System for delivering medical fluids for renal replacement therapy and method of operating such a system - Patents.com

Abstract

The system comprises a first device (10) and a second device (30) connected to establish a fluid pathway (21) between a pump (15) in the first device (10) and a container (38) in the second device (30) through a valve (32) of the second device (30). A control unit (31) in the second device (30) selectively operates the valve (32) to open the fluid pathway (21). The second device (30) is configured to supply a medical fluid for renal replacement therapy by use of a first fluid (F1) received from the first device in the fluid pathway (21). A control unit (11) in the first device (10) directly or indirectly measures the fluid pressure in the fluid path (21) and is operative to intermittently operate the pump (15) to pump the first fluid (F1) through the fluid path (21) during operation of the second device (30) and to stop the pump (15) when the fluid pressure in the fluid path (21) indicates that the valve (32) is closed, thereby allowing the first device (30) to operate to refill the container (38) without synchronization with the second device (30).

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to the field of renal replacement therapy, and in particular to the delivery of medical fluids for use in such therapy. [Background technology]

[0002] Renal replacement therapy (RRT) is a therapy that replaces the normal hemofiltration function of the kidneys. It is used when the kidneys are not functioning adequately, including acute kidney injury and chronic kidney disease, known as renal failure. RRT involves the removal of solutes from the blood of patients suffering from renal failure, for example, by dialysis (hemodialysis (HD) or peritoneal dialysis (PD)), hemofiltration, or hemodiafiltration. Depending on the modality, RRT can be performed manually or with the use of a machine.

[0003] In RRT, one or more medical fluids of specific composition are used for the treatment of the blood. Such medical fluids include the so-called dialysis fluids and replacement fluids.

[0004] Medical fluids for RRT may be produced by mixing one or more fluids, e.g., one or more concentrates, with water. In some installations, a separate water preparation device is configured to receive and process tap water to produce water of sufficient purity and quality, e.g., by reverse osmosis (RO). The water preparation device is configured to pump purified water to a fluid generation device that mixes the concentrates, on demand. The fluid generation device may or may not be integrated into the dialysis machine. Dedicated communication interfaces are provided on the water preparation device and the fluid generation device to allow the devices to synchronize their operation, e.g., by exchanging synchronization signals. Such communication interfaces add cost to the water preparation device and the fluid generation device and reduce interoperability between different manufacturers and between older and newer equipment.

[0005] US Patent Application Publication No. 2019 / 0262522 addresses this issue with respect to a fluid generating device configured to generate dialysate for PD by using purified water from a separate water source. US Patent Application Publication No. 2019 / 0262522 proposes providing separate pumps for the water source and the fluid generating device and installing water lines between the water source and the fluid generating device to establish fluid communication between the pumps. The fluid generating device operates its pump independently of the pump in the water source. In one of the many proposed implementations, the water source provides automatic demand control by being configured to continuously monitor the pressure in the water line and control its pump to supply purified water according to the monitored pressure. A similar solution is proposed in US Patent Application Publication No. 2010 / 0018923. One drawback of these proposals is that the water source needs to be actively controlled at all times during operation of the fluid generating device. This leads to increased power consumption and may also lead to significant mechanical wear of the water source and the pump in the fluid generating device over time.

[0006] The aforementioned technical challenges are equally applicable to the transfer of medical fluids from a fluid generating device to an RRT machine that is physically separated from the fluid generating device. Summary of the Invention

[0007] It is an object to at least partially overcome one or more limitations of the prior art.

[0008] A further object is to provide a system for delivering medical fluid for use in RRT while mitigating the need for synchronization between a first device that provides a first fluid and a second device that provides the medical fluid through use of the first fluid.

[0009] Another objective is to reduce power consumption and / or improve the robustness of such a system for delivering medical fluids.

[0010] One or more of these objects, as well as further objects that may become apparent from the following description, are at least partly achieved by a system for producing a medical fluid, a system for handling spent medical fluids and a method according to the independent claims, embodiments of which are defined by the dependent claims.

[0011] A first aspect is a system for supplying a medical fluid for renal replacement therapy. The system comprises a first device configured to provide a first fluid. The first device comprises a fluid pump and a first control unit. The system further comprises a second device configured to supply the medical fluid by use of the first fluid. The second device comprises a container, a control valve, and a second control unit. The first and second devices are connected to establish a fluid path between the fluid pump in the first device and the container in the second device through the control valve. The second control unit is configured to selectively operate the control valve to open the fluid path. The first control unit is connected to a sensor arrangement configured to measure a parameter indicative of fluid pressure in the fluid path. The first control unit is configured to operate the fluid pump to pump the first fluid into the fluid path intermittently and independently of the parameter during operation of the second device, and to stop the fluid pump when the parameter indicates that the control valve is closed.

[0012] A second aspect is a method performed by a first device in fluid communication with a second device that delivers a medical fluid for renal replacement therapy through the use of the first fluid, the method including intermittently operating a fluid pump in the first device to pump the first fluid through a control valve in the second device and on a fluid pathway extending between the fluid pump in the first device and a container in the second device while the second device is operating to deliver the medical fluid, obtaining a measurement of a parameter indicative of fluid pressure in the fluid pathway from a sensor arrangement, and stopping the fluid pump when the parameter indicates that the control valve is closed.

[0013] The first and second aspects apply a trial and error approach to operate the first device, which allows the first device to operate independently of the second device, while still ensuring that the reservoir in the second device is properly and timely refilled with the first fluid from the first device. Furthermore, by only operating the fluid pump in the first device intermittently, the life of the fluid pump can be extended and its power consumption can be reduced. Furthermore, by having a control valve in the second device to selectively open and close the fluid path between the first device and the second device, it is possible to omit the pump in the second device to draw fluid from the first device. This reduces costs, saves power, and increases the robustness of the system.

[0014] The first and second aspects are applicable to a second device configured to generate a medical fluid by processing a first fluid from a first device, for example by adding one or more compounds to the first fluid, and to supply the medical fluid for use in an RRT. The first and second aspects are equally applicable to a first device that provides a medical fluid to a second device configured to supply a medical fluid for use in an RRT, where the second device does not need to process the first fluid to generate the medical fluid, as the first fluid constitutes the medical fluid.

[0015] A third aspect is a system for handling spent medical fluid from a renal replacement therapy. The system comprises a first device comprising a fluid pump and a first control unit. The system further comprises a second device comprising a container configured to collect spent medical fluid, a control valve, and a second control unit. The first and second devices are connected to establish a fluid path between the fluid pump in the first device and the container in the second device through the control valve. The second control unit is configured to selectively operate the control valve to open the fluid path. The first control unit is connected to a sensor arrangement configured to measure a parameter indicative of fluid pressure in the fluid path. The first control unit is configured to intermittently and independently of the parameter operate the fluid pump to draw spent medical fluid from the fluid path and stop the fluid pump when the parameter indicates that the control valve is closed.

