Abstract:
Peritoneal dialysis is performed by circulating peritoneal dialysis solution through a peritoneal cavity by conveying peritoneal dialysis solution through an inlet branch into the peritoneal cavity and by withdrawing peritoneal dialysis solution through an outlet branch from the peritoneal cavity. Peritoneal dialysis solution in the outlet branch is conveyed along a first side of a porous membrane while conveying a regeneration solution containing at least one regenerating agent along a second side of the porous membrane. The membrane is configured to transport the regenerating agent into the peritoneal dialysis solution while transporting waste from the peritoneal dialysis solution into the regeneration solution, thereby creating a regenerated peritoneal dialysis solution. The regenerated peritoneal dialysis solution is circulated through the inlet branch into the peritoneal cavity.

Description:
RELATED APPLICATION 
     This application is a continuation-in-part of U.S. Provisional Patent Application Serial No. 60/121,733, filed Feb. 26, 1999, and entitled “Flow-Through Peritoneal Dialysis Systems and Methods with On-Line Dialysis Solution Regeneration,” which is incorporated herein by reference. 
    
    
     1. Field of the Invention 
     The invention relates to systems and methods for performing peritoneal dialysis. 
     BACKGROUND OF THE INVENTION 
     Peritoneal Dialysis (PD) periodically infuses sterile aqueous solution into the peritoneal cavity. This solution is called peritoneal dialysis solution, or dialysate. Diffusion and osmosis exchanges take place between the solution and the bloodstream across the natural body membranes. These exchanges remove the waste products that the kidneys normally excrete. The waste products typically consist of solutes like sodium and chloride ions, and the other compounds normally excreted through the kidneys like urea, creatinine, and water. The diffusion of water across the peritoneal membrane during dialysis is called ultrafiltration. 
     Conventional peritoneal dialysis solutions include dextrose in concentrations sufficient to generate the necessary osmotic pressure to remove water from the patient through ultrafiltration. 
     Continuous Ambulatory Peritoneal Dialysis (CAPD) is a popular form of PD. A patient performs CAPD manually about four times a day. During CAPD, the patient drains spent peritoneal dialysis solution from his/her peritoneal cavity. The patient then infuses fresh peritoneal dialysis solution into his/her peritoneal cavity. This drain and fill procedure usually takes about 1 hour. 
     Automated Peritoneal Dialysis (APD) is another popular form of PD. APD uses a machine, called a cycler, to automatically infuse, dwell, and drain peritoneal dialysis solution to and from the patient&#39;s peritoneal cavity. APD is particularly attractive to a PD patient, because it can be performed at night while the patient is asleep. This frees the patient from the day-to-day demands of CAPD during his/her waking and working hours. 
     APD offers flexibility and quality of life enhancements to a person requiring dialysis. APD can free the patient from the fatigue and inconvenience that the day to day practice of CAPD represents to some individuals. APD can give back to the patient his or her waking and working hours free of the need to conduct dialysis exchanges. 
     Still, CAPD and APD as practiced today require the use of bagged solutions, which are expensive and difficult to handle and connect. Bagged solutions also do not permit the use of bicarbonate buffering solutions due to sterilization issues. The complexity and size of past machines and associated disposables for various APD modalities have dampened widespread patient acceptance of APD as an alternative to manual peritoneal dialysis methods. 
     SUMMARY OF THE INVENTION 
     The invention provides systems and methods for conducting peritoneal dialysis. 
     One aspect of the invention provides a system for conducting peritoneal dialysis. The system comprises a pumping assembly to circulate peritoneal dialysis solution through a peritoneal cavity to perform peritoneal dialysis. The pumping assembly includes an inlet branch to convey peritoneal dialysis solution into the peritoneal cavity and an outlet branch to withdraw peritoneal dialysis solution from the peritoneal cavity. The system also includes a regeneration assembly coupled in-line between the inlet and outlet branches. The regeneration assembly includes a source of a regeneration solution that carries at least one agent for regenerating spent peritoneal dialysis solution. The regenerating agent can include, e.g., an electrolyte and a buffering agent. The regeneration assembly also includes a porous membrane having a first side and a second side. The pumping assembly circulates peritoneal dialysis solution along the first side of the porous membrane from the outlet branch to the inlet branch. The regeneration solution is circulated along the second side of the porous membrane. The porous membrane is configured to transport waste from spent peritoneal dialysis solution into the regeneration solution and to transport the regenerating agent from the regeneration solution into spent peritoneal dialysis solution. The transport can occur, e.g., by diffusion, convection, or both. The regeneration assembly thereby operates to create from peritoneal dialysis solution in the outlet branch, a regenerated dialysis solution for conveyance through the inlet branch into the peritoneal cavity. 
