Dialysis system with low volume peritoneal dialysis patient fill temperature control

Abstract

A peritoneal dialysis ("PD") system includes: a PD fluid pump; a dual lumen patient line comprising a fresh PD fluid lumen and a used PD fluid lumen; a filter kit in fluid communication with the fresh PD fluid lumen and the used PD fluid lumen; a valve disposed with the patient's delivery kit or with the filter kit; and a control unit configured to, after patient discharge: (i) when the valve is a manual valve, prompt a patient or caregiver to close the valve, or (ii) when the valve is a motorized or pneumatic control valve, cause the valve to automatically close. The control unit is further configured to cause the PD fluid pump to pump fresh heated PD fluid into the fresh PD fluid lumen with the valve closed to transfer unheated PD fluid from the fresh PD fluid lumen through the filter kit into the used PD fluid lumen. A corresponding method is also disclosed.

Description

Technical Field

[0001] The present disclosure relates generally to medical fluid therapy, and in particular to dialysis fluid therapy requiring fluid heating. Background Art

[0002] For various reasons, a person's renal system may fail. Kidney failure causes a variety of physiological disturbances. For example, it is no longer possible to balance water and minerals or to excrete the daily metabolic load. In addition, toxic end products of metabolism, such as urea, creatinine, uric acid, etc., may accumulate in the patient's blood and tissues.

[0003] Decreased kidney function and especially kidney failure requires treatment through dialysis. Dialysis removes waste products, toxins and excess water from the body that would otherwise be removed by the normally functioning kidneys. Dialysis treatment to replace kidney function is vital for many people because this treatment is life-saving.

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

[0005] Hemofiltration ("HF") is an alternative renal replacement therapy that relies on the convective transport of toxins from the patient's blood. HF is achieved by adding a replacement fluid, or substitution fluid, to an extracorporeal circuit during treatment. During HF treatment, the replacement fluid, as well as the patient's accumulated fluid between treatments, is ultrafiltered, providing a convective transport mechanism that is particularly beneficial in removing intermediate and large molecules.

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

[0007] Most HD, HF and HDF treatments are performed at centers. Today there is a trend toward home hemodialysis ("HHD"), in part because HHD can be performed daily, providing treatment benefits over in-center hemodialysis treatments, which are typically performed every two or three weeks. Studies have shown that more frequent treatments can remove more toxins and waste products and reduce interdialytic fluid overload than patients who receive less frequent but potentially longer treatments. Patients who receive more frequent treatments do not experience as many down cycles (fluctuations in fluids and toxins) as in-center patients, who have accumulated toxins for two or three days before treatment. In some areas, the nearest dialysis center may be miles from the patient's home, resulting in door-to-door treatment time taking up a large part of the day. Treatment at a center close to the patient's home may also take up a large part of the patient's day. HHD can be performed at night or during the day while the patient is relaxing, working or engaging in other productive activities.

[0008] Another type of renal failure therapy is peritoneal dialysis ("PD"), which infuses a dialysis solution (also called dialysis fluid) into the patient's peritoneal cavity via a catheter. The dialysis fluid contacts the peritoneum in the patient's peritoneal cavity. Waste products, toxins, and excess water pass from the patient's bloodstream through the capillaries in the peritoneum and enter the dialysis fluid due to diffusion and osmosis, i.e., an osmotic gradient occurs across the membrane. An osmotic agent in the PD dialysis fluid provides the osmotic gradient. Used or consumed dialysis fluid is discharged from the patient, thereby removing waste products, toxins, and excess water from the patient. This cycle is repeated, for example, multiple times.

[0009] 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 treatment. Here, the patient manually connects an implanted catheter to a drain to allow used or consumed dialysis fluid to drain from the peritoneal cavity. The patient then switches the fluid connection so that the patient's catheter is connected to a fresh PD fluid bag to inject fresh PD fluid into the patient's body through the catheter. The patient disconnects the catheter from the fresh PD fluid bag and allows the dialysis fluid to reside in the peritoneal cavity, where the transfer of waste, toxins, and excess water occurs. After the residence period, the patient repeats the manual dialysis procedure, for example four times a day. Manual peritoneal dialysis requires a large amount of time and effort from the patient, leaving ample room for improvement.

[0010] Automated peritoneal dialysis ("APD") is similar to CAPD in that dialysis treatment includes a drain cycle, a fill cycle, and a dwell cycle. However, an automated PD machine automatically performs these cycles, typically while the patient is sleeping. The PD machine relieves the patient from having to manually perform treatment cycles and from having to deliver supplies during the day. The PD machine is fluidly connected to an implanted catheter, to a supply source or bag of fresh PD fluid, and to a fluid drain. The PD machine pumps fresh PD fluid from a supply source of dialysis fluid through the catheter and into the patient's peritoneal cavity. The PD machine also allows the dialysis fluid to remain in the cavity and allows the transfer of waste, toxins, and excess water to occur. The supply source may include multiple liters of dialysis fluid, which may include multiple bags of solution.

[0011] The PD machine pumps used or spent dialysate from the patient's peritoneal cavity through a catheter to a drain. As with the manual process, several drain, fill, and dwell cycles occur during dialysis. The "last fill" may occur at the end of an APD treatment. The last fill fluid may remain in the patient's peritoneal cavity until the start of the next treatment, or it may be manually drained at some point during the day.

[0012] The PD machine also warms the PD fluid to body temperature, such as 37°C, before delivery to the patient's peritoneal cavity. During the patient dwell phase, which can last for several hours, the patient line extending from the PD machine to the patient's delivery set (leading to an indwelling PD catheter) remains filled with fluid, typically patient effluent. The fluid in the patient line cools to room temperature during the patient dwell and is returned to the patient's peritoneal cavity unheated at the start of the next patient fill. For most patients, small amounts of unheated fluid are not a problem. But for small-volume patients, such as pediatric patients, even small amounts of unheated fluid delivered to the peritoneal cavity can be uncomfortable at best.

