Peritoneal dialysis system with disinfection gas release

Abstract

A peritoneal dialysis (「PD」) system includes a PD fluid pump, a disinfection loop including the PD fluid pump and containing PD fluid used to disinfect the disinfection loop, and an acidic solution source positioned and arranged to supply an acidic solution to the disinfection loop during disinfection using the PD fluid. The disinfection loop includes an air trap and a pressure sensor positioned and arranged to sense PD fluid pressure during disinfection, the pressure sensor outputs to a control unit, and the control unit is configured to open at least one gas valve positioned along at least one gas line leading to the upper part of the air trap when the PD fluid pressure reaches or exceeds a threshold PD fluid pressure due to gas formation caused by mixing the acidic solution with the PD fluid.

Description

Background Art

[0001] Priority Claim and Cross - Reference to Related Applications This application claims the priority and benefit of U.S. Provisional Patent Application No. 63 / 354,523, filed on June 22, 2022, entitled "PERITONEAL DIALYSIS SYSTEM HAVING DISINFECTION GAS RELIEF", the entire content of which is incorporated herein by reference and relied upon.

[0002] Background The present disclosure generally relates to medical fluid treatment, and more particularly to dialysis fluid treatment.

[0003] For various reasons, a person's renal system can cease to function. Renal failure causes several physiological impairments. It becomes impossible to balance water and minerals or excrete the daily metabolic load. Toxic end - products of metabolism, such as urea, creatinine, uric acid, etc., may accumulate in the patient's blood and tissues.

[0004] Reduced kidney function, especially renal failure, is treated by dialysis. Dialysis removes waste products, toxins, and excess water from the body that a normally functioning kidney would normally remove. Dialysis treatment for renal function replacement is extremely important for many people because this treatment is life - critical.

[0005] One type of renal failure therapy is hemodialysis ("HD"), which generally uses diffusion to remove waste products from a patient's blood. A diffusion gradient is created across a semi - permeable dialyzer between the blood and an electrolyte solution called dialysate or dialysis fluid, which causes diffusion.

[0006] Hemofiltration (HF) is an alternative renal replacement therapy that convectively transports toxins from a patient's blood. HF is achieved by adding a replacement fluid or substitution fluid to the extracorporeal circuit during the procedure. The replacement fluid, and the fluid accumulated in the patient during the procedure, are ultrafiltered during the HF procedure, resulting in a convective transport mechanism that is particularly beneficial for the removal of medium and large molecules.

[0007] Hemodiafiltration ("HDF") is a treatment modality that combines convective clearance and diffusive clearance. HDF provides diffusive clearance using a dialysate fluid that flows through a dialyzer, similar to standard hemodialysis. Additionally, a replacement solution is provided directly to the extracorporeal circuit to provide convective clearance.

[0008] Most HD, HF, and HDF treatments are performed in a facility. Currently, there is a trend towards home hemodialysis ("HHD"), in part because HHD can be performed daily and typically offers therapeutic benefits superior to 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. Patients receiving more frequent treatments do not experience the same degree of downcycle (fluid and toxin fluctuations) as in-facility patients who accumulate two or three days' worth of toxins prior to treatment. In certain regions, the nearest dialysis facility may be miles from a patient's home, consuming most of a day in door-to-door treatment time. Treatments at a facility close to a patient's home can also consume most of a patient's day. HHD can be performed at night or during the day when the patient is relaxed, working, or otherwise productive.

[0009] Another type of kidney failure treatment is peritoneal dialysis ("PD"), which involves injecting a dialysis solution, also called dialysis fluid, into the patient's peritoneal cavity through a catheter. 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 across the membrane is created. Osmotic substances in the PD dialysis fluid create 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, for example, multiple times.

[0010] There are various types of peritoneal dialysis therapies, including continuous ambulatory peritoneal dialysis ("CAPD"), automated peritoneal dialysis ("APD"), tidal flow dialysis, and continuous flow peritoneal dialysis ("CFPD"). CAPD is a manual dialysis procedure. Here, the patient manually connects the implanted catheter to the drain so that the used or spent dialysis fluid can be drained from the peritoneal cavity. The patient then switches the fluid connection so that the patient catheter communicates with a bag of unused dialysis fluid and injects the unused dialysis fluid into the patient through the catheter. The patient disconnects the catheter from the bag of unused dialysis fluid so that the dialysis fluid can remain in the peritoneal cavity, whereupon the transfer of waste products, toxins, and excess water occurs. 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 great improvement.

[0011] Automated peritoneal dialysis (「APD」) is similar to CAPD in that the dialysis procedure involves cycles of drainage, fill, and dwell. However, the PD machine typically performs these cycles automatically while the patient is sleeping. The PD machine liberates the patient from having to perform the treatment cycles manually and from having to transport supplies during the day. The PD machine is fluidly connected 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 dialysis fluid source through the catheter into the patient's peritoneal cavity. The PD machine also allows the dialysis fluid to dwell within the cavity and enables the transfer of waste products, toxins, and excess water. The source may contain several liters of dialysis fluid in multiple solution bags.

[0012] The PD machine pumps used or spent dialysis fluid out of the patient's abdominal cavity through the catheter for drainage. Similar to the manual process, several drainage cycles, fill cycles, and dwell cycles are performed during dialysis. The "last fill" may be performed at the end of the PD treatment. The last fill fluid may remain in the patient's peritoneal cavity until the start of the next treatment or may be emptied manually at some point during the day.

[0013] In any of the above modalities that use an automated machine, the automated machine typically operates using a disposable set that is 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, daily disposables require storage space and can be cumbersome for homes and businesses. Furthermore, daily disposable exchanges require daily setup time and effort by the patient or caregiver at home or in a clinic.

[0014] For each of the above reasons, it is desirable to provide a PD machine that reduces disposable waste. By doing so, such deposits can be prevented by the introduction of an acidic solution to the extent that calcium carbonate deposits are generated by disinfection. The product gas resulting from the introduction of the acidic solution can be released into the disinfected tubes of the PD machine. Therefore, a method for releasing such gas is needed. SUMMARY OF THE INVENTION MEANS FOR SOLVING THE PROBLEM

[0015] Overview Known automated peritoneal dialysis (「PD」) systems typically include a machine or cycler that accepts and operates a pumping cassette having a rigid portion and a deformable soft portion for performing pumping and valve operations. The rigid portion is attached to tubes that extend to various bags. For home patients, loading the disposable cassette and its associated tubes and bags for treatment can be cumbersome. The total amount of disposable items can lead to multiple setup procedures that require patient input, which can also leave room for error.

[0016] On the other hand, the PD systems and related techniques of the present disclosure convert many of the fluid conveyance parts of the PD system into reusable parts, which are disinfected after treatment. The fluid lines within the machine or cycler are reused. Other disposable items can include a drain line leading to a drain bag or house drain, and one or more PD fluid containers or bags, such as PD fluid containers with various glucose or dextrose levels, and, for example, a final bag container containing icodextrin. In one embodiment, a disposable filter is installed at the distal end of the patient line to provide the final stage of PD fluid filtration before delivery to the patient.

[0017] The PD system of the present disclosure includes a PD cycler having 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 line can be connected to a disinfected connector provided and supported by the housing. The reusable PD fluid line can also extend, for example, from the front of the housing and be connected to a disinfected connector provided at the front of the housing for immediate access to the PD fluid line. The reusable PD fluid line may be color-coded and / or keyed to match a colored connector or keyed connector of the PD fluid container or bag. The container or bag can hold PD fluid at various glucose or glucose levels, such as final bags of various formulations of PD fluid including 1.36% glucose PD fluid, 2.27% glucose PD fluid, and / or PD fluid such as icodextrin. The PD fluid may contain a bicarbonate component.

[0018] Inside the housing, the reusable tube extends from each of the reusable PD fluid lines through a PD fluid supply valve for each PD fluid line to a PD fluid in-line heater. In one embodiment, each valve of the PD cycler is an electrically actuated valve having a reusable valve body that blocks the PD fluid (e.g., when de-energized) or allows the PD fluid to flow through the valve body (e.g., when energized). In one embodiment, the PD fluid in-line heater is also electrically actuated and is, for example, a resistance heater having a reusable heater body that receives the PD fluid for heating. The in-line heater in one embodiment can heat the PD fluid from room temperature to body temperature, such as 37°C, at a flow rate of at least 200 milliliters (ml) / minute. A temperature sensor is positioned adjacent to the heater, for example, downstream of the heater, to provide feedback for temperature control.