     The source of regeneration solution can draw water from a source of water, which can comprise, e.g., running tap water. In one embodiment, the source of regeneration solution includes a device to treat water drawn from the source of water, as well as a device to mix the at least one regenerating agent with water drawn from the source of water. 
     The source of regeneration solution can alternatively include a container holding a volume of water in which the at least one regenerating agent is mixed. In one embodiment, the source of regeneration solution includes a first container holding a volume of water and a second container that holds the at least one regenerating agent. The second container is located within the first container. The second container includes a wall material that, when contacted by water, transports the at least one regenerating agent into the water, thereby forming the regeneration solution. 
     In one embodiment, the regeneration assembly includes a device to heat the regeneration solution before circulation along the second side of the porous membrane. 
     In one embodiment, the inlet branch communicates with a first access device providing access to the peritoneal cavity, and the outlet branch communicates a second access device providing access to the peritoneal cavity independent of the access provided by the first device. In this arrangement, the pumping assembly can include a controller that withdraws peritoneal dialysis solution through the second access device into the regeneration assembly while conveying regenerated peritoneal dialysis solution from the regeneration device into the peritoneal cavity through the first access device. At least one of the first and second access devices can comprise, e.g., a subcutaneous access port. 
     In one embodiment, the inlet and outlet branches jointly communicate with a single access device that provides common access to the peritoneal cavity. In this arrangement, the pumping assembly can include a controller operating in a draw mode, to withdraw peritoneal dialysis solution from the peritoneal cavity through the single access device into the regeneration assembly, and a return mode, to convey regenerated peritoneal dialysis solution into the peritoneal cavity through the single access device. The single access device comprises, e.g., a subcutaneous access port. 
     In one embodiment, the regeneration assembly includes a fluid balancing module to maintain a volumetric balance between waste and regenerating agent transported by the porous membrane. 
     In one embodiment, the regeneration assembly includes an ultrafiltration module to selectively transport a preselected greater volume of waste than regenerating agent. 
     In one embodiment, the pumping assembly can accommodate circulation of a cleaning or disinfecting agent through the inlet and outlet branches, bypassing the peritoneal cavity. The regeneration assembly can also accommodate circulation of a cleaning or disinfecting agent along the first and second sides of the porous membrane. 
     Another aspect of the invention provides a method for conducting peritoneal dialysis. The method (i) circulates peritoneal dialysis solution through a peritoneal cavity to perform peritoneal dialysis by conveying peritoneal dialysis solution through an inlet branch into the peritoneal cavity and by withdrawing peritoneal dialysis solution through an outlet branch from the peritoneal cavity. During at least a portion of step (i), the method(ii) conveys peritoneal dialysis solution in the outlet branch along a first side of a porous membrane while conveying a regeneration solution containing at least one regenerating agent along a second side of the porous membrane. The membrane is configured to transport the regenerating agent into the peritoneal dialysis solution while transporting waste from the peritoneal dialysis solution into the regeneration solution, thereby creating a regenerated peritoneal dialysis solution. During at least a portion of step (i), the method (iii) circulates the regenerated peritoneal dialysis solution through the inlet branch into the peritoneal cavity. 
     The steps (ii), and (iii) can be performed simultaneously or sequentially. 
