Dialysis system with a filter test

Abstract

A peritoneal dialysis ("PD") system comprising a housing, a PD fluid pump housed within the housing, a filter set including a filter housing and a hydrophilic filter membrane that divides an upstream chamber within the filter housing from a downstream chamber, a dual lumen patient line including an unused PD fluid lumen in fluid communication with the upstream chamber and a used PD fluid lumen in fluid communication with the downstream chamber, a pressure sensor positioned and arranged to provide a pressure sensor output indicative of the pressure of the downstream chamber of the filter housing, and a control unit configured to perform a pressure integrity test of the hydrophilic filter membrane by monitoring the pressure sensor output over a period of time, wherein the pressure sensor output indicates a negative pressure applied to the downstream chamber by the PD liquid pump. A pressure drop test for evaluating the filter membrane is also disclosed.

Description

Technical Field

[0001] The present disclosure generally relates to medical fluid therapy, and more particularly to dialysate therapy that requires fluid heating.

Background Art

[0002] Due to various causes, a person's renal system may become dysfunctional. Renal insufficiency causes several physiological disorders. It is no longer possible to balance water and minerals and to excrete the daily metabolic load. The end products of metabolism that are toxic, such as urea, creatinine, and uric acid, can accumulate in the patient's blood and tissues.

[0003] Reduced kidney function, especially renal insufficiency, is treated by dialysis. Dialysis removes waste products, toxins, and excess water from the body that a normally functioning kidney would remove. Dialysis treatment as an alternative to kidney function is important for many people because the treatment can save lives.

[0004] One type of renal insufficiency treatment is hemodialysis ("HD"), which generally uses diffusion to remove waste products from the patient's blood. The diffusion gradient occurs across a semipermeable dialyzer between the blood and an electrolyte solution called dialysate or dialysis fluid that causes the diffusion.

[0005] Hemofiltration ("HF") is an alternative renal replacement therapy that convectively transports toxins from the patient's blood. HF is achieved by adding replacement fluid or substitution fluid to the extracorporeal circuit during treatment. The replacement fluid and fluid accumulated by the patient during treatment are ultrafiltered over the course of the HF treatment, providing a convective transport mechanism that is particularly beneficial in removing medium and large molecules.

[0006] Hemodiafiltration ("HDF") is a treatment modality that combines convective clearance and diffusive clearance. HDF uses dialysate flowing through a dialyzer, similar to standard hemodialysis, to provide diffusive clearance. Additionally, a replacement solution is provided directly to the extracorporeal circuit to provide convective clearance.

[0007] Most HD, HF, and HDF treatments are performed in a facility. Currently, there is a trend towards home hemodialysis ("HHD") because HHD can be performed daily and provides a therapeutic benefit over in-facility hemodialysis treatments, which are typically performed two or three times a week. Studies have shown that more frequent treatments remove more toxins and waste products and result in less interdialytic fluid overload than less frequent, but perhaps longer, treatments received by patients. Patients receiving more frequent treatments do not experience the downcycles (fluctuations in body fluid and toxins) experienced by patients in a facility who accumulate two to three days' worth of toxins prior to treatment. In certain areas, the nearest dialysis facility can be miles from the patient's home, consuming most of the day in door-to-door treatment time. Treatments at a facility close to the patient's home can also consume most of the patient's day. HHD can be performed at night or during the day while the patient is relaxed, working, or engaged in other productive activities.

[0008] Another type of kidney failure treatment is peritoneal dialysis ("PD"), which involves injecting a dialysis solution into the patient's peritoneal cavity via a catheter, also called the dialysis fluid. The dialysis fluid comes into contact with the peritoneum within the patient's peritoneal cavity. Waste products, toxins, and excess water enter the dialysis fluid from the patient's bloodstream through the peritoneal capillaries by diffusion and osmosis, i.e., an osmotic pressure gradient is generated across the membrane. Osmotic agents in the PD dialysis fluid provide the osmotic pressure gradient. The used or spent dialysis fluid is drained from the patient, removing waste products, toxins, and excess water from the patient. This cycle is repeated multiple times, for example.

[0009] There are various types of peritoneal dialysis treatments, including continuous ambulatory peritoneal dialysis (「CAPD」), automated peritoneal dialysis (「APD」), tidal flow dialysis, and continuous flow peritoneal dialysis (「CFPD」). CAPD is a manual dialysis treatment. Here, the patient manually connects an implanted catheter to the drain to enable draining of the used or spent dialysis fluid from the peritoneal cavity. Next, the patient switches the fluid communication so that the patient's catheter communicates with a bag of unused dialysis fluid and the unused dialysis fluid is infused into the patient through the catheter. The patient disconnects the catheter from the unused dialysis fluid bag and leaves the dialysis fluid in the peritoneal cavity where movement of waste products, toxins, and excess water is enabled. After the dwell period, the patient repeats the manual dialysis procedure, for example, four times a day. Manual peritoneal dialysis requires a significant amount of time and effort from the patient and leaves room for improvement.

[0010] Automated peritoneal dialysis (「APD」) is similar to CAPD in that the dialysis treatment involves cycles of drain, fill, and dwell. However, an automated PD machine typically performs the cycles automatically while the patient is sleeping. The PD machine is freed from the need to perform the treatment cycles manually and the need to transport supplies during the day. The PD machine makes fluid connections to an implanted catheter, a source or bag of unused dialysis fluid, and a fluid drain. The PD machine pumps unused dialysis fluid from the source of dialysis fluid through the catheter into the patient's peritoneal cavity. The PD machine also allows the dialysis fluid to dwell in a chamber to enable movement of waste products, toxins, and excess water. The source may contain multiple liters of dialysis fluid in several solution bags.

[0011] The PD machine pumps the used or spent dialysis fluid from the patient's peritoneal cavity through the catheter into the drain. As in the manual process, several drain, fill, and dwell cycles occur during dialysis. A 「last fill」 may occur at the end of an APD treatment. The last fill fluid may remain in the patient's peritoneal cavity until the next treatment is started or may be emptied manually at some point during the day.

[0012] In any of the above modalities, even automated machines and manual CAPD typically operate using disposable sets, which are discarded after a single use. Depending on the complexity of the disposable set, the cost of using one set per day can be significant. Also, everyday disposable items require storage space, which can be a nuisance for homeowners and businesses. Furthermore, daily replacement of disposable items requires daily setup time and effort by patients or caregivers at home or in a clinic.