[0016] A fourth aspect is a method performed by a first device in fluid communication with a second device providing spent medical fluid from a renal replacement therapy, the method including intermittently operating a fluid pump in the first device to draw spent medical fluid through a control valve in the second device onto a fluid pathway extending between the fluid pump in the first device and the container in the second device while the second device is operating to collect the spent medical fluid in a container in the second device, obtaining measurements of a parameter indicative of fluid pressure in the fluid pathway from a sensor arrangement, and stopping the fluid pump when the parameter indicates that the control valve is closed.

[0017] The third and fourth aspects share technical advantages with the first and second aspects, such as the first device being capable of operating independently of the second device, extending the life of the fluid pump, and reducing power consumption through intermittent activation of the fluid pump.

[0018] A fifth aspect is a computer readable medium comprising program instructions which, when executed by a processor, cause the processor to perform a method of the second or fourth aspect.

[0019] Further objects, aspects and advantages, as well as features and embodiments, may become apparent from the following detailed description, the appended claims, and the drawings. [Brief description of the drawings]

[0020] [Figure 1A] , [Figure 1B] FIG. 1 is a schematic diagram of an exemplary system according to a first and second embodiment. [Figure 1C] FIG. 2 is a schematic diagram of a control unit in the system of FIGS. 1A-1B. [Figure 2A] 1A is a flowchart of an exemplary method for controlling a first device in the system of FIGS. 1A-1B. [Figure 2B] , [Figure 2C] 1C is a flowchart of an exemplary method for controlling a second device in the system of FIGS. 1A-1B. [Figure 2D] 1A is a flow chart of an exemplary method of installation and start-up of the system of FIGS. 1A-1B. [Figure 2E] , [Figure 2F] FIG. 13 is a timing diagram of a fluid transfer attempt by a first device and a fluid introduction by a second device according to an embodiment. [Figure 3A] , [Figure 3B] 1A-1B is a flowchart of an exemplary method of controlling a first device in the system of FIGS. 1A-1B to supply a first fluid to a second device and receive spent medical fluid from the second device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all, embodiments are shown. Indeed, the subject matter of this disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, but rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.

[0022] It will also be understood that, where possible, any of the advantages, features, functions, devices, and / or operational aspects of any embodiment described and / or contemplated herein may be included in any of the other embodiments described and / or contemplated herein, and / or vice versa. Furthermore, unless expressly stated otherwise, where possible, any term expressed in the singular herein is meant to include the plural, and / or vice versa. As used herein, "at least one" means "one or more," and these phrases are intended to be interchangeable. Thus, the terms "a" and / or "an" shall mean "at least one" or "one or more," although the phrases "one or more" or "at least one" are also used herein. As used herein, unless the context otherwise requires to express the language or necessary implication, the word "comprises," or variations such as "comprises" or "comprising," are used in an inclusive sense, i.e., to specify the presence of the stated features, but not to preclude the presence or addition of additional features in various embodiments.

[0023] It will be further understood that although terms such as first, second, etc. may be used herein to describe various elements, these elements should not be limited to these terms. These terms are used only to distinguish one element from another. For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element, without departing from the scope of the present disclosure. As used herein, the terms "multiple," "plural," and "plurality" are intended to imply the provision of two or more elements. The term "and / or" includes any and all combinations of one or more of the associated listed elements.

[0024] For the sake of brevity and / or clarity, well-known functions or constructions may not be described in detail.Unless otherwise specified, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0025] The embodiments relate to a system for providing a medical fluid for use in renal replacement therapy (RRT). The system comprises a first device and a second device. The first device is configured to provide a first fluid to the second device through a fluid pathway extending between the first device and the second device. The second device is configured to provide a medical fluid for use in RRT based on the first fluid. The second device may or may not also be configured to perform RRT by use of the medical fluid. In other words, the second device may be an RRT machine, for example a dialysis machine. The embodiments described herein contemplate that the second device comprises a container configured to receive a first fluid flowing from the first device on the fluid pathway, and the second device gradually consumes the first fluid in the container as it provides the medical fluid for use in RRT. As the first fluid in the container is consumed, the second device needs to replenish the container by receiving the first fluid on the fluid pathway. The embodiments described herein further contemplate that the container in the second device is not continuously refilled, but rather the first fluid is only intermittently introduced into the container by the second device selectively opening an inlet valve, for example whenever the amount of the first fluid in the container reaches a predetermined minimum value.

[0026] The embodiments described below serve to allow a first device to be operated independently of a second device while still ensuring that the containers in the second device are properly and timely replenished.

[0027] In some embodiments, this technical effect is achieved by providing the first device with a sensor arrangement configured to directly or indirectly measure the fluid pressure in the fluid pathway between the first device and the second device, and by appropriately configuring a control unit of the first device to operate based on the fluid pressure measured by the sensor arrangement. Specifically, the control unit is configured to intermittently operate a fluid pump ("feed pump") in the first device to pump the first fluid into the fluid pathway during operation of the second device, and to stop the fluid pump when the fluid pressure in the fluid pathway indicates that the inlet valve of the second device is closed. Thus, in these embodiments, the first device applies a trial and error (TAE) approach by repeatedly attempting to push the first fluid on the fluid pathway into a container of the second device. These attempts are made independently of the fluid pressure in the fluid pathway, for example according to a predetermined time schedule. If such an attempt closes the inlet valve of the second device, the fluid pressure in the fluid pathway will rapidly increase, assuming that the first fluid is an incompressible liquid. The increase in fluid pressure is detected by the first device, thereby terminating the trial. In such a trial, if the inlet valve on the second device is open, the first device continues to pump the first fluid into the reservoir of the second device according to a predefined setting or until the second device closes the inlet valve. The TAE approach allows the first device to operate independently of the second device while allowing the reservoir in the second device to be timely replenished with the first fluid from the first device. At the same time, the intermittent activation limits power consumption. Furthermore, for at least some types of fluid pumps, the intermittent operation limits wear compared to continuous operation.

[0028] As mentioned above, the fluid transfer attempts are triggered independently of the fluid pressure in the fluid path between the first and second devices. In some embodiments, the time interval between fluid transfer attempts by the first device may be set in relation to the expected time difference between refills of the container in the second device ("refill interval") and / or the expected time from the opening of the inlet valve to complete depletion of the container ("time to depletion"). For example, the second device may have a maximum (maximum possible) delivery rate of medical fluid by design. The maximum delivery rate of medical fluid corresponds to the maximum consumption rate of the first fluid in the container and thus corresponds to the minimum (minimum possible) refill interval. Similarly, the maximum delivery rate corresponds to the minimum time to depletion, given by the remaining amount of the first fluid in the container when the inlet valve is open divided by the maximum consumption rate. Examples of criteria for setting the time interval between fluid transfer attempts are given below with reference to Figures 2E-2F.

