Patent Description:
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 triweekly. 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, into a patient's peritoneal chamber via a catheter. The dialysis fluid is in 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 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 spent dialysis 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 or spent dialysis fluid to drain from the peritoneal chamber. The patient then switches fluid communication so that the patient catheter communicates with a bag of fresh dialysis fluid to infuse the fresh dialysis fluid through the catheter and into the patient. The patient disconnects the catheter from the fresh dialysis fluid bag and allows the dialysis fluid to dwell within the peritoneal chamber, 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.

Automated peritoneal dialysis ("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 dialysis fluid and to a fluid drain. APD machines pump fresh dialysis fluid from a dialysis fluid source, through the catheter and into the patient's peritoneal chamber. APD machines also allow for the dialysis 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 or spent dialysate from the peritoneal chamber, though the catheter, and to the 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.

In any of the above modalities using an automated machine, the automated machine operates typically with a disposable set, which is discarded after a single use. Depending upon the complexity of the disposable set, the cost of using one set per day may become significant. Also, daily disposables require space for storage, which can become a nuisance for home owners and businesses. Moreover, daily disposable replacement requires daily setup time and effort by the patient or caregiver at home or at a clinic.

There is also a need for APD devices to be portable so that a patient may bring his or her device on vacation or for work travel.

For each of the above reasons, it is desirable to provide a relatively simple, compact APD machine, which operates a simple and cost effective disposable set.

<CIT> discloses automated peritoneal dialysis (APD) cycler systems and methods. The APD cycler can include a heater tray with load cells configured to measure the weight of fluid contained within a heater bad and/or a drain bag. The load cells can be toggleable between enabled and disabled configurations. The APD cycler can include a pressure-based volume measurement system, which can be used to confirm measurements made by the load cells. In some embodiments, the APD cycler can have algorithms for tracking an estimated patient volume to prevent overfilling the patient.

<CIT> discloses a sensing system for detecting a substance in a dialysate. The system includes a hydrophobic barrier capable of allowing the substance in the dialysate to equilibrate through the barrier to a gas. The system also includes a detector capable of detecting the gas and an interface disposed between the hydrophobic barrier and the detector and configured to allow transport of the gas between the hydrophobic barrier and the detector following a concentration gradient of the gas along the interface.

<CIT> discloses a fluid handling cassette, such as that useable with an automated peritoneal dialysis (APD) cycler device or other infusion apparatus. The fluid handling cassette may include a generally planar body having at least one pump chamber formed as a depression in a first side of the body and a plurality of flowpaths for a fluid that includes a channel. A patient line port may be arranged for connection to a patient line and be in fluid communication with the at least one pump chamber via at least a first one of said flowpaths, and an optional membrane may be attached to the first side of the body over the at least one pump chamber. In one embodiment, the membrane may have a pump chamber portion with an unstressed shape that generally conforms to the depression of the at least one pump chamber in the body and is arranged to be movable for movement of the fluid in a useable space of the at least one pump chamber. One or more spacers may be provided in the at least one pump chamber to prevent the membrane from contacting an inner wall of the at least one pump chamber. The patient line, a drain line, and/or a heater bag line may be positioned to be separately occludable in relation to one or more solution lines that are connectable to the cassette.

<CIT> discloses an automated solution injection-discharge system that is used as an APDS system to supply and discharge a dialysate and a patient's drain. And an automated solution injection-discharge system provides free of contamination and operation mistakes, and can accurately control the injected dialysate volume and the discharged dwell solution volume even when a patient does not maintain a fixed posture while replacing the solution.

The present disclosure relates to an automated peritoneal dialysis ("APD") machine or cycler, which uses a pressure chamber, which may be a rigid, e.g., clamshell, structure that accepts a disposable container, such as a disposable flexible container or bag. A lower or bottom portion of the pressure chamber may be fitted with a heating plate, e.g., a resistive heating plate, which heats the disposable bag during patient dwells and while it is filling and emptying fresh dialysis fluid. The rigid container may be made of plastic, such as, polyvinyl chloride ("PVC"), polyethylene ("PE") or polyurethane ("PU"), or of metal, such as stainless steel or aluminum. The rigid container may be reusable or disposable. The disposable bag is made of a medically safe material such as PVC or a non-PVC material. Where the chamber is a clamshell chamber, a seal such as an o-ring seal may be placed between the clamshell portions to seal same when closed together.

A fluid connection is made between the flexible container or bag and a tube or line extending outside of the pressure chamber. If the chamber is reusable, the chamber may be provided with a bulkhead connector having ports or fittings to which a disposable bag tube or pigtail is connected inside the chamber and to which an external tube or line is connected outside the chamber. In an alternative reusable chamber embodiment, the chamber defines a hole or aperture lined with a compressible material, wherein the tube or line from the flexible bag is extended in a sealed manner through the hole or aperture and is connected in a sterile manner outside the chamber to the supply and drain lines. In a further alternative reusable chamber embodiment, the disposable bag, the line extending from the bag and the solution and drain lines are provided as a premade and presterilized set, wherein the line extending from the bag is fitted, e.g., adhered, to a compressible seal, which is placed between the clamshells of the chamber for sealed operation.

In an embodiment, when the chamber is disposable, the disposable bag, the line extending from the bag, and the solution and drain lines are provided as a premade and presterilized set, wherein the line extending from the bag is permanently sealed to the disposable pressure chamber.

In one embodiment, the single line extending from the disposable flexible container or bag splits into multiple, e.g., five separate lines, each interfacing with a valve, such as an electrically actuated solenoid pinch valve, an electrically actuated motorized pinch valve or a pneumatically actuated valve. Heated, fresh dialysis fluid flows from the disposable bag to the patient through a patient line, while used dialysis fluid flows from the patient through the patient line to the disposable bag. Used dialysis fluid flows from the disposable bag to drain through a drain line. If an external heater is provided, fresh dialysis fluid flows from the disposable bag to a heater through a heater line, where it is heated, and then back to the disposable bag through the heater line. If the pressure chamber is reusable and provided with a heater, then the external heater line is not needed or may be used as a second fill line. Fresh dialysis fluid flows from supply and last fill containers through supply and last fill lines to the disposable bag before heating. Each of the patient line, drain line, heater line (if needed), supply line and last fill line are in fluid communication with the common line extending from the pressure chamber (and possibly extending from the disposable bag through the pressure chamber). Each of the fluid containers, including the flexible container or bag located within the pressure chamber and the fluid lines form a disposable set.