[0013] For each of the above reasons, it is desirable to provide an APD machine that reduces disposable waste.

[0014] From US2020 / 0086028A1, a peritoneal dialysis (「PD」) system is also known that includes a housing and a pneumatic pump chamber that operates in a fluid pump chamber of a disposable cassette housed by the housing. The patient line includes a sterilization-grade filter having a hydrophilic filter membrane and a patient line that connects the filter to a PD pump. A pressure test of the filter membrane before delivery to the patient is readily available.

[0015] US2021 / 220539A1 discloses a control unit configured to evaluate a hydrophilic filter membrane by analyzing a pressure drop across the hydrophilic filter membrane.

[0016] WO2010 / 002830A2, US5275724A and US2019 / 0262525A1 disclose other dialysis machines according to the prior art. SUMMARY OF THE INVENTION

[0017] The present disclosure describes an automated peritoneal dialysis (「PD」) system including a PD machine or cycler. The PD machine can deliver heated unused PD fluid to a patient, for example, at 14 kPa (2.0 psig) or more. The PD machine can remove used PD fluid or waste fluid from the patient, for example, at -9 kPa (-1.3 psig) or more, such as between -5 kPa (-0.73 psig) and -15 kPa (-2.2 psig). The unused PD fluid may be delivered to the patient via a dual lumen patient line and first heated to the temperature of body fluid, for example, 37 °C. Then, the heated PD fluid passes through the unused PD fluid lumen of the dual lumen patient line, is pumped to a disposable filter set connected to the patient transfer set, and then is connected to an indwelling catheter leading to the patient's abdominal cavity. The disposable filter set is in fluid communication with the unused PD fluid lumen and the used PD fluid lumen of the dual lumen patient line. The disposable filter set is provided as a last chance filter for the PD machine in one embodiment, and the PD machine can be heat sterilized during treatment.

[0018] The system can include one or more PD fluid containers or bags that supply unused PD fluid to the PD machine or cycler. The PD machine or cycler can include an internal line having a two-way valve or three-way valve and at least one PD fluid pump for pumping unused PD fluid from one or more PD fluid containers or bags to the patient and removing used PD fluid from the patient to a house drain or drain container. One or more flexible PD fluid lines lead from the internal line of the PD machine or cycler to one or more PD fluid containers or bags. The flexible dual lumen patient line described above leads from the internal line of the PD machine or cycler to the patient. A flexible drain line leads from the internal line of the PD machine or cycler to a house drain or drain container. The system in one embodiment sterilizes all internal lines, PD fluid lines, and dual lumen patient lines after treatment for reuse in the next treatment. The sterilization can include heat sterilization using the remaining unused PD fluid.

[0019] To ensure that the filter set operates properly before and during treatment, it may be considered to perform at least one of a pressure drop test or a pressure integrity test on the hydrophilic membrane of the filter set. In one embodiment, the pressure integrity test is performed after priming the dual lumen patient line and the filter set before treatment. Then, during treatment, it may be considered to perform one or more pressure drop tests, for example, at the start of each patient fill.

[0020] A filter set in one embodiment includes a short flexible line extending downstream from the housing of the filter set, the hydrophilic filter membrane is present within the housing, and the housing divides into an upstream chamber (in fluid communication with the unused PD fluid lumen of the dual lumen patient line) and a downstream chamber (in fluid communication with the used PD fluid lumen of the dual lumen patient line). The upstream chamber comprises one or more hydrophobic membranes for allowing air to aseptically enter and exit the upstream chamber as desired. In one embodiment, the distal end of the short flexible line includes a connector that is capped during priming. In another embodiment, the short flexible line is connected to the patient transfer set during priming. In either case, air during priming can be trapped within the short flexible tube. As a result, removing air from the filter set including the dual lumen patient line and the short flexible tube involves multiple steps.

[0021] In a first step, a control unit of the PD system causes the PD fluid pump to pump unused PD fluid across a hydrophilic filter membrane and expels air (i) from the upstream chamber across at least one hydrophobic membrane and (ii) from the downstream chamber into a short flexible line to prime the filter set. In a second priming step, the control unit also causes the PD fluid pump to apply a negative pressure to the used PD fluid lumen, the downstream chamber, and the downstream line to remove air from the short flexible line and (i) draw unused PD fluid across the hydrophilic filter membrane to replace the air removed from the short flexible line and (ii) draw air into the upstream chamber across at least one hydrophobic membrane. In a third priming step, the control unit is further configured to remove air from the upstream chamber by causing the PD fluid pump to pump unused PD fluid into the upstream chamber and expel air from at least one hydrophobic membrane. After the third priming step, both chambers of the filter set and the short flexible line are fully primed (possibly containing a small amount of air).

[0022] Once the filter set, including the patient line and the short flexible line, is primed, before starting treatment, the control unit causes a pressure integrity test to be performed (alternatively, the pressure drop test described herein is performed at the end of priming). In the pressure integrity test, in one embodiment, the control unit causes the PD fluid pump to apply a negative pressure to the used PD fluid lumen of the dual lumen patient line and the downstream chamber of the filter housing. The negative pressure (i) draws unused PD fluid from the upstream chamber across the hydrophilic filter membrane into the downstream chamber, thereby (ii) drawing air into the upstream chamber across at least one hydrophobic membrane. Since the hydrophilic filter membrane is wet, air cannot move across the membrane. Thus, if the negative pressure is continuously applied, air fills the upstream chamber of the filter housing.

[0023] When the PD fluid is removed from the upstream chamber so that all or substantially all of the wet hydrophilic filter membrane is exposed to the air on its upstream surface, the negative pressure in the downstream chamber is set to the pressure of the desired integrity test, for example, -60 kPa (8.7 psig) to -90 kPa (13.1 psig), for example -75 kPa (10.9 psig). At that point, the control unit closes the valve necessary to lock the negative pressure in the downstream chamber, starts incrementing a timer while monitoring the output of one or more pressure sensors positioned and arranged to sense the set negative pressure. The pressure monitoring and the incrementing of the timer are performed for a desired duration sufficient to detect any leaks in the hydrophilic filter membrane, for example, at least 1 minute, for example, 90 seconds.

