PERITONEAL DIALYSIS SYSTEM HAVING A PATIENT LINE FILTER

A peritoneal dialysis (“PD”) system (10) includes a PD machine (20); a patient line (50) extending from the PD machine (20); and a filter set (100) in fluid communication with the patient line (50), the filter set (100) including a filter membrane (120, e.g., a sterilizing grade filter membrane or a bacteria reduction filter membrane) positioned and arranged such that fresh PD fluid flows through the filter membrane (120) into a filtered fluid compartment (106f), wherein the filtered fluid compartment (106f) includes an outlet (1060) to a port (106p), and wherein the port (106p) is in fluid communication with a circumferential used PD fluid channel (106c) positioned and arranged to carry used PD fluid around the filter membrane (120) without contacting the filter membrane (120). A method for priming filter set (100) is also disclosed.

BACKGROUND

The present disclosure relates generally to medical fluid treatments and in particular to the filtering of treatment fluid during dialysis fluid treatments.

Due to various causes, a person's renal system can fail. Renal failure produces several physiological derangements. It is no longer possible to balance water and minerals or to excrete daily metabolic load. Toxic end products of metabolism, such as, urea, creatinine, uric acid and others, may accumulate in a patient's blood and tissue.

Reduced kidney function and, above all, kidney failure is treated with dialysis. Dialysis removes waste, toxins and excess water from the body that normal functioning kidneys would otherwise remove. Dialysis treatment for replacement of kidney functions is critical to many people because the treatment is lifesaving.

One type of kidney failure therapy is Hemodialysis (“HD”), which in general uses diffusion to remove waste products from a patient's blood. A diffusive gradient occurs across the semi-permeable dialyzer between the blood and an electrolyte solution called dialysate or dialysis fluid to cause diffusion.

Hemofiltration (“HF”) is an alternative renal replacement therapy that relies on a convective transport of toxins from the patient's blood. HF is accomplished by adding substitution or replacement fluid to the extracorporeal circuit during treatment. The substitution fluid and the fluid accumulated by the patient in between treatments is ultrafiltered over the course of the HF treatment, providing a convective transport mechanism that is particularly beneficial in removing middle and large molecules.

Hemodiafiltration (“HDF”) is a treatment modality that combines convective and diffusive clearances. HDF uses dialysis fluid flowing through a dialyzer, similar to standard hemodialysis, to provide diffusive clearance. In addition, substitution solution is provided directly to the extracorporeal circuit, providing convective clearance.

Most HD, HF, and HDF treatments occur in centers. A trend towards home hemodialysis (“HHD”) exists today in part because HHD can be performed daily, offering therapeutic benefits over in-center hemodialysis treatments, which occur typically bi- or tri-weekly. Studies have shown that more frequent treatments remove more toxins and waste products and render less interdialytic fluid overload than a patient receiving less frequent but perhaps longer treatments. A patient receiving more frequent treatments does not experience as much of a down cycle (swings in fluids and toxins) as does an in-center patient, who has built-up two or three days' worth of toxins prior to a treatment. In certain areas, the closest dialysis center can be many miles from the patient's home, causing door-to-door treatment time to consume a large portion of the day. Treatments in centers close to the patient's home may also consume a large portion of the patient's day. HHD can take place overnight or during the day while the patient relaxes, works or is otherwise productive.

Another type of kidney failure therapy is peritoneal dialysis (“PD”), which infuses a dialysis solution, also called dialysis fluid or PD fluid, into a patient's peritoneal chamber via a catheter. The PD fluid comes into contact with the peritoneal membrane in the patient's peritoneal chamber. Waste, toxins and excess water pass from the patient's bloodstream, through the capillaries in the peritoneal membrane, and into the PD fluid due to diffusion and osmosis, i.e., an osmotic gradient occurs across the membrane. An osmotic agent in the PD fluid provides the osmotic gradient. Used PD fluid is drained from the patient, removing waste, toxins and excess water from the patient. This cycle is repeated, e.g., multiple times.

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 PD fluid to drain from the patient's peritoneal cavity. The patient then switches fluid communication so that the patient catheter communicates with a bag of fresh PD fluid to infuse the fresh PD fluid through the catheter and into the patient. The patient disconnects the catheter from the fresh PD fluid bag and allows the PD fluid to dwell within the patient's peritoneal cavity, wherein the transfer of waste, toxins and excess water takes place. After a dwell period, the patient repeats the manual dialysis procedure, for example, four times per day. Manual peritoneal dialysis requires a significant amount of time and effort from the patient, leaving ample room for improvement.

APD is similar to CAPD in that the dialysis treatment includes drain, fill and dwell cycles. APD machines, however, perform the cycles automatically, typically while the patient sleeps. APD machines free patients from having to manually perform the treatment cycles and from having to transport supplies during the day. APD machines connect fluidly to an implanted catheter, to a source or bag of fresh PD fluid and to a fluid drain. APD machines pump fresh PD fluid from a dialysis fluid source, through the catheter and into the patient's peritoneal chamber. APD machines also allow for the PD fluid to dwell within the chamber and for the transfer of waste, toxins and excess water to take place. The source may include multiple liters of dialysis fluid, including several solution bags.

APD machines pump used PD fluid from the patient's peritoneal cavity, though the catheter, to drain. As with the manual process, several drain, fill and dwell cycles occur during dialysis. A “last fill” may occur at the end of the APD treatment. The last fill fluid may remain in the peritoneal chamber of the patient until the start of the next treatment, or may be manually emptied at some point during the day.

PD fluid needs to be sterile or very near sterile because it is injected into the patient's peritoneal cavity, and is accordingly considered a drug. While bagged PD fluid is typically properly sterilized for treatment, PD fluid made online or PD machines or cyclers that employ disinfection may need additional sterilization.

There is accordingly a need for an effective, low cost way of providing additional sterilization to fresh PD fluid before it is delivered to a patient.

SUMMARY

The present disclosure provides a peritoneal dialysis (“PD”) system having a PD machine or cycler that pumps fresh PD fluid through a patient line to a patient and removes used PD fluid from the patient via the patient line. The patient line may be reusable or disposable and in either case operates with and fluidly communicates with a filter set. If the patient line is reusable, the reusable patient line is connected to the filter set at the time of treatment. If the patient line is disposable, the filter set is merged into the disposable patient line in one embodiment. In either configuration, a distal end of the filter set may be connected to the patient's transfer set, which in turn communicates fluidly with the patient's indwelling catheter.