[0029] The TEA approach may be applied in a similar manner when the first device is configured to receive a fluid ("second fluid") from the second device on a second fluid path. As in the previous embodiment, it is envisaged that the second device comprises a container for collecting the second fluid and an outlet valve that is intermittently opened to establish fluid communication between the container and the second fluid path. To enable the TEA approach, the first device has a sensor arrangement configured to directly or indirectly measure the fluid pressure in the second fluid path, and the control unit of the first device is configured to operate based on this fluid pressure. Specifically, in some embodiments, the control unit is configured to intermittently activate a fluid pump ("exhaust pump") in the first device to draw the second fluid into the second fluid path during operation of the second device, and to stop the fluid pump when the fluid pressure in the second fluid path indicates that the outlet value of the second device is closed. Thus, the first device repeatedly attempts to draw the second fluid from the second device onto the second fluid path. These attempts are made independently of the fluid pressure in the second fluid path, for example according to a predetermined time schedule. In some embodiments, the second fluid is spent medical fluid that is produced when the above-mentioned medical fluid is used in the RRT. The first device may be configured to direct the incoming spent medical fluid to a drain or to collect the spent medical fluid in a container associated with the first device. In another alternative, the first device may be configured to generate ("regenerate") medical fluid from the spent medical fluid.

[0030] The embodiments are applicable to any type of RRT, including but not limited to hemodialysis, hemofiltration, hemodiafiltration, and peritoneal dialysis.

[0031] In some embodiments, the second device is a dialysis machine for hemodialysis, hemofiltration or hemodiafiltration. Such a dialysis machine may be dedicated to the treatment of patients with acute kidney injury (AKI), commonly known as "acute dialysis". The treatment of AKI by hemodialysis is typically performed continuously by the so-called continuous renal replacement therapy (CRRT). Dialysis machines for acute dialysis generally comprise a scale on which containers or "fluid bags" are removably placed. The operation of the dialysis machine is controlled based on the weight of the fluid bags given by the readings of the scale. Generally, at least one of the fluid bags is configured to hold the dialysate used in the dialysis treatment, and at least one of the fluid bags is configured to receive the spent dialysate. As is well known to those skilled in the art, dialysis treatment involves the extraction of excess fluid from the patient, commonly known as "ultrafiltrate". The ultrafiltrate is included in the spent dialysate. The amount and extraction rate of ultrafiltrate extracted from the patient are important treatment parameters during dialysis. During operation, the dialysis machine calculates and monitors these treatment parameters based on the readings of the scale, which represent the weight of the fluid bags.

[0032] Traditionally, dialysate for acute dialysis is provided in pre-filled fluid bags that are suspended on one or more scales of the dialysis machine. Acute dialysis therefore places a burden on the caregiver, who must repeatedly exchange emptied fluid bags for new filled fluid bags. An alternative may be to generate dialysate on-site.

[0033] In one proposal, the dialysis machine is configured to receive dialysate from a separate fluid preparation device, which may be configured to prepare the dialysate from tap water or purified water. Thereby, an empty fluid bag on the scale of an existing dialysis machine for acute dialysis may be connected to receive the dialysate from the fluid preparation device. This fluid bag may need to be refilled or refilled with dialysate during operation of the dialysis machine. However, the process of refilling the fluid bag may affect the operation of the dialysis machine and therefore should be performed infrequently during a limited period of time. With reference to the above discussion of the first and second devices, it is understood that the first device may be a fluid preparation device and the second device may be a dialysis machine. A corresponding implementation example is described below with reference to FIG. 1B.

[0034] In another proposal, the dialysis machine can generate dialysis fluid from purified water, for example by mixing one or more concentrates or substances with the purified water. The purified water may be received from a separate water purification device, which may be configured to process tap water into purified water. In the example of a dialysis machine for acute dialysis, the purified water may be received in a fluid bag on the scale of the dialysis machine, and the mixing may take place in this fluid bag and / or downstream thereof. As in the previous proposal, it may be desirable to perform refilling of the fluid bag infrequently during a limited period of time. Thus, the first device may be a water preparation device and the second device may be a dialysis machine. A corresponding implementation example is described below with reference to FIG. 1A.

[0035] FIG. 1A illustrates a schematic diagram of a treatment system 1 including a water preparation device (WPD) 10 ("first device") and an RRT machine 30 ("second device") connected for fluid communication. A control unit 11 is configured to control the operation of the WPD 10, and a control unit 31 is configured to control the operation of the RRT machine 30. The WPD 10 comprises a water treatment unit 12, a connector 13 for connecting the WPD 10 to a source of tap water 40, an inlet valve 14, a supply pump 15, a first pressure sensor 16, a discharge pump 17, and a second pressure sensor 18. The control unit 11 is operable to open the inlet valve 14 to introduce tap water F0 from the source 40 into the water treatment unit 12, which is configured to treat the tap water into purified water suitable for dialysis. The water treatment unit 12 may be of conventional construction and may perform one or more of heating, filtration, softening, reverse osmosis (RO), deionization (DI), UV irradiation, distillation, and the like. Purified water may thereby be produced to meet both chemical purity and microbiological and endotoxin purity thresholds. Supply pump 15 is configured to pump purified water F1 over a first fluid path ("supply path") 21 to the RRT machine 30, and pressure sensor 16 is configured to measure fluid pressure in supply path 21. In the illustrated example, WPD 10 is also configured to receive spent dialysate F2 from the RRT machine 30 over a second fluid path ("exhaust path") 22. Fluid paths 21, 22 may be defined by flexible tubing and / or channels within the cassette and may be permanently or removably connected to WPD 10 and RRT machine 30. Exhaust pump 17 is configured to pump spent dialysate from exhaust path 22 to a drain 19 or to a container (not shown), and pressure sensor 18 is configured to measure fluid pressure in exhaust path 22. It can be seen that pressure sensors 16, 18 define a pressure sensor configuration within WPD 10.

[0036] 1A, the source 40 is configured to provide at least partially purified water. In such an alternative, the water treatment unit 12 may be simplified or even omitted.

