosis (FO) unit 6. The fluid path 2 may be enclosed inside an enclosure (not shown in FIG. 1). The fluid path 2 may be part of an apparatus. The fluid path 2 comprises a number of fluid lines. These fluid lines may be a number or all of the 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 of PD concentrate fluid 4a, 4b. The source of PD concentrate fluid is typically a bag with PD concentrate fluid. Each PD concentrate connector 3a, 3b is then configured to be connected to a corresponding connector provided with a bag with PD concentrate fluid. The connectors also include a water connector 7a. The water connector 7a may be a water port. The water connector 7a is typically configured to be connected to a hose connected to a raw water source, for example a water supply. The raw water may therefore be tap water. The water may be pre-treated before being fed to the FO unit 6.

[0043] The system 1 may also comprise a pretreatment unit (8, Figs. 4-8) configured to pretreat the water received via the water connector 7a before it is sent 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, for example 0.5-5 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 receives one or more PD concentrate fluids 4a, 4b at the draw side 6a and (pretreated) water at the feed side 6b, and is configured to transport purified water from water through the FO membrane 6c to one or more PD concentrate fluids by means of an osmotic pressure gradient between the draw side 6a and the feed side 6b. The one or more PD concentrate fluids are thereby diluted to a diluted PD concentrate fluid. A suitable FO unit for the FO unit 6 is the AquaporinTM , AsahiKASEI TM , Berghof TM , C.S.M. TM , F.T.S.H. 2 O TM , Koch Membrane Systems TM , Porifera TM , Toyoboshi TM and Toray TM may be provided by

[0044] The FO membrane 6c may be a water permeable membrane that separates water (feed side) and PD concentrate (draw side). The fluids in the different sides 6a, 6b may flow countercurrently or cocurrently. It should be noted that the water may flow in a single pass, so that the used water may pass once through the feed side 6b before flowing to a drain. Again, the FO membrane 6c may have pore sizes in the nanometer (nm) range, for example 0.5-5 nm or less, depending on the solutes that are intended to be blocked. The FO membrane 6c is typically designed to be more or less exclusively selective for water molecules, which allows the membrane to separate the water and thus further purify it from all other contaminants. The membrane geometry may be flat sheet, tubular or hollow fiber. Alternatively, the water may be recycled one or more times to the feed side 6b and / or the draw side fluid may be recycled one or more times to the draw side 6a. Purified water from water is transported over the FO membrane 6c by means of a driving force generated by the difference in osmotic pressure between the water (feed solution) and one or more PD concentrate fluids (draw solutions). This means that water becomes more concentrated throughout the FO process. Meanwhile, one or more PD concentrates become increasingly dilute throughout the FO process. The FO membrane 6c may be a water treatment membrane capable of facilitating a forward osmosis process. It is a semi-permeable membrane that allows the flow of water from a low concentrate side (feed side) to a high concentrate side (draw side). FO membranes typically include a thin rejection layer (or active layer) and an underlying porous support. The membrane geometry may be flat sheet, tubular or hollow fiber.

[0045] More specifically, a first PD concentrate bag 4a is connected to a first PD concentrate connector 3a via a first bag connector (not shown). A first fluid line 21 is fluidly connected between the first PD concentrate connector 3a and an inlet port of the draw side 6a. Thus, the first fluid line 21 connects the first PD concentrate connector 3a and the draw side 6a. A second PD concentrate bag 4b is connected to a second PD concentrate connector 3b via a second bag connector (not shown). A 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 pathway 2 comprises a second PD concentrate connector 3b. The second PD concentrate connector 3b is configured to be connected to a source of fluid including an osmotic agent. Alternatively, fluid line 21a may be connected to a second fluid line 22 to supply PD concentrate from a second PD fluid bag 4b to the dilute PD fluid.

[0046] The second fluid line 22 is fluidly connected between the outlet of the draw side 6a and the 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 the fluid line 5 configured to transport the final PD fluid directly to a patient's catheter, a cycler for pumping the fluid to the patient, or 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 the flow rate of the PD concentrate fluid in the first fluid line 21 (if the pump 43 is not provided). In some embodiments, the third pump 43 is configured to control the flow rate of one or more PD concentrate fluids in the first fluid line 21, and thus to the draw side 6a or the container 9, if present. The container 9 is further described 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 the drain connector 12a. Thus, the fourth fluid line 26 connects the feed side 6b and the drain connector 12a. The second pump 42 is configured to control the flow rate of the waste water from the feed side 6b. The second pump 42 is configured to operate with the fourth fluid line 26 in the illustrated embodiment. The drain connector 12a is configured to be connected to a corresponding connector of a drain line (not shown), which may be connected to a drain to remove the waste water after use, or to a bag or water container 12 for 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 the next FO session, for example during the first part of the FO session, so that water consumption is reduced.

[0047] The concentration sensor 51 is configured to detect the concentration of the fluid in the second fluid line 22. Thus, the concentration sensor 51 is positioned to detect the concentration of the diluted PD concentrate fluid. In some embodiments, the system 1 includes a container 9. The container 9 is fluidly connected or connectable to the fluid path 2. The container 9 is arranged to receive the diluted PD concentrate fluid. The container 9 may also be used to collect one or more concentrates before feeding to the draw side 6a. An alternative embodiment is to pre-fill one or more concentrates into the container 9 for mixing to form a batch, which may be a batch for the entire process. Additional concentrates can then be added after the dilution process. In the embodiment including the container 9, a fifth fluid line 27 is fluidly connected between the second fluid line 22 downstream of the concentration sensor 41 and the container 9. Thus, 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. Thus, the sixth fluid line 23 fluidly connects the vessel 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 vessel 9, the sixth fluid line 23, and a portion of the first fluid line 21 form a first recirculation fluid pathway 61. Thus, the fluid pathway 2 includes a first recirculation fluid pathway 61 that includes the draw side 6a of the FO unit 6 and the vessel 9. The controller 10 is configured to control the degree of dilution by recirculating the diluted concentrate fluid in the first recirculation fluid pathway 61 until one or more predetermined criteria are met.

[0048] The concentration sensor 51 may be, for example, a conductivity sensor configured to sense the conductivity of the fluid, or a resistivity sensor configured to sense the resistivity of the fluid. Even if, for example, a resistivity sensor is used, the sensed value may be converted to a conductivity value as needed and known in the art. The conductivity may likewise be converted to a resistivity.