The pressure chamber is placed in pneumatic with a pressurization device, e.g., a motive fluid or air cylinder. A motive fluid or pneumatic valve is located between the cylinder and the pressure chamber. The motive fluid or pneumatic valve allows or disallows the flow of air to the pressure chamber and may be pneumatically or electromechanically actuated. In an embodiment, the motive fluid or pneumatic valve includes a three-way valve with one passage or port in communication with the pressure chamber, one passage or port in communication with a vent and a third passage or port in communication with the cylinder. The cylinder in an embodiment interfaces with a piston having a piston head, which is moved inside of the cylinder by a linear actuator, for example, a lead screw connected to a motor, e.g., a stepper motor. A feedback mechanism, e.g., a potentiometer or motor encoder, may be provided to track the location of the piston head and monitor its movement as it moves back and forth across the cylinder.

It should be appreciated that other types of pumping, alternative to a piston/cylinder may be used. For example, a volumetric pneumatic pump operating with a diaphragm or membrane may also be used to build positive and negative pressure. Another possible pump is a squirrel pump, which can likewise build positive and negative pressure. The alternative pumps may be able to build pressure more quickly.

The system operates using the pressurization device or cylinder to draw fluid from a desired source into the disposable flexible container or bag and then push the fluid out to a desired fluid destination. The desired fluid sources and destinations depend on the stage of treatment. The patient and the heater bag (if provided) may be either a source or a destination, the drain is (typically) only a destination, while the supply bag and last bag are (typically) only a source. In alternative embodiments, one or more supply bag may be used later in treatment as a drain bag to limit disposable waste and cost. Here, the supply and drain bag at different times are a source and a destination.

Each of the drawing-fluid-in and pushing-fluid-out sequences begins with building a pressure within the pressure chamber. Here, all fluid valves are closed and the pneumatic pressure chamber and vent passages or ports are alternated to build a desired starting pressure within pressure chamber (e.g., -<NUM> psig for filling from the patient and +<NUM> psig for pumping to the patient). To build negative pressure within the pressure chamber, the pressure chamber passage or port is closed and the vent port is opened when the piston head is extended within the cylinder to vent the air from the cylinder. Next, the vent port is closed and the pressure chamber port is opened while the piston head is retracted within the cylinder to build a certain amount of negative pressure in the pressure chamber as measured by a pressure sensor, which may be located between the pressurization device or cylinder and the motive fluid or pneumatic valve. The sequence just described is repeated until a desired amount of negative pressure is built within the pressure chamber (e.g., -<NUM> psig). When the desired negative starting pressure is built, a desired liquid source valve is opened to let a desired fluid (e.g., patient effluent, heated fresh fluid, or supply fresh fluid) into the disposable flexible container or bag. The entire sequence just described is then repeated to rebuild the starting motive fluid or pneumatic pressure and to continue filling the disposable bag until there is no change in pressure as measured by the pressure sensor when the fluid valve is opened, indicating that the bag is full. That is, there is no more room within the disposable container or bag to relieve the vacuum.

To build positive pressure within the pressure chamber, the pressure chamber passage or port is closed and the vent port is opened, while the piston head is retracted within the cylinder to allow air to fill the cylinder through the vent. Next, the vent port is closed and the pressure chamber port is opened, while the piston head is extended within the cylinder to build a certain amount of positive pressure in the pressure chamber as measured by the pressure sensor. That sequence is repeated until a desired amount of positive pressure is built within the pressure chamber (e.g., +<NUM> psig). When the desired positive starting pressure is built, a desired liquid destination valve is opened to expel a desired fluid (e.g., heated fresh, fresh supply or patient effluent) from the disposable flexible container or bag. The entire sequence just described is then repeated to rebuild starting motive fluid or pneumatic pressure and to continue expelling fluid from the disposable bag until there is no change in pressure when the fluid valve is opened as measured by the pressure sensor, indicating that the bag is empty. That is, there is no more room in the disposable container or bag to relieve the positive pressure.

It is contemplated during either or both of the negative and positive pressure sequences just described to rebuild the starting pressure and release the rebuilt pressure to the pressure chamber prior to the pressure chamber completely running out of driving pressure. Doing so results in a more continuous fluid flow.

To know how much fluid has been delivered to or from the disposable flexible container or bag, a rough estimate may be provided by a known volume of the disposable bag and assuming the bag is completely filled from empty to full or completely emptied from full to empty. A more precise calculation is performed by adding volumes calculated from the known piston head displacements associated with building and rebuilding the negative and positive pressures, knowing the volumetric dimensions of the pressurization device or cylinder, and assuming each of the fluids pumped to be incompressible.

A third option for volume control is to provide one or more load cell supporting the disposable container. Weight of fluid entering or leaving the container is converted to volume knowing the density of the fluid.

A control unit having one or more processing and memory is provided to control all of the fluid valves, all of the motive fluid or pneumatic valves, or each passage or port of a single three-way motive fluid valve, to read the output of the pressure sensor, to control the heater (provided within the pressure chamber or external to the pressure chamber), to control the linear actuator (e.g., stepper motor coupled to a lead or ball screw), to read the output from the potentiometer or motor encoder and calculate volume delivered, and to interface with a user interface. The user interface may be provided with a touchscreen and/or electromechanical pushbuttons to allow the user or patient to enter parameters for treatment and a display screen for providing information, such as treatment status information.

As discussed in detail herein, the control unit is additionally programmed to handle a situation in which the container becomes completely empty prior to the full use of a positive pressure charge in the chamber. The control unit is also programmed to handle a situation in which the container becomes completely full prior to the full use of a negative pressure charge in the chamber. The control unit is further programmed to handle a situation in which the patient becomes empty during a patient drain prior to the full use of a negative pressure charge in the chamber.

Additionally, a continuous ambulatory peritoneal dialysis ("CAPD") system is disclosed herein, which employs the same type of pumping as the APD system. The CAPD system includes a pressure chamber in which a fresh supply container (e.g., bag) and a drain container (e.g., bag) are located in one embodiment. The piston, cylinder, motor, motor control devices, encoder or potentiometer, valve, filter and associated structure, functionality and alternatives discussed above for the APD system are likewise provided in the CAPD system. Additionally, temperature sensors and possibly an air heater may be provided with the CAPD system (with the APD system also) for increasing accuracy. A control unit is provided to run and receive signals from all above equipment and to perform patient drain and fill sequences in the same manner as described for the APD system. One difference in the CAPD system may be the provision and use of different fresh and drain bags within the chamber.

According to the present invention, there is provided a peritoneal dialysis system according to claim <NUM>.

In a first embodiment of the peritoneal dialysis system of the present invention, the pressure chamber is reusable and is configured to open to accept the flexible container and to close to seal around a common line extending from the flexible container.

