Control of fluid temperature in dialysis systems

Abstract

A dialysis system comprises a supply subsystem (4), a storage subsystem (5), a processing subsystem (6) and a control device (7). The supply subsystem (4) is arranged to supply a fluid to the storage subsystem (5) and comprises heating means (42) for heating the fluid. The storage subsystem (5) comprises a non-heated reservoir (50) for receiving the fluid from the supply subsystem (4). The treatment subsystem (6) is configured to obtain fluid from the storage subsystem (5) for dialysis treatment. The control device (7) operates the supply subsystem (4) to perform a series of fluid supply cycles to cause a series of time-separated doses of fluid to be supplied to the reservoir (50), each fluid supply cycle being dispensed with a target temperature and comprising a predefined number of doses. The supply subsystem (4) is operated to achieve a target temperature of the fluid in the reservoir (50) for the respective fluid supply cycle by a predefined number of doses.

Description

Technical Field

[0001] The present disclosure relates to the field of dialysis, and in particular, to a technique for controlling the temperature of a fluid in a reservoir of a dialysis system. Background Art

[0002] Renal replacement therapy (RRT) is a therapy that replaces the normal blood filtering function of the kidneys. This therapy is used when the kidneys are not functioning well, which is called renal failure and includes acute kidney injury (AKI) and chronic kidney disease (CKD). RRT involves the removal of water from the body of a patient with renal failure, as well as the exchange of solutes with the body. An example of RRT is extracorporeal blood therapy, in which blood circulates outside the patient's body and connects with one or more medical fluids. Modes of extracorporeal blood therapy include hemodialysis (HD), hemofiltration (HF), and hemodiafiltration (HDF). Another example of RRT is peritoneal dialysis (PD), in which a medical fluid is infused into the patient's peritoneal cavity to connect with the patient's blood through the peritoneum.

[0003] RRT is performed by a dialysis system formed by arranging one or more disposable components on a dialysis machine.

[0004] The medical fluid used in HD and PD is generally called dialysis fluid. In HF, the medical fluid is called replacement fluid, since it is infused into the patient's blood to replace the fluid removed during treatment. In HDF, both dialysis fluid and replacement fluid are used.

[0005] By using different types of dialysis machines, extracorporeal blood therapy of HD, HF or HDF treats AKI patients in different ways compared to CKD patients. Typically, AKI patients are treated continuously over a longer period of time and with a lower fluid flow rate compared to CKD patients. This continuous treatment is commonly referred to as CRRT (continuous renal replacement therapy). In order to ensure accurate and consistent monitoring and control of fluid removal, called ultrafiltration, AKI machines are usually provided with scales, which are used to measure the weight of fresh treatment fluid and the weight of used treatment fluid during treatment. CKD machines instead use flow meters or positive displacement pumps to control ultrafiltration.

[0006] The PD machine (also called a cycler) may include at least one scale to measure the weight of fresh treatment fluid infused into the peritoneal cavity and the weight of spent treatment fluid withdrawn from the peritoneal cavity. Alternatively, the cycler may use a positive displacement pump to control ultrafiltration.

[0007] In the case of AKI (e.g., CRRT), treatment fluids are conventionally supplied in bags provided by the manufacturer. The bags are typically stored at room temperature, so the treatment fluid will cool the patient's blood during treatment. This can result in hypothermia in the patient. Current mitigation measures are to preheat the bag, add an inline heater for the treatment fluid before contacting the blood, or add an inline heater to the extracorporeal blood circuit. This increases the complexity and cost of the AKI machine and / or increases the workload for the user.

[0008] These issues may also be relevant to other types of RRT, depending on the requirements and configuration of the dialysis system. Summary of the invention

[0009] One object is to at least partially overcome one or more limitations of the prior art.

[0010] Another object is to provide a technique for ensuring a consistent body temperature of a patient during RRT.

[0011] Another object is to provide a technique that is easily implemented in future dialysis systems as well as existing dialysis systems.

[0012] One or more of these objects, as well as other objects that may emerge from the following description, are at least partly achieved by a dialysis system according to the independent claims, embodiments of which are defined by the dependent claims.

[0013] A first aspect of the present disclosure is a dialysis system comprising: a supply subsystem configured to supply a fluid and comprising a heating device for heating the fluid; a storage subsystem comprising a non-heating reservoir, wherein the non-heating reservoir is fluidically connected to receive the fluid from the supply subsystem and is configured to accommodate an intermediate supply of the fluid during operation of the dialysis system; a processing subsystem configured to obtain the fluid from the storage subsystem and perform a dialysis treatment using the fluid; and a control device configured to operate the processing subsystem to perform the dialysis treatment. The control device is also configured to operate the supply subsystem to perform a series of fluid supply cycles to cause a series of time-spaced boluses of the fluid to be supplied to the non-heating reservoir, wherein a corresponding fluid supply cycle in the fluid supply cycle is assigned a target temperature and includes a predefined number of doses, wherein the supply subsystem is operated to achieve the target temperature of the fluid in the non-heating reservoir for the corresponding fluid supply cycle through the predefined number of doses.

[0014] The first aspect makes it possible to achieve the target temperature of the fluid in the reservoir without using a dedicated heating device (e.g., an electric heater) in or around the reservoir. Therefore, the reservoir is unheated. In the absence of appropriate countermeasures, the fluid stored in the non-heating reservoir will dissipate heat to the surrounding environment and gradually cool down. Therefore, the temperature of the fluid will change with the residence time of the fluid in the reservoir, and may eventually become too cold to be used for dialysis treatment. The aforementioned aspects relate to countermeasures for supplying dosed fluids that have been properly heated by the heating device in the supply subsystem to the non-heating reservoir. Supplying dosed heated fluids is a simple and effective technique for adjusting the temperature of the fluid in the non-heating reservoir. By stabilizing the fluid temperature at the target temperature, it is ensured that the patient's body temperature is consistent while performing dialysis treatment using the fluid in the non-heating reservoir. The dosage-based technology is applicable to any type of reservoir, whether it is a reservoir permanently installed in the storage subsystem or a disposable unit. Therefore, the first aspect is easy to implement on any existing dialysis system or future dialysis system.

[0015] In some embodiments, the target temperature is the temperature of the fluid in the non-heated reservoir at a target time point within the corresponding fluid supply cycle, or is a time average of the temperature of the fluid in the non-heated reservoir during the corresponding fluid supply cycle.

[0016] In some embodiments, the control device is configured to: obtain a target temperature; determine an energy content of a predefined number of doses to achieve the target temperature; and operate the supply subsystem to prepare a fluid portion for producing the predefined number of doses based on the energy content.

[0017] In some embodiments, the control device is configured to: determine a specified size of a corresponding dose and a specified temperature of the corresponding dose in a predefined number of doses, the specified size of the corresponding dose and the specified temperature of the corresponding dose making the predefined number of doses have the energy content; operate the supply subsystem to heat the fluid portion to the specified temperature by using a heating device; and operate the supply subsystem to produce a corresponding dose having a specified size from the fluid portion having the specified temperature.

[0018] In some embodiments, the control device is configured to: determine the amount of fluid removed from the non-heated reservoir by the processing subsystem during a corresponding fluid supply cycle; and determine the energy content of a predefined number of doses based in part on the amount of fluid removed from the non-heated reservoir.

[0019] In some embodiments, the control means is configured to determine the specified size of a respective dose based on an amount of said fluid removed from the non-heated reservoir during a respective fluid supply cycle.

[0020] In some embodiments, the control device is configured to determine a specified temperature for the respective dose based on a specified size for the respective dose to achieve an energy content of a predefined number of doses.

[0021] In some embodiments, the control device includes a computational model configured to: estimate the total energy loss of the fluid in the non-heating reservoir during the corresponding fluid supply cycle; and determine the energy content of a predefined number of doses based on the total energy loss during the corresponding fluid supply cycle.

[0022] In some embodiments, the total energy loss includes a first loss portion representing the dissipated heat energy of the fluid in the non-heating reservoir and a second loss portion representing the energy loss caused by the processing subsystem removing the fluid from the non-heating reservoir.

[0023] In some embodiments, the total energy loss also includes a third loss portion, which represents the dissipated thermal energy of the fluid in the flow path extending from the supply subsystem to the non-heating reservoir.

[0024] In some embodiments, the control device is capable of operating in a steady-state mode, in which the target temperature is the same for a plurality of consecutive fluid supply cycles, wherein the control device in the steady-state mode is configured to set the energy content of a predefined number of doses to be equal to the total energy loss during the corresponding fluid supply cycle.

[0025] In some embodiments, the computational model is configured to: calculate the instantaneous temperature of the fluid in the non-heated reservoir during a corresponding fluid supply cycle; and operate on the instantaneous temperature to determine the energy content of a predefined number of doses to achieve the target temperature.

[0026] In some embodiments, the control device is configured to obtain measurement values ​​indicating the instantaneous temperature of the fluid in the non-heated reservoir at a reference time point, and the calculation model is configured to calculate the instantaneous temperature of the fluid in the non-heated reservoir based on the measurement values.

[0027] In some embodiments, the control device is configured to: obtain an additional measurement value indicating the instantaneous temperature of the fluid in the non-heating reservoir at a time point after a reference time point; and adjust the calculated instantaneous temperature and / or calculation model at the time point based on the additional measurement value.

[0028] In some embodiments, the computational model is also configured to: calculate the instantaneous heat dissipation area of ​​the non-heating reservoir and / or the instantaneous amount of the fluid in the non-heating reservoir; and estimate the instantaneous temperature based on the instantaneous heat dissipation area and / or the instantaneous amount of the fluid in the non-heating reservoir.

[0029] In some embodiments, the control device is configured to obtain input data used by the computational model, wherein the input data indicates the duration of a corresponding fluid supply cycle, the specific timing of a corresponding dose within the corresponding fluid supply cycle, the duration of the corresponding dose, and the time curve of removing fluid from the non-heating reservoir during the corresponding fluid supply cycle.

[0030] In some embodiments, the control device is configured to determine the time profile based on an operational setting of the processing subsystem or a measured flow rate of the fluid entering the processing subsystem.

[0031] In some embodiments, wherein a respective dose is supplied to a non-heated reservoir during a dose period, the computational model comprises a function for estimating energy loss of the non-heated reservoir during the dose period, the function taking into account changes in energy loss caused by changes in temperature of the fluid in the non-heated reservoir resulting from supplying the respective dose.

[0032] In some embodiments, the control device is configured to operate the supply subsystem to perform a series of fluid supply cycles to cause the temperature of the fluid in the non-heated reservoir to drop by less than about 5°C, 4°C, 3°C, 2°C or 1°C between consecutive doses.

[0033] In some embodiments, the control device is configured to operate the supply subsystem to perform a corresponding fluid supply cycle having a duration greater than 5, 10, or 15 minutes and less than 30, 60, or 120 minutes.

[0034] In some embodiments, the non-heated reservoir is a disposable component.