[0049] In some embodiments, the system 1 comprises a seventh fluid line 19 disposed between the third fluid line 25 and the fourth fluid line 26. The seventh fluid line 19 thus connects the third fluid line 25 and the fourth fluid line 26. The feed side 6b, a portion of the third fluid line 25, a portion of the fourth fluid line 26, and the seventh fluid line 19 are included in a second recirculation fluid path 62. The fluid path 2 in the illustrated embodiment thus forms a second recirculation fluid path 62 that includes the feed side 6b of the FO unit 6a. The control device 10 is configured to recirculate the water in the second recirculation fluid path 62 until one or more predetermined criteria are met. The circulated water may be collected in an additional container (not shown), and water to / from the additional container and the second recirculation path 62 may be passed through one or two ports in the additional container. An additional valve (not shown) may be configured to control the flow of water to and from the additional container.

[0050] In some embodiments, the effluent, i.e., the used PD fluid from the patient, is used as the feed solution before the water is used as the feed solution. The FO unit 6 is then arranged to receive the effluent at the feed side 6b. Water is transferred from the effluent through the FO membrane 6 to one or more PD concentrate fluids by means of an osmotic gradient between the draw side 6a and the feed side 6b, thereby diluting the one or more PD concentrate fluids to produce a pre-diluted PD concentrate fluid. The pre-diluted PD concentrate fluid is collected in the container 9. The pre-diluted concentrate fluid is then one of the one or more PD concentrate fluids that the FO unit 6 is arranged to receive. Thus, the one or more PD concentrates may be pre-diluted with water withdrawn from the effluent via the FO before being further diluted with purified water from the raw water or pre-treated water. This saves additional water. In such an embodiment, the fluid path 2 may comprise an inlet connector 29a. The 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 to the third fluid line 25. The inlet connector 29a is connected to a corresponding connector (not shown) attached to a drain source 30a. The drain source 30a may be a drain container or bag having drainage from a previous drain of drainage from the PD patient. Thus, in some embodiments, the fluid path 2 comprises an inlet connector 29a configured to be connected to the drain source 30a, e.g., a drain container. In some embodiments, the system comprises a drain container fluidly connected or connectable to the fluid path 2. The drain container is arranged to receive drainage from the patient.

[0051] The system 1 further comprises a controller 10. The controller 10 comprises a control unit 40 comprising a processor and a memory. The memory typically stores a program that controls the system 1 when executed by the processor. The control unit 40 may also comprise a communication interface that allows the control unit 40 to communicate data and signals to and from the components of the system 1, for example, to send control signals to the valves and pumps, and to receive sensed data from concentration sensors and feedback signals from the valves and pumps. The controller 10 may also comprise any one or more of the pumps 41, 42, 43 shown. The controller 10 may also include valves that are not included in FIG. 1 for ease of explanation. The valves described herein are typically on / off valves and may be two-way or three-way valves.

[0052] In some embodiments, the controller 10 is configured to control the dilution degree of one or more PD concentrate fluids during 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. Depending on the current stage in the production of the PD fluid, there may be different criteria used, which are described in more detail below. In some embodiments, the controller 10 is configured to control the dilution degree of one or more PD concentrate fluids by controlling the flow rate of one or more PD concentrate fluids to the inlet of the draw side 6a, and / or by controlling the flow rate of water to the inlet of the feed side 6b, and / or by controlling the flow rate of wastewater from the outlet of the feed side 6b. The flow rate of one or more PD concentrate fluids to the inlet of the draw side 6a may be controlled by a first pump 41. The flow rate of water to the inlet of the feed side 6b may be controlled by a second pump 42. Any one or more of the pumps 41-43, and any other pumps described herein, may be volumetric pumps, such as, for example, piston or membrane pumps. Any one or more of pumps 41-43, and any other pumps described herein, may alternatively be flow pumps used in operation in conjunction with a flow meter or metering scale.

[0053] In some embodiments, only the first type of PD concentrate is used as the draw solution. The PD concentrate then includes, for example, a buffer. The PD concentrate then includes, for example, a buffer. The other second type of PD concentrate includes, for example, an osmotic agent. The other second type of PD concentrate is, for example, glucose. Alternatively, the other second type of PD concentrate is used as the draw solution together with the first type of PD concentrate. Thus, the control device 10 is configured to supply an osmotic agent from the osmotic agent source 4b to the fluid path 2 to achieve a defined concentration of the osmotic agent in the diluted PD concentrate fluid.

[0054] The diluted PD concentrate may be recirculated in the first recirculation fluid path 61 until the sensed concentration meets one or more criteria for a final PD fluid. Typically, the sensed concentration should be within a certain interval. Once this is achieved, the controller 10 is configured to direct the diluted PD concentrate fluid to the outlet connector 5a. Another criterion may be, for example, that the PD fluid is ready and a certain time has passed.

[0055] The final PD fluid has a composition of PD concentrates and water that achieves a defined or predetermined composition. It is thus known what concentration of one or more PD concentrates the final PD fluid should have, such as 1.36%, 2.27%, or 3.86% glucose, thus defined. The final PD fluid is the PD fluid that is ready to be delivered to the patient's peritoneal cavity. The production rate may be batch-wise, i.e., a specific volume of the final PD fluid should be produced. In that case, the specific volume is the batch. Alternatively, the production of the final PD fluid is continuous, which is delivered until the controller 10 determines that the delivery should stop.

[0056] One of the one or more PD concentrate sources 4a may include a fluid that includes one or more of lactate, acetate, citrate, bicarbonate, KCl, MgCl2, CaCl2, and NaCl. For example, the PD concentrate source includes a fluid that contains a buffer, such as one or more of lactate, citrate, acetate, and bicarbonate, which when diluted with water and possibly other PD concentrates, results in a final PD fluid having a pH applicable for PD processing, and one or more of KCL, MgCl2, CaCl2, and NaCl.

[0057] FIG 2 is a flow chart of a method of producing a pre-diluted PD fluid with effluent and one or more PD concentrates, according to some embodiments. FIG 3 is a flow chart of a method of generating a fluid for PD, according to some embodiments described herein. The method may be implemented as instructions on a computer program and stored in the memory of the control unit 40. The method has been described in conjunction with the flow charts of FIG 2 and FIG 3. Dotted boxes correspond to alternative or optional functions or steps.

[0058] 2, the method at S1a includes directing an effluent from an effluent source 30a to a feed side 6b of a FO unit 6a. The method at S1b also includes directing one or more PD concentrate fluids to the draw side 6a. Water from the effluent is then transported from the effluent to the one or more PD concentrate fluids through the FO membrane 6 by means of an osmotic gradient between the draw side 6a and the feed side 6b, thereby diluting the one or more PD concentrate fluids and generating a pre-diluted PD concentrate fluid. The pre-diluted concentrate fluids are then included in one or more PD concentrate fluids that the FO unit 6 is configured to receive. In one embodiment, the one or more PD concentrates used as draw solutions include a PD concentrate fluid that includes one or more buffers.