In a second embodiment of the peritoneal dialysis system of the present invention, the pressure chamber is disposable and sealed to a common line extending from the flexible container.

In a third embodiment of the peritoneal dialysis system of the present invention, which may also be combined with the first and/or second embodiment, the at least one source line includes at least one supply line connected to a supply of fresh peritoneal dialysis fluid and a patient line for removing used peritoneal dialysis fluid, and the at least one destination line includes the patient line for delivering fresh peritoneal dialysis fluid and a drain line for removing used peritoneal dialysis fluid.

In a fourth embodiment of the peritoneal dialysis system of the present invention, which may also be combined with any one of the first to third embodiments, the pressure chamber includes a fluid heater positioned to heat fluid within the flexible container.

In a fifth embodiment of the peritoneal dialysis system of the present invention, which may also be combined with any one of the first to fourth embodiments, the at least one source line and the at least one destination line include a heater line for extending to a heating container for heating fresh peritoneal dialysis fluid.

In a sixth embodiment of the peritoneal dialysis system of the present invention, which may also be combined with any one of the first to fifth embodiments, the motive fluid pressurization device includes a motive fluid cylinder, a piston located within the motive fluid cylinder, and a linear actuator configured to extend and retract the piston.

In a seventh embodiment of the peritoneal dialysis system of the present invention, which may be combined with the sixth embodiment, the peritoneal dialysis system includes at least one motive fluid valve for opening and closing a pressure chamber passage and a vent passage, and wherein during (i) and (ii) the control unit is configured to perform a negative pressure sequence in which (a) the pressure chamber passage is closed and the vent passage is opened while the piston is extended within the motive fluid cylinder to push motive fluid out of the cylinder, after which (b) the pressure chamber passage is opened and the vent passage is closed while the piston is retracted to pull motive fluid from the pressure chamber into the cylinder to increase the negative pressure within the pressure chamber.

In an eighth embodiment of the peritoneal dialysis system of the present invention, which may be combined with the seventh embodiment, the peritoneal dialysis system includes a fluid valve associated with each of the at least one source lines, and wherein the control unit is configured to open a desired one of the fluid valves when the desired negative motive fluid pressure is reached via the negative pressure sequence.

In a ninth embodiment of the peritoneal dialysis system of the present invention, which may be combined with the eighth embodiment, the fluid valve includes a source line pinch valve.

In a tenth embodiment of the peritoneal dialysis system of the present invention, which may be combined with the sixth embodiment, the peritoneal dialysis system includes at least one motive fluid valve for opening and closing a pressure chamber passage and a vent passage, and wherein during (i) and (ii) the control unit is configured to perform a positive pressure sequence in which (a) the pressure chamber passage is closed and the vent passage is opened while the piston is retracted within the motive fluid cylinder to pull motive fluid into the cylinder, after which (b) the pressure chamber passage is opened and the vent passage is closed while the piston is extended to push motive fluid from cylinder into the pressure chamber to increase the positive pressure within the pressure chamber.

In an eleventh embodiment of the peritoneal dialysis system of the present invention, which may also be combined with any one of the first to tenth embodiments, the peritoneal dialysis system includes a fluid valve associated with each of the at least one destination lines, and wherein the control unit is configured to open a desired one of the fluid valves when the desired positive motive fluid pressure is reached via the positive pressure sequence.

In a twelfth embodiment of the peritoneal dialysis system of the present invention, which may be combined with the eleventh embodiment, the fluid valve includes a destination line pinch valve.

In a thirteenth embodiment of the peritoneal dialysis system of the present invention, which may be combined with the sixth embodiment, the linear actuator includes a ball or lead screw driven by a motor under control of the control unit.

In a fourteenth embodiment of the peritoneal dialysis system of the present invention, which may be combined with the sixth and/or thirteenth embodiment, the peritoneal dialysis system includes a feedback mechanism outputting to the control unit to enable the control unit to determine how far the linear actuator has extended or retracted the piston.

Also described herein but not claimed is a peritoneal dialysis method that includes: enabling a pressurization device to pressurize a pressure cavity to a pressure; opening a fluid valve when the pressure reaches a desired pressure to allow fluid communication with a flexible container located within the pressure cavity; measuring the pressure within the pressure cavity after the fluid valve is opened; and determining that the flexible container is full of fluid or empty of fluid if the pressure within the pressure cavity after the fluid valve is opened becomes or remains at least substantially constant.

In one method, the desired pressure is different for different fluid sources or fluid destinations.

The peritoneal dialysis method may include determining that the flexible container is full or empty if the pressure within the pressure cavity after the fluid valve is opened becomes or remains at least substantially constant prior to pressurization from the pressurization device being exhausted.

It is accordingly an advantage of the present disclosure to provide a relatively volumetrically accurate automated peritoneal dialysis ("APD") cycler.

It is another advantage of the present disclosure to provide an APD cycler that achieves relatively precise pressure control.

It is a further advantage of the present disclosure to provide a relatively quiet APD cycler.

It is still another advantage of the present disclosure to provide an APD cycler in which self-compensates for sensor drift.

It is yet a further advantage of the present disclosure to provide an APD system that may use a same disposable item for both pumping and heating.

It is still a further advantage of the present disclosure to provide an APD system that is able to build motive fluid or pneumatic pressure in a relatively simple manner.

It is yet another advantage of the present disclosure to provide an APD system that employs a relatively low cost disposable set.

Referring now to the drawings and in particular to <FIG> and <FIG>, an automated peritoneal dialysis ("APD") system <NUM> includes and APD machine or cycler <NUM> that operates with a disposable set <NUM>. APD machine or cycler <NUM> includes a housing <NUM> that defines a pressure chamber, which in the illustrated embodiment is a rigid, e.g., clamshell, structure that accepts a disposable container <NUM> of disposable set <NUM>, such as a disposable flexible container or bag. Rigid container <NUM> may be made of plastic, such as, polyvinyl chloride ("PVC"), polyethylene ("PE") or polyurethane ("PU"), or of metal, such as stainless steel or aluminum. Rigid container <NUM> may be reusable or disposable. Disposable bag <NUM> is made of a medically safe material such as PVC or a non-PVC material. Where chamber <NUM> is a clamshell chamber, a seal such as an o-ring seal <NUM> (e.g., silicone) may be placed between the clamshell portions 22a and 22b to seal same when closed together.