[0037] The RRT machine 30 comprises an inlet valve 32, an outlet valve 33, a first scale 34, a second scale 35, a fluid generation unit 36, a treatment unit 37, a first fluid bag 38, and a second fluid bag 39. The first fluid bag 38 is disposed on the scale 34, and the second fluid bag 39 is disposed on the second scale 35. The control unit 31 is operable to open the inlet valve 32 to introduce purified water F1 from the WPD 10 on the supply path 21 into the fluid bag 38 for intermediate storage. The purified water F1 is transferred from the fluid bag 38 to the fluid generation unit 36, which is configured to generate dialysate F2′ from the purified water F1. As mentioned above, the fluid generation unit 36 ​​may be configured to mix one or more concentrates or substances (powders or liquids) with the purified water to form the dialysate. The dialysate F2′ is supplied to a treatment unit 37, which is configured to perform dialysis treatment of the blood of a patient (not shown). The treatment unit 37 is configured to transfer the spent dialysate F2 to a fluid bag 39 for intermediate storage. In some embodiments, the readings on the scale 34 are used by the control unit 31 to determine the amount of dialysate F2′ to be delivered to the treatment unit 37, and the readings on the scale 35 are used by the control unit 31 to determine the amount of spent dialysate F2 provided by the dialysis treatment for calculation of one or more treatment parameters related to ultrafiltration. The control unit 31 is operable to open the outlet valve 33 to allow the spent dialysate F2 to be drawn into the WPD 10 at the drain path 22. Such dialysis treatments are well known to those skilled in the art and will not be described herein. Those skilled in the art will also appreciate that the RRT machine 30 may be formed in part by disposable items that are discarded after the dialysis treatment. Such disposable items may include the fluid bags 38, 39, at least a portion of the fluid generation unit 36, and at least a portion of the treatment unit 37. For example, it is conventional practice for disposable line sets and disposable dialyzers to be installed in the RRT machine 30 to define the dialysate circuit and the extracorporeal blood circuit within the treatment unit 37.It should also be noted that the pressure sensors 16, 18 may be included in the disposable item and may be connected for signal transmission to the WPD10 when the disposable item is installed. The disposable item may also include fluid paths 21, 22. In some embodiments, the valves 32, 33 are pinch valves.

[0038] Figure 1B is a schematic illustration of a treatment system 1 including a fluid preparation device (FPD) 30A ("first device") and an RRT machine 30B ("second device") connected for fluid communication. The FPD 30A is configured to generate dialysis fluid F1 and supply it to the RRT machine 30, and receive spent dialysis fluid F2 from the RRT machine 30. The following description focuses on the differences from the system of Figure 1A. The FPD 30A is mainly similar to the WPD 10 in that it includes a control unit 11, a connector 13, an inlet valve 14, a supply pump 15, a first pressure sensor 16, a discharge pump 17, and a second pressure sensor 18. However, compared to the WPD 10, the FPD 30A is connected by a connector 13 to a source 10 of purified water F0 and includes a fluid generation unit 36 configured to generate dialysis fluid F1. The fluid generation unit 36 may correspond to the fluid generation unit 36 in the RRT machine 30 of Figure 1A, but may have a different structure. Generally, the fluid generation unit 36 in the FPD 30A may be configured to mix one or more concentrates or substances with purified water F0 to form dialysis fluid F1.

[0039] The RRT machine 30B is similar to the RRT machine 30 of FIG. 1A in that it mainly comprises a control unit 31, an inlet valve 32, an outlet valve 33, a first scale 34, a second scale 35, a treatment unit 37, a first fluid bag 38, and a second fluid bag 39. However, the RRT machine 30B does not have a functional equivalent to the fluid generation unit 36. The control unit 31 is operable to open the inlet valve 32 to introduce dialysate F1 from the FPD 30A on the supply path 21 into the fluid bag 38 for intermediate storage. The dialysate F1 is transferred from the fluid bag 38 to the treatment unit 37, which may be identical to the treatment unit 37 of FIG. 1A. The treatment unit 37 is configured to transfer spent dialysate F2 to the fluid bag 39 for intermediate storage. In some embodiments, the readings on scale 34 are used by the control unit 31 to determine the amount of dialysate F1 to be delivered to the processing unit 37, and the readings on scale 35 are used by the control unit 31 to determine the amount of spent dialysate F2 provided by the dialysis treatment for calculation of one or more treatment parameters related to ultrafiltration. The control unit 31 is operable to open the outlet valve 33 to allow spent dialysate F2 to be drawn into the FPD 30A at the drain path 22.

[0040] FIG. 1C is a schematic block diagram of each of the control units 11, 31 of FIG. 1A-FIG. 1B. The control units 11, 31 are configured to generate control signals Ci for controlling the operation of the first / second devices according to a control program including computer instructions. The control program may also be configured to operate based on input signals Si received by the control units 11, 31. In the WPD 10, the control unit 11 may be connected to provide control signals for the valves 14, the water treatment unit 12, and the pumps 15, 17, and to receive input signals from the pressure sensors 16, 18. In the RRT machine 30, the control unit 31 may be connected to provide control signals for the valves 32, 33, the fluid generation unit 36, and the treatment unit 37, and to receive input signals from the scales 34, 35. In the FPD 30A, the control unit 11 may be connected to provide control signals for the valves 14, the fluid generation unit 36, and the pumps 15, 17, and to receive input signals from the pressure sensors 16, 18. In the RRT machine 30B, the control unit 31 may be connected to provide control signals for the valves 32, 33 and the treatment unit 37, and to receive input signals from the scales 34, 35. The above are merely simplified examples, and each control unit 11, 31 may be configured to generate further control signals Ci and receive further input signals Si, as will be readily understood by those skilled in the art.

[0041] Each control unit 11, 31 comprises a processor 51 and a computer memory 52. ​​A control program is stored in the memory 52 and executed by the processor 51. The control program may be provided to the control unit 11, 31 on a computer readable medium, which may be a tangible (non-transitory) product (e.g., a magnetic medium, an optical disk, a read-only memory, a flash memory, etc.), or by a propagated signal. In the illustrated example, the control unit 11, 31 comprises a signal interface 53A for providing control signals Ci and receiving input signals Si. In the illustrated example, the control unit 11, 31 also comprises an input interface 53B for connecting to one or more input devices 54 that allow an operator to input control data, and an output interface 53C for connecting to one or more output devices 55 for providing feedback data to the operator. For example, the input device 54 may comprise a keyboard, a keypad, a computer mouse, a control button, a touch screen, a printer, a microphone, etc., and the output device 55 may comprise a display device, a touch screen, an indicator lamp, an alarm device, a speaker, etc.

[0042] FIG. 2A is a flow chart of a method 200 for controlling the first device 10, 30A in the system 1 shown in FIG. 1A and FIG. 1B. The method 200 may be executed by the control unit 11. In step 201, the supply pump 15 is intermittently operated to pump the fluid F1 provided by the first device 10, 30A into the supply path 21 and towards the second device 30, 30B. Step 202 is executed during step 201 and includes measuring the fluid pressure in the supply path 21, for example in a measurement signal from the pressure sensor 16. In step 203, the supply pump 15 is stopped when the fluid pressure indicates that the inlet valve 32 of the second device 30, 30B is closed, for example when the fluid pressure exceeds a limit value. Thereby, the first device 10, 30A implements the above-mentioned TAE approach to provide the fluid F1 to the second device 30, 30B.