     During step (ii), a prescribed volumetric balance can be maintained between waste and regenerating agent transported by the porous membrane to achieve fluid balancing. Also during step (ii), a preselected greater volume of waste than regenerating agent cen be selectively transported by the porous membrane to achieve ultrafiltration. $$ 
     Other features and advantages of the inventions are set forth in the following specification and attached drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic view of a system for conducting flow-through peritoneal dialysis, showing a dual access with the peritoneal cavity; 
     FIG. 2 is a schematic view of a system for conducting flow-through peritoneal dialysis, showing a single access with the peritoneal cavity; 
     FIG. 3 is a side section view of a subcutaneous peritoneal cavity access device, showing the associated valve assembly in a closed condition; 
     FIG. 4 is a side section view of the subcutaneous peritoneal cavity access device shown in FIG. 3, showing the associated valve assembly in a closed condition; 
     FIG. 5 is a schematic view of a system like that shown in FIG. 1, in which the regeneration solution is supplied in a batch process; 
     FIG. 6 is a schematic view of a system like that shown in FIG. 1, in which the regeneration solution is supplied in a continuous process; and 
     FIG. 7 is a schematic view of the regeneration solution module like that shown in FIG. 1, which also includes fluid balancing and fluid removal capabilities. 
    
    
     The invention may be embodied in several forms without departing from its spirit or essential characteristics. The scope of the invention is defined in the appended claims, rather than in the specific description preceding them. All embodiments that fall within the meaning and range of equivalency of the claims are therefore intended to be embraced by the claims. 
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     I. System Overview 
     FIG. 1 shows a system  10  for conducting flow-through peritoneal dialysis, which embodies the features of the invention. The system  10  includes a peritoneal dialysis solution flow set  12  that is connected to an access device  18 . The access device  18  establishes communication between the system  10  and the peritoneal cavity  20  of a patient. 
     The system  10  also includes a cycler  14 . The cycler  14  interacts with the flow set  12 , to pump peritoneal dialysis solution into and out of the patient&#39;s peritoneal cavity  20 . 
     The system  10  also includes a controller  16 . The controller  16  governs the interaction between the set  12  and the cycler  14 , to perform a selected flow-through peritoneal dialysis procedure. 
     The flow set  12  includes an in-line membrane device  22 . The membrane device  22  includes a housing  24 , which encloses a semipermeable membrane  26 . The membrane  26  can encloses a semipermeable membrane  26 . The membrane  26  can have different geometries. In the illustrated embodiment, the membrane  26  comprises a bundle of hollow fibers, through which peritoneal dialysis fluid drawn from the peritoneal cavity  20  of the patient flows. 
     The membrane  26  compartmentalizes the chamber  24  into a patient side  28  and a regeneration side  30 . In the illustrated embodiment, the patient side  28  comprises the bores of the bundled hollow fibers, and the regeneration side  30  comprises the interior space surrounding the bundled hollow fibers. An inlet port  32  and an outlet port  34  convey dialysis solution into and out of the patient side  28  of the chamber  24  (i.e., into and out of the bores of the hollow fibers). An inlet port  36  and outlet port  38  convey regeneration solution into and out of the regeneration side  30  of chamber  24 . 
     The set  12  circulates peritoneal dialysis solution, transported from the patient&#39;s peritoneal cavity  20 , along the patient side  28  of the membrane  26 . The set  12  also circulates a regeneration solution containing electrolytes and/or bicarbonate buffering materials along the regeneration side  30  of the membrane  26 . The cycler  14  creates and supplies the regeneration solution, as will be described in detail later. 
     The pores of the membrane  26  are sized to pass, by diffusion and convection, waste and uremic toxins from the patient side  28  to the regeneration side  30 . The pores of the membrane  26  are also sized to pass, by the same transport mechanisms, electrolytes and bicarbonate buffering materials from the regeneration side  30  to the patient side  28 . 
     The in-line membrane device  22  thereby makes possible the continuous, on-line regeneration of peritoneal dialysis solution circulated in the set  12 . 
     The cycler  14  includes a fluid source  40 . In the embodiment shown in FIG. 1, the fluid source  40  comprises a water treatment module  42 , a regeneration solution module  44 , and a waste module  46 . 
     The water treatment module  42  receives water from a household water supply and processes the water, using e.,g., filtration, or absorption, or filtration and absorption, or reverse osmosis (with or without pre-filtration and/or absorption), or de-ionization (with or without pre-filtration and/or absorption), or reverse osmosis and de-ionization (with or without pre-filtration and/or absorption). By such processing, the water treatment module  42  creates water substantially free of pyrogens and microorganisms. 