The PD machine or cycler may include a durable PD fluid pump that pumps PD fluid through the pump itself without using a disposable component, or a disposable type PD fluid pump including a pump actuator that actuates a disposable, fluid-contacting pumping component, such as a peristaltic pump tube or a flexible pumping chamber. The PD machine or cycler also includes a plurality of valves, which may likewise be flow-through and durable without operating with a disposable component, or be disposable type valves having valve actuators that actuate a disposable, fluid-contacting valve component, such as a tube segment or a cassette-based valve seat.

The pumps and valves are under the automatic control of a control unit provided by the machine or cycler. In an embodiment, the valves include a fresh PD fluid valve that the control unit opens to allow the PD fluid pump to pump fresh PD fluid through a fresh PD fluid lumen of a dual lumen patient line to the patient. The valves also include a used PD fluid valve that the control unit opens to allow the PD fluid pump to pump used PD fluid from the patient through a used PD fluid lumen of the dual lumen patient line. It should be appreciated that while a single PD fluid pump may be used, dedicated fresh and used PD fluid pumps may be used alternatively. Also, a single PD fluid pump may include multiple pumping chambers for more continuous PD fluid flow.

The fresh and used PD fluid lumens may again be reusable or disposable. In the instance in which the fresh and used PD fluid lumens are reusable, the lumens terminate with a connector that connects to a lumen-side connector of the filter set, which may be sealed to (e.g., ultrasonically sealed, heat sealed or solvent bonded) or molded with a body of the filter set. The body is in turn sealed to (e.g., ultrasonically sealed, heat sealed or solvent bonded) or molded with a transfer set-side connector that either connects directly to a mating connector of the patient's transfer set or to a mating connector of a short tube placed between the body and the patient's transfer set. The transfer set-side connector may alternatively be placed at the end of a short tube that extends from the body. Here, the body provides (e.g., is molded with) a transfer set-side port to which the short tube extends into or over for welding to the port. The body, lumen-side connector, and transfer set-side connector or transfer set-side port may be referred to herein as a filter housing.

The lumen-side connector and the body form a fresh PD fluid passageway and a used PD fluid passageway. The fresh PD fluid passageway extends through a fresh PD fluid port in the lumen-side connector and towards an inner wall located within the body of the filter housing. The inner wall forces the fresh PD fluid to change direction and flow over the wall into a pressurization compartment, which resides over the outside of a flat sheet filter membrane. The fresh PD fluid is pressurized within the pressurization compartment. The pressurization forces the fresh PD fluid through the pores of the flat sheet filter membrane and into a filtered fluid compartment of the body, which is bounded primarily by the inner surface of the flat sheet filter membrane and a bottom surface of the body. In an embodiment, a series of ribs extend up from the bottom surface of the body. The series of ribs support the flat sheet filter membrane both under positive patient filling pressure and negative patient draining pressure. The ribs are spaced apart however to allow fresh, filtered PD fluid to flow through the ribs.

The inner wall that forces fresh PD up and over the filter membrane in one embodiment extends all the way around the series of ribs. The continuous inner wall is located inside of a continuous outer sidewall of the body. A circumferential used PD fluid channel is accordingly formed between the continuous inner wall and the continuous outer sidewall. The circumferential used PD fluid channel allows used PD fluid to flow back from the patient, around the series of ribs, and out of the body without contacting, or having very little contact, with the filter membrane.

The filter membrane may be a sterilizing grade or bacteria reduction hydrophilic flat sheet membrane having a pore size of about 0.2 micron, through which the fresh PD fluid flows for further filtration. The flat sheet filter membrane is sized to provide the necessary filtration needed over multiple patient fills of a PD treatment prior to being discarded in one embodiment.

Fresh and further filtered PD fluid flows in one embodiment from the filtered fluid compartment of the body, through an outlet, e.g., hole or aperture, provided in the end of the continuous inner wall opposing a fresh PD fluid entry end of the continuous inner wall. Filtered, fresh PD fluid flows through the outlet and into a transfer set-side port, through the transfer set-side port, through the short tube of the filter set (if provided), and through the patient's transfer set, into the patient's peritoneal cavity. The short tube in one embodiment extends over the transfer set-side port where it is ultrasonically sealed, heat sealed or solvent bonded to the transfer set-side port.

The short tube and the transfer set-side port also receive used PD fluid from the patient after a patient dwell. Used PD fluid flows from the transfer set-side port into the circumferential used PD fluid channel. As mentioned above, the circumferential used PD fluid channel enables used PD fluid to be pulled through the body of the filter housing without contacting and potentially clogging the filter membrane. The circumferential used PD fluid channel also provides a clear path for the used PD fluid, which helps to mitigate against pressure losses due to the filter set. While it is fluidically possible for used PD fluid to flow through the outlet provided in the continuous inner wall and into the filtered fluid compartment of the body, negative pressure is applied only from within the circumferential used PD fluid channel, so there is little incentive for used PD fluid to flow into the filtered fluid compartment. Likewise, while it is fluidically possible for fresh PD fluid to flow into the circumferential used PD fluid channel, the change in direction required for the fresh PD fluid to do so makes such a path more tortuous than simply flowing through the transfer set-side port to the patient. Also, the circumferential used PD fluid channel and the used PD fluid lumen of the dual lumen patient tube are likely full of PD fluid during a patient fill, and the used PD fluid lumen is closed off at the PD machine or cycler, so there is little or no room for fresh PD fluid to enter the circumferential used PD fluid channel.

Used PD fluid removed through the patient's transfer set travels under negative pressure through the filter set via the circumferential used PD fluid channel (thus bypassing the filter membrane), through the used PD fluid lumen of the dual lumen patient line, and back to the machine or cycler. The machine or cycler pumps the used PD fluid under positive pressure to drain. The cycler includes a pressure sensor located along the used PD fluid side of its internal tubing, which measures the negative pressure applied by the PD fluid pump to the used PD fluid during a patient drain. That same pressure sensor may be used during a patient fill to measure the positive pumping pressure, which may be transmitted back through the circumferential used PD fluid channel of the filter set and used PD fluid lumen of the patient line to the pressure sensor. Measuring the positive pumping pressure using the used PD fluid-side pressure sensor is desirable because the measured pressure is of the fresh PD fluid downstream (after filtration) of the filter membrane. The measured pressure accordingly takes into account any pressure drop across the filter membrane, which may more accurately reflect the pressure at which the PD fluid is being delivered to the patient.