[0013] Therefore, there is a need for an improved way to deliver PD fluid to low volume PD patients. Summary of the invention

[0014] The present disclosure provides an automated peritoneal dialysis ("PD") system that improves PD fluid filling for low-volume PD patients (e.g., pediatric patients). The system includes a PD machine or cycler. The PD machine is configured to deliver fresh, heated PD fluid to the patient at a pressure of, for example, 14 kPa (2.0 psig) or higher. The PD machine is capable of removing spent PD fluid or effluent from the patient at a pressure of, for example, -9 kPa (-1.3 psig) or higher. Fresh PD fluid is delivered to the patient via a double-lumen patient line and is first heated to body fluid temperature, such as 37°C. The heated PD fluid is then pumped through the fresh PD fluid lumen of the double-lumen patient line to a disposable filter kit. The disposable filter kit is in fluid communication with the fresh PD fluid lumen and the spent PD fluid lumen of the double-lumen patient line, which, in one embodiment, is heat sterilized and reusable. The disposable filter kit includes a sterilizing-grade filter membrane that can further filter the fresh PD fluid. In one embodiment, the disposable filter set is provided as a terminal filter of a PD machine, which has been heat sterilized between treatments. Any pathogens that may remain after sterilization (however unlikely) will be filtered out of the PD fluid through the sterilization grade filter membrane.

[0015] During the subsequent patient stay, the fresh PD fluid remaining in the fresh PD fluid lumen cools from body temperature to approximately ambient temperature. For low fill volume patients, initially filling the patient with cooler PD fluid may cause at least patient discomfort. Therefore, it is contemplated that at the end of each patient discharge (for which there is a subsequent patient fill), the user interface of the PD system and machine of the present disclosure prompts the patient or caregiver to close a manual valve, which may be provided with the patient's transfer kit or provided with the disposable filter kit. When the manual valve is closed, the manual valve causes the unheated fluid in the fresh PD fluid lumen to be purged from the fresh PD fluid lumen into the spent PD fluid lumen. Notably, a patient discharge may end in the following circumstances: (i) when the PD machine records that a specified amount of spent PD fluid or effluent has been cleared from the patient, (ii) when the control unit of the PD machine determines a low patient discharge flow rate, which indicates that the patient is empty or nearly empty, or (iii) or when the control unit determines that the patient discharge pressure increases, which also indicates that the patient is empty or nearly empty. At the end of the patient discharge determined by any one or more of (i) to (iii), the user interface prompts the patient or caregiver to close the manual valve in an audible, visual, or audio-visual manner.

[0016] After being prompted to close the manual valve, the user interface may display a confirmation button that the patient or caregiver presses to confirm that the manual valve has been closed. At the same time, or after pressing the confirmation button, in one embodiment, the control unit causes the PD fluid pump to perform a pressure test by attempting to pump PD fluid (e.g., a small amount, such as five milliliters ("ml")) to the patient with the appropriate PD machine valve open. If the manual valve has been properly closed, the pressure sensor of the PD machine will detect a rapid rise in positive pressure in the closed line. If the manual valve is not properly closed, the pressure sensor will not be able to detect the characteristics of the positive pressure or the expected rapid rise. In response, the control unit is configured to again cause the user interface to prompt the patient or caregiver to close the manual valve in an audible, visual, or audio-visual manner. The above procedure is repeated until the control unit confirms that the manual valve has been closed.

[0017] After confirming that the manual valve is closed, the control unit causes the appropriate PD machine valve to open so that the heated PD fluid can be delivered to the disposable filter kit, pushing the unheated PD fluid into the used PD fluid lumen and toward the machine discharge port. The control unit causes the PD fluid pump to pump fresh heated PD fluid (e.g., 30 to 50 ml) at least equivalent to the fresh PD fluid lumen volume into the fresh PD fluid lumen of the double lumen patient line (e.g., a reusable double lumen patient line). A corresponding volume of unheated room temperature PD fluid is transferred from the fresh PD fluid lumen to the used PD fluid lumen via the disposable filter kit. A similar corresponding volume of unheated room temperature used PD fluid or effluent is transferred from the used PD fluid lumen to the line or tube within the PD machine, thereby pushing the used PD fluid toward the discharge line connected to the PD machine.

[0018] After the PD fluid pump pumps fresh heated PD fluid equivalent to the fresh PD fluid lumen volume (e.g., 30 to 50 ml) to fill the fresh PD fluid lumen, the control unit prompts the patient or caregiver via the user interface to open the manual valve located at the patient's transfer kit or at the connector of the disposable filter kit. After the user interface provides a prompt to open the manual valve, the user interface may again display a confirmation button that the patient or caregiver presses to confirm that the manual valve has been opened. After the confirmation button has been pressed, the control unit causes the PD fluid pump to pump the patient's prescribed fill volume of fresh heated PD fluid into the patient's peritoneal cavity with the appropriate PD machine valve open. The above process is repeated for each low volume patient fill.

[0019] In an alternative and in a preferred embodiment, after the user interface provides a prompt to open the manual valve, the control unit can perform a pressure test to determine whether the manual valve is open. The pressure test can be performed by pumping a small amount of fluid (e.g., five milliliters ("ml")) into the manual valve. If the manual valve has been properly opened, the associated pressure sensor will not measure a significant pressure increase, after which the patient's prescribed fill volume of fresh, heated PD fluid is pumped into the patient's peritoneal cavity. In another alternative embodiment, the control unit confirms the opening of the manual valve via a pressure test in which the PD fluid pump applies a small amount of positive or negative pressure at the manual valve before instructing the user to open the valve. When the manual valve has been properly opened, the associated pressure sensor measures a significant pressure increase or decrease, after which the patient's prescribed fill volume of fresh, heated PD fluid can be pumped into the patient's peritoneal cavity.

[0020] According to the disclosure set forth herein, and without limiting the disclosure in any way, in a first aspect of the disclosure (which may be combined with any other aspect or portion thereof), a peritoneal dialysis ("PD") system comprises: a housing; a PD fluid pump, the housing accommodating the PD fluid pump; a double-lumen patient line extending from the housing and comprising a fresh PD fluid lumen and a used PD fluid lumen; a filter kit, the filter kit being fluidically connected to the fresh PD fluid lumen and the used PD fluid lumen of the double-lumen patient line; a valve, the valve being provided with a patient's delivery kit or with the filter kit, the valve being positioned so that when the valve is closed, PD fluid is forced from the fresh PD fluid lumen into the used PD fluid lumen; and a control unit, the PD fluid pump being controlled by the control unit. The control unit is configured to: (i) prompt the patient or caregiver to close the valve when the valve is a manual valve, or (ii) automatically close the valve when the valve is an electric control valve or a pneumatic control valve after the patient discharges. The control unit is also configured to cause the PD fluid pump to pump fresh heated PD fluid into the fresh PD fluid lumen after the valve is closed to transfer unheated PD fluid from the fresh PD fluid lumen through the filter kit to the used PD fluid lumen.

[0021] In a second aspect of the present disclosure, which may be combined with any other aspect or portion thereof, the filter kit comprises a sterilizing grade filter membrane, wherein the transferred unheated PD fluid is transferred through the sterilizing grade filter membrane into the used PD fluid lumen.