As illustrated in <FIG>, a fluid connection is made between flexible container or bag <NUM> and a tube or line <NUM> extending outside of pressure chamber <NUM>. If chamber <NUM> is reusable, the chamber may be provided with a bulkhead connector (not illustrated) having ports or fittings to which a disposable bag tube or pigtail is connected inside the chamber, wherein external tube or line <NUM> is connected to the bulkhead outside the chamber. In an alternative reusable chamber embodiment, chamber <NUM> defines a hole or aperture (not illustrated) lined with a compressible material, wherein tube or line <NUM> from flexible bag <NUM> is extended in a sealed manner through the hole or aperture and is connected in a sterile manner outside the chamber to the supply and drain lines. In a further alternative reusable chamber embodiment, which is illustrated in <FIG>, disposable bag <NUM>, line <NUM> extending from the bag, and the solution and drain lines are provided as a premade and presterilized set <NUM>, wherein line <NUM> extending from the bag is fitted, e.g., adhered to a compressible seal <NUM>, which is placed between correspondingly shaped cutouts 26a and 26b of clamshell halves 22a and 22b, respectively, of chamber <NUM> for sealed operation.

In an embodiment, when chamber <NUM> is disposable, disposable bag <NUM>, line <NUM> extending from the bag, and the solution and drain lines are provided as a premade and presterilized set, wherein line <NUM> extending from bag <NUM> is permanently sealed to disposable pressure chamber <NUM>. In a disposable arrangement, chamber <NUM> will not have the equipment connected to it as described below for the reusable version of chamber <NUM>. The equipment is provided instead on a different housing (not illustrated). The equipment, however, may be at least substantially the same as described herein regardless of whether chamber <NUM> is reusable or disposable.

As illustrated in <FIG>, single line <NUM> extending from the disposable flexible container or bag <NUM> splits into five separate lines <NUM>, <NUM>, <NUM>, <NUM> and <NUM>, each interfacing with a respective valve <NUM>, <NUM>, <NUM>, <NUM> and <NUM>, such as an electrically actuated solenoid pinch valve, an electrically actuated motorized pinch valve or a pneumatically actuated valve. Heated, fresh dialysis fluid flows from disposable container <NUM> to the patient through patient line <NUM>, while used dialysis fluid flows from the patient through patient line <NUM> to disposable bag <NUM>. Used dialysis fluid flows from disposable bag <NUM> to drain through drain line <NUM>. If an external heater is provided, fresh dialysis fluid flows from disposable bag <NUM> to the external heater through heater line <NUM> to a heater bag (illustrated below), where it is heated, and then back to the disposable bag through heater line <NUM>. If pressure chamber <NUM> is reusable and provided with a heater <NUM> discussed in more detail below, then external heater line <NUM> is not needed or is provided as an additional fresh dialysis fluid line. Fresh dialysis fluid flows from supply and last fill containers (illustrated below) through supply line <NUM> and last fill line <NUM> to disposable container <NUM> before heating. As illustrated, each of patient line <NUM>, drain line <NUM>, heater line <NUM> (if needed), supply line <NUM> and last fill line <NUM> are in fluid communication with common line <NUM> extending from pressure chamber <NUM> (and possibly extending from disposable container <NUM> through the pressure chamber). Each of the fluid containers, including flexible container or bag <NUM> located within pressure chamber <NUM> and fluid lines <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> form disposable set <NUM>.

In <FIG>, lower or bottom portion 22b of pressure chamber <NUM> is fitted with a heater plate <NUM>, e.g., a resistive heating plate, as part of heater <NUM>, which heats the fluid within disposable bag <NUM> while it is filling and emptying fresh dialysis fluid, and for subsequent fills, during patient dwell periods in which dialysis fluid resides in the patient's peritoneal cavity to perform treatment. Heater <NUM> in the illustrated embodiment includes resistive heating elements <NUM> through which current is passed to heat the elements and thus heater plate <NUM> and the fluid within container <NUM>. Heater plate <NUM> in the illustrated embodiment is angled or tilted to force air towards an upper portion of container <NUM>, while common line <NUM> extending through pressure chamber <NUM> extends in the other direction to connect to the lower end of container <NUM>.

<FIG> and <FIG> illustrate that system <NUM> includes a control unit <NUM>, which in the illustrated embodiment is provided with reusable pressure chamber <NUM>, e.g., on the top of upper clamshell portion 22a. If pressure chamber <NUM> is disposable, control unit <NUM> is provided on an alternative APD machine housing (not illustrated). Control unit <NUM> is further alternatively provided as a wireless user interface, such as a tablet or smartphone. In any case, as illustrated in <FIG>, control unit <NUM> may include one or more processor <NUM>, one or more memory <NUM>, and a video controller <NUM> interfacing with a user interface <NUM>, which may include a display screen operating with a touchscreen and/or one or more electromechanical button, such as a membrane switch. User interface <NUM> may also include one or more speaker for outputting alarms, alerts and/or voice guidance commands. Control unit <NUM> may also include a transceiver 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.

<FIG> and <FIG> also illustrate that upper clamshell portion 22a and lower clamshell portion 22b may be connected via a hinge <NUM>, which may be a living hinge or include separate hinges. Although not illustrated, one or more releasable locking mechanism may be provided to compress o-ring seal <NUM> when upper clamshell portion 22a is closed onto lower clamshell portion 22b.

<FIG> and <FIG> also illustrate that pressure chamber <NUM> is placed in motive fluid or pneumatic communication with a pressurization assembly <NUM>. Pressurization assembly <NUM> in the illustrated embodiment includes a motor <NUM>, such as a stepper motor, having an output shaft <NUM>, a feedback mechanism <NUM> such as an encoder, and mounting holes <NUM> for mounting motor to lower clamshell portion 22b. Output shaft <NUM> is coupled via a coupler <NUM> to a lead or ball screw <NUM> located behind a piston as described below. Coupler <NUM> may be a flexible couple configured to inhibit or reduce backlash, which increases positional accuracy. Lead or ball screw <NUM> may be provided with ball bearings to further prevent backlash and improve positional accuracy.

Lead or ball screw <NUM> is held between bearings 84a and 84b, which are mounted to lower clamshell portion 22b. A carriage <NUM> is threadingly engaged to lead or ball screw <NUM> and translates back and forth along lead or ball screw <NUM> depending on which direction it is turned by motor <NUM>. Carriage <NUM> extends outwardly from lead or ball screw <NUM> to form one end of a piston <NUM> having a piston head <NUM>, which is slidingly sealed within a motive fluid or air cylinder <NUM>. In an embodiment, motor <NUM>, lead or ball screw <NUM> and bearings 84a and 84b are metal, e.g., stainless steel, steel, aluminum and combinations and alloys thereof, while carriage <NUM>, piston <NUM> and piston head <NUM> may be any of the metals listed or plastic, such as PVC, PE, PU, polycarbonate and combinations thereof. Each of those components is reusable in one embodiment.