     The regeneration solution module  44  receives processed water from the water treatment module  42 . The regeneration solution module  44  mixes electrolytes and/or buffering agents with the processed water to create the regeneration solution. The module  44  verifies the make up of the solution and heats the solution to body temperature, for delivery to the regeneration side  30  of the membrane device  22 . 
     The waste module  46  directs system drain and waste water from the regeneration side  30  of the membrane device  22  to a drain  56  or other selected receptacle. 
     The fluid source  40  of the cycler  14  obviates the need for bagged solutions, except for initially priming the set  12  prior to conducting a flow-through peritoneal dialysis procedure. The fluid source  40  makes possible the continuous, on-line regeneration of peritoneal dialysis solution, which the set  12  circulates from and into the patient&#39;s peritoneal cavity  20 . 
     The processing controller  16  can comprise a stand-alone micro-processor controlled module or a mechanically and /or electrically controlled module linked to the cycler  14 . In the illustrated embodiment, however, the cycler  14  and controller  16  are located within a common housing  48 . The housing  48  presents a compact footprint, suited for operation upon a table top or other relatively small surface normally found in the home. 
     In the illustrated embodiment, the controller  16  also includes an interactive user interface  50 . The interface So comprises some form of a display  52 , which can be analog or digital, and some form of a patient input device  54 , such as knobs, dials, switches, keyboard or a touch screen on the display  52 . The interface  50  can e.g., present on the display  52  the current status of the cycler  14 , or prompt the user to input commands and information, or receive data from the various sensors and other components of the cycler  14 , record the data in memory, or control the operation of the active components of the cycler  14  (such as valves, pumps, heaters, etc.), or alert the patient to abnormal or failure conditions in the cycler  14  with alarms or other indicators, or any or all of these functions. Additionally, the interface  50  can be linked, e.g., by modem, to a central monitoring station or a central data collection site. 
     The set  12  can be a single use, disposable item, or it can, with cleaning and disinfection, be reusable. This aspect with be described in greater detail later. 
     In use, the cycler  14  draws peritoneal dialysis solution from the patient&#39;s peritoneal cavity  20 , regenerates the dialysis solution, and returns the regenerated dialysis solution to the patient&#39;s peritoneal cavity  20 , in a continuous or semi-continuous, extracoporeal path. The constant or semi-constant flow of peritoneal dialysis solution through the peritoneal cavity  20  provides sustained, high clearance of waste and toxins, which are conveyed to the drain  56 . The on-line regeneration of dialysis solution provides lower costs and requires less manipulation and set up than systems relying upon the connection and disconnection of bagged solutions. 
     II. Flow-Through Peritoneal Dialysis Modalities 
     The system  10  is particularly well suited to perform flow-through peritoneal dialysis (FTPD) . For this reason, the use of the system  10  to perform various modalities of FTPD will be described in detail. 
     (A) Dual Access to the Peritoneal Cavity 
     In the embodiment shown in FIG. 1, the access device  18  provides dual access, having a dedicated inlet  58  for conveying solution into the peritoneal cavity  20  and a dedicated outlet  60  for conveying solution from the peritoneal cavity  20 . Dual access provides continuous flow into and out of the peritoneal cavity  20 . 
     Dual access can be provided, e.g., by a two indwelling catheters, a dual lumen, indwelling catheter, or two subcutaneous access devices. Further details of a preferred subcutaneous access device will be provided later. 
     In this arrangement, the set  12  includes a flexible inlet tube  62  with a connector  64  that connects to the peritoneal cavity outlet  60 . The inlet tube  62  also is also connected to the inlet port  32  on the patient side  28  of the membrane device  22 , to convey dialysis solution across the patient side  28  of the membrane  26 . 
     The cycler  14  includes an inlet pump  66 . In the illustrated embodiment, the inlet pump  66  comprises a peristaltic pump. The pump  66  includes rotating rollers  68  driven by a motor, e.g., a brushless D.C. motor. The rollers  68 , in succession, press against and pinch the flexible inlet tube  62  against a pump race  70 , thereby urging liquid flow from the peritoneal cavity  20  through the inlet tube  62  across the patient side  28  of the membrane device  22  in known peristaltic fashion. Of course, other types of noninvasive pumps can be used, provided that pump speed can be monitored and controlled. 