[0022] In a third aspect of the present disclosure, which may be combined with any other aspect or portion thereof, the manual valve is a manual ball valve, a twist valve, a gate valve or a needle valve.

[0023] In a fourth aspect of the present disclosure, which may be combined with any other aspect or portion thereof, the PD system further comprises a pressure sensor. The control unit is further configured to cause the PD fluid pump to attempt to pump a test amount of fresh PD fluid into the fresh PD fluid lumen and monitor an output from the pressure sensor to determine whether the valve is closed.

[0024] In a fifth aspect of the present disclosure, which may be combined with any other aspect or portion thereof, the control unit is further configured to monitor the output from the pressure sensor to determine whether the valve is closed before causing the PD fluid pump to pump fresh, heated PD fluid into the fresh PD fluid lumen to transfer unheated PD fluid from the fresh PD fluid lumen through the filter kit and into the used PD fluid lumen.

[0025] In a sixth aspect of the present disclosure which may be combined with any other aspect or portion thereof, the control unit is further configured to monitor an output from the pressure sensor after the patient or a caregiver confirms that the manual valve has been closed.

[0026] In a seventh aspect of the present disclosure, which may be combined with any other aspect or part thereof, when the valve is a manual valve, prompting the patient or caregiver to close the valve includes providing a confirmation button for the patient or caregiver to press after closing the manual valve.

[0027] In an eighth aspect of the present disclosure, which may be combined with any other aspect or part thereof, the control unit is further configured to, after causing the PD fluid pump to pump fresh heated PD fluid into the fresh PD fluid lumen: (iii) when the valve is a manual valve, cause the patient or caregiver to be prompted to open the valve, or (iv) when the valve is an electrically controlled valve or a pneumatically controlled valve, cause the valve to open automatically.

[0028] In a ninth aspect of the present disclosure that may be combined with any other aspect or part thereof, when the valve is a manual valve, prompting the patient or caregiver to open the valve includes: providing a confirmation button for the patient or caregiver to press after opening the manual valve.

[0029] In a tenth aspect of the present disclosure which may be combined with any other aspect or portion thereof, the control unit is further configured to, after opening the valve, cause the PD fluid pump to pump a prescribed fill volume of fresh heated PD fluid to the patient.

[0030] In an eleventh aspect of the present disclosure, which may be combined with any other aspect or portion thereof, a peritoneal dialysis ("PD") system comprises: a housing; a PD fluid pump, the housing housing housing the PD fluid pump; a double lumen patient line extending from the housing and comprising a fresh PD fluid lumen and a spent PD fluid lumen; a valve provided with a patient delivery set, the valve being positioned so that when the valve is closed, PD fluid is forced from the fresh PD fluid lumen into the spent PD fluid lumen; and a control unit, the PD fluid pump being controlled by the control unit. The control unit is configured to, after a patient is drained: (i) prompt a patient or caregiver to close the valve when the valve is a manual valve, or (ii) cause the valve to close automatically when the valve is an electrically controlled valve or a pneumatically controlled valve. The control unit is further configured to cause the PD fluid pump to pump fresh heated PD fluid into the fresh PD fluid lumen to transfer unheated PD fluid from the fresh PD fluid lumen to the used PD fluid lumen after the valve is closed.

[0031] In a twelfth aspect of the present disclosure, which may be combined with any other aspect or portion thereof, a peritoneal dialysis ("PD") system comprises: a housing; a PD fluid pump, the housing housing housing the PD fluid pump; a patient line extending from the housing; a filter kit, the filter kit being in fluid communication with the patient line; a valve, the valve being provided with a patient delivery kit or with the filter kit, the valve being positioned so that when the valve is closed, PD fluid is removed from the patient line; and a control unit, the PD fluid pump being controlled by the control unit. The control unit is configured to, after a patient is drained: (i) prompt a patient or a caregiver to close the valve when the valve is a manual valve, or (ii) automatically close the valve when the valve is an electrically controlled valve or a pneumatically controlled valve, the control unit being further configured to cause the PD fluid pump to pump fresh heated PD fluid into the patient line after closing the valve.

[0032] In a thirteenth aspect of the present disclosure, which may be combined with any other aspect or portion thereof, PD fluid is removed from the patient line to drain and backfilled with filtered air.

[0033] In a fourteenth aspect of the present disclosure, which may be combined with any other aspect or portion thereof, a peritoneal dialysis ("PD") system comprises: a housing; a PD fluid pump, the housing housing housing the PD fluid pump; a patient line extending from the housing; a valve, the valve being provided with a patient delivery kit, the valve being positioned so that when the valve is closed, PD fluid is removed from the patient line; and a control unit, the PD fluid pump being controlled by the control unit. The control unit is configured to, after a patient is discharged: (i) prompt the patient or a caregiver to close the valve when the valve is a manual valve, or (ii) cause the valve to close automatically when the valve is an electrically controlled valve or a pneumatically controlled valve. The control unit is further configured to cause the PD fluid pump to pump fresh, heated PD fluid into the patient line after closing the valve.

[0034] In a fifteenth aspect of the present disclosure that may be combined with any other aspect or portion thereof, a peritoneal dialysis ("PD") method includes: determining that a prescribed patient fill is a low volume patient fill, wherein the patient fill is performed by operating a fresh PD fluid lumen of a double lumen patient line with the PD machine, the double lumen patient line also including a spent PD fluid lumen. The method further includes entering a low volume mode after determining the low volume patient fill, wherein prior to the low volume patient fill, closing the valve, the closed valve being positioned to enable the PD machine to transfer cooled PD fluid residing in the fresh PD fluid lumen to the spent PD fluid lumen by filling the fresh PD fluid lumen with fresh heated PD fluid.

[0035] In a sixteenth aspect of the present disclosure, which may be combined with any other aspect or portion thereof, the PD method includes: when it is determined that the prescribed patient fill is not a low volume patient fill, performing the prescribed patient fill without transferring the cooled PD fluid residing in the fresh PD fluid lumen.

[0036] In a seventeenth aspect of the present disclosure, which may be combined with any other aspect or portion thereof, the PD method includes: after transferring the cooled PD fluid residing in the fresh PD fluid lumen to the used PD fluid lumen, opening the valve to enable the PD machine to perform the low volume patient fill.

[0037] In an eighteenth aspect of the present disclosure which may be combined with any other aspect or portion thereof, closing and opening the valve includes manually closing and opening the valve.