[0043] It is understood that if the inlet valve 32 is open when the feed pump 15 is activated by step 201, the fluid F1 is pumped into the container 38. In some embodiments, the feed pump 15 remains activated until the measured fluid pressure indicates that the inlet valve 32 is closed. It is also contemplated to control the activation based on a predefined setting, for example a maximum limit for the duration of the activation of the feed pump 15, or the amount of fluid pumped during the activation. For example, the feed pump 15 may be automatically stopped if such a maximum limit is exceeded, even if the fluid pressure indicates that the inlet valve 32 is still open. Such an automatic stop may indicate an operation error in the first or second device, and the first device may generate a warning or alarm for the operator, for example on the output device 55 of FIG. 1C.

[0044] The pump 15 may need to be stopped quickly by step 203 to avoid a build-up of excessive fluid pressure potentially causing leakage in the supply path 21 or its connections to the first and second devices if the inlet valve 32 is closed when the pump 15 is actuated. To mitigate the risk of excessive fluid pressure and allow for the use of a simpler pump 15, a compliant arrangement 23 may be placed in fluid communication with the supply path 21, as illustrated in FIGS. 1A-1B. The compliant arrangement 23 is configured to absorb a portion of the pressure increase in the supply path 21. The compliant arrangement 23 may be an expandable tube section or a chamber placed anywhere between the supply pump 15 and the inlet valve 32. Alternatively or additionally, the compliant arrangement 23 may be included in the pump 15. For example, the pump 15 may be configured to leak fluid in the opposite direction to the pumping direction (known as "backslip") if pressure increases downstream of the pump 15. In some embodiments, the pump 15 has a selected characteristic of backslip as a function of pressure. Non-limiting examples include peristaltic pumps or gear pumps configured to have a selected degree of occlusion. Alternatively or additionally, the build-up of excess fluid pressure in the supply line 21 is mitigated by configuring the inlet valve 32 to have a soft-close feature. The soft-close feature may be implemented by operating and / or configuring the inlet valve 32 to close slowly. In this context, "slowly" implies that the response time of the inlet valve 32 is controlled in relation to the stop transition time of the pump 15 to ensure that the fluid pressure in the supply line 21 falls below a limit inherent in the design of the supply line 15. The response time is the time it takes to switch the inlet valve 32 from a fully open state to a fully closed state, and the stop transition time is the time it takes to stop the pump 15 during operation. In some embodiments, the inlet valve 32 has a response time of 1 to 10 seconds.

[0045] In some embodiments, the pressure sensor 16 is or comprises a pressure switch configured to indicate when the fluid pressure exceeds a configurable limit pressure. Step 203 may infer the state of the inlet valve 32 from a signal generated by the pressure switch (see Si in FIG. 1C). The presence of an indication in the signal implies that the inlet valve 32 is closed, and the absence of an indication implies that the inlet valve 32 is open.

[0046] FIG. 2B is a flow chart of a method 210 for controlling the second device 30 in the system 1 of FIG. 1A. The method 210 may be executed by the control unit 31. In step 211, the fluid generating unit 36 ​​operates to generate dialysate F2′ from purified water F1 in the container 38 and to supply the dialysate F2′ to the treatment unit 37. In some embodiments, the step 211 may be configured for a so-called “online generation” of dialysate, which implies that the dialysate is generated at a rate that corresponds to the consumption of the dialysate by the treatment unit 37. In other words, the dialysate is generated on demand for use by the treatment unit 37. Step 212 is executed during step 211 and involves measuring the fill level in the container 38. In FIG. 1A, the fill level may be inferred from the weight measured by the scale 34. If the fill level is below a lower limit, step 213 opens the inlet valve 32. Step 213 may keep the inlet valve 32 open until the fill level in the container 38 reaches an upper limit value, after which the inlet valve 32 is closed and the container 38 is refilled with purified water F1. Since the first device 10 performs the method 200 while the second device 30 performs the method 210, the container 38 is refilled without synchronization between the first device 10 and the second device 30.

[0047] FIG. 2C is a flow chart of a method 210 for controlling the second device 30B in the system 1 of FIG. 1B. The method 210 may be performed by the control unit 31. In step 211′, the second device 30B operates to supply dialysate F1 from a container 38 to the treatment unit 37, which operates to perform a dialysis treatment. For example, the dialysate 31 may be drawn from the container 38 by a pump (not shown) in the treatment unit 37. Steps 212-213 of the method 210′ ​​may be identical to steps 212-213 of the method 210.

[0048] The first device 10, 30A may be controlled to obtain spent dialysate from the second device 30, 30B by a variant of the method 200 of Fig. 2A. Corresponding to step 201, the drain pump 17 is intermittently operated to draw fluid F2 from the second device 30, 30B in the drain path 22. Corresponding to step 202, the fluid pressure is measured in the drain path 22, for example in a measurement signal from the pressure sensor 18. Corresponding to step 203, the drain pump 17 is stopped when the fluid pressure indicates that the outlet valve 33 of the second device 30, 30B is closed, for example when the fluid pressure falls below a limit value. Thereby, the first device 10, 30A implements the above-mentioned TAE approach to obtain fluid F2 from the second device 30, 30B.

[0049] Similarly, the second device 30, 30B may be controlled by a variant of the method 210. Corresponding to step 212, the filling level in the container 39 is measured (see step 211) while a dialysis treatment is performed by the treatment unit 37. The filling level may be inferred from the weight measured by the scale 35. Corresponding to step 213, if the filling level exceeds an upper limit value, the outlet valve 33 is opened and a fluid communication between the container 39 and the drain path 22 is established.

[0050] FIG. 2D is a flow chart of a method 220 of setting up a dialysis treatment by using the first and second devices of FIGS. 1A-1B. In step 221, the first and second devices are connected by the installation of a supply path 21. In step 222, the first and second devices are connected by the installation of a drain path 22. For example, the paths 21, 22 may be defined in disposables that are installed in the first and second devices. In step 223, the first and second devices are started, and accordingly, the first device operates according to the method 200 and the second device operates according to the method 210 or 210′. Furthermore, the first device may operate according to the above-mentioned variant of the method 200 to remove spent dialysate from the second device, and the second device may operate according to the above-mentioned variant of the method 210 to selectively open the drain path 22.

[0051] 2E-2F show two examples of the timing of the actuation of the feed pump 15 in the first device and the opening of the inlet valve 32 in the second device.

[0052] In FIG. 2E, the supply pump 15 is actuated at regular time intervals Δ1 (see step 201 in FIG. 2A). Each actuation ("refill attempt") is represented as 231. Meanwhile, the inlet valve 32 is opened when the amount of fluid F1 in the container 38 falls below a lower limit (see step 213 in FIGS. 2B-2C), which may vary over time. In FIG. 2E, the periods during which the inlet valve 32 is open are represented by dashed lines 232. In the following, these periods will be referred to as "open periods". As can be seen in FIG. 2E, if an actuation 231 occurs during an open period 232, the actuation 231 will continue until the inlet valve 32 closes. As mentioned above, the second device may be associated with a minimum refill interval given by the constraints of the second device. In FIG. 2E, the minimum refill interval is represented by Δ2 min and the actual time difference between two successive open periods 232 is indicated as Δ1. To ensure the continuous operation of the second device, Δ1 may be set to be smaller than the aforementioned period until the depletion of the container 38. Furthermore, Δ1 is set to be smaller than Δ2. minFor example, Δ1 may be set to be smaller than Δ2 as illustrated in FIG. min It may be set so that there are multiple invocations 231 within the invocation.

