Search

EP-4739368-A1 - GENERATING MEDICAL FLUID FOR RENAL REPLACEMENT THERAPY

EP4739368A1EP 4739368 A1EP4739368 A1EP 4739368A1EP-4739368-A1

Abstract

A system is configured to generate a medical fluid for renal replacement therapy by on-line mixing of fluids. The system comprises a first flow path (12), a second flow 5 path (16), a first sensor (20) in the first flow path, and a second sensor (20') in the second flow path. The first and second sensors measure a composition-related parameter. The system is operable to convey at least one of the fluids to the first and second sensors in a calibration phase, and determine a conversion function for converting between a first signal of the first sensor and a second signal of the second 0 sensor, based the first and second signals during the calibration phase. In a production phase, the system is operable to control at least one pump based on converted measurement values given by operating the conversion function on measurement values in the first signal from the first sensor.

Inventors

  • BORGQVIST, Per-Olof
  • JANSSON, OLOF
  • PETTERSSON, Michael
  • FORS, Jonas

Assignees

  • Gambro Lundia AB

Dates

Publication Date
20260513
Application Date
20240627

Claims (20)

  1. 1. A system for generating a medical fluid for renal replacement therapy, said system comprising: a first flow path (12) for receiving and mixing at least two fluids to form the medical fluid; a pump arrangement (4) for pumping the at least two fluids through the first flow path (12); a first sensor (20, 20a), which is arranged in the first flow path (12) to provide a first signal (SI, SI a) indicative of a composition-related parameter; a valve arrangement (15) operable to selectively open a passage from the first flow path (12) to a second flow path (16); a second sensor (20'), which is arranged in the second flow path (16) to provide a second signal (SI 1 ) indicative of the composition-related parameter; and a control device (40) configured to: operate, in a calibration phase (CP), the valve arrangement (15) and the pump arrangement (4) to convey at least one of the at least two fluids to the first and second sensors (20, 20a; 20'); determine, based on the first and second signals (SI, SI a; SI') during the calibration phase, a conversion function for converting measurement values in the first signal (SI, SI a) into measurement values in the second signal (SI'); and operate, in a production phase (PP), the valve arrangement (15) and the pump arrangement (4) to pump the at least two fluids through the first flow path (12) to provide the medical fluid at an outlet (12a), wherein at least one pump (P2; P3) in the pump arrangement (4) is controlled based on converted measurement values given by operating the conversion function on the measurement values in the first signal (SI; Sla) from the first sensor (20; 20a) during the production phase (PP).
  2. 2. The system of claim 1, wherein the first sensor (20, 20a) is a disposable component and the second sensor (20') is a re-usable component.
  3. 3. The system of claim 1 or 2, wherein the second sensor (20') is configured to be retained in the system and used in a repetition of the calibration phase when the first sensor (20, 20a) has been discarded and replaced for a new first sensor (20, 20a), wherein the repetition of the calibration phase results in an updated conversion function for converting the measurement values in the first signal (SI, Sla) of the new first sensor (20, 20a) into the measurement values in the second signal (SI 1 ) of the second sensor (20').
  4. 4. The system of any preceding claim, wherein the second sensor (20') has a higher accuracy than the first sensor (20, 20a).
  5. 5. The system of any preceding claim, which comprises a machine (lb) and a disposable arrangement (la) releasably engaged with the machine (lb), wherein the machine (lb) includes the pump arrangement (4) and the valve arrangement (15), and wherein the disposable arrangement (la) defines the first flow path (12) and the second flow path (16), and wherein the first sensor (20, 20a) is included in the disposable arrangement (la).
  6. 6. The system of any preceding claim, wherein the control device (40), in the calibration phase (CP), is configured to: operate the pump arrangement (4) to generate a set of test fluids from said at least two fluids; operate the pump arrangement (4) and the valve arrangement (15) to convey a respective test fluid in the set of test fluids to the first and second sensors (20, 20a; 20'); obtain a first measurement value for the respective test fluid from the first signal (SI, SI a); obtain a second measurement value for the respective test fluid from the second signal (ST); and determine the conversion function based on the first and second measurement values for the respective test fluid.
  7. 7. The system of claim 6, wherein at least one test fluid in the set of test fluids comprises a mixture of the at least two fluids.
  8. 8. The system of claim 7, wherein the control device (40), in the calibration phase (CP), is configured to operate the pump arrangement (4) to generate said at least one test fluid to achieve a target value in the second signal (ST) from the second sensor (20').
  9. 9. The system of any one of claims 6-8, wherein one test fluid in the set of test fluids is the medical fluid.
  10. 10. The system of any one of claims 6-9, wherein control device (40), in the calibration phase (CP), is configured to operate the pump arrangement (4) to generate the set of test fluids by providing a first fluid (Fl) among the at least two fluids as an initial test fluid, and by sequentially adding another fluid among the at least two fluids to the initial test fluid, to generate a corresponding sequence of test fluids, until all fluids among the at least two fluids have been added to the initial test fluid.
  11. 11. The system of claim 10, wherein the first fluid (Fl) is water, and wherein each of said another fluid is added in a proportion equal to its proportion in the medical fluid.
  12. 12. The system of any one of claims 6-11, wherein the control device (40) is configured to determine the conversion function by fitting a predefined function to the first and second measurement values for the set of test fluids.
  13. 13. The system of any preceding claim, wherein the first sensor (20, 20a) is located upstream of the valve arrangement (15) in the first flow path (12), so that the first and second sensors (20, 20a; 20') are fluidly connected in series when the valve arrangement (15) is operated to open the passage from the first flow path (12) to the second flow path (16).
  14. 14. The system of any preceding claim, wherein the control device (40), in the production phase, is configured to: intermittently operate the valve arrangement (15) to open the passage to the second flow path (16) and direct the medical fluid to the second sensor (20'); obtain a current first measurement value for the medical fluid from the first signal (SI, SI a); obtain a current second measurement value for the medical fluid from the second signal (SI'); evaluate the current first and second measurement values for detection of a deviation; and take dedicated action upon detection of the deviation.
  15. 15. The system of claim 14, wherein the control device (40) is configured to: operate the conversion function on the current first measurement value to generate a current converted measurement value; and evaluate the current second measurement value and the current converted measurement value for detection of the deviation.
  16. 16. The system of claim 14 or 15, wherein the dedicated action comprises at least one of generating an alarm, or performing the calibration phase (CP) to determine an updated conversion function.
  17. 17. The system of any preceding claim, wherein the control device (40), in the production phase (PP), is configured to monitor the speeds of pumps in the pump arrangement (4) for detection of changes indicative of operational error.
  18. 18. The system of any preceding claim, said at least two fluids comprise a liquid concentrate.
  19. 19. The system of claim 18, which is configured to generate the liquid concentrate from a dry concentrate.
  20. 20. The system of any preceding claim, wherein the control device (40), in the production phase (PP), is configured to control the pump arrangement (4) to generate the medical fluid at a target flow rate, while maintaining the converted measurement values at a target value of the composition-related parameter.