[0038] In a nineteenth aspect of the present disclosure, which may be combined with any other aspect or portion thereof, closing and opening the valve includes prompting a patient or a caregiver to close and open the valve.

[0039] In a twentieth aspect of the present disclosure which may be combined with any other aspect or portion thereof, the PD method includes confirming that the valve is closed as a condition required for transferring cooled PD fluid into the used PD fluid lumen.

[0040] In a twenty-first aspect of the present disclosure, which may be combined with any other aspect or portion thereof, confirmation is performed via a button press on the PD machine.

[0041] In a twenty-second aspect of the present disclosure, which may be combined with any other aspect or portion thereof, the PD method includes confirming that the valve is closed by performing a pressure check on the fresh PD fluid lumen as a condition required for transferring cooled PD fluid into the used PD fluid lumen.

[0042] In a twenty-third aspect of the present disclosure, which may be combined with any other aspect or portion thereof, the PD method includes allowing a patient or caregiver to override or deactivate the low volume mode so that the PD machine is able to perform the low volume fill without transferring cooled PD fluid residing in the fresh PD fluid lumen.

[0043] In a twenty-fourth aspect of the present disclosure, which may be combined with any other aspect or part thereof, Figures 1 to 3 Any one or more of the features, functions and alternatives described in any one or more of the above may be combined with Figures 1 to 3 Any features, functions and alternatives described in any other figure may be combined.

[0044] In view of the above aspects and the disclosure presented herein, it is an advantage of the present disclosure to provide an improved system and method for delivering PD fluids to a low volume PD patient.

[0045] Another benefit of the present disclosure is that a PD fluid system is provided that delivers PD fluid to a PD patient at body temperature (eg, 37°C).

[0046] Another advantage of the present disclosure is to provide a PD fluid system that removes effluent from a patient line prior to filling the patient.

[0047] Additionally, it is an advantage of the present invention to provide a PD fluid system that automatically reconfigures itself to warm the PD fluid prior to patient delivery when the system learns that the fill volume is low.

[0048] Additional features and advantages are described in, and will become apparent from, the following detailed description and accompanying 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 in view of the accompanying drawings and description. Furthermore, it is not necessary for any particular embodiment to have all of the advantages listed herein, and it is expressly contemplated that each advantageous embodiment is separately claimed. Furthermore, it should be noted that the language used in the specification has been selected primarily for readability and didactic purposes and not for the purpose of limiting the scope of the inventive subject matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 is a fluid flow diagram of one embodiment of a medical fluid (eg, PD fluid) system having the low patient fill volume structures and methods of the present disclosure.

[0050] Figure 2 is a front view of one embodiment of a valved patient transfer set or a valved disposable filter set of the present disclosure.

[0051] Figure 3 is a process flow diagram illustrating one embodiment of the present disclosure for operating a low volume patient fill. DETAILED DESCRIPTION

[0052] Referring now to the drawings, and in particular to Figure 1 , the structure and method of low volume patient filling of the present disclosure is illustrated by a peritoneal dialysis ("PD") system 10. The example system 10 includes a PD machine or cycler 20 and a control unit 100 having one or more processors 102, one or more memories 104, a video controller 106, and a user interface 108. The example user interface 108 may alternatively or additionally be a remote user interface, such as via a tablet or smartphone. The control unit 100 may also include a transceiver and a wired or wireless connection to a network (not shown) (e.g., the Internet) for sending treatment data to a physician or clinician server interfaced with a physician or clinician's computer, and receiving prescription instructions / changes from the physician or clinician server. In one embodiment, the control unit 100 controls all electrical components, fluid flow components, and heating components of the system 10 and receives outputs from sensors of the system 10. In the illustrated embodiment, the system 10 includes durable and reusable components that contact fresh PD fluid and used PD fluid, which requires the PD machine or cycler 20 to be sterilized, such as by heat sterilization, between treatments.

[0053] Figure 1The system 10 in the embodiment of the present invention includes an in-line resistance heater 56, reusable supply lines or tubes 52a1 to 52a4 and 52b, an air collector 60 operating with corresponding upper and lower level sensors 62a and 62b, an air collector valve 54d, a vent valve 54e located along a vent line 52e, a reusable line or tubing 52c, a PD fluid pump 70, temperature sensors 58a and 58b, pressure sensors 78a, 78b1, 78b2 and 78c, reusable patient tubing or lines 52f and 52g with corresponding valves 54f and 54g, a double lumen reusable patient line 28, a hose reel 80 for retrieving the patient line 28, a reusable drain tubing or line 52i extending to the drain line connector 34 and having a drain line valve 54i, and reusable recirculating sterile tubing or lines 52r1 and 52r2 operating with corresponding sterile valves 54r1 and 54r2. A third recirculating or sterile tubing or line 52r3 extends between the sterile connectors 30a and 30b for use during sterilization. A fourth recirculating or sterile tubing or line 52r4 extends between the sterile connectors 30c and 30d for use during sterilization.

[0054] System 10 also includes PD fluid containers or bags 38a-38c (e.g., containing the same or different formulations of PD fluid) connected to distal ends 24d of reusable PD fluid lines 24a-24c, respectively. System 10d also includes a fourth PD fluid container or bag 38d connected to distal end 24d of reusable PD fluid line 24e. Fourth PD fluid container or bag 38d may hold the same or a different type of PD fluid (e.g., icodextrin) than the PD fluid provided in PD fluid containers or bags 38a-38c. In one embodiment, reusable PD fluid lines 24a-24c and 24e extend through an orifice (not shown) defined or provided by housing 22 of circulator 20.

[0055] In the illustrated embodiment, the system 10 includes four sterile connectors 30a-30d for connection to the distal ends 24d of the reusable PD fluid lines 24a-24c and 24e, respectively, during sterilization. The system 10 also provides a patient line connector 32 that includes an inner lumen (e.g., a U-shaped lumen) that directs fresh or used dialysis fluid from one PD fluid lumen of the connection distal end 28d of the double lumen reusable patient line 28 to the other PD fluid lumen for sterilization. Reusable supply tubing or lines 52a1-52a4 are in communication with the reusable supply lines 24a-24c and 24e, respectively. The reusable supply tubing or lines 52a1-52a3 operate with valves 54a-54c, respectively, to allow PD fluid from the desired PD fluid container or bag 38a-38c to be drawn into the circulator 20. In the example shown, three-way valve 94a allows the control unit 100 to select between (i) 2.27% (or other) glucose dialysis fluid from container or bag 38b or 38c and (ii) icodextrin from container or bag 38d. In the embodiment shown, icodextrin from container or bag 38d is connected to the normally closed port of three-way valve 94a.