As mentioned above, the series of ribs located within the filtered fluid compartment of the body support the flat sheet filter membrane under both (i) positive pressure from above and (ii) from below when the circumferential used PD fluid channel is under negative pressure (which may be transmitted into the filtered fluid compartment via the outlet (hole or aperture) provided in the continuous inner wall). The series of ribs enable the filter membrane (e.g., flat sheet) to be as large as it needs to be to provide a desired filtration capacity. The series of ribs are co-molded with the bottom surface of the body, the continuous inner wall, the continuous outer sidewall, the lumen-side connector and the transfer set-side connector in one embodiment. The flat sheet filter membrane is sealed in place via ultrasonic sealing, heat sealing or solvent bonding to the continuous inner wall and does not extend over the circumferential used PD fluid channel in one embodiment.

The pressurization compartment and the circumferential used PD fluid channel of the body of the filter housing are enclosed by a lid, which may be formed from the same material as the remainder of the body. In this manner, the lid forms the outside of the pressurization compartment into which fresh PD fluid flows before passing through the filter membrane. The lid is ultrasonically sealed, heat sealed or solvent bonded to the continuous inner wall and the continuous outer sidewall of the body so as to fluidically isolate the circumferential used PD fluid channel from the pressurization compartment. A tongue and groove fit may be provided between the lid and either one or both of the continuous inner wall and/or the continuous outer sidewall for sealing.

The lid may be formed with one or more air vent. Each vent is covered on the inside of the lid with a hydrophobic membrane, which may be ultrasonically sealed, heat sealed or solvent bonded to the inside surface of the lid and around the at least one vent opening. The one or more vent and hydrophobic membrane allow air to be vented to atmosphere as the fresh PD fluid is pressurized within the pressurization compartment of the body prior to being filtered through the hydrophilic membrane, which may improve the performance of the membrane in addition to removing air from the filter set. In an embodiment, the lid is provided with one or more protective projection located adjacent to the one or more air vent. The one or more protective projection helps to prevent the one or more air vent from being covered by the patient, a blanket, etc., while the patient sleeps during the PD treatment.

A gasket, such as a silicone or polyvinyl chloride (“PVC”) rubber gasket, may be fitted onto and/or into the fresh and used PD fluid ports of the lumen-side connector of the filter housing. The patient line connector may in turn include fresh and used ports that extend into the fresh and used PD fluid ports of the lumen-side connector. The gasket provides port seals between the mated fresh and used PD fluid ports of the patient line connector and the lumen-side connector.

In light of the disclosure set forth herein, and without limiting the disclosure in any way, in a first aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, a peritoneal dialysis (“PD”) system includes a PD machine: a patient line extending from the PD machine; and a filter set in fluid communication with the patient line, the filter set including a filter membrane positioned and arranged such that fresh PD fluid flows through the filter membrane into a filtered fluid compartment, wherein the filtered fluid compartment includes an outlet to a port, and wherein the port is in fluid communication with a circumferential used PD fluid channel positioned and arranged to carry used PD fluid around the filter membrane without contacting, or limiting contact with, the filter membrane.

In a second aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, the patient line is a dual lumen patient line including a fresh PD fluid lumen and a used PD fluid lumen, the used PD fluid lumen placed in fluid communication with the circumferential used PD fluid channel.

In a third aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, the filter set includes a fresh PD fluid port for fluid communication with the fresh PD fluid lumen and a used PD fluid port for fluid communication with the used PD fluid lumen.

In a fourth aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, the circumferential used PD fluid channel is in fluid communication with the used PD fluid port.

In a fifth aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, the port extends to circumferential used PD fluid channel.

In a sixth aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, the circumferential used PD fluid channel is located between a continuous inner wall and a continuous outer sidewall.

In a seventh aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, the filter set includes a lid sealed to at least one of the continuous inner wall and the continuous outer sidewall.

In an eighth aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, the lid includes at least one vent opening and at least one hydrophobic membrane sealingly covering the at least one vent opening.

In a ninth aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, the continuous inner wall is positioned and arranged to deflect incoming fresh PD fluid over the filter membrane.

In a tenth aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, the PD system includes at least one rib located within the filtered fluid compartment for supporting the filter membrane.

In an eleventh aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, the filter membrane is a flat sheet filter membrane, and wherein the filter set includes a pressurization compartment located on an opposing side of the flat sheet filter membrane from the filtered fluid compartment.

In a twelfth aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, the filter set includes a fresh PD fluid port positioned and arranged to introduce fresh PD fluid to the pressurization compartment.

In a thirteenth aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, the filter set is configured to connect directly to a patient's transfer set, or wherein the filter set includes a flexible tube configured to connect to the patient's transfer set.

In a fourteenth aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, the PD machine includes a pressure sensor positioned and arranged to sense the pressure of fresh PD fluid downstream from the filter membrane during a patient fill.

In a fifteenth aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, the PD machine is configured to close a used PD fluid valve during a patient fill, urging the filtered fresh PD fluid to flow to the port instead of along the circumferential used PD fluid channel.

In a sixteenth aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, the PD machine is configured to close a fresh PD fluid valve during a patient drain, urging used PD fluid to flow along the circumferential used PD fluid channel instead of into the filtered fluid compartment.

In a seventeenth aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, the filter membrane is a sterilizing grade filter membrane or a bacteria reduction filter membrane.

In an eighteenth aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, a filter set includes a filtered fluid compartment including an outlet; a filter membrane positioned and arranged such that fresh PD fluid flows through the filter membrane into the filtered fluid compartment; and a circumferential used PD fluid channel in fluid communication with the outlet, the circumferential used PD fluid channel positioned and arranged to carry used PD fluid around the filter membrane without contacting, or limiting contact with, the filter membrane.

In a nineteenth aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, the filter set includes a port, wherein the outlet is in fluid communication with the port, and wherein the circumferential used PD fluid channel is in fluid communication with the port.