[0024] During the monitoring period, if the measured -75 kPa (10.9 psig) does not "drop" (become less negative) by more than the tolerance, for example, 2.5 kPa (0.36 psig), the control unit determines that the hydrophilic filter membrane is intact and allows, for example, treatment to proceed until the first patient drain or patient fill. However, if during that period the measured -75 kPa (10.9 psig) "drops" (becomes less negative) by more than the tolerance, for example, 2.5 kPa (0.36 psig), the control unit determines that the hydrophilic filter membrane is damaged and causes the user interface to provide an audible, visual, or audiovisual alarm or warning to inform the patient that the filter set is defective and needs to be replaced.

[0025] It is possible to perform a pressure integrity test at one or more additional times during treatment. However, instead, the system of the present disclosure may perform a pressure drop test on the hydrophilic filter membrane one or more times during treatment, for example, at the start of each patient fill. The pressure drop test is easier to perform and involves monitoring, by a plurality of pressure sensors, at least one measured pressure upstream of the hydrophilic filter membrane and at least one measured pressure downstream of the hydrophilic filter membrane. An intact hydrophilic filter membrane is expected to cause a slight pressure drop, which is likely to increase over time due to the type of PD fluid being pumped. For example, a higher pressure drop occurs for the last filled PD fluid, such as icodextrin or a higher glucose PD fluid. Also, as the filter membrane accumulates fibrin, protein, and other substances from the patient's effluent on its downstream side and accumulates bacteria from filtration on its upstream side, the pressure drop increases. Therefore, it is conceivable that the control unit causes the PD fluid pump to flush at least the downstream surface of the filter membrane with unused PD fluid after each drain and remove solid effluent for the drain before the start of the next patient fill.

[0026] For the pressure drop test, take a plurality of upstream and downstream pressure drop readings, calculate the plurality of pressure drops over a period of, for example, several seconds, derive an average or mean pressure drop, and compare this to an acceptable pressure drop range or a minimum expected pressure drop. In an embodiment, if the average or mean pressure drop is outside the acceptable pressure drop range or below the minimum acceptable value, the control unit stops the treatment and causes the user interface to provide an audible, visual, or audiovisual alarm, or alert, informing the patient that the filter set is defective and needs to be replaced. If the average or mean pressure drop is within the acceptable pressure drop range or above the minimum acceptable pressure drop, the control unit allows the treatment to proceed.

[0027] Based on the disclosure described in this specification, without limiting the present disclosure in any way, in a first aspect of the present disclosure, any or all of the structures and / or functionalities of any of claims 1 to 21 can be combined with any or all of the structures and / or functionalities of any other of claims 1 to 21. In a second aspect of the present disclosure that can be combined with any part or all of the first aspect, any of the features, functionalities, and alternatives described in relation to any one or more of FIGS. 1 to 15 can be combined with any of the features, functionalities, and alternatives described in relation to any other of FIGS. 1 to 15.

[0028] Based on the above aspects described in this specification and the present disclosure, it is an advantage of the present disclosure to provide structures and functionalities that ensure that the hydrophilic filter is intact and ready for use.

[0029] Another advantage of the present disclosure is to provide structures and functionalities that allow the hydrophilic filter to be tested before and / or during use.

[0030] A further advantage of the present disclosure is to provide structures and functionalities that allow the hydrophilic filter to be tested using different tests.

[0031] Yet another advantage of the present disclosure is to provide structures and functionalities that allow the hydrophilic filter to be tested using existing equipment.

[0032] Additional features and advantages will be apparent from the following detailed description and drawings. The features and advantages described herein are not all-inclusive, and in particular, many additional features and advantages will be apparent to those skilled in the art in view of the drawings and description. Also, any particular embodiment need not have all of the improvements or advantages listed herein, and it is clearly contemplated that individual advantageous embodiments may be claimed separately. In particular, the systems of the present disclosure may have any one or more or all of the structures and methodologies of the filter pressure drop test, the patient line including the structures and methodologies of filter set priming, and the structures and methodologies of the filter pressure integrity test described herein. Further, it should be noted that the language used herein has been selected primarily for readability and for explanatory purposes, and is not intended to limit the scope of the subject matter of the invention.

Brief Description of the Drawings

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DETAILED DESCRIPTION OF THE INVENTION

[0037] System Overview Referring now to the drawings, and in particular to FIG. 1, a medical system having enhanced features of the present disclosure is shown via a peritoneal dialysis ("PD") system 10. The system 10 includes a PD machine or cycler 20 and a control unit 100 having one or more processors 102, one or more memories 104, a video controller 106, and a user interface 108. The user interface 108 may alternatively or additionally be a remote user interface via, for example, a tablet or smartphone. The control unit 100 also includes a transceiver and a network (not shown), such as a wired or wireless connection to the Internet, for transmitting treatment data to a server of a physician or clinician that interfaces with a computer of the physician or clinician and receiving prescription instructions / changes from the server of the physician or clinician. The control unit 100 in one embodiment controls all of the electro-fluidic flows and heating components of the system 10 and receives the output from all of the sensors of the system 10. The system 10 in the illustrated embodiment includes components that are durable and reusable components that contact unused PD fluid and used PD fluid, which requires that the PD machine or cycler 20 be sterilized during treatment, for example, via heat sterilization.

[0038] The system 10 in FIG. 1 includes an in-line resistance heater 56, reusable supply lines or tubes 52a1 - 52a4, 52b, an air trap 60 operative with each of upper and lower level sensors 62a, 62b, an air trap valve 54d, a vent valve 54e positioned along a vent line 52e, a reusable line or tube 52c, a PD fluid pump 70, temperature sensors 58a, 58b, pressure sensors 78a, 78b1, 78b2, 78c, reusable patient tubes or lines 52f, 52g having valves 54f, 54g respectively, a dual lumen patient line 28, a hose reel 80 for storing the patient line 28, a reusable drain tube or line 52i extending to a drain line connector 34 and having a drain line valve 54i, and reusable recirculation sterilization tubes or lines 52r1, 52r2 operative with sterilization valves 54r1, 54r2 respectively. A third recirculation or sterilization tube or line 52r3 extends between sterilization or PD fluid line connectors 30a and 30b for use during sterilization. A fourth recirculation or sterilization tube or line 52r4 extends between sterilization connectors 30c and 30d for use during sterilization.

