Peritoneal dialysis system having air-assisted pumping sequence - Patents.com

Abstract

Disclosed herein is a peritoneal dialysis ("PD") system having an air-assisted pumping sequence. In one embodiment, the PD system includes a housing, a PD fluid pump contained in the housing, an air trap, a fluid line extending from the air trap, a fluid line valve positioned and arranged to operate with the fluid line, a gas line extending from a top of the air trap, and a gas line valve positioned and arranged to operate with the gas line. The system also includes a control unit configured to close the fluid line valve, open the gas line valve, and cause the PD fluid pump to pump gas from the air trap into the gas line after patient drain, forming a pocket of gas in the fluid line and forcing remaining spent PD fluid towards the drain line.

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates generally to medical fluid treatment, and more particularly, to dialysis fluid treatment. [Background technology]

[0002] (background) Due to a variety of causes, a person's renal system can fail. Renal failure leads to a variety of physiological abnormalities. It is no longer possible to balance fluids and minerals or to excrete the daily metabolic load. Toxic end products of metabolism such as urea, creatinine, and uric acid can accumulate in the patient's blood and tissues.

[0003] Reduced kidney function, especially kidney failure, is treated with dialysis, which removes waste products, toxins, and excess fluid from the body that would be removed by normally functioning kidneys. Kidney replacement dialysis is a potentially life-saving procedure and is therefore very important to many people.

[0004] One renal failure therapy is hemodialysis ("HD"), which typically uses diffusion to remove waste products from a patient's blood. A diffusion gradient is created between the blood and an electrolyte solution called the dialysis fluid, or dialysis fluid, which induces diffusion, through a semi-permeable dialyzer.

[0005] Hemofiltration ("HF") is an alternative renal replacement therapy that relies on convective transport of toxins from the patient's blood. HF is achieved by adding replacement or substitution fluid to the extracorporeal circuit during treatment. The replacement fluid, and fluid that accumulates in the patient during treatment, is ultrafiltered during the course of the HF treatment, providing a convective transport mechanism that is particularly beneficial for the removal of middle and large molecules.

[0006] Hemodiafiltration ("HDF") is a treatment that combines convective and diffusive clearance. HDF, like standard hemodialysis, uses dialysis fluid flowing through a dialyzer to provide diffusive clearance. In addition, replacement solution is delivered directly to the extracorporeal circuit to provide convective clearance.

[0007] Most HD, HF, and HDF procedures are performed in centers. There is currently a movement toward home hemodialysis ("HHD") in part because HHD can be performed daily, which offers therapeutic advantages over in-center hemodialysis procedures, which are typically performed once every 2 to 3 weeks. Studies have shown that patients who have more frequent treatments have more toxins and waste products removed and experience less fluid overload during dialysis than patients who have fewer treatments but longer treatment times. Patients who have more frequent treatments do not experience down-cycling (fluctuations in fluids and toxins) as do in-center patients who build up 2 to 3 days' worth of toxins before treatment. In some areas, the nearest dialysis center may be many miles away from the patient's home, resulting in door-to-door treatment times consuming a large portion of the patient's day. Even treatments at centers closer to the patient's home can consume a large portion of the patient's day. HHD is performed at night or during the day while the patient is relaxing, working, or engaged in other productive activities.

[0008] Another form of renal failure therapy is peritoneal dialysis ("PD"), in which a dialysis solution, also called dialysis fluid, is infused through a catheter into a patient's peritoneal cavity. The dialysis fluid contacts the peritoneal membrane in the patient's peritoneal cavity. Waste, toxins, and excess water flow from the patient's bloodstream through the capillaries in the peritoneal membrane and into the dialysis fluid by diffusion and osmosis, i.e., the osmotic gradient across the peritoneal membrane. An osmotic agent in the PD dialysis fluid creates the osmotic gradient. Spent or exhausted dialysis fluid is pumped out of the patient, removing the waste, toxins, and excess water from the patient. This cycle may be repeated, for example, multiple times.

[0009] There are various types of peritoneal dialysis therapy, including continuous ambulatory peritoneal dialysis ("CAPD"), automated peritoneal dialysis ("APD"), tidal peritoneal dialysis, and continuous flow peritoneal dialysis ("CFPD"). CAPD is a manual dialysis procedure in which the patient manually connects an implanted catheter to a drain so that used or exhausted dialysis fluid is drained from the peritoneal cavity. The patient then switches the fluid communication so that the patient's catheter is in communication with a bag of new dialysis fluid, and new dialysis fluid is infused through the catheter into the patient. The patient removes the catheter from the bag of new dialysis fluid, allowing the dialysis fluid to dwell in the peritoneal cavity where waste products, toxins, and excess water are transported. After the dwell time, the patient repeats the manual dialysis procedure, for example, four times a day. Manual peritoneal dialysis requires a great deal of time and effort from the patient, and there is ample room for improvement.

[0010] Automated peritoneal dialysis ("APD") is similar to CAPD in that the dialysis treatment includes drain, fill, and dwell cycles. However, these cycles are performed automatically by the APD device, usually while the patient sleeps. APD devices free the patient from having to perform the treatment cycles manually and from carrying medical supplies during the day. The APD device is fluidly connected to an implanted catheter, a source or bag of fresh dialysis fluid, and a fluid drain. The APD device pumps fresh dialysis fluid from the dialysis fluid source through the catheter and into the patient's peritoneal cavity. The APD device also allows the dialysis fluid to dwell in a chamber to transport waste, toxins, and excess water. The source can contain several liters of dialysis fluid, including several solution bags.

[0011] The APD machine pumps used or exhausted dialysis fluid through a catheter and out of the patient's peritoneal cavity. As with manual dialysis treatments, drain, fill, and dwell cycles are repeated several times during dialysis. At the end of an APD treatment, a "final fill" may be performed. The final fill fluid may remain in the patient's peritoneal cavity until the start of the next treatment, or it may be manually emptied at some point during the day.

[0012] In any of the above methods of using automated devices, the automated devices usually work with a disposable set and are discarded after a single use. Depending on the complexity of the disposable set, the cost of using one set per day can be large. Also, daily disposables require storage space and can be a nuisance for homes and businesses. Furthermore, changing daily disposables requires time and effort for the patient or caregiver to set up each day at home or in the clinic.