[0056] In one embodiment, system 10 is configured such that during a patient fill, drain line 52i is fluidly connected downstream of PD fluid pump 70. In this manner, if drain valve 54i fails or somehow leaks during a patient fill of patient P, fresh PD fluid is pushed along disposable drain line 36 rather than spent PD fluid potentially being drawn into pump 70. In one embodiment, disposable drain line 36 is removed for sterilization, wherein drain line connector 34 is capped by cap 34c to form a closed sterilization circuit. PD fluid pump 70 may be an inherently accurate pump, such as a piston pump, or a less accurate pump, such as a gear pump that operates in conjunction with a flow meter (not shown) to control the flow and volume of fresh and spent PD fluid.

[0057] The system 10 may further include a leak detection disc 82 located at the bottom of the housing 22 of the circulator 20 and a corresponding leak detection sensor 84 output to the control unit 100. In the example shown, the system 10 is provided with an additional pressure sensor 78c located upstream of the PD fluid pump 70, which allows the suction pressure of the pump 70 to be measured to help the control unit 100 more accurately determine the pump volume. In the embodiment shown, the additional pressure sensor 78c is located along the vent line 52e, which can be filled with air or a mixture of air and PD fluid, but it should still be at the same negative pressure as the PD fluid located in the PD fluid line 52c.

[0058] Figure 1The system 10 in the example of the embodiment includes redundant pressure sensors 78b1 and 78b2, the output of one of the pressure sensors 78b1 and 78b2 is used for pump control, as described herein, and the output of the other pressure sensor is a safety or watchdog output to ensure that the reading of the control pressure sensor is accurate. The pressure sensors 78b1 and 78b2 are located along the pipeline including the third recirculation valve 54r3. In another example, the system 10 can use one or more cross-connects that are located at Figure 1 Marked with an X in the figure, this can (i) reduce the total amount and volume of internal reusable tubing, (ii) reduce the number of valves required, and (iii) minimize the portion of the fluid circuit shared by fresh and used PD fluids.

[0059] exist Figure 1 The system 10 in the example of also includes a source of acid, such as a citric acid container or bag 66. The citric acid container or bag 66 is in selective fluid communication with the second three-way valve 94b via a citric acid valve 54m disposed along the citric acid line 52m. In one embodiment, the citric acid line 52m is connected to a normally closed port of the second three-way valve 94b to provide a redundant valve between the citric acid container or bag 66 and the PD fluid circuit during treatment. The redundant valve ensures that no citric acid (or other acid) reaches the treatment fluid line during treatment. Instead, citric acid (or other acid) is used during the disinfection process.

[0060] In one embodiment, the control unit 100 uses feedback from any one or more of the pressure sensors 78a-78c to enable the PD machine 20 to deliver fresh, heated PD fluid to the patient at a pressure of, for example, 14 kPa (2.0 psig) or higher. This pressure feedback is used to enable the PD machine 20 to remove spent PD fluid or effluent from the patient at a pressure of, for example, -9 kPa (-1.3 psig) or higher. This pressure feedback can be used in a proportional, integral, derivative ("PID") pressure program for pumping fresh and spent PD fluid at a desired positive or negative pressure.

[0061] Under control of the control unit 100, the resistive heater 56 installed in the line can heat the fresh PD fluid to body temperature, such as 37°C, for delivery to the patient P at a desired flow rate. In one embodiment, the control unit 100 uses feedback from the temperature sensor 58a in the PID temperature routine to pump fresh PD fluid to the patient P at a desired temperature.

[0062] Figure 1Also shown is that the system 10 includes and uses a disposable filter kit 40 that is in fluid communication with the fresh PD fluid lumen and the used PD fluid lumen of the double lumen reusable patient line 28. The disposable filter kit 40 includes a disposable connector 42 that is connected to the distal end 28d of the reusable patient line 28. The disposable filter kit 40 also includes a connector 44 that is connected to the patient's delivery kit. The disposable filter kit 40 also includes a sterilizing grade filter membrane 46 that further filters the fresh PD fluid. In one embodiment, the disposable filter kit 40 is provided as a terminal filter of the PD machine 20, which has been heat sterilized between treatments. Any pathogens that may remain after sterilization (although unlikely) are filtered out of the PD fluid via the sterilizing grade filter membrane 46 of the disposable filter kit 40.

[0063] Figure 2 The disposable filter set 40 and the transfer set 50 for the patient P are shown in more detail in FIG. Figure 2 As shown, the double lumen patient line 28 includes a fresh PD fluid lumen 28f and a spent PD fluid lumen 28u. The fresh PD lumen 28f carries fresh PD fluid from the PD machine 20 to and through the sterilization-grade filter membrane 46 of the disposable filter kit 40. The spent PD fluid lumen 28u carries spent PD fluid from the spent PD fluid side of the disposable filter kit 40 to the PD machine 20. Figure 2 Further explained, a short flexible line 64 is located between the disposable filter set 40 and the delivery set 50 of the patient P. The short flexible line 64 separates the generally rigid disposable filter set 40 and the patient's delivery set 50 so that they do not have to be connected together to form a large, generally rigid assembly that may cause discomfort to the patient.

[0064] It is expected that the fresh PD fluid lumen 28f will have an internal volume of about 30 to 50 ml, such as an internal volume of 35 ml. During the course of the patient's stay, such as a stay of one to two hours, this volume of fluid resides in the fresh PD fluid lumen 28f and is therefore cooled from the treatment temperature to room temperature. For PD patients with a typical fill volume of 1 to 2 liters, it is not a problem to initially receive 30 to 50 ml of unheated room temperature PD fluid because the patient will be quickly filled with heated fresh PD fluid at a high flow rate of 200 to 250 milliliters per minute (ml / min). However, for low volume patients, such as pediatric or infant patients, the fill volume can be much smaller, such as 300 ml or less. In addition, the fill flow rate for low volume patients is also lower, such as 150 ml / min or less, so the unheated room temperature initial fill from the PD fluid lumen 28f has a considerable comparative effect. In addition, due to the lower fill flow rate, it takes longer to receive the heated fresh PD fluid to heat the initial fill of unheated PD fluid. Therefore, the structure and method of the present disclosure are provided.