[0039] The system 10 also includes PD fluid containers or bags 38a - 38c (e.g., holding the same or different formulations as the PD fluid) connected to the distal ends 24e of reusable PD fluid lines 24a - 24c respectively. The system 10d further includes a fourth PD fluid container or bag 38d connected to the distal end 24e of a reusable PD fluid line 24d. The fourth PD fluid container or bag 38d may hold a PD fluid of the same or different type (e.g., icodextrin) as that provided within the PD fluid containers or bags 38a - 38c. The reusable PD fluid lines 24a - 24d extend through an opening (not shown) defined or provided by the housing 22 of the cycler 20 in one embodiment.

[0040] In the illustrated embodiment, system 10 includes four sterilization or PD fluid line connectors 30a - 30d for connection to the distal ends 24e of reusable PD fluid lines 24a - 24d, respectively, during sterilization. System 10 also provides a patient line connector 32 that includes an internal lumen, such as a U - shaped lumen, which, for sterilization, directs unused or used dialysate from one PD fluid lumen of the connected distal end 28e of dual - lumen patient line 28 to the other PD fluid lumen. Reusable supply tubes or lines 52a1 - 52a4 communicate with reusable supply lines 24a - 24d, respectively. Reusable supply tubes or lines 52a1 - 52a3 operate with valves 54a - 54c, respectively, to enable drawing PD fluid into cycler 20 from desired PD fluid containers or bags 38a - 38c. The three - way valve 94a in the illustrated example enables the control unit 100 to select between (i) 2.27% (or other) glucose dialysate from container or bag 38b or 38c and (ii) icodextrin from container or bag 38d. In the illustrated embodiment, the icodextrin from container or bag 38d is connected to the normally - closed port of three - way valve 94a.

[0041] In one embodiment, system 10 is configured such that drain line 52i is fluidly connected downstream of PD fluid pump 70 during patient fill. In this way, during patient fill of patient P, if drain valve 54i fails or a leak occurs for any reason, instead of used PD fluid being drawn into pump 70, fresh PD fluid is pushed out into disposable drain line 36. In one embodiment, disposable drain line 36 is removed for sterilization, and drain line connector 34 is capped via cap 34c to form a closed sterilization loop. PD fluid pump 70 may be an essentially accurate pump, such as a piston pump, or a less - accurate pump, such as a gear pump, that operates in cooperation with a flow meter (not shown) for controlling the flow rate and volume of unused and used PD fluid.

[0042] System 10 may further include a leak detection pan 82 located at the bottom of the housing 22 of the cycler 20 and a corresponding leak detection sensor 84 that outputs to the control unit 100. In the illustrated example, system 10 includes an additional pressure sensor 78c located upstream of the PD fluid pump 70, which enables measurement of the suction pressure of the pump 70 and helps the control unit 100 more accurately determine the pump volume. The additional pressure sensor 78c in the illustrated embodiment may be filled with air or a mixture of air and PD fluid, but nevertheless should be located along a vent line 52e that is at the same negative pressure as the PD fluid located within the PD fluid line 52c.

[0043] The system 10 of the example of FIG. 1 includes redundant pressure sensors 78b1, 78b2, the output of one of which is used for pump control as discussed herein, and the output of the other pressure sensor is a safety or monitoring output to ensure that the control pressure sensor is accurately read. The pressure sensors 78b1, 78b2 are located along a line that includes the third recirculation valve 54r3. The system 10 may further use one or more cross joints marked with an X in FIG. 1 that can (i) reduce the overall amount and volume inside the internal reusable tube, (ii) reduce the number of valves required, and (iii) minimize the portion of the fluid circuit shared by both unused and used PD fluid.

[0044] System 10 in the example of FIG. 1 further includes an acid source, such as a citric acid container or bag 66. The citric acid container or bag 66 is selectively in fluid communication with a second three-way valve 94b via a citric acid valve 54m located along a citric acid line 52m. In one embodiment, the citric acid line 52m is connected to the normally closed port of the second three-way valve 94b, providing a redundant valve between the citric acid container or bag 66 and the PD fluid circuit during treatment. The redundant valve ensures that citric acid (or other acid) does not reach the treatment fluid line during treatment. Instead, citric acid (or other acid) is used during sterilization.

[0045] In an embodiment, the control unit 100 uses feedback from any one or more of the pressure sensors 78a - 78c to enable the PD machine 20 to deliver heated unused PD fluid to the patient, for example, at 14 kPa (2.0 psig) or more. The pressure feedback is used to enable the PD machine 20 to remove used PD fluid or waste fluid from the patient, for example, between -5 kPa (-0.73 psig) and -15 kPa (-2.2 psig), for example, between -9 kPa (-1.3 psig) or more (more negative). The pressure feedback can be used in a proportional, integral, derivative ("PID") pressure routine to pump the unused and used PD fluids at a desired positive or negative pressure.

[0046] The in-line resistance heater 56 under the control of the control unit 100 can heat the unused PD fluid to body temperature, for example, 37°C, for delivery to the patient P at a desired flow rate. In an embodiment, the control unit 100 uses feedback from a temperature sensor 58a in a PID temperature routine to pump the unused PD fluid to the patient P at a desired temperature.

[0047] FIG. 1 also shows that the system 10 includes a disposable filter set 40 that is in fluid communication with the unused PD fluid lumen and the used PD fluid lumen of the dual lumen patient line 28, indicating its use. The disposable filter set 40 includes a disposable connector 42 that connects to the distal end 28e of the reusable patient line 28. The disposable filter set 40 also includes a connector 44 that connects to the patient transfer set. The disposable filter set 40 also includes a hydrophilic filter membrane 46 that can be of a sterilization grade and further filters the unused PD fluid. In one embodiment, the disposable filter set 40 is provided as a last chance filter for the PD machine 20 that has been heat sterilized during treatment. Although unlikely, pathogens remaining after sterilization are filtered from the PD fluid through the hydrophilic filter membrane 46 of the disposable filter set 40.

[0048] FIG. 1 shows a setup of the system 10 for treatment using PD fluid containers or bags 38a - 38d connected via reusable flexible PD fluid lines 24a - 24d, respectively. The dual lumen patient line 28 is connected to the patient P via the disposable filter set 40. The disposable drain line 36 is connected to the drain line connector 34. In FIG. 1, the PD machine or cycler 20 of the system 10 is configured to perform a plurality of patient drain, patient fill, patient dwell, and priming procedures as part of, or in preparation for, treatment.