     The set  12  further includes an outlet tube  72 , which is coupled to the outlet port  34  of the patient side  28  of membrane device  22 . The outlet tube  72  conveys regenerated dialysis solution from the patient side  28  of the membrane  26 . The outlet tube  72  carries a connector  74  that couples to the peritoneal cavity inlet  58 , to further convey the regenerated dialysis solution into the patient&#39;s peritoneal cavity  20 . 
     The cycler  14  also includes two noninvasive pressure sensors  76  and  78 . The sensors  76  and  78  monitor fluid pressure, respectively, in the inlet tube  62  and the outlet tube  72 . The controller  16  analyzes the sensed pressures and regulates the inlet pump  66  to maintain the pressure in the outlet tube  72  within a predetermined safe range. The controller  16  also terminates operation of the inlet pump  66  if sensed pressure in the inlet tube  62  falls outside a predetermined range. 
     The cycler  14  further includes a noninvasive fluid intake valve  80 . The controller  16  closes the intake valve  80 , to prevent the supply of dialysis solution to the peritoneal cavity  20 , should a predetermined alarm condition arise. 
     (B) Single Access to the Peritoneal Cavity 
     In the embodiment shown in FIG. 2, the access device  18  provides a single access through a single indwelling catheter or a single subcutaneous access device. The single access arrangement provides semi-continuous flow of dialysis solution into and out of the peritoneal cavity  20  in a succession of draw modes and return modes. The quick cycling of draw and return modes provides virtually the same results as a continuous flow-through procedure, as just described. 
     In this arrangement, the set  12  includes a connector tube  82  with a connector  84  that connects to the single access device  18 . The connector tube  82  includes a y-connector  86 , to which the inlet tube  62  and the outlet tube  72  are connected. The inlet tube  62  is connected to the inlet port  32  of the membrane device  22 . The outlet tube  72  is coupled to the outlet port  34  of the membrane device  22 . 
     In this arrangement, the outlet tube  72  includes an in-line, non-vented reservoir  88 . The reservoir  88  receives regenerated dialysis solution from the membrane device  22 . A sensor  90  monitors fluid pressure in the reservoir  88 , which increases as solution fills the reservoir  88  and decreases as solution exits the reservoir  88 . 
     The cycler  14  includes in the outlet tube  72  the same, previously described noninvasive fluid intake valve  80 . In the arrangement, the cycler  14  also includes a noninvasive fluid removal valve  92  in the inlet tube  62 . 
     The controller  16  toggles the fluid intake valve  80  and the fluid removal valve  92  between opposing opened and closed states, to affect successive fluid draw and fluid return modes. 
     In the fluid draw mode, the fluid removal valve  92  is opened and the fluid intake valve  80  is closed. The inlet pump  66  conveys dialysis solution through the inlet tube  62  from the peritoneal cavity  20  into the membrane device  22 . The outlet tube  72  conveys regenerated dialysis solution from the membrane device  22  to the reservoir  88 . 
     When a predetermined pressure condition exists in the reservoir  88 , as sensed by the senor  90 , the controller  16  switches to the fluid return mode. The inlet pump  66  is stopped. The fluid intake valve  80  is opened, and the fluid removal valve  92  is closed. Regenerated dialysis solution flows by pressure from the reservoir  88  through the outlet tube  72  and into the peritoneal cavity  20 . The return mode terminates when the pressure condition in the reservoir  88 , as sensed by the sensor  90 , drops below a predetermined threshold. 
     The controller  16  then switches to another fluid draw mode. The controller  16  cycles between successive fluid draw and return modes until the desired objectives of a given therapy session are met. 
     (C) Subcutaneous Access Device 
     The system  10  can include one or more subcutaneous access devices  94 , which are specially designed to accommodate high flow and frequent cannulation. A dual access arrangement requires two devices  94 , whereas a single access arrangement requires but a single device  94 . 
     In the dual access arrangement, the connectors  64  and  74  of the inlet tube  62  and the outlet tube  72  comprise inlet and outlet cannulas. The cannulas are greater than about  18  gauge, and thereby capable of sustaining high flow rates to and from the patient&#39;s peritoneal cavity  20 . In a single access arrangement, the connector  84  of the connector tube  82  comprises a single cannula. 