[0065] Figure 1 and Figure 2 As shown, one or both of the disposable filter kit 40 (e.g., at the connector 44) and / or the patient delivery kit 50 are provided with a manual valve 68, 168, such as a manual ball valve, twist valve, gate valve, or needle valve. The patient delivery kit 50 is typically provided with a valve 68, such as a twist valve, so that the disposable filter kit 40 does not need to provide a manual valve 168. In any case, at the end of the patient discharge, in one embodiment, the control unit 100 prompts the patient or caregiver to close the manual valve 68, 168 via the user interface 108. The patient discharge can be ended when (i) the PD machine 20 records that a specified amount of spent PD fluid or effluent has been removed from the patient, (ii) when the control unit 100 determines a low patient discharge flow, indicating that the patient is empty or nearly empty, or (iii) when the control unit 100 determines that the patient discharge pressure increases, which also indicates that the patient is empty or nearly empty. At the end of patient discharge as determined by any one or more of (i) to (iii), the user interface 108 audibly, visually, or audiovisually prompts the patient or caregiver to close the manual valve 68 , 168 .

[0066] After the user interface 108 provides a prompt to close the manual valves 68, 168, the user interface may display a confirmation button that the patient or caregiver presses to confirm that the manual valves 68 and 168 are closed. At the same time, or after the confirmation button is pressed, the control unit 100 causes the PD machine valves 94b and 54f to open toward the patient P, and the PD fluid pump 70 runs a pressure test by attempting to pump PD fluid (e.g., a small amount, such as five milliliters ("ml")) to the patient P. If the manual valves 68, 168 are properly closed, the pressure sensor 78a output to the control unit 100 will detect a rapid rise in positive pressure in the closed line. If the manual valves 68, 168 are not properly closed, the pressure sensor 78a will not detect the characteristic rapid rise in positive pressure, wherein the control unit 100 will cause the user interface 108 to prompt the patient or caregiver to close the manual valves 68, 168 in an audible, visual, or audio-visual manner. The above process is repeated until the control unit 100 confirms that the manual valves 68, 168 are closed.

[0067] Once it is confirmed that the manual valves 68, 168 are closed, the control unit 100 opens the PD machine valves 94b and 54f toward the patient P, and opens the PD machine valves 54r3 and 54r2 toward the disposable drain line 36. The control unit 100 causes the PD fluid pump 70 to pump fresh heated PD fluid (e.g., 30 to 50 ml) at least equivalent to the volume of the fresh PD fluid lumen along the patient tubing or line 52f within the PD machine 20 and into the fresh PD fluid lumen 28f of the reusable double lumen patient line 28. A corresponding volume of unheated room temperature PD fluid is transferred from the fresh PD fluid lumen 28f to the used PD fluid lumen 28u via the disposable filter kit 40. A similar corresponding volume of unheated room temperature used PD fluid or effluent is transferred from the used PD fluid lumen 28u to the tubing or tubes 52g and 52r2 located within the PD machine 20, thereby pushing the used PD fluid toward the drain line 36.

[0068] After the PD fluid pump 70 pumps fresh heated PD fluid equivalent to the volume of the fresh PD fluid lumen (e.g., 30 to 50 ml) to fill the fresh PD fluid lumen 28f, the control unit 100 prompts the patient or caregiver via the user interface 108 to open the manual valves 68, 168 located at the patient's delivery kit 50 or at the connector 44 of the disposable filter kit 40. After the user interface 108 provides a prompt to close the manual valves 68, 168, the user interface may again display a confirmation button that the patient or caregiver presses to confirm that the manual valves 68, 168 have been opened. After pressing the confirmation button, the control unit 100 causes the PD machine valves 94b and 54f to open toward the patient P, and causes the PD fluid pump 70 to pump the patient's prescribed fill volume of fresh heated PD fluid into the peritoneal cavity of the patient P. The above process is repeated for each low volume patient fill.

[0069] During treatment, the closing and opening of the manual valve 68, 168 at each patient fill requires effort by the patient or caregiver. However, it should be understood that low-volume patient fills do not occur frequently. Therefore, it is contemplated that the control unit 100 is programmed so that upon receiving a device prescription for treatment, such as from one or more memories 104, an external memory such as a universal serial bus ("USB") drive, or from a remote server, the control unit checks the prescribed fill volume specified in the device prescription. If the prescribed patient fill volume is not a low-volume patient fill, the control unit 100 continues with typical treatment in which the patient or caregiver is not prompted to close and open the manual valve 68, 168 before each patient fill. If the prescribed patient fill volume is a low-volume patient fill, such as 300 ml or less, the control unit 100 enters a low-fill volume mode in which the patient or caregiver is prompted to close and open the manual valve 68, 168 before each patient fill, as described herein.

[0070] PD treatment with typical patient fill volumes occurs primarily at the patient's home and at night while the patient is asleep. As described herein, many low-volume fills occur in pediatric patients who are not chronic renal failure patients, but who suffer from acute renal failure due to other illnesses or events (such as accidents). Here, the pediatric patient is treated in a hospital, such as in an intensive care unit, where a nurse is present to operate the PD machine 20. The closing and opening of the manual valves 68, 168 are performed by the nurse as one of the steps required to treat acute renal failure in pediatric patients. It is also conceivable that, in cases where, for example, chronic renal failure patients are small enough that their fill volumes are low fill volumes, the control unit 100 allows the low-volume mode to be replaced during treatment, or the low-volume mode to be disabled for all treatments. The patient can then choose to receive a fill of unheated PD fluid without having to manipulate the manual valves 68, 168 as described herein.

[0071] Figure 3 Method 110 summarizes the programming and operation of the control unit 100. At oval 112, the method 110 begins. At diamond 114, the control unit 100 determines whether the prescribed patient fill volume is a low volume patient fill volume, such as 300 ml or less. When the prescribed patient fill is not a low volume patient fill as determined at diamond 114, then at block 116, the control unit 100 causes PD therapy to proceed in a normal manner without flushing the fresh PD fluid lumen 28f of unheated PD fluid. When the prescribed patient fill is a low volume patient fill as determined at diamond 114, then at block 118, the control unit 100 causes the user interface 108 to prompt the patient or caregiver to close the manual valves 68, 168, and confirm such closure.

[0072] At diamond 120, the control unit 100 determines whether the patient or caregiver has confirmed the closure of the manual valves 68, 168. If not, the method 110 returns to block 118 and continues to prompt the patient or caregiver to close the manual valves 68, 168 and confirm such closure. When the patient or caregiver confirms that the manual valves 68, 168 are closed, as determined by diamond 120, the control unit 100 performs a pressure check at block 122 in the manner described herein to ensure that the manual valves 68 and 168 are fully closed. In an alternative embodiment, after prompting the patient or caregiver to close the manual valves 68, 168 at block 118, the control unit 100 periodically runs a pressure check.