[0049] Figure 2 shows the system 10 in the sterilization mode. The PD fluid containers or bags 38a - 38d are removed, and the flexible PD fluid lines 24a - 24d are instead inserted and sealed to the sterilization or PD fluid line connectors 30a - 30d, respectively. The reusable dual - lumen patient line 28 is disconnected from the disposable filter set 40 (to be discarded), and the distal end 28e of the dual - lumen patient line 28 is inserted and sealed to the patient line connector 32. The disposable drain line 36 is removed from the drain line connector 34 and discarded. The drain line connector 34 is capped via the cap 34c to form a closed sterilization loop 90. The PD machine or cycler 20 of the system 10 in FIG. 2 is configured to execute a sterilization sequence, for example, a heat sterilization sequence in which unused PD fluid is heated to a sterilization temperature, for example, 70 °C to 90 °C, via the in - line heater 56. The PD fluid pump 70 circulates the closed sterilization loop 90 of the heated PD fluid for the time required to properly sterilize the fluid components and lines of the sterilization loop.

[0050] Pressure Drop Test Referring again to FIG. 1, the control unit 100 may perform a pressure drop test at one or more desired times before and / or during treatment to ensure that the hydrophilic filter membrane 46 of the disposable filter set 40 is functioning properly. The pressure drop test requires fluid to flow through the filter membrane 46. While the fluid, for example, PD fluid, flows through the filter membrane 46, pressure measurements are taken upstream and downstream of the filter membrane 46. In FIG. 1, the output from the pressure sensor 78a can be used as the upstream pressure measurement value, while the output from any one or more of the pressure sensors 78b1, 78b2 can be used as the downstream pressure measurement value.

[0051] The pressure drop test can be performed at least during priming of the PD machine or cycler 20, the reusable PD fluid lines 24a - 24d, and the internal line of the reusable patient line 28. During priming, the patient line 28 is connected to the patient P via a disposable filter set 40 and a patient transfer set in one embodiment, which may be open or closed. Priming may be done such that the disposable filter set 40 is not yet connected to the patient P, instead of having connectors capped at the ends of the flexible line or tube 50 (see FIGS. 3 - 7). In either case, the control unit 100 pumps unused PD fluid from the PD fluid containers or bags 38a - 38d, through the unused patient tube or line 52f, through the unused PD fluid lumen of the dual lumen patient line 28, and through the filter set 40 including the filter membrane 46 via the PD fluid pump 70. Here, the control unit 100 opens or toggles one of the PD fluid valves 54a - 54c or 94a, opens valves 54d and 54f, and closes valve 54g. In one embodiment, air is pushed out from the hydrophobic vent 48 (see FIGS. 3 - 7) provided in the filter set 40. The unused PD fluid is heated to the patient's body temperature, e.g., 37°C, during the pressure drop test, and as a result, the pressure drop is recorded under treatment conditions.

[0052] It should be understood that prior to the first drain, the used PD fluid lumen of the dual lumen patient line 28 may be mainly filled with air. However, as the PD fluid is pushed across the filter membrane, the air is compressed by the pressure of the PD fluid downstream of the filter membrane 46 of the filter set 40. Thus, the downstream pressure sensors 78b1, 78b2 accurately read the pressure downstream of the filter membrane 46 even when partially or fully contacted by air.

[0053] The pressure for the determination of the pressure drop and the determination itself are carried out over a period sufficient to ensure that the determined pressure drop is steady and accurate, for example, over 1 to 5 seconds. During this time, multiple sets of readings of the upstream and downstream pressure drops can be taken, and multiple pressure drop calculations may be performed. The multiple pressure drop calculations may be averaged, or the average pressure drop during the calculations may be regarded as the pressure drop used for comparison with the acceptable pressure drop range.

[0054] In an embodiment, if the average or mean pressure drop is outside the acceptable pressure drop range, or below the minimum acceptable value, the control unit 100 stops the treatment and causes the user interface 108 to provide an audio, video or audiovisual alarm, or alert, to inform the patient that the filter set 40 is defective and needs to be replaced. If the average or mean pressure drop is within the acceptable pressure drop range, or above the minimum acceptable pressure drop, the control unit 100 enables the treatment to proceed. In an embodiment, the minimum acceptable pressure drop or pressure drop range at the start of the treatment is assumed to be such that the hydrophilic filter membrane 46 is in a state similar to that of a new one.

[0055] As described above, the valve in the patient transfer set can be opened and closed during the pressure drop test performed during priming. Or, the filter set 30 may be disconnected from the patient transfer set during priming. Performing the pressure drop test during priming with the transfer set valve open liberates the patient from the burden of having to remember that the valve must be opened during treatment. However, performing the pressure drop test during priming with the transfer set connected and the transfer set valve open means that the flow of the PD fluid is split, with part of the flow returning to the PD machine or cycler 20 via the used PD fluid lumen of the dual lumen patient line and part of the flow of the PD fluid going towards the patient.

[0056] In addition to priming, it is conceivable to perform subsequent pressure drop tests one or more times during treatment, for example, at the start of each patient fill using a PD machine or cycler 20. Again here, pressure measurements upstream and downstream of the filter membrane 46 are taken while the PD fluid flows through the filter membrane 46. In FIG. 1, the output from the pressure sensor 78a can be reused as the upstream pressure measurement value, while the outputs from one or more pressure sensors 78b1, 78b2 can be reused as the downstream pressure measurement values.

[0057] During each patient fill, the patient line 28 is connected to the patient P via the disposable filter set 40 and the patient transfer set, which may be open or closed. The control unit 100 pumps unused PD fluid from one of the PD fluid containers or bags 38a - 38d through the unused patient tube or line 52f, through the unused PD fluid lumen of the dual lumen patient line 28, through the filter set 40 including the filter membrane 46, through the patient transfer set, and into the patient's peritoneal cavity via the PD fluid pump 70. Here, the control unit 100 opens or toggles one of the PD fluid valves 54a - 54c or 94a and opens the valves 54d and 54f. The used PD fluid valve 54g is closed. The unused PD fluid is heated to the patient's body temperature, for example 37°C, during patient fill.