In a twentieth aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, a method is provided for priming a filter set connected to a dual lumen patient line, wherein during treatment a tube is located between the filter set and a patient's transfer set, the method including (i) delivering fresh peritoneal dialysis (“PD”) fluid through a fresh PD fluid lumen of the dual lumen patient line to the filter set: (ii) forcing the fresh PD fluid through a filter membrane of the filter set, so that the fresh PD fluid displaces air towards a used PD fluid lumen of the dual lumen patient line; and pulling used PD fluid from the patient, through the patient's transfer set, through the tube, through a used PD fluid portion of the filter set, and into the used PD fluid lumen of the dual lumen patient line.

In a twenty-first aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, pulling used PD fluid is provided as part of an initial patient drain.

In a twenty-second aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, wherein between forcing the fresh PD fluid through the filter membrane and pulling used PD fluid from the patient, the patient is prompted to connect the tube to the patient's transfer set.

In a twenty-third aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, wherein between forcing the fresh PD fluid through the filter membrane and pulling used PD fluid from the patient, the patient is prompted to open a clamp of the patient's transfer set.

In a twenty-fourth aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, air is primed through at least one vent opening of the filter set while delivering fresh PD fluid through the fresh PD fluid lumen of the dual lumen patient line.

In a twenty-fifth aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, a fresh PD fluid valve is open and a used PD fluid valve is closed while delivering fresh PD fluid through the fresh PD fluid lumen of the dual lumen patient line.

In a twenty-sixth aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, a used PD fluid valve is open while forcing the fresh PD fluid through the filter membrane of the filter set.

In a twenty-seventh aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, a used PD fluid valve is open while pulling used PD fluid from the patient.

In a twenty-eighth aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, the method includes accumulating known volume pump strokes to control a volume pumped to force the fresh PD fluid through the filter membrane.

In a twenty-ninth aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, the method includes sensing a pressure increase to transition from (i) delivering fresh PD fluid through the fresh PD fluid lumen of the dual lumen patient line to the filter set to (ii) forcing the fresh PD fluid through the filter membrane.

In a thirtieth aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, the used PD fluid portion of the filter set includes a circumferential used PD fluid channel.

In a thirty-first aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, the used PD fluid pulled from the patient is residual effluent from a previous treatment left for the purpose of priming the tube.

In a thirty-second aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, a volume of the residual effluent is at least 50 ml.

In a thirty-third aspect of the present disclosure, which may be combined with any other aspect, or portion thereof, any of the features, functionality and alternatives described in connection with any one or more ofFIGS.1to8may be combined with any of the features, functionality and alternatives described in connection with any other ofFIGS.1to8.

In light of the above aspects and the description herein, it is an advantage of the present disclosure to provide a filter set, which operates with a dual lumen patient line.

It is another advantage of the present disclosure to provide a filter set that filters fresh PD fluid and allows used PD fluid to pass without contacting (or having very little contact with) the filter membrane.

It is a further advantage of the present disclosure to provide a filter set having a used PD fluid channel within which used PD fluid may be transported through the filter set cleanly and without obstruction.

It is yet another advantage of the present disclosure to provide a filter set that vents air from the fresh PD fluid before the fluid is filtered by a filter membrane.

Additional features and advantages are described in, and will be apparent from, the following Detailed Description and the Figures. 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 figures and description. Also, any particular embodiment does not have to have all of the advantages listed herein and it is expressly contemplated to claim individual advantageous embodiments separately. Moreover, it should be noted that the language used in the specification has been selected principally for readability and instructional purposes, and not to limit the scope of the inventive subject matter.

DETAILED DESCRIPTION

Referring now to the drawings and in particular toFIG.1, a peritoneal dialysis (“PD”) system10is illustrated. PD system10includes a PD machine or cycler20that pumps fresh PD fluid through a patient line50to a patient P and removes used PD fluid from patient P via patient line50. Patient line50may be reusable or disposable and in either case operates with and fluidly communicates with a filter set100. If patient line50is reusable, the reusable patient line is connected to filter set100at the time of treatment. If patient line50is instead disposable, filter set100is merged into or formed with disposable patient line50in one embodiment. In either configuration, a distal end of filter set100may be connected to the patient's transfer set58(e.g., via a short flexible tube108), which in turn communicates fluidly with the indwelling catheter of patient P.

PD machine or cycler20may include a housing22providing a durable PD fluid pump24that pumps PD fluid through the pump itself without using a disposable component. Examples of durable pumps that may be used for PD fluid pump24include piston pumps, gear pumps and centrifugal pumps. Certain durable pumps, such as piston pumps are inherently accurate, so that machine or cycler20does not require additional volumetric control components. Other durable pumps, such as gear pumps and centrifugal pumps may not be as accurate, such that machine or cycler20provides a volumetric control device such as one or more flowmeter (not illustrated).

Pump24may alternatively be a disposable type PD fluid pump, which includes a pump actuator that actuates a disposable, fluid-contacting pumping component, such as a peristaltic pump tube or a flexible pumping chamber. Examples of disposable PD fluid pumps that may be used for PD fluid pump24include rotary or linear peristaltic pump actuators that actuate tubing, pneumatic pump actuators that actuate cassette sheeting, electromechanical pump actuators that actuate cassette sheeting and platen pump actuators that actuate tubing. It should be appreciated that while a single PD fluid pump24may be used, dedicated fresh and used PD fluid pumps may be used alternatively. Also, single PD fluid pump24may include multiple pumping chambers for more continuous PD fluid flow.

PD machine or cycler20also includes a plurality of valves26a,26b,26m,26nwhich may likewise be flow-through and durable without operating with a disposable component, or be disposable type valves having valve actuators that actuate a disposable, fluid-contacting valve component, such as a tube segment or a cassette-based valve seat. Examples of durable valves that may be used for valves26a,26b,26m,26ninclude flow-through solenoid valves. Such valves may be two-way or three-way valves. Examples of disposable valves that may be used for valves26a,26b,26m,26ninclude solenoid pinch valves that pinch closed flexible tubing, pneumatic valve actuators that actuate cassette sheeting, and electromechanical valve actuators that actuate cassette sheeting.