[0019] In one embodiment, a reusable tube extends from the outlet of the PD fluid in-line heater to the air trap. Any of the tubes within the cycler housing may be made of metal, such as stainless steel, or plastic, such as polyvinyl chloride (“PVC”), or a non-PVC material such as polyethylene (“PE”), polyurethane (“PU”), polyetheretherketone (“PEEK”), or polycarbonate (“PC”). In one embodiment, one or more level sensors are positioned adjacent to the air trap such that a desired liquid level, or a desired range of liquid levels, of the PD fluid is maintained within the air trap. The fluid line valve is positioned along a reusable fluid line downstream of the air trap in one embodiment. As described herein, at least one gas line valve is provided and used that is positioned along at least one gas line. The air trap may be closed upstream by a PD fluid supply valve to drain the air trap when indicated by the output of the level sensor.

[0020] The reusable PD fluid pump is positioned within the cycler housing and includes a reusable pump body that receives PD fluid for pumping. That is, this pump does not require PD fluid to flow within a disposable article such as a tube or cassette. The PD fluid pump may be an electric piston pump, and since this piston pump is inherently accurate, a separate PD fluid metering device, such as a balance chamber or a device using the ideal gas law, is not required. Alternatively, the PD fluid pump may be an electric gear pump or a centrifugal pump that may operate with a separate PD fluid metering device.

[0021] By controlling the current level to the PD fluid pump, the PD fluid pump can be controlled to pump between the patient below the pressure limit. The positive pressure limit of the patient can be, for example, 1 to 5 psig (e.g., 2 psig (14 kPa)). The negative pressure limit of the patient 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, whereby a single pump may be provided.

[0022] The PD cycler of the PD system of the present disclosure includes a control unit having one or more processors and one or more memories that receive signals or outputs from a pressure sensor, a temperature sensor, and optionally a conductivity sensor and process the signals or outputs as feedback. The control unit uses pressure feedback to control the PD fluid pump to operate within a safe patient pressure limit during treatment and within a safe system limit during disinfection. The control unit uses temperature feedback to control the PD fluid heater to heat unused PD fluid, for example, to body temperature.

[0023] Also, the control unit opens and closes the PD fluid valve in combination with the PD fluid pump and heater to operate a priming sequence, a patient filling sequence, a patient discharge sequence, and a post-PD treatment disinfection sequence. Each of at least one reusable PD fluid supply line is connected to one of at least one disinfection connector, and the reusable patient line is connected to a reusable patient line connector. The disinfection sequence prepares the PD cycler for the next treatment. In one embodiment, unused PD fluid that is not being used is heated after final discharge and used for disinfection.

[0024] If unused PD fluid is used as the disinfection fluid, calcium carbonate is likely to form in the disinfected flow path and the flow components of the PD machine or cycler if it contains bicarbonate. Therefore, the system includes a source of acidic solution used during disinfection to prevent the formation of calcium carbonate. The acidic solution may be, for example, a citric acid solution, such as 50% citric acid. An acidic solution valve is positioned between the acidic solution source and the disinfected flow path and flow components of the PD machine or cycler. In one embodiment, the control unit operates the PD fluid pump at a specific flow rate and pressure, opens the acidic solution valve for a specific time to meter a desired amount of citric acid solution into the disinfected flow path and flow components of the PD machine or cycler, and the determined time can be determined and tested empirically. In an alternative embodiment, the PD machine or cycler includes a temperature-compensated conductivity cell, for example, used to provide feedback such that the acidic solution valve is opened until a desired conductivity is reached. In other alternative embodiments, a small, for example, essentially accurate acidic solution metering pump is provided under the control of the control unit to meter a desired amount of acidic solution into the disinfection loop of the PD machine or cycler.

[0025] When the PD solution used for disinfection contains a bicarbonate component, the acidic solution causes the bicarbonate to release carbon dioxide (“CO2”) gas into the disinfection loop. In a closed system, the released CO2 gas can increase the pressure within the disinfection loop, which may affect the reliability of certain disinfected components. To prevent the pressure increase from reaching a point where it can affect the component reliability, it is contemplated that the control unit monitors the pressure within the disinfection loop during disinfection using the output from one or more pressure sensors. When the pressure reaches a specific threshold above the disinfection operating pressure (e.g., 10 kPa (1.5 psig)), the control unit first checks to confirm that the disinfection fluid (e.g., PD fluid mixed with the acidic solution) is below the upper threshold or level sensor within the air trap of the PD machine. If so, the control unit in one embodiment opens at least one gas or vent valve positioned along at least one gas or vent line. At least one gas line in one embodiment communicates with the drain line connector. The pressurized CO2 gas can then vent to and from the drain line connector via at least one gas line, for example, via a flexible drain line that communicates from the drain line connector to a house drain (e.g., toilet or bathtub) or a drain container.

[0026] In an alternative embodiment for removing the CO2 gas to be discharged, one or more PD fluid pumps are used to pump the CO2 gas into the drain line. The PD fluid pump may be, for example, a PD fluid pump used during the procedure to draw effluent from the patient and push out the effluent to be discharged.

[0027] In an alternative embodiment, after the control unit confirms that the disinfection fluid (e.g., a PD fluid mixed with an acidic solution) is below an upper threshold or level sensor within the air trap of the PD machine, the control unit opens a valve leading to a container of a scale remover, such as citric acid, so that pressurized CO2 gas can flow into the container. The container may be flexible and expandable to receive the CO2 gas, or it may be rigid but large to receive the CO2 gas. A priming sensor may be provided along a tube or line leading to the container of the scale remover to allow CO2 gas, rather than the PD fluid, to flow into the container. The opening of the valve to allow CO2 gas to flow into the scale remover fluid container may be performed multiple times as needed over the course of the PD treatment. The CO2 gas may be retained within the container until the next treatment, at which point it is pumped out to be discharged during the priming sequence using the PD fluid.

[0028] In a first aspect of the disclosure, which is in no way limiting of the disclosure but may be used in conjunction with any other aspect or portion thereof, a peritoneal dialysis ("PD") system includes a PD fluid pump, a disinfection loop including the PD fluid pump and configured to allow the use of the PD fluid to disinfect the disinfection loop, an air trap located along the disinfection loop, at least one gas valve located along at least one gas line leading to the upper portion of the air trap, a pressure sensor positioned and arranged to sense the PD fluid pressure within the disinfection loop during a disinfection sequence, and a control unit configured such that the pressure sensor outputs to the control unit and the control unit is configured to open at least one gas valve when the PD fluid pressure within the disinfection loop reaches or exceeds a threshold PD fluid pressure due to gas formation caused during the disinfection sequence.

[0029] In a second aspect of the disclosure, which is in no way limiting of the disclosure but may be used in conjunction with any other aspect or portion thereof, gas formation is caused by mixing the PD fluid with an acidic solution.

[0030] In a third aspect of the disclosure, which may be used in conjunction with any other aspect or portion thereof, the control unit is configured to check that the PD fluid level in the air trap is not too high before opening at least one gas valve.

[0031] In a fourth aspect of the disclosure, which may be used in conjunction with any other aspect or portion thereof, the PD system includes a discharge line for discharging used PD fluid during a procedure, and by opening at least one gas valve, the PD fluid pressure caused by gas formation can dissipate towards the discharge line.

[0032] In a fifth aspect of the disclosure, which may be used in conjunction with any other aspect or portion thereof, the control unit is further configured to perform at least one of (i) closing at least one PD fluid valve located adjacent to the air trap, or (ii) stopping the PD fluid pump when the PD fluid pressure reaches or exceeds a threshold PD fluid pressure.

[0033] In a sixth aspect of the disclosure, which may be used in conjunction with any other aspect or portion thereof, the pressure sensor is positioned along one of at least one gas line in fluid communication with the disinfection loop such that the pressure sensor can sense the PD fluid pressure during the disinfection sequence.

[0034] In a seventh aspect of the disclosure, which may be used in conjunction with any other aspect or portion thereof, the pressure sensor or a second pressure sensor that outputs to the control unit senses the dissipation of the PD fluid pressure after opening at least one gas valve, and the control unit is further configured to close at least one gas valve and continue the disinfection sequence upon receiving an output indicating the dissipation of the PD fluid pressure.

[0035] In an eighth aspect of the disclosure, which may be used with any other aspect or portion thereof, the PD fluid system is configured such that upon opening of at least one gas valve, gas can dissipate from the top of the air trap through one of at least one gas line toward the drain.

[0036] In a ninth aspect of the disclosure, which may be used with any other aspect or portion thereof, the control unit is further configured to open or keep open at least one gas valve based on one or more of (i) the amount of gas, (ii) the duration since the start of gas formation, and / or (iii) the number of times the control unit has previously opened at least one gas valve.

[0037] In a tenth aspect of the disclosure, which may be used with any other aspect or portion thereof, a peritoneal dialysis (「PD」) system includes a PD fluid pump, a disinfection loop including the PD fluid pump and enabling use of PD fluid to disinfect the disinfection loop, an acidic solution source containing an acid for use during a disinfection sequence, a drain line positioned and arranged to discharge used PD fluid during a treatment, a gas line, at least one gas valve positioned along the gas line and enabling fluid communication between the gas line and the drain line, a pressure sensor positioned and arranged to sense the PD fluid pressure within the disinfection loop during the disinfection sequence, and a control unit. The pressure sensor outputs to the control unit, and the control unit is configured to open at least one gas valve when the PD fluid pressure within the disinfection loop reaches or exceeds a threshold PD fluid pressure due to gas formed by mixing PD fluid and acid during the disinfection sequence, such that by opening at least one gas valve, the PD fluid pressure due to gas formation can dissipate toward the drain line.