[0059] The method at S1c further includes sensing the concentration of the diluted PD concentrate fluid, for example with concentrate sensor 51. The method also includes directing the diluted PD concentrate fluid of S1d to container 9. Thus, the PD concentrate may be pre-diluted using effluent from the patient's previous drain.

[0060] A method for producing a PD fluid is described with reference to the flow chart of FIG. 3. The method described in the flow chart of FIG. 2 may be performed before the method described in FIG. 3. The method may be performed using any of the systems 1 described herein. Before the method is started, the system 1 is connected to a water source 7, for example to a water pipe via a hose, via the water connector 7a. The drain connector 12a is connected to a drain or drain bag to collect the used water. The outlet connector 5a is connected to the fluid line 5. A dedicated bag with the PD concentrate is connected to the PD concentrate connectors 3a, 3b. The water may come directly from the water supply, which is considered as "raw water". The method can then pre-treat the raw water before it is further used. In other words, the method in S2 involves pre-treating the water received via the water connector 7a before it flows to the FO unit 6. Alternatively, the water is already pre-treated and can be fed directly to the FO unit 6. Pre-treatment can include removal of large particles, for example using a sediment filter, and / or removal of chlorine and their variants, such as chloramines, using a mixed bed. In either case, the method at S3 includes directing the (pretreated) water to 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 FIG. 1). The water is pumped to and through the feed side 6b using a second pump 42. At the same time, the method at S4 includes directing one or more PD concentrate fluids to the draw side 6a of the FO unit 6.

[0061] In one embodiment, a PD concentrate fluid using one or more buffers is used as the draw solution. This PD concentrate fluid may be provided in a first PD concentrate bag 4a. The PD concentrate fluid with one or more buffers is then directed (e.g., using valves not shown in FIG. 1 ) to the draw side 6a and pumped using a first pump 41. Alternatively, the draw solution is a mixture of two different PD concentrate fluids. In one 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 fluids from the first and second bags 4a, 4b. These fluids are then directed and pumped to the container 9 before being used as the draw solution in the FO unit 6. Still alternatively, the draw solution is one or more pre-diluted PD concentrates that have been pre-diluted using effluent from the patient. In either case, the method includes directing one or more PD concentrates to the draw side 6a of the FO unit 6. FO unit 6 produces a diluted PD concentrate.

[0062] The method of S5 senses the concentration of the diluted PD concentrate fluid. The sensed concentration determines, for example, 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, the method in S6 includes directing the diluted PD concentrate fluid to a vessel 9. The method may include recirculating the diluted PD concentrate in a first recirculation fluid path 61 that includes the vessel 9 until the concentration reaches a concentration that satisfies the concentration of one or more PD concentrates for the final PD fluid. That is, the method of S7 may include controlling the degree of dilution by recirculating the diluted concentrate fluid in a first recirculation fluid path 61 that includes the draw side 6a of the FO unit 6 and the vessel 9 until one or more predetermined criteria are met. During recirculation, the diluted PD concentrate continues to draw water from the feed solution and becomes increasingly diluted. This recirculation continues until one or more criteria are met. If the concentration of the diluted PD concentrate meets one or more criteria at S7c, the method may include collecting the diluted PD concentrate in a container 9 or directing the diluted PD concentrate fluid to an outlet connector 5a at S12.

[0063] If only a solution containing a buffer and / or electrolyte agent is used as the draw solution, the method at S10 includes providing a PD concentrate fluid containing an osmotic agent to the diluted PD concentrate solution. A predetermined amount of the PD concentrate fluid containing an osmotic agent may be provided from an osmotic agent source, from the second PD concentrate fluid bag 3b into the container 9 or into the fluid path 2, e.g., into the second fluid line 22, to achieve a defined concentration of the osmotic agent in the diluted PD concentrate fluid. The method may then include directing the diluted PD concentrate fluid to the outlet connector 5a. If a PD concentrate fluid containing an osmotic agent is used as the draw solution together with a PD concentrate fluid having a buffer, the method may include directing the diluted PD concentrate fluid to the outlet connector 5a without directing the diluted PD fluid through the container 9. In other words, if the concentration of the diluted PD concentrate fluid corresponds to the final dilution of the PD fluid, the method may include directing the diluted PD concentrate fluid to the outlet connector 5a. If not, the method at S11 may provide additional PD concentrate fluid from one or more PD concentrate sources 4a, 4b to achieve the final PD fluid composition.

[0064] The method in S7a can control the dilution degree of one or more PD concentrate fluids by controlling the flow rate of one or more PD concentrate fluids to the inlet of the draw side 6a and / or by controlling the flow rate of water at the inlet of the feed side 6b in S7b. The flow rate of one or more PD concentrate fluids to the inlet of the draw side 6a is controlled by the third pump 43 or the first pump 41. The drain flow rate from the feed side 6b is typically controlled by the second pump 42. Alternatively, the flow rate of water to the feed side 6b is controlled (the second pump 42 can then be placed in the third fluid line 25. The amount of PD concentrate in the desired composition PD fluid is known in advance together with the concentration of the PD concentrate). Thus, for each batch of final PD fluid, the amount of PD concentrate fed to the draw side 6a is known. If the dilution PD fluid is not recirculated, the one or more PD concentrate fluids need to draw off the necessary water in one pass to dilute the one or more PD concentrates to a final dilution degree corresponding to the dilution degree of the specified PD fluid. The sensed concentration is then used as feedback to the first pump 41 (positioned as in FIG. 1 ) and optionally the second pump 42 to adapt the pump speed so that the concentration meets one or more criteria for the final PD fluid. If a PD concentrate fluid containing one or more osmotic agents is fed to a diluted PD concentrate fluid after a FO session, the criterion is that the concentration of the diluted PD concentrate fluid is equal to or close to a concentration that matches a specified concentration of the diluted PD fluid in the final PD fluid. The target concentration of the PD concentrate fluid from the first PD concentrate 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 bag 4b (in the final PD fluid). If a PD concentrate fluid containing one or more osmotic agents is fed to a diluted PD concentrate fluid after a FO session, the criterion is that the concentration of the diluted PD concentrate fluid is equal to or close to a concentration that matches a specified concentration of the diluted PD fluid in the final PD fluid. The method can ensure uniformity by sensing the concentration and monitoring that the concentration of the diluted PD concentrate fluid is within a concentration range for a certain period of time. Thus, the dilute PD concentrate fluid is now a ready made PD fluid.