[0035] In some embodiments, the dialysis system further comprises an environmental sensor arranged to measure an ambient temperature at the storage subsystem, and the control device is configured to determine the energy content of the predefined number of doses based on the ambient temperature.

[0036] In some embodiments, the storage subsystem comprises a scale for measuring the weight of the non-heated reservoir, and the control device is configured to cause the supply subsystem to supply the corresponding dose when the non-heated reservoir has a predefined weight measured by the scale.

[0037] In some embodiments, the control device is configured to perform open loop control on the supply subsystem to achieve the target temperature.

[0038] In some embodiments, the dialysis system further comprises a measuring device configured to measure a temperature value of the fluid in the non-heated reservoir corresponding to a target parameter, and the control device is configured to operate the supply subsystem to adjust the size of the corresponding dose and / or the temperature of the fluid to be supplied in the corresponding dose based on the difference between the target temperature and the measured temperature value.

[0039] In some embodiments, the fluid is a treatment fluid for a dialysis treatment.

[0040] In some embodiments, the fluid is water and the treatment subsystem includes a mixing device configured to mix the fluid with one or more concentrates to provide a treatment fluid for dialysis treatment.

[0041] A second aspect of the present disclosure is a control device included in a dialysis system according to the first aspect or any embodiment thereof.

[0042] A third aspect of the present disclosure is a computer-implemented method of operating a dialysis system, the dialysis system comprising a supply subsystem, a storage subsystem, and a processing subsystem. The method comprises: operating the processing subsystem to obtain fluid from a non-heated reservoir in the storage subsystem and performing a dialysis treatment using the fluid; and operating the supply subsystem to perform a series of fluid supply cycles to cause a series of time-spaced doses of the fluid to be supplied to the non-heated reservoir, wherein a corresponding fluid supply cycle in the fluid supply cycle is assigned a target temperature and includes a predefined number of doses, wherein the supply subsystem is operated to achieve the target temperature of the fluid in the non-heated reservoir for the corresponding fluid supply cycle through the predefined number of doses.

[0043] Any embodiment of the first aspect may be adapted as an embodiment of the third aspect.

[0044] A fourth aspect of the present disclosure is a computer-readable medium comprising computer instructions, which, when executed by a processing circuit, causes the processing circuit to perform the method of the third aspect or any embodiment thereof.

[0045] Other objects, aspects and embodiments as well as features and technical advantages will become apparent from the following detailed description, the appended claims and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1A is a schematic diagram of a dialysis system according to a first configuration example, and Figure 1B Shows Figure 1A The dialysis system in the invention implements hemodialysis through CRRT.

[0047] Figure 2A is a flow chart of an example method of controlling the temperature of a fluid in a reservoir of a dialysis system, and Figure 2B to Figure 2C An example of a fluid supply cycle is shown.

[0048] FIG. 3A to FIG. 3B respectively show the time curves of the fluid weight and the fluid temperature in the reservoir of the dialysis system during the method of FIG. 2 , and Figure 3C Another example of a time profile of the fluid temperature is shown.

[0049] Figure 4A Shown for Figure 2A The calculation parameters of the embodiment of the method are, FIG. 4B to FIG. 4E is a block diagram of a control circuit including an example computational model for estimating energy losses, and Figure 4F is used for Figure 2A A flow chart of an example control procedure of the method.

[0050] FIG. 5A to FIG. 5B Block diagrams of control structures with open-loop control and closed-loop control, respectively.

[0051] FIG. 6A to FIG. 6B is a graph of the volume of fluid in the reservoir and the temperature of the fluid as a function of time during the intermittent delivery of relatively small doses, and FIG. 6C to FIG. 6D is a graph of the volume of fluid in the reservoir and the temperature of the fluid as a function of time during intermittent delivery of relatively large doses.

[0052] FIG. 7A to FIG. 7B is a graph of the fluid volume and fluid temperature in the reservoir having the minimum volume as a function of time during intermittent dosing, and FIG. 7C to FIG. 7D Graphs showing the change in fluid temperature caused by a step change in dosage temperature of -1°C and +1°C respectively.

[0053] Fig. 8A is a schematic diagram of a dialysis system according to a second configuration example, and Figure 8B Shows Fig. 8A The dialysis system in the invention implements hemodialysis through CRRT. DETAILED DESCRIPTION

[0054] Embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all, embodiments of the invention are shown. Indeed, the subject matter of the present disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that the present disclosure may satisfy applicable legal requirements. Like numbers refer to like elements throughout.

[0055] Moreover, it should be understood that any advantages, features, functions, devices and / or operational aspects of any embodiment of the present invention described and / or contemplated herein may be included in any other embodiment of the present invention described and / or contemplated herein, and / or vice versa, where possible. In addition, unless otherwise expressly stated, any term expressed in the singular herein is also intended to include the plural form, where possible, and / or vice versa. As used herein, "at least one" should mean "one or more", and these phrases are intended to be interchangeable. Therefore, the terms "a" and / or "an" should 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 requires otherwise due to the language of expression or necessary implication, the word "include" or variations such as "comprises" or "comprising" are used in an inclusive sense, that is, specifying the presence of the described features, but not excluding the presence or addition of other features in various embodiments.

[0056] In addition, it should be understood that although the terms first, second, etc. can be used to describe various elements in this article, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, the first element can be called the second element, and similarly, the second element can be called the first element without departing from the scope of this disclosure. As used herein, the terms "multiple", "plural" and "plurality" are intended to indicate that two or more elements are provided. The term "and / or" includes any and all combinations of one or more associated listed elements.

[0057] For brevity and / or clarity, well-known functions or structures may not be described in detail. Unless otherwise defined, 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 the present disclosure belongs.

[0058] The present disclosure relates to technology for controlling the temperature of medical fluids used in renal replacement therapy (RRT). As used herein, RRT refers to any treatment that replaces or supplements the normal blood filtering function of the kidneys in a patient. RRT can involve removing water from the patient's blood, and exchanging solutes with the blood. RRT is also referred to herein as "dialysis therapy" or "dialysis treatment". The technology for temperature control will be illustrated below with reference to hemodialysis (HD), although it can be applied to any mode of extracorporeal blood therapy or peritoneal dialysis (PD).

[0059] A medical fluid may be any fluid that is consumed as part of RRT and is also referred to as a "treatment fluid (abbreviated TF)". In the context of extracorporeal blood therapy, the medical fluid may be a dialysis fluid that interfaces with the blood in a filtration unit commonly referred to as a "dialyser". Alternatively or additionally, the medical fluid may be a so-called replacement fluid or substitution fluid that is infused into the blood upstream or downstream of the dialyzer, for example as part of hemofiltration (HF) or hemodiafiltration (HDF), as is known in the art. In the context of PD, the medical fluid may be a dialysis fluid that is infused into the patient's peritoneal cavity and interfaces with the patient's blood through the peritoneum lining the peritoneal cavity.

[0060] Now refer to Figure 1A Describe various embodiments, Figure 1AAn example dialysis system 1 is schematically shown, which is fluidically connected to a patient 2 and is operable to perform renal replacement therapy (RRT) on the patient 2. The dialysis system 1 includes a plurality of subsystems: a TF subsystem 3, a supply subsystem 4, a storage subsystem 5, and a processing subsystem 6. The TF subsystem 3 is arranged to provide a processing fluid (TF) for RRT. As known in the art, depending on the implementation, the TF subsystem 3 may include a bag of prefabricated TF or a device for producing TF by mixing purified water with one or more liquid or powder concentrates. The connection path 3' extends between the subsystems 3 and 4 to transfer TF to the supply subsystem 4. The supply subsystem 4 is operable to adjust and supply TF for RRT. In the example shown, the supply subsystem 4 includes a fluid circuit 41, a heating device ("heater") 42, a temperature sensor 43, and a pumping device 44. The fluid circuit 41 is fluidically connected to the path 3'. The heater 42 is configured to heat at least a portion of the TF in the fluid circuit 41 to an operating temperature measured by the sensor 43. The pumping device 44 is configured to supply the heated TF to the storage subsystem 5 via the connection path 4' extending between the subsystems 4 and 5. As will be described in further detail below, the supply subsystem 4 is capable of operating in a "dosing mode" in which the heated TF is intermittently supplied to the storage subsystem 5. In the example shown, the storage subsystem 5 includes a reservoir 50, a weight scale 52, and a measuring device 53. The reservoir 50 is configured to receive the heated TF via the path 4' and to accommodate the intermediate supply of TF during the operation of the dialysis system 1. The weight scale 52 is arranged to measure the weight (mass) of the reservoir 50 during the ongoing RRT, and the device 53 is arranged to measure the temperature of the TF in the reservoir 50. As further explained below, the weight scale 52 and the device 53 are optional. The connection path 5' extends between the subsystems 5 and 6 to transfer TF from the reservoir 50 to the processing subsystem 6. The processing subsystem 6 is configured to obtain TF from the storage subsystem 5 and perform dialysis therapy using TF according to conventional practice. The processing subsystem 6 includes a flow control device 60 configured to obtain TF via path 5' and distribute TF according to the RRT performed. In the example of extracorporeal blood therapy, the flow control device 6 defines an extracorporeal blood circuit that is connected to receive blood from patient 2 via path 6' and return the treated blood to patient 2 via path 6". In the example of PD, the flow control device 6 is configured to supply TF to the peritoneal cavity of patient 2 via path 6' and receive waste TF from the peritoneal cavity via path 6".

[0061] The dialysis system 1 can be implemented by one or more machine units and disposable devices according to conventional practice. The disposable device may include fluid lines, and in the example of extracorporeal blood treatment, may include a blood filtration unit ("dialyzer"). The disposable device can be mechanically connected to one or more machine units to form the dialysis system 1. For example, (one or more) machine units can expose mechanical interfaces of pumps, clamps, sensors, etc.

[0062] like Figure 1A As shown, the control device 7 is configured to control the operation of the dialysis system 1. The control device 7 may be a controller in a machine unit of the dialysis system 1 or a separate controller. The control device 7 does not have to be a single device but may be distributed among multiple controllers in the system 1. The control device 7 is configured to receive measurement signals (denoted as Si) and output control signals (denoted as Cj). Although Figure 1A , but part of the measurement signals and control signals are used to control the processing subsystem 6 to perform RRT on the patient 2. In addition, the control device 7 is configured to control the supply subsystem 4 by providing a control signal C1 to the heater 42 based on a measurement signal ("temperature signal") S1 from the temperature sensor 43 and providing a control signal C2 for the pumping device 44. As shown in the figure, the control device 7 can also receive a measurement signal ("weight signal") S2 from the weight scale 52 and a measurement signal ("temperature signal") S3 from the measuring device 53. In addition, the control device 7 can receive a measurement signal S4 from a temperature sensor 80, which is arranged to measure the ambient temperature ("room temperature") at the location of the dialysis system 1.