[0038] In an eleventh aspect of the disclosure, which may be used in conjunction with any other aspect or portion thereof, the PD system includes a heater configured to heat the PD fluid and acid to a disinfection temperature during a disinfection sequence.

[0039] In a twelfth aspect of the disclosure, which may be used in conjunction with any other aspect or portion thereof, the PD fluid includes bicarbonate and the gas formed is carbon dioxide (“CO2”) gas.

[0040] In a thirteenth aspect of the disclosure, which may be used in conjunction with any other aspect or portion thereof, the control unit is further configured to open or keep open at least one gas valve based on one or more of (i) the amount of gas, (ii) the duration from the start of gas formation, and / or (iii) the number of times the control unit has previously opened at least one gas valve.

[0041] In a fourteenth aspect of the disclosure, which may be used in conjunction with any other aspect or portion thereof, a peritoneal dialysis (“PD”) system includes a PD fluid pump, a disinfection loop including the PD fluid pump, the disinfection loop being configured such that the PD fluid can be used to disinfect the disinfection loop, an air trap positioned along the disinfection loop, at least one gas valve positioned along at least one gas line leading to the top of the air trap, a pressure sensor positioned and arranged to sense the PD fluid pressure within the disinfection loop during a disinfection sequence, and a control unit, the pressure sensor outputting to the control unit, the control unit being configured to open at least one gas valve to pump a predetermined amount of gas from the air trap to the PD fluid pump when the PD fluid pressure within the disinfection loop reaches or exceeds a threshold PD fluid pressure due to gas formation caused during the disinfection sequence.

[0042] In a 15th aspect of the present disclosure that may be used with any other aspect or a part thereof, the PD system includes a patient line valve positioned along the patient line, and the control unit opens the patient line valve when the PD fluid pump pumps a predetermined amount of gas from the air trap.

[0043] In a 16th aspect of the present disclosure that may be used with any other aspect or a part thereof, the PD system includes a drain line valve positioned along the drain line, and the control unit closes the patient line valve and opens the drain line valve after the PD fluid pump pumps a predetermined amount of gas from the air trap and delivers the gas to the drain line.

[0044] In a 17th aspect of the present disclosure that may be used with any other aspect or a part thereof, a peritoneal dialysis ("PD") system includes a PD fluid pump, a disinfection loop including the PD fluid pump, the disinfection loop being enabled to use PD fluid to disinfect the disinfection loop, an acidic solution source containing an acid for use during a disinfection sequence, a line positioned and arranged to deliver the acid to the disinfection loop, at least one valve positioned along the line to enable fluid communication between the line and the disinfection loop, a pressure sensor positioned and arranged to sense the PD fluid pressure within the disinfection loop during the disinfection sequence, and a control unit configured such that when the pressure sensor outputs to the control unit and the PD fluid pressure within the disinfection loop reaches or exceeds a threshold PD fluid pressure due to gas formed by mixing the PD fluid and the acid during the disinfection sequence, the control unit opens at least one gas valve, and by opening the at least one gas valve, the PD fluid pressure caused by gas formation can dissipate towards the drain line.

[0045] In an 18th aspect of the present disclosure that may be used with any other aspect or a part thereof, the line extends from the acidic solution source to an air trap positioned along the disinfection loop.

[0046] In a 19th aspect of the disclosure that may be used with any other aspect or portion thereof, the control unit is configured to open at least one gas valve when the PD fluid pressure in the disinfection loop reaches or exceeds a threshold PD fluid pressure and the upper level sensor in the air trap does not detect PD fluid.

[0047] In a 20th aspect of the disclosure that may be used with any other aspect or portion thereof, the threshold PD fluid pressure is above the operating pressure used for the disinfection sequence.

[0048] In a 21st aspect of the disclosure that may be used with any other aspect or portion thereof, the PD system includes sensors positioned along the line, and the sensors are configured to sense between the gas and the PD fluid present in the line.

[0049] In a 22nd aspect of the disclosure that may be used with any other aspect or portion thereof, the control unit is configured to open at least one gas valve when the PD fluid pressure in the disinfection loop reaches or exceeds the threshold PD fluid pressure and the output of the sensor indicates the gas present in the line.

[0050] In a 23rd aspect of the disclosure that may be used with any other aspect or portion thereof, the control unit is configured to close at least one gas valve when the output of the sensor indicates the PD fluid present in the line.

[0051] In a 24th aspect of the disclosure that may be used with any other aspect or portion thereof, the acid is citric acid, the PD fluid contains bicarbonate, and the gas is carbon dioxide (“CO2”) gas.

[0052] In a 25th aspect of the disclosure, which may be used in conjunction with any other aspect or portion thereof, a peritoneal dialysis ("PD") system includes a PD fluid pump, a disinfection loop that includes the PD fluid pump and that enables PD fluid to be used to disinfect the disinfection loop, and an acidic solution source positioned and arranged to supply an acidic solution to the disinfection loop during a disinfection sequence in which the PD fluid is used.

[0053] In a 26th aspect of the disclosure, which may be used in conjunction with any other aspect or portion thereof, the PD system includes an acidic solution valve positioned between the disinfection loop and the acidic solution source, and the acidic solution valve is opened to enable the acidic solution to be supplied to the disinfection loop during a disinfection sequence.

[0054] In a 27th aspect of the disclosure, which may be used in conjunction with any other aspect or portion thereof, the PD system includes a control unit and a conductivity sensor that outputs to the control unit, and the control unit is configured to operate the PD fluid pump and open the acidic solution valve to enable the acidic solution to be supplied to the disinfection loop during a disinfection sequence until the conductivity sensor output indicates that a desired amount of the acidic solution has been supplied.

[0055] In a 28th aspect of the disclosure, which may be used in conjunction with any other aspect or portion thereof, the PD system includes an acidic solution metering pump positioned between the disinfection loop and the acidic solution source, and the acidic solution metering pump is controlled to meter a desired amount of the acidic solution to the disinfection loop during a disinfection sequence.

[0056] In a 29th aspect of the present disclosure that may be used in conjunction with any other aspect or portion thereof, the disinfection loop includes an air trap and a pressure sensor positioned and arranged to sense the PD fluid pressure during the disinfection sequence, the pressure sensor outputs to a control unit, and the control unit is configured to open at least one gas valve located along at least one gas line leading to the top of the air trap when the PD fluid pressure reaches or exceeds a threshold PD fluid pressure due to gas formation caused by the mixing of the acidic solution and the PD fluid.

[0057] In a 30th aspect of the present disclosure that may be used in conjunction with any other aspect or portion thereof, the PD system includes a discharge line for discharging used PD fluid during treatment, and by opening at least one gas valve, the PD fluid pressure caused by gas formation due to the mixing of the acidic solution and the PD fluid can dissipate towards the discharge line.

[0058] In a 31st aspect of the present disclosure that may be used in conjunction with any other aspect or portion thereof, the control unit is further configured to perform at least one of (i) closing at least one PD fluid valve located adjacent to the air trap, or (ii) stopping the PD fluid pump when the PD fluid pressure reaches or exceeds a threshold PD fluid pressure.

[0059] In a 32nd aspect of the present disclosure that may be used in conjunction with any other aspect or portion thereof, the pressure sensor is positioned along one of at least one gas line in fluid communication with the disinfection loop to enable the pressure sensor to sense the PD fluid pressure during the disinfection sequence.

[0060] In a 33rd aspect of the present disclosure that may be used in conjunction with any other aspect or portion thereof, the PD fluid used to disinfect the disinfection loop is unused PD fluid, and the disinfection loop includes at least one reusable PD fluid supply line previously connected to a source of unused PD fluid.

[0061] In a 34th aspect of the disclosure that may be used with any other aspect or a part thereof, the disinfection loop includes at least one of (i) a reusable patient line, or (ii) an in-line heater, and the PD fluid used to disinfect the disinfection loop is heated by the in-line heater.

[0062] In a 35th aspect of the disclosure that may be used with any other aspect or a part thereof, any of the features, functions, and alternatives described in connection with any one or more of FIGS. 1-7 may be combined with any of the features, functions, and alternatives described in connection with any of the others of FIGS. 1-7.

[0063] Accordingly, an advantage of the disclosure is to provide a system for an automated peritoneal dialysis ("PD") cycler that helps prevent overpressure from occurring during disinfection.