[0013] For each of the above reasons, it would be desirable to provide an APD device that reduces disposable waste, thereby eliminating disposable items and preserving as much of the flow path as possible in terms of reusing the flow path. Thus, there is a need for improved reusable or durable PD fluid systems. Summary of the Invention [Means for solving the problem]

[0014] (summary) Known automated peritoneal dialysis ("PD") systems typically include a machine or cycler that accepts and operates a pumping cassette having a rigid section and a flexible section that is deformable for pumping and valving. The rigid section is attached to tubing that extends to various bags. For the patient at home, loading the disposable cassette and associated tubing and bags for a treatment can be cumbersome. Also, with so many disposable items, there are numerous set-up steps that the patient must enter, leaving room for error.

[0015] In contrast, in the disclosed APD system and related techniques, many of the fluid-carrying parts of the PD system are converted into reusable components that are disinfected after treatment. The fluid lines in the device or cycler are reused. Other disposable items include a drain bag or drain line leading to a house drain, and one or more PD fluid containers or bags, such as PD fluid containers with various dextrose or glucose levels, and a final bag container, such as icodextrin. In one embodiment, a disposable filter is placed at the distal end of the patient line to provide a final stage of PD fluid filtration before delivery to the patient.

[0016] The APD system of the present disclosure includes an APD cycler with a housing. At least one, and possibly three or more, reusable PD fluid lines extend from the housing. When not connected to a PD fluid container or bag, the reusable PD fluid lines can be connected to a disinfection connector supported and provided by the housing. The reusable PD fluid lines can extend, for example, from the front of the housing and can be connected to a disinfection connector provided at the front of the housing for ready access to the PD fluid lines. The reusable PD fluid lines can be color coded and / or keyed to match the color coded or keyed connectors of the PD fluid container or bag. The container or bag can hold PD fluids with different glucose or glucose levels, such as 1.36% glucose PD fluid, 2.27% glucose PD fluid, and / or final bags of different formulations of PD fluid, such as icodextrin.

[0017] Inside the housing, reusable tubing extends from each of the reusable PD fluid lines through a PD fluid line valve for each PD fluid line to an in-line heater for the PD fluid. In one embodiment, each valve of the APD cycler is an electrically actuated valve having a reusable valve body that blocks the PD fluid (e.g., when not energized) or allows the PD fluid to flow through it (e.g., when energized). In one embodiment, the in-line heater for the PD fluid is also electrically actuated, e.g., a resistive heater having a reusable heater body that receives the PD fluid for heating. The in-line heater in one embodiment is capable of heating the PD fluid from room temperature to body temperature, e.g., 37° C., at a flow rate of at least 200 milliliters ("ml") / min. A temperature sensor is positioned adjacent to the heater, e.g., downstream of the heater, to provide feedback for temperature control.

[0018] In one embodiment, a reusable tube extends from the outlet of the PD fluid in-line heater to the air trap. Any tubes in the cycler housing can be made of metal, such as stainless steel, or plastic, such as polyvinyl chloride ("PVC") or non-PVC materials, such as polyethylene ("PE"), polyurethane ("PU"), polycarbonate ("PC"), polyetheretherketone ("PEEK"). In one embodiment, one or more level sensors are positioned adjacent to the air trap so that a desired level, or desired level range, of PD fluid is maintained in the air trap. In one embodiment, a fluid line valve is positioned along the reusable fluid line downstream of the air trap and operates in cooperation with a gas line valve positioned along the gas line, as described herein. The air trap can be closed upstream by the PD fluid line valve to vent the air trap when required by the output of the level sensor.

[0019] The reusable PD fluid pump is disposed within the cycler housing and includes a reusable pump body that receives the PD fluid for pumping, i.e., the pump does not require the PD fluid to flow through a disposable item such as a tube or cassette. The PD fluid pump can be a motorized piston pump, which is inherently accurate and does not require a separate PD fluid volume control device, such as a balance chamber or device using the ideal gas law. The PD fluid pump can instead be a motorized gear pump or centrifugal pump that can operate with a separate PD fluid volume control device.

[0020] By controlling the current level to the PD fluid pump, the PD fluid pump can be controlled to pump to or from the patient at or below a pressure limit. The patient's positive pressure limit can be, for example, 1 to 5 psig (e.g., 2 psig (14 kPa)). The patient's negative pressure limit can be, for example, -1.0 psig to -3.0 psig (e.g., -1.3 psig (-9 kPa)). In one embodiment, the PD fluid pump is bidirectional and continuous and can be a single pump.

[0021] The APD cycler of the APD system according to the present disclosure includes a control unit having one or more processors and one or more memories that receive signals or outputs from the pressure, temperature, and possibly conductivity sensors and process the signals or output them as feedback. The control unit uses pressure feedback to control a PD fluid pump to operate at safe patient pressure limits during treatment and at safe system limits during disinfection. The control unit uses temperature feedback to control a PD fluid heater to heat new PD fluid, for example to body temperature.

[0022] Additionally, the control unit performs a priming sequence, a patient fill sequence, a patient drain sequence, and a disinfection sequence after a PD treatment by opening and closing the PD fluid valves in cooperation with the PD fluid pump and heater, where each of the at least one reusable PD fluid lines is connected to one of the at least one disinfection connectors, and the reusable patient line is connected to the reusable patient line connector. The disinfection sequence prepares the APD cycler for the next treatment. In one embodiment, unused fresh PD fluid is heated after the final drain and used for disinfection.

[0023] In one embodiment, after the patient drain is complete, the control unit opens the gas line valve and closes the fluid line valve, causing the PD fluid pump 70 to draw a small amount (e.g., 0.5 ml or more) of air or gas (or mixture) above the air trap from the top of the air trap. The PD fluid pump can operate in one or more pumping strokes to draw the desired volume of gas. The control unit also opens the exhaust line valve, causing the PD fluid pump to push air bubbles through the reusable fluid line toward the exhaust line connector. The moving air bubbles push residual waste or drain fluid from the previous patient drain toward the exhaust line connector and into the house or container drain.