[0063] The control device 7 may be configured to generate the control signal Cj according to a control program comprising computer instructions. The control program is further configured to operate based on the measurement signal Si. The control device 7 comprises a processing circuit 71 and a computer memory 72. The control program is stored in the memory 72 and executed by the processing circuit 71. For example, the processing circuit 71 may include one or more of the following: a CPU ("central processing unit"), a DSP ("digital signal processor"), a GPU ("graphics processing unit"), a microprocessor, a microcontroller, an ASIC ("application-specific integrated circuit"), a combination of discrete analog and / or digital components, or some other programmable logic device (e.g., an FPGA ("field programmable gate array"). The control program may be provided to the control device 7 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 a propagated signal. In the example shown, the control device 7 includes a signal interface 73a for providing a control signal Cj and receiving a measurement signal Si. The control device 7 also includes a signal interface 73b for connecting to a user interface (UI) device 74, which enables user interaction, such as inputting control settings and outputting feedback data. For example, the UI device 74 may include one or more of a keyboard, a keypad, a computer mouse, a control button, a printer, a microphone, a display device, an indicator light, an alarm device, a speaker, a touch screen, a camera, a voice control system, a gesture control system, etc.

[0064] Figure 1B is a schematic diagram of a dialysis system 1 for extracorporeal blood treatment by hemodialysis (HD), the dialysis system 1 being in a configuration typically used to treat acute kidney injury (AKI), such as by CRRT. As described below, the system 1 comprises Figure 1A The subsystem in Figure 1A As in the embodiment, the TF subsystem 3 is fluidly connected to the supply subsystem 4 via the path 3', and the supply subsystem 4 is fluidly connected to the reservoir 50 via the path 4'. The reservoir 50 is Figure 1A Part of the storage subsystem 5. The reservoir 50 is arranged on the scale 52. The reservoir can be placed to be placed on the scale 52, rather than being suspended on the scale 52 as shown. The reservoir 50 can be a rigid or flexible container of any material (e.g., plastic). The reservoir 50 is arranged to hold an intermediate supply of treatment fluid TF. In the example shown, the sensor 53 is arranged to measure the temperature of the TF in the reservoir 50. The sensor 53 can be of any type and can be attached to the outside of the reservoir 50 (as shown), arranged inside the reservoir 50, or spaced apart from the reservoir 50. The sensor 53 can be arranged to measure the average temperature of the TF, for example by measuring the temperature at multiple locations. In some embodiments, the sensor 53 is an infrared thermometer, also known as a non-contact thermometer.

[0065] Figure 1B The remaining components of System 1 are Figure 1A Therefore, in Figure 1B In the example of , the processing subsystem 6 is connected to the reservoir 50 via a path 5' fluid. A fluid pump P1 is arranged in the path 5' to pump TF from the reservoir 50 through the dialyzer 10. The dialyzer 10 is a conventional blood filter in which a semipermeable membrane 10' is arranged to define a first chamber for TF and a second chamber for blood. One end of the first chamber is connected to receive TF via the path 5'. TF flows through the first chamber and leaves the dialyzer 10 at the opposite end. The TF leaving the dialyzer 10 is "waste" TF. In order to distinguish between fresh TF and waste TF, waste TF is represented as "effluent" in this article and is designated by EF. The effluent path 11 extends from the first chamber of the dialyzer 10 to the effluent (EF) reservoir 12. The fluid pump P2 is arranged in the path 11 to pump EF into the reservoir 12. The reservoir 12 can be configured corresponding to the reservoir 50 and arranged on the scale 13. The discharge path 14 extends from the reservoir 12 to the discharge portion 15. A fluid pump P3 is arranged in path 14 to pump EF from reservoir 12 to drain 15. The second chamber of the dialyzer 10 is arranged to receive blood from an extraction path 6', which is connected to patient 2 via connector 6a. The second chamber of the dialyzer 10 is also fluidically connected to a return path 6", which extends to a connector 6b connected to patient 2. Connectors 6a, 6b are access devices (catheters, needles, etc.) that are fluidically connected to the circulatory system of patient 2. Fluid pump P4 is arranged to pump blood from patient 2 via extraction path 6' through the second chamber of the dialyzer 10 and back to patient 2 via return path 6". While passing through the second chamber, the blood connects with TF through membrane 10' and is thereby processed by hemodialysis. The principles of hemodialysis are well known to those skilled in the art and will not be further explained herein. It should be understood that Figure 1B The examples in are simplified and may include other conventional components such as clamps, pressure sensors, air detectors, etc.

[0066] To perform HD treatment, the dialysis system 1 is operated to pump TF from the reservoir 50 to the dialyzer 10 by pump P1, EF from the dialyzer is pumped by pump P2, and blood is pumped through the dialyzer 10 by pump P4. During HD treatment, fluid is removed from the blood according to the flow difference generated by pumps P1, P2. The fluid removal process is known in the art as ultrafiltration. In the example shown, and in accordance with conventional practice, the amount of ultrafiltration is accurately monitored based on the weight of the reservoirs 50, 12 given by scales 52, 13. However, a flow meter or volumetric pumping can be used instead to monitor the amount of treatment fluid supplied to the dialyzer 10 and the amount of effluent drawn from the dialyzer 10, respectively. During treatment, TF is supplied by operating the supply subsystem 4 to intermittently replenish the TF reservoir 50. In addition, the EF reservoir 12 can be intermittently discharged in any suitable manner. In the example shown, pump P4 is operated to pump EF from the EF reservoir 12 to the discharge 15. In another example, when the EF reservoir 12 is full, it is removed and replaced with an empty EF reservoir. In other examples, the dialysis system 1 includes two EF reservoirs and is operated to direct EF flow into one EF container while draining the other EF container.

[0067] In the following description, it is assumed that the supply subsystem 5 lacks a device for heating the TF in the reservoir 50. Therefore, the reservoir 50 is "unheated". When TF is contained in the non-heated reservoir 50, it will lose heat to the surrounding environment and gradually cool down. It may be noted that it may be desirable to avoid frequent replenishment of the TF reservoir 50 because the monitoring of ultrafiltration becomes less accurate during such replenishment. Therefore, the residence time in the reservoir 50 may be quite long. For example, in CRRT, 5 liters of TF may be consumed in about 2 hours. Experiments have shown that a plastic bag initially filled with TF at 38°C and placed in a 20°C room for 2 hours may contain TF at 28°C after 2 hours. In this case, the patient will experience significant cooling through the TF. This cooling is harmful to the health and comfort of the patient. For example, it has been reported that hypothermia in dialysis patients can cause shivering, loss of fine motor coordination, drowsiness, and mild confusion. Other reported consequences of hypothermia include immunosuppression (increased risk of infection), cold diuresis, depletion of blood volume, electrolyte disturbances, insulin resistance, impaired drug clearance, mild coagulopathy, cardiac problems, and even cardiac arrest.

[0068] A non-heated reservoir 50 may be used in the dialysis system 1 for a number of reasons. First, if an existing machine unit without heating capabilities is used as part of the dialysis system 1, the reservoir 50 may have to be unheated. Even if a new dialysis system 1 is developed, it may be desirable for the reservoir 50 to be unheated. For example, it may be difficult to achieve uniform heating of the TF in the reservoir 50, and special care may be required to avoid causing localized high temperatures that may negatively affect the TF. For example, TF that includes bicarbonate is known to release increasing amounts of carbon dioxide as the temperature increases. In addition, for TF containing bicarbonate, precipitation may be exacerbated as the temperature increases.

[0069] The temperature of the TF in the reservoir 50 is conducive to microbial growth. If the reservoir 50 is permanently installed in the dialysis system 1, it needs to be disinfected, for example, between treatments. If the volume of the reservoir 50 is large, it may be difficult to determine whether it is thoroughly disinfected, and if the reservoir 50 is designed for relatively small inflow and outflow flows, disinfection may take a considerable time. Therefore, it may be desirable that the reservoir 50 is part of a disposable device so that the reservoir 50 can be replaced when necessary, such as between treatments or at predetermined intervals. Heating such a disposable reservoir requires providing a customized heating device in the dialysis system 1 to achieve thorough and gentle heating of the TF in the disposable reservoir 50.

[0070] exist Figure 1B In the example of , the reservoir 50 is part of a disposable device that is removably connected to the supply subsystem 4. Figure 1B In the embodiment, the disposable device includes a fluid path 4', a reservoir 50, a fluid path 5', an effluent path 11, a reservoir 12, a discharge path 14, a dialyzer 10, an extraction path 6' and a return path 6". The fluid paths 4', 5', 6', 6", 11, 14 can be defined by fluid channels and / or fluid lines (as shown) of a single structure such as a cassette. The fluid path includes connectors 19a, 19b, 19c, 19d, 19e for detachably engaging with corresponding connectors to establish a fluid connection. As is known in the art, pumps P1, P2, P3, P4 can be peristaltic pumps that include a mechanical interface for engaging a dedicated section of the fluid line. Alternatively, one or more of the pumps P1-P4 can be integrated into the disposable device, for example in the form of a disposable diaphragm pump.

[0071] Figure 2A is a flow chart of an example method 200 that addresses the problem of maintaining and / or regulating the temperature of a fluid in a non-heated reservoir. Figure 1A to Figure 1BThe method 200 is described with reference to the dialysis system 1 in FIG. 1 and can be executed by the control device 7. The method 200 operates the supply subsystem 4 to perform a series of fluid supply cycles, wherein each fluid supply cycle involves supplying at least one fluid dose to the non-heated reservoir 50. The respective doses are supplied within a dose period (BP). As used herein, a "dose" refers to an amount of fluid supplied to the reservoir 50 within a limited period of time. Thus, a dose is an amount of fluid supplied intermittently. Figure 1A to Figure 1B In the dialysis system 1 of FIG. 5 , the doses contain heated TF. Consecutive BPs are separated by idle periods (IPs) during which the supply subsystem 4 does not supply any fluid to the reservoir 50. The number of doses within a fluid supply cycle and the specific time of each BP and IP are predefined, so the control device 7 knows these. A fluid supply cycle can include any number of BPs and IPs, and the corresponding BP can be located at any position (specific time) within the fluid supply cycle.

[0072] Each fluid supply cycle is assigned a target temperature to be reached by the fluid in the reservoir 50. By operating the supply subsystem 4 through the method 200, the energy content of the corresponding dose supplied during the fluid supply cycle is adjusted to achieve the target temperature of the fluid supply cycle. In some embodiments, by operating the heater 42 ( Figure 1A ) at least partially adjusts the energy content.

[0073] Figure 2B to Figure 2C Two example sequences of fluid supply cycles are shown, which are timing diagrams of doses B separated in time by idle periods IP. Each fluid supply cycle FSC is assigned a target temperature TT to be achieved in the FSC. Figure 2B In , each FSC involves a single dose B and is preceded by an idle period IP. Figure 2C Each FSC involves two doses B, each dose B is followed by a corresponding rest period IP.

[0074] In the following non-limiting example, the method 200 will be described and explained for a fluid supply cycle including a single IP and a single BP, wherein the IP is located before the BP, such as Figure 2A It should be understood that the following description is generally applicable to other definitions of a fluid supply cycle in terms of the number of doses within the fluid supply cycle and the specific timing of the respective doses.

[0075] In step 201, a target temperature is obtained. The target temperature (TT) can be given by any measure representing the temperature of the fluid in the reservoir 50 during the fluid supply cycle. In some embodiments, TT is the temperature at a selected time point ("target time point") within the fluid supply cycle, for example, at the beginning or end of IP or BP. In some embodiments, TT is the time average of the fluid temperature in the reservoir 50 during the fluid supply cycle or a portion thereof. In the example below, TT is the fluid temperature at the end of BP. The user can enter the target temperature through the UI device 74, or the target temperature can be retrieved from the memory 72 as a predefined setting. It is also conceivable that the user is allowed to enter the desired temperature downstream of the reservoir 50, such as the temperature of the TF entering the dialyzer 10 or the temperature of the blood downstream of the dialyzer 10. In this variation, the control device 7 is configured to recalculate the desired temperature as the target temperature of the fluid in the reservoir 50 by taking into account the energy loss downstream of the reservoir 50.

[0076] In step 202, the processing subsystem 6 is operated to perform dialysis therapy during a treatment session while obtaining TF from the reservoir 50, e.g., as described above. In some embodiments, step 202 is performed continuously during all subsequent steps 203-205. In a variation, the dialysis therapy is suspended during the BP (step 205, below), meaning that TF is not removed from the reservoir 50 during the BP.

[0077] although Figure 2A Not shown in FIG. 4 , method 400 includes the following steps: before starting the treatment period in step 202, operating supply subsystem 4 to fill a predetermined amount of fluid at a predetermined temperature into reservoir 50. The predetermined temperature may be set according to a target temperature.

[0078] The sequence of steps 203-205 is repeatedly performed to produce the above series of fluid supply cycles. In step 203, the supply subsystem 4 is operated to not supply TF to the reservoir 50 via the fluid path 4'. Therefore, step 203 produces an idle period IP. In step 204, the required energy content of the dose to be supplied in the subsequent dose period is determined. The required energy content is determined to achieve the target temperature in the fluid supply cycle. In step 205, the supply subsystem 4 is operated to prepare and supply a TF dose with the required energy content. Therefore, step 205 produces a dose period BP.

[0079] The method 200 provides a technical advantage of achieving a target temperature of the fluid in the reservoir 50 without installing a dedicated heating device in or around the reservoir 50. In addition, using the fluid supply cycle to heat the fluid in the reservoir 50 itself involves gentle heating. If the TF is known to degrade at a temperature above a temperature limit, the temperature of the dose will be maintained below the temperature limit, so the fluid in the reservoir 50 will not be subjected to a temperature above the temperature limit when the dose is supplied.

[0080] It should be noted that step 204 need not be performed every time steps 203-205 are repeated. In some embodiments, step 204 is performed during a subset of fluid supply cycles. In some embodiments, step 204 is performed before a series of fluid supply cycles, i.e., before starting a repeating sequence of steps 203, 205.

[0081] In some embodiments, Figure 2A As shown by the dashed line in , step 204 includes step 204A of configuring the dose to have a desired energy content by determining a specified size and a specified temperature of the dose. The specified size can be given as a volume or a mass. In the following, the specified size of the dose is represented as a dose mass (mb). The specified temperature of the dose is represented as a dose temperature (Tb).

[0082] In step 205, the control device 7 operates the supply subsystem 4 using control signals C1, C2 to perform a dosing period. The control device 7 generates a control signal C1 based on the temperature signal S1 to operate the heater 42 to heat the fluid portion of the treatment fluid to Tb, and generates a control signal C2 to operate the pumping device 44 to supply at least part of the heated fluid portion during the dosing period.

[0083] In some embodiments, step 204A includes determining the mass of the dose based on a weight signal S2 from the scale 52 , which represents the weight of the reservoir 50 and is therefore indicative of the instantaneous mass of fluid in the reservoir 50 .

[0084] In some embodiments, step 204A includes determining the dose temperature based on a temperature signal S3 from a sensor 53, the temperature signal S3 representing the temperature of the fluid in the reservoir 50. However, in some embodiments, the sensor 53 is omitted, for example to reduce complexity and / or cost. In such embodiments, the temperature of the fluid in the reservoir 50 can be estimated by using a computational model of the energy losses of the reservoir 50, as will be further described below.

[0085] Figure 3A is an example graph of fluid mass (mr) in reservoir 50 versus time (t). Specifically, Figure 3A2 shows mr during a BP-IP-BP sequence performed by method 200. Here, a fluid supply cycle (FSC) is defined by an IP followed by a BP. Time ts indicates the start of a BP and time te indicates the end of a BP. Figure 3A In the example of , the processing subsystem 6 consumes TF at a constant flow rate during IP and BP. Therefore, as shown by line 301, mr decreases linearly during IP from m2 at the beginning of IP. At point 302 corresponding to the beginning of BP, mr is m1. As indicated by line 304, a dose is supplied to the reservoir 50 during BP, resulting in an increase in fluid mass. In the example shown, method 200 is performed to restore the fluid mass during each fluid supply cycle. Therefore, at the end of BP (point 305), mr is m2. Since fluid is also removed from the reservoir during BP, as indicated by dotted line 303, the dose mass mb is determined (step 204A) to match the total fluid removal during the fluid supply cycle FSC.

[0086] Figure 3B is a corresponding example graph of the fluid temperature (Tr) in the reservoir 50 during the sequence BP-IP-BP. Figure 3B In the example of , it is assumed that the target temperature TT defines the fluid temperature at the end of the BP. As indicated by line 311, the temperature decreases during the IP. The temperature decrease is caused by the dissipation of heat energy to the surrounding environment of the reservoir 5 and the removal of the fluid by the processing subsystem 6. At point 312 corresponding to the start of the BP, Tr is T1. As indicated by line 314, Tr increases as the dose is supplied to the reservoir 50 during the BP. At the end of the BP (point 315), Tr has reached the target temperature TT.

[0087] Back to Figure 2A In step 204, the energy content required for the corresponding dose can be determined based on an estimate or simulation of the energy loss of the fluid in the reservoir 50 during one or more fluid supply cycles. If step 204 is performed before a series of fluid supply cycles, the estimation continues to multiple subsequent fluid supply cycles. If step 204 is performed during an ongoing fluid supply cycle, the estimation continues at least to the ongoing fluid supply cycle. FIG. 4A to FIG. 4E An example of estimation is given.

[0088] In step 205, the control device 7 can prepare the fluid portion for producing the dose according to the required energy content given in step 204. Figure 3B In the example of FIG. 3 , point 316 represents the point in time at which the control device 7 starts preparing the fluid portion. It is recognized that, for example, if the dose temperature is different from the dose temperature in the previous fluid supply cycle and / or if the heater 42 ( Figure 1A) is deactivated between dosing periods to save energy, a preparation time Δt1 may be required to heat the fluid portion to the dosing temperature (Tb). The preparation time Δt1 may be dynamically determined or predefined by the control device 7, for example based on the temperature signal S1. It is recognized that step 204 may also need to be completed at point 316 in order to know the dosing temperature.

[0089] exist Figure 2A In the example of , the target temperature is set in step 201 before the dialysis therapy begins and remains unchanged throughout the dialysis therapy performed in step 202. It is also contemplated that the target temperature is defined to vary according to a predefined time profile during the dialysis therapy. For example, the user may input the time profile through the UI device 74 before the dialysis therapy begins. Thus, the target temperature may vary between fluid supply cycles. In another variation, the user may be allowed to adjust the target temperature during an ongoing dialysis therapy, which may also result in a target temperature variation between fluid supply cycles. Figure 3C Corresponds to Figure 3B , and shows a scenario where the target temperature increases from TT' of the previous cycle to TT of the current cycle.

[0090] Back to Figure 2A In steps 204-205 of the present invention, the desired energy content of the dose may be achieved by adjusting the dose mass (mb), the dose temperature (Tb), or both. Adjusting both mb and Tb offers the potential advantage of increased flexibility in achieving the desired energy content. However, the flexibility of adjusting mb may be limited by other considerations. For example, mb may be set to achieve a predefined target value of the mass of fluid in the reservoir (mr) after BP. Figure 3A In the example of , the target mass for each fluid supply cycle is the same, so the reservoir 50 is refilled to the same level. In general, this means that the energy content required for the dose is determined in part based on the amount of fluid removed from the non-heated reservoir 50 during the fluid supply cycle ("total fluid removal"). In some embodiments, the total fluid removal is given by the control settings of the processing subsystem 6. Alternatively or additionally, the control device 7 can estimate the total fluid removal based on a measurement, such as a weight signal S2 from the scale 52.

[0091] It is therefore recognized that the dose mass (mb) can be given by the total fluid removal during the fluid supply cycle, and the dose temperature (Tb) can be determined such that the combination of the dose mass and the dose temperature corresponds to the required energy content of the dose. 4A to 4F As shown, the calculation in step 204 can be simplified when the dose quality is known and only the dose temperature is adjusted to meet the required energy content.

[0092] In some embodiments, step 204 includes estimating the total energy loss of the fluid in the reservoir 50 during the corresponding fluid supply cycle and determining the energy content required for the dose based on the total energy loss. A computational model may be used to estimate the total energy loss. Figure 4A Various variables that may be included in such a computational model are shown. Figure 4A The fluid circuit 41, the connection path 4', the reservoir 50 and the connection path 5' of the supply subsystem 4 are shown. Variables include the ambient temperature Ta, the fluid temperature Tr in the reservoir, the dose temperature Tb, the dose mass mb and the fluid mass mr in the reservoir. Variables also include the energy content Er of the fluid in the reservoir, the energy loss Eh of the fluid dissipation in the reservoir, the energy loss Ec caused by the processing subsystem 6 removing ("consuming") the fluid from the reservoir via the path 5', and the energy loss E' of the fluid dissipation in the path 4'. The total energy loss is given by the sum of Eh, Ec and E'. It should be noted that if E' is considered insignificant, for example, if the path 4' is short, E' can be omitted. As used herein, "dissipation" refers to energy lost due to the transfer of heat to the surrounding environment, and depending on the implementation, may include heat conduction, heat convection or heat radiation, or any combination thereof.

[0093] The computational models are based on sets of equations that can be derived analytically and / or empirically. Appendix A contains the analytically derived Figure 4A An example of an equation describing the energy loss of a fluid with the variables shown in .

[0094] FIG. 4B to FIG. 4E An example of how the control device 7 may use the calculation model to determine the dose mass (mb) and the dose temperature (Tb) according to step 204A is shown. Figure 4B 4 is a block diagram of an example calculation model 400 in the control device 7. The calculation model 400 may be implemented by software executed by the processing circuit 71 and / or a dedicated portion of the processing circuit 71. The calculation model 400 is configured to input and operate on the target temperature TT, the characteristic data PD and the reference measurement data RMD to determine and output the dose mass mb and the dose temperature Tb of the corresponding fluid supply cycle. The characteristic data PD defines the operation of the dialysis system 1, such as the reservoir fluid removal rate, the specific time of the dose period within the fluid supply cycle, the fluid supply rate of the dose within the dose period, etc. The reference measurement data RMD includes Figure 4A The measured values ​​of one or more of the variables in at one or more reference time points before or during the fluid supply cycle, for example, Tr, mr, Ta, etc.

[0095] Figure 4C Shows Figure 4B4. The calculation model 400 includes a first calculation block 410 and a second calculation block 411 for operating on PD and RMD. The first block 411 is configured to calculate the energy loss (denoted as E lossIP The second block 411 is configured to calculate the energy loss (denoted as E) during the dose period. lossBP ). Both blocks 410, 411 are configured to estimate energy losses due to dissipation and due to fluid removal. Examples of functions used by blocks 410, 411 are given in Appendix A. The functions in Appendix A are determined analytically and omit Figure 4A The energy loss E' in the calculation model 400 is shown in FIG. 4. It is also simple to include E'. As described in Appendix A, the corresponding function can be determined at least in part empirically instead. The calculation model 400 also includes a third block 415, which is configured to calculate the energy loss E' based on the target temperature, E lossIP and E lossBP To determine the energy content required for the dose. Based on the required energy content, block 415 determines and outputs mb and Tb. Block 415 may also take into account any constraints imposed on mb and / or Tb, such as a maximum limit on Tb, or that mb should match the total fluid removal during the fluid supply cycle.

[0096] In some embodiments, the computational model 400 is configured to perform an iterative calculation to determine mb and Tb. The iterative calculation is performed by Figure 4C 415 to 411 in FIG. 4. Iterative calculations may be performed to take into account the fact that the instantaneous temperature (Tr) of the fluid in the reservoir during a dosing period will depend not only on the instantaneous energy added by the dose, but also on the instantaneous energy loss, which in turn depends on Tr. It may be noted that if the second function used by block 411 is at least partially determined empirically, for example based on Tr at the beginning and end of a dosing period (see FIG. 3B to FIG. 3C If the points 312, 315 in FIG. 3 approximate the energy loss during the dose period, iterative calculations can be avoided.

[0097] Figure 4D According to Appendix A Figure 4C Functional diagram of an example implementation of blocks 410-411 in FIG. In the example shown, the characteristic data (PD) includes time data ([t] FSC ) 421, which defines a dosing period at a specific time during a fluid supply cycle. FIG. 3A to FIG. 3CIn an example of , the time data 421 can indicate a time point ts, te associated with the start of a fluid supply cycle. The PD also includes a dose time curve (qb(t)) 422, which defines the dose flow rate as a function of time within the dose period. The total dose flow rate within the dose period is equal to mb. In an example, the dose time curve 422 can be given by a constant value within the dose period. The PD also includes a removal time curve (qc(t)) 423, which defines the reservoir fluid removal rate as a function of time during the fluid supply cycle. As described above, the removal time curve 423 can be given by a setting for the processing subsystem 6 and / or estimated based on the weight signal S2.

[0098] exist Figure 4D In the example of FIG. 4 , the reference measurement data (RMD) includes the ambient temperature (Ta(t)) 424, which is obtained by the sensor 80 ( Figure 1A ) is measured at one or more time points before or during the dialysis treatment. The RMD also includes a measurement 425 of the fluid temperature in the reservoir at a first reference time point Tr(t0). In Appendix A, Tr(t0) is denoted as T0. If the reservoir 50 is connected to a temperature sensor (see Figure 1A 53 in FIG. 5 ), Tr(t0) can be obtained from the temperature sensor at any time point before or during the dialysis treatment. Otherwise, Tr(t0) can be inferred from the temperature of the fluid supplied to the reservoir 50 by the supply subsystem 4 before the dialysis treatment is started. In another alternative, the supply subsystem 4 can be operated to draw fluid from the reservoir 50 and measure the temperature of the fluid, for example, by the sensor 43. In other alternatives, Tr(t0) can be obtained from a sensor located downstream of the reservoir 50 (for example, at Figure 1B Tr(t0) is inferred from a temperature value measured in path 5' or in path 6" downstream of pump P1. A person skilled in the art recognizes that such a temperature value can be converted to the temperature of the fluid in reservoir 50 by estimating and taking into account energy losses between the reservoir and the sensor.

[0099] exist Figure 4D In the embodiment, the RDM also includes a measurement 426 of the mass of the fluid in the reservoir at a second reference time point, namely mr(t0). The first reference time point and the second reference time point may be different or the same. It is also conceivable that the RDM includes Tr and / or mr measured at more than one reference time point.

[0100] To simplify notation and correspond to Appendix A, qb(t), qc(t), and Ta(t) are assumed to be constants (time-invariant). Figure 4DThe implementation in includes multiple time-dependent functions 427-431, which are evaluated based on PD and RMD. Function 427 is operable to estimate the instantaneous fluid mass mr(t) in the reservoir at any time point t. Referring to Appendix A, function 427 can be executed according to equation 4 during the idle period and according to equation 8 during the dosage period. Function 428 is operable to estimate the heat dissipation area A(t) of the fluid in the reservoir at any time point. Referring to Appendix A, function 428 can be executed according to equation 5 during the idle period and according to equation 9 during the dosage period. It can be seen that function 428 operates on the output of function 427. However, as described in Appendix A, other equations can be developed for function 428. In another alternative, the heat dissipation area is set to a constant (time-invariant) value. Function 429 is operable to estimate the fluid temperature Tr(t) in the reservoir at any time point. Referring to Appendix A, function 429 can be executed according to equation 14 or a corresponding equation. It can be seen that function 429 operates on the output of function 427 (instantaneous fluid mass) and the output of function 428 (instantaneous heat sink area). Function 430 can be operated to estimate E lossIP Referring to Appendix A, function 430 may be executed according to equation 7. It can be seen that function 430 operates on the output of function 428 (instantaneous heat dissipation area) and the output of function 429 (instantaneous temperature). Function 431 may be operated to estimate E lossBP Referring to Appendix A, function 431 can be executed according to equation 15. It can be seen that function 431 operates on the output of function 427 (instantaneous fluid mass), the output of function 428 (instantaneous heat dissipation area), and the output of function 429 (instantaneous temperature). The outputs of functions 430 and 431 correspond to Figure 4C Output of middle frames 410 and 411.

[0101] As can be seen from Appendix A, one or more of the functions in the calculation model 400 may depend on Tb and / or mb. Therefore, the calculation model may involve iterative calculations to derive Tb and / or mb based on the target temperature TT. Iterative calculations can be implemented in many different ways. Figure 4E A non-limiting example is shown in . Figure 4E The computational model in is based on rearranging the equation in Appendix A into the following subfunctions:

[0102] m r (t) = f1(m r (t0),q c ,q b ,ts,t)

[0103] T r,IP (t) = f2(m r (t),T0,t)

[0104] Tr,BP (t) = f3(T r,IP (ts),q c ,q b ,m r (t0),Tb,t)

[0105] Among them, T r,IP (t) and T r,BP (t) denotes the fluid temperature in the reservoir during IP and BP, respectively. In addition, the computational model includes a sub-function for calculating the current value of the target temperature:

[0106] TTa=f4(T r,IP (t),T r,BP (t))

[0107] Realize that f4 depends on the definition of the target temperature and not necessarily on T r,IP (t) and T r,BP (t) Both. For example, if the target temperature is the fluid temperature at the end of the dosing period, only f4 depends on T r,BP (t).

[0108] For simplicity, the dependence on PD and RMD is only schematically shown in Figure 4E and may be related to Figure 4D Similarly, function 428 can be used for Figure 4D As described. Function 427 includes f1 for calculating mr(t), and function 429 includes f2 and f3 for calculating Tr(t) during IP and BP, respectively. Since f3 depends on Tb, the calculation model includes box 436, which is configured to provide the value of Tb to function 429 for calculating Tr(t). The calculation model also includes box 435, which operates f4 to calculate TTa and provides an error signal indicating the difference between TTa and TT to box 436. Box 436 includes a conventional optimization algorithm for determining a new value of Tb based on the error signal. Therefore, box 436 first provides an initial value of Tb, and then repeatedly optimizes Tb based on the error signal to minimize the difference between TTa and TT. When the difference meets the convergence criteria, box 436 outputs Tb. Figure 4E The examples in assume that mb is known, but can be modified to determine mb.

[0109] FIG. 4A to FIG. 4Eis a specific example of a more general embodiment of the calculation model. In one embodiment, the calculation model 400 is configured to calculate the instantaneous fluid temperature in the reservoir 50 during the corresponding fluid supply cycle (see Tr(t)), and operate on the instantaneous fluid temperature to determine the energy content of the dose ("required energy content") to achieve the target temperature (TT). The calculation of the instantaneous fluid temperature provides an effective method for determining the required energy content and helps to evaluate the achievement of TT. In one embodiment, the control device 7 is configured to obtain a measured value of the instantaneous fluid temperature in the reservoir 50 at a reference time point (see mr(t0)), and the calculation model 400 is configured to calculate the instantaneous fluid temperature in the reservoir 50 based on the measured value. Using the measured value provides a simple way to estimate the instantaneous fluid temperature, wherein the measured value forms an anchor value or starting value for calculating the instantaneous fluid temperature at other time points. In one embodiment, the calculation model 400 is configured to calculate the instantaneous heat dissipation area of ​​the reservoir 50 (see A(t)) and / or the instantaneous fluid volume in the reservoir 50 (see mr(t)), and estimate the instantaneous fluid temperature as a function of the instantaneous heat dissipation area and / or the instantaneous fluid volume in the reservoir 50. As described above, the instantaneous fluid volume may alternatively be known and / or measured, and the heat dissipation area may alternatively be set to a constant value and / or determined empirically. By calculating A(t), for example, based on mr(t) rather than using a constant value, the accuracy of Tr(t) may be significantly improved. In addition, by calculating mr(t), the calculation of Tr(t) is less dependent on measurement errors and / or predefined settings. In one embodiment, the control device 7 is configured to obtain input data used by the calculation model 400, wherein the input data indicates the duration of the corresponding fluid supply cycle, the specific time of the BP within the corresponding fluid supply cycle (see ts), the duration of the BP (see the difference between ts and te), and the time profile of the removal of fluid from the reservoir 50 during the corresponding fluid supply cycle (see qc(t)). As described above, qc(t) can be given by the operating settings of the processing subsystem 6 or the measured flow rate of the fluid entering the processing subsystem 6. In one embodiment, the calculation model 400 includes a function for estimating the energy loss of the reservoir 50 during the BP (see E lossBP ), which takes into account the temperature change of the fluid in the reservoir 50 caused by the dosage supply. Although such a function may increase the complexity of the calculation model 400, it will also improve the accuracy of the calculation and ultimately improve the control of the temperature of the fluid in the reservoir 50.