[0053] In FIG. 2F, the first device postpones the next actuation 231 for a period Δ1′ during which the actuation resulted in refilling of the container 38. After Δ1′, the first device may resume actuation 231 of the supply pump at regular time intervals Δ1. The period Δ1′ is extended by Δ2 to ensure that no open period 232 occurs during Δ1′. min In one example, Δ1′ may be set relative to Δ2 min It is set so as not to exceed −Δ1.

[0054] 2F, the time interval Δ1 between actuations 231 may be varied according to any suitable function. In one example, the first device may decrease Δ1 over time until actuation 231 results in refilling of the container 38.

[0055] In a further variant, the control unit 11 of the first device 10, 30A is equipped with the functionality to adjust the time interval Δ1 between activations 231 based on the timing of the preceding open period 232. Thereby, the control unit 11 is configured to learn the operation of the second device 30, 30B, for example using a machine learning based functionality. The machine learning based functionality may be restarted for each treatment session or may be run continuously across multiple treatment sessions for the same or different patients.

[0056] In all the above examples, activation of the supply pump 15 is performed according to a time schedule that may be predetermined (including regular time intervals and / or variable time intervals according to a predetermined function) or may be dynamically determined by machine learning.

[0057] The timing diagrams of Figures 2E-2F and associated discussion, as well as the machine learning variations, are equally applicable to the operation of the discharge pump 17 and the opening of the outlet valve 33.

[0058] FIG. 3A is a flow chart of a further exemplary method 300 for controlling a first device to supply fluid to a second device. For clarity, the method 300 is described with reference to the system 1 of FIGS. 1A-1B. In step 301, the supply pump 15 is activated. In step 302, the fluid pressure in the supply line 21 is measured or monitored. If step 303 implies from the fluid pressure that the inlet valve 32 is closed, the method 300 proceeds to step 304, where the supply pump 15 is stopped. Then, step 305 stops the method 300 for a waiting period before proceeding to step 301, where the supply pump 15 is activated again. If step 303 implies from the fluid pressure that the inlet valve 32 is open, the method 300 may proceed to step 307, which may evaluate whether the maximum limit (time or amount) mentioned above has been exceeded. If the maximum limit has not been exceeded, step 307 proceeds to step 302, where the supply pump 15 remains activated. On the other hand, if the maximum limit is exceeded, step 307 proceeds to step 304, which stops the feed pump 15 and optionally interrupts the method 300 and generates a warning to the operator. In a variant, step 307 is omitted. As indicated by the dashed line, the method 300 may include a step 306, which increases the speed of the feed pump 15 over time according to any suitable function. Step 306 allows step 303 to detect that the inlet valve 32 is closed and to start the feed pump 15 at a low pumping speed to reduce the risk of excessive pressure building up in the feed line before the feed pump 15 is stopped after the stop by step 304. Returning to step 305, the waiting period may be a fixed period, for example to implement the regular time interval Δ1 of FIG. 2E. In a variant, step 305 may apply different waiting periods for different conditions. For example, if the container 38 is considered to be refilled, the waiting time may be set to Δ1′, and otherwise to Δ1.

[0059] FIG. 3B is a flow chart of a corresponding method 310 for controlling a first device to extract fluid from a second device. For clarity, the method 310 is described with reference to the system 1 of FIGS. 1A-1B. In step 311, the drain pump 17 is activated. In step 312, the fluid pressure in the drain line 22 is measured or monitored. If step 313 implies from the fluid pressure that the outlet valve 33 is closed, the method 310 proceeds to step 314, where the drain pump 17 is stopped. Step 315 then stops the method 310 for a waiting period before proceeding to step 311, where the drain pump 17 is activated again. Similar to step 305 of FIG. 3A, step 315 may use a fixed waiting period or may apply different waiting periods for different conditions. If step 313 implies from the fluid pressure that the outlet valve 33 is open, the method 310 may proceed to step 317, which may evaluate whether a maximum limit (time or amount) has been exceeded. If the maximum limit has not been exceeded, step 317 proceeds to step 312, where the discharge pump 17 remains activated. On the other hand, if the maximum limit has been exceeded, step 317 proceeds to step 314, which stops the discharge pump 17, and optionally aborts the method 310 and generates a warning to the operator. In a variant, step 317 is omitted. As indicated by the dashed line, method 310 may include step 316, which corresponds to step 306 of method 300, of increasing the speed of the discharge pump 17.

[0060] The system of Figures 1A-1B is given by way of example only. The embodiments are generally applicable to any system for supplying a medical fluid for use in RRT, where a first fluid of any type is pumped from a first device to a second device configured to supply the medical fluid based on the first fluid. The second device may be configured to perform the RRT, as in the system of Figures 1A-1B. Alternatively, the second device may be configured to supply the medical fluid to a separate device performing the RRT. The medical fluid may be any fluid consumed during RRT. For example, instead of a dialysate, the medical fluid may be a substitute fluid used in convection therapy such as hemofiltration or hemodiafiltration. It is understood that the first device is configured to supply the medical fluid in a quality suitable for its use during RRT.

[0061] Furthermore, the fill level of each container 38, 39 may be determined by other means than a scale, for example by a level sensor, which may be configured for continuous or point level sensing, including but not limited to an air pressure sensor, a conductivity sensor, a probe-based sensor, a float-based sensor, an optical sensor, or an ultrasonic sensor.

[0062] It should be noted that any type of sensor configuration may be provided to directly or indirectly sense the pressure in the fluid paths 21, 22. Thus, each pressure sensor disclosed herein may be replaced by another sensor configured to measure a parameter indicative of the fluid pressure. In one example, the fluid pressure in the fluid paths 21, 22 is indirectly given by a power consumption parameter of the respective pump 15, 17. For example, the power consumption parameter may represent the drive current and / or drive voltage of the pump 15, 17. In another example, for at least some types of pumps, the fluid pressure may be indirectly given by the speed of the pump 15, 17.

[0063] It should also be noted that the extraction of spent medical fluid from the second device by the first device may be omitted, for example, the spent medical fluid may be pumped directly to a drain or reservoir by the second device.

[0064] While the subject matter of this disclosure 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 subject matter of this disclosure is not limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and equivalents of the appended claims.

[0065] Below, a set of sections are recited to summarize certain aspects and embodiments of the invention disclosed above.