[0024] To avoid creating negative pressure in the air trap, the control unit may open one or more PD fluid line valves to allow an equal volume of new PD fluid to enter the air trap while the air pocket is being removed from the air trap. The control unit may also monitor the output from the upper level sensor to ensure that new PD fluid is not drawn from the air trap into the gas line. If air is detected at the upper level sensor while the formation of the air pocket is in progress, the control unit in one embodiment closes the gas line valves and stops the PD fluid pump.

[0025] After the gas pocket is formed and introduced, the control unit closes the gas line valves, opens the fluid line valves, and opens one or more PD fluid supply line valves (if not already open). The PD fluid pump then forces the gas pocket toward the exhaust line connector, thereby forcing the residual effluent or used PD fluid toward the exhaust line 36 and into the house or container drain, where the new PD fluid is upstream of the gas pocket and the residual used PD fluid or effluent is downstream of the gas pocket. It is contemplated that the control unit may have the PD fluid pump pump the new PD fluid that pushes the gas pocket 68 at a slower rate to create a laminar flow of fluid that is less likely to disrupt the formation of the gas pocket.

[0026] In an alternative embodiment of the disclosed system, a filtered vent is added that can draw air from the environment and exhaust unwanted gases (e.g., CO2, air, or a mixture thereof) to the environment. The filtered vent in one embodiment includes a hydrophobic filter membrane, e.g., 0.2 microns, configured to provide sterile filtration of the environmental air entering through the filtered vent.

[0027] The filtered vent is used across multiple procedures, but is replaced, for example, between services, since it poses a greater risk of microorganisms than the filter membranes associated with the disposable filter sets of the patient lines described herein. It is therefore contemplated that the vent line leading to the filtered vent communicates with a fluid location in the system that is not part of the patient circuit during a procedure, either for patient fill or patient drain. In the disclosed system, a bypass line is provided that extends between multiple possible locations, namely the disinfection connector. The bypass line shown and described below is isolated during a procedure and is not fluidly connected to the patient.

[0028] By fluid-tightly connecting the distal end of the reusable PD fluid supply line to a disinfection connector located on the housing of the PD device or cycler (to which the bypass line is fluidly connected), the bypass line does not enter the disinfection loop until disinfection is performed between PD procedures. Any pathogens that may pass through the filtration membrane of the filtered vent are now killed by the disinfection procedure. The control unit of the system could sequence the valves of the device open as needed to cause the PD fluid pump to draw in filtered air through the filtered vent, for example at the end of the disinfection sequence, to expel the disinfection fluid. Such air could be heated by an in-line heater to help dry the disinfected reusable tubing of the cycler. Alternatively or additionally, the control unit could be used to sequence the valves open as needed to cause the PD fluid pump to push gas formed during disinfection through the filtered vent to the environment (e.g., CO2 if the disinfection fluid contains bicarbonate and is heated).

[0029] In light of the disclosure herein, and without limiting the disclosure in any way, the first aspect of the disclosure can be combined with any other aspect or portion thereof, where the peritoneal dialysis system includes a PD fluid pump, an air trap, a fluid line extending from the air trap, a fluid line valve positioned and arranged to operate with the fluid line, a gas line extending from the top of the air trap, a gas line valve positioned and arranged to operate with the gas line, and a control unit configured to close the fluid line valve, open the gas line valve, and cause the PD fluid pump to pump gas from the air trap into the gas line after patient drain, forming a pocket of gas in the fluid line, and pushing remaining used PD fluid towards the drain line.

[0030] The second aspect of the present disclosure may be combined with any other aspect or portion thereof, wherein the fluid line extends between the air trap and the PD fluid pump.

[0031] The third aspect of the present disclosure may be combined with any other aspect or portion thereof, wherein the gas line is fluidly connected to the fluid line.

[0032] The fourth aspect of the present disclosure may be combined with any other aspect or portion thereof, where the PD system further includes at least one PD fluid line valve disposed upstream of the air trap, the PD fluid pump drawing gas from the air trap, and the control unit further configured to open at least one of the at least one PD fluid line valve while drawing gas from the air trap, such that new PD fluid is pumped into the air trap.

[0033] The fifth aspect of the present disclosure can be combined with any other aspects or portions thereof, where the control unit is further configured to open the fluid line valve, close the gas line valve, and cause the PD fluid pump to pump new PD fluid from the air trap into the fluid line to push the pocket of gas away, and then push the remaining used PD fluid towards the drain line.

[0034] The sixth aspect of the present disclosure may be combined with any other aspect or portion thereof, where the control unit is further configured to cause the PD fluid pump to pump new PD fluid in a manner that maintains the pocket of gas.

[0035] The seventh aspect of the present disclosure may be combined with any other aspect or portion thereof, where the PD system includes a level sensor operable with the air trap, and the control unit is further configured to monitor an output from the level sensor while the PD fluid pump is forming the pocket of gas.

[0036] The eighth aspect of the present disclosure may be combined with any other aspect or portion thereof, wherein the control unit is configured to operate the PD fluid pump such that the pocket of gas has a predetermined volume.

[0037] The ninth aspect of the present disclosure may be combined with any other aspect or portion thereof, where the predetermined volume depends on the amount of gas present in the air trap.

[0038] The tenth aspect of the present disclosure may be combined with any other aspect or portion thereof, wherein the gas present in the air trap comes from a sterilized or disinfected source.

[0039] The eleventh aspect of the present disclosure may be combined with any other aspect or portion thereof, where the PD fluid pump is controlled by the control unit such that the air pocket tends to separate the remaining used PD fluid from the new PD fluid used to advance the air pocket.

[0040] The twelfth aspect of the present disclosure may be combined with any other aspect or portion thereof, where the PD fluid pump is controlled by the control unit in a manner that tends to prevent air pockets from mixing with the remaining used PD fluid and the new PD fluid used to advance the air pockets.

[0041] The thirteenth aspect of the present disclosure may be combined with any other aspect or portion thereof, where the PD fluid pump is controlled by the control unit such that the new PD fluid used to advance the air pocket has a laminar flow.