[0058] Often, after priming, the first treatment operation is to remove the last fill of the used PD fluid from patient P. In such cases, the used PD fluid lumen of the dual lumen patient line 28 is filled with the used PD fluid for each patient fill and each pressure drop test during treatment. If there is no last fill to remove from the patient, such that the first treatment operation is the first patient fill, the used PD fluid lumen of the dual lumen patient line 28 can be mainly filled with air. However, again, the air is compressed by the pressure of the PD fluid downstream from the filter membrane 46 of the filter set 40 as the PD fluid is pushed across the filter membrane. Thus, the downstream pressure sensors 78b1, 78b2 accurately read the pressure downstream from the filter membrane 46 even when partially or fully contacted by air during the first patient fill.

[0059] The pressure and the determination itself for determining the pressure drop during treatment can be made over a period sufficient to ensure that the determined pressure drop is steady and accurate, for example, over 1 - 5 seconds. During this time, the control unit 100 that monitors the pressure sensors 78a, 78b1, 78b2 can take multiple sets of readings of the upstream and downstream pressure drops, and multiple calculations of the pressure drop may be performed. The multiple calculations of the pressure drop may be averaged, or the average pressure drop during the calculations may be considered the pressure drop used for comparison with the acceptable range of pressure drops.

[0060] Similar to priming, if the average or mean pressure drop during treatment is outside the acceptable range of pressure drops, or below the minimum acceptable value, the control unit 100 stops the treatment and causes the user interface 108 to provide an audible, visual, or audiovisual alarm, or alert, informing the patient that the filter set 40 is defective and needs to be replaced. If the average or mean pressure drop is within the acceptable range of pressure drops, or above the minimum acceptable pressure drop, the control unit 100 enables the current patient fill to proceed.

[0061] The pressure drop across the hydrophilic filter membrane 46 is expected to increase over the course of treatment. The pressure drop can increase due to the type of PD fluid being pumped, e.g., a higher pressure drop for the last fill PD fluid, e.g., icodextrin or a higher glucose PD fluid. The pressure drop increases as the filter membrane 46 accumulates fibrin, protein, and other substances from the patient's effluent on its downstream side and bacteria from the filtration on its upstream side. It is contemplated that the control unit 100 flushes at least the downstream surface of the filter membrane 46 with unused PD fluid after each drain and removes solid effluent for the drain prior to the start of the next patient fill with the PD fluid pump 70. The flush in one embodiment involves pushing a small amount of unused PD fluid, e.g., 5 to 50 milliliters, across the filter membrane 46 to remove solid effluent from its downstream surface and then removing and discharging the small amount of PD fluid containing the removed effluent. However, even with a post-drain flush, it is contemplated that the control unit 100 may have to raise the minimum allowable pressure drop or pressure drop range over the course of treatment for use in comparison to the measured pressure drop.

[0062] Priming / Pressure Integrity Test Referring now to FIGS. 3-15, immediately after priming, in addition to, or instead of, the pressure drop test, the control unit 100 may cause, for example, a integrity test of the sterilization grade hydrophilic filter membrane 46 to be performed. FIGS. 3-10 show one suitable priming sequence for the dual lumen patient line 28 and the filter set 40. FIGS. 3-10 show that the filter set 40 includes a filter housing 40h that holds the hydrophilic filter membrane 46 in a sealed state so as to form an upstream chamber 40u and a downstream chamber 40d that are respectively upstream and downstream of the filter membrane 46. The filter housing 40h includes a connector 42 that connects to the distal end 28e of the reusable patient line 28 and a connector 44 that connects to a short flexible line or tube 50 that extends to a connector 64c of a patient transfer set, or in one embodiment, the patient transfer set 64 (FIG. 8).

[0063] FIGS. 3-10 also show that the filter housing 40h includes one or more hydrophobic membranes or vents 48 along the upstream chamber 40u, allowing air to be pushed out of or primed from the filter housing. For example, the sterilization grade filter membrane 46 may be made of a hydrophilic material having a pore size of about 0.2 microns through which unused PD fluid flows for further filtration in one embodiment. The filter membrane 46 may be made, for example, of polysulfone or polyethersulfone mixed with polyvinylpyrrolidone. The one or more hydrophobic membranes 48 may be made, for example, of polytetrafluoroethylene (“PTFE”).

[0064] Figure 3 shows the first priming step in which the control unit 100 causes an appropriate valve to open and pumps unused PD fluid from the PD fluid containers or bags 38a - 38d through the unused PD fluid lumen of the dual lumen patient line 28 into the upstream chamber 40u of the filter housing 40h and brings it into contact with the upstream side of the filter membrane 46. Air in the upstream chamber 40u is pushed out of the filter housing through one or more hydrophobic membranes or vents 48. As long as the air is dry, it can move through the hydrophilic filter membrane 46. However, Figure 4 shows that the filter membrane 46 quickly gets wet and pushes the air out only through one or more hydrophobic membranes 48.

[0065] Figures 5 - 7 show that when the upstream chamber 40u of the filter housing 40h is completely filled with unused PD fluid, the unused PD fluid is pushed out (filtered) through the filter membrane 46 into the downstream chamber 40d of the filter housing 40h. Figure 7 shows both the upstream and downstream chambers completely filled with unused PD fluid.

[0066] Figure 8 shows that air from the downstream chamber 40d is pushed into a short flexible line or tube 50 that extends to the patient transfer set 64. To remove the air pushed into the short flexible line or tube 50, in FIG. 9, the control unit 100 closes the unused PD fluid valve 54f and opens the used PD fluid valve 54g and the drain valve 54i. The control unit 100 applies a negative pressure to the PD fluid pump 70 that is used in the PD fluid lumen 28u of the dual lumen patient line 28. The negative pressure (i) draws the air in the short flexible line or tube 50 into the used PD fluid lumen 28u and (ii) draws ambient air into the upstream chamber 40u of the filter housing 40h through one or more hydrophobic membranes 48. The air entering the upstream chamber 40u then pushes unused PD fluid through the hydrophilic filter membrane 46 into the short flexible line or tube 50 in place of the outgoing air. Thus, in one embodiment, the filter housing 40h and the short flexible line or tube 50 are configured such that the volume of the upstream chamber 40u is equal to or greater than the internal volume of the short flexible line or tube 50 so that there is sufficient unused PD fluid to fill the flexible tube.

[0067] Figure 10 shows that the next step is for the control unit 100 to close the used PD fluid valve 54g and the drain valve 54i and open the unused PD fluid valve 54f and an appropriate PD fluid valve. The control unit 100 then refills the upstream chamber 40u with unused PD fluid in the PD fluid pump 70 and purges air to the atmosphere through one or more hydrophobic membranes or vents 48. At the end of the procedure of FIG. 10, both the filter housing 40h and the short flexible line or tube 50 are completely filled with unused PD fluid (e.g., a small amount of air less than 1 cubic centimeter may remain).