[0065] The used water in the FO becomes richer and therefore more concentrated. The method may include directing the used water to a drain, recirculating the used water to be used again, or directing the used water downstream of the FO unit 6 to the water container 12 at S8, or a combination thereof. Thus, the water may be used in a single pass so that fresh water is always used in the FO. Alternatively, a predetermined amount of water is used and recirculated, which is directed to the drain after the FO is finished or collected in the water container, so that it can be used for the next FO session. In yet another embodiment, a major portion of the used water is recirculated, some used water is directed to the drain, and some fresh water is introduced. Thus, in some embodiments, the method at S7 includes controlling the dilution degree by recirculating the water in the second recirculation fluid path 62, which includes the feed side 6b of the FO unit 6a, until one or more predetermined criteria are met.

[0066] To provide a final PD fluid that can be introduced directly into the patient's abdominal cavity, the method can include heating the fluid in fluid pathway 2 with heater 52 (FIGS. 4-8). Heater 52 can also be used to disinfect fluid pathway 2 of system 1.

[0067] A different APD system 1 is now described that uses FO to purify water and simultaneously dilute the PD concentrate fluid. FIG. 4 shows the system 1 with batch PD fluid production. FIG. 5 shows the same system as FIG. 4 with the addition of the ability to use effluent as a feed solution to pre-dilute the PD concentrate. FIG. 6 shows the system 1 in which PD concentrate from both the first PD concentrate bag 4a and the second PD concentrate bag 4b can be introduced into the second fluid line 22, so that one or more PD concentrate fluids can be pumped to the vessel 9 using the first pump 41. Criteria that are the same throughout the figures may not be repeated in the text and include all structures, functions, and alternatives described in connection with the criteria.

[0068] The system 1 of FIG. 4 is described with a proposed sequence for producing fluids for PD, including a diluted PD concentrate fluid and a final PD fluid. The system 1 has the same reference numbers for parts that are the same as the system of FIG. 1. Additionally, the system includes a third pump 43 (shown in phantom in FIG. 1) configured to control the flow rate of one or more PD concentrate fluids in the first fluid line 21. The first fluid line 21 is also provided with a first valve 31 arranged to operate with the first fluid line 21 upstream of a connection point of the fluid line 21a to the first fluid line 21. The second valve 32 is configured to operate with the fluid line 21 upstream of the same connection point of the fluid line 21a to the first fluid line 21. The third pump 43 is configured to operate with the first fluid line 21 downstream of the same connection point. The third valve 33 is arranged to operate with a sixth fluid line 23. The sixth fluid line 23 is arranged between the first port 9a of the vessel 9 and the first fluid line 21. The fourth valve 34 is configured to operate with the third fluid line 25 downstream of the pre-treatment unit 8 between the pre-treatment unit 8 and the inlet to the feed side 6b. The fifth valve 35 is disposed in the seventh fluid line 19 between its connection point to the third fluid line 25 and its connection point to the fourth fluid line 26. The tenth fluid line 18 is disposed between the seventh fluid line 19 and the second fluid line 22. The sixth valve 36 is configured to operate with the tenth fluid line 18. The seventh valve 37 is configured to operate with the second fluid line 22 proximate to the outlet connector 5a. The eighth valve 38 is configured to operate with the pressure relief line 28 from the vessel 9. The ninth valve 39 is configured to operate with the seventh fluid line 19 downstream of its connection point to the fourth fluid line 26 and the tenth fluid line 18. The ninth valve 39 controls the flow to the drain connector 12a.

[0069] The fifth fluid line 27 is fluidly connected to the second fluid line 22 and the second port 9b of the vessel 9. Thus, the fifth fluid line 27 connects the second fluid line 22 and the second port 9b of the vessel 9. The tenth valve 44 is arranged to operate with the second fluid line 22 between its connection to the tenth fluid line 18 and its connection to the fifth fluid line 27. The first pump 41 is configured to operate with the fifth fluid line 27 to pump fluid to or from the vessel 9, instead of the second fluid line 22 as in the system of FIG. 1. The heater 52 is configured to operate with the fifth fluid line 27 between the vessel 9 and the first pump 41, but may alternatively be arranged to heat the fluid elsewhere in the fluid pathway 2. The temperature sensor 53 is configured to sense the temperature of the fluid in the fifth fluid line 27 downstream of the heater 52. Here, the concentration sensor 51 is positioned to sense the concentration of fluid in the fifth fluid line 27 , here between the first pump 41 and the reservoir 9 .

[0070] The first pressure sensor 54 is configured 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 configured to sense the pressure in the second fluid line 22, which is the pressure of the final PD fluid delivered to the outlet connector 5a. The level sensing device 11 is configured to sense the fluid level in the container 9. The level sensing device 11 includes, for example, an analog 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 the volume criterion. The volume of the diluted PD concentrate may be sensed with a level sensor or may be determined by the number of pump strokes performed by the volumetric first pump 41. An ultraviolet (UV) lamp 57 may be arranged inside the container 9 for disinfecting the container 9. The water conductivity sensor 56 is configured to sense the conductivity of the water downstream of the pre-treatment unit 8.