[0042] A fourteenth aspect of the present disclosure may be combined with any other aspect or portion thereof, where a peritoneal dialysis (PD) system includes a housing, a plurality of PD fluid supply lines extending from the housing, a plurality of disinfection connectors accessible at the housing, a distal end of each supply line being connected to one of the disinfection connectors to perform a disinfection sequence, at least one bypass line extending between at least two of the plurality of disinfection connectors, and a filtered vent positioned in fluid communication with one of the at least one bypass line to allow isolation from a patient during treatment.

[0043] The fifteenth aspect of the present disclosure may be combined with any other aspect or portion thereof, wherein the filtered vent includes a hydrophobic filter membrane.

[0044] The sixteenth aspect of the present disclosure may be combined with any other aspect or portion thereof, where the PD system includes a control unit configured to draw air through a filtered vent, which forces the sanitizing fluid towards a drain line after sanitization.

[0045] The seventeenth aspect of the present disclosure may be combined with any other aspect or portion thereof, wherein the control unit is configured to pneumatically empty the disinfectant fluid from the disinfected lines and components.

[0046] The eighteenth aspect of the present disclosure may be combined with any other aspect or portion thereof, where the control unit is configured such that, as part of a start-up procedure for a subsequent treatment, the disinfected lines and components are emptied, and the disinfected lines and components are further flushed with fresh PD fluid.

[0047] The nineteenth aspect of the present disclosure may be combined with other aspects or portions thereof, where any of the features, functionality, and alternatives described in connection with one or more of Figures 1 to 3 may be combined with any of the features, functionality, and alternatives described in connection with any other of Figures 1 to 3.

[0048] In light of the above aspects and the present disclosure described herein, it is an advantage of the present disclosure to provide a system for an automated peritoneal dialysis ("APD") cycler that helps ensure that the particle load on the system's patient line filter is maintained within the particle loading capacity of the filter.

[0049] Another advantage of the present disclosure is to provide a system for an APD cycler that helps reduce the amount of new PD fluid required for flushing, e.g., flushing spent PD fluid or effluent after patient drainage.

[0050] A further advantage of the present disclosure is that it provides a system for an APD cycler that uses air or other gases (or mixtures thereof) that are naturally available.

[0051] Yet another advantage of the present disclosure is to provide a system for an APD cycler that provides filtered access to the environment that can be used for both intake and exhaust.

[0052] Further features and advantages are described in and will be apparent from the following detailed description and drawings. The features and advantages described herein are not all-inclusive, but many further features and advantages will be apparent to those skilled in the art, particularly in view of the drawings and description. Also, it is not necessary for any particular embodiment to have all the advantages described herein, and it is expressly contemplated that each advantageous embodiment may be separately claimed. Furthermore, it should be noted that the terminology used herein has been selected primarily for purposes of readability and description, and is not intended to limit the scope of the inventive subject matter. [Brief description of the drawings]

[0053] [Figure 1] FIG. 1 is a schematic diagram of one embodiment of an automated peritoneal dialysis ("APD") device or cycler and associated systems of the present disclosure.

[0054] [Diagram 2] FIG. 2 is a cross-sectional elevation view showing one embodiment of a gas pocket of the present disclosure moving through a fluid tube.

[0055] [Diagram 3] FIG. 3 is an elevational view of a filtered vent and vent line for use with the cycler and associated system shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0056] (Detailed Description) Referring now to the drawings, and in particular to FIG. 1, the presently disclosed automated peritoneal dialysis ("APD") system 10 and related techniques include an APD device or cycler 20. The system 10 and cycler 20 seek to eliminate disposable items as much as possible and instead provide a majority of its fluid carrying portions as reusable components, which are disinfected after a treatment. The fluid lines within the device or cycler are reused. In particular, FIG. 1 shows that the cycler 20 includes a housing 22 from which reusable PD fluid supply lines 24a-d extend. FIG. 1 further shows that a reusable patient line 26 also extends from the housing 22 of the device or cycler 20. The reusable patient line 26 is typically longer than the reusable PD fluid supply lines 24a-d and may be wound or rolled within the housing by a spool or hose reel 28 when the reusable patient line 26 is not connected to a patient for a treatment.

[0057] When not connected to a PD fluid container or bag, the reusable PD fluid supply lines 24a-24d and the patient line 26 can be connected to dedicated connectors supported and provided by the housing. The reusable PD fluid lines and the patient line can, for example, extend from the front of the housing and be connected to connectors also provided on the front of the housing for easy access to the PD fluid lines and the patient line. In the illustrated embodiment, the distal ends 24e of the reusable PD fluid supply lines 24a-24d are fluid-tightly and removably attached to disinfection connectors 30a-30d, respectively, provided on the housing 22. The distal end 26d of the reusable patient line 26 is fluid-tightly and removably attached to a patient line connector 32 provided on the housing 22. The disinfection connectors 30a-30d and the patient line connector 32 are configured to automatically close or shut off when the reusable PD fluid supply lines 24a-24d and the reusable patient line 26, respectively, are removed or disconnected from the connectors.

[0058] 1 also shows that the housing 22 is provided with an exhaust line connector 34 that can be removably covered by a movable, e.g., rotatable or slidable, cover 34c. The exhaust line connector 34 receives a disposable exhaust line 36 for the procedure, which may extend to a drain container, or drain bag, or to a house drain. In an alternative embodiment, the exhaust line 36 is reusable and is connected to a disinfection loop as described herein.

[0059] 1 further shows that disposable PD fluid or solution containers or bags 38a-38d are connected to the reusable PD fluid supply lines 24a-24d, respectively. The distal ends 24e of the reusable PD fluid supply lines 24a-24d can be color coded and / or keyed to match the color coded or keyed connectors of the dedicated PD fluid containers or bags 38a-38d. The containers or bags can hold the same or different levels of dextrose or glucose PD fluid, e.g., 1.36% glucose PD fluid, 2.27% glucose PD fluid, and / or the last bag of various formulations of PD fluid, e.g., icodextrin.

[0060] It should be understood that any number of reusable PD fluid lines and PD fluid containers or bags may be provided, including a single reusable PD fluid line and PD fluid container, or two or more reusable PD fluid lines and PD fluid containers. In further alternative embodiments, PD fluid containers or bags 38a-38d are replaced by an on-line PD fluid source connected to and in fluid communication with the single reusable PD fluid line.