[0073] At diamond 124, the control unit 100 determines whether the pressure check confirms that the manual valve 68, 168 is properly closed. If not, the method 110 returns to block 118 again and continues to prompt the patient or caregiver to close the manual valve 68, 168 and confirm such closure. When the pressure check confirms that the manual valve 68, 168 is properly closed, as determined at diamond 124, the control unit 100 causes the PD fluid pump 70 at block 126 to pump fresh heated PD fluid at least equivalent to the internal fresh fluid lumen volume into the fresh PD fluid lumen 28f with the appropriate PD machine valve open, thereby discharging the unheated PD fluid through the disposable filter set 40 into the used PD fluid lumen 29u, as described herein.

[0074] After delivering the heated PD fluid into the fresh PD fluid lumen 28f at block 126, the control unit 100 causes the user interface 108 to prompt the patient or caregiver to open the manual valve 68, 168 and confirm such opening at block 128. At diamond 130, the control unit 100 determines whether the patient or caregiver has confirmed the opening of the manual valve 68, 168. If not, the method 110 returns to block 128 and continues to prompt the patient or caregiver to open the manual valve 68, 168 and confirm such closing. If the patient or caregiver has confirmed the opening of the manual valve 68, 168, as determined at diamond 130, the control unit 100 causes the PD fluid pump 70 at block 132 to pump the prescribed low fill volume of fresh heated PD fluid into the patient's peritoneal cavity with the appropriate valve open.

[0075] In an alternative and in a preferred embodiment, for diamond 130, control unit 100 confirms the opening of valve 68, 168 via a pressure test, rather than via user confirmation. The pressure test may be performed by causing PD fluid pump 70 to pump a small amount of fluid (e.g., five milliliters ("ml")) to the patient at valve 68, 168. If manual valve 68, 168 has been properly opened, the associated pressure sensor (e.g., pressure sensor 78a) will not see a significant pressure increase, and then the patient's prescribed fill volume of fresh, heated PD fluid is pumped into the patient's peritoneal cavity at block 132. In another alternative embodiment of diamond 130, control unit 100 confirms the opening of valve 68, 168 via a pressure test in which PD fluid pump 70 applies a small amount of positive or negative pressure (e.g., 6.9 kPa (1 psig) or -6.9 kPa (-1 psig)) at the patient's valve 68, 68 before instructing the user to open the valve. When the manual valve 68, 168 is properly opened, the associated pressure sensor, such as pressure sensor 78a, will see a significant pressure increase or decrease, after which at block 132 the patient's prescribed fill volume of fresh heated PD fluid is pumped into the patient's peritoneal cavity.

[0076] At diamond 134, the control unit 100 determines whether there are other scheduled patient fills remaining in the current treatment. If not, the method 110 ends at oval 136. If it is determined at diamond 134 that there are other scheduled patient fills in the current treatment, the control unit 110 waits for the subsequent patient stay to end and waits to perform a subsequent drain at block 138, and then returns to block 118 to prompt the patient or caregiver to close the manual valve 68, 168 for the next low volume patient fill.

[0077] It should be understood that various changes and modifications to the current preferred embodiments described herein will be apparent to those skilled in the art. Therefore, the appended claims are intended to cover such changes and modifications. For example, the system 10 need not use redundant or durable components, need not employ sterilization, such as heat sterilization, but may employ a disposable kit having a disposable pumping portion that contacts the corresponding medical fluid. Such a disposable box may employ a double-lumen reusable patient line 28, and may or may not employ a disposable filter kit 40. Although a disposable filter kit 40 is not required as a terminal filter for systems that do not employ heat sterilization, a disposable filter kit 40 may still be provided as a terminal filter for online PD fluids if fresh PD fluids are made online at the time of use. Alternatively, PD fluid pumping using a disposable kit may be performed by a pneumatic pump actuation of a sheet of a disposable box of a disposable kit, via an electromechanical pump actuation of a sheet of a disposable box of a disposable kit, or via a peristaltic pump actuation of a pumping tube segment provided with the disposable kit.

[0078] Further optionally, although valves 68, 168 are described as manual valves, valves 68, 168 may alternatively be electrically or pneumatically controlled valves controlled by control unit 100. Here, control unit 100 may automatically perform the steps of method 110 at the end of discharge, and no manual action or confirmation by the patient or caregiver is required.

[0079] Still further optionally, while the system 10 and associated methods have been described using a dual lumen patient line 28, a single lumen patient line may be used. Here, the goal is not to replace cold PD fluid, as the single lumen patient line is instead filled with heated spent PD fluid or effluent from a previous drain. Rather, the goal is to remove spent PD fluid so that it does not return to a low volume patient where it may constitute a larger portion of a prescribed patient fill. Here, a disposable filter kit 40 or transfer kit 50 for the patient may be provided with a hydrophobic membrane that allows air to aseptically backfill spent PD fluid that is removed from the single lumen patient line for draining by the PD machine 20 when the valves 68, 168 are closed. With the valves 68, 168 still closed, the control unit 100 causes fresh heated PD fluid to be pumped into the single lumen patient line, thereby pushing sterile air through the hydrophobic membrane and toward the atmosphere. When all air has been removed to atmosphere and the patient line is filled with fresh heated PD fluid, the control unit 100 senses a pressure spike at pressure sensor 72a, at which point the single lumen patient line fill stops. Valves 68, 168 may then be opened for a prescribed patient fill using only fresh heated PD fluid.

Claims

1. A peritoneal dialysis ("PD") system comprising: case; a PD fluid pump, the housing containing the PD fluid pump; a double lumen patient line extending from the housing, the double lumen patient line comprising a fresh PD fluid lumen and a spent PD fluid lumen; a filter kit in fluid communication with the fresh PD fluid lumen and the spent PD fluid lumen of the double lumen patient line; a valve provided with a patient's delivery set or provided with the filter set, the valve being positioned such that when the valve is closed, PD fluid is forced from the fresh PD fluid lumen into the spent PD fluid lumen; and a control unit configured to control the PD fluid pump, the control unit further configured to, after discharge from a patient: (i) when the valve is a manual valve, prompting the patient or caregiver to close the valve, or (ii) when the valve is an electrically controlled valve or a pneumatically controlled valve, causing the valve to close automatically, Wherein, the control unit is further configured to cause the PD fluid pump to pump fresh heated PD fluid into the fresh PD fluid lumen after the valve is closed, so as to transfer unheated PD fluid from the fresh PD fluid lumen to the used PD fluid lumen through the filter kit.