[0068] For ease of explanation, FIGS. 8-10 show the used PD fluid lumen 28u of the dual lumen patient line 28 extending from the short flexible line or tube 50. However, it should be understood that the used PD fluid lumen 28u may instead be disposed in fluid communication directly with the downstream chamber 40d of the filter housing 40h. As shown in FIG. 1, the used PD fluid lumen 28u may be connected to the disposable connector 42 along with the unused PD fluid lumen 28f, and the connector 42 includes an internal port extending into the downstream chamber 40d that enables the used PD fluid lumen 28u to communicate with the downstream chamber 40d.

[0069] FIGS. 11-15 show one embodiment for the integrity or pressure holding test of the system 10 of the present disclosure, which may exist after priming instead of the pressure drop test described above, although the pressure drop test is still performed during treatment, for example, at the start of each patent fill. In the pressure integrity test of FIGS. 11-15, a filter housing 40h filled with PD fluid on both sides of the hydrophilic filter membrane 46 is used, and the wet membrane forms a complete wall of air. For the integrity test, the control unit 100 closes the unused PD fluid valve 54f so that the unused PD fluid lumen 28f of the dual lumen patient line 28 is closed. The control unit 100 also opens the used PD fluid valve 54g and the drain valve 54i, and causes the PD fluid pump 70 to draw a negative pressure into the downstream chamber 40d via the used PD fluid lumen 28u, the used PD fluid line 52g, the line 52c, and the drain line 52i.

[0070] In an embodiment, the pressure for the integrity or pressure hold test is from -60 kPa (8.7 psig) to -90 kPa (13.1 psig), for example -75 kPa (10.9 psig). FIGS. 11-13 show that the control unit 100 can initially operate the PD fluid pump 70 at a higher speed to more rapidly increase the negative pressure in the downstream chamber 40d. FIG. 11 shows the initial application of the negative pressure. FIGS. 12 and 13 show that the negative pressure draws the PD fluid from the upstream chamber 40u across the hydrophilic filter membrane 46 into the downstream chamber 40d. The control unit 100, in one embodiment, uses the outputs from at least one of the pressure sensors 78b1, 78b2 as feedback to know the negative pressure in the downstream chamber 40d.

[0071] In FIG. 14, when the measured negative pressure approaches the target value pressure for the integrity test, the control unit 100 in the embodiment significantly slows down the PD fluid pump 70 until the negative pressure in the downstream chamber 40d reaches the target value pressure, for example, -75 kPa (10.9 psig). FIG. 14 also shows that almost all of the PD fluid has been discharged from the upstream chamber 40u across the hydrophilic filter membrane 46 into the downstream chamber 40d.

[0072] In FIG. 15, when the target pressure is reached, the control unit 100 stops the PD fluid pump 70 and causes a integrity or pressure hold test to be performed (with the used PD fluid valve 54g and drain valve 54i open or closed). As shown in FIG. 15, the upstream chamber 40u is at zero kPa (zero psig) due to accessing the atmosphere via one or more hydrophobic membranes or vents 48, and the downstream chamber 40d is maintained at a target pressure, e.g., -60 kPa (8.7 psig) to -90 kPa (13.1 psig), e.g., -75 kPa (10.9 psig). Thus, a relatively large pressure differential exists across the filter membrane 46, which is worth checking for any leaks within the membrane. In the integrity or pressure hold test of the present disclosure, the control unit 100 monitors the output from at least one pressure sensor 78b1, 78b2 over a specified period, e.g., at least 1 minute or 90 seconds. If the measured -75 kPa (10.9 psig) does not "drop" (minus decreases) by more than an allowable amount, e.g., 2.5 kPa (0.36 psig) over that period, the control unit 100 determines that the hydrophilic filter membrane 46 is intact and allows, for example, treatment to continue until the first patient drain or patient fill. However, if the measured -75 kPa (10.9 psig) "drops" (minus decreases) by more than an allowable amount, e.g., 2.5 kPa (0.36 psig) over that period, the control unit 100 determines that the hydrophilic filter membrane 46 is damaged and causes the user interface 108 to provide an audible, visual, or audiovisual alarm or warning to inform the patient that the filter set 40 is defective and needs to be replaced.

[0073] The integrity or pressure holding test of the system 10 of the present disclosure is considered to be capable of detecting holes or breaks with a nominal diameter of 10 to 20 μm. If no such holes or breaks are found and the hydrophilic filter membrane 46 is determined to be intact, the control unit 100 repeats the procedure of FIG. 10, the PD fluid pump 70 refills the upstream chamber 40u with unused PD fluid, and purges air to the atmosphere through one or more hydrophobic membranes or vents 48. The filter housing 40h and the short flexible line or tube 50 are both filled with unused PD fluid, and the hydrophilic filter membrane 46 is ready for treatment.

[0074] It will be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Accordingly, this type of change and modification is intended to be covered by the appended claims. For example, the system 10 for any of the improved treatment features discussed herein need not use redundant components or components with durability, and instead, a disposable set having a disposable pump section in contact with the corresponding medical fluid may be used. For example, in a system without heat sterilization, the disposable filter set 40 is not required as a last chance filter, but if unused PD fluid is made online during use, the disposable filter set 40 can still be provided as a last chance filter for the online PD fluid. The pumping of the PD fluid in the disposable set may instead be performed via the operation of a pneumatic pump of the sheet of the disposable cassette of the disposable set, via the operation of an electromechanical pump of the sheet of the disposable cassette of the disposable set, or via the operation of a peristaltic pump of the pumping tube segment provided with the disposable set.