[0061] In addition to the disposable drain line 36 (and associated container, if used), and the disposable PD fluid containers or bags 38a-38d, in one embodiment, it is contemplated that the only other disposable component of system 10 is a disposable filter set 40 that is removably connected by the patient at the distal end 26d of the reusable patient line 26 to provide a final stage of PD fluid filtration prior to delivery to the patient. In one embodiment, the disposable filter set 40 is interfaced between the distal end 26d of the reusable patient line 26 and the patient's transfer set, which leads to an indwelling PD catheter inserted into the patient.

[0062] Any one or more, or all, of reusable PD fluid supply lines 24a-d, reusable patient line 26, disinfection connectors 30a-d, patient line connector 32, drain line connector 34, drain line 36, PD fluid containers or bags 38a-d, and patient line filter set 40 may be made of any one or more plastics, such as, for example, polyvinyl chloride ("PVC"), or non-PVC, such as polyethylene ("PE"), polyurethane ("PU"), polypropylene ("PP"), polycarbonate ("PC"), or polyetheretherketone ("PEEK").

[0063] FIG. 1 further illustrates that reusable supply tube 52a extends from each reusable PD fluid supply line 24a-d through PD fluid line valve 54a-d, respectively, to PD fluid in-line heater 56. In one embodiment, each of the valves of APD cycler 20, including PD fluid line valves 54a-d, are electrically actuated valves having a reusable valve body. These valves can block PD fluid flow through the body (e.g., when unpowered for fail-safe operation) or allow PD fluid to flow through the body (e.g., when powered). In the illustrated embodiment, valve 54d is a three-way valve having a normally open port for receiving PD fluid from reusable PD fluid supply line 24b or 24c and a normally closed port for receiving PD fluid from reusable PD fluid supply line 24d. In one embodiment, PD fluid in-line heater 56 is also electrically actuated and is a resistive heater having a reusable heater body that receives PD fluid for, e.g., treatment and disinfection heating. In one embodiment, the in-line heater 56 can heat the PD fluid from room temperature or lower (e.g., if the PD fluid is stored in a cold environment) to body temperature, e.g., 37°C, at a flow rate of at least 200 milliliters ("ml") per minute.

[0064] A first temperature sensor 58a is positioned adjacent to, e.g., downstream of, the heater 56 to provide feedback for temperature control. If desired, a second temperature sensor (not shown) can be provided upstream of the heater 56 so that the incoming temperature of the new PD fluid can be taken into account in the heating algorithm. Immediately downstream of the PD fluid pump 70, a second temperature sensor 58b is shown, which provides, e.g., a second monitoring function that the new PD fluid leaving the PD fluid pump 70 is at the desired temperature for treatment, e.g., body temperature or 37°C.

[0065] In the embodiment shown in FIG. 1, reusable tube 52b extends from the outlet of PD fluid in-line heater 56 to air trap 60. Any of the reusable tubes in the housing of cycler 20, including reusable tubes 52a and 52b, can be made of metal, such as stainless steel, or plastic, such as polyvinyl chloride ("PVC") or non-PVC materials, such as polyethylene ("PE"), polyurethane ("PU"), polypropylene ("PP"), polycarbonate ("PC"), polyetheretherketone ("PEEK"). In one embodiment, one or more level sensors 62a and 62b are positioned adjacent to air trap 60 such that a desired level or desired level range of PD fluid is maintained within air trap 60. In the illustrated embodiment, fluid line valve 54e is positioned downstream of air trap 60 and operates in cooperation with gas line valve 54f, as described herein. If a filtered vent is provided to draw in filtered air, the air trap 60 can be closed upstream by PD fluid line valves 54a-54d to empty the air trap when required by the output of level sensors 62a or 62b.

[0066] Reusable fluid line 52c and gas line 52r extend between fluid line valve 54e and gas line valve 54f, respectively, and PD fluid pump 70, which is disposed within housing 22 of cycler 20. As shown, gas line 52r extends from the top of air trap 60. PD fluid pump 70 includes a reusable pump body that receives (i) PD fluid for treatment and priming, (ii) air for reasons discussed herein, and (iii) a mixture of PD fluid and air, if present at a particular time. That is, pump 70 does not require PD fluid to flow through disposable items such as tubing or cassettes. The reusable pump body of pump 70 receives PD fluid itself. PD fluid pump 70 can be, for example, a piston pump, which is inherently accurate and therefore does not require a separate volumetric measurement device for PD fluid, such as a balance chamber or flow meter. Instead, PD fluid pump 70 can be various types of self-priming, inherently accurate pumps. By controlling the current level to the PD fluid pump, the PD fluid pump 70 can be controlled to pump to or from the patient at or below a pressure limit. The patient's positive pressure limit can be, for example, 1 to 5 psig (e.g., 2 psig (14 kPa)). The patient's negative pressure limit can be, for example, -1.0 psig to -3.0 psig (e.g., -1.3 psig (-9 kPa)). The pump 70 can also provide lower pressures if needed, for example, for an infant or baby. The PD fluid pump 70 is bidirectional and continuous in one embodiment and can be a single pump.

[0067] FIG. 1 further illustrates that, in one embodiment, a fresh PD fluid patient line valve 54g is disposed along the reusable fresh PD fluid patient tube or line 52g between the downstream temperature sensor 58b and the spool or hose reel 28. The fresh PD fluid patient tube or line 52g, in one embodiment, is in fluid communication with the fresh PD fluid lumen of the double lumen reusable patient line 26. The used PD fluid patient line valve 54h, in one embodiment, is disposed along the reusable used PD fluid patient tube or line 52h between the PD fluid pump 70 (via cruciform 64) and the spool or hose reel 28. The used PD fluid patient tube or line 52h, in one embodiment, is in fluid communication with the used PD fluid lumen of the double lumen reusable patient line 26. The exhaust line valve 54i, in one embodiment, is disposed along the reusable exhaust tube or line 52i between the downstream temperature sensor 58b and the exhaust line connector 34.