[0071] A proposed sequence for using the system 1 of FIG. 4 includes one or more of the following steps: 1. Start tap water pretreatment. The water connector 7a is connected to a tap water source, for example via a hose. During this step, valves 31, 32, 33, 34, 36, 37, 38 and 44 are closed, while valves 35 and 39 are open. The water is then pretreated in the pretreatment unit 8 and the conductivity is sensed by the water conductivity sensor 56. 2. The entire batch of PD concentrate fluid is volumetrically dispensed from the first PD concentrate bag 4a into 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 the PD concentrate from the first PD concentrate bag 4a. The level sensing device 11 senses the level in the container 9. 3. The entire batch of PD concentrate fluid is volumetrically dispensed from the second PD concentrate bag 4b into the container 9. During this step, valves 31, 34, 35, 36, 37, 39, 44 are closed and valves 32, 33, 38 are open. The third pump 43 pumps the PD concentrate from the second PD concentrate bag 4b. The level sensing device 11 senses the level in the container 9. 4. Priming the FO filter with water involves pumping pre-treated 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 pre-treated in pre-treatment unit 8, the conductivity is sensed by water conductivity sensor 8, and the pre-treated water is pumped by second pump 42 through feed side 6b and out through drain connector 12a. 5. FO / mixing session. Pretreated tap water is pumped through FO unit 6. The flow rate pumped by second pump 42 becomes the drain flow through drain connector 12a. First pump 41 runs forward to recirculate the fluid in vessel 9 through first FO unit 6, through third valve 33, and then back to vessel 9. Level sensing device 11 and conductivity sensor 51 monitor the FO session (including mixing) in terms of the evolution of the volume and composition of the developing PD fluid. The FO session continues until a target concentration, e.g., a target conductivity, is reached. The target concentration of the diluted PD concentrate from first PD concentrate bag 4a is calculated based on the target osmotic agent concentration in the final PD fluid. During this session, valves 31, 32, 35, 36, and 37 are closed while valves 33, 34, 38, 39, and 44 are open. Water is pre-treated in pre-treatment unit 8, the conductivity of the pre-treated water is sensed by water conductivity sensor 56, second pump 42 provides water flow to feed side 6b and first pump 41 provides flow to draw side 6a, level sensing device 11 senses the level in vessel 9, and conductivity sensor 51 senses the conductivity. 6. a. Transmembrane Pressure Release. Due to the remaining concentration gradient between the water side (feed side 6b) and the PD fluid side (draw side 6a) of the FO unit 6, a large transmembrane pressure can develop if the two sides remain tightly separated. This pressure can damage the FO unit 6 or the fluid pathways surrounding it. By opening the draw side 6a to drain and the feed side to pretreatment, the concentration difference between the feed and draw sides is sufficiently equalized to allow it to be closed to drain without the risk of too high a transmembrane pressure. During this step, valves 31, 32, 33, 35, 37, and 38 are closed, while valves 34, 36, 39, and 44 are open. As an alternative to b.6a, the transmembrane pressure release can be achieved by introducing the diluted concentrate to the feed side of the FO unit to increase its concentration and thereby slow down the water extraction process. This serves two purposes; the dilution process can be better controlled to reach the target dilution while the recirculation is maintained and the transmembrane pressure build-up is avoided as the water extraction process is eventually stopped. Introducing the diluted concentrate to the feed side may be performed by pump 41 via valves 34, 35, 36 and / or by FO expansion of the withdrawal volume trapped between valves 33 and 34. Alternatively, the effluent can be introduced for the same purpose (Figure 5). Fine tuning of the water extraction can be achieved by controlling the amount of diluted concentrate, effluent and pretreated water on the feed side. 7. Provide PD Fluid. Once the desired concentration is reached, the PD concentrate fluid is diluted so that the diluted PD concentrate fluid has the concentration as the PD fluid, referred to herein as the final PD fluid. During this step, valves 31, 32, 33, 34, 35, 36, 39, 44 are closed and valves 37, 38 are open. A first pump 41 provides a flow of PD fluid from the container 9 to the outlet connector 5a, and pressure is sensed by a second pressure sensor 55. 8. Drain FO unit 6. Draining FO unit 6 into vessel 9 may be performed by having first pump 41 pump in the reverse direction. During this step, valves 31, 32, 34, 35, 36, 37, 38, 39 are closed and valves 33, 44 are open. First pump 41 and first pressure sensor 54 are operational. Alternatively, step 8 can be performed before step 7 to also send PD fluid volume to the draw side. In general, the steps do not have to be performed in the order listed. 9. Drain vessel 9. Vessel 9 may be drained by running 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. 10. Steps 2-9 are repeated at least once.

[0072] The proposed system 1 may be used to provide PD fluid to a patient, a PD cycler, or a PD fluid container. The heater 52 may be used to heat disinfect the system 1, including the FO unit 6 and the FO membrane 6c. This allows for reuse of the FO membrane 6c.

[0073] FIG. 5 shows the system 1 as in FIG. 4, further comprising an eighth fluid line 29 connected between the inlet port of the feed side 6a and the fourth valve 34, between the inlet connector 29a and the third fluid line 25. The eighth fluid line 29 thus fluidly connects the inlet connector 29a and the inlet port of the feed side 6a. The drain line may be connected to the inlet connector 29a and configured to pass the drain from the patient to the inlet connector 29a. The drain can then be used as a feed solution, as previously described in connection with the flow chart of FIG. 2. A water extraction from the drain is then performed as a first step to pre-dilute the PD concentrate as much as possible. Raw water FO can be used to continue the dilution until the PD fluid composition is reached.

[0074] FIG. 6 shows the system 1 with an alternative configuration 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. The PD concentrate may then be fed to the container 9 by operating the first pump 41 in a negative direction. The PD concentrate is then used as a draw solution, as explained above, by operating the first pump 41 in a forward direction. In some embodiments, the PD concentrate fluid from the first fluid bag 4a is fed to the container 9 by operating the first pump in a negative direction. The PD concentrate fluid from the first fluid bag 4a is then used as a draw solution and is diluted. The diluted PD concentrate fluid may be collected in the container 9 once it reaches a predetermined concentration. The first pump 41 can then deliver a predetermined amount of PD concentrate from the second fluid bag 4b by operating the first pump 41 in a negative direction. Now, the fluids in the container 9 can be mixed by recirculating the fluids in the first recirculation fluid path 61 until a mixing criterion is met. The mixing criterion can include that the concentration has a value within a predetermined interval for a certain time. Alternatively, a mixing chamber (not shown) is fluidly disposed in the second fluid line 22 between the fifth fluid line 27 and the outlet connector 5a. The fluids can then be mixed in the mixing chamber on their way to the outlet connector 5a.

[0075] The proposed sequence described above produces PD fluids batchwise. System 1 may also be used to produce PD fluids on-line with one or more PD concentrates and FO purified water. The basic principle of diluting the PD concentrate to the nominal PD fluid composition is the same as the proposed sequence, but the control mechanism for producing the PD fluid is different. Instead of recirculating a batch of developing diluted P concentrate fluid until enough purified water is extracted from the water on the feed side, the correct amount of water extraction (concentrate dilution) is achieved during a single pass of one or more PD concentrates through the FO unit 6. This can be achieved if one or more of the parameters that control the water extraction rate are controlled. These parameters include, but are not limited to: 1. The pressure difference between the feed side 6b and the draw side 6a of the FO unit 6. 2. Temperature representing the temperature of the fluid at the feed side 6b and / or draw side 6a. 3. Water side osmolality (discharge flow rate). 4. PD concentrate flow rate

[0076] The flow rate of the PD concentrate determines the production rate of the PD fluid and therefore should not be used for water extraction rate control if the production flow rate of the PD fluid to the outlet connector 5a is controlled, for example, by the user or by pressure feedback. The feedback mechanism used to control the water extraction rate affecting parameters can be, for example, concentration (conductivity). The above parameters may also be used to control the water extraction rate for batch production of PD fluid.