Claims

Claim 1 A peritoneal dialysis ("PD") system (10), comprising a housing (22), a PD fluid pump (70) housed in the housing (22), a filter set (40) including a hydrophilic filter membrane (46), a dual lumen patient line (28) in fluid communication with the PD fluid pump (70), the dual lumen patient line (28) including an unused PD fluid lumen (28f) in fluid communication upstream of the hydrophilic filter membrane (46) and a used PD fluid lumen (28u) in fluid communication downstream of the hydrophilic filter membrane (46), a first pressure sensor (78a) positioned and arranged to provide a first pressure sensor output indicative of the PD fluid pressure in the unused PD fluid lumen (28f), a second pressure sensor (78b1, 78b2) positioned and arranged to provide a second pressure sensor output indicative of the PD fluid pressure in the used PD fluid lumen (28u), a control unit (100) configured to evaluate the hydrophilic filter membrane (46) by analyzing a pressure drop across the hydrophilic filter membrane (46), the pressure drop including a difference between the second pressure sensor output and the first pressure sensor output, The PD system (10) comprising the above components. Claim 2 The PD system (10) according to claim 1, wherein the control unit (100) is configured to evaluate that the hydrophilic filter membrane (46) is intact when the pressure drop is equal to or greater than a minimum pressure drop or within an acceptable pressure drop range. Claim 3 The PD system (10) according to claim 2, wherein the minimum pressure drop or the acceptable pressure drop range increases over the course of treatment. Claim 4 The PD system (10) according to any one of claims 1 to 3, wherein the control unit (100) is configured to evaluate that the hydrophilic filter membrane (46) is damaged when the pressure drop is less than the minimum pressure drop or outside the acceptable pressure drop range. Claim 5 The PD system (10) according to any one of claims 1 to 4, wherein the pressure drop includes an average of a plurality of differences between the plurality of second pressure sensor outputs and the plurality of first pressure sensor outputs.

6. The PD system (10) according to any one of claims 1 to 5, wherein the pressure drop includes an average pressure drop derived from a plurality of differences between the plurality of second pressure sensor outputs and the plurality of first pressure sensor outputs.

7. The PD system (10) according to any one of claims 1 to 6, wherein the control unit (100) is configured to evaluate the hydrophilic filter membrane (46) by analyzing the pressure drop across the hydrophilic filter membrane (46) during at least one patient fill of PD treatment.

8. The PD system (10) according to any one of claims 1 to 7, wherein the control unit (100) is configured to cause the PD fluid pump (70) to drain flush PD fluid across the hydrophilic filter membrane (46) after at least one patient drain and before the at least one patient fill.

9. The PD system (10) according to any one of claims 1 to 8, wherein the control unit (100) is configured to evaluate the hydrophilic filter membrane (46) by performing a pressure integrity test of the hydrophilic filter membrane (46) prior to PD treatment.

10. The PD system (10) according to any one of claims 1 to 9, wherein the pressure integrity test includes programming the control unit (100) to (i) cause a pressure differential across the hydrophilic filter membrane (46) with the PD fluid pump (70), and (ii) monitor at least one of the first pressure sensor output and the second pressure sensor output to detect a change in the pressure differential.

11. The PD system (10) according to any one of claims 1 to 10, wherein the filter set (40) includes at least one hydrophobic membrane (48), and the control unit (100) is configured to perform the pressure integrity test after priming the filter set (40), and priming the filter set (40) includes discharging air through the at least one hydrophobic membrane (48).

12. A peritoneal dialysis ("PD") system (10), a housing (22), a PD fluid pump (70) housed in the housing (22), a filter set (40) including a filter housing (22) and a hydrophilic filter membrane (46) that divides an upstream chamber (40u) in the filter housing (22) from a downstream chamber (40d), a dual-lumen patient line (28) in fluid communication with the PD fluid pump (70), the dual-lumen patient line (28) including an unused PD fluid lumen (28f) in fluid communication with the upstream chamber (40u) and a used PD fluid lumen (28u) in fluid communication with the downstream chamber (40d), pressure sensors (78b1, 78b2) positioned and arranged to provide a pressure sensor output indicative of the pressure in the downstream chamber (40d) of the filter housing (22), a control unit (100) configured to perform a pressure integrity test of the hydrophilic filter membrane (46) by monitoring the pressure sensor output over a certain period of time, the pressure sensor output indicating a negative pressure generated in the downstream chamber (40d) by the PD fluid pump (70), A PD system (10) comprising.

13. The PD system (10) according to claim 12, wherein the negative pressure generated in the downstream chamber (40d) is a negative PD liquid pressure.

14. The PD system (10) according to claim 12 or 13, wherein the negative pressure is -60 kPa (8.7 psig) to -90 kPa (13.1 psig), for example -75 kPa (10.9 psig), and the certain period of time is at least 1 minute.

15. The PD system (10) according to any one of claims 12 to 14, wherein the upstream chamber (40u) is maintained at atmospheric pressure during the pressure integrity test.

16. The PD system (10) according to claim 15, wherein the filter housing (22) includes at least one hydrophobic membrane (48) forming part of the upstream chamber (40u), and the atmospheric pressure is enabled by the hydrophobic membrane (48).

17. The PD system (10) according to claim 16, wherein the control unit (100) causes a negative pressure to be generated in the downstream chamber (40d) by applying a negative pressure to the used PD fluid lumen (28u) and the downstream chamber (40d) of the PD fluid pump (70), and is configured such that the PD fluid is drawn from the upstream chamber (40u) into the downstream chamber (40d) across the hydrophilic filter membrane (46), and the PD fluid drawn from the upstream chamber (40u) is replenished through air passing through the hydrophobic membrane (48).

18. The PD system (10) according to any one of claims 15 to 17, wherein the control unit (100) is configured to prime the filter set (40) including a line (50) extending downstream from the filter set (40) before performing the pressure integrity test.

19. The PD system (10) according to claim 18, wherein the control unit (100) is configured to prime the filter set (40) by pumping unused PD fluid across the hydrophilic filter membrane (46) to the PD fluid pump (70), thereby (i) pushing the air in the upstream chamber (40u) across the at least one hydrophobic membrane (48), and (ii) pushing the air in the downstream chamber (40d) to the downstream line (50).

20. The PD system (10) according to claim 19, wherein the control unit (100) applies a negative pressure to the PD fluid pump (70), to the used PD fluid lumen (28u), the downstream chamber, and the downstream line (50), so that (i) unused PD fluid is drawn across the hydrophilic filter membrane (46) to replace the air removed from the downstream line (50), and (ii) air is drawn into the upstream chamber (40u) across the at least one hydrophobic membrane (48), and is further configured to remove air from the downstream line (50).

21. The PD system (10) according to claim 20, wherein the control unit (100) is further configured to discharge air from the at least one hydrophobic membrane (48) and remove air from the upstream chamber (40u) by pumping unused PD fluid into the upstream chamber (40u) by the PD fluid pump (70).

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