     The cannula connectors, in turn, are inserted into the access devices  94 . Each device  94  is implanted subcutaneously for repeated access by the cannula, which is passed into the device  94  percutaneously through the skin. 
     The access device  94  can be constructed in various ways. In the illustrated embodiment (see FIGS.  3  and  4 ), the device  94  is generally constructed in the manner disclosed in pending U.S. patent application Ser. No. 08/724,948, filed Nov. 20, 1996, and entitled “Subcutaneously Implanted Cannula and Method for Arterial Access.” 
     As shown in FIGS. 3 and 4, the device  94  includes a housing  210  carrying a valve assembly  212 . The valve assembly  212  comprises fixed valve member  214  and a shuttle valve member  216 . 
     The shuttle valve member  216  is movable relative to the fixed valve member  214  between opened and closed positions. In the opened position (shown in FIG.  4 ), the shuttle valve member  216  is spaced away from the fixed valve member  214 , forming a valve passage  218  between them. In the closed position (shown in FIG.  3 ), the shuttle valve member  216  contacts or is in a close adjacent relationship with the fixed valve member  214 , which closes the valve passage  218 . A spring  220  normally biases the shuttle valve member  216  toward the closed position, shown in FIG.  3 . 
     The device  94  also includes an access passage  222 . The access passage  222  opens into the interior of the housing  210  through a port  224 . The access passage  222  generally extends perpendicular to the valve passage  218 . 
     A flexible tube  226  is secured to the access passage  222  inside the housing  210 . The tube  226  extends from the access passage  222  and bends to pass through the valve passage  218 . The tube  226  extends beyond the housing  210  and, when implanted with the device  94 , communicates with the peritoneal cavity  20 . 
     As FIG. 3 shows, the normally closed position of the valve assembly  212  pinches the tube  226  between the fixed and movable valve members  214  and  216 , thereby blocking fluid flow through the tube  226 . 
     An array of balls  228  rest in a circular channel  230  formed in the access passage  222  near the access port  224 . The circular channel  230  allows movement of the balls  228  along a formed cam surface  232  radially of and axially along the access passage  222 . Carried with the circular channel  230 , the balls  228  rest against the shuttle valve member  216 . 
     The spring  220 , which biases the shuttle valve member  216  toward the closed position, also normally urges the balls  228  along the cam surface  232  out into mutually facing contact within the access passage  222  near the access port  224 . The surface contact of the balls  228  in this position occurs generally along the center line of the access passage  222  and port  224 . 
     A cannula connector C, when passed through the access port  224  and toward the access passage  222 , breaks the surface contact between the balls  228 . Continued passage of the cannula connector C between the separated balls  228  and into the access passage  222  causes the balls to move along the cam surface  232  outward of and axially along the passage  222  away from the access port  224 . Movement of the balls  228  in this path presses against the shuttle valve member  216 . 
     The cannula connector C transmits through the balls  228  a counter force to the biasing spring  220 , which overcomes the spring bias. As a result, the shuttle valve member  216  is moved away from the fixed valve member  214 , opening the valve passage  218 , as FIG. 4 shows. The tube  226 , no longer pinched, opens. Fluid flow through the cannula connector C is directed through the tube  226  to and from the peritoneal cavity  20 . 
     Movement of the cannula connector C out of the access passage  222  relieves the counter force against the balls  228 . With the cannula connector C free of the balls  228 , the now unopposed biasing force of the spring  220  returns the balls  228  along the cam surface  232  axially toward the access port  224  and radially back into the access passage  222 . At the same time, the shuttle valve member  216  is urged toward the closed position, closing the tube  226 . 
     III. Supply of Regeneration Solution 
     (A) Batch Process 
     The fluid source  40  can provide regeneration solution in a batch process. In this arrangement (see FIG.  5 ), the fluid source  40  includes a flexible or rigid source container  96 . The source container  96  contains an aliquot of purified water from the water treatment module  42  or another source. The aliquot is sufficient to supply regeneration solution for an entire therapy session. 
     Appropriate electrolytes are added to the purified water in the source container  96 . This combination forms the regeneration solution. The appropriate electrolytes can be bicarbonate buffer based or lactate buffer based. 