[0077] Water extraction from raw water (e.g. tap water) can be performed until the water osmolality reaches a point where the osmolality between the feed side 6b and the draw side 6a is close to zero and further water extraction is no longer possible. This minimizes wastewater flow, which means that tap water consumption is minimized. This can be achieved in several ways. In one embodiment, an online production of PD fluid is performed, where the feed and draw solutions are fed in countercurrent in the FO unit 6, while the flow rates of the draw and feed solutions are controlled to reach the PD fluid composition at the draw side outlet and approach the PD concentrate osmolality at the feed side outlet.

[0078] In another embodiment, a batch production of PD fluid is performed. Here, during the first batch, a volume of fresh tap water is recirculated in the second recirculation fluid path 62, and a volume of PD concentrate fluid 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 streamlined, its osmolality at the end of the batch production can be maximized (close to that of the PD fluid at the draw side 6a). During the second and next batches, the remaining water volume (close to the PD fluid osmolality) can be reused for water extraction during the initial stage of the second batch production, since the draw solution is highly concentrated. This can further increase the water osmolality before it is discharged. Then, an optimized amount of fresh tap water is introduced and recirculated to complete the batch production. Thus, water consumption can be minimized by maximizing the osmolality of the wastewater. Depending on the FO membrane properties, the acceptable effluent osmolality may be limited by water-side fouling and / or the onward flux of compounds concentrated on the water side. Recirculating water on the feed side has the potential advantage of reducing the risk of fouling due to increased bulk flow along the membrane.

[0079] Figures 7 and 8 show an alternative embodiment in which the system 1 produces a final PD fluid that is delivered directly to the patient or is an on-line embodiment for collection for later use in a storage container. The fluids are not mixed in the container 9 in Figures 7 and 8 as is done in Figures 1 (alternatively) and 4-6. Figures 7 and 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, which are connected to the system 1 via PD concentrate connectors 3a and 3b, respectively. In Figures 7 and 8, separate third or concentrate pumps 43a and 43b are provided for each PD concentrate fluid 4a, 4b. A forward osmosis (FO) unit 6 is also provided that includes 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, which also includes a second or feed side pump 42 operable with a fourth fluid line 26 and valves 34 and 35. The draw side outlet of FO unit 6 is provided with a concentration, e.g., conductivity, sensor 51, a temperature sensor 53, and a heater 52. The concentration, e.g., conductivity sensor 51, and temperature sensor 53 are output to control unit 40, which uses the conductivity reading as feedback while control unit 40 causes one or more concentrates to be increasingly added or diluted until a desired conductivity is reached. Control unit 40 uses a compensation factor for the conductivity reading and the temperature reading as feedback to control the amount of power applied to heater 52 to achieve a desired final PD fluid temperature, e.g., body temperature of 37° C.

[0080] Alternative embodiments of system 1 in Figures 7 and 8 also include a pretreatment unit 8 (which may include some or all of the structures, functionality, and alternatives discussed herein) for pretreating water entering system 1 via water connector 7a. Water leaving pretreatment unit 8 either (i) flows to a drain via drain connector 12a via valves 35 and 39, or (ii) flows to the feed side of FO unit 6 via valve 34. Controller 10 in both Figures 7 and 8 is configured to draw additional pretreated water from pretreatment unit 8 to the feed side, and / or one (Figure 8) or both concentrates (Figure 7) from sources 4a and / or 4b to the draw side, with the pretreated water permeating across the FO membrane to dilute one or more of concentrates 4a and / or 4b. The FO membrane also further filters and purifies the water to ensure that it is suitable for PD processing or that it is.

[0081] Figures 7 and 8 also include an outlet valve 37, an outlet connector 5a and a pressure sensor 55 for controlling the patient pump 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 outlet pump pressure to the patient at a safe level, for example below 0.21 bar (3 psig).

[0082] The differences between the systems 1 of Figures 7 and 8 include how the PD concentrate fluids 4a and 4b are introduced. In Figure 7, both PD concentrate fluids 4a and 4b (e.g., buffer and glucose) are pumped to the draw side 6a of the FO unit 6. Here, both dilute concentrate fluids are monitored by a concentration or conductivity sensor 51 for feedback to bring the final PD fluid to the desired concentration or conductivity. The parameters controlled via feedback from the concentration or conductivity sensor 51 include any one or more of the speed of the concentration pumps 43a and 43b, and the speed of the second or feed side water recirculation pump 42.

[0083] In FIG. 8, only the first PD concentrate fluid 4a (e.g., buffer) is pumped to the draw side of the FO unit 6, which is monitored by a 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., glucose) is instead pumped downstream from the FO unit 6 to a tenth fluid line 18. The second PD concentrate fluid 4b is mixed with the appropriately diluted first PD concentrate fluid 4a in a mixing chamber 60. The mixing chamber 60 may be a smaller container (e.g., 50-100 ml smaller than container 9) and operates with a pair of level sensors 60a and 60b that output to the control unit 40, which uses these outputs to maintain the level of the PD fluid in the mixing chamber 60, somewhere between the sensors. The fluids also mix in the tenth fluid line 18, such that a mixing chamber may not be required, for example as in FIG. 7. The mixing chamber 60 also functions as a gas separation chamber or gas trap and therefore may be provided in any of the embodiments of system 1 discussed herein for further mixing and / or gas separation. Gas or PD fluid may be vented from the top of the mixing chamber 60 to the drain connector 12a via a vent valve 64.

[0084] In FIG. 8, 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 past a second or final concentration or conductivity sensor 71 that outputs to the control unit 40. The control unit 40 checks 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 properly mixed and heated final PD fluid to be pumped at a safe pump pressure to the patient, cycler, or storage container or bag. If not, the control unit 40 causes the bypass valve 78 to open, allowing the improperly mixed PF fluid to be delivered to the drain connector 12a.

[0085] As mentioned above, the speed of at least one of the pumps 43a, 43b, and 42 is controlled via the control unit 40 to deliver the final PD fluid to the patient at both the desired concentration or conductivity (via feedback from the sensor 51 and possibly the sensor 71) and the desired pressure (via feedback from the pressure sensor 55). Thus, there are two feedback loops for each pump 43a, 43b, and 42 that are controlled via feedback (one or more of the pumps can be operated at a set speed). To ensure that the feedback loops are not in conflict, it is contemplated that the control unit 40 sets maximum speeds to ensure that the pressure limit of the patient is not exceeded, and controls the pumps within those maximum speeds to achieve the desired concentration or conductivity. That is, the concentration or conductivity feedback loop depends on the pressure feedback loop, as the pressure loop sets the speed limit at which the concentration or conductivity feedback loop can change the speed for the control of the concentration or conductivity. The above is true when the final PD fluid delivery flow is pressure controlled (e.g., when delivered directly to the patient). If instead it is fed to a cycler or fluid container, for example, a fixed delivery flow can be set, in which case it is the only concentration feedback loop that is active.