[0068] A first patient pressure sensor 72a is placed along fresh PD fluid patient tubing or line 52g between the PD fluid pump 70 and the spool or hose reel 28 to measure the positive fluid pressure of the patient PD fluid. A second patient pressure sensor 72b is placed along gas line 52r to measure the pressure of the gas present in air trap 60. A third pressure sensor 72c is placed along reusable disinfectant tubing or line 52d and is positioned to measure the negative pressure of the used PD fluid returning from the patient to the PD fluid pump 70.

[0069] As described above, the patient line connector 32 is disposed in the APD cycler housing 22 to receive the double lumen reusable patient line 26 during disinfection and generally while the patient is not undergoing treatment. In one embodiment, the patient line connector 32 includes a sealed fluid U-turn or 180 degree change that allows disinfection fluid, such as heated PD fluid, to flow from one lumen of the double lumen patient line to the other lumen of the double lumen patient line. The sealed fluid U-turn or 180 degree change can be realized as a cap portion of the reusable patient line connector 32 that can be connected to or detached from the remainder of the patient line connector 32. This includes the double lumen reusable patient line 26 in a disinfection loop.

[0070] As mentioned above, in one embodiment, the drain line 36 is disposable and is connected to the drain line connector 34 that extends from the housing 22 of the APD cycler 20 during treatment. After treatment, the drain line 36 is disconnected and discarded, and the drain line connector 34 is hermetically shut off. The drain line connector 34 also includes a sealed fluid U-turn or 180 degree diversion that allows the sterilizing fluid, e.g., heated PD fluid, to flow from the reusable drain tube or line 52i to one of the multiple reusable sterilizing tubes or lines 52d, or vice versa. The reusable sterilizing tube or line 52d shown in FIG. 1 extends (i) through sterilizing valves 54j and 54k to the reusable used PD fluid patient tube or line 52h, and (ii) through sterilizing valves 54j and 54l to the reusable supply tube 52a. Reusable disinfection tubing or line 52d creates an overall disinfection loop that allows disinfection fluid, e.g., heated PD fluid, to reach all desired disinfection locations: (i) within cycler 20, and (ii) within reusable PD fluid supply lines 24a-24d, as well as within reusable double lumen patient line 26 located outside cycler 20. Disinfection valves 54j, 54k, and 54l are aligned as needed during disinfection to control the flow direction of the disinfection fluid.

[0071] 1 further illustrates that the APD cycler 20 of the system 10 of the present disclosure includes a control unit 100 having one or more processors 102 and one or more memories 104 that receive, store, and process signals or outputs from the pressure sensors 72a-c, temperature sensors 58a and 58b, and possibly a conductivity sensor (not shown). The control unit 100 uses pressure feedback from the pressure sensors 72a and 72b to control the PD fluid pump 70 to pump fresh and used PD at safe patient pressure limits and at safe system limits. The control unit 100 uses temperature feedback from the temperature sensor 58a to control the in-line PD fluid heater 56 to heat fresh PD fluid, for example to body temperature or 37°C.

[0072] The control unit 100, in cooperation with the PD fluid pump 70 and heater 56, opens and closes the PD fluid valves 54a-54l to perform a priming sequence, multiple patient fill sequences, multiple patient drain sequences, and a disinfection sequence after a PD procedure. In the disinfection sequence, each of the reusable PD fluid supply lines 24a-24d is connected to a corresponding disinfection connector 30a-30d, the reusable patient line 26 is connected to the reusable patient line connector 32, and the drain line connector 34 is covered or capped by its integral cover 34. The disinfection sequence prepares the APD cycler 20 for the next procedure. In one embodiment, after the final drain, the remaining fresh PD fluid is heated and used as the disinfection fluid for disinfection.

[0073] The control unit 100 shown in FIG. 1 also includes a video controller 106 that interacts with a user interface 108. The video controller 106 may include a display screen operated by one or more electromechanical buttons, such as a touch screen and / or a membrane switch. The user interface 108 may also include one or more speakers for outputting alerts, warnings, and / or voice guidance commands. The user interface 108 may be included with the cycler 20 as shown in FIG. 1 and / or may be a remote user interface operated by the control unit 100. The control unit 100 may also include a transceiver (not shown) that functions in conjunction with a physician or clinician's computer to transmit treatment data to and receive prescription instructions from a physician or clinician's server, and a wired or wireless connection to a network, e.g., the Internet.

[0074] In one embodiment, after the patient drain is complete, the control unit 100 opens the gas line valve 54f and closes the fluid line valve 54e, causing the PD fluid pump 70 to draw a small amount (e.g., 0.5 ml) of air or gas (or mixture) present at the top of the air trap 60 from the top of the air trap 60. The PD fluid pump 70 can operate in one or more pumping strokes to draw the desired volume of gas. The control unit 100 also opens the exhaust line valve 54i, causing the PD fluid pump 70 to push air bubbles through the reusable fluid line 52c toward the exhaust line connector 34. The moving air bubbles push any residual drainage or drain fluid from the previous patient drain toward the exhaust line connector 34 and into the house or container drain.

[0075] To increase the effluent or residual effluent fluid, the control unit 100 may operate the PD fluid pump 70 with the gas line valve 54f open and the fluid line valve 54e closed to create an array of small volume air pockets (e.g., 0.5 ml) each of which pushes a volume of effluent or residual effluent fluid toward effluent. Alternatively, the control unit 100 may operate the PD fluid pump 70 with the gas line valve 54f open and the fluid line valve 54e closed to draw larger volume air pockets (e.g., 5-10 ml) into and out of the air trap 60, thereby pushing a larger volume of residual effluent or used PD fluid toward effluent. In one embodiment, the amount of air or gas drawn and used to form the one or more air pockets depends on the amount of air or gas available in the air trap 60. Regardless of the volume of the one or more air pockets, a goal of the system 10 of the present disclosure is to reduce the amount of mixing of new and used PD fluid. This reduces the amount of fresh PD fluid required to flush reusable lines, such as the portion of line 52c that carries used PD fluid to drain and drain line 52i. In certain types of APDs, particularly tidal flow APDs, that have many patient fills and drains, the amount of fresh PD fluid required for flushing can build up to a significant value. The air pocket(s) act as a barrier(s) between the new and used PD fluid, limiting mixing of the PD fluids.