Machine or cycler20likely includes many valves26ato26n. For ease of illustration, machine or cycler20is shown having a fresh PD fluid valve26athat is controlled to open to allow PD fluid pump24to pump fresh PD fluid under positive pressure through a fresh PD fluid lumen52of dual lumen patient line50to patient P. The valves also include a used PD fluid valve26bthat is controlled to open to allow PD fluid pump24to pull used PD fluid from patient P under negative pressure through a used PD fluid lumen54of dual lumen patient line50. The valves further include one or more supply valve26mthat is controlled to open to allow fresh PD fluid to be pulled from one or more fresh PD fluid source12via one or more solution line14. The valves further include a drain valve26nthat is controlled to allow used PD fluid to be delivered to a house drain or drain container16via a drain line18.

Machine or cycler20in the illustrated embodiment also includes pressure sensors, such as pressure sensors28a,28b. Pressure sensor28ais located just downstream from fresh PD fluid valve26a, while pressure sensor28bis located just upstream from used PD fluid valve26. Pressure sensor28amay accordingly sense the pressure in fresh PD fluid lumen52of dual lumen patient line50even if fresh PD fluid valve26ais closed, while pressure sensor28bmay sense the pressure in used PD fluid lumen54of dual lumen patient line50even if used PD fluid valve26bis closed. Additionally, pressure sensor28ais positioned to sense the pressure of fresh PD fluid upstream from a filter membrane120discussed herein during a patient fill. Pressure sensor28bperhaps more importantly is positioned to sense the pressure of fresh PD fluid downstream (after filtration) from filter membrane120(FIG.4) during a patient fill. The measured pressure via pressure sensor28baccordingly takes into account any pressure drop across filter membrane120(FIG.4), which may more accurately reflect the pressure at which fresh PD fluid is being delivered to patient P.

Pump24and valves26ato26nin the illustrated embodiment are under the automatic control of a control unit40provided by machine or cycler20of system10, while pressure sensors28a,28b(and other sensors) output to control unit40. Control unit40in the illustrated embodiment includes one or more processor42, one or more memory44and a video controller46. Control unit40receives, stores and processes signals or outputs from pressure sensors28a,28b, and other sensors provided by machine or cycler20, such as one or more temperature sensor30and one or more conductivity sensor (not illustrated). Control unit40may use pressure feedback from one or more of pressure sensor28a,28bto control PD fluid pump24to pump dialysis fluid at a desired pressure or within a safe pressure limit (e.g., within 0.21 bar (three psig) of positive pressure to a patient's peritoneal cavity and −0.10 bar (−1.5 psig) of negative pressure from the patient's peritoneal cavity).

Control unit40uses temperature feedback from one or more temperature sensor30for example to control a heater32, such as an inline heater to heat fresh PD fluid to a desired temperature, e.g., body temperature or 37° C. In one embodiment, heater32is used additionally to heat a disinfection fluid, such as fresh PD fluid, to disinfect PD fluid pump24, valves26ato26n, heater32and all reusable fluid lines within machine or cycler20to ready the machine or cycler for a next treatment. The additional filtration discussed herein provides a layer of protection in addition to the heated fluid disinfection to ensure that fresh PD fluid is safe for delivery to patient P.

Video controller46of control unit40interfaces with a user interface48of machine or cycler20, which may include a display screen operating with a touchscreen and/or one or more electromechanical button, such as a membrane switch. User interface48may also include one or more speaker for outputting alarms, alerts and/or voice guidance commands. User interface48may be provided with machine or cycler20as illustrated inFIG.1and/or be a remote user interface operating with control unit40. Control unit40may also include a transceiver (not illustrated) and a wired or wireless connection to a network, e.g., the internet, for sending treatment data to and receiving prescription instructions from a doctor's or clinician's server interfacing with a doctor's or clinician's computer.

Referring toFIGS.1and2, as mentioned above, fresh and used PD fluid lumens52and54of dual lumen patient line50may again be reusable or disposable. In the instance in which dual lumen patient line50is reusable, the lumens terminate with a connector56that connects to a lumen-side connector104of filter set100, which may be sealed to (e.g., ultrasonically sealed, heat sealed or solvent bonded) or molded with a body106of the filter set. Body106as illustrated inFIG.1is connected to a short, e.g., flexible, tube108that extends to a transfer set-side connector110, which connects directly to a mating connector of the patient's transfer set58. Short, e.g., flexible, tube108allows rigid lumen-side connector104and body106to be separated from rigid transfer set-side connector110to aid patient comfort. Forming body106to include transfer set-side connector110, or attaching transfer set-side connector110to body106, and then connecting those rigid structures to the patient's rigid transfer set58may lead to a combined rigid assembly that is uncomfortably tethered to patient P. The space provided by tube108separates body106from transfer set-side connector110so that only the rigid transfer set-side connector is mechanically connected to the patient's transfer set58. In an alternative embodiment, however, transfer-side connector110may be formed with or attached to body106.

Filter set100as packaged may be provided with removable caps (not illustrated and assuming dual lumen patient line50is reusable) on either end of filter set100after the set is sterilized, e.g., via gamma radiation, steam or ethylene oxide, to maintain sterility. To use filter set100, the patient or user removes and discards the caps.

As illustrated inFIG.2, lumen-side connector104may simply include ports, e.g., fresh and used PD fluid ports104fand104u, to which fresh and used PD fluid lumens52and54respectively extend over or into for sealing. If dual lumen patient line50is reusable, patient line connector56may include a releasable clamp that releasably clamps onto fresh and used PD fluid ports104fand104u, e.g., compressing a gasket interacting between patient line connector56and PD fluid ports104fand104u. If dual lumen patient line50is disposable, fresh and used PD fluid lumens52and54may be ultrasonically sealed, heat sealed or solvent bonded to fresh and used PD fluid ports104fand104u, respectively.

As illustrated inFIG.2, in one embodiment fresh and used ports104fand104uof lumen-side connector104are surrounded by a threaded shroud104s, which may make a threaded luer type connection with mating patient line connector56. Here, patient line connector56is configured to thread onto threaded shroud104s, causing the patient line connector56to compress a gasket (not illustrated) and seal mating fresh and used PD fluid ports of patient line connector56to fresh and used PD fluid ports104fand104u, respectively. The gasket may be fitted onto and/or into the fresh and used PD fluid ports104fand104uof the lumen-side connector104. Patient line connector56may include fresh and used ports that extend into the fresh and used PD fluid ports104fand104uof lumen-side connector104. The gasket in one embodiment provides port seals between the mated fresh and used PD fluid ports of patient line connector56and lumen-side connector104.