[0066] C1. A system for supplying a medical fluid (F2'; F1) for renal replacement therapy, said system comprising: a first device (10; 30A) configured to provide a first fluid (F1), said first device (10) comprising a fluid pump (15) and a first control unit (11); and a second device (30; 30B) configured to supply said medical fluid (F2'; F1) by use of said first fluid (F1), said second device (30; 30B) comprising a container (38), a control valve (32) and a second control unit (31), said first and second devices being connected to each other by a control valve (32) between said fluid pump (15) in said first device (10) and said second device (30; 30B). a first control unit (11) connected to a sensor arrangement (16, 18) configured to measure a parameter indicative of a fluid pressure in the fluid path (21), the first control unit (11) being configured to operate the fluid pump (15) to pump the first fluid (F1) into the fluid path (21) intermittently during operation of the second device (30; 30B) and independently of the parameter, and to stop the fluid pump (15) when the parameter indicates that the control valve (32) is closed. C2. The system described in C1, wherein the first control unit (11) is configured to operate the fluid pump (15) according to a time schedule. C3. A system as described in C1 or C2, wherein the first control unit (11) is configured to operate the fluid pump (15) at regular time intervals (Δ1). C4. A system as described in any one of C1 to C3, wherein the first control unit (11) is configured to separate successive operations of the fluid pump (15) by a time interval shorter than the predicted time of depletion of the container (38) when the fluid path (21) is opened by the second control unit (31). C5. The system according to any one of C1 to C4, wherein the first control unit (11) is configured to postpone the operation of the fluid pump for a waiting period (Δ1′) after the transfer of the first fluid (F1) into the container (38) by the first device (10; 30A), the waiting period (Δ1′) being equal to or greater than the expected time interval (Δ2′) between successive openings of the fluid path (21) by the second control unit (31). min ) is configured in relation to the system. C6. A system as described in any one of C1 to C5, wherein the second control unit (31) is configured to determine a filling level in the container (38) and to open the control valve (32) if the filling level is below a limit value. A system as described in C7.C6, wherein the second device (31) further comprises a scale (34) configured to measure a weight of the container (38), and the second control unit (31) is connected to the scale (34) and configured to determine the filling level based on the weight measured by the scale (34). C8. A system as described in any one of C1 to C7, wherein the first control unit (11) is configured to operate the fluid pump (15) according to a predetermined setting and / or until the parameter indicates that the control valve (32) is closed if, after actuating the fluid pump (15), the parameter indicates that the control valve (32) is open. C9. A system as described in any one of C1 to C8, wherein the first control unit (11) is configured to actuate the fluid pump (15) to operate at a first speed and, when a parameter indicates that the control valve (32) is open, to operate the fluid pump (15) at a second speed faster than the first speed. C10.A system as described in any one of C1 to C9, wherein the fluid path (21) includes a compliance arrangement (23) configured to absorb a portion of the increase in fluid pressure resulting from operation of the fluid pump (15) when the control valve (32) is closed. C11. A system as described in any one of C1 to C10, wherein the response time of the control valve (32) is controlled in relation to the stop transition time of the fluid pump (15) so as to maintain the fluid pressure below a limit value. C12. The system according to any one of claims C1 to C11, wherein the sensor arrangement (16, 18) comprises a pressure switch configured to send a signal when the fluid pressure exceeds a limit pressure. C13. A system according to any one of claims C1 to C12, wherein the first fluid (F1) is purified water. C14. A system according to any one of claims C1 to C12, wherein the first fluid (F1) is the medical fluid. C15. A system according to any one of claims C1 to C14, wherein the medical fluid (F2'; F1) is a dialysis fluid. C16. A system according to any one of claims C1 to C15, wherein the second device (30; 30B) is a dialysis machine. The system according to C17.C16, wherein the second device (30; 30B) is a dialysis machine for the treatment of acute kidney injury (AKI). The system according to any one of C18.C1 to C17, wherein the second device (30; 30B) comprises a second container (39) configured to hold a spent medical fluid (F2) and a second control valve (33), the first device (11) comprises a second fluid pump (17), the first and second devices (10, 30; 30A, 30B) are connected to establish a second fluid path (22) between the second fluid pump (17) in the first device (10) and the second container (39) in the second device (30; 30B) through the second control valve (33), and the second control unit (31) controls the second fluid path (22). the sensor arrangement (16, 18) is further configured to measure a further parameter indicative of a fluid pressure in the second fluid path (22), and the first control unit (11) is configured to operate the second fluid pump (17) to draw the spent medical fluid (F2) from the second fluid path (22) intermittently during operation of the second device (30; 30B) and independently of the further parameter, and to stop the second fluid pump (17) when the further parameter indicates that the second control valve (33) is closed. C19. A system for handling spent medical fluid (F2) from a renal replacement therapy, said system comprising a first device (10; 30A) comprising a fluid pump (17) and a first control unit (11), and a second device (30; 30B) comprising a container (39) configured to collect spent medical fluid (F2), a control valve (32) and a second control unit (31), said first and second devices (10, 30; 30A, 30B) establishing a fluid path (22) between said fluid pump (17) in said first device (10; 30A) and said container (39) in said second device (30; 30B) through said control valve (33). a first control unit (11) connected to a sensor arrangement (16, 18) configured to measure a parameter indicative of a fluid pressure in the fluid path (22), the first control unit (11) being configured to intermittently and independently of the parameter operate the fluid pump (17) to draw the spent medical fluid (F2) from the fluid path (22) and to stop the fluid pump (17) when the parameter indicates that the control valve (33) is closed. C20. A method performed by a first device (10; 30A) in fluid communication with a second device (30; 30B) for supplying a medical fluid (F2'; F1) for renal replacement therapy by use of a first fluid (F1), the method comprising: actuating (201) a fluid pump in the first device to pump the first fluid in a fluid path extending between the fluid pump in the first device and a container in the second device via a control valve in the second device intermittently while the second device is operating to supply the medical fluid; obtaining (202) a measurement of a parameter indicative of a fluid pressure in the fluid path from a sensor arrangement; and stopping (203) the fluid pump when the parameter indicates that the control valve is closed. C21. A method performed by a first device (10; 30A) in fluid communication with a second device (30; 30B) providing spent medical fluid (F2) from a renal replacement therapy, the method comprising: actuating (211) a fluid pump in the first device to draw the spent medical fluid through a control valve in the second device into a fluid pathway extending between the fluid pump in the first device and the container in the second device, intermittently while the second device is operating to collect the spent medical fluid in a container in the second device; obtaining (212) a measurement of a parameter indicative of fluid pressure in the fluid pathway from a sensor arrangement; and stopping (213) the fluid pump when the parameter indicates that the control valve is closed. C22. A computer readable medium comprising program instructions that, when executed by a processor (51), cause the processor (51) to perform the method of C20 or C21.