[0076] In any of the above air removal and air pocket formation embodiments, it is contemplated that the control unit 100 opens one or more PD fluid line valves 54a-54d to allow a similar volume of new PD fluid to enter the air trap 60 while the air pocket(s) are being removed from the air trap to avoid creating a negative pressure in the air trap. In any of the above air removal and air pocket formation embodiments, it is contemplated that the control unit 100 also monitors the output from the upper level sensor 62a to ensure that new PD fluid is not drawn from the air trap 60 into the gas line 52r. If no air is detected (fluid is detected) at the upper level sensor 62a while the air pocket formation is in progress, the control unit 100 in one embodiment closes the gas line valve 54f, opens the fluid line valve 54e, and causes the PD fluid pump 70 to perform a flush using new PD fluid instead. In an alternative embodiment, the control unit 100 is programmed to attempt to draw air from the top of the air trap 60 regardless of the value read by the upper level sensor 62a (this can be done whether before or after the gas line valve 54f is opened).

[0077] It should be appreciated that air pockets can be used in addition to exhaust line 36 to flush alternative or additional fluid lines. In system 10, for example, air pockets can be used to flush patient line 26, PD fluid supply lines 24a-24d, and / or line 52d. Control unit 100 can be configured to open one or more valves 54a-54l to direct the air pocket(s) to the desired patient line 26, PD fluid supply line 24a-24d, and / or line 52d.

[0078] 2, after one or more air pockets are formed and introduced, the control unit 100 closes the gas line valve 54f, opens the fluid line valve 54e, and opens one or more PD fluid line valves 54a-54d (if not already open). This causes the PD fluid pump 70 to push one or more gas pockets 68 toward the drain line connector 34, thereby pushing residual effluent or used PD fluid toward the drain line 36 and into the house or container drain. The key line for removing residual used PD fluid or effluent is the reusable fluid line 52c, located between the cross section 64 upstream of the PD fluid pump 70 and the T-shaped section 66 downstream of the PD fluid pump 70. FIG. 2 shows the gas pockets 68 (e.g., air, CO2, or mixtures thereof) at different times flowing along a line, such as the reusable fluid line 52c, the reusable drain tube or line 52i, or the flexible, e.g., disposable, drain line 36. In the illustrated embodiment, the new PD fluid is located upstream of the gas pocket 68 , while the remaining used PD fluid or effluent is located downstream of the gas pocket 68 .

[0079] To create a laminar fluid flow that is less likely to impede the formation of the gas pocket 68, the control unit 100 may cause the PD fluid pump to pump new PD fluid that pushes the gas pocket 68 at a slower rate, for example 100 ml / min or less. The pump speed in one embodiment may be selected to create a Reynolds number of less than 2300 to keep the fluid flow in the laminar region. If the PD fluid pump 70 is further operated at 200 ml / min and the associated reusable tubing is assumed to have an inner diameter of 2 mm, a Reynolds number of about 950 is obtained, which is well below the laminar range of 2300 (the tubing diameter may be larger, for example 4 mm inner diameter, and still remain laminar at a flow rate of 200 ml / min). However, FIG. 1 shows that the reusable tubing includes multiple component connections, transitions, etc. that tend to make the PD fluid flow more turbulent. However, for example, operating the PD fluid pump 70 at a flow rate of 50-100 ml / min to perform the air pocket flushing described herein will result in a highly laminar PD fluid flow.

[0080] Referring now to Figure 3, an alternative embodiment of the system 10 of the present disclosure is shown. It should be understood that the system 10 of Figure 1 is closed to the environment, meaning that the gas collected at the top of the air trap 60 comes from a sterilized site, perhaps from the PD fluid containers or bags 38a-38d, or perhaps as a by-product of disinfection (e.g., CO2 if the disinfectant fluid contains bicarbonate and is heated). Thus, the gas in the embodiment of Figure 1 or Figure 2 is safe in the sense that it should not promote microbial growth.

[0081] In FIG. 3, a filtered vent 74 is contemplated to be added to the end of the vent line 52v. This allows air to be drawn in from the environment and unwanted gases (e.g., CO2, air, or a mixture thereof) to be exhausted to the environment. The filtered vent 74 in one embodiment includes a hydrophobic filter membrane, e.g., 0.2 microns, configured to provide sterile filtering of the environmental air entering through the filtered vent 74. A one-way valve or check valve 76 can be placed in the vent line 52v to prevent PD fluid from reaching the filtered vent 74. A solenoid vent valve 78 under the control of the control unit 100 can also be placed along the vent line 52v to selectively allow filtered air into the system 10. If the filtered vent 74 is connected to a fluid line, the valve 78 can include a three-way valve to allow selective access to air. In one embodiment, the three-way valve 78 is connected along the fluid line between the air trap 60 and the gas line valve 54f.

[0082] The filter membrane associated with the disposable filter set 40 is also a sterilizing grade hydrophilic membrane. It is placed in the reusable patient line 26 in communication with the patient, but is discarded and replaced after each treatment. The filtered vent 74, on the other hand, is used over multiple treatments, but is replaced, for example, between services, since it poses a higher risk of microorganisms than the filter membrane associated with the disposable filter set 40. It is therefore conceivable to have the vent line 52v leading to the filtered vent 74 in communication with a fluid location in the system 10 that is not part of the patient circuit during treatment, either for patient fill or patient drain. The system 10 in FIG. 1 shows several locations to which the vent 74 can be connected. For example, the vent 74 can be connected via the vent line 52v to the bypass line 52y extending between the disinfection connectors 30a and 30b, as well as to the bypass line 52z extending between the disinfection connectors 30c and 30d, respectively. The bypass lines 52y or 52z as shown in FIG. 1 are isolated during treatment and are not in fluid communication with the patient.

[0083] The distal ends 24e of the reusable PD fluid supply lines 24a-d are fluidly connected to the disinfection connectors 30a-d such that the bypass lines 52y or 52z are not placed in the disinfection loop until disinfection between PD treatments occurs, where any pathogens that may pass through the filtration membrane of the filtered vent 74 are killed by the disinfection procedure.

[0084] In another embodiment, the filtered vent 74 is placed in fluid communication with one of the disinfection connectors 30a-30d or with one of the PD fluid supply lines 24a-24d. In some cases, the filtered vent 74 is placed in fluid communication with the reusable supply tube 52a or the PD fluid pump 70.