Referring additionally toFIG.3, lumen-side connector104and body106may be referred to herein as a filter housing102. Filter housing102, transfer set-side connector110, caps (not illustrated), and any other rigid or semi-rigid polymer associated with filter set100may be made of any one or more plastic, such as, polystyrene (“PS”), polycarbonate (“PC”), blends of polycarbonate and acrylonitrile-butadiene-styrene (“PC/ABS”), polyvinyl chloride (“PVC”), polyethylene (“PE”), polypropylene (“PP”), polyesters like polyethylene terephthalate (“PET”), or polyurethane (“PU”). Compressible gasket112may be formed from silicone rubber, PVC or other similar elastomeric material, such as styrene-ethylene-butylene-styrene (“SEBS”) or isoprene. Flexible tube108may be made of PVC or a non-PVC material, such as poly butadiene (“PBD”) or PP.

FIG.3illustrates a top view of body106of filter housing102having its lid1061(FIG.2) and filter membrane120(FIG.4) removed so that a filtered fluid compartment106fof body106is viewable. Fresh PD fluid that has been filtered via filter membrane120(FIG.4) flows into filtered fluid compartment106f.FIGS.1to3further illustrate that fresh and further filtered PD fluid flows in one embodiment from filtered fluid compartment106fof body106, through a transfer set-side port106p, through short tube108of filter set100, through the patient's transfer set58, and into the peritoneal cavity of patient P. Transfer set-side port106pextends from, e.g., is molded with, body106of filter housing102. Short tube108(FIG.1) extends over (or alternatively into) transfer set-side port106p, where it is ultrasonically sealed, heat sealed or solvent bonded to the transfer set-side port106p.

FIGS.3and4illustrate that body106includes a bottom surface106bfrom which a series of support ribs106r(FIGS.3to5) extend. Series of ribs106rextend up from bottom surface106band support flat sheet filter membrane120, both under positive pressure applied above flat sheet filter membrane120and under a negative patient drain pressure applied below flat sheet filter membrane120. Support ribs106rare spaced apart from each other so as to allow fresh, filtered PD fluid to flow in the direction of the arrow (left to right) adjacent to support ribs106rinFIG.4, through filtered fluid compartment106f, to outlet1060. Series of ribs106r, bottom surface106b, continuous inner wall106iand continuous outer sidewall106sof body106are molded as a single piece in one embodiment. Lumen-side connector104and transfer set-side port106pmay also be molded as part of a single piece body106.

A section of filter membrane120is illustrated inFIG.4, so that the series of ribs106rmay also be viewed. It should be appreciated however that filter membrane120is sized in one embodiment to extend across the entire series of ribs106rand seal, e.g., ultrasonically seal, heat seal or solvent bond, to a continuous inner wall106iof body106, e.g., to a continuous raised lip106jformed on continuous inner wall106i. Flat sheet filter membrane120is made in one embodiment of a hydrophilic material that may have a pore size of about 0.2 micron through which fresh PD fluid flows for further filtration. Filter membrane120may be made of, for example, polysulfone or polyethersulfone blended with polyvinylpyrrolidone. Flat sheet filter membrane120is sized (length and width) to provide the necessary filtration needed over multiple patient fills of a PD treatment prior to being discarded after treatment. Flat sheet filter membrane120may be a sterilizing grade filter membrane or a bacteria reduction filter membrane.

FIGS.4and5illustrate that continuous inner wall106iforms an outlet1060, e.g., hole or aperture. Outlet1060is provided at the end of the continuous inner wall opposing a fresh PD fluid entry end of the continuous inner wall. Outlet1060enables fresh, filtered PD fluid to leave filtered fluid compartment106f(bounded by the bottom of filter membrane120, the inside of continuous inner wall106iand the top of bottom surface106bof body106) and flow through transfer set-side port106pto the patient. In an embodiment, outlet1060is molded into continuous inner wall106i.

FIGS.3to5further illustrate that body106includes or forms a continuous outer sidewall106s. Lumen-side connector104and transfer set-side port106pin the illustrated embodiment extend from, e.g., are molded with continuous outer sidewall106s. Continuous outer sidewall106sand continuous inner wall106iare spaced apart from each other so as to form an intermediate circumferential used PD fluid channel106c. Circumferential used PD fluid channel106cmay have a width of one millimeter (“mm”) or more, e.g., about 1 mm, and a depth of 4 mm or more, e.g., about 5 mm. The overall cross-sectional area of circumferential used PD fluid channel106cis large enough to allow used PD fluid, which typically contains patient materials such as fibrin and proteins, which would clog flat sheet filter membrane120over the course of multiple patient drains, to instead flow freely around flat sheet filter membrane120towards used PD fluid lumen54of dual lumen patient line50(FIG.1).

FIG.4perhaps best shows that lid1061is ultrasonically sealed, heat sealed or solvent bonded to both (i) continuous inner wall106iand (ii) continuous outer sidewall106sof body106to complete filter housing102. Prior to sealing lid1061to (i) continuous inner wall106iand (ii) continuous outer sidewall106sof body106, flat sheet filter membrane120is ultrasonically sealed, heat sealed or solvent bonded at its perimeter to continuous raised lip106jformed on continuous inner wall106i. Lid1061is then sealed to an outer portion of continuous inner wall106i, so that both flat sheet filter membrane120and lid1061may be sealed to the continuous inner wall. Sealing lid1061to both (i) continuous inner wall106iand (ii) continuous outer sidewall106sencloses circumferential used PD fluid channel106cfrom the top so that used PD fluid returning from that patient is prevented from spilling over into pressurization compartment106e(FIG.4) located upstream of flat sheet filter membrane120.

In an embodiment, continuous outer sidewall106sincludes or defines a continuous centering sealing rib (not illustrated) that accepts a mating groove (not illustrated) formed along the underside perimeter of lid1061(or vice versa). The fit of the sealing rib to the groove ensures that lid1061is located properly for ultrasonic sealing, heat sealing or solvent bonding to continuous outer sidewall106s. A rib and groove fit may also be made for ultrasonic sealing, heat sealing or solvent bonding between lid1061and continuous inner wall106i. Similarly, the interior of continuous inner wall106imay be provided with a continuous (or beaded) ring of material (not illustrated), which marks the placement position for flat sheet filter membrane120. The ring of material may help to center the placement flat sheet filter membrane120and/or provide additional material to help with the ultrasonic sealing, heat sealing or solvent bonding of filter membrane120to continuous inner wall106i.