[0064] Another advantage of the disclosure is to provide a system for a PD cycler that helps prevent overpressure from occurring during disinfection without the need for ventilation to the atmosphere, which can cause aseptic issues over time.

[0065] A further advantage of the disclosure is to provide a system for a PD cycler that helps prevent the accumulation of deposits during disinfection.

[0066] Additional features and advantages are described in, and will be apparent from, the following detailed description and the drawings. The features and advantages described herein are not all-inclusive, and in particular, many additional features and advantages will be apparent to one of ordinary skill in the art upon consideration of the drawings and description. Also, any particular embodiment need not have all of the advantages described herein, and it is expressly contemplated that individual advantageous embodiments may be claimed separately. 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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Mode for Carrying Out the Invention

[0074] Detailed Description System Overview Referring now to the drawings, and in particular to FIG. 1, the automated peritoneal dialysis (``PD'') system 10a of the present disclosure and related methodologies include a PD machine or cycler 20. The system 10a and cycler 20 seek to eliminate disposable articles as much as possible and instead provide most of its fluid conveyance section as reusable components, which are disinfected after the procedure. The fluid lines within the machine 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 - 24d extend. FIG. 1 further shows that a reusable patient line 26 also extends from the housing 22 of the machine or cycler 20. The reusable patient line 26 is typically longer than the reusable PD fluid supply lines 24a - 24d and may be wound or coiled within the housing by a spool or hose reel 28 when the reusable patient line 26 is not connected to a patient for treatment.

[0075] 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 supply line and the patient line may, 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 line 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 releasably attached to disinfection connectors 30a - 30d provided on the housing 22, respectively. The distal end 26d of the reusable patient line 26 is fluid - tightly and releasably attached to a patient line connector 32 provided on the housing 22 (or alternatively a disinfection cap). 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 are removed from or not connected to the connectors, respectively.

[0076] FIG. 1 also shows that the discharge line connector 34 can be releasably covered by a housing 22 with a movable, e.g., rotatable or slidable cover (not shown). The discharge line connector 34 receives a disposable discharge line 36 for treatment, which discharge line may extend to a discharge container, or a discharge bag, or a house drain. The disposable discharge line 36 is connected to the discharge line connector 34 during disinfection, as described below.

[0077] Disposable PD fluid or solution containers or bags (not shown since system 10a is in a disinfected configuration with the containers or bags removed) are respectively connected to the reusable PD fluid supply lines 24a - 24d. The distal ends 24e of the reusable PD fluid supply lines 24a - 24d may be color - coded and / or keyed to match the colored or keyed connectors of dedicated PD fluid containers or bags. The containers or bags may hold PD fluid of the same or different dextrose or glucose levels, e.g., 1.36% glucose PD fluid, 2.27% glucose PD fluid, 3.86% glucose PD fluid, PD fluid containing bicarbonate, and / or the last bag of different formulations of PD fluid, e.g., icodextrin.

[0078] It should be understood that any number of reusable PD fluid supply lines 24a - 24d and PD fluid containers or bags, including a single reusable PD fluid line and PD fluid container, or multiple reusable PD fluid lines and PD fluid containers, may be provided. In a further alternative embodiment, the PD fluid container or bag is replaced by an on - line PD fluid generation source that is connected to and in fluid communication with a single reusable PD fluid supply line.

[0079] In addition to the disposable drain line 36 (and associated container if used) and the disposable PD fluid container or bag, in one embodiment, the only other disposable component of the system 10a is a disposable filter set (not shown) removably connected by the patient at the distal end 26d of the reusable patient line 26 to provide the final stage of PD fluid filtration prior to delivery to the patient. In one embodiment, the disposable filter set is joined between the distal end 26d of the reusable patient line 26 and a patient transfer set that provides an indwelling PD catheter inserted into the patient.

[0080] Any one or more, or all, of the reusable PD fluid supply lines 24a-24d, the reusable patient line 26, the disinfection connectors 30a-30d, the patient line connector 32, the drain line connector 34, the drain line 36, the PD fluid container or bag, and the patient line filter set, may be made of any one or more plastics, such as polyvinyl chloride ("PVC"), or non-PVC materials such as polyethylene ("PE"), polyurethane ("PU"), polypropylene ("PP"), polyether ether ketone ("PEEK"), polycarbonate ("PC") or silicone.

[0081] FIG. 1 further shows that the reusable supply tube 52a extends from each of the reusable PD fluid supply lines 24a-24d, through each of the PD fluid supply valves 54a-54d, to the PD fluid in-line heater 56. In one embodiment, each of the valves of the PD cycler 20 including the PD fluid supply valves 54a-54d is an electrically actuated valve having a reusable valve body that blocks the flow of PD fluid through the body (e.g., when power is not supplied for a fail-safe operation) or allows the PD fluid to flow through the body (e.g., when power is supplied). 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, the PD fluid in-line heater 56 is also electrically actuated. For example, the PD fluid in-line heater 56 is a resistance heater having a reusable heater body that receives the PD fluid for treatment and disinfection heating. The in-line heater 56 in one embodiment can heat the PD fluid from room temperature or lower temperature (e.g., when the PD fluid is stored in a cold environment) to body temperature, e.g., 37° C., at a flow rate of up to at least 200 milliliters (ml) / minute.

[0082] A first temperature sensor 58a is located adjacent to the heater 56, e.g., downstream of the heater, to provide feedback for temperature control. Optionally, a second temperature sensor (not shown) may be provided upstream of the heater 56 so that the inlet temperature of the unused PD fluid can be taken into account in the heating algorithm. A second temperature sensor 58b is shown immediately downstream of the PD fluid pump 70, and this second temperature sensor 58b is provided, for example, as a second check function that the unused PD fluid exiting the PD fluid pump 70 is at the desired temperature for treatment, e.g., body temperature or 37° C.

[0083] In the illustrated embodiment, the flow switch 68 is positioned immediately upstream of the PD fluid in-line heater 56. The output from the flow switch 68 is used to confirm that there is a flow of unused PD fluid through the in-line heater 56. If the output (or lack thereof) from the flow switch 68 indicates that there is no or little flow of unused PD fluid that could be harmful to the in-line heater 56 when powered on, the system 10a stops power to the in-line heater 56 and, if necessary, stops treatment or disinfection while (i) attempting to find a remedy for the no or low flow situation or (ii) causing an audible, visual or audiovisual alarm or warning at the user interface 108. It should be noted that the cycler 20 of the system 10a may use additional or alternative hardware and / or software to cause PD fluid to flow when power is supplied to the heater 56.

[0084] The reusable tube 52b extends from the outlet of the PD fluid in-line heater 56 to the air trap 60 in the illustrated embodiment of FIG. 1. Any of the reusable tubes within the housing of the cycler 20, including the reusable tubes 52a and 52b, may 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”), polyetheretherketone (“PEEK”), polycarbonate (“PC”), or silicone. In one embodiment, one or more level sensors 62a and 62b are positioned adjacent to the air trap so that a desired level or desired level range of the PD fluid is maintained within the air trap 60. The fluid line valve 54e is positioned downstream of the air trap 60 in the illustrated embodiment and receives the unused heated PD fluid from the air trap 60. The gas line valve 54g is positioned along the gas line 52g extending from the upper end of the air trap 60. The air trap 60 may be closed upstream by the PD fluid supply valves 54a - 54d to drain the air trap when indicated by the output of the level sensor 62a or 62b.

[0085] The reusable fluid line 52c and the gas line 52g extend between the respective fluid line valve 54e and gas line valve 54g and a PD fluid pump 70 located within the housing 22 of the cycler 20. The PD fluid pump 70 includes a reusable pump body that receives the PD fluid for pumping. That is, the pump 70 does not require the PD fluid to flow through a disposable article such as a tube or cassette. The reusable pump body of the pump 70 itself receives the PD fluid. The PD fluid pump 70 may be a certain type of, for example, a piston pump, and since this piston pump is inherently accurate, a separate PD fluid volume measuring device such as a balance chamber or a flow meter is not required. Alternatively, the PD fluid pump 70 may be a less accurate gear or centrifugal pump that operates with a PD fluid quantity measuring device. By controlling the current level to the PD fluid pump, the PD fluid pump 70 is controllable to pump between the patient below the pressure limit. The positive pressure limit of the patient can be, for example, 1 to 5 psig (e.g., 2 psig (14 kPa)). The negative pressure limit of the patient can be, for example, -1.0 psig to -3.0 psig (e.g., -1.3 psig (-9 kPa)). The PD fluid pump 70 can, if necessary, supply lower pressures, for example, for infants or neonates. The PD fluid pump 70 is in one embodiment bidirectional and continuous, whereby a single pump may be provided.