<FIG> illustrates a state in which carriage <NUM>, piston <NUM> and piston head <NUM> are in a fully retracted state relative to cylinder <NUM>. If motor <NUM> is turned such that carriage <NUM> is translated to the right, piston <NUM> and piston head <NUM> will likewise extend within cylinder <NUM> to the right. Because piston head <NUM> is airtightly but slidingly sealed within cylinder <NUM>, extending head <NUM> within cylinder <NUM> pushes a motive fluid, such as air, out of the cylinder via fitting <NUM>. Fitting <NUM> in the illustrated embodiment is a hose barb fitting onto which a flexible motive fluid or pneumatic tube <NUM> is sealed. Flexible tube <NUM> may be made of any suitable material, such as PVC, PE, PU or silicone. The flexibility of tube <NUM> allows upper clamshell portion 22a to open relative to lower clamshell portion 22b.

<FIG> illustrates that the other end of motive fluid or pneumatic tube <NUM> is connected to a motive fluid or pneumatic valve <NUM> via a fitting <NUM>, such as a hose barb onto which the flexible tube is sealed. Valve <NUM> is mounted to upper clamshell portion 22a and is located as illustrated between motive fluid or air cylinder <NUM> and pressure chamber <NUM>. Motive fluid or pneumatic valve <NUM> allows or disallows the flow of motive fluid or air to pressure chamber <NUM> and may be pneumatically or electromechanically actuated. In the illustrated an embodiment, valve <NUM> includes a three-way valve with one passage or port 64a in motive fluid or pneumatic communication with pressure chamber <NUM>, a second passage or port 64b in motive fluid or pneumatic communication with a reusable vent <NUM>, such as a hydrophobic vent for filtering incoming air, and a third passage or port 64c in motive fluid or pneumatic communication with cylinder <NUM>. In the illustrated embodiment, passage or port 64a is placed in motive fluid or pneumatic communication with pressure chamber <NUM> via line <NUM> (metal or plastic) fittingly connected to upper clamshell portion 22a.

<FIG> further illustrates that a pressure sensor <NUM> is located so as to sense a motive fluid or air pressure created via piston <NUM>, piston head <NUM> and cylinder <NUM>. Pressure sensor <NUM> in the illustrated embodiment is provided with valve <NUM> at a location between passage or port 64c and cylinder <NUM>. Pressure sensor <NUM> may alternatively be located so as to operate with motive fluid or pneumatic tube <NUM> or to extend directly from cylinder <NUM>.

As illustrated in <FIG> and <FIG>, control unit <NUM> having one or more processing <NUM> and memory <NUM> is provided to control (as indicated by dotted control lines) all of fluid valves <NUM> to <NUM>, at least one motive fluid or pneumatic valve <NUM> (e.g., each passage or port 64a to 64c of single three-way valve <NUM>), to read the output of pressure sensor <NUM>, to control heater <NUM> (provided within pressure chamber <NUM> or external to the pressure chamber), to control the linear actuator (e.g., stepper motor <NUM> coupled to lead or ball screw <NUM>), to read the output from encoder <NUM> (or potentiometer as illustrated below) and calculate volume delivered, and to interface with user interface <NUM>, which may be provided with a touchscreen and/or electromechanical pushbuttons to allow the user or patient to enter parameters for treatment and a display screen for providing information, such as treatment status information. Control unit <NUM> stores one or more program, and the processing to execute the one or more program, to operate each of the sequences discussed below.

<FIG> illustrates that patient line <NUM> extends to a transfer set <NUM> for patient P. Disposable set <NUM> includes patient line <NUM> and a drain container or bag <NUM> connected to drain line <NUM> (drain line <NUM> alternatively extends to a house drain, e.g., a toilet or tub). Disposable set <NUM> further includes heater line <NUM> extending to heater container or bag <NUM> (heater <NUM> is alternatively provided within chamber <NUM>), supply line <NUM> extending to supply container or bag <NUM> and last fill line <NUM> extending to last fill container or bag <NUM>. System <NUM> operates using the pressurization assembly <NUM> including motive fluid or air cylinder <NUM> to draw fluid from a desired source into disposable flexible container or bag <NUM> and then push the fluid out to a desired fluid destination. The desired fluid sources and destinations depend on the stage of treatment. Patient P and heater bag <NUM> (if provided) may be either a source or a destination, drain bag <NUM> is (typically) only a destination, while supply bag <NUM> and last bag <NUM> are (typically) only sources. In alternative embodiments, one or more supply bag <NUM> may be used alternatively as a drain bag to limit disposable waste and cost. Here, the supply and drain bag at different times is a source and a destination.

In the methodology of system <NUM>, each of the drawing-fluid-in and pushing-fluid-out sequences begins with building pressure (negative or positive) within pressure chamber <NUM>. In the pressure building sequences, all fluid valves <NUM> to <NUM> are closed, while pressure chamber passage or port 64a and vent passage or port 64b are alternated (with cylinder passage or port 64c open) to build a desired starting pressure within pressure chamber <NUM>. Desired starting pressures may include, for example, -<NUM> psig for removing fluid from patient P, +<NUM> psig for pumping fluid to patient P, and higher pressures, e.g., -<NUM> to -<NUM> psig for more quickly removing fluid from supply bag <NUM> and last fill bag <NUM> and, e.g., +<NUM> to +<NUM> psig for more quickly pumping fluid to drain bag <NUM> and heater bag <NUM> (if provided). It is accordingly contemplated that pressure chamber <NUM> and disposable container <NUM> be configured to withstand a pressure range, for example, -10psig to +<NUM> psig.

<FIG> and <FIG> illustrate, via a piston arrow (dotted) and motive fluid arrow (dashed), that in a first step to build negative pressure within the pressure chamber <NUM>, pressure chamber passage or port 64a is closed, while vent passage or port 64b and cylinder passage or port 64c are opened. Piston <NUM> and head <NUM> are extended (from <FIG>) within cylinder <NUM> to vent air from the cylinder via vent <NUM>. All fluid valves <NUM> to <NUM> are closed.

<FIG> illustrates, via the piston arrow and motive fluid arrow, that next, vent passage or port 64a is closed, while pressure chamber passage or port 64b and cylinder passage or port 64c are opened. Piston <NUM> and head <NUM> are retracted within cylinder <NUM> to build a certain amount of negative pressure in pressure chamber <NUM> as measured by pressure sensor <NUM>, which here is located along motive fluid or pneumatic tube <NUM> between cylinder <NUM> and motive fluid or pneumatic valve <NUM>. All fluid valves <NUM> to <NUM> remain closed.