     In one embodiment, the appropriate concentration of electrolytes are enclosed within the source container  96  in a smaller bag  98 . The bag  98  is made of semi-permeable material. When purified water is introduced into the source container  96 , the electrolytes diffuse through the smaller bag  98  into the water, making a homogeneous solution. In another embodiment, the concentrated electrolytes are introduced in powdered or liquid form to the purified water in the source container  96 . 
     The regeneration fluid module  44  draws solution from the source container  96 . The module  44  verifies the contents of the solution for safety and heats the solution to body temperature. The module  44  then circulates the regeneration solution to the regeneration side  30  of the membrane device  22 , through an inlet line  114  to the port  36 , using a pump  100 . 
     If desired, the regeneration solution can be passed through a sterilizing filter  102  prior to entering the regeneration side  30  of the membrane device  22 . 
     A fluid return line  104  communicating with the outlet port  38  on the regeneration side  30  of the membrane device  22  can communicate, via the waste module  46 , directly with the drain  56 . Alternatively, the fluid return line  104  can be connected to a waste bag  106 , which can itself comprise the source container from the previous treatment session. 
     Still alternatively, the fluid return line  104  can be connected to the source container  96 , forming a re-circulation loop  128 . The returning used fluid can be separated from the fresh fluid in the source container  96  by a temperature boundary layer, or by a membrane in the source container  96 . 
     (B) Continuous Flow Process 
     The fluid source  40  can also provide regeneration solution in a continuous flow process. In this arrangement (see FIG.  6 ), the water treatment module  42  supplies purified water to the regeneration solution module  44  on a continuous or on-demand basis. 
     In this arrangement, the regeneration solution module  44  dispenses the appropriate concentrated electrolyte solution from a source  130  to the purified water to make regeneration solution. As before stated, the appropriate electrolytes can be bicarbonate buffer based or lactate buffer based. 
     The regeneration solution module  44  verifies the content of the solution for safety and heats the solution to body temperature. The regeneration solution module  44  supplies the solution continuously through the regeneration side  30  of the membrane device  22 , through the inlet line  114  to the inlet port  36 , using the pump  100 . As before stated, the regeneration solution module  44  can pass the solution through the sterilizing filter  102  prior to entering the regeneration side  30  of the membrane device  22 . 
     In this arrangement, as in the batch arrangement, the fluid return line  104 , coupled to the outlet port  38  of the regeneration side  30  of the membrane device  22 , can be connected to a waste container  106  or directly to a drain  56  through the waste module  46 . 
     IV. Fluid Balancing and Removal 
     During peritoneal dialysis, it is desirable to maintain, at least partially, a normal physiologic fluid and electrolytic balance in the patient. Usually, an ultrafiltration function is also performed during peritoneal dialysis, by which the overall fluid level of the individual is decreased. 
     For these purposes, the cycler  14  can include a fluid balancing module  108  (see FIG.  7 ). In the illustrated embodiment, the fluid balancing module  108  includes non-invasive fluid flow rate sensing devices  110  and  112  in the inlet line  114  and the return line  104  of the regeneration side  30  of the membrane device  22 . 
     The fluid balancing module  108  also includes a flow restrictor  116  located in the return line  104 . The flow restrictor  116  comprising e.g., a stepper-driven pressure clamp, which pinches the outlet line  104  to control its flow resistance. 
     The controller  16  monitors the flow rates sensed by the sensing devices  110  and  112 . The controller  16  operates the pump  100  and/or the flow restrictor  116  to maintain a zero differential in flow rates at the inlet and outlet of the regeneration side  30  of the membrane device  22 . In this way, fluid balance is maintained as the dialysis solution is regenerated. 
     Other forms of fluid balancing can be used. For example, an outlet pump can be placed in the return line  104 , which can be operated in tandem with the inlet pump  100  to achieve fluid balance, without use of in-line pressure sensing. Other flow control devices in the inlet line  114  and return line  104  can be used to achieve a fluid balance between fluid entering and leaving the regeneration side  30  of the membrane device. 
     There are alternative ways to achieve fluid balancing in a continuous flow arrangement, like that shown in FIG.  7 . For example, an outlet pump can be placed in the return line  104 , which can be operated in tandem with the inlet pump  100  to achieve fluid balance, without use of in-line pressure sensing. Other flow control devices in the inlet line  114  and return line  104  can be used to achieve a fluid balance between fluid entering and leaving the regeneration side  30  of the membrane device  24 . 