[0086] FIG. 1 further shows that, in one embodiment, the unused PD fluid patient line valve 54f is positioned along a reusable unused PD fluid patient tube or line 52f between the downstream temperature sensor 58b and the spool or hose reel 28. The unused PD fluid patient tube or line 52f is in fluid communication with the unused PD fluid lumen of the double lumen reusable patient line 26 in one embodiment. The used PD fluid patient line valve 54u is positioned along a reusable used PD fluid patient tube or line 52u between the PD fluid pump 70 (via the cross 64a) and the spool or hose reel 28 in one embodiment. The used PD fluid patient tube or line 52u is in fluid communication with the used PD fluid lumen of the double lumen reusable patient line 26 in one embodiment. The drain line valve 54h is positioned along a reusable drain tube or line 52h extending from the tee 66 to the drain line connector 34.

[0087] The first patient pressure sensor 72a is positioned along the unused PD fluid patient tube or line 52f between the PD fluid pump 70 and the spool or hose reel 28 to measure the positive fluid pressure of the patient's PD. The second patient pressure sensor 72b is positioned along the gas line 52g to measure the negative patient PD fluid pressure during patient drainage (note that the gas line 52g can include gas, PD fluid, or combinations thereof, and any gas is at the same negative pressure as the used PD fluid via fluid communication at the cross 64a). The third and fourth pressure sensors 72c and 72d are positioned along the reusable disinfection tube or line 52d.

[0088] As described above, the patient line connector 32 is positioned in the PD cycler housing 22 and receives the double lumen reusable patient line 26 during disinfection and generally while the patient is not being treated. The patient line connector 32 in one embodiment includes a sealed fluid U-turn or 180-degree turn that allows a 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. Thus, the double lumen reusable patient line 26 is included in the disinfection loop. In an alternative embodiment, the patient line connector 32 may be replaced with a disinfection cap that includes a sealed fluid U-turn or 180-degree turn that allows a 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 disinfection cap may be attached to the end of the reusable patient line 26 so that it can be easily positioned when needed.

[0089] As described above, the drain line 36 is flexible and disposable in one embodiment and connects to a drain line connector 34 that extends from the housing 22 of the PD cycler 20 during treatment. After treatment, in one embodiment, the drain line 36 is left in place so that off-gases generated during the disinfection sequence can be vented into the drain line 36 towards the house drain or container drain. The drain line connector 34 receives an internal reusable drain tube or line 52h for (i) delivering used PD fluid to the drain line 36 during patient drainage and (ii) delivering air to the drain line 36 during priming. The drain line connector 34 also receives a vent tube or line 52v for delivering a gas, such as carbon dioxide (“CO2”) gas, to the drain line 36 during disinfection, as described in detail herein. A vent valve 54v is positioned along the vent tube or line 52v.

[0090] The reusable disinfection tube or line 52d shown in FIG. 1 extends to a second cross 64b together with the ventilation tube or line 52v and the used PD fluid patient tube or line 52u. The reusable disinfection tube or line 52d includes a disinfection valve 54s. As described in more detail herein, the disinfection tube or line 52d handles disinfection fluid or unused heated PD fluid, the ventilation tube or line 52v handles vented gas or CO2, while the used PD fluid patient tube or line 52u handles the used PD fluid during treatment and is split during disinfection, in which case, (i) the portion of the used PD fluid patient tube or line 52u between the first cross 64a and the second cross 64b transfers CO2 gas to the ventilation tube or line 52v, and (ii) the portion of the used PD fluid patient tube or line 52u between the second cross 64b and the spool or hose reel 28 transfers disinfected or unused PD fluid to or from the disinfection tube or line 52d.

[0091] FIG. 1 also shows that an acidic solution source 80 is connected to an acidic solution connector 82. The acidic solution line 52i extends from the solution connector 82 to a three-way acidic solution valve 54i, for example, the normally open port of the valve 54i. The three-way valve 54i also controls a bypass line 52y between the disinfection connectors 30c, 30d used during disinfection. A similar bypass line 52z is provided between the disinfection connectors 30a, 30b. The acidic solution source 80 holds the acidic solution used during the disinfection described herein. The acidic solution may be, for example, a citric acid solution, such as 50% citric acid. It should be understood that the acidic solution source 80 may be positioned substantially anywhere along the disinfection loop, for example, along the bypass line 52z or the disinfection tube or line 52d. The system 10b of FIG. 4 described below shows a preferred positioning for the acidic solution source 80.

[0092] Figure 1 further shows that the PD cycler 20 of the system 10a 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 pressure sensors 72a - 72d, temperature sensors 58a and 58b, flow switch 68, and optionally a conductivity sensor (not shown). The control unit 100 uses the pressure feedback from pressure sensors 72a and 72b to control the PD fluid pump 70 to pump unused PD and used PD within safe patient pressure limits and safe system limits. The control unit 100 uses the temperature feedback from temperature sensor 58a to control the in-line PD fluid heater 56 to heat the unused PD fluid to, for example, body temperature or 37°C. The control unit 100 uses the flow switch feedback from flow switch 68 to determine whether to supply power to the PD fluid in-line heater 56.

[0093] Also, the control unit 100 opens and closes PD fluid valves 54a - 54i, 54s, 54u, and 54v in combination with the operation of the PD fluid pump 70 and heater 56 to perform a priming sequence, a plurality of patient fill sequences, a plurality of patient drain sequences, and a post - PD treatment disinfection sequence. In the disinfection sequence, each reusable PD fluid supply line 24a - 24d is connected to its respective disinfection connector 30a - 30d, and the reusable patient line 26 is connected to the reusable patient line connector 32. The disinfection sequence prepares the PD cycler 20 for the next treatment. In one embodiment, the remaining unused PD fluid is heated after the final patient drain and used as a disinfection fluid for disinfection.

[0094] 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 that operates with one or more electromechanical buttons such as a touch screen and / or a membrane switch. Further, the user interface 108 may include one or more speakers for outputting alarms, warnings, and / or voice guidance commands. As shown in FIG. 1, a cycler 20 may be provided in the user interface 108 and / or it may be a remote user interface operating with the control unit 100. The control unit 100 includes a transceiver (not shown) and a network, for example, a wired or wireless connection to the Internet, for connecting to and functioning with a computer of a doctor or clinician, transmitting treatment data to a server of the doctor or clinician, and receiving prescription instructions from the server of the doctor or clinician.

[0095] Referring now to FIG. 2, a disinfection loop 90 including disinfected lines and components is highlighted. All other lines and components described in connection with FIG. 1 are provided but are generally not numbered in FIG. 2 for ease of explanation. The disinfection loop 90 includes a patient line connector 32 (with a line having dots introduced in a generally counterclockwise direction) (including its U-turn or 180-degree turn), both lumens of a reusable double-lumen patient line 26, a portion of a used PD fluid patient tube or line 52u between a spool or hose reel 28 and a second cross 64b, a reusable disinfection tube or line 52d, reusable PD fluid supply lines 24a-24d, bypass lines 52y, 52z, and reusable tubes or lines 52a-52c and 52f. The disinfection loop 90 also includes the inside of all flow components and sensors positioned along the above lines.

[0096] The control unit 100 may arrange specific valves along the disinfection loop 90 during disinfection. For example, the PD fluid supply valve 54a may be arranged to open and close during disinfection to allow the disinfection fluid to flow through the supply valve 54a or to be completely extruded through the reusable PD fluid supply line 24a. The control unit 100 may also sequentially operate the PD fluid pump 70 in the forward and reverse states during disinfection so that the disinfection fluid can flow clockwise and counterclockwise through the disinfection loop 90. The control unit 100 may also heat the disinfection fluid, such as unused PD fluid, to a desired disinfection temperature, such as 70°C to 90°C, in the in-line heater 56.

[0097] Deliver the disinfection-generated gas to the drain When using unused PD fluid as the disinfection fluid, if it contains bicarbonate, calcium carbonate may be formed in the disinfected flow path and flow components of the disinfection loop 90 of the PD machine or cycler 20. Therefore, acid from the acid solution source 80 is supplied during disinfection to prevent the formation of calcium carbonate. In one embodiment, the control unit 100 operates the PD fluid pump 70 at a specific flow rate and pressure and opens the acid solution valve 54i for a specific time to meter a desired amount of citric acid (or other) acid solution into the disinfected flow path and the flow components of the disinfection loop 90, and the determined time can be determined and tested empirically. In an alternative embodiment, the PD machine or cycler 20 includes, for example, a temperature-compensated conductivity cell (not shown but can be located anywhere along the disinfection loop, for example, along the reusable disinfection tube or line 52d), and this conductivity cell is used to provide feedback to the control unit 100 so that the acid solution valve 54i is opened until a desired conductivity is reached within the disinfection loop 90. In other alternative embodiments, a small, for example, essentially accurate acid solution metering pump (not shown) under the control of the control unit 100 is provided to meter a desired amount of acidic (e.g., citric acid) solution into the disinfection loop 90.

[0098] When the heated PD solution used for disinfection contains a bicarbonate component, the acidic solution causes the bicarbonate to release CO2 gas into the disinfection loop 90. In a closed disinfection loop 90, the released CO2 gas increases the pressure within the disinfection loop, which may promote internal leakage and affect the reliability of certain disinfected components positioned along the loop, such as the PD fluid pump 70.

[0099] In FIG. 2, to prevent the pressure increase due to gas or CO2 formation from reaching a point where it can affect the reliability of components, the control unit 100 of the system 10a may monitor the pressure within the disinfection loop 90 using the output from one or more pressure sensors, such as any one or more of the pressure sensors 72a - 72d, during disinfection (the pressure sensor 72b senses the disinfection pressure via fluid communication with the first cross 64a). When the pressure reaches a specific threshold exceeding a typical disinfection operating pressure that can be, for example, 10 kPa (1.5 psig), in one embodiment, the control unit 100 first checks that the disinfection fluid (e.g., heated unused PD fluid mixed with the acidic solution) within the air trap 60 of the PD machine or cycler 20 is below the upper threshold. Here, the control unit 100 may also check that the disinfection fluid has not reached the upper level sensor 62a. The control unit 100 performs this check to protect the PD fluid entering the gas line 52g. For example, an example of a threshold pressure exceeding the operating pressure of 10 kPa (1.5 psig) can be 20 kPa (2.9 psig). That is, in one example, the control unit 100 looks for an overpressure reaching 20 kPa (2.9 psig), which is approximately twice the specified operating pressure, as measured, for example, by the pressure sensor 72b.

[0100] When the control unit 100 determines overpressure and determines that the fluid level in the air trap 60 is not too high, it closes the disinfection valve 54e upstream of the air trap 60 and the open valves 54a to 54d to fluidly isolate the air trap. Further, the control unit 100 stops the pumping of the disinfection fluid by the PD fluid pump 70. The control unit 100 shown in FIG. 3 further opens (i) the gas line valve 54g, (ii) the used PD fluid patient line valve 54u, and (iii) the ventilation valve 54v to depressurize the pressurized CO2 gas and flow it through the discharge line connector 34 along the line indicated by the arrow in FIG. 3 from above the air trap 60 to the discharge line 36. The path for depressurizing the CO2 gas in the illustrated embodiment includes the gas line 52g, the portion between the crosses 64a and 64b of the used PD fluid patient tube or line 52u, the ventilation tube or line 52v, and the discharge line 36.

[0101] When the CO2 gas is appropriately depressurized to, for example, atmospheric pressure or 0 kPa, or in some cases a typical disinfection operating pressure such as 10 kPa (1.5 psig), so that it is sensed by the pressure sensor 72b output to the control unit 100, the control unit closes (i) the gas line valve 54g, (ii) the used PD fluid patient line valve 54u, and (iii) the ventilation valve 54v, opens the disinfection fluid valve 54e and any one or more desired upstream valves 54a - 54d, and activates the PD fluid pump 70 and the in-line heater 56 to continue disinfection. The depressurization sequence described just now is repeated as many times as necessary before the disinfection of the disinfection loop 90 (for example, while the disinfection fluid, such as PD fluid, is being heated for disinfection), and in some cases during the disinfection of the disinfection loop 90. In one example, while the disinfection fluid is being heated for disinfection, the flexible discharge line 36 is left in a predetermined position, and the depressurization sequence is performed one or more times with the discharge line 36 in the predetermined position to receive the removed CO2 gas. When the disinfection fluid is heated to the disinfection temperature, the user interface 108 audibly, visually, or aurally prompts the patient or user to then remove the discharge line 36 from the discharge line connector 34, after which the discharge line connector is capped via the discharge line cap 34c to fluidly close the disinfection loop 90 for the disinfection sequence.

[0102] The above-described depressurization sequence for removing CO2 gas from the discharge line 36 is described as being caused by overpressure due to the formation of CO2 gas. It is also stated that the depressurization sequence may be performed once or multiple times. In various embodiments, (i) the trigger for the depressurization sequence and (ii) the total time required to appropriately dissipate the CO2 gas pressure are functions of (a) the sensed pressure within the disinfection loop 90, (b) the time elapsed since the start of CO2 gas generation or the end of the previous depressurization sequence, (c) the volume of CO2 gas to be dissipated (calculated, for example, by the control unit 100 knowing the citric acid (or other) acid concentration and the disinfection fluid temperature), and / or (d) some previous depressurization sequences that have already been performed, and may depend on any one or more of them.

[0103] It should be understood that the aforementioned decompression sequence does not require a separate relief valve or hydrophobic air vent that may present aseptic issues (however, such valves and / or vents can be used if desired). Pathogens in the above decompression sequence are forced to completely move through the flexible discharge line 36 and are isolated during disinfection via the closed ventilation valve 54v and the closed discharge line valve 54h.

[0104] Similarly, in an alternative decompression sequence that does not require a separate relief valve or hydrophobic air vent, the control unit 100 of the PD machine or cycler 20 instead pumps a disinfection gas or CO2 into the discharge line 36 through one or more PD fluid pumps such as the PD fluid pump 70. Here, the control unit 100 can close the disinfection fluid valve 54e and open the gas line valve 54g so that the PD fluid pump 70 can draw and discharge the disinfection gas or CO2 from above the air trap 60. To draw the disinfection gas or CO2 from above the air trap 60, the control unit 100 opens the patient line valve 54f and closes the discharge line valve 54h, and then causes the PD fluid pump 70 to draw a volume of disinfection gas or CO2 equal to the inner tubular volume between above the air trap 60 and the tee 66 along the gas line 52g from the air trap 60. Then, the PD fluid patient line valve 54f is closed and the discharge line valve 54h is opened to allow the PD fluid pump 70 to discharge the removed volume of disinfection gas or CO2 gas. Any one or more of the above triggers and / or timing factors (a)-(d) can also be used in any disinfection sequence including the use of the PD fluid pump 70.

[0105] Figure 4 shows an alternative PD system 10b for removing and discharging disinfection gas or CO2 gas. The PD system 10b includes many of the same components as the PD system 10a that includes the disinfection loop 90, and they are given the same numbers and include all the structures, functions and alternative forms described above for those components. One of the main differences from Figure 4 is that the acidic solution source 80 is provided at a preferred position downstream of the PD fluid pump 70 along the unused PD fluid portion of the disinfection loop 90. In one embodiment, the PD fluid pump 70 is used to pump to the discharge line 36 from which CO2 gas can be removed. Using the PD fluid pump 70 helps minimize the amount of PD fluid required to flush the CO2 gas. As shown in Figure 4, placing the acidic solution source 80 downstream of the PD fluid pump 70 makes it impossible to pump CO2 gas to the patient during treatment (with the PD fluid pump 70 pumping in the forward delivery direction). Also, placing two valves 54j (two-way valve) and 54k (three-way valve) between the acidic solution source 80 and the unused patient tube or line 52f provides redundancy in preventing (i) the acid from being delivered to the patient and (ii) the PD fluid from being pumped to the acidic solution source 80 to dilute the acidic solution. The system 10b also includes a further recirculation line 54t having a recirculation valve 52t under the control of the control unit 100.

[0106] Furthermore, the administration or amount of acid (e.g., citric acid) delivered at the start of the disinfection sequence is improved in system 10b of FIG. 4. Here, before the system 10b introduces the acid dosage, the system adjusts the pressure at the acidic solution source 80 to atmospheric pressure or the last known pressure recorded at the acidic solution source 80. To use the last known pressure, during the administration of the acid, the PD fluid pump 70 operates in the reverse direction with a set amount of strokes corresponding to the dosage / one-shot output to draw the prescribed dosage of acid into the disinfection loop 90. At the end of the acid administration, the control unit 100 records the pressure measured by the pressure sensor 72a. This pressure is then stored as the starting input pressure at the acidic solution source 80 and used during the next disinfection sequence to improve the acid dosage accuracy. Such pressure control can be applied to any embodiment of any of the systems 10a - 10c described herein.

[0107] FIG. 5 shows an example output of the aforementioned decompression sequence. The top line (dotted line) is a baseline showing the pressure present from offgassed CO2 when bicarbonate PD fluid is used and the decompression sequence of system 10a is not performed. The Δ line and the x line are examples of PD fluids containing an acidic solution that results in the production of CO2 gas by-products, e.g., citric acid, combined with a bicarbonate (e.g., Physioneal® PD fluid commercially available from the assignee of the present disclosure). Here, the pressurized CO2 gas is released as described above when the pressure reaches or exceeds the threshold pressure. In the tests conducted up to the plot of FIG. 5, the threshold pressure is set at 10 kPa (1.5 psig). However, during the disinfection of system 10, while 10 kPa (1.5 psig) is likely to be within the operating pressure range, the threshold pressure for when to trigger the release of pressure can be significantly higher. As shown in FIG. 5, the pressure increase due to offgassed CO2 is significantly reduced by the decompression in the Δ line and the x line relative to the non-decompressed dotted line.