2. The PD system according to claim 1, wherein: The filter kit includes a sterilizing grade filter membrane, and wherein the transferred unheated PD fluid is transferred through the sterilizing grade filter membrane and into the used PD fluid lumen.

3. The PD system according to claim 1 or 2, wherein: The manual valve is a manual ball valve, a twist valve, a gate valve or a needle valve.

4. The PD system according to claim 1, 2 or 3, further comprising a pressure sensor, wherein: The control unit is further configured to cause the PD fluid pump to attempt to pump a test volume of fresh PD fluid into the fresh PD fluid lumen and to monitor an output from the pressure sensor to determine whether the valve is closed.

5. The PD system according to claim 4, wherein: The control unit is further configured to monitor the output from the pressure sensor to determine whether the valve is closed before causing the PD fluid pump to pump fresh, heated PD fluid into the fresh PD fluid lumen to transfer unheated PD fluid from the fresh PD fluid lumen through the filter kit and into the used PD fluid lumen.

6. The PD system according to claim 4, wherein: The control unit is further configured to monitor the output from the pressure sensor after the patient or a caregiver confirms that the manual valve has been closed.

7. The PD system according to claim 1, wherein: When the valve is a manual valve, prompting the patient or the caregiver to close the valve includes: providing a confirmation button for the patient or the caregiver to press after closing the manual valve.

8. The PD system according to claim 1 or 7, wherein: The control unit is further configured to, after causing the PD fluid pump to pump fresh heated PD fluid into the fresh PD fluid lumen: (iii) when the valve is a manual valve, prompting the patient or caregiver to open the valve, or (iv) When the valve is an electric control valve or a pneumatic control valve, the valve is automatically opened.

9. The PD system according to claim 8, wherein: When the valve is a manual valve, prompting the patient or the caregiver to open the valve includes: providing a confirmation button for the patient or the caregiver to press after opening the manual valve.

10. The PD system according to claim 8, wherein: The control unit is further configured to, after opening the valve, cause the PD fluid pump to pump a prescribed fill volume of fresh, heated PD fluid to the patient.

11. A peritoneal dialysis ("PD") system comprising: case; a PD fluid pump, the housing containing the PD fluid pump; a double lumen patient line extending from the housing, the double lumen patient line comprising a fresh PD fluid lumen and a spent PD fluid lumen; a valve disposed with a patient's delivery set, the valve being positioned such that when the valve is closed, PD fluid is forced from the fresh PD fluid lumen into the spent PD fluid lumen; and a control unit configured to control the PD fluid pump, the control unit further configured to, after discharge from a patient: (i) when the valve is a manual valve, prompting the patient or caregiver to close the valve, or (ii) when the valve is an electrically controlled valve or a pneumatically controlled valve, causing the valve to close automatically, Wherein, the control unit is further configured to cause the PD fluid pump to pump fresh heated PD fluid into the fresh PD fluid lumen after the valve is closed, so as to transfer unheated PD fluid from the fresh PD fluid lumen to the used PD fluid lumen.

12. A peritoneal dialysis ("PD") system comprising: case; a PD fluid pump, the housing containing the PD fluid pump; a patient line extending from the housing; a filter kit in fluid communication with the patient line; a valve provided with a patient delivery set or provided with the filter set, the valve being positioned such that when the valve is closed, PD fluid is removed from the patient line; and a control unit configured to control the PD fluid pump, the control unit further configured to, after discharge from a patient: (i) when the valve is a manual valve, prompting the patient or caregiver to close the valve, or (ii) when the valve is an electrically controlled valve or a pneumatically controlled valve, causing the valve to close automatically, Wherein, the control unit is further configured to, after closing the valve, cause the PD fluid pump to pump fresh heated PD fluid into the patient line.

13. The PD system according to claim 12, wherein: PD fluid is removed from the patient line for draining and backfilled with filtered air.

14. A peritoneal dialysis ("PD") system comprising: case; a PD fluid pump, the housing containing the PD fluid pump; a patient line extending from the housing; a valve disposed with a patient delivery set, the valve being positioned such that when the valve is closed, PD fluid is removed from the patient line; and a control unit configured to control the PD fluid pump, the control unit further configured to, after discharge from a patient: (i) when the valve is a manual valve, prompting the patient or caregiver to close the valve, or (ii) when the valve is an electrically controlled valve or a pneumatically controlled valve, causing the valve to close automatically, Wherein, the control unit is further configured to, after closing the valve, cause the PD fluid pump to pump fresh heated PD fluid into the patient line.

15. The PD system according to claim 14, wherein: PD fluid is removed from the patient line for draining and backfilled with filtered air.

16. A peritoneal dialysis ("PD") method comprising: determining, via a control unit of the PD machine, that a prescribed patient fill is a low volume patient fill, wherein the patient fill is performed by operating a fresh PD fluid lumen of a double lumen patient line with the PD machine, the double lumen patient line also including a spent PD fluid lumen; and After determining the low volume patient fill, a low volume mode is entered via the control unit, in which the valve is closed before the low volume patient fill, and the closed valve is positioned to enable the PD machine to transfer the cooled PD fluid residing in the fresh PD fluid lumen to the used PD fluid lumen by filling the fresh PD fluid lumen with fresh heated PD fluid.

17. The PD method according to claim 16, further comprising: When it is determined by the control unit that the prescribed patient fill is not a low volume patient fill, the prescribed patient fill is performed via the PD machine without diverting cooled PD fluid residing in the fresh PD fluid lumen.

18. The PD method according to claim 16 or 17, further comprising: After transferring the cooled PD fluid residing in the fresh PD fluid lumen into the spent PD fluid lumen, the valve is opened via the control unit to enable the PD machine to perform the low volume patient fill.

19. The PD method according to claim 18, wherein: Closing and opening the valve includes causing the valve to be manually closed and opened.

20. The PD method according to claim 18, wherein: Closing and opening the valve includes prompting a patient or a caregiver to close and open the valve.

21. The PD method according to claim 16, further comprising: The valve is confirmed closed via the control unit as a condition required for transferring cooled PD fluid into the spent PD fluid lumen.

22. The PD method according to claim 21, wherein: The confirmation is done via a button press on the PD machine.

23. The PD method of claim 16, further comprising: The valve is confirmed closed via the control unit by performing a pressure check on the fresh PD fluid lumen as a condition required for transferring cooled PD fluid into the used PD fluid lumen.

24. The PD method according to claim 16, further comprising: Enabling a patient or caregiver via the control unit to override or deactivate the low volume mode enables the PD machine to perform the low volume fill without displacing cooled PD fluid residing in the fresh PD fluid lumen.

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