     Fluid balancing can also be achieved in a batch flow arrangement, like that shown in FIG.  5 . For example, a pump may be placed in-line in the re-circulation loop  128 . The pump is operated in tandem with the pump  100  to achieve fluid balance in the source container  98 . Alternatively, without a re-circulation loop  128 , a pump can be placed in-line in the return line  104  in the same manner shown in FIG.  7 . 
     To provide an ultrafiltration function, the cycler  14  can also include a fluid removal module  118  (see FIG.  7 ). In the illustrated embodiment, the fluid removal module  118  includes a fluid removal line  120  and an in-line pump  122  upstream of the flow rate sensor  112  in the outlet line  104 . The pump  122  draws additional fluid across the membrane  26  from the dialysis solution, thereby reducing the overall fluid level of the patient. 
     In the illustrated embodiment, the fluid removal module  118  includes means  124  for monitoring the volume of excess fluid removed. The means  124  can provide a fixed volume measurement chamber, a valve and timing device, or a container with a weight sensing device. 
     A comparable ultrafiltration function can likewise be achieved in the same manner in the batch flow arrangement shown in FIG.  5 . 
     V. Reuse 
     (A) Reusing the Regeneration Solution Paths 
     As before described, the portions of the set  12 , through which peritoneal dialysis solution flows from and to the patient&#39;s peritoneal cavity  20 , can be removed from the cycler  14  and disposed of following each treatment. In this arrangement, the tubes through which the regeneration solution flows during the procedure can also be disposed of after treatment. 
     Alternatively, the fluid source  40  and associated tubes coupled to it can be cleaned and disinfected following each treatment for reuse. In one embodiment, the cleaning and disinfection can be accomplished by flowing heated water, e.g., at 80° C., for, e.g., 1 hour through the fluid source  40  and associated tubes. In another embodiment, the cleaning and disinfection can be accomplished by adding chemicals to water conducted through the fluid source  40  and associated tubes, followed by a water rinse and disinfectant and residual testing. 
     (B) Reusing the Patient Side Solution Paths 
     In an alternative embodiment, the portions of the set  12  through which peritoneal dialysis solution flows from and to the patient&#39;s peritoneal cavity  20  can themselves be cleaned and disinfected for reuse, along with or independent of the fluid source  40  and associated tubes coupled to it. 
     In one embodiment, the cleaning and disinfection can be accomplished by connecting the patient connectors  74  and  84  together and circulating hot water (e.g., 80° C.) for, e.g., 1 hour. The remaining electrolytes in the patient side  28  of the fluid pathway will cross the membrane  26  into the water on the regeneration side  30 . Circulating hot water through the fluid source  40  and associated tubes on the regeneration side  30  will bring the entire set to a cleaning and disinfecting temperature. After cooling, the regeneration solution side is flushed to remove pyrogenic material. The patient side  28  is likewise flushed with fresh, bagged sterile peritoneal dialysis solution to remove pyrogenic material and to make ready for the next treatment. 
     In one embodiment, the membrane device  22  in the patient side  28  and the filter  102  in the regeneration side  30  are each pressure tested to determine proper function following heat disinfection. 
     As an alternative embodiment, the tubing serving the patient side  28  of the membrane device  22  can be removed and disposed of following the cleaning and disinfection process, and replaced with new components. 
     In an alternative embodiment, a high level disinfectant comprising chemical additives can be circulated through the tubing serving the membrane device  22  or fluid source  40 . The disinfectant can be contained in a disinfection container source  132  coupled to the regeneration module  126  (see FIG.  7 ). The disinfectant in the source  132  is mixed or proportioned into the solution as it is conveyed from the regeneration module  126 . During this time, the patient connectors  74  and  84  can be inserted into a shunt container  126 , to dispense the disinfectant through the patient side  28  of the membrane device  22  and associated tubes. 
     The fluid source  40  and associated tubing is disinfected and then rinsed out by purified water, and tested for disinfectant residue. The patient side  28  tubes are flushed are flushed with new, bagged sterile dialysis solution to flush out pyrogenic material and tested for removal of the chemical agents, and to make the system  10  ready for the next treatment. 
     Various features of the invention are set forth in the following claims.