Description

GENERATING MEDICAL FLUID FOR RENAL REPLACEMENT THERAPY Technical Field The present disclosure relates to the field of renal replacement therapy and in particular to generation of a medical fluid for use in such therapy. Background Art Renal replacement therapy (RRT) is a therapy that replaces the normal bloodfiltering function of the kidneys. It is used when the kidneys are not working well, which is known as kidney failure and includes acute kidney injury (AKI) and chronic kidney disease (CKD). RRT involves removal of water from the blood of the patient suffering from kidney failure, as well as exchange of solutes with the blood. One example of RRT is extracorporeal blood therapy, in which blood is circulated outside of the patient and interfaced with one or more medical fluids. Modalities 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 peritoneal cavity of the patient to interface with the blood of the patient through the peritoneal membrane. Medical fluids used in HD and PD are commonly known as dialysis fluids. In HF, the medical fluid is known as replacement fluid, since it is infused into the blood of the patient to replace fluid removed during therapy. In HDF, both dialysis fluid and replacement fluid are used. Extracorporeal blood therapy by HD, HF or HDF is performed differently for treatment of patients with AKI compared to patients with CKD, by use of a different type of dialysis machine. Generally, compared to CKD patients, AKI patients are treated continuously over a longer period of time and at lower fluid flow rates. Such continuous treatment is commonly known as CRRT (Continuous Renal Replacement Therapy). To ensure precise and consistent monitoring and control of fluid removal, known as ultrafiltration, AKI machines are typically provided with scales that are used for measuring the weight of fresh treatment fluid and the weight of spent treatment fluid during therapy. CKD machines instead use flow meters or volumetric pumping to control ultrafiltration. PD machines, also known as cyclers, 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. Over time, RRT consumes large quantities of medical fluid. In some modalities of RRT, pre-made medical fluid is delivered in prefilled bags to the point of care. For example, conventional PD is performed by use of prefilled bags. AKI machines are configured to use prefilled bags of medical fluid, by staff arranging a prefilled bag on one of the scales before treatment, and replacing the prefilled bag as required. On the other hand, CKD machines have integrated capability to generate medical fluid on- demand by mixing one or more concentrates with water, so-called on-line fluid generation. Recently, PD machines with integrated capability of on-line fluid generation have been proposed. There is a general desire to advance on-line generation of medical fluid for all types of RRT. Given the installed base of dialysis machines, it would also be desirable to provide a simple technique of re-configuring existing dialysis machines to produce their own medical fluid. Summary It is an objective to at least partly overcome one or more limitations of the prior art. A further objective is to expand the number of machines that may be used for online generation of medical fluid for RRT. Another objective is to enable accurate on-line generation of medical fluid at low cost. One or more of these objectives, as well as further objectives that may appear from the description below, are at least partly achieved by a system for generating medical fluid for renal replacement therapy, a control method, a computer-readable medium, and a disposable arrangement, embodiments thereof being defined by the dependent claims. Still other objectives and aspects, as well as embodiments, features and technical advantages, may appear from the following detailed description, from the attached claims as well as from the drawings. Brief Description of the Drawings FIG. l is a schematic diagram of an example system for generating medical fluid. FIG. 2 A is a flow chart of an example method of operating the system of FIG. 1, and FIG. 2B is a flow chart of an example implementation of a data collection step in the method of FIG. 2 A. FIG. 3 is a graph of calibration data obtained during a calibration phase. FIG. 4 is schematic diagram of a control system for generating a control signal for a pump in the system of FIG. 1. FIGS 5A-5B are schematic diagrams of a disposable arrangement and a machine, respectively, for use in the system of FIG. 1. FIG. 6 is a schematic diagram of a variant of the system in FIG. 1. FIG. 7 is a flow chart of a method of operating the system in FIG. 6. FIG. 8 is a flow char