[0086] In any version of system 1, the flow rates generated by the second or feed side pump 42 and the third or concentrate pump 43 depend on the amount of water available for water extraction and the time available. Lower flow rates for these pumps increase the efficiency of the extraction. The flow rates of pumps 42 and 43 also depend on the size of the FO unit 6. A larger surface area for the unit increases efficiency, which may allow for higher flow rates. Overall, it is the combination of the raw water or effluent flow rate, the concentrate flow rate, and the membrane surface area that determines the efficiency.

[0087] In the example of system 1, 40 minutes are required for effluent extraction and mixing, resulting in an effluent flow rate of 75 ml / min or more. Referring again to Figure 1, if a larger volume of effluent (e.g., 8-10 liters) can instead be stored in effluent source 30a, and 8-10 liters of diluted concentrate is stored in vessel 9, a longer FO session is permitted, resulting in an effluent flow rate of approximately 15 ml / min. Such a FO session can be performed during processing and daytime, without other activity.

[0088] In a first stage, the system 1 can extract water from the effluent in a very efficient way (e.g. by reducing the effluent flow or applying transmembrane pressure (TMP)) to produce a diluted PD concentrate. In a second stage, the system 1 can further dilute the diluted concentrate to a final diluted concentrate using a small amount, e.g. tap water. This minimizes the consumption of tap water and eliminates the need for a permanent tap connection. Instead, the patient can add a small amount of tap water (e.g. 1 liter per treatment) to a water tank (not shown) before the treatment. The water tank is then the water source and is connected to the water connector 7a. The water extraction from the effluent carried out in the first stage can be performed during the current dwell, with the amount of effluent from the previous drain. Also, a large volume of effluent (e.g., 8-10 liters) can be stored in the effluent source 30a, and if 8-10 liters of diluted concentrate is stored in the vessel 9, the efficiency of water extraction from the effluent (and thus tap water savings) can be maximized, and then longer FO sessions are possible, resulting in effluent flow rates of about 15 ml / min. Such FO sessions can be performed during processing and during the day, without other activities.

[0089] Any version of the system 1 described herein also contemplates maintaining a transmembrane pressure gradient between the feed side 6b and the draw side 6a of the FO unit 6, with the feed side pressure being greater than the draw side pressure. This increases the water extraction efficiency of the FO unit 6. The transmembrane pressure gradient or ΔP may be anywhere from zero bar to 4 bar (58 psig) or more, depending on the manufacturer's specifications and / or requirements of the FO unit 6. One way to generate a higher feed side pressure is to move the second pump 42 of FIG. 1 to the third fluid line 25 so that a positive fluid pressure is instead applied to the feed side 6b of the FO unit 6. The feed side pressure is controlled by controlling the speed of the second pump 42. Alternatively or additionally, a variable flow restrictor (not shown) under the control of the control unit 40 may be added to operate with the fourth fluid line 26. Here, the control unit 40 causes the variable flow restrictor to partially occlude the line 26, creating an increased back pressure on the feed side of the FO unit 6. The second pump 42 and the flow restrictor may be referred to herein as a pressurizing device. The pressure gradient may alternatively or additionally be created by reducing the pressure on the draw side 6a of the FO unit 6. It is contemplated to hydrostatically reduce the draw side pressure by structuring the system 1 such that the diluted PD concentrate vessel 9 is lower in elevation compared to the FO unit 6.

[0090] Alternatively or additionally, it may be possible to increase the extraction efficiency 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), may be placed along the effluent fluid line 25 that heats or increases the temperature FO unit 6. The increase in effluent temperature may be, for example, anywhere from slightly above ambient temperature to 50° C. or perhaps higher, depending on the manufacture of the FO unit. The temperature to which the effluent is heated is selected such that the FO unit 6 is heated to a desired level and such that the final PD fluid delivered to the patient can be set to body temperature or near 37° C. The FO unit 6 may be found to act as a heat sink such that even if the effluent is heated to 50° C., the diluted concentrate leaving the FO unit 6 is below 50° C. and heating via the downstream heater 14 is still required. Fouling in the effluent line 25 is also a consideration when determining the temperature to which the effluent is heated, as higher temperatures may increase fouling. The reason why heating the FO unit 6 results in an increase in extraction efficiency may be related to the increased flux across the FO membrane 6c.

[0091] Thus, it is expressly contemplated that any version of system 1 discussed herein will manipulate, select, or set any one or more of the membrane surface area, feed side and draw side flow rates, pressure gradient across the membrane ΔP or transmembrane pressure, and / or temperature of 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.

[0092] With reference to Figure 9, any of the versions of system 1 described herein may include structures to mitigate potential problems with controlling the dosing of concentrates. In particular, in Figures 1, 4 and 5, concentrate from container 4b can enter the stream of concentrate from container 4a, meaning that both concentrates carry small amounts of the other concentrate with them when added (or in at least one dosing step). Also, when concentrates are added for the first time, there is air in line 21 and / or line 21a.

[0093] As a mitigation of the concentrate contamination problem, FIG. 9 directs each concentrate line 21, 21a to a common point P where the lines 21, 21a join the first recirculation fluid path 61. In this way, each concentrate 4a, 4b has its own path to the first recirculation fluid path 61, the recirculation path being part of the mixed volume. Furthermore, the third or concentrate pump 43 is moved to 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 (ignoring the stroke volume error of the pump) when the concentrate line 21, 21a is filled. Furthermore, the pump 43 is placed in parallel with the valve 45 under the control of the control unit via a loop 46 extending to both ends of the pump 43, so that the flow from the FO unit 6 can be free during the dilution phase, i.e. the valve 45 allows free flow through the recirculation fluid path 61. In one embodiment, the control unit 40 operates the pump 43 slowly at the end of the dilution phase so that the pump 43 and the loop 46 are filled with the same fluid as is present in the diluted PD concentrate container 9 and the recirculation fluid path 61.