The arrows inFIG.3show flow pathways for both fresh PD fluid and used PD fluid through filter set100. The arrows inFIG.4show the flow pathway for fresh PD fluid through filter set100. The arrows inFIG.5show the flow pathway for used PD fluid through filter set100.

FIGS.3and4illustrate that fresh PD fluid enters filter set100through fresh PD fluid port104fin lumen-side connector104and flows towards continuous inner wall106i. Continuous inner wall106ideflects and forces the fresh PD fluid to change direction and flow upward and over continuous inner wall106iinto pressurization compartment106e, which resides over the upstream side of flat sheet filter membrane120. Pressurization compartment106eis sized to distribute the fresh PD fluid across an upstream side of filter membrane120for even distribution of the PD fluid through the porous membrane. Fresh PD fluid is pressurized within pressurization compartment106e(FIG.4). The pressurization forces the fresh PD fluid through the small pours of flat sheet filter membrane120and into a filtered fluid compartment106f(FIG.4) of body106, which is bounded primarily by the underside surface of flat sheet filter membrane120, bottom surface106band continuous inner wall106iof the body. Fresh PD fluid flows along and between series of ribs106rwithin filtered fluid compartment106funtil exiting through outlet1060formed in continuous inner wall106i. The exiting fresh, filtered PD fluid flows through transfer set-side port106pto the patient.

FIGS.3and5illustrate the flow of used PD fluid through filter set100. Here, transfer set-side port106pextends to an inlet of used PD fluid channel106c, which resides between and is defined by continuous inner wall106iand continuous outer sidewall106s. Used PD fluid channel106cin the illustrated embodiment extends from transfer set-side port106pto used PD fluid port104uof lumen-side connector104. Used PD fluid channel106calso extends underneath fresh PD fluid port104f, so that used PD fluid may flow in clockwise and counterclockwise directions through used PD fluid channel106cas illustrated inFIG.3. Used PD fluid port104uis in sealed fluid communication during operation to used PD fluid lumen54of dual lumen patient line50as discussed above.

Used PD fluid channel106cenables used PD fluid to be pulled around body106of filter housing102in two directions without contacting (or very minimally contacting) and potentially clogging filter membrane120. Used PD fluid channel106calso provides a clear, streamlined path for the used PD fluid, which helps to mitigate against pressure losses due to filter set100.

While it is fluidically possible for used PD fluid to flow through outlet1060provided in continuous inner wall106iand into the filtered fluid compartment106fof body106, negative pressure is applied only from within used PD fluid port104uand used PD fluid channel106c, so there is little incentive for used PD fluid to flow into filtered fluid compartment106f. Also, control unit40of PD machine20is configured to close fresh PD fluid valve26aduring a patient drain, urging used PD fluid to flow along the used PD fluid channel106cinstead of into the filtered fluid compartment106f. Likewise, while it is fluidically possible during a patient fill for fresh PD fluid to flow in reverse back up used PD fluid channel106c, the change in direction required makes such a path more tortuous than simply flowing through transfer set-side port106pto patient P. Also, used PD fluid channel106cand used PD fluid lumen54of dual lumen patient tube50are likely full of fresh and/or used PD fluid during a patient fill, and used PD fluid lumen54is closed off via used PD fluid valve26bat PD machine or cycler20, so there is little or no room for fresh PD fluid to enter used PD fluid channel106c.

FIG.6illustrates an alternative lumen-side connector104, which includes a dual lumen connector104dinstead of individual fresh and used PD fluid ports104f. Dual lumen connector104dincludes or defines a fresh PD fluid opening104gand a used PD fluid opening104h, to which a corresponding dual lumen connector56for fresh and used PD fluid lumens52and54respectively extends into for sealing. If dual lumen patient line50is reusable, patient line connector56may compress a gasket interacting between patient line connector56and fresh and used PD fluid openings104g,104h. If dual lumen patient line50is disposable, fresh and used PD fluid lumens52and54may be ultrasonically sealed, heat sealed or solvent bonded to fresh and used PD fluid ports104fand104u, respectively. Lumen-side connector104including a dual lumen connector104dmay also be provided with a threaded shroud104s, which may make a threaded luer type connection with mating patient line connector56. Here, patient line connector56is configured to thread onto threaded shroud104s, causing the patient line connector56to compress a gasket (not illustrated) and seal mating fresh and used PD fluid ports of patient line connector56into fresh and used PD fluid openings104g,104h, respectively. Lumen-side connector104including dual lumen connector104dmay be molded with body106of filter housing102as has been discussed herein.

FIGS.2,7and8further illustrate that lid1061may be provided with vent openings106vthat allow air to be vented from the fresh PD fluid prior to being filtered through filter membrane120. To maintain sterility within body106, one or more hydrophobic membrane122a,122b(FIG.8), etc., is/are ultrasonically sealed, heat sealed or solvent bonded at its/their perimeter(s) to the inside surface of lid106, so as to surround and cover its/their respective vent opening106v. Hydrophobic membranes122a,122b, etc., may be made for example from polytetrafluoroethylene (“PTFE”). While multiple sets of vent openings106vand corresponding hydrophobic membranes122a,122bare shown as being provided with lid1061, only a single set of a vent opening and corresponding hydrophobic membrane may be provided with lid1061.

One or more hydrophobic membrane122a,122b, etc., allows air to be vented to atmosphere as the fresh PD fluid is pressurized within a pressurization compartment106elocated beneath lid1061prior to being filtered through the hydrophilic filter membrane120, which may improve the performance of filter membrane120in addition to removing air from filter set100. In the illustrated embodiment ofFIGS.2,4,7and8, lid1061is provided with one or more protective projection106tlocated adjacent to one or more air vent106v. One or more protective projection106thelps to prevent one or more air vent106vfrom being covered by the patient, a blanket, etc., while the patient sleeps during the PD treatment.