Claims

1. A system for supplying a medical fluid (F2'; F1) for renal replacement therapy, the system comprising: a first device (10; 30A) configured to provide a first fluid (F1), the first device (10) comprising a fluid pump (15) and a first control unit (11); a second device (30; 30B) configured to supply the medical fluid (F2'; F1) by use of the first fluid (F1), the second device (30; 30B) comprising a container (38), a control valve (32), and a second control unit (31); the first and second devices being connected to establish a fluid path (21) between the fluid pump (15) in the first device (10) and the container (38) in the second device (30; 30B) through the control valve (32); the second control unit (31) being configured to selectively operate the control valve (32) to open the fluid path (21); the first control unit (11) being connected to a sensor configuration (16, 18) configured to measure a parameter indicative of the fluid pressure in the fluid path (21); the first control unit (11) being configured to intermittently operate the fluid pump (15) to pump the first fluid (F1) into the fluid path (21) independently of the parameter during operation of the second device (30; 30B), and to stop the fluid pump (15) when the parameter indicates that the control valve (32) is closed.

2. The system according to claim 1, wherein the first control unit (11) is configured to operate the fluid pump (15) according to a time schedule.

3. The system according to claim 1, wherein the first control unit (11) is configured to operate the fluid pump (15) at regular time intervals (Δ1).

4. The system according to claim 1, wherein the first control unit (11) is configured to separate the continuous operation of the fluid pump (15) by a time interval shorter than the predicted depletion time of the container (38) when the fluid path (21) is opened by the second control unit (31).

5. The system according to claim 1, wherein the first control unit (11) is configured to delay the operation of the fluid pump during a waiting period (Δ1′) after the transfer of the first fluid (F1) into the container (38) by the first device (10; 30A), and the waiting period (Δ1′) is related to an expected time interval (Δ2 ｍｉｎ ) between successive openings of the fluid path (21) by the second control unit (31).

6. The system according to claim 1, wherein the second control unit (31) is configured to determine the filling level in the container (38) and to open the control valve (32) when the filling level is below a limit value.

7. The system according to claim 6, wherein the second device (30; 30B) further comprises a scale (34) configured to measure the weight of the container (38), and the second control unit (31) is connected to the scale (34) and is configured to determine the filling level based on the weight measured by the scale (34).

8. The system according to claim 1, wherein the first control unit (11) is configured to operate the fluid pump (15) according to a predetermined setting after operating the fluid pump (15) and when the parameter indicates that the control valve (32) is open, and / or until the parameter indicates that the control valve (32) is closed.

9. The system according to claim 1, wherein the first control unit (11) operates the fluid pump (15) to operate at a first speed, and when the parameter indicates that the control valve (32) is open, operates the fluid pump (15) at a second speed higher than the first speed.

10. The system according to claim 1, wherein the fluid path (21) comprises a compliance configuration (23) configured to absorb a part of the increase in the fluid pressure resulting from the operation of the fluid pump (15) when the control valve (32) is closed.

11. The system according to claim 1, wherein the response time of the control valve (32) is controlled in relation to the stop transition time of the fluid pump (15) so as to maintain the fluid pressure below a limit value.

12. The system according to claim 1, wherein the sensor arrangement (16, 18) comprises a pressure switch configured to transmit a signal when the fluid pressure exceeds a limit pressure.

13. The system according to claim 1, wherein the first fluid (F1) is purified water.

14. The system according to claim 1, wherein the first fluid (F1) is the medical fluid.

15. The system according to claim 1, wherein the medical fluid (F2′; F1) is dialysis fluid.

16. The system according to claim 1, wherein the second device (30; 30B) is a dialysis machine.

17. The system according to claim 16, wherein the second device (30; 30B) is a dialysis machine for the treatment of acute kidney injury (AKI).

18. The system according to claim 1, wherein the second device (30; 30B) comprises a second container (39) configured to hold the spent medical fluid (F2) and a second control valve (33), the first device (11) comprises a second fluid pump (17), the first and second devices (10, 30; 30A, 30B) are connected to establish a second fluid path (22) between the second fluid pump (17) in the first device (10) and the second container (39) in the second device (30; 30B) through the second control valve (33), the second control unit (31) is configured to selectively operate the second control valve (33) to open the second fluid path (22), the sensor arrangement (16, 18) is further configured to measure a further parameter indicative of the fluid pressure in the second fluid path (22), the first control unit (11) intermittently operates the second fluid pump (17) to draw the spent medical fluid (F2) from the second fluid path (22) independently of the further parameter during operation of the second device (30; 30B), and is configured to stop the second fluid pump (17) when the further parameter indicates that the second control valve (33) is closed.

19. A system for handling spent medical fluid (F2) from renal replacement therapy, said system comprising: a first device (10; 30A) comprising a fluid pump (17) and a first control unit (11); a second device (30; 30B) comprising a container (39) configured to collect spent medical fluid (F2), a control valve (32), and a second control unit (31); said first and second devices (10, 30; 30A, 30B) being connected so as to establish a fluid path (22) between said fluid pump (17) within said first device (10; 30A) and said container (39) within said second device (30; 30B) through said control valve (33); said second control unit (31) being configured to selectively operate said control valve (33) to open said fluid path (22); said first control unit (11) being connected to a sensor arrangement (16, 18) configured to measure a parameter indicative of the fluid pressure within said fluid path (22); said first control unit (11) being configured to intermittently operate said fluid pump (17) to draw spent medical fluid (F2) from said fluid path (22), independently of said parameter, and to stop said fluid pump (17) when said parameter indicates that said control valve (33) is closed. A system.

20. A method performed by a first device (10; 30A) in fluid communication with a second device (30; 30B) that supplies a medical fluid (F2′; F1) for renal replacement therapy by use of a first fluid (F1), said method comprising: operatively actuating said fluid pump within said first device to pump said first fluid through a fluid path extending between said fluid pump within said first device and a container within said second device via a control valve within said second device, intermittently while said second device is operating to supply said medical fluid (201); obtaining a measured value of a parameter indicative of the fluid pressure within said fluid path from a sensor arrangement (202); stopping said fluid pump when said parameter indicates that said control valve is closed (203). A method.

21. A method performed by a first device (10; 30A) in fluid communication with a second device (30; 30B) that provides spent medical fluid (F2) from renal replacement therapy, the method comprising: operating the fluid pump in the first device to draw the spent medical fluid into a fluid path extending between the fluid pump in the first device and the container in the second device through a control valve in the second device, intermittently while the second device is operating to collect the spent medical fluid in a container within the second device (211); obtaining a measured value of a parameter indicative of fluid pressure in the fluid path from a sensor configuration (212); stopping the fluid pump when the parameter indicates that the control valve is closed (213). **Claim 22** A program comprising instructions that, when executed by a processor (51), cause the processor (51) to execute the method according to claim 20 or 21.

Images