[0110] refer to Figure 3B, where the target temperature (TT) is the same for a plurality of consecutive fluid supply cycles, the control device 7 can be operated in a "steady state mode" in which the energy content required for the dose of the corresponding fluid supply cycle is set equal to the total energy loss during the fluid supply cycle. This can significantly simplify the calculation of mb and / or Tb. For example, if mb is known, and as long as the ambient temperature does not change, then Tb will be the same for each dose in the sequence of fluid supply cycles.

[0111] Figure 4F It can be used as Figure 2A A flowchart of a process 440 for executing a portion of steps 204-205 of method 200 is provided. FIG. 3A to FIG. 3C Describe procedure 440. In step 441, the start time and / or end time of the next dosage period BP is obtained. This corresponds to obtaining FIG. 3A to FIG. 3C ts and / or te in. In step 442, the dose mass (mb) is determined to refill the reservoir 50. Assuming the fluid removal rate (qc(t)) is known, the total fluid removal amount of the fluid supply cycle is given by the fluid removal rate and the duration of the fluid supply cycle. If the dose supply rate is fixed, the procedure 440 may include a step 443 of determining the duration of the dose period required to supply mb. Based on the required duration, the start time and / or end time of the BP may be determined in step 443. It is recognized that step 443 is optional and the duration of the BP may be fixed and given by the start time and end time obtained in step 441. In step 444, the dose temperature (Tb) is determined, for example, as described in reference FIG. 4A to FIG. 4E Steps 441-444 are completed at least Δt1 before ts. In step 445, the supply subsystem 4 is operated to heat the fluid portion to Tb. In step 446, at time ts, BP is started by starting the dosage supply. In step 447, at time te, BP is terminated by stopping the dosage supply.

[0112] As indicated by the dashed line, routine 440 may include an optional step 448 of obtaining a measurement indicating the instantaneous fluid temperature in the reservoir at a selected point in time. Step 448 may be performed at any time during a fluid supply cycle, and need not be performed for each fluid supply cycle. The measurement may correspond to measurement 425 ( Figure 4D) is obtained. In step 448, the measured value is evaluated relative to the calculated value of Tr at the selected time point. If a significant deviation is detected in step 448, step 449 is performed to adjust the calculated value of Tr and / or the calculation model 400 based on the measured value. For example, the calculated value can be adjusted by applying the measured value 426 as a reference value for the subsequent calculation of Tr(t), similar to the measured value 425 (Tr(t0)). The calculation model 400 can be adjusted by modifying one or more parameters of the calculation model 400 so that the calculated value matches the measured value at the selected time point.

[0113] In some embodiments, the control device 7 is configured to, when the reservoir 50 has a predefined weight (e.g., as determined by the scale 52 ( Figure 1A to Figure 1B ) measured) causes the supply subsystem 4 to supply the dose. This means that the start of BP is dynamic and triggered by the weight signal S2. Return to Figure 4F In step 441, the start time ts of BP can be estimated based on mr(t), regardless of whether mr(t) is based on FIG. 4D to FIG. 4E The calculation is still measured by the scale 52. Figure 3A In the example of , assuming that BP is triggered when mr is m1, step 441 can determine ts by extrapolating curve 301 from any time point during IP.

[0114] In some embodiments, the control device 7 is configured to perform open loop control on the supply subsystem 4 to achieve a target temperature in the reservoir 50. Such an embodiment may be applied when there is no temperature sensor associated with the reservoir 50. The open loop control enables a simple and robust control of the temperature of the fluid in the reservoir 50. Figure 5A is a block diagram of an example control module 501, which is configured to generate control signals C1, C2 for the supply subsystem 4 based on the target temperature TT. The control module 501 includes a calculation module 502, which is configured to determine the energy content Eb required for the dose as a basis for generating C1, C2. In the example shown, the calculation module 502 calculates S1, S2 and S4 ( Figure 1A ) is operated to determine Eb. Control signals C1, C2 are provided to the heater 42 and pumping device 44 in the supply subsystem 4 to produce a dose with the required energy content to bring the fluid in the reservoir 50 to TTa, assuming that TTa is substantially equal to TT.

[0115] In some embodiments, the control device 7 is configured to perform closed-loop control on the supply subsystem 4 to achieve a target temperature in the reservoir 50. When the dialysis system 1 includes a temperature sensor (e.g., Figure 1A to Figure 1B This embodiment can be applied when a temperature sensor 53 is provided in the reservoir 50. Closed-loop control enables accurate control of the temperature of the fluid in the reservoir 50. Figure 5Bis a block diagram of an example control module 501', which is configured to generate control signals C1, C2 for the supply subsystem 4 based on the error signal e provided by the difference module 503. The control module 501' includes a calculation module 502, which can be connected with Figure 5A The same as module 502 in Figure 5A Similarly, control signals C1 and C2 are generated by the control module 501' and provided to the heater 42 and the pumping device 44 in the supply subsystem 4 to generate a dose with a desired energy content Eb so that the fluid in the reservoir 50 reaches the actual temperature TTa. The actual temperature TTa is measured by the temperature sensor 53 and provided as a signal S3 to the difference module 503, which is configured to generate an error signal e to represent the difference between TT and TTa. The control module 501' includes any conventional control algorithm for generating control signals C1 and C2 based on the error signal e, such as a P, PI or PID algorithm. In some embodiments, Figure 5B The control device in is operated to modify C1, C2 during the ongoing BP. However, it should be recognized that the response time between the change in TTa measured by sensor 53 and the change in C1, C2 may be long. Therefore, in some embodiments, Figure 5B The control means in is operated to modify C1, C2 before, but not during, the respective dosage period BP.

[0116] The fluid supply cycle is defined by control parameters, which can be set according to the requirements of the processing subsystem and other considerations described below. Two such control parameters are dose mass (mb) and dose period frequency ("BP frequency"), which are interdependent. In some embodiments, as described above, dose mass can be set to match the total fluid removal so that the mass (or volume) of fluid remains relatively constant in the reservoir. Dose mass defines the temperature change in the reservoir. Fig. 6A and Figure 6C Graph of the fluid volume (Vr) in the reservoir as a function of time for dose volumes of 200 ml and 600 ml respectively. Figure 6B and Fig.6DIt is a corresponding chart of the fluid temperature (Tr) in the reservoir when the target temperature (TT) is 38°C. It can be seen that the temperature changes during the fluid supply cycle are approximately 0.6°C and 1.8°C, respectively. If limiting the Tr change is the only goal, a small dose mass should be supplied at a high frequency. However, this approach may increase the cost and complexity of subsystems 3 and 4, and subsystems 3 and 4 must be designed for frequent preparation and supply of dose masses with the correct composition and temperature. For example, if the treatment fluid is produced by mixing water and (one or more) concentrates, the TF subsystem 3 may need to be configured to perform continuous mixing between dose periods and send the treatment fluid to the discharge. This leads to waste of treatment fluid and is costly. In addition, if the measurement of the fluid mass in the reservoir 50 by the scale 52 is interrupted by frequent dose periods, the ultrafiltration accuracy may be affected. Therefore, a balance between temperature fluctuations and BP frequency is sought. It is currently believed that temperature fluctuations of less than about 5°C are acceptable. For temperature fluctuations of less than about 4°C, 3°C, 2°C or 1°C, even better performance is achieved. This allowable temperature fluctuation can be used as a design parameter for the fluid supply cycle to determine the dose mass and thus the BP frequency. In addition, it is currently believed that the lower limit of the time between dosage periods is 5 minutes, preferably 10 or 15 minutes. The upper limit may be 30 minutes, 1 hour or 2 hours. Finally, the upper limit is determined by the fluid removal rate in the reservoir (q in Appendix A). c ) and the size of the reservoir. For example, during extracorporeal blood treatment, the treatment fluid is typically consumed at a rate of 20-100 ml / min, depending on the size of the patient.

[0117] Another control parameter of the fluid supply cycle is the minimum fluid mass (volume) in the reservoir. The minimum fluid mass is reached at the end of the idle period (IP), Fig. 6A and Figure 6Cdenoted as V1 in the figure and can be considered as a buffer volume. The buffer volume enables dialysis therapy to continue even if the TF subsystem 3 or the supply subsystem 4 is temporarily disabled, for example during replacement of an empty treatment fluid or concentrate bag. This would indicate that the buffer volume in the reservoir is large, for example at least about 50%, 60%, 70%, 80% or 90% of its maximum fluid volume. However, a large buffer volume also results in a larger surface area A that loses energy to the environment (see Appendix A), thereby increasing the required dose energy. If the dose mass is set to match the total fluid removal, the increased dose energy corresponds to an increased dose temperature (Tb). In some cases, Tb may need to be as high as 70°C. As described above, this fluid temperature is not suitable for all treatment fluids. In addition, patient safety may be compromised because errors may result in hot fluid being supplied to the treatment subsystem 6. It is currently believed that the buffer volume should be kept small, but large enough to maintain dialysis therapy in the event of a temporary interruption of the fluid supply to the reservoir. Therefore, the buffer volume can be set according to the fluid removal rate in the reservoir during the ongoing therapy.

[0118] Fig. 7A is a graph of the fluid volume (Vr) in the reservoir as a function of time for a buffer volume of 500 ml. Figure 7B is a corresponding graph of the fluid temperature (Tr) in the reservoir for a target temperature of 38° C. Assuming that the treatment fluid is removed from the reservoir at a rate of 35 ml / min, then FIG. 7A to FIG. 7B The results in were achieved at a dose temperature (Tb) of 41°C. It is currently believed that the buffer volume should be in the range of 300-2000ml, 300-1500ml or 300-1000ml, taking into account the normal consumption rate of treatment fluid during dialysis therapy. The method of using a relatively small buffer volume also ensures patient safety if the calculation model is slightly inaccurate. For example, if the dose temperature calculated by the calculation model has an error of ±1°C, the system will stabilize with a relatively small temperature error relative to the target temperature TT. This is FIG. 7C to FIG. 7D , where the dosage temperatures are 40°C and 42°C respectively.

[0119] There are many conceivable variations and extensions of the above technology, some of which will be described below.

[0120] In some embodiments, the temperature sensor is arranged in direct contact with the reservoir 50 (see Figure 1A to Figure 1B 53), preferably isolated from the environment, to measure the actual fluid temperature in the reservoir. This can allow closed-loop control and mitigate errors in energy losses determined by the computational model.

[0121] In some embodiments, the temperature of the fluid in the reservoir 50 is measured intermittently (e.g., every 30 minutes) by sending doses of fluid from the reservoir to a downstream temperature sensor (e.g., in the processing subsystem 6). In one implementation, the processing subsystem 6 includes a conductivity sensor including a temperature sensor that can be used to measure the temperature of the dosed fluid.

[0122] In some embodiments, the blood temperature is measured by a temperature sensor in contact with the blood downstream of the dialyzer 10, and the temperature of the fluid in the reservoir 50 is estimated based on the measured blood temperature.

[0123] In some embodiments, the temperature sensor for measuring the ambient temperature may be omitted, for example if the ambient temperature at the location of the dialysis system 1 is well controlled. Figure 1A of 80).