Regarding the priming of filter set100for treatment, fresh PD fluid lumen52of patient line50and filter set100may or may not be primed with fresh PD fluid before short tube108is connected to the patient's transfer set58. If primed, user interface48may audibly, visually or audiovisually prompt patient P to clip patient line connector56and/or filter set100into a clip provided by housing22of PD machine or cycler20. Short tube108may initially be fitted with a cap (not illustrated), so that when patient line connector56or filter set100is clipped to housing22, short tube108hangs off of filter set100and is closed to the environment via the cap. Control unit40then causes PD fluid pump24, with fresh PD fluid valve26aopen and used PD fluid valve26bclosed, to prime fresh PD fluid lumen52with fresh PD fluid up to filter membrane120. Here, air is forced out vent openings106v.

Once fresh PD fluid lumen52is primed fully, pressure sensors28aand28bsense a pressure increase because fresh PD fluid has nowhere to go with used PD fluid valve26bclosed. Upon seeing the pressure increase, with filter membrane120now fully wetted, control unit40then causes used PD fluid valve26bto open, allowing PD fluid pump24to push fresh PD fluid through hydrophilic filter membrane120into filtered fluid compartment106f, which pushes air through the inner compartment, into and through circumferential used PD fluid channel106c, and into a portion of used PD fluid lumen54. Air is accordingly pushed up the used PD fluid lumen54towards system drain. Here, control unit40may be programed to know and actuate a number of known volume strokes of PD fluid pump24needed to adequately prime filtered fluid compartment106f, circumferential used PD fluid channel106c, and a desired portion of used PD fluid lumen54. At this point, body106of filter set100is fully primed. It should be appreciated that filter set100does not have to be clamped to housing22for the above priming of the body106of filter set100to be performed, however, doing so may help to prevent dual lumen patient line50from kinking during such priming.

User interface48of PD machine or cycler20then audibly, visually or audiovisually prompts patient P to remove filter set100from the clip at housing22, to remove the cap from short tube108, to connect short tube108to the patient's transfer set58, and to open the clamp of the patient's transfer set58. Control unit40then in an embodiment, with used PD fluid valve26bopen and fresh PD fluid valve26aopen or closed (likely closed), causes PD fluid pump24to pull used PD fluid from the patient to prime short tube108, here pulling air from the short tube, through circumferential used PD fluid channel106c, up used PD fluid lumen54of dual lumen patient line50, and towards the drain of PD machine or cycler20. Such pulling of used PD fluid may be part of an initial drain of the patient. The amount of used PD fluid removed from the patient is accordingly counted at control unit40(e.g., by accumulating known volume strokes of PD fluid pump24) as part of the treatment's initial drain volume in one embodiment.

If a patient fill is instead the first action to be taken after priming fresh PD fluid lumen52and the body106of filter set100, control unit40may or may not pull effluent from the patient to fully prime short tube108prior to starting the initial patient fill. That is, it is contemplated to allow the small amount of air residing within short tube108to be pushed back to the patient. If however, control unit40does pull an initial amount of effluent from the patient to prime short tube108, control unit40may count whatever amount of effluent is pulled from the patient (e.g., by accumulating known volume strokes of PD fluid pump24) as part of a subsequent initial drain.

In an alternative embodiment, filter set100is not clipped at housing22and short tube108is initially connected to the patient's transfer set58. User interface48here audibly, visually or audiovisually counsels patient P to leave the clamp of the patient's transfer set58closed until instructed to open the clamp. The procedure described above is then performed, wherein here the patient's transfer set clamp is performing the function of the cap at the end of short tube108in the above example. With the patient's transfer set clamp closed, control unit40causes fresh PD fluid to be primed through fresh PD fluid lumen52, body106of filter set, and a portion of used PD fluid lumen54using PD fluid pump24, while sequencing valves26aand26bas discussed above.

User interface48then prompts patient P to open the clamp of the patient's transfer set58and to press a confirm button at user interface48in one embodiment. Upon the confirm button being pressed, control unit40then sequences valves26aand26band actuates pump24as discussed above to pull used PD fluid from the peritoneal cavity of patient P to prime short tube108and circumferential used PD fluid channel106cwith patient effluent. The effluent priming of short tube108may again be part of an initial patient drain.

The pulling of used PD fluid from the patient to prime short tube108assumes that there is used PD fluid to remove from the patient at the start of treatment. This is true in many instances in which the patient is full of used PD fluid at the beginning of treatment from a previous treatment's last fill or from a midday exchange. In some instances, however, the patient is dry at the beginning of treatment. It is contemplated that control unit40of PD machine or cycler20, which may be dedicated at a given time to a single patient, knows the patient's treatment schedule, and thus knows when the patient will begin a next treatment in a dry state with no or very little used PD fluid. It is contemplated here that control unit40, instead of attempting to completely drain the patient in a final drain of a previous treatment, causes a residual amount of effluent to remain within the peritoneal cavity of the patient after treatment. The residual amount may for example be 50 milliliters (“ml”) or more as needed to ensure that the patient's indwelling PD catheter can access the residual effluent. The residual amount should be enough to prime any air at least through the proximal end of short tube108at the junction of filter set100.

The above-described priming procedure is advantageous for a number of reasons. First, a step of having the patient clip patient line connector56into a clip provided by housing22of PD machine or cycler20may be eliminated. Also, the need for patient line connector56to be fitted with a vented cap and/or for housing22of PD machine or cycler20to have a sensor for detecting when fresh PD fluid has reached patient line connector56may be eliminated. Both savings reduce cost and complexity. Second, after treatment, the patient disconnects transfer set-side connector110from the patient's transfer set58and then seals transfer set58with a cap (not illustrated) having a disinfectant, such as iodine, to help prevent peritonitis due for example to patient touch contamination. The cap is then removed and replaced with a new transfer set-side connector110of a new filter set100at the beginning of a next treatment. Residual disinfectant, e.g., residual iodine, remains however. The priming method disclosed herein carries the residual disinfectant away into used PD fluid lumen54of dual lumen patient line50under negative pressure instead of delivering the residual disinfectant to the patient. Doing so may prevent health issues, especially for sensitive patients.

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. It is therefore intended that any or all of such changes and modifications may be covered by the appended claims. For example, dual lumen patient line50could alternatively be a single lumen patient line, wherein filter set100includes check valves, e.g., provided within fresh and used PD fluid ports104f,104uof lumen-side connector104for directing fresh and used PD fluid to desired locations within the set.