The sequence just described between <FIG> and <FIG> versus <FIG> is repeated until a desired amount of negative pressure is built within the pressure chamber <NUM> (e.g., -<NUM> psig) as measured by pressure sensor <NUM>. When the desired negative starting pressure is built, a desired liquid source valve is opened to let a desired fluid (e.g., patient effluent via fluid valve <NUM>, heated fresh fluid via heater valve <NUM>, or supply fresh fluid via valves <NUM> or <NUM>) into disposable flexible container or bag <NUM>. The negative pressure in chamber <NUM> is relieved via the expansion of container or bag <NUM>. The fluid valve is closed when pressure sensor <NUM>, with passages or ports 64a and 64c opened and vent passage or port 64b closed, detects that the pressure has returned to <NUM> psig.

The entire container <NUM> filling sequence just described, including the sequence described between <FIG> and <FIG> versus <FIG>, and the fluid valve opening and closing of the previous paragraph, is then repeated to rebuild the starting negative pressure and to continue filling disposable container or bag <NUM>, until there is no change in pressure as measured by pressure sensor <NUM> when the desired fluid valve is opened, indicating that container or bag <NUM> is full. That is, there is no more room within container or bag <NUM> to relieve the vacuum.

Once container or bag <NUM> is full, the fluid is delivered to a desired destination. <FIG> illustrates via the piston arrow and motive fluid arrow, that in a first step to build positive pressure within pressure chamber <NUM>, pressure chamber passage or port 64a is closed, while pneumatic vent passage or port 64b and cylinder passage or port 64c are opened. Piston <NUM> and head <NUM> are retracted within cylinder <NUM> to allow air to fill the cylinder through vent <NUM>. All fluid valves <NUM> to <NUM> are closed.

Next as illustrated in <FIG> via the piston arrow and motive fluid arrow, vent port 64b is closed, while pressure chamber port 64a and cylinder passage or port 64c are opened. Piston <NUM> and head <NUM> are extended within cylinder <NUM> to build a certain amount of positive pressure in pressure chamber <NUM> as measured by pressure sensor <NUM>.

The sequence just described between <FIG> and <FIG> is repeated until a desired amount of positive pressure is built within pressure chamber <NUM> (e.g., +<NUM> psig). When the desired positive starting pressure is built, a desired liquid destination valve is opened to expel a desired fluid (e.g., heated fresh via patient valve <NUM> to patient P, fresh supply to heater bag <NUM> via valve <NUM> or patient effluent to drain bag <NUM> via valve <NUM>) from disposable flexible container or bag <NUM>.

In one embodiment, the positive pressure in chamber <NUM> is relieved via the contraction of container or bag <NUM>. The fluid valve is closed when pressure sensor <NUM>, with passages or ports 64a and 64c opened and vent passage or port 64b closed, detects that the pressure has returned to <NUM> psig. The entire container <NUM> pump-out sequence, including the sequence described between <FIG> and <FIG> and the fluid valve opening and closing just described, is then repeated to rebuild the starting positive pressure and to continue pumping from disposable container or bag <NUM>, until there is no change in pressure as measured by pressure sensor <NUM> when the desired fluid valve is opened, indicating that container or bag <NUM> is full. That is, there is no more room within container or bag <NUM> to relieve the positive pressure.

In another embodiment, system <NUM> does not allow the pump-out pressure to fall to zero before rebuilding positive pressure within pressure chamber <NUM>. This enables the pumping of fluid out of container or bag <NUM> to be performed on a more continuous basis. Here, as illustrated by the piston, motive fluid, and medical fluid arrows in <FIG>, fluid valve <NUM>, for example, is open so that fresh dialysis fluid flows to patient P. Valve <NUM> is placed in a state having pressure chamber passage or port 64a closed and vent and cylinder passages or ports 64b and 64c opened. Piston <NUM> and head <NUM> are retracted within cylinder <NUM> to draw motive fluid or air into the cylinder.

In a next step illustrated in <FIG> with only piston and medical fluid arrows, all passageways or ports 64a to 64c of valve <NUM> are closed, while valve <NUM>, for example, is open so that fresh dialysis fluid continues to flow to patient P. Piston <NUM> and head <NUM> are extended within cylinder <NUM> to pressurize air within the cylinder to the desired starting pressure as measured by pressure sensor <NUM>, e.g., to <NUM> psig for pumping fresh dialysis fluid to patient P.

In a next step illustrated in <FIG> by the motive fluid and medical fluid arrows, valve <NUM>, for example, remains open so that fresh dialysis fluid continues to flow to patient P. Valve <NUM> is placed in a state having pressure chamber vent passage 64b closed and chamber and cylinder passages or ports 64a and 64c opened. Piston <NUM> and head <NUM> are maintained in the position achieved in <FIG> to rebuild the starting pressure. The rebuilt pressure, e.g., <NUM> psig, is then allowed to repressurize chamber <NUM> to continue to pump out dialysis fluid, but not above the set starting pressure.

The sequence in <FIG> is repeated to create at least substantially continuous flow until pressure no longer drops within chamber <NUM>, indicating that container or bag <NUM> is completely empty. That is, when piston <NUM> no longer needs to be moved to maintain a rebuilt pressure as sensed by pressure sensor <NUM>, control unit <NUM> of system <NUM> determines that container or bag <NUM> is completely empty. It should be appreciated that rebuilding pressure prior to exhausting an existing driving pressure in chamber <NUM> may be performed in a similar manner using negative pressure to, for example, remove effluent from patient P in more continuous manner.

It should be also appreciated that in the illustrated embodiment, because the same pressure sensor <NUM> is used to measure pressure while both filling and emptying flexible container <NUM>, drift in the pressure sensor over time is cancelled out. System <NUM> is accordingly robust from at least this standpoint.

To know how much fluid has been delivered to or from the disposable flexible container or bag, a rough estimate is provided by knowing and storing into memory the volume of the disposable bag and assuming the bag is completely filled from empty to full or completely emptied from full to empty. Alternatively, it may be estimated fairly accurately how much air is removed to container or bag <NUM> during priming of disposable set <NUM> and assumed that the air remains in the disposable set over the course of treatment. Here, the known volume of container or bag <NUM> less the estimated quantity of air is taken in memory <NUM> of control unit <NUM> as the volume of fluid completely filled from empty to full or completely emptied from full to empty. If a heater bag <NUM> is provided, system <NUM> may instead prime air initially in set <NUM> to the heater bag.