[0108] The unmarked lines are for a specific PD fluid, namely Dianeal® PD fluid, marketed by the assignee of the present disclosure, which does not contain bicarbonate and thus does not require the injection of a scale removal fluid such as citric acid during disinfection. Thus, the unmarked non-bicarbonate lines can be interpreted as model lines for the Δ line and the x line. The difference between the bicarbonate Δ line and the x line is that with the x line, the patient removes the disposable drain line 36 and covers the drain line connector 34 with the drain line cap 34c (Figs. 1-3) at the start of or at time t0 of the x line test. With the Δ line, the patient instead removes the disposable drain line 36 and waits for a specified period, 480 seconds in the example of Fig. 5 (Figs. 1-3), to cover the drain line connector 34 with the drain line cap 34c. During the waiting period or while the disinfection sequence is being performed, the disinfection fluid is heated to the disinfection temperature to disinfect by-products or produce CO2 gas. In the Δ line, the CO2 gas is vented for only, for example, 480 seconds while the disposable drain line 36 is present. After the disposable drain line 36 is removed, no further CO2 gas is vented from the system. However, the illustrated venting period is long enough to keep the Δ line pressure well below the dotted baseline pressure. The x line is a reference line where the disposable drain line 36 remains in place throughout the test so that CO2 gas can be vented throughout the test. As shown, both the Δ line and the x line generally run along non-bicarbonate lines and have a pressure much lower than the dotted baseline, which indicates the pressure present when bicarbonate PD fluid is used and the decompression sequence of system 10a is not performed. Also, the Δ line pressure does not increase as much over the x line pressure.

[0109] Delivery of Disinfection-Generated Gas to Acidic Solution Source FIG. 6 shows a further alternative PD system 10c. The PD system 10c includes many of the same components as the PD system 10a, which are given the same numbers and include all of the structures, functions, and alternative forms described above for those components. In particular, the system 10c includes a 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 system 10c includes an in-line dialysis fluid heater 56, reusable lines or tubes 52a and 52b, PD fluid supply valves 54a-54d, an air trap 60 operating with respective upper and lower level sensors 62a and 62b, a disinfectant fluid valve 54e, a gas line valve 54g located along the gas line 52g, a reusable line or tube 52c leading to the dialysis fluid pump 70, temperature sensors 58a and 58b, pressure sensors 72a, 72b, 72c and 72d, respective reusable unused and used patient tubes or lines 52f and 52u, a hose reel 28, a double lumen reusable patient line 26, a reusable drain tube or line 52h extending to the drain line connector 34 and having a drain line valve 54h, a vent line 52v having a vent valve 54v, and a reusable recirculation or disinfectant tube or line 52d operating with respective disinfectant valves 54s. A third recirculation or disinfectant tube or line 52y extends between the disinfectant connectors 30c and 30d for use during disinfection. A fourth recirculation or disinfectant tube or line 52z extends between the disinfectant connectors 30a and 30b for use during disinfection. The above lines and components form a disinfection loop 90 that is disinfected after a treatment. Each of the pump 70, heater 56, valves, and sensors is controlled by and / or outputs to the control unit 100.

[0110] One of the main differences from System 10c is that the acidic solution source 80, the acidic solution connector 82, and the acidic solution line 52i are moved from the positions shown in FIGS. 1 - 3, whereby the acidic solution line 52i instead extends to the gas line 52g that extends above the air trap 60. Accordingly, the recirculation or disinfection tube or line 52y extends directly between the disinfection connectors 30c and 30d instead of the three - way acidic solution valve 54i of System 10a that is removed in System 10c. The two - way acidic solution valves 54j and 54k are provided along the acidic solution line 52i to add redundancy to prevent acidic solutions such as citric acid from leaking during treatment or otherwise flowing into the treatment path (e.g., into lines 52c, 52f and into the unused PD fluid lumen of the dual - lumen reusable patient line 26).

[0111] Another addition seen in System 10c is the priming sensor 74 that outputs to the control unit 100. The priming sensor 74 of the illustrated embodiment is positioned along the gas line 52g, but alternatively may be positioned along the acidic solution line 52i. The priming sensor 74 is configured to detect whether a CO2 gas - to - acid, e.g., citric acid, or PD fluid (mixed with the acid) is positioned within, e.g., flowing through, the gas line 52g and / or the acidic solution line 52i. The priming sensor 74 in various embodiments is an ultrasonic, optical, inductive, capacitive or magnetic sensor that outputs to the control unit 100.

[0112] The test showed that when using citric acid as a scale remover and heating the disinfected PD fluid to 85°C, for example, adding 2.1 ml of 50% (by weight) citric acid to 300 ml (approximate volume of the disinfection loop 90) of bicarbonate-containing PD fluid generated 110 ml of CO2 gas. The advantage of the positioning of the acidic solution source 80, the acidic solution connector 82, and the acidic solution line 52i within the system 10c is that disinfection-generated gases such as carbon dioxide (“CO2”) can be delivered to and held within the empty space of the acidic solution source 80. The container of the acidic solution source 80 is flexible in one embodiment and is, for example, a polymer bag made of any of the materials discussed herein, which can expand when receiving CO2 gas and contract when the CO2 gas is removed from the bag.

[0113] During the disassembly of the system 10c after treatment, the patient or user connects the distal end 26d of the reusable patient line 26 to the patient line connector 32 provided on the housing 22, connects the distal ends 24e of the reusable PD fluid supply lines 24a - 24d to the disinfection connectors 30a - 30d (as shown in FIG. 6), removes the disposable drain line 36, whereby the movable, e.g., rotatable or slidable drain connector cover closes in a sealed state over the drain line connector 34. The control unit 100 then energizes and opens the valves 54e, 54j, 54k, 54f, and 54s to draw a desired amount of scale removal fluid, e.g., 50% (by weight) citric acid, from the acidic solution source 80 into the PD fluid pump 70 and deliver it to the disinfection loop 90. The control unit 100 also reads the output from the priming sensor 74 to confirm that citric acid has been injected into the PD fluid over the commanded number of strokes of the PD fluid pump 70.

[0114] Next, the control unit 100 biases the valves 54e, 54f, 54s, 54b, and 54c to an open state, heats the PD fluid mixed with citric acid to a desired disinfection temperature, for example, 85°C, in the PD fluid heater 56, and causes the heated PD fluid to circulate around the disinfection loop 90, for example, periodically, through the PD fluid pump 70 so that an appropriate amount of disinfection is performed. The control unit 100 can switch any desired valve and reverse the flow direction of the PD fluid pump 70 one or more times during the disinfection sequence.

[0115] During and / or for some time before and / or after disinfection of the disinfection loop 90, the control unit 100 can enter a pressure release mode. In one embodiment, the control unit 100 enters the pressure release mode when the pressure measured by one or more pressure sensors 72a - 72d located along the disinfection loop 90 reaches or achieves a threshold pressure, e.g., 10 kPa (1.5 psig) or any delta pressure exceeding the disinfection operating pressure described herein. The control unit 100 can also read the output of the upper level sensor 62a to ensure that the PD fluid level in the air trap 60 is lower than the upper level sensor 62a. Next, the control unit 100 energizes the open citric acid valves 54j and 54k to allow pressurized CO2 gas to flow into the container of the acidic solution source 80. During this time, the control unit 100 also refers to the output of the priming sensor 74 to confirm that gas rather than fluid is present and flowing. If fluid is detected, the control unit 100 closes the citric acid valves 54j and 54k. When the pressure measured by one or more pressure sensors 72a - 72d drops below the threshold pressure, e.g., 10 kPa (1.5 psig), the control unit 100 closes the citric acid valves 54j and 54k to prevent PD fluid from flowing into the container of the acidic solution source 80. Also, in one embodiment, when the output from the upper level sensor 62a to the control unit 100 indicates that the PD fluid mixed with citric acid has reached the upper level sensor 62a, the control unit 100 closes the citric acid valves 54j and 54k. In one embodiment, the control unit 100 is configured to enter the pressure release mode as many times as necessary during (and possibly slightly before and / or after) the disinfection sequence.

[0116] After the disinfection sequence, the control unit 100 no longer monitors the pressure measured by one or more pressure sensors 72a to 72d for the overpressure of the disinfection product gas. It is contemplated that the CO2 gas remains in the container of the acidic solution source 80 until the next procedure, at which point a new disposable discharge line 36 is connected to the discharge line connector 34. The control unit 100 opens the citric acid valves 54j and 54k, the valve 54g and the discharge valve 54h, and causes the PD fluid pump 70 to draw the CO2 gas from the container of the acidic solution source 80 and push it towards the discharge line 36. The control unit 100 monitors the output of the priming sensor 74 to confirm that there is and the gas is flowing rather than fluid during the removal of the CO2 gas from the container of the acidic solution source 80. The output of the output priming sensor 74 (which senses citric acid or other acids) and / or one or more pressure sensors such as the pressure sensor 72b, the output priming sensors can be monitored by the control unit 100 to know when to stop the PD fluid pump 70 from drawing the CO2 gas from the container of the acidic solution source 80. Then, the CO2 gas remaining in the disinfection loop 90 is primed to be discharged via the PD fluid before starting the next procedure.