[0085] In further embodiments, a filtered vent 74 via vent line 52v can be connected to air trap 60. If system 10 is not configured to receive sterilized gas, filtered vent 74 can be used to draw outside air into system 10. In these embodiments, filtered vent 74 is fluidly coupled to the top of air trap 60 or is integrally formed with air trap 60.

[0086] It is contemplated that the control unit 100 of the system 10 may sequence valves open as needed to cause the PD fluid pump 70 to draw in filtered air through the filtered vent 74, for example at the end of a disinfection sequence, to expel disinfectant fluid. Such air may be heated by the in-line heater 56 to help dry the disinfected reusable tubing of the cycler 20 and the system 10. Alternatively, or in addition, the control unit 100 may be used to sequence valves open as needed to cause the PD fluid pump 70 to push gases formed during disinfection through the filtered vent 74 to the environment (e.g., CO2 if the disinfectant fluid contains bicarbonate and is heated).

[0087] As mentioned above, it is contemplated that the air trap 60 may be provided with a filtered vent (also with a one-way valve 76 and a solenoid valve 78 under the control of the control unit 100). Here, the filtered vent 74 is in valving fluid communication with the air trap 60 used during the procedure, so that the control unit 100 may drain the reusable fluid lines and components of the PD device or cycler 20 of the system 10 after disinfection at the end of the procedure or at the beginning of the start-up procedure of a new procedure. This is also the case for the filtered vent 74 connected to the bypass lines 52y and 52z. Thus, any unintended bacteria or pathogens drawn into the reusable lines (e.g., due to a damaged filter at the vent 74) are flushed out. At the end of the procedure, such draining is preferably performed to remove the bacteria or pathogens as soon as possible. At the beginning of a new procedure, such draining may be performed to further flush the bacteria or pathogens with fresh, new PD fluid.

[0088] It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art, and it is therefore intended that such changes and modifications be covered by the appended claims.

Claims

1. 1. A peritoneal dialysis ("PD") system comprising: a PD fluid pump; an air trap; a fluid line extending from the air trap; a fluid line valve positioned and arranged to operate with said fluid line; a gas line extending from the top of the air trap; a gas line valve positioned and arranged to operate with said gas line; a control unit configured to close the fluid line valve, open the gas line valve, and cause the PD fluid pump to pump gas from the air trap into the gas line after patient drain, forming a pocket of gas in the fluid line and forcing any remaining spent PD fluid toward a drain line; A PD system comprising:

2. The PD system of claim 1 , wherein the fluid line extends between the air trap and the PD fluid pump.

3. The PD system of claim 1 or 2, wherein the gas line is fluidly connected to the fluid line.

4. 3. The PD system of claim 1, further comprising at least one PD fluid line valve disposed upstream of the air trap, wherein the PD fluid pump draws gas from the air trap, and the control unit is further configured to open at least one of the at least one PD fluid line valve such that new PD fluid is pumped into the air trap while gas is being drawn from the air trap.

5. 3. The PD system of claim 1 or 2, wherein the control unit is further configured to open the fluid line valve, close the gas line valve, and cause the PD fluid pump to pump new PD fluid from the air trap into the fluid line, pushing the pocket of gas out, and then pushing the remaining spent PD fluid towards the exhaust line.

6. The PD system of claim 5 , wherein the control unit is further configured to cause the PD fluid pump to pump the new PD fluid in a manner that maintains the pocket of gas.

7. 10. The PD system of claim 1, further comprising a level sensor operable with the air trap, the control unit further configured to monitor an output from the level sensor while the PD fluid pump is forming the pocket of gas.

8. The PD system of claim 1 , wherein the control unit is configured to operate the PD fluid pump such that the pocket of gas has a predetermined volume.

9. The PD system of claim 8 , wherein the predetermined volume is dependent on the amount of gas present in the air trap.

10. 9. The PD system of claim 1, 7, or 8, wherein the gas present in the air trap comes from a sterilized or disinfected source.

11. 9. The PD system of claim 1, 7, or 8, wherein the PD fluid pump is controlled by the control unit such that the air pocket tends to separate the remaining used PD fluid from new PD fluid used to advance the air pocket.

12. 10. The PD system of claim 1, wherein the PD fluid pump is controlled by the control unit such that the air pocket tends to prevent the remaining spent PD fluid from mixing with new PD fluid used to advance the air pocket.

13. 10. The PD system of claim 1, wherein the PD fluid pump is controlled by the control unit such that fresh PD fluid used to advance the air pocket has a laminar flow.

14. The PD system of claim 1 , wherein the pocket of gas in the fluid line comprises a series of pockets of gas in the fluid line.

15. 1. A peritoneal dialysis ("PD") system comprising: Housing and a plurality of PD fluid supply lines extending from the housing; a plurality of disinfection connectors accessible at the housing, wherein a distal end of each of the supply lines is connected to one of the disinfection connectors to perform a disinfection sequence; a filtered vent positioned in fluid communication with one of the disinfection connectors or one of the plurality of PD fluid supply lines; A PD system comprising:

16. further comprising at least one bypass line extending between at least two of the plurality of disinfection connectors; 16. The PD system of claim 15, wherein the filtered vent is placed in fluid communication with one of the at least one bypass line such that the filtered vent is isolated from the patient during treatment.

17. 17. The PD system of claim 15 or 16, wherein the filtered vent includes a hydrophobic filter membrane.

18. 17. The PD system of claim 15 or 16, further comprising a control unit configured to draw air through the filtered vent, the air forcing disinfectant fluid towards an exhaust line after disinfection.

19. 20. The PD system of claim 18, wherein the control unit is further configured to empty disinfectant fluid from disinfected lines and components with the air.

20. 20. The PD system of claim 19, wherein the control unit is further configured to empty the disinfected lines and components as part of a start-up procedure for a subsequent treatment.

21. 21. The PD system of claim 20, wherein the control unit is further configured to cause the disinfected lines and components to be flushed with new PD fluid.

22. 20. The PD system of claim 18, wherein the control unit is further configured to cause disinfectant fluid to be provided from at least one fluid container via at least one of the plurality of PD fluid supply lines using a PD fluid pump.

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