A more precise calculation is performed by adding volumes calculated from the sensed piston head displacements associated with building and rebuilding the negative and positive pressures, i.e., while passageways or ports 64a and 64c of valve <NUM> are open, storing the volumetric dimensions of cylinder <NUM>, and assuming each of the fluids pumped to and from container or bag <NUM> to be incompressible. As discussed above, motor <NUM> may be provided with an encoder <NUM>, which may be an incremental or absolute encoder. The encoder monitors the rotational position of the shaft of motor <NUM> and the numbers of turns it makes. That data in combination with the known translational distance per rotation of lead or ball screw <NUM> provides a precise distance that carriage <NUM>, piston <NUM> and piston head <NUM> have moved. That distance multiplied by the area of, e.g., circular, cylinder <NUM> provides a precise displacement volume. Adding each displacement volume over a completed fill of container or bag <NUM> or a completed emptying of container or bag <NUM> results in a total volume of fluid filled or emptied.

<FIG> illustrates an alternative embodiment in which a potentiometer <NUM> is used instead of encoder <NUM>. Potentiometer <NUM> outputs to control unit <NUM> as illustrated and directly measures the distance that carriage <NUM>, piston <NUM> and piston head <NUM> have moved without having to know and rely on the geometry of lead or ball screw <NUM>. A less expensive lead screw <NUM> may be used accordingly. The distance moved multiplied by the area of, e.g., circular, cylinder <NUM> again provides a precise displacement volume.

It is possible for system <NUM> of the present disclosure to encounter a situation in which chamber <NUM> is fully charged with pressure, e.g., to +<NUM> psig, but container <NUM> is almost empty so the full +<NUM> psig is not used to empty bag <NUM>, e.g., the bag becomes completely empty at +<NUM> psig. In such case, control unit <NUM> sees that the output from pressure sensor <NUM> has stopped falling and now remains constant at +<NUM> psig. Control unit <NUM> from such detection determines that bag <NUM> is empty. Control unit <NUM> notes the position of piston head <NUM> at +<NUM> psig and then causes piston head <NUM> to extend within cylinder <NUM> a distance until the pressure increases to +<NUM> psig at which point the movement of piston head <NUM> is stopped and control unit <NUM> notes this second position of piston head <NUM>. The difference in the two positions moving from +<NUM> psig to +<NUM> psig is assumed to result in the same volume, knowing the cross-sectional area of cylinder <NUM>, as the volume of fluid delivered from +<NUM> psig to +<NUM> psig with piston head <NUM> held fixed. If there is not enough room in cylinder <NUM> to complete the pressure rebuild, it is contemplated for control unit <NUM> to cause: (i) cylinder <NUM> to vent via vent <NUM>, (ii) piston head <NUM> to retract fully within cylinder <NUM>, (iii) piston head <NUM> to be extended to a first noted position to achieve the original ending pressure, e.g., +<NUM> psig, and (iv) piston head <NUM> to be further extended to a second noted position to achieve the original starting pressure, e.g., +<NUM> psig. The difference between the two noted positions is assumed to result in the same volume, knowing the cross-sectional area of cylinder <NUM>, as the volume of fluid delivered from +<NUM> psig to +<NUM> psig with piston head held fixed.

Alternatively or additionally (e.g., for confirmation) a look-up table may be provided, e.g., developed empirically as a part of the original software of system <NUM>, or over time as system <NUM> is used, which correlates a particular pressure drop with a particular volume of fluid delivered. Further alternatively or additionally (e.g., for confirmation) an equation may be provided, e.g., developed empirically as a part of the original software of system <NUM>, or over time as system <NUM> is used, which calculates a volume of fluid delivered knowing a particular pressure drop until bag <NUM> becomes empty.

In System <NUM>, the same situation can occur in the negative pressure case in which bag <NUM> becomes completely full before fully relieving the negative pressure in the chamber. For example, suppose bag <NUM> becomes full at -<NUM> psig after starting from -<NUM> psig. In such case, control unit <NUM> sees that the output from pressure sensor <NUM> has stopped falling and now remains constant at -<NUM> psig. Control unit <NUM> from such detection determines that either (i) bag <NUM> is full or (ii) the patient is empty such that the current pressure can no longer remove fluid from the patient. Control unit <NUM> notes the position of piston head <NUM> at -<NUM> psig and then causes piston head <NUM> to withdraw within cylinder <NUM> a distance until the negative pressure increases to -<NUM> psig at which point the movement of piston head <NUM> is stopped and control unit <NUM> notes this second position of piston head <NUM>. The difference in the two positions moving from -<NUM> psig to -<NUM> psig is assumed to result in the same volume, knowing the cross-sectional area of cylinder <NUM>, as the volume of fluid received in bag <NUM> from -<NUM> psig to -<NUM> psig with piston head <NUM> held fixed. If there is not enough room in cylinder <NUM> to complete the pressure rebuild, it is contemplated for control unit <NUM> to cause: (i) cylinder <NUM> to vent via vent <NUM>, (ii) piston head <NUM> to extend fully within cylinder <NUM>, (iii) piston head <NUM> to be retracted to a first noted position to achieve the original ending pressure, e.g., -<NUM> psig, and (iv) piston head <NUM> to be further retracted to a second noted position to achieve the original starting negative pressure, e.g., -<NUM> psig. The difference between the two noted positions is assumed to result in the same volume, knowing the cross-sectional area of cylinder <NUM>, as the volume of fluid delivered from -<NUM> psig to -<NUM> psig with piston head held fixed.

Alternatively or additionally (e.g., for confirmation) a look-up table may be provided, e.g., developed empirically as a part of the original software of system <NUM>, or over time as system <NUM> is used, which correlates a particular pressure drop with a particular volume of fluid received in bag <NUM>. Further alternatively or additionally (e.g., for confirmation) an equation may be provided, e.g., developed empirically as a part of the original software of system <NUM>, or over time as system <NUM> is used, which calculates a volume of fluid received in bag <NUM> knowing a particular pressure drop until bag <NUM> becomes empty.

It is contemplated that control unit <NUM> be programmed to detect when the patient may be empty or close to empty when the negative pressure is sensed to remain constant as opposed to bag <NUM> becoming full. For instance, control unit <NUM> may be programmed to determine that a patient empty state is reached, as opposed to a bag being full state, after a certain volume of effluent has been removed from the patient, e.g., approaching an expected patient drain amount. Alternatively or additionally (e.g., for confirmation), control unit <NUM> may be programmed to determine that a patient empty state is reached, as opposed to a bag being full state, when the pressure reading stops changing and remains constant too soon after valve <NUM> is opened for a bag full state to possibly have been reached, e.g., within less than half of an expected amount of time.