[0117] The above-described pressure reduction sequence for removing the CO2 gas from the container of the acidic solution source 80 is described as being caused by overpressure due to the formation of the CO2 gas. It is also stated that the pressure reduction sequence may be performed one or more times. Similar to the system 10a, in various embodiments of the system 10a, (i) the trigger for the pressure reduction sequence and (ii) the total time required to appropriately dissipate the CO2 gas pressure are (a) the sensed pressure within the disinfection loop 90, (b) the time elapsed since the start of CO2 gas generation or the end of the previous pressure reduction sequence, (c) the amount of CO2 gas to be dissipated (e.g., calculated by the control unit 100 knowing the citric acid (or other) acid concentration and the disinfection fluid temperature), and / or (d) a function of any one or more of several previous pressure reduction sequences that have already been performed and may depend thereon.

[0118] Referring now to Figure 7, test results are shown for a system 10c using the method of releasing CO2 gas to a container of the acidic solution source 80 of the present disclosure. The top line (dotted line) is a baseline indicating the pressure present from off-gassed CO2 when the depressurization sequence of system 10c is not executed. The unmarked line is for a particular PD fluid commercially available by the assignee of the present disclosure, namely Dianeal® PD fluid, which does not contain bicarbonate and thus does not require injection of a scale removal fluid such as citric acid during disinfection. The Δ line and the x line are examples of PD fluids containing bicarbonate (e.g., Physioneal® PD fluid commercially available by the assignee of the present disclosure) combined with an acidic solution, such as citric acid. Here, pressurized CO2 gas is released to the container of the acidic solution source 80 when the pressure reaches 10 kPa (1.5 psig) after 2.1 ml of 50% (by weight) citric acid is added to the PD fluid (e.g., 300 ml) for heating and disinfection. As shown, the pressure increase due to off-gassed CO2 is mitigated and repeatedly reduced along both the Δ line and the x line curves. For both the Δ line and the x line curves, the output of the upper level sensor 62a operating in the air trap 60 is used as the limit of the release of CO2 gas to the acidic solution source 80. The Δ line indicates that only a portion of the CO2 gas is released to the acidic solution source 80 when the air trap 60 is filled with PD fluid up to the upper level sensor 62a at the start of the disinfection sequence. The x line shows a more preferred curve where some gas (e.g., air) is already present in the air trap 60 at the start of the disinfection sequence. Here, CO2 gas exhaust may be performed throughout the disinfection sequence, resulting in a lower pressure curve than the Δ line.

[0119] 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. Accordingly, such variations and modifications are intended to be within the scope of the appended claims.

Claims

Claim 1 A peritoneal dialysis ("PD") system comprising: a PD fluid pump; a disinfection loop including the PD fluid pump, the disinfection loop being adapted to use PD fluid to disinfect the disinfection loop; an air trap located along the disinfection loop; at least one gas valve located along at least one gas line leading to the upper part of the air trap; a pressure sensor positioned and arranged to sense the PD fluid pressure within the disinfection loop during a disinfection sequence; a control unit, wherein the pressure sensor outputs to the control unit, and the control unit is configured to open at least one gas valve when the PD fluid pressure within the disinfection loop reaches or exceeds a threshold PD fluid pressure due to gas formation caused during the disinfection sequence; A PD system comprising the above components. Claim 2 The PD system according to claim 1, wherein the gas formation is caused by mixing the PD fluid with an acidic solution. Claim 3 The PD system according to claim 1, wherein the control unit is configured to check that the PD fluid level within the air trap is not too high before opening the at least one gas valve. Claim 4 The PD system according to claim 1, further comprising a drain line for draining used PD fluid during treatment, and by opening the at least one gas valve, the PD fluid pressure caused by the gas formation can be dissipated towards the drain line. Claim 5 The PD system according to claim 1, wherein the control unit is further configured to perform at least one of (i) closing at least one PD fluid valve located adjacent to the air trap, or (ii) stopping the PD fluid pump when the PD fluid pressure reaches or exceeds the threshold PD fluid pressure. Claim 6 The PD system according to claim 1, wherein the pressure sensor is located along one of the at least one gas lines in fluid communication with the disinfection loop such that the pressure sensor can sense the PD fluid pressure during the disinfection sequence. Claim 7 The second pressure sensor that outputs to the pressure sensor or the control unit senses the dissipation of the PD fluid pressure after opening the at least one gas valve, and the control unit is further configured to close the at least one gas valve and continue the disinfection sequence when receiving an output indicating the dissipation of the PD fluid pressure. The PD system according to claim 1.

8. The PD system according to claim 1, wherein the opening of the at least one gas valve is configured such that gas can dissipate from the upper part of the air trap through one of the at least one gas lines towards the drain.

9. The control unit is further configured to open the at least one gas valve or keep it open for a period of time based on one or more of (i) the amount of gas, (ii) the duration since the start of gas formation, and / or (iii) the number of times the control unit has previously opened the at least one gas valve. The PD system according to claim 1.

10. A peritoneal dialysis (“PD”) system, A PD fluid pump, A disinfection loop including the PD fluid pump, the disinfection loop being configured to allow the use of PD fluid to disinfect the disinfection loop. An acidic solution source containing an acid for use during the disinfection sequence. A drain line positioned and arranged to discharge used PD fluid during treatment. A gas line, At least one gas valve positioned along the gas line, the at least one gas valve enabling fluid communication between the gas line and the drain line. A pressure sensor positioned and arranged to sense the PD fluid pressure within the disinfection loop during the disinfection sequence. A control unit, the pressure sensor outputs to the control unit, and the control unit is configured to open the at least one gas valve when the PD fluid pressure within the disinfection loop reaches or exceeds a threshold PD fluid pressure due to gas formed by mixing the PD fluid and the acid during the disinfection sequence. By opening the at least one gas valve, the PD fluid pressure caused by gas formation can dissipate towards the drain line. A PD system comprising

11. The PD system according to claim 10, including a heater configured to heat the PD fluid and the acid to a disinfection temperature during the disinfection sequence.

12. The PD fluid contains bicarbonate, and the gas formed is carbon dioxide (``CO ２ 2'') gas, the PD system according to claim 10.

13. The PD system according to claim 10, configured such that upon opening of the at least one gas valve, gas can dissipate from the upper part of the air trap through one of the at least one gas line towards the discharge line.

14. The PD system according to claim 10, wherein the control unit is configured to check that the PD fluid level in the air trap is not too high before opening the at least one gas valve.

15. The PD system according to claim 10, wherein the control unit is further configured to open or keep open the at least one gas valve based on one or more of (i) the amount of gas, (ii) the duration since the start of gas formation, and / or (iii) the number of times the control unit has previously opened the at least one gas valve.

16. The PD system according to claim 10, wherein the control unit is further configured to maintain the pressure in the acidic solution source equal to the pressure recorded in the acidic solution source at the start of acid administration for the disinfection sequence, which is the pressure at the end of acid administration for the previous disinfection sequence.

17. A peritoneal dialysis (“PD”) system, a PD fluid pump, a disinfection loop including the PD fluid pump, the disinfection loop being configured to allow the use of PD fluid to disinfect the disinfection loop, an air trap positioned along the disinfection loop, at least one gas valve positioned along at least one gas line leading to the upper part of the air trap, a pressure sensor positioned and arranged to sense the PD fluid pressure in the disinfection loop during the disinfection sequence A control unit, wherein the pressure sensor outputs to the control unit, and the control unit causes at least one gas valve to open to pump a predetermined amount of gas from the air trap to the PD fluid pump when the PD fluid pressure in the disinfection loop reaches or exceeds a threshold PD fluid pressure due to gas formation caused during the disinfection sequence. A control unit configured as such. A PD system comprising the same. **Claim 18** The PD system according to claim 17, including a patient line valve positioned along the patient line, wherein the control unit opens the patient line valve when the PD fluid pump pumps the predetermined amount of gas from the air trap. **Claim 19** The PD system according to claim 17, including a discharge line valve positioned along the discharge line, wherein the control unit closes the patient line valve and opens the discharge line valve after pumping the predetermined amount of gas from the air trap so that the PD fluid pump delivers the gas to the discharge line. **Claim 20** The control unit is further configured to open the at least one gas valve to cause the PD fluid pump to pump, or keep the at least one gas valve open for a period of time while the PD fluid pump is pumping, based on one or more of (i) the amount of gas, (ii) the duration since the start of gas formation, and / or (iii) the number of times the control unit has previously opened the at least one gas valve. The PD system according to claim 17.

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