[0124] In some embodiments, the reservoir is provided with insulation, for example in the reservoir wall, by enclosing the reservoir in an insulated box or by attaching a multi-purpose insulating sleeve. Providing insulation will allow for lower dose temperatures, thereby improving patient safety.

[0125] The technology described herein allows manual control of the temperature of the fluid in the reservoir 50. The physician may choose to heat or cool the patient, depending on the patient's condition. For example, cooling may help avoid hemodynamic instability. Thus, a manual feedback loop may be implemented in which the physician measures the patient's temperature, decides whether heating or cooling is the best treatment option, and then adjusts the target temperature. In this way, static errors generated by the computational model may be overturned.

[0126] In some embodiments, the reservoir 50 is intermittently completely emptied of treatment fluid. For example, all fluid may be removed from the reservoir at fixed intervals (e.g., every 24 hours) to mitigate the risk of precipitation and / or microbial growth. Complete emptying of the reservoir enables the reservoir to be refilled with fluid at a known temperature, thereby resetting the estimate of the temperature of the fluid in the reservoir. The emptying may be accomplished gradually by allowing the fluid to be consumed by the dialysis therapy or by dumping the remaining fluid in the reservoir to drain. The amount of fluid present in the reservoir may be determined based on information from the scale 52 ( Figure 1A to Figure 1B )'s signal S2 is used to detect complete emptying of the reservoir 50.

[0127] In some embodiments, the gas may be released from the fluid in the reservoir. For example, as described above, carbon dioxide may be released from the treatment fluid as the temperature of the treatment fluid increases. The gas may be removed from the reservoir by any known method. In some embodiments, the gas is removed by completely emptying the reservoir, such as by continuing the emptying process for a certain period of time after detecting that all treatment fluid has been removed from the reservoir.

[0128] The temperature in the reservoir may not be uniform. The non-uniformity may be caused by hot fluid rising to the top of the reservoir and cooler fluid accumulating at the bottom. In addition, if the dose is introduced at the top of the reservoir and the fluid is drawn from the bottom, there is an increased risk of a temperature gradient forming in the reservoir. Several ways of mitigating this effect are described below.

[0129] In some embodiments, the dose is introduced at an entry point at the bottom of the reservoir 50 and the fluid is drawn from an exit point at the bottom of the reservoir 50, the entry point and the exit point are located separately and configured to promote mixing. In some embodiments, the dose flow rate is configured to cause movement within the fluid in the reservoir 50, thereby mixing. In some embodiments, the reservoir 50 includes an inlet nozzle for the dose, which is sized and / or shaped to promote mixing in the reservoir 50. In some embodiments, a small buffer volume is retained in the reservoir 50 to avoid the formation of a large stagnant fluid volume in the reservoir 50. As described above, the flow rate of the dose is configured to cause movement within the fluid in the reservoir 50, thereby promoting mixing. Fig. 7A The buffer volume is set as discussed above with respect to Figure 7d.

[0130] The dialysis therapy may be temporarily stopped, for example, due to various alarm conditions detected by the control device 7, actions required to care for the patient, or management actions such as replacing the fluid. In some implementations, the control device 7 may stop the processing subsystem 6 from removing fluid from the reservoir 50 to save the treatment fluid. However, the fluid temperature will drop during such a stop. In some embodiments, the control device 7 is instead configured to operate the processing subsystem 6 to remove fluid from the reservoir 50, and operate the supply subsystem 4 to also perform a fluid supply cycle when the dialysis therapy is temporarily stopped. This enables the temperature in the reservoir to be maintained at the target temperature and will help to restart the treatment. In an alternative embodiment, in order to save treatment fluid, the control device 7 is configured to calculate the temperature drop in the reservoir 50 during the treatment stop, and then operate the supply subsystem 4 with an increased dosage temperature to increase the fluid temperature in the reservoir 50 as soon as possible when the treatment is resumed. In another embodiment, the control device 7 is configured to completely drain the fluid in the reservoir 50 and operate the supply subsystem 4 to refill the reservoir 50 with fluid at a desired temperature if the temperature of the fluid in the reservoir 50 (measured or estimated) has dropped below a minimum limit. The minimum limit may be set to represent a fluid temperature that cannot be raised to the target temperature within a reasonable time.

[0131] The technique of controlling the temperature of fluid in a non-heated reservoir is not only applicable to treatment fluids. In some embodiments, the reservoir may instead contain water for dialysis therapy. Fig. 8A An example of such a dialysis system 1 is shown in FIG. The following description will focus on Figure 1A The differences compared to the dialysis system in. Fig. 8AThe dialysis system 1 in the embodiment includes a TF subsystem 3, a supply subsystem 4, a storage subsystem 5 and a processing subsystem 6, but Figure 1A The dialysis system 1 in FIG. 1 differs in that the supply subsystem 4 and the TF subsystem 3 are provided. Specifically, the supply subsystem 4 is configured to supply purified water for the dialysis system 1 . The supply subsystem 4 may or may not include a device for purifying the incoming water. Figure 1A Similarly, the supply subsystem 4 is operable to heat the fluid (purified water) by means of a heater 42 and to supply the dosed heated fluid to a reservoir 50 in the storage subsystem 5 via a path 4' by means of a pumping device 44. The processing subsystem 6 is operable to obtain purified water from the reservoir 50 via a path 5'. The TF subsystem 3 is included in the processing subsystem 6 and includes a mixing device for preparing a treatment fluid (TF) by mixing purified water with one or more concentrates. The flow control device 60 is configured to obtain TF from the TF subsystem 3 via a path 3' and to distribute TF according to the RRT performed by the processing subsystem 6.

[0132] Although Fig. 8A 1 is not shown, but the dialysis system 1 is operated by a control device, which can be operated according to Figure 1A The control device 7 is configured in. Thus, the control device 7 is configured to control the water temperature in the reservoir 50 to a target temperature. The target temperature can be set to achieve a specified temperature of the resulting treatment fluid.

[0133] Figure 8B Shown according to Fig. 8A right Figure 1BAdjustment of the dialysis system 1 in. The reservoir 50 contains purified water (indicated by W). In the example shown, the TF subsystem 3 is configured to produce a treatment fluid by mixing water with two liquid concentrates C', C" contained in respective containers 30a, 30b. Fluid paths 31a, 31b extend from the containers 30a, 30b to connection points 33a, 33b on the path 5'. The dialysis system 1 also includes a pumping device having a pump P5 in the fluid path 31a, a pump P6 in the fluid path 32b, and a pump P1 in the path 5' downstream of the connection points 33a, 33b. The pump P1 is arranged in the path 5' to limit the flow rate of the treatment fluid, and the pumps P5, P6 are arranged in the fluid paths 31a, 31b to limit the flow rates of C', C", respectively. Thus, pumps P5, P6 are operable to control the amount of C', C" that is mixed with the water within path 5'. In the example shown, the dialysis system 1 also includes a bypass path 16', which is fluidically connected to path 5' via a valve device 16. The bypass path 16' extends to the exhaust path 14 located upstream of the conductivity sensor 17. The dialysis system 1 can be operated in a calibration phase and a treatment phase. In the calibration phase, the valve device 16 is operated to direct fluid from path 5' into the bypass path 16', and the pumps P1, P5 and P6 are operated to produce different mixtures of W, C' and C" in path 5'. These mixtures are directed into the bypass path 16' and pass through the conductivity sensor 17. When the conductivity of the corresponding mixtures matches a predefined value, the relationship between the speeds of the pumps P1, P5, P6 is obtained to be used as calibration data for the treatment phase. During the treatment phase, valve means 16 is operated to direct fluid along path 5' into dialyzer 10, while pumps P1, P5 and P6 are operated according to calibration data to produce a treatment fluid having a specified composition. Figure 8B In the example shown, Figure 1B The disposable set in question further comprises fluid lines 31a, 31b which are detachably connected to the containers 30a, 30b via connectors 19f, 19g. The conductivity sensor 17 may or may not be included in the disposable set.

[0134] It is recognized that the concentrate C', C" may be at room temperature when mixed with the water from the reservoir 50, thereby reducing the temperature of the resulting treatment fluid relative to the water in the reservoir 50. In some embodiments, the control device 7 is configured to take this cooling effect into account when setting the target temperature of the water in the reservoir 50.

[0135] While the disclosed subject matter has been described in connection with what are presently considered to be the most practical embodiments, it is to be understood that the disclosed subject matter 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 scope of the appended claims.

[0136] Further, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results.

[0137] Appendix A

[0138] You can use Q h =h*A*ΔT describes the heat loss, where Q h is the heat dissipation per unit time [W], h is the heat transfer constant, and A is the surface area [m 2 ], and ΔT is related to the ambient temperature T a Since ΔT and A may vary with time, the equation is generalized to:

[0139] Q h (t) = h*A(t)*(T(t)-T a (t)) (1)

[0140] With a fixed surface area and containing a mass m r If a fluid is stored in a reservoir, assuming the ambient temperature is fixed, the temperature in the reservoir will decrease exponentially according to the following equation:

[0141]

[0142] Where c is the specific heat capacity of the fluid and T0 is the temperature at the reference time point t0.

[0143] Heat dissipation at any time Q h (t) can be calculated using Equation 1 and Equation 2 and can be integrated over time to calculate the total energy loss due to dissipation, E h :

[0144]

[0145] Assume that q c If a mass flow rate of 2 is used to remove fluid from the reservoir, the mass in the reservoir will change with time:

[0146] m r (t) = m r (t0)-q c ·t (4)

[0147] Here, t0 is the reference time point. It is assumed here that the fluid removal rate is constant, but it can alternatively be a function of time q c (t).

[0148] In one example, the heat dissipation area during the idle period is modeled assuming that the reservoir is spherical (e.g., if the reservoir is a bag made of a flexible material). For a sphere, the surface area is a function of the fluid volume V(t) in the reservoir:

[0149]

[0150] where ρ is the density of the fluid.

[0151] As a function of m r (t), more advanced models of A(t) or h·A(t), for example based on empirical data for a specific type of reservoir, can be envisioned.

[0152] The instantaneous energy loss of the reservoir due to fluid removal can be calculated as:

[0153]

[0154] In this calculation, the thermal energy content of the fluid is calculated as additional energy relative to the ambient temperature. In a variant, the thermal energy content can instead be calculated in absolute temperature [°K].