In any case, when control unit <NUM> determines a patient empty (or near empty) state, it is contemplated that after determining the volume removed from the patient after the pressure stops changing as discussed above, control unit <NUM> with valve <NUM> closed causes piston head to retract to build negative pressure to a safe level, e.g., -<NUM> psig, and to then open valve ports 64a and 64c to see if any additional effluent can be removed at this higher pressure. If the patient is completely empty, the raised negative pressure will not change. If the patient is close to empty, the raised negative pressure will be relieved until the patient becomes fully empty and the pressure stops changing. Control unit <NUM> then determines the additional volume removed from the patient and adds it to a total patient drain volume for the present fill, dwell and drain cycle.

Alternatively or additionally (e.g., for volume confirmation), systems <NUM> and <NUM> (discussed below) may include one or more load cell (not illustrated) that is located within lower clamshell portion 22b (<FIG>), so that heater plate <NUM> rests on the one or more load cell. The one or more load cell outputs to control unit <NUM>, which knowing the weight of plate <NUM> and bag <NUM> itself, may determine the total weight of a complete fill or empty of container or bag <NUM> by measuring the incremental weight due to the fluid filled or emptied.

Referring now to <FIG>, an alternative continuous ambulatory peritoneal dialysis system <NUM> is provided using an alternative pressure chamber housing <NUM>, which in the illustrated embodiment is a rigid, e.g., clamshell, structure that accepts a fresh fluid disposable container <NUM> and a drain fluid disposable container <NUM>, e.g., disposable flexible bags, of an alternative disposable set <NUM>. Rigid container <NUM> may be made of plastic, such as, polyvinyl chloride ("PVC"), polyethylene ("PE") or polyurethane ("PU"), or of metal, such as stainless steel or aluminum. Rigid container <NUM> may be reusable or disposable. Disposable bags <NUM> and <NUM> may be made of a medically safe material such as PVC or a non-PVC material. Where chamber <NUM> is a clamshell chamber, a seal such as an o-ring seal (e.g., silicone) may be placed between the clamshell portions of chamber <NUM> to seal same when closed together, e.g., in a manner the same as or similar to that illustrated and described in connection with <FIG>.

The clamshell portions may also seal about bag lines 206a and 206b leading from bags <NUM> and <NUM>, respectively, in a manner the same as or similar to that illustrated and described in connection with <FIG>. Bag lines 206a and 206b extend to a common patient line <NUM>, which includes a connector at its distal end for connecting to a patient's transfer set. As illustrated in <FIG>, bag lines 206a and 206b are positioned so as to operate with pinch valves <NUM> and <NUM>, respectively, e.g., motorized pinch valves. Pinch valves <NUM> and <NUM> are alternatively manual clamps.

CAPD system <NUM> includes motive fluid or pneumatic valve <NUM> (e.g., three-way valve having ports 64a to 64c, pressure sensor <NUM>, air filter <NUM>, piston <NUM> (and associated motor, motor control devices, and encoder or potentiometer), piston head <NUM>, piston cylinder <NUM> and pneumatic tube or line <NUM> including all of the structure, functionality and alternatives discussed above for system <NUM>. CAPD system <NUM> and APD system <NUM> may additionally include one or more temperature sensor 146a and/or 146b outputting to control unit <NUM>. In the illustrated embodiment, temperature sensor 146a is positioned and arranged to sense the temperature of air within chamber <NUM>, while temperature sensor 146b is positioned and arranged to sense the temperature of air within pneumatic tube or line <NUM>. CAPD system <NUM> and APD system <NUM> may additionally include an inline air heater <NUM> under control of control unit <NUM>. The readout from temperature sensor 146a and/or 146b may be used as feedback by control unit <NUM> to actuate inline air heater <NUM> to try to match the air temperature inside pneumatic tube or line <NUM> with the air temperature within chamber <NUM>. In an embodiment, control unit <NUM> attempts to maintain the temperature within chamber <NUM> and pneumatic tube or line <NUM> to be at body temperature or <NUM>.

In an embodiment, control unit <NUM> of CAPD system <NUM> is programmed to allow the user to specify either a patient drain then fill (if initially full) or a patient fill, dwell, then drain (if initially empty). A patient drain is performed by pneumatically pulling effluent from the patient into drain fluid disposable container <NUM> according to any of the patient drain embodiments discussed above in connection with system <NUM>, including (i) when drain container becomes full before an entire negative charge within chamber <NUM> is exhausted and (ii) when the patient becomes fully drained before an entire negative charge within chamber <NUM> is exhausted. A patient fill is performed by pushing fresh dialysis fluid from supply bag <NUM> to the patient according to any of the patient fill embodiments discussed above in connection with system <NUM>, including when supply bag <NUM> is fully emptied before an entire positive charge within chamber <NUM> is exhausted. It is contemplated that CAPD system <NUM> may reduce patient fill and drain times by half versus gravity filling.

Control unit <NUM> monitors total fill and drain volumes over a specified period, e.g., twenty-four hours, calculates and reports to the patient an ultrafiltration ("UF") value for the specified period. Control unit <NUM> for system <NUM> may also include a transceiver and a wired or wireless connection to a network, e.g., the internet, for sending treatment data to, including daily UF data, and receiving prescription instructions from a doctor's or clinician's server interfacing with a doctor's or clinician's computer.

Claim 1:
A peritoneal dialysis system (<NUM>) comprising:
a pressure chamber (<NUM>);
a disposable set (<NUM>) including a flexible container (<NUM>) located within the pressure chamber, at least one source line (<NUM>, <NUM>, <NUM>) and at least one destination line (<NUM>, <NUM>);
a motive fluid pressurization device (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>);
a motive fluid pressure sensor (<NUM>); and
a control unit (<NUM>) in operable communication with the motive fluid pressurization device (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) and the motive fluid pressure sensor (<NUM>), the control unit configured to (i) pressurize the pressure chamber (<NUM>) on the outside of the flexible container (<NUM>) to a desired positive or negative motive fluid pressure used to push fluid out of the flexible container through one of the at least one destination line (<NUM>, <NUM>) or pull fluid into the flexible container through one of the at least one source line (<NUM>, <NUM>, <NUM>), respectively, and (ii) repeat (i) until a motive fluid pressure read by the motive fluid pressure sensor becomes or remains at least substantially constant when it is attempted to push fluid out of the flexible container or pull fluid into the flexible container, indicating that the flexible container is empty or full, respectively.