[0094] As a mitigation of the air entrainment problem, note that the severity of the air problem depends on the amount of unenergized air present in either concentrate 4a or 4b during preparation of the first batch of PD fluid, and the size of lines 21 and 21a leading to point P. In FIG. 9, an air / fluid sensor 47, e.g., a capacitive or ultrasonic sensor, is placed just after point P under the control of control unit 40. Control unit 40 causes pump 43 to pump one of concentrates 4a, 4b, at least at the beginning of the first batch of PD fluid, until sensor 47 sees fluid, then switches to the other concentrate 4a, 4b, and so on. The volumes of lines 21 and 21a, as well as the portion of recirculation fluid path 61 leading to sensor 47, are known (or sufficiently known). Thus, control unit 40 can determine the volume of concentrates 4a and 4b pumped by counting the strokes pumped by pump 43 (assuming pump 43 is a piston or other accurate volumetric pump, or a less accurate pump in combination with a flow meter or scale).

[0095] While the present invention has been described in connection with what are presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiment, but rather, is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims.

Claims

1. A system (1) for producing a fluid for peritoneal dialysis (PD), said system (1) comprising: a fluid pathway (2) including one or more PD concentrate connectors (3a, 3b), each configured to be connected to one or more PD concentrate fluid sources (4a, 4b), and a water connector (7a), configured to be connected to a water source; a forward osmosis (FO) unit (6) including a draw side (6a) and a feed side (6b) separated by a FO membrane (6c), the FO unit (6) being fluidly connected to the fluid pathway (2), the FO unit (6) being configured to receive the one or more PD concentrate fluids at the draw side (6a) and receive water at the feed side (6b), and purified water is transported through the FO membrane (6c) to the one or more PD concentrate fluids by 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 the concentration of the diluted PD concentrate; a vessel (9) fluidly connected or connectable to the fluid pathway (2), the vessel (9) being positioned to receive the diluted PD concentrate fluid, the fluid pathway (2) including a first recirculation fluid pathway (61) including the draw side (6a) of the FO unit (6) and the vessel (9); a controller (10) configured to control a degree of dilution of the one or more PD concentrate fluids based on the sensed concentrations by recirculating the diluted PD concentrate fluid in the first recirculation fluid path (61) such that one or more predetermined criteria are met; A system (1).

2. 2. The system of claim 1, wherein the one or more predetermined criteria include at least one of: (i) the concentration of the diluted PD concentrate fluid has a concentration at least substantially equal to a concentration that corresponds to a specified concentration of diluted PD fluid in a final PD fluid; (ii) the concentration of the diluted PD concentrate fluid corresponds to a final dilution degree of the PD fluid; and / or (iii) the concentration of the diluted PD concentrate fluid falls within a concentration range for a certain period of time.

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

4. 4. The system (1) of any one of claims 1 to 3, comprising a pump (41) constructed and arranged to at least one of: (i) deliver the dilute PD concentrate fluid to the vessel (9) along a line (27); or (ii) remove the dilute PD concentrate fluid from the vessel (9) along a line (27).

5. 5. The system (1) of claim 4, comprising at least one of: (i) a fluid heater (52) disposed along the line (27); (ii) a concentrate pump (43) disposed in the recirculation fluid path (61), optionally in fluid parallel with a valve (45); or (iii) an air / fluid sensor (47) disposed in the recirculation fluid path (61) to determine when the PD concentrate fluid reaches a sensor (47).

6. 6. The system (1) according to any one of claims 1 to 5, wherein the fluid path (2) includes a second recirculation fluid path (62) including the feed side (6b) of the FO unit (6), and the control device (10) is configured to recirculate the water in the second recirculation fluid path (62) until the one or more predetermined criteria are met.

7. 7. The system of claim 1, wherein the controller (10) is configured to direct the diluted PD concentrate fluid to an outlet connector (5a) based on one or more predetermined criteria being met.

8. The system (1) according to any one of claims 1 to 7, comprising a water container (12) configured to collect the water downstream of the FO unit (6).

9. 9. The system according to any one of claims 1 to 8, wherein the fluid pathway (2) includes an osmotic agent connector (3b) configured to be connected to an osmotic agent source (4b), and the control device (10) is configured to supply an osmotic agent from the osmotic agent source (4b) to the fluid pathway (2) to achieve a defined concentration of the osmotic agent (4c) in the diluted PD concentrate fluid.

10. 10. The system (1) according to any one of claims 1 to 9, wherein the fluid pathway (2) includes an inlet connector (29a) configured to be connected to a source (30a) of effluent, and the FO unit (6) is configured to receive the effluent at the feed side (6b) and transport water from the effluent to the one or more PD concentrate fluids through the FO membrane (6c) by the osmotic gradient to dilute the one or more PD concentrate fluids to produce a pre-diluted PD concentrate fluid, and the pre-diluted PD concentrate fluid is included in the one or more PD concentrate fluids that the FO unit (6) is configured to receive.

11. 11. The system (1) of claim 10, comprising a drainage container (30a) fluidly connected or connectable to the fluid path (1), the drainage container (30a) being positioned to receive the drainage from the patient.

12. The system (1) according to any one of claims 1 to 11, further comprising a pre-treatment unit (8) configured to pre-treat the water received via the water connector (7a) before it flows to the FO unit (6).

13. 13. The system (1) according to any one of claims 1 to 12, comprising a pressure device (42) constructed 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 any one of claims 1 to 13, wherein the FO membrane (6c) purifies water received on the feed side (6a) into the purified water.

15. 1. A method of operating a system (1) for producing a peritoneal dialysis fluid (PD) comprising a forward osmosis FO unit (6) including a draw side (6a) and a feed side (6b) separated by a FO membrane (6c), the FO unit (6) configured to receive one or more PD concentrate fluids (4a, 4b) 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 an osmotic pressure gradient between the draw side (6a) and the feed side (6b) to dilute the one or more PD concentrate fluids into a diluted PD concentrate fluid, the method comprising: A fluid path (2) of the system (1) directs the water to the feed side (6b) of the FO unit (6) (S3); the fluid pathway (2) of the system (1) directing (S4) the one or more PD concentrate streams (4a, 4b) to the draw side (6a) of the FO unit (6); A concentration sensor (51) of the system (1) detects the concentration of the diluted PD concentrate fluid (S5); The fluid path (2) of the system (1) directs the diluted PD concentrate fluid to a container (9) (S6); a control device (10) of the system (1) controlling (S7) a degree of dilution of the one or more PD concentrate fluids during production of a diluted PD concentrate fluid based on the sensed concentrations by recirculating the diluted PD concentrate fluid in a first recirculation path (61) including the draw side (6a) of the FO unit (6) and the vessel (9) such that one or more predetermined criteria are met; A method of operation comprising:

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