[0155] Based on Equation 6 and Equation 3, the total energy loss during the idle period (IP) from t = 0 to t = ts is given as follows:

[0156]

[0157] Depending on the system design, liquid removal can continue or stop during the dosing period (BP). In the following, it is assumed that the removal continues at the same flow rate q c The mass in the reservoir during the dosing period (ts < t < te) is:

[0158] m r (t) = m r (t0) - q c ·t + q b ·(t - ts) (8)

[0159] where q b is the mass flow rate of the dose and is also assumed to be constant during the dosing period. The heat dissipation area during the dosing period will result from Equations 5 and 8:

[0160]

[0161] The temperature in the reservoir will vary according to the mass and energy provided by the dose and the energy lost due to dissipation and fluid removal. During the dosing period (ts < t < te), the power and energy added to the reservoir by the dosing flow rate q b are given by the following equations:

[0162] Q b (t) = c·q b ·(T b -T b ) (10)

[0163]

[0164] The temperature of the fluid in the reservoir increases during the dosing period due to the energy supplied by the dose. Assuming complete mixing and temporarily neglecting energy losses during the dosing period, the energy content of the fluid in the reservoir is given by:

[0165] E r (t) = Ex (ts) + E b (t) = c·m r (t)·(T r (t)-T a ) (12)

[0166] Among them, E r (ts) is the energy content of the reservoir at the beginning of the dosing period:

[0167] E r (ts) = c·m r (ts)·(T r (ts)-T a ) (13)

[0168] The combination of Equation 11, Equation 12, and Equation 13 yields an equation for the temperature of the fluid in the reservoir:

[0169]

[0170] Equation 14 describes how the temperature in the reservoir increases during a dosing period due to the dose if energy losses during the dosing period are neglected.

[0171] The energy loss during the dosing period is given by the energy loss due to dissipation according to equation 3 and the energy loss due to fluid removal according to equation 6. These losses in turn depend on the temperature of the fluid in the reservoir. Therefore, it is more complicated to calculate the energy loss during the dosing period by analysis. However, the equation for calculating T(t) taking into account the energy loss during the dosing period is obtained by empirical estimation if not by analysis. Assuming that the equation for T(t) is available, the energy loss during the dosing period is given by the following equation:

[0172]

[0173] Finally, the total energy loss during a complete fluid cycle including the idle period and the dosing period is given by the following equation:

[0174]

Claims

1. A dialysis system comprising: a supply subsystem (4) configured to supply a fluid and comprising a heating device (42) for heating the fluid, a storage subsystem (5) comprising a non-heated reservoir (50), wherein the non-heated reservoir (50) is fluidically connected to receive the fluid from the supply subsystem (4) and is configured to contain an intermediate supply of fluid during operation of the dialysis system, a processing subsystem (6) configured to obtain the fluid from the storage subsystem (5) and perform a dialysis treatment using the fluid, and a control device (7) configured to operate the treatment subsystem (6) to perform the dialysis treatment, Wherein, the control device (7) is further configured to operate the supply subsystem (4) to perform a series of fluid supply cycles to cause a series of time-spaced doses of the fluid to be supplied to the non-heating reservoir (50), wherein corresponding fluid supply cycles in the fluid supply cycles are assigned a target temperature (TT) and include a predefined number of doses, wherein the supply subsystem (4) is operated to achieve the target temperature (TT) of the fluid in the non-heating reservoir (50) for the corresponding fluid supply cycles through the predefined number of doses.

2. The dialysis system according to claim 1, wherein: The target temperature (TT) is the temperature of the fluid in the non-heating reservoir (50) at a target time point within the corresponding fluid supply cycle, or is the time average of the temperature of the fluid in the non-heating reservoir (50) during the corresponding fluid supply cycle.

3. The dialysis system according to claim 1 or 2, wherein: The control device (7) is configured to: obtain the target temperature (TT); determine the energy content of the predefined number of doses to reach the target temperature (TT); and operate the supply subsystem (4) to prepare the fluid portion for producing the predefined number of doses according to the energy content.

4. The dialysis system according to claim 3, wherein: The control device (7) is configured to: determine a specified size of a corresponding dose in the predefined number of doses and a specified temperature of the corresponding dose, wherein the specified size and the specified temperature of the corresponding dose enable the predefined number of doses to have the energy content; operate the supply subsystem (4) to heat the fluid portion to the specified temperature by using the heating device (42); and operate the supply subsystem (4) to produce the corresponding dose having the specified size from the fluid portion having the specified temperature.

5. The dialysis system according to claim 4, wherein: The control device (7) is configured to: determine the amount of the fluid removed from the non-heating reservoir (50) by the processing subsystem (6) during the corresponding fluid supply cycle; and determining an energy content of the predefined number of doses based in part on the amount of the fluid removed from the non-heated reservoir (50).

6. The dialysis system according to claim 5, wherein: The control device (7) is configured to determine the specified size of the respective dose based on the amount of the fluid removed from the non-heated reservoir (50) during the respective fluid supply cycle.

7. The dialysis system according to claim 6, wherein: The control device (7) is configured to determine a specified temperature of the respective dose based on the specified size of the respective dose to achieve an energy content of the predefined number of doses.

8. The dialysis system according to any one of claims 3 to 7, wherein: The control device (7) includes a calculation model (400), which is configured to: estimate the total energy loss of the fluid in the non-heating reservoir (50) during the corresponding fluid supply cycle; and determine the energy content of the predefined number of doses based on the total energy loss during the corresponding fluid supply cycle.

9. The dialysis system according to claim 8, wherein: The total energy loss includes a first loss portion and a second loss portion, wherein the first loss portion represents the dissipated heat energy of the fluid in the non-heating reservoir (50), and the second loss portion represents the energy loss caused by the processing subsystem (6) removing the fluid from the non-heating reservoir (50).

10. The dialysis system according to claim 9, wherein: The total energy loss also includes a third loss portion representing the dissipated heat energy of the fluid in the flow path (4') extending from the supply subsystem (4) to the non-heating reservoir (50).

11. The dialysis system according to any one of claims 8 to 10, wherein: The control device (7) is capable of operating in a steady-state mode, in which the target temperature (TT) is the same for a plurality of consecutive fluid supply cycles, wherein the control device (7) in the steady-state mode is configured to set the energy content of the predefined number of doses to be equal to the total energy loss during the respective fluid supply cycle.

12. The dialysis system according to any one of claims 8 to 11, wherein: The computational model (400) is configured to: calculate the instantaneous temperature of the fluid in the non-heating reservoir (50) during the corresponding fluid supply cycle; and operate on the instantaneous temperature to determine the energy content of the predefined number of doses to achieve the target temperature (TT).

13. The dialysis system of claim 12, wherein: The control device (7) is configured to obtain a measurement value indicating the instantaneous temperature of the fluid in the non-heating reservoir (50) at a reference time point, wherein the calculation model (400) is configured to calculate the instantaneous temperature of the fluid in the non-heating reservoir (50) based on the measurement value.

14. The dialysis system of claim 13, wherein: The control device (7) is configured to: obtain a further measurement value indicating the instantaneous temperature of the fluid in the non-heating reservoir (50) at a time point after the reference time point; and adjust the calculated instantaneous temperature at the time point and / or the calculation model (400) based on the further measurement value.

15. The dialysis system according to any one of claims 12 to 14, wherein: The calculation model (400) is also configured to: calculate the instantaneous heat dissipation area of ​​the non-heating reservoir (50) and / or the instantaneous amount of the fluid in the non-heating reservoir (50); and estimate the instantaneous temperature based on the instantaneous heat dissipation area and / or the instantaneous amount of the fluid in the non-heating reservoir (50).

16. The dialysis system according to any one of claims 8 to 15, wherein: The control device (7) is configured to obtain input data used by the calculation model (400), the input data indicating the duration of the corresponding fluid supply cycle, the specific time of the corresponding dose within the corresponding fluid supply cycle, the duration of the corresponding dose, and the time curve of removing fluid from the non-heating reservoir (50) during the corresponding fluid supply cycle.

17. The dialysis system of claim 16, wherein: The control device (7) is configured to determine the time profile based on operational settings of the processing subsystem (6) or a measured flow rate of fluid entering the processing subsystem (6).

18. The dialysis system according to any one of claims 8 to 17, wherein: The corresponding dose is supplied to the non-heating reservoir (50) within a dose period (BP), wherein the calculation model (400) includes a function (411; 431) for estimating the energy loss of the non-heating reservoir (50) within the dose period (BP), and the function (413) takes into account the change in energy loss caused by the temperature change of the fluid in the non-heating reservoir (50), and the temperature change of the fluid in the non-heating reservoir (50) is caused by the supply of the corresponding dose.

19. The dialysis system according to any one of claims 3-18, further comprising an environmental sensor (80), which is arranged to measure the ambient temperature at the storage subsystem (5), and the control device (7) is configured to determine the energy content of the predefined number of doses based on the ambient temperature.

20. The dialysis system according to any one of the preceding claims, wherein: The control device (7) is configured to operate the supply subsystem (4) to perform the series of fluid supply cycles so that the temperature of the fluid in the non-heated reservoir (50) drops by less than about 5°C, 4°C, 3°C, 2°C or 1°C between consecutive doses.

21. A dialysis system according to any one of the preceding claims, wherein: The control device (7) is configured to operate the supply subsystem (4) to perform the corresponding fluid supply cycle having a duration greater than 5, 10 or 15 minutes and less than 30, 60 or 120 minutes.

22. A dialysis system according to any one of the preceding claims, wherein: The non-heated reservoir (50) is a disposable component.

23. A dialysis system according to any one of the preceding claims, wherein: The storage subsystem comprises a scale (5) for measuring the weight of the non-heated reservoir (50), and the control device (7) is configured to cause the supply subsystem (4) to supply the corresponding dose when the non-heated reservoir (50) has a predefined weight measured by the scale (5).

24. A dialysis system according to any one of the preceding claims, wherein: The control device (7) is configured to perform open-loop control on the supply subsystem (4) to achieve the target temperature (TT).

25. The dialysis system according to any one of claims 1 to 23, further comprising a measuring device (53) configured to measure a temperature value (TTa) of the fluid in the non-heated reservoir (50) corresponding to the target parameter (TT), wherein The control device (7) is configured to operate the supply subsystem (4) to adjust the size of the respective dose and / or the temperature of the fluid to be supplied by the respective dose based on the difference between the target temperature (TT) and the measured temperature value (TTa).

26. A dialysis system according to any one of the preceding claims, wherein: The fluid is a treatment fluid for the dialysis treatment.

27. A dialysis system according to any one of the preceding claims, wherein: The fluid is water, and the treatment subsystem (6) comprises a mixing device (3) configured to mix the fluid with one or more concentrates to provide a treatment fluid for the dialysis treatment.

28. A control device, said control device being included in a dialysis system according to any one of claims 1-27.

29. A computer-implemented method of operating a dialysis system, the dialysis system comprising a supply subsystem (4), a storage subsystem (5) and a processing subsystem (6), the method comprising: operating (202) the processing subsystem (6) to obtain fluid from the non-heated reservoir (50) in the storage subsystem (5) and perform a dialysis treatment using the fluid; as well as operating (203-205) the supply subsystem (4) to perform a series of fluid supply cycles to cause a series of time-spaced doses of the fluid to be supplied to the non-heated reservoir (50), wherein respective ones of the fluid supply cycles are assigned a target temperature (TT) and include a predefined number of doses, Wherein, the supply subsystem (4) is operated to achieve a target temperature (TT) of the fluid in the non-heating reservoir (50) for the corresponding fluid supply cycle through the predefined number of doses.

30. A computer readable medium comprising computer instructions which, when executed by a processing circuit (71), cause the processing circuit (71) to perform the method of claim 29.

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