Drain and fill logic for automated peritoneal dialysis

Abstract

To provide an APD cycler with improved drain control.SOLUTION: The present system and method in one embodiment limit maximum instantaneous peritoneal volume to a comfortable level, while allowing a dialysis machine to advance to fill prescribed volume whenever the drain ends after a minimum drain percentage has been attained. If a low drain condition occurs, the nominal fill volume is lowered and a therapy cycle is added, so that a prescribed total amount of fresh therapy fluid is used during therapy, maximizing therapeutic benefit. Allowable residual volume at the end of an incomplete drain is increased, thereby lowering a probability of a subsequent low drain condition.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates generally to peritoneal dialysis, and specifically to a peritoneal dialysis system useful for manipulating the number of cycles, drain volume, and fill volume in a multi-cycle dialysis therapy. [Background technology]

[0002] Automated peritoneal dialysis ("APD") is a natural evolution of continuous ambulatory peritoneal dialysis ("CAPD"), which allows the patient to introduce the entire contents of a dialysis solution bag into their peritoneum and allow the volume to dwell for three to six hours. After the dwell period, the fluid is drained by gravity. The above process is typically repeated three or four times daily as needed. Working adults may perform exchanges at home before leaving for work, at the workplace during lunch hours, when the patient gets home from work, and just before the patient goes to bed. Some school-age patients follow a similar routine, except that they perform their daytime exchanges at school.

[0003] APD machines (sometimes called "circulators") perform sequential exchanges at night while the patient sleeps, making APD a more convenient treatment. Also, treatment is performed in the privacy of the patient's home so that others do not need to know that the patient is receiving dialysis treatment. Not surprisingly, most patients prefer APD to CAPD.

[0004] However, there are some important differences between CAPD and APD. CAPD is typically performed with the patient sitting upright in a chair, while APD is typically performed with the patient lying down. The patient's internal catheter travels downward into the bottom of the patient's peritoneal cavity (pelvic region) during the day when the patient is awake, and therefore may not be in the optimal position for draining when the patient is in a prone or lying position. Even if the catheter is in the correct position, the supine or sitting position is generally better for draining than the prone or lying position. Thus, APD therapy may suffer from incomplete drainage.

[0005] Continuous cyclic peritoneal dialysis ("CCPD") is one of the common APD therapies because the therapy provides complete drainage after total dwell and minimizes the possibility of overfilling due to ultrafiltration or fluid being removed from the patient's body. However, CCPD can present problems when the patient is not well drained. In nocturnal therapy, the patient is likely to be awakened or not want to get up about every 1.5 hours for a more complete drainage.

[0006] Thus, in some cases, CCPD therapy circulators proceed from drain to fill after a minimum percentage of the patient's previous fill volume has been drained, for example when the drain flow rate slows to a point where time that could be used for therapeutic effect is wasted. An alarm is typically triggered if the drain flow rate slows to a certain rate before the minimum drain rate is exceeded. The HomeChoice / Pro® APD circulator provided by the applicant of the present disclosure is considered one of the best circulators on the market, and has fewer alarms compared to its competitors. Nevertheless, low drain volume alarms occur.

[0007] Therefore, there is a need for an APD recycler having improved emissions control. Summary of the Invention [Means for solving the problem]

[0008] This disclosure describes systems and methods for performing medical fluid therapy, such as peritoneal dialysis. In a preferred embodiment, the systems and methods operate with an automated peritoneal dialysis machine, such as the HomeChoice® machine, marketed by the applicant of the present disclosure. The automated peritoneal dialysis machine includes a pump and one or more controllers, processors, computers, or memories (collectively referred to herein as logic implementers or control units) for operating the pump and other automated equipment of the machine. The machine also includes a user interface, including, for example, a video monitor and one or more input devices for inputting information into the control unit.

[0009] The disclosed systems and methods seek to maximize therapy performance, patient comfort, and patient safety. With respect to therapy performance, the disclosed systems and methods strive to utilize all of the available prescribed therapy fluid or dialysis solution. By doing so, the systems and methods maximize performance by attempting to utilize all of the osmotic gradient, which maximizes the therapy's ability to remove waste and toxins, and also remove excess water or ultrafiltrate ("UF") from the patient.

[0010] With regard to patient comfort and safety, the system and method can set a maximum allowable instantaneous peritoneal volume, above which the system and method will not allow the patient's peritoneum to fill. The maximum fluid volume that the patient's peritoneum must hold occurs at the end of the dwell phase. The dwell phase occurs after the fill phase and before the drain phase, constituting a cycle of therapy. The fill phase adds an initial volume of fluid to the patient's peritoneum. If the previous drain phase does not result in complete drainage, even before filling, the patient's peritoneum has a residual volume of fluid. Then, at the end of the fill phase, the volume of fluid in the patient's peritoneum includes the residual drain volume plus the fill volume. Over the dwell phase, the ultrafiltration volume is drawn from the patient and is added to the residual drain volume and the fill volume already present in the patient's peritoneal cavity. The system and method of the present disclosure ensure that the estimated peritoneal volume (the sum of the three volumes: residual drain, fill, and ultrafiltration) does not exceed the maximum allowable peritoneal volume at the end of the dwell.

[0011] Furthermore, with regard to patient comfort, the disclosed system and method seeks to limit low drainage alarms as much as possible. Automatic peritoneal therapy is often performed at night while the patient is asleep. The disclosed APD machine is provided with a low drainage alarm that wakes the patient at the end of the drainage phase if a minimum percentage of the estimated peritoneal volume at the end of the dwell has not been drained from the patient. Sometimes the patient may be in a physical position during sleep that is not conducive to successful drainage, for example, the patient is partially twisted or occluded. The drainage alarm alerts the patient to change body position, but in doing so, wakes the patient. Excessive drainage alarms are undesirable and reduce the overall quality of APD therapy and patient comfort.

[0012] The APD machine, in one embodiment, is configured to initially provide the patient, physician, or clinician with the option of performing a continuous cyclic peritoneal dialysis ("CCPD") therapy or a tidal therapy. Examples of suitable CCPD and tidal therapies for the APD machines and systems of the present disclosure are described herein.

[0013] In one CCPD therapy embodiment of the disclosed system and method, the minimum drainage rate is set to an initial level. Again, the minimum drainage rate is the minimum percentage of the estimated peritoneal volume at the end of the dwell that needs to be drained over the drainage phase to avoid a low drainage alarm. The initial minimum drainage rate can be set, for example, by a physician's prescription. Alternatively, the initial minimum drainage rate is set in the APD machine's memory using a formula in which the minimum drainage rate is determined by adding the fill volume per cycle to the expected UF per cycle and dividing the sum by the prescribed maximum peritoneal volume. A typical initial minimum drainage rate can be, for example, between 70 and 85 percent.

[0014] In another alternative embodiment, the low discharge alarm threshold is determined by a second formula that determines the threshold volume, called maximum residual volume, below which the estimated peritoneal volume must be reduced to avoid a low discharge alarm. The corresponding formula is obtained by subtracting the filling volume per cycle and the expected UF per cycle from the maximum peritoneal volume. The resulting maximum residual volume is then set at a level such that subsequent filling and ultrafiltrate ("UF") retention volumes do not exceed the maximum peritoneal volume.

[0015] If the initial minimum drain rate is not achieved at the end of one of the drain phases, instead of waking the patient up with an alarm, the CCPD system and method (i) adds additional fill, dwell, and drain cycles, (ii) divides the remaining total volume of unused dialysate left to be delivered to the patient by the n+1 remaining cycles instead of n cycles, thus reducing the amount of fill volume for each n+1 remaining fill phase, (iii) reduces the amount of expected UF for each dwell phase, where the expected UF can be considered as a percentage (e.g., 8%) of the reduced fill volume as opposed to the same percentage of the previous unreduced fill volume per phase, and (iv) calculates a new lower minimum drain rate by adding the new fill volume per cycle to the new expected UF per cycle and dividing the sum by the prescribed maximum peritoneal volume. Or alternatively, the new maximum residual volume is calculated by subtracting the new fill volume per cycle and the new expected UF per cycle from the prescribed maximum peritoneal volume.

[0016] If the initial discharge rate is not met and cycles are added, but the actual discharge volume or rate meets the new reduced discharge rate, treatment continues with an additional n+1 amount of cycles, a new loading volume per cycle, a new expected UF per cycle, and a new minimum discharge rate for each remaining discharge. If the total prescribed treatment time is important and is set as a parameter not to be exceeded, the dwell periods for each of the remaining n+1 dwell steps are shortened so that the original prescribed total treatment time is not exceeded despite the added cycles. If the total prescribed treatment time is less important and is not set as a parameter to remain constant, the dwell periods can remain unchanged or be shortened by a smaller amount so that the total treatment time is extended.

[0017] If the minimum discharge rate is not met and the actual discharge rate with the cycle added still does not meet the newly determined, reduced discharge rate, the system and method adds a second additional cycle to further reduce the fill capacity per cycle, the expected UF per cycle, and therefore the minimum discharge rate per the formula discussed above. This sequence continues until the actual discharge rate meets at least the minimum discharge rate.

[0018] In an alternative CCPD therapy embodiment, the disclosed system and method sets the new fill volume to a new nominal or average value instead of dividing the total remaining volume of unused dialysate left to be delivered to the patient by the n+1 remaining cycles. For example, if the total volume of unused dialysate delivered to the patient throughout the entire treatment is 12,000 milliliters and the initial number of cycles is 4, the initial nominal fill volume per cycle is 3,000 milliliters. When an additional 5th cycle is added due to insufficient drainage, the nominal fill volume per cycle becomes 2,400 milliliters. The new nominal fill volume per cycle is then set as the fill volume, even if one or more previous fills used 3,000 milliliters. As a result, the fill of the last cycle is shortened to whatever amount of unused solution is allowed. Thus, it should be understood that again, all unused solution is used to maximize the therapeutic effect.

[0019] The system and method in an embodiment establishes a separate very low discharge threshold that will trigger an alarm to awaken the patient when some form of severe flow obstruction is clearly occurring (i.e., when the actual discharge is so low that the low discharge is clearly not due to the patient being unable to discharge, in one implementation the system and method will awaken the patient in such cases. However, it should be understood that the system and method at least attempts to substantially limit low discharge alarms and associated patient awakenings.

[0020] The above procedure can be performed at multiple different times during the treatment course, tapering the minimum drain rate when necessary. The system and method keeps the minimum drain rate as an asymptote that does not exceed the maximum allowable peritoneal volume by making it a small fraction of that volume. Also, because the calculation of the minimum drain rate takes into account the remaining fill volume, e.g., nominal fill volume, remaining to be delivered to the patient, the system and method ensures that the patient uses all of the prescribed treatment volume of unused dialysate during the treatment course, which in turn maximizes the effectiveness of the treatment.

[0021] The CCPD system and method discussed above, in one embodiment, is automatically initiated when the APD machine detects a low discharge volume / rate. In an alternative embodiment, the CCPD system and method are offered to the patient as an option. In this alternative embodiment, CCPD therapy can be performed according to prescription until a low discharge volume / rate problem occurs, at which point the APD machine wakes the patient up. The patient is requested to attempt to correct the incomplete discharge. The patient is then provided with the option to continue treatment according to the original prescription or to change to a minimum discharge volume / rate correction mode. If a patient believes that the treatment can continue as originally prescribed without further discharge problems, but would like to be given the opportunity to complete discharge if another low discharge situation occurs and / or for any other reason, the patient can continue CCPD therapy as originally prescribed. Alternatively, if the patient believes that the minimum discharge volume / rate is currently set too high, based on how the patient is draining and / or for any other reason, the patient can enter a minimum discharge volume / rate correction mode that operates according to one of the embodiments described herein in an attempt to prevent further low discharge alarms while maintaining patient safety, comfort, and treatment effectiveness.

[0022] In one preferred tidal therapy embodiment, the disclosed system and method begins with a CCPD therapy, which may be a CCPD therapy already stored in the memory of the APD machine. The tidal therapy system and method automatically modifies the selected CCPD therapy to a tidal therapy based on the patient's, nurse's, or clinician's selection to add only one additional cycle, or alternatively to add two additional cycles (or more, if desired). If only one additional cycle is added, the selected CCPD therapy is modified to leave a first residual volume (e.g., 25% of the initial fill) in the patient's peritoneal cavity at the end of each normal cycle, excluding the last cycle where the patient can perform a complete drain. If two additional cycles are selected to be added, the residual drain volume is set to a higher level, e.g., 40% of the initial fill. In either case, the prescribed residual drain volume helps the patient avoid low drain alarms.

[0023] As discussed in detail below, once the desired residual volume and number of cycles to be added are known, the tidal therapy is automatically derived from the selected CCPD therapy to (i) deliver the same total amount of fresh dialysis solution to the patient over all of the cycles as would be delivered in the selected CCPD therapy, (ii) ensure that the patient is filled after each fill phase to the same level as would be filled in each phase of the selected CCPD therapy (considering either fresh dialysate for the first fill phase only, or a combination of fresh dialysate and residual drain volume for fill phases occurring after the first fill phase), and (iii) ensure that the tidal therapy has the same total treatment duration as the selected CCPD therapy. In making the automatic conversion from CCPD to tidal therapy, if additional cycles are added, the dwell duration is reduced to a first amount for a "plus 1" tidal therapy, further reduced to a second amount for a "plus 2" therapy, and so on.

[0024] Thus, the aforementioned tidal therapy is easily programmed. The patient uses the "plus 1" or "plus 2" version based on whether the patient, doctor, or clinician believes that the lower residual drainage capacity of the "plus 1" cycle tidal therapy will avoid a low drainage state, or whether the patient, doctor, or clinician believes that the higher residual drainage capacity of the "plus 2" cycle tidal therapy is required. Once selected, the APD machine automatically programs itself to perform the tidal therapy based on the selected basal CCPD therapy.

[0025] It is therefore an advantage of the present disclosure to provide a peritoneal dialysis system and method that seeks to ensure that the entire prescribed volume of fresh dialysate is delivered to the patient during the course of treatment.

[0026] Another advantage of the present disclosure is to provide a peritoneal dialysis system and method that ensures that therapeutic benefits are maximized.

[0027] A further advantage of the present disclosure is to provide a peritoneal dialysis system and method that ensures that the maximum allowable peritoneal volume is not exceeded.

[0028] Moreover, a further advantage of the present disclosure is to provide a peritoneal dialysis system and method that limits patient awakening due to low drainage alarms during treatment.

[0029] Yet another advantage of the present disclosure is to provide a peritoneal dialysis system and method that maintains the full duration of a prescription for treatment.

[0030] A still further advantage of the present disclosure is to provide a peritoneal dialysis system and method in which the patient is provided with the option to continue the prescribed therapy or to allow the APD machine to modify the prescribed therapy in an attempt to avoid further low drainage alarms.

[0031] Still further, an advantage of the present disclosure is that it provides a patient, nurse, or physician with the option of performing either continuous cyclic peritoneal dialysis therapy or tidal therapy.

[0032] Yet another advantage of the present disclosure is that it provides a nurse or physician with a method to automatically convert continuous cyclic peritoneal dialysis ("CCPD") therapy to tidal peritoneal dialysis therapy that maintains equivalent treatment volume and duration.

[0033] Additional features and advantages are described herein, and will be apparent from the following detailed description and drawings. [Brief description of the drawings]

[0034] [Figure 1] FIG. 1 is a perspective view of one embodiment of a dialysis system having self-regulating drainage logic in accordance with the present disclosure. [Diagram 2] FIG. 2 is a perspective view of one embodiment of a disposable cassette operable with a dialysis system having self-regulating drainage logic in accordance with the present disclosure. [Diagram 3] FIG. 3 is a logic flow diagram illustrating one continuous cyclic peritoneal dialysis ("CCPD") treatment method or algorithm of the present disclosure. [Figure 4] FIG. 4 is a logic flow diagram illustrating another CCPD method or algorithm of the present disclosure. [Diagram 5] FIG. 5 is a treatment graph illustrating another method or algorithm of the present disclosure. [Figure 6] FIG. 6 is a treatment graph illustrating another method or algorithm of the present disclosure. [Figure 7] FIG. 7 is a treatment graph illustrating another method or algorithm of the present disclosure. [Figure 8] FIG. 8 illustrates one embodiment of the tidal therapy method or algorithm of the present disclosure. [Figure 9] FIG. 9 illustrates one embodiment of the tidal therapy method or algorithm of the present disclosure. [Figure 10] FIG. 10 illustrates one embodiment of the tidal therapy method or algorithm of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] (Dialysis system in general) Referring now to the drawings, and in particular to FIGS. 1-2, a renal failure treatment system 10 is provided. The system 10 is generally applicable to any type of automated peritoneal dialysis ("APD") system. The system 10 in the illustrated embodiment includes a dialysis instrument 12. The dialysis instrument 12 is configured for the provided APD treatment system. The dialysis instrument 12 includes a central processing unit ("CPU") and memory, and may include one or more additional processors and memories operable with the CPU (e.g., safety devices, valves, heaters, pumps, video, and audio (e.g., voice guidance) controllers), which may collectively be referred to as a logic implementer or control unit. The logic implementer operates with a user interface ("UI"), such as a graphical user machine interface ("GUI"), for example, via a video controller component of the logic implementer. The GUI includes a video monitor 20 and one or more types of input devices 22, such as a touch screen or an electromechanical input device (e.g., a membrane switch). The CPU is also configured to receive instructions and / or data from the GUI, a remote memory storage device, an internet or database connection, and / or a wireless connection device.

[0036] The logic implementer in cooperation with the video monitor 20 visually provides treatment instructions and setup confirmations to the patient or caregiver via text / graphics. For example, text / graphics may be displayed to (i) provide instructions regarding placement of the distal end of the patient line onto the instrument 12 (discussed below) for priming, and / or (ii) inform the patient when the patient line is fully primed. Additionally or alternatively, a voice guidance controller of the logic implementer in cooperation with the speaker 24 provides (i) and / or (ii) as described above.

[0037] As seen in Figure 1, the dialysis instrument 12 receives and operates with a disposable set 30. The disposable set 30 includes one or more supply bags 32a through 32c (collectively referred to herein as supply bags 32, or generally and individually as supply bags 32), shown herein as dual chamber supply bags that separate two fluids via a peelable or frangible seal 34. The disposable set 30 also includes a drain bag (not shown), a warming bag 36, tubing 38a through 38d (collectively referred to herein as tubing or tubes 38, or generally and individually as tubes 38), and a disposable pump / valve cassette 50 (Figure 2).

[0038] The warming bag 36 is used in a batch heating operation where the top of the appliance 12 batch heats the fluid in the bag 36. The system 10 can also pump the used fluid to a house drain, such as a bathtub, toilet, or sink, instead of a drain bag, in which case a drain bag is not required.

[0039] Although three supply bags 32 are shown, system 10 may employ any suitable number of supply bags. Supply bag 32 is shown having multiple chambers 42a and 42b separated by frangible seals 34 that hold different solutions depending on the type of therapy being employed. For example, chambers 42a and 42b may hold a buffer and glucose for an overall PD dialysate having a desired glucose concentration. Supply bag 32 may alternatively be a single chamber bag that holds a single premixed solution, such as a premixed PD dialysate having a desired glucose concentration.

[0040] As seen in Figures 1 and 2, the disposable cassette 50 connects to the supply bag 32, drain bag, and warming bag 36 via tubes 38a, 38b, and 38c, respectively. Tube 38d extends from the cassette 50 to the patient connection 44. The cassette 50, in one embodiment, includes a rigid structure having a rigid outer wall 52 and a pump chamber (60a and 60b as shown in Figure 2), a valve chamber (e.g., a volcano valve chamber), and an intermediate base wall (not shown) from which rigid fluid pathways extend. A rigid fluid port 56 extends from the side wall 52, is in fluid communication with the rigid cassette pathways, and sealingly connects to the tubing 38. The tubing 38 can be secured to the port 56, in which case the bag 32 is spiked to allow fluid from the bag to flow through the tubing 38 and into the cassette 50. Alternatively, the tubing 38 is fixed to the bag 32 in which case the port 56 or mating tubing end is spiked to allow fluid from the bag 32 and tubing 38 to flow into the cassette 50.

[0041] A pair of flexible membranes or sheets 58 (only one shown) are sealed to the outer rigid wall 52 of the cassette. The cassette 50 is sealed within the instrument 12 such that the sheets 58 form the exterior of the rigid fluid pathways of the rigid cassette body. One of the sheets is moved to pump fluid through the pump chambers (60a and 60b) and to open and close the cassette valves.

[0042] The instrument 12 can actuate the pump and valve chambers of the cassette 50 pneumatically, mechanically, or both. The illustrated embodiment uses pneumatic actuation. The HomeChoice® APD system, marketed by the applicant of the present disclosure, uses a pneumatic system, for example, as described in U.S. Pat. No. 5,350,357 ("the '357 patent"), the entire contents of which are incorporated herein by reference. As seen in FIG. 2, the instrument 12 includes a flexible membrane 14 that creates distinct sealing regions with a cassette sheet 58 in each of the pump and valve chambers of the cassette 50. The membrane 14 moves with the sheet 58 in these regions to open and close the valve chambers and to pump fluid through (in and out of) the pump chambers. A cassette interface plate (not shown) is located behind the membrane 14 and includes first and second chamber halves (not shown) that mate with the chamber halves 60a and 60b of the cassette 50 to form a pair of fixed volume pump chambers.

[0043] The instrument 12 in the illustrated embodiment includes a door 16 that closes against a cassette 50. The door 16 includes a press plate 18 that can be operated mechanically (e.g., via closing the door) and / or pneumatically (e.g., via an inflatable bladder located in the door behind the press plate). Pressing the plate 18 against the cassette 50 in turn presses the cassette 50 against a pump membrane 14 that cooperates with a seat 58 of the cassette 50 to pump fluid through chambers 60a and 60b and to open and close the cassette valve chambers.

[0044] The cassette interface plate located behind the membrane 14 is configured to apply positive or negative pressure to the cooperating membrane 14 and cassette sheet 58 at different valve and pump regions. For example, positive pressure is applied to the membrane 14 / sheet 58 at regions of the membrane / sheet located within the rigid inner walls of the cassette 50 that define pump chambers 60a and 60b, and within half of the chambers of the interface plate (not shown), to push fluid out of the pump chambers. Negative pressure is applied to the membrane 14 / sheet 58 at these same regions to draw fluid into the pump chambers. Similarly, positive pressure is applied to the membrane 14 / sheet 58 at regions of the sheet in the interface plate that define the rigid inner walls of the cassette 50 and the valve chambers to close the outlet ports of the valve chambers. Negative pressure is applied to the membrane 14 / sheet 58 at those same regions to open the outlets of the valve chambers.

[0045] U.S. Patent No. 6,814,547 ("the '547 patent"), assigned to the assignee of the present disclosure, discloses a pump mechanism that uses a combination of pneumatic and mechanical actuation, with reference to Figures 17A and 17B and related document description, which are incorporated and relied upon herein by reference. Figures 15, 16A and 16B of the '547 patent and related description, which are incorporated and relied upon herein by reference, teach the use of mechanically actuated valves. Either or both of these mechanisms can be used in place of the purely pneumatic system of the HomeChoice® machine.

[0046] The '357 and '547 patents also teach different systems and methods for knowing and controlling the amount of unused dialysate delivered to the patient, the amount of effluent dialysate removed from the patient, and therefore the amount of additional fluid or ultrafiltrate ("UF") removed from the patient, which are incorporated and relied upon herein by reference. UF is blood and tissue fluid that the patient accumulates between treatments due to the patient's failing kidneys. Dialysis treatments remove this blood and tissue fluid as UF in an attempt to return the patient to "dry weight." Either of the UF control systems and methods of the '357 and '547 patents can be used as described below to control the fill and drain volumes according to the method of system 10.

[0047] Additional machines that are particularly suitable for employing the self-regulating drainage logic systems and methods of the present disclosure are disclosed in published International Applications Nos. WO2009094179, WO2009094183, WO2009094185, WO2009094182, WO2009094184, and WO2009094186, the entire contents of each of which are incorporated by reference into and relied upon herein.

[0048] (Drain and fill logic for automated peritoneal dialysis) It is contemplated that when a patient initiates treatment on the machine 12 of the system 10, the system 12 will provide the patient with a variety of treatment options. These treatment options can be selected on a treatment-by-treatment basis (e.g., daily) using the video screen 20 and / or speaker 24 and input device 22 so that the treatment options can be administered alternatively or otherwise mixed. The system 10 can be configured for the physician or patient to select the treatment profile to be administered. If selected by the physician (nurse or clinician), the treatment profile can be downloaded to the machine 12 via an internet or data network linked to the APD machine 12, or stored on a memory device, such as a flash drive or universal serial bus ("USB") drive, and plugged into a port on the machine 12 that is in communication with the logic implementer of the APD machine 12.

[0049] It is contemplated that system 10 provides patients, clinicians, and physicians with at least one continuous cyclic peritoneal dialysis ("CCPD") therapy option and at least one tidal therapy option. Generally, CCPD therapy attempts to completely drain the patient after each cycle, while tidal therapy leaves a preset amount of dialysate in the patient at the end of each drain, except for the final drain (residual drain volume), and then fills the patient with a smaller preset amount of unused solution at the next fill, except for the first fill, which typically occurs after a full drain or when the patient is otherwise at or near full empty.

[0050] Figures 3 through 7 illustrate various embodiments of CCPD therapy for system 10 that can be modified to pseudo-tidal therapy if the patient is experiencing incomplete drainage. Figures 8 through 10 illustrate embodiments of tidal therapy for system 10.

[0051] (1.CCPD therapy) 3, method 100 illustrates one possible CCPD method or algorithm for implementation in the control unit or logic implementer of APD machine 12. As a CCPD therapy, method 100 attempts to fully drain the patient after each cycle. As will be seen below, if the patient experiences a low drainage condition, (i) the patient can be provided with the option to increase the patient's allowed residual drainage capacity in an attempt to reduce the required minimum drainage volume or rate and thus allow treatment to continue without further alarms even if the patient experiences further drainage problems, or (ii) the machine can do so automatically.

[0052] Method 100 begins with oval 102. In block 104, method 100 allows a doctor, nurse, clinician, or patient to input or recall an initial prescribed fill volume, which is multiplied by the initial prescribed number of cycles, each cycle having a fill phase, a dwell phase, and a drain phase, resulting in a prescribed total of dialysate volume delivered to the patient. The prescribed total of dialysate volume in the fill phase delivered to the patient in an embodiment is the entire volume delivered to the patient during a normal treatment cycle, not including the final fill volume delivered to the patient after the cycle is completed. The final fill volume is present in the patient after the patient is disconnected from APD machine 12 and is removed before the next set of normal treatment cycles begins, during a daytime exchange, or overnight.

[0053] In one embodiment, the patient inputs (at block 104) an initial fill volume, which is assumed to be the volume for each fill phase of the prescription cycle, before each treatment. The patient also inputs a final fill volume before each treatment.

[0054] In addition to the initial prescribed fill volume and / or the prescribed total dialysate volume for the fill phase, the method 100 allows the doctor, nurse, clinician, or patient to input or recall the expected UF volume per cycle, the maximum allowable peritoneal volume, the initial minimum drain volume, optionally a threshold minimum drain volume, the initial treatment cycle number, and optionally the total treatment time, as seen in block 104. The expected UF volume per cycle can be the fill volume per cycle multiplied by a percentage, for example, the fill volume multiplied by 8 percent. This percentage can be optimized for the patient, taking into account the patient's transport characteristics. It is therefore contemplated that the doctor, nurse, clinician, or patient inputs an optimized UF rate for the patient, for example, once for multiple treatments, so that the expected UF volume can be recalculated whenever the fill volume changes. Thus, block 104 indicates that the expected UF volume may under normal circumstances be recalled from the memory of the APD machine 12 (and not re-entered by the patient for each treatment) and updated, for example, by a doctor, nurse, clinician, or the patient periodically after the patient's transport capacity has been re-evaluated.

[0055] The maximum allowable instantaneous peritoneal volume is the maximum amount of fluid that can be present in the patient's peritoneum at any one time. This generally occurs at the end of the dwell phase of the cycle, just before ensuring that the drain phase is initiated. The maximum allowable peritoneal volume can be the sum of three different fluid volumes. First, it includes the fill volume that is input during the fill phase of the cycle. Second, it includes the UF volume that is drawn into the patient's peritoneum during the course of the dwell phase by the osmotic gradient provided by the dialysate. Third, the maximum allowable peritoneal volume can also include the residual drain volume due to incomplete drainage during the previous drain phase. Incomplete drainage occurs naturally as the patient pools fluid so that draining to empty does not drain all of the previous fill volume. Regardless of how much the three components contribute to the combined instantaneous peritoneal volume, the method 100 does not allow the instantaneous peritoneal volume to exceed the maximum allowable peritoneal volume. It should then be understood that better patient drainage allows more unused solution and more UF to be produced accordingly.

[0056] The maximum allowable peritoneal volume can be optimized for the patient, as can the expected UF volume / UF rate, where the optimization is generally based on the patient's size and comfort level with respect to tolerating fluids that reside in and create pressure within the patient's peritoneum. Again, it is contemplated that a doctor, nurse, clinician, or patient may enter the maximum allowable peritoneal volume once for multiple treatments. Thus, block 104 indicates that the maximum allowable peritoneal volume may be recalled from the memory of the APD machine 12 under normal circumstances (and not re-entered by the patient for each treatment) and updated, for example, by a doctor, nurse, clinician, or patient periodically after the patient has been re-evaluated.

[0057] The initial minimum drain volume or drain rate, in one embodiment, is the minimum amount of the filling volume and expected UF that needs to be drained to allow the treatment to proceed as prescribed. The initial minimum drain volume or drain rate, in one embodiment, is set high enough to allow the treatment to proceed through the prescribed number of cycles without the patient's instantaneous peritoneal volume exceeding the maximum allowable peritoneal volume, despite the fact that each drain may leave a residual volume in the patient before each subsequent filling step. For example, the initial minimum drain rate can be set to be 85% of the prescribed filling volume plus the expected UF. Since the initial minimum drain rate takes into account 85% of the prescribed filling volume plus the expected UF, the residual drain volume adds a step component to each cycle (see Figures 4 to 6) so that the instantaneous peritoneal volume at the end of each dwell increases during each cycle. However, the initial minimum drain rate is set high enough that even at the end of the dwell period of the last cycle, assuming the patient just meets the minimum drain requirements in each cycle, the instantaneous peritoneal volume does not exceed the maximum allowable peritoneal volume and therefore does not overtax the patient's comfort level.

[0058] The patient typically wakes up for the drainage phase of the final cycle, which may be set to occur in the morning when the patient is waking up from sleep. Thus, the patient can move around and drain all or virtually all of the peritoneal volume, including volume that has accumulated during the course of the treatment. The system 10 and method 100 take into account that the patient may change position while sleeping such that the patient's indwelling catheter is not in an optimal position for retention. The initial minimum drainage volume or drainage rate is generally determined empirically, with 85% being considered a good starting point. Again, it is contemplated that the doctor, nurse, clinician, or patient inputs the initial minimum drainage volume or drainage rate once for multiple treatments. Thus, block 104 indicates that the maximum allowable peritoneal volume can be recalled from the memory of the APD machine 12 under normal circumstances (not re-entered by the patient for each treatment) and updated periodically, for example, by the doctor, nurse, clinician, or patient after the patient has gained treatment experience with the APD machine 12.

[0059] In an alternative embodiment, as shown in Figures 4 to 6, an initial minimum drainage capacity / rate is calculated using a formula that is used throughout treatment whenever the minimum drainage capacity rate needs to be adjusted.

[0060] Block 104 also indicates that, in one embodiment, a threshold minimum drain volume or rate may be optionally set. The system 10 and method 100 also recognize that the patient may change position while sleeping, causing the patient fill / drain line 38d (from the cassette 50 to the patient) to become partially or completely blocked. Or, the drain tube 38b (from the cassette 50 to the drain) may become partially or completely blocked. Both situations may significantly limit the effectiveness of the drain phase, and the machine 12 should wake the patient in such a situation to clear the blockage. The threshold minimum drain volume may be set to be equal to or less than 50% of the combined fill and expected UF volumes.

[0061] It is contemplated that a threshold minimum discharge volume or rate may be set at the factory and rarely or never updated at block 104. In alternative embodiments, a line blockage may be determined more instantaneously, for example, by sensing a pressure spike, such that setting a threshold minimum discharge volume or rate is done as an additional line blockage (or other serious error condition) check or eliminated entirely.

[0062] The system 10 and method 100 are not limited to any particular type of treatment setting. The total combined fill volume, or the total volume of fresh dialysate delivered to the patient over each of the cycles, is generally set by prescription, e.g., 12 or 18 liters. The duration needed to fill and drain the patient, i.e., the duration of the fill and drain phases, is a function of the pumping capacity of the machine 12 and the amount needed to fill and drain, respectively, which are generally known and set. Three interrelated variables remain: the total number of cycles, the duration of the dwell phase per cycle, and the total treatment time or duration. The total treatment time or duration may or may not include the time needed to first drain the patient of the last fill of the previous treatment, or the time needed to perform the last fill after a cycle is completed. Nevertheless, the setting of any two of (i) the total number of cycles, (ii) the duration of the dwell phase per cycle, and (iii) the total treatment time or duration generally sets the third variable. In the illustrated embodiment, a nurse, doctor, clinician, or patient sets the total treatment time and the initial number of cycles at block 104. The total treatment time and the initial number of cycles are then known and the dwell duration per cycle is calculated. The system 10 and method 100 can alternatively operate to set (i) the dwell duration and number of cycles, meaning that the total treatment time is the dependent variable, or (ii) the dwell duration and total treatment time such that the initial number of cycles is the dependent variable.

[0063] The patient typically inputs one of the two-thirds combinations discussed above for the number of cycles, duration of the dwell phase, and total treatment time, which allows for the day's treatment to be tapered if necessary, at block 104. However, system 10 and method 100 are applicable even if the two-thirds combination is pre-set on a memory device that is read by APD machine 12, for example, via a prescription loaded from a clinician or physician from a remote computer.

[0064] As seen in block 106, the method 100 performs any necessary pre-cycle drains so that therapy begins when the patient is empty or close to empty. The initial drain is typically from the last spent fill after the previous day's exchange, or a spent intraday exchange. The initial drain is typically performed while the patient is still awake so that the patient can move around and drain as completely as possible.

[0065] At block 108, the method 100 performs a treatment cycle, including a fill phase, a dwell phase, and a drain phase. In the illustrated embodiment, the initial cycle number and total treatment time are set at block 104 such that each dwell phase has a duration equal to the total treatment time minus the fill and drain times divided by the cycle number.

[0066] At diamond 110, method 100 determines whether there is another cycle. In one embodiment, normal therapy is terminated regardless of the outcome of the final drain phase. The therapy is completed or corrected via method 100 to the final cycle satisfactorily. Also, the patient receives all of the prescription fresh dialysate by the time of the final drain. Still further, the patient can be awakened at the end for the final drain and can operate to clear himself of the residual outflow volume. If the last fill (carried by the patient during the day) occurs before the patient is awakened, system 10 and method 100 consider adding the last fill volume, taking into account the expected UF from the last fill, so as not to allow the patient to be overfilled. If there is another cycle, as determined at diamond 112, method 100 moves to the minimum drain comparison at diamond 112.

[0067] At diamond 112, method 100 determines whether the previous discharge met the current minimum discharge volume or rate. For the first cycle, method 100 compares the initial minimum discharge volume (e.g., 85% multiplied by the sum of the fill volume and the expected UF) to the actual volume discharged at the end of the first cycle. If the actual volume discharged does not meet the initial minimum discharge volume, method 100 determines at diamond 114 whether the actual volume discharged at least meets a threshold minimum discharge volume, set at, for example, less than 50% multiplied by the sum of the fill volume and the expected UF. As discussed above, a line blockage may be determined using a threshold minimum discharge volume and / or different methods, for example, detecting a pressure spike. Thus, the determination of the threshold minimum discharge volume at diamond 114 may be eliminated if desired or retained as an additional check.

[0068] If at least the threshold minimum drain volume is met, then method 100 adds a cycle to the initial number of cycles entered in block 104 at block 116. Method 100 also determines a new fill volume per cycle by dividing the total remaining volume of unused dialysate to deliver to the patient during the previous n remaining cycles by the (n+1) cycle. For example, if after the first cycle the minimum drain is not met at diamond 112 and four fill stages are initially left at 2,500 milliliters per fill (leading to a total prescribed fill volume of 5 x 2,500 = 12,500 ml), then the additional cycle brings the new total number of remaining fill stages to 5 (total cycles are 6) and reduces the volume per fill stage to 10,000 / 5 or 2,000 milliliters per fill. Additionally, because the fill volume per cycle is reduced, the expected UF per cycle, which is a function of the fill volume, is also reduced at block 116 of method 100. For example, if the expected UF is 8 percent of the fill volume, the expected UF would drop from 200 milliliters to 160 milliliters in the above example.

[0069] The method 100 also calculates a new minimum discharge volume or rate at step 116 according to the following formula:

number

[0070] Method 100 then returns to the minimum discharge rate comparison at diamond 112, where it uses the new minimum discharge rate and new minimum discharge volume retroactively applied to the previous actual discharge volume to see if the previous actual discharge volume meets the updated minimum discharge rate or minimum discharge volume. If not, for example if the first previous actual discharge volume was only 1,500 milliliters and did not meet 1,555 milliliters but still exceeded the threshold minimum discharge volume (hypothetically set at 50%, resulting in (2,500+(2500×0.08))×0.5=1,350 milliliters in the example), method 100 returns to block 116 and performs that function again, adding a second additional cycle, further reducing the fill volume per cycle and the expected UF per cycle, leading to an even lower new minimum discharge rate / volume. The loop between diamond 112, diamond 114, and block 116 continues until the actual discharge volume meets the adjusted minimum discharge rate / volume.

[0071] As further illustrated in block 116, if the total treatment time is set to remain constant as a parameter, for example if the patient wishes to be woken by the machine at 7:00 a.m. regardless of what happened overnight with respect to the treatment, the duration of the dwell phase is reduced each time a cycle is added. The formula for reducing the duration of the dwell phase is somewhat complicated because adding a cycle causes the additional fill and dwell phase durations for the additional cycle to cut into the available time for the dwell. For example, if the initial prescribed treatment has a total available dwell of 390 minutes, each of the five prescribed dwells will last 78 minutes, assuming the APD machine 12 is set to have each dwell phase have the same duration. When a cycle is added in block 116, the new dwell period is not simply 390 minutes or 65 minutes, now divided by 6 minutes, but instead the additional fill and drain phase durations are first subtracted from 390 minutes, then subtracted from the 78 minutes spent over the first dwell and divided by the new remaining number of dwells. For example, if the additional fill and drain phases each take 11 minutes, then the total remaining dwell time (390-78=312 minutes) is reduced by 22 minutes to 290 minutes, which is then divided by 5 for the remaining dwell phases, resulting in 58 minutes for each remaining dwell. The above recalculation of dwell durations keeps the total treatment time constant. Again, system 10 and method 100 do not require that the total treatment time be kept constant. Instead, an additional 100 minutes ((11 for fill)+(78 for dwell)+(11 for fill)), or some lesser amount, could be added to the total treatment time if desired.

[0072] In the above example, assuming the previous actual drain volume was 2,000 milliliters, upon return to the minimum drain rate / volume comparison at diamond 112 from block 116, a new minimum drain rate / volume of 1,555 milliliters would be met. In this case, and in cases where the threshold minimum drain volume is not met at diamond 114 and the machine 12 generates an alarm to awaken the patient and clear a line blockage or other treatment impediment, as illustrated at block 118, the method 100 continues with the next treatment cycle at block 108. Up until the final cycle, any prior drain phases that do not meet the minimum drain volume / rate are corrected in the manner described above, which can occur after multiple drain phases if necessary.

[0073] When no additional cycles remain at diamond 110 , the method 100 of system 10 ends as illustrated by oval 120 .

[0074] 4, method 150 illustrates an alternative CCPD embodiment that again first attempts to fully drain the patient at the end of each cycle. The basic difference is that in the previous method 100, if the minimum drainage volume / rate at diamond 112 is not met, machine 12 automatically takes corrective action at block 116 (assuming the threshold minimum drainage volume / rate is met at diamond 114). On the other hand, in method 150, if the minimum drainage volume / rate is not met at diamond 112, the patient is instead provided with the option to take the corrective action provided at block 116.

[0075] Method 150 begins with each of the steps and alternative implementations for oval 102, block 104, block 106, and block 108 described above with respect to method 100 of FIG. 3. Block 108 is illustrated in FIG. 4 as being divided into blocks 108a and 108b, indicating that the functionality of block 108a is repeated again at block 108b, including all alternatives discussed above for block 108 of method 100 of FIG. 3. In method 150, a determination of the last cycle at diamond 110 is not provided immediately after block 108a. Instead, at diamond 112a, method 150 determines whether the patient's actual drainage has met the initial minimum drainage volume / rate in the first case (including all alternatives discussed above for diamond 112 of method 100). If so, then method 150 determines whether the last scheduled treatment cycle has occurred in the first case at diamond 110a. If so, the method 150 ends as seen in oval 120. If there is another cycle at diamond 110a, the method 150 returns the system 10 to block 108a for another fill, dwell, and drain cycle.

[0076] If the minimum drainage rate is not met at diamond 112a, then at block 124 the patient is awakened and instructed to sit upright and / or move the patient's abdomen in an attempt to complete the incomplete drainage, for example, by moving an indwelling catheter and / or releasing one or more accumulated volumes of fluid present within the patient's peritoneal cavity. Thus, method 150 provides the patient with the option to attempt to correct a failure in the minimum drainage volume / rate, as opposed to automatically adjusting the fill volume, expected UF, and minimum drainage volume / rate accordingly, as is done in method 100 of FIG.

[0077] At diamond 110b, method 150 determines, in the second case, whether the previous cycle was the last cycle. If so, method 150 again ends as seen at oval 120. If there is another cycle at diamond 110b, method 150 determines, at diamond 126, whether the patient desires system 10 to be in a mode in which the minimum discharge volume / rate is adjusted in the manner discussed above. APD machine 12 may make such a recommendation to the patient via video monitor 20, speaker 24, and / or otherwise via its user interface. The patient makes the selection to be in or out of the minimum discharge volume / rate adjustment mode via one or more input devices 22 (e.g., touch screen) in communication with the user interface and CPU of APD machine 12.

[0078] If the patient does not wish to enter the minimum drain volume / rate adjustment mode as determined at diamond 126, method 150 returns to block 108a for another fill, dwell, and drain cycle. Method 150 allows the patient to be awakened at block 124 each time a low drain condition occurs at diamond 112a, if so desired by the patient. If the patient experiences low drainage very infrequently, the patient may choose to be allowed to attempt to complete the drain for each cycle before proceeding to the next cycle, provided that the cause of the low drainage is typically due to a condition that the patient can correct.

[0079] On the other hand, if the patient feels that diamond 126 has not effectively eliminated the low drainage problem experienced in block 124, if there are continuing drainage problems, if in any case they wish to be allowed to sleep as long as possible, or for any other reason or combination of reasons, the patient may elect to enter into the minimum drainage adjustment mode at diamond 126. The patient may elect to enter into such mode after any drainage prior to the last cycle in the illustrated embodiment. Once in the minimum drainage adjustment mode, method 150 performs the remainder of the peritoneal dialysis therapy according to blocks 108b, diamond 110c, diamond 112b, diamond 114, diamond 116, and block 118 in the same manner as described above in blocks 108, diamond 110, diamond 112, diamond 114, block 116, and block 118 for method 100 of FIG. 3 (including all disclosed alternatives).

[0080] In a further alternative embodiment, illustrated in Figures 5 through 7, when the actual drainage does not meet the minimum drainage rate / volume, the fill volume per cycle is not reduced to a value based on how much total unused fluid remains to be delivered to the patient, as in methods 100 and 150, but instead is reduced to a value based on a new average amount over a new number of cycles. Figure 5 illustrates an initially prescribed treatment where the initial fill phase volume per cycle is 3000 milliliters, there are 4 cycles resulting in a total of 12,000 milliliters unused, the maximum allowable instantaneous peritoneal volume is 4000 milliliters, the expected UF is 8% or 240 milliliters per cycle, and the initial minimum drainage volume rate is now calculated using the following formula:

number

[0081] Alternatively, a minimum emission threshold is calculated and used in place of the minimum emission rate.

number

[0082] The minimum drain rate is different from the minimum drain threshold. The minimum drain rate is multiplied by the estimated patient volume at the end of the dwell to yield a volume, which is the minimum drain volume, equal to the minimum amount of fluid that needs to be drained before the next fill can occur. For the minimum drain threshold, the estimated patient volume at the end of the dwell is reduced to a volume less than the minimum drain threshold. Thus, for example, if the estimated patient volume at the end of a particular dwell is equal to 3,999 milliliters and the minimum drain threshold is 760 milliliters, the circulator should drain more than 3999-760=3,239 milliliters. Then, at the end of the drain, the expected patient volume should be only 760 mL, which is the situation at the end of cycle 3 in FIG. 5. The two formulas yield essentially the same result at the end of cycle 3 dwell, estimated patient volume=3,999 milliliters. First formula minimum drain volume=3,999 milliliters * 81% = 3,239 milliliters, allowing 760 milliliters of outflow to remain in the patient.

[0083] The difference between the two formulas is that for the first minimum discharge rate formula, the allowable residual volume is less in the first cycle and grows asymptotically. The second minimum discharge threshold formula results in a residual volume that is the same for the entire cycle. In other words, the residual volume of the minimum discharge threshold formula is the asymptote that the first minimum discharge rate formula approaches. Thus, by the time of the last cycle, the two formulas provide essentially the same results. In the first cycle, the first minimum discharge rate formula requires more volume to be discharged. However, in either formula, the maximum patient volume is not allowed to be exceeded.

[0084] 5 shows the worst case peritoneal volume scenario for 81% minimum drainage volume therapy, i.e., each actual drainage exactly meets the 81% minimum drainage volume. As shown, the maximum instantaneous peritoneal volume nevertheless exceeds the programmed limit of 4000 ml.

[0085] If the residual volume at the end of all but the last drain is insufficient, i.e. does not meet the 81% minimum drain, the therapy is modified to use the same total fluid volume of 12,000 milliliters for 5 cycles instead of 4. The fill volume per cycle in the embodiment of Figure 5 is reduced to an average of 2400 ml. The UF per cycle drops from 240 ml to 192 ml.

[0086] In method 100, assume that the first two cycles are performed as prescribed, consuming 6000 milliliters, leaving 6000 milliliters for the original final two cycles. A fifth cycle is added because the third cycle results in insufficient drainage. Method 100 in FIG. 3 teaches dividing the remaining 6000 milliliters by the remaining three cycles, resulting in 2000 milliliters per cycle. The example in FIG. 5 instead uses an average value of 2400 ml. In the example in FIG. 5, the final fill volume, assuming treatment continues after adding a single cycle, is then reduced to only 1,200 milliliters, the remaining amount of unused solution.

[0087] In the alternative method of FIG. 5, when the first cycle is added as shown in FIG. 6, using the new average fill volume per cycle and the new average UF per cycle, a new minimum discharge rate is calculated using the following formula:

number

[0088] 6 shows the worst case peritoneal volume scenario for a 64.8% minimum drainage volume treatment, i.e., each actual drainage exactly meets the 64.8% minimum drainage volume. As shown, the maximum peritoneal volume nevertheless exceeds the programmed limit of 4000 ml.

[0089] If the residual volume at the end of drain is still insufficient even after adding cycles using the alternative embodiment of Figures 5-7, the treatment is modified to use the same total unused fluid volume of 12000 ml for 6 cycles instead of 5. The average fill volume decreases to 2000 ml per cycle. The average UF per cycle drops from 192 ml to 160 ml.

[0090] The new minimum emission rate is again calculated using the following formula:

number

[0091] 7 shows the worst case peritoneal volume scenario for a 54% minimum drainage volume treatment using the method of the present invention, where each actual drainage exactly meets the 54% minimum drainage volume, yet the maximum peritoneal volume never exceeds the programmed limit of 4000 ml.

[0092] In Figures 5 to 7, the maximum residual peritoneal volume at the end of drainage increases from (i) 760 milliliters for 81% minimum drainage with a nominal fill volume of 3000 milliliters, (ii) 1,408 milliliters for 64.8% minimum drainage with a nominal fill volume of 2400 milliliters, to (iii) 1840 milliliters for 54% minimum drainage with a nominal fill volume of 2000 milliliters. The maximum allowable instantaneous peritoneal volume in all three cases is the same, i.e., 4000 milliliters. The method of Figures 5 to 7 can be implemented automatically, as in method 100, or by patient preference, as in method 150.

[0093] In the embodiments of Figures 5 to 7, the relationship between the maximum allowable instantaneous peritoneal capacity, the nominal or average filling volume per cycle, the UF per cycle, and the minimum discharge volume / rate can be characterized by the following equation, which provides proof that the peritoneal capacity at the end of dwell for the alternative embodiments of Figures 5 to 7 never exceeds the maximum peritoneal capacity.

[0094] The minimum drainage volume is a function of the fill volume, the cycle UF, and the residual volume remaining in the patient's peritoneum at the end of each drain. The minimum drainage rate is, for the alternative embodiment of Figures 5 to 7, (fill volume + cycle UF) / maximum peritoneal volume. Minimum drainage volume for each cycle = minimum drainage rate * (Fill volume + Cycle UF + Discharge residual volume before).

[0095] The proof is as follows.

[0096]

number

number

[0097] As seen in the above proof for the alternative embodiment of Figures 5 to 7, Min Drain % = (Fill Volume + Cycle UF) / Maximum Peritoneal Volume, so substituting Min Drain % in Equation 4 results in Patient Volume at the end of dwell n = Maximum Peritoneal Volume.

[0098] A further alternative method for controlling the minimum draining volume is to establish a maximum residual volume that can remain in the patient's peritoneal cavity before proceeding to the next fill. This volume is determined by: Maximum Residual Volume = Maximum Peritoneal Volume ("MPV") - (Filling Volume + Cycle UF). In this further alternative method, the estimated peritoneal volume at the end of each draining step is compared to the maximum residual volume, and if the estimated peritoneal volume is less than the maximum residual volume, the next fill can proceed without exceeding the MPV. For this further alternative method, the estimated peritoneal volume at the end of each draining step = (Σ Filling Volume (1 to N) + Σ Cycle UF (1 to N)) - Σ Draining Volume (1 to N).

[0099] (2. Tidal Therapy) 8-10, an embodiment of tidal therapy is illustrated. In one implementation, if a patient, clinician, or physician selects that the patient perform tidal therapy, machine 12 of system 10 queries, for example, via video monitor 20 and / or audio guidance via speaker 24, whether the patient would like to perform a "plus 1" tidal therapy or a "plus 2" tidal therapy. FIG. 8 illustrates a reference CCPD therapy used to calculate the "plus 1" tidal therapy of FIG. 9 and the "plus 2" tidal therapy of FIG. 10.

[0100] The tidal therapy of the present disclosure can be entered as a CCPD therapy, which is generally easier to perform. In fact, it is contemplated to start with a stored CCPD therapy that can be performed alternatively as a CCPD therapy if selected in CCPD versus a tidal therapy screen on the video monitor 20. However, if a preferred CCPD therapy is selected to be performed instead of being performed as a tidal therapy, the machine 12 of the system 10 prompts the patient, clinician, or caregiver to select either "plus 1" or "plus 2" to indicate that one additional cycle will be added to the selected CCPD therapy, or that two additional cycles will be added to the selected CCPD therapy. In one embodiment, regardless of whether a "plus 1" or "plus 2" tidal therapy is selected, (i) the total treatment time is kept constant with the time of the selected CCPD therapy, (ii) the same total volume of unused dialysate prescribed for the CCPD therapy is delivered to the patient during the course of the fill phase, (iii) the patient is filled to the same volume after each fill as is performed with the selected CCPD therapy, and (iv) the total treatment duration is kept constant with the duration of the selected CCPD therapy.

[0101] FIG. 8 illustrates a CCPD regimen that the patient, clinician, or physician selects to modify to tidal regimen and is displayed on the display device 20 of the machine 12 of the system 10. If the patient performs the CCPD regimen of FIG. 8 instead of tidal regimen, the last fill of the previous day or the daytime fill takes about 30 minutes to drain completely. Then, in each case, there are four cycles in which the patient fills up to 2,500 milliliters, thus using 10,000 milliliters throughout the treatment. Each cycle, including the fill, dwell, and full drain phases, lasts about two hours and fifteen minutes (135 minutes), leading to a total treatment time of about nine hours (540 minutes). If the expected UF (e.g., 8% of the fill volume) is removed during each dwell cycle, the patient's maximum instantaneous intraperitoneal volume is about 2,700 milliliters at the end of each dwell phase. At the end of the drain phase for the fourth cycle, the patient is given a final fill of the day of 2,000 milliliters (or until a daytime exchange is performed).

[0102] In one embodiment, the patient, clinician, or physician can choose to add either one or two additional cycles to a selected CCPD regimen. FIG. 9 illustrates an example when a single cycle is added. As shown, the system 10 converts the CCPD cycle of FIG. 8 to the tidal regimen of FIG. 9, shortening each of the first, second, third, and fourth drains to leave a 25 percent residual volume for each of the second, third, fourth, and fifth cycles. The fifth drain phase completely drains the patient. The machine 12, in one embodiment, wakes the patient during or at the end of the fifth or final drain phase so that the patient can move around, sit upright, or do whatever maneuvers will help completely drain the patient.

[0103] A typical drainage phase curve for a patient shows a linear change in volume, similar to the downwardly extending line of the drainage phase illustrated in Figures 8 to 10. At the drainage transition point, the volume profile becomes non-linear, decelerating visibly and forming a downwardly sloping parabolic curve that asymptotically approaches complete drainage. This phenomenon is shown and explained in detail in co-pending U.S. patent application Ser. No. 12 / 389,886, entitled "Simulation of Patent Drain Phase in Peritoneal Dialysis," filed Feb. 20, 2009, the entire contents of which are incorporated herein by reference.

[0104] For the tidal therapy of Figure 9, the prescribed 25 percent residual volume of fluid allowed to remain in the patient's peritoneum means that the patient drains 75 percent of the fill volume (including any unused dialysate or residual volume plus previous residual drainage), and it is desired to stop drainage before the patient transitions from efficient linear drainage to the less effective parabolic drainage. Thus, the drainage of Figure 9 attempts to be efficient all the way up to the 25 percent residual volume.

[0105] If the patient finds that they are unable to meet the 25 percent residual drain capacity on a sufficiently consistent basis, for example, the patient transitions to a less efficient non-linear drain before draining 75 percent of the fill volume, the patient, clinician, or physician can instead select the selected CCPD regimen plus two additional cycles as shown in FIG. 10. A "plus 2" cycle regimen can set the patient's residual drain capacity to be 40 percent of the fill volume (including unused dialysate, or residual volume plus previous residual drains). In either the "plus 1" or "plus 2" tidal regimen, the system 10 advantageously allows the tidal regimen to be automatically set in memory from the selected CCPD regimen, as opposed to requiring the patient, clinician, or physician to input all details of the tidal regimen.

[0106] In Figure 9, after the last fill of the previous day or the initial drain of a midday exchange, which again takes approximately 30 minutes, the first fill is a full fill to 2,500 milliliters as set by the selected CCPD regimen. As one additional cycle is added to the treatment of Figure 9 for a total of 5, each cycle is reduced in duration to 108 minutes, resulting in a total treatment time of 9 hours (540 minutes) the same as the selected CCPD regimen.

[0107] The drain phase for each of the first, second, third, and fourth cycles is shortened to leave 625 milliliters (25% of the total volume at the end of the 2,500 milliliter initial fill and each subsequent fill) in the patient's peritoneal cavity. Each of the second, third, fourth, and fifth fills is then shortened to 1,875 milliliters, resulting in the same initial intraperitoneal fill volume of 2,500 milliliters, which is consistent with each of the fills of the selected CCPD regimen of FIG. 8. A total treatment volume of 10,000 milliliters (2,500 + 4 x 1,875), which is also the same as the total amount of unused fluid delivered to the patient in the selected CCPD regimen, is delivered to the patient during the five cycles.

[0108] In Figure 10, after the initial drain of the last fill or midday exchange of the previous day, which again takes approximately 30 minutes, the first fill is a full fill to 2,500 milliliters as set by the selected CCPD regimen. Now two additional cycles are added to the treatment of Figure 10 for a total of six, so each cycle is reduced in duration to 90 minutes, resulting in a total treatment time of nine hours (540 minutes), the same as the selected CCPD regimen.

[0109] The drain phase during each of the first, second, third, fourth, and fifth cycles is shortened to leave 1000 milliliters (40% of the total volume at the end of the 2,500 milliliter initial fill and each subsequent fill) in the patient's peritoneal cavity. Each of the second, third, fourth, fifth, and sixth fills is then shortened to 1,500 milliliters, resulting in the same initial intraperitoneal fill volume of 2,500 milliliters, which is consistent with each of the fills of the selected CCPD regimen of FIG. 8. A total treatment volume of 10,000 milliliters (2,500 + 5 x 1,500), which is also the same as the total amount of unused fluid delivered to the patient in the selected CCPD regimen of FIG. 8, is delivered to the patient during the six cycles.

[0110] The tidal therapy methods of the present disclosure are not limited to the "plus 1" or "plus 2" methods discussed herein. Instead, three or more cycles can be added.

[0111] In the typical CCPD method, care should be taken to ensure that large amounts of unused solution do not result. It is intended to use the 85% rule to calculate the initial overnight cycle number that consumes all fluid, where number of CCPD cycles = total overnight treatment volume / overnight fill volume per cycle. If the result is not evenly divided, the remainder is examined and if the remainder is ≧0.85, the treatment is rounded up to the next cycle number, if the remainder is <0.85, the number of cycles is rounded down.

[0112] In the example, if the total overnight treatment volume = 10,000 milliliters and the desired fill volume per cycle is 2,500 milliliters, then 10,000 / 2500 = 4 cycles with no remainder, and therefore no solution was wasted. If instead the desired fill volume per cycle is 2600 milliliters rather than 2500, the same algorithm would result in 10,000 / 2600 = 3.846, and since 0.846 < 0.85, the result would be rounded down to 3 cycles. The total overnight treatment volume actually used would then be 2600 milliliters x 3 cycles = 7,800 milliliters, with 2,200 milliliters of the desired 10,000 milliliters not being used.

[0113] However, the 2600 ml regimen can be converted to a tidal regimen as in Figures 8 to 10 with the result that all the solution is used. For the plus 1 regimen, for example, there are a total of 4 cycles. 10,000 ml - 2,600 ml (initial full fill) = 7400 ml / remaining 3 cycles = 2467 ml in the remaining 3 cycles, resulting in a tidal rate of 98% and a patient residual volume of only 33 ml, a suboptimal treatment due to the high tidal rate. The plus 2 tidal regimen according to Figures 8 to 10 would be more optimal, resulting in a tidal rate of 7400 ml / remaining 4 cycles = 1850 ml, a tidal rate of 71%, and a corresponding patient residual volume of 750 ml, with all the solution volume being used.

[0114] Thus, the methods of Figures 8-10 allow for selection between several optimal therapies, for example, to determine an optimal therapy given a desired fill volume. The tidal therapy systems and methods of Figures 8-10 also allow the clinician to gradually increase the fill volume, for example, from 2000 milliliters per cycle to 2100 milliliters to 2200 milliliters, without changing the total nighttime treatment volume and without wasting solution.

[0115] Aspects of the Disclosure Aspects of the subject matter described herein may be useful alone or in combination with one or more other aspects described herein. Without limiting the above description, according to a first aspect of the present disclosure, a system for performing peritoneal dialysis therapy includes at least one dialysate pump and a control unit operable with the at least one dialysate pump to perform a plurality of peritoneal dialysis cycles, the cycles including a filling phase, a dwell phase, and a drain phase, and the control unit is configured to: (i) prevent a maximum peritoneal volume from being exceeded after any of the dwell phases of a plurality of patient cycles; (ii) ensure that the total amount of dialysate volume of the filling phase as prescribed is delivered to the patient; and (iii) if it is determined that the residual volume left in the patient after one of the drain phases causes (i) to be violated during the next cycle, reduce the amount of dialysate volume of the filling phase of the next cycle and add an additional cycle to the peritoneal dialysis therapy so that (ii) is satisfied.

[0116] According to a second aspect of the disclosure, which may be used in combination with the first aspect, for the first cycle, satisfying (i) includes ensuring that the prescribed loading volume plus the expected ultrafiltration volume per cycle is less than the maximum peritoneal volume.

[0117] According to a third aspect of the present disclosure, which may be used in combination with any one or more of the preceding aspects, satisfying (i) includes ensuring that the fill volume plus the expected ultrafiltration volume per cycle plus the remaining residual volume of fluid from the previous drainage step is less than the maximum peritoneal volume.

[0118] According to a fourth aspect of the present disclosure, which may be used in combination with the third aspect, the expected ultrafiltration capacity is a percentage of the prescribed fill stage fluid volume.

[0119] According to a fifth aspect of the present disclosure, which may be used in combination with any one or more of the preceding aspects, the control unit in (iii) is configured to reduce the amount of dialysate volume for each of the remaining filling stages.

[0120] According to a sixth aspect of the present disclosure, which may be used in combination with any one or more of the preceding aspects, the control unit in (iii) is configured to reduce the amount of dialysis fluid volume in each of the remaining filling stages by the same amount.

[0121] According to a seventh aspect of the present disclosure, which may be used in combination with any one or more of the preceding aspects, the control unit in (iii) is configured to reduce the amount of dialysate volume for each of the remaining filling stages to an amount equal to a remainder of the total dialysate volume divided by the number of remaining cycles including the additional cycle.

[0122] According to an eighth aspect of the present disclosure, which may be used in combination with the seventh aspect, the control unit is further configured to vary the minimum drainage rate to a reduced fill volume plus an expected ultrafiltration capacity per cycle, resulting in the result being divided by the maximum peritoneal capacity.

[0123] According to a ninth aspect of the present disclosure, which may be used in combination with any one or more of the preceding aspects, the control unit is configured to perform (iii) multiple times if necessary.

[0124] According to a tenth aspect of the present disclosure, which may be used in combination with any one or more of the preceding aspects, the control unit in (iii) is configured to (a) reduce the amount of dialysate volume in each of the remaining filling stages to an amount equal to a first remaining fraction of the total dialysate volume divided by the remaining number of cycles including the first additional cycle, and, if necessary, (b) reduce the amount of dialysate volume in each of the remaining filling stages to an amount equal to a second remaining fraction of the total dialysate volume divided by the remaining number of cycles including the second additional cycle.

[0125] According to an eleventh aspect of the present disclosure, which may be used in combination with the tenth aspect, the control unit is further configured to (c) change, a first time, the minimum drainage rate in (a) to a first amount plus an expected ultrafiltration volume that results in a first result divided by the maximum peritoneal volume, and (d) change, a second time, the minimum drainage rate in (b) to a second amount plus an expected ultrafiltration volume that results in a second result divided by the maximum peritoneal volume.

[0126] According to a twelfth aspect of the present disclosure, which may be used in combination with the eleventh aspect, the expected ultrafiltration capacity in (c) differs from the expected ultrafiltration capacity in (d) by a first amount that differs from the second amount.

[0127] According to a thirteenth aspect of the present disclosure, which may be used in combination with any one or more of the preceding aspects, the control unit is further configured to reduce the duration of the dwell phase in the next cycle.

[0128] According to a fourteenth aspect of the present disclosure, which may be used in combination with any one or more of the preceding aspects, the control unit is further configured to perform (i), (ii), and (iii) based on a user selection of performing continuous cyclic peritoneal dialysis therapy as opposed to tidal dialysis therapy.

[0129] According to a fifteenth aspect of the present disclosure, which may be used in combination with any one or more of the preceding aspects, the control unit is configured to perform (iii) based on a user selection to modify the originally prescribed peritoneal dialysis therapy, or automatically perform (iii).

[0130] According to a sixteenth aspect of the present disclosure, which may be used in combination with any one or more of the preceding aspects, a system for performing peritoneal dialysis therapy includes at least one dialysate pump and a control unit operable with the at least one dialysate pump to perform a plurality of peritoneal dialysis cycles, the cycles including a fill phase, a dwell phase, and a drain phase, the control unit configured to (i) ensure that a total of the prescribed fill phase dialysate volume is delivered to the patient, and (ii) if a minimum drainage rate cannot be achieved after one of the drain phases, reduce the amount of the fill phase dialysate volume of the next cycle and add an additional cycle to the peritoneal dialysis therapy such that (i) is satisfied.

[0131] According to a seventeenth aspect of the present disclosure, which may be used in combination with the sixteenth aspect and with any one or more of the preceding aspects, the control unit in (ii) is configured to reduce the amount of dialysis fluid volume for each of the remaining filling stages.

[0132] According to an eighteenth aspect of the present disclosure, which may be used in combination with the seventeenth aspect and with any one or more of the preceding aspects, the control unit in (ii) is configured to reduce the amount of dialysate volume for each of the remaining filling stages to an amount equal to a remaining portion of the total dialysate volume divided by the remaining number of cycles including the additional cycle.

[0133] According to a nineteenth aspect of the present disclosure, which may be used in combination with the sixteenth aspect and with any one or more of the preceding aspects, the control unit is further configured to vary the minimum drainage rate to a reduced filling volume plus an expected volume of expected ultrafiltration, resulting in the volume being divided by the maximum peritoneal capacity.

[0134] According to a twentieth aspect of the present disclosure, which may be used in combination with the sixteenth aspect and with any one or more of the preceding aspects, the control unit is further configured to reduce the duration of the dwell phase in the next cycle.

[0135] According to a twenty-first aspect of the present disclosure, which may be used in combination with the sixteenth aspect and with any one or more of the preceding aspects, the control unit is further configured to perform (i) and (ii) based on a user selection of performing continuous cyclic peritoneal dialysis therapy as opposed to tidal dialysis therapy.

[0136] According to a twenty-second aspect of the present disclosure, which may be used in combination with the sixteenth aspect and with any one or more of the preceding aspects, the control unit is configured to perform (ii) based on a user selection to modify an originally prescribed peritoneal dialysis therapy, or to perform (ii) automatically based on settings pre-configured by a clinician.

[0137] According to a twenty-third aspect of the present disclosure, which may be used in combination with any one or more of the preceding aspects, a system for performing peritoneal dialysis includes at least one dialysis fluid pump and a control unit operable with the at least one dialysis fluid pump to perform a plurality of peritoneal dialysis cycles, the cycles including a fill phase, a dwell phase, and a drain phase, the control unit configured to (i) ensure that a maximum peritoneal capacity is not exceeded at the end of each cycle's dwell phase, (ii) ensure that the entire prescribed dialysis fluid volume is delivered to the patient over the fill phase of the cycle, and (iii) monitor each drain phase to ensure that a minimum drain volume is met, and if not, shorten a subsequent fill phase to comply with (i) and add a cycle to comply with (ii).

[0138] According to a twenty-fourth aspect of the present disclosure, which may be used in combination with the twenty-third aspect and with any one or more of the preceding aspects, the system includes a total prescription time for the cycle in total, and the control unit is further configured to reduce the duration of at least one subsequent dwell phase if a cycle is added in (iii).

[0139] According to a twenty-fifth aspect of the present disclosure, which may be used in combination with the twenty-third aspect and with any one or more of the preceding aspects, the control unit is further configured to perform (i), (ii), and (iii) based on an initial user selection of performing continuous cyclic peritoneal dialysis therapy as opposed to tidal dialysis therapy.

[0140] According to a twenty-sixth aspect of the present disclosure, which may be used in combination with the twenty-third aspect and with any one or more of the preceding aspects, the control unit is configured to perform (iii) based on a user selection to modify the originally prescribed peritoneal dialysis therapy.

[0141] According to a twenty-seventh aspect of the present disclosure, which may be used in combination with the twenty-third aspect and with any one or more of the preceding aspects, the minimum drainage volume is the maximum peritoneal volume - (filling phase volume + expected ultrafiltrate volume per cycle).

[0142] According to a twenty-eighth aspect of the present disclosure, which may be used in combination with any one or more of the preceding aspects, a system for performing peritoneal dialysis therapy includes at least one dialysate pump and a control unit operable with the at least one dialysate pump to perform a plurality of peritoneal dialysis cycles, the cycles including a fill phase, a dwell phase, and a drain phase, the control unit configured to (i) store a previously entered continuous cyclic peritoneal dialysis ("CCPD") therapy having a total prescribed fresh dialysis fluid fill volume delivered during n cycles, the cycles occurring for a full treatment duration, and (ii) automatically convert the CCPD therapy to a tidal peritoneal dialysis therapy having n+1 cycles, using a total prescribed fresh dialysis fluid fill volume, and maintaining a full treatment duration.

[0143] According to a twenty-ninth aspect of the present disclosure, which may be used in combination with the twenty-eighth aspect and with any one or more of the preceding aspects, the control unit is configured to provide an option to perform (ii), in which the tidal therapy is a first tidal therapy, or alternatively, an option to perform (iii), in which the CCPD therapy is automatically converted to a second tidal therapy having n+2 cycles, using the entire prescription-free dialysis fluid fill volume, and maintaining the entire treatment duration.

[0144] According to a 30th aspect of the present disclosure, which may be used in combination with the 29th aspect and with any one or more of the preceding aspects, a first tidal therapy has a prescribed first residual drainage capacity and a second tidal therapy has a prescribed second, higher residual drainage capacity.

[0145] According to a thirty-first aspect of the present disclosure, which may be used in combination with the twenty-eighth aspect and with any one or more of the preceding aspects, the control unit is further configured to perform (i) and (ii) based on a user's selection of performing tidal therapy peritoneal dialysis as opposed to CCPD dialysis therapy.

[0146] According to a thirty-second aspect of the present disclosure, which may be used in combination with the twenty-eighth aspect and with any one or more of the preceding aspects, the control unit is further configured such that a volume present in the patient after each tidal therapy filling is at least substantially equal to a volume present in the patient after each CCPD therapy filling.

[0147] According to a thirty-third aspect of the present disclosure, any of the structures and functionality illustrated and described in connection with FIG. 1 may be used in combination with any one or more of the preceding aspects.

[0148] According to a thirty-fourth aspect of the present disclosure, any of the structures and functionality illustrated and described in connection with FIG. 2 may be used in combination with any one or more of the preceding aspects.

[0149] According to a thirty-fifth aspect of the present disclosure, any of the structures and functionality illustrated and described in connection with FIG. 3 may be used in combination with any one or more of the preceding aspects.

[0150] According to a thirty-sixth aspect of the present disclosure, any of the structures and functionality illustrated and described in connection with FIG. 4 may be used in combination with any one or more of the preceding aspects.

[0151] According to a thirty-seventh aspect of the present disclosure, any of the structures and functionality illustrated and described in connection with FIG. 5 may be used in combination with any one or more of the preceding aspects.

[0152] According to a thirty-eighth aspect of the present disclosure, any of the structures and functionality illustrated and described in connection with FIG. 6 may be used in combination with any one or more of the preceding aspects.

[0153] According to a thirty-ninth aspect of the present disclosure, any of the structures and functionality illustrated and described in connection with FIG. 7 may be used in combination with any one or more of the preceding aspects.

[0154] According to a fortieth aspect of the present disclosure, any of the structures and functionality illustrated and described in connection with FIG. 8 may be used in combination with any one or more of the preceding aspects.

[0155] According to a forty-first aspect of the present disclosure, any of the structures and functionality illustrated and described in connection with FIG. 9 may be used in combination with any one or more of the preceding aspects.

[0156] According to a forty-second aspect of the present disclosure, any of the structures and functionality illustrated and described in connection with FIG. 10 may be used in combination with any one or more of the preceding aspects.

[0157] It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present subject matter and without diminishing its intended advantages. Accordingly, such changes and modifications are intended to be encompassed within the scope of the appended claims.

[0158] For example, the present invention provides the following: (Item 1) 1. A system for performing peritoneal dialysis therapy, comprising: The system comprises: at least one dialysate pump; Control unit and Equipped with The control unit is operable with the at least one dialysate pump to perform a plurality of peritoneal dialysis cycles, the peritoneal dialysis cycles including a fill phase, a dwell phase, and a drain phase, the control unit further comprising: (i) avoiding the maximum peritoneal capacity being exceeded after any of the dwell phases of multiple peritoneal dialysis cycles; (ii) ensuring that the prescribed total dialysate volume for the fill phase is delivered to the patient; and (iii) if (i) is determined to be violated during a next cycle due to a residual volume left in the patient after one of the drain phases, reducing the amount of dialysate volume in the fill phase of the next cycle and adding an additional cycle to the peritoneal dialysis therapy such that (ii) is satisfied; A system configured to: (Item 2) 2. The system for performing peritoneal dialysis therapy of item 1, wherein for the first cycle, satisfying (i) includes ensuring that the prescribed fill volume plus the expected ultrafiltration volume per cycle is less than the maximum peritoneal volume. (Item 3) 2. The system for performing peritoneal dialysis therapy described in item 1, wherein satisfying (i) includes ensuring that the fill volume plus the expected ultrafiltration volume per cycle plus the residual volume of fluid remainder from the previous drain phase is less than the maximum peritoneal volume. (Item 4) 4. The system for performing peritoneal dialysis therapy according to item 3, wherein the expected ultrafiltration volume is a percentage of the dialysate volume of the filling stage as prescribed. (Item 5) 2. The system for performing peritoneal dialysis therapy described in item 1, wherein the control unit in (iii) is configured to reduce the amount of the dialysate volume for each of the remaining filling stages. (Item 6) 2. The system for performing peritoneal dialysis therapy described in item 1, wherein the control unit in (iii) is configured to reduce the amount of the dialysate volume for each of the remaining filling stages by the same amount. (Item 7) 2. The system for performing peritoneal dialysis therapy described in item 1, wherein the control unit in (iii) is configured to reduce the amount of the dialysate volume for each of the remaining filling stages to an amount equal to a remaining fraction of the total dialysate volume divided by the number of remaining cycles including the additional cycle. (Item 8) 8. The system for performing peritoneal dialysis therapy described in item 7, wherein the control unit is further configured to change the minimum drainage rate to the reduced fill volume plus an expected ultrafiltration volume per cycle divided by the maximum peritoneal volume. (Item 9) 2. The system for performing peritoneal dialysis therapy described in item 1, wherein the control unit is configured to perform (iii) multiple times, if necessary. (Item 10) 2. The system for performing peritoneal dialysis therapy described in item 1, wherein the control unit in (iii) is configured to: (a) reduce the amount of the dialysate volume in each of the remaining filling stages to a first amount, the first amount being equal to a first remaining portion of the total dialysate volume divided by the number of remaining cycles including the additional cycle; and, if necessary, (b) reduce the amount of the dialysate volume in each of the remaining filling stages to a second amount, the second amount being equal to a second remaining portion of the total dialysate volume divided by the number of remaining cycles including the second added cycle. (Item 11) 11. The system for performing peritoneal dialysis therapy described in Item 10, wherein the control unit is further configured to: (c) change the minimum drainage rate a first time to a first volume obtained by adding an expected ultrafiltration volume to the first amount in (a) divided by the maximum peritoneal volume; and (d) change the minimum drainage rate a second time to a second volume obtained by adding an expected ultrafiltration volume to the second amount in (b) divided by the maximum peritoneal volume. (Item 12) Item 12. The system for performing peritoneal dialysis therapy of item 11, wherein the expected ultrafiltration capacity in (c) differs from the expected ultrafiltration capacity in (d) due to the first amount of reduction being different from the second amount of reduction. (Item 13) 2. The system for performing peritoneal dialysis therapy described in item 1, wherein the control unit is further configured to shorten the duration of the dwell phase in the next cycle. (Item 14) 2. The system for performing peritoneal dialysis therapy described in item 1, wherein the control unit is further configured to perform (i), (ii), and (iii) based on a user selection to perform continuous cyclic peritoneal dialysis therapy as opposed to tidal dialysis therapy. (Item 15) 2. The system for performing peritoneal dialysis therapy described in item 1, wherein the control unit is configured to perform (iii) or to automatically perform (iii) based on a user selection to modify the originally prescribed peritoneal dialysis therapy. (Item 16) 1. A system for performing peritoneal dialysis therapy, comprising: The system comprises: at least one dialysate pump; Control unit and Equipped with The control unit is operable with the at least one dialysate pump to perform a plurality of peritoneal dialysis cycles, the peritoneal dialysis cycles including a fill phase, a dwell phase, and a drain phase, the control unit further comprising: (i) ensuring that the prescribed total amount of dialysate volume for the fill phase is delivered to the patient; (ii) if a minimum drainage rate cannot be achieved after one of the drain phases, reducing the amount of the dialysate volume of the fill phase of a next cycle and adding an additional cycle to the peritoneal dialysis therapy such that (i) is satisfied; A system configured to: (Item 17) 17. The system for performing peritoneal dialysis therapy of claim 16, wherein the control unit in (ii) is configured to reduce the amount of the dialysate volume for each of the remaining filling stages. (Item 18) 18. The system for performing peritoneal dialysis therapy described in item 17, wherein the control unit in (ii) is configured to reduce the amount of the dialysate volume for each of the remaining filling stages to an amount equal to the remaining portion of the total dialysate volume divided by the number of remaining cycles including the added cycle. (Item 19) Item 17. The system for performing peritoneal dialysis therapy described in item 16, wherein the control unit is further configured to change the minimum drainage rate to the reduced filling volume plus the expected amount of ultrafiltration divided by the maximum peritoneal capacity. (Item 20) Item 17. The system for performing peritoneal dialysis therapy of item 16, wherein the control unit is further configured to reduce the duration of the dwell phase in the next cycle. (Item 21) 17. The system for performing peritoneal dialysis therapy described in item 16, wherein the control unit is further configured to perform (i) and (ii) based on a user selection of performing continuous cyclic peritoneal dialysis therapy as opposed to tidal dialysis therapy. (Item 22) 17. A system for performing peritoneal dialysis therapy as described in item 16, wherein the control unit is configured to perform (ii) based on a user selection to modify an originally prescribed peritoneal dialysis therapy, or to perform (ii) automatically based on settings pre-configured by a clinician. (Item 23) 1. A system for performing peritoneal dialysis, comprising: The system comprises: at least one dialysate pump; Control unit and Equipped with The control unit is operable to perform a plurality of peritoneal dialysis cycles with the at least one dialysate pump, the peritoneal dialysis cycles including a fill phase, a dwell phase, and a drain phase, the control unit further comprising: (i) ensuring that at the end of the retention phase of each cycle, the maximum peritoneal volume is not exceeded; (ii) ensuring that the prescribed total amount of dialysate volume is delivered to the patient over the fill phase of the cycle; and (iii) monitoring each discharge step to ensure that the minimum discharge volume is met, and if not, shortening subsequent fill steps to comply with (i) and adding cycles to comply with (ii); A system configured to: (Item 24) 24. The system for performing peritoneal dialysis therapy of claim 23, further comprising a total prescribed time for the entirety of the cycle, the control unit being further configured to reduce a duration of at least one subsequent dwell phase if a cycle is added in (iii). (Item 25) 24. The system for performing peritoneal dialysis therapy described in item 23, wherein the control unit is further configured to perform (i), (ii), and (iii) based on an initial user selection of performing continuous cyclic peritoneal dialysis therapy as opposed to tidal dialysis therapy. (Item 26) 24. The system for performing peritoneal dialysis therapy described in item 23, wherein the control unit is configured to perform (iii) based on a user selection to modify the originally prescribed peritoneal dialysis therapy. (Item 27) 24. The system for performing peritoneal dialysis therapy according to item 23, wherein the minimum drain volume is the maximum peritoneal volume minus the fill stage volume plus the expected ultrafiltrate volume per cycle. (Item 28) 1. A system for performing peritoneal dialysis therapy, comprising: The system comprises: at least one dialysate pump; Control unit and Equipped with The control unit is operable to perform a plurality of peritoneal dialysis cycles with the at least one dialysate pump, the cycles including a fill phase, a dwell phase, and a drain phase, the control unit further comprising: (i) storing a previously entered continuous cyclic peritoneal dialysis ("CCPD") regimen, the CCPD regimen having a total prescription fresh dialysate fill volume delivered over n cycles, the cycles occurring over a full treatment duration; (ii) automatically converting the CCPD therapy to a tidal peritoneal dialysis therapy having n+1 cycles, utilizing the entire prescription unused dialysis fill volume, and maintaining the entire treatment duration; A system configured to: (Item 29) 29. The system for performing peritoneal dialysis therapy described in Item 28, wherein the control unit is configured to provide the option of performing (ii) wherein the tidal therapy is a first tidal therapy, or alternatively performing (iii) wherein the CCPD therapy is automatically converted to a second tidal therapy, the second tidal therapy having n+2 cycles, using the entire prescription unused dialysis fluid fill volume, and maintaining the entire treatment duration. (Item 30) 30. The system for performing peritoneal dialysis therapy of item 29, wherein the first tidal therapy has a prescribed first residual drainage volume and the second tidal therapy has a prescribed second, higher residual drainage volume. (Item 31) 30. The system for performing peritoneal dialysis therapy described in item 28, wherein the control unit is further configured to perform (i) and (ii) based on a user's selection of performing tidal therapy peritoneal dialysis as opposed to CCPD dialysis therapy. (Item 32) 29. The system for performing peritoneal dialysis therapy described in item 28, wherein the control unit is further configured such that a volume present in the patient after each of the tidal therapy fills is at least substantially equal to a volume present in the patient after each of the CCPD therapy fills.

Claims

1. A dialysis treatment device comprising: at least one dialysate pump; and a control unit operable to perform a plurality of peritoneal dialysis cycles during a dialysis treatment of a patient using the at least one dialysis fluid pump, the peritoneal dialysis cycles including a fill phase, a dwell phase and a drain phase, the control unit comprising: storing a peritoneal dialysis therapy prescription specifying parameters for the dialysis therapy, the parameters including at least (a) a prescribed total fresh dialysate fill volume and (b) a desired fill volume per cycle; determining the number of cycles n to be performed by dividing the prescribed total fresh dialysate fill by the desired fill per cycle, the remainder of the division corresponding to an expected amount of unused fresh dialysate that will not be used; determining an expected volume of unused dialysate based on the remainder determined by dividing the prescribed total fresh dialysate fill by the desired fill per cycle; determining a tidal peritoneal dialysis therapy prescription having n+1 cycles that uses at least a portion of the unused dialysate if the expected amount of unused dialysate is greater than a specified amount; displaying an option to select the tidal peritoneal dialysis therapy prescription having n+1 cycles or the stored peritoneal dialysis therapy prescription; The dialysis treatment device is configured to:

2. 10. The dialysis treatment device of claim 1, wherein the peritoneal dialysis therapy prescription comprises a continuous cyclic peritoneal dialysis ("CCPD") therapy.

3. The control unit: comparing the remainder determined by dividing the prescribed total fresh dialysate fill by the desired fill per cycle to a specified threshold; if the remainder is greater than or equal to the specified threshold, rounding up the determined number of cycles to an integer number of cycles; 10. The dialysis treatment machine of claim 1, further configured to:

4. 4. The dialysis treatment machine of claim 3, wherein the specified threshold is 0.

85.

5. The dialysis treatment machine of claim 3 , wherein the control unit determines the tidal peritoneal dialysis therapy prescription having n+1 cycles if the remainder is less than the specified threshold.

6. 10. The dialysis treatment machine of claim 1, wherein the desired fill volume per cycle is configured to increase incrementally from cycle to cycle.

7. the tidal peritoneal dialysis therapy prescription having n+1 cycles is a first tidal peritoneal dialysis therapy prescription, and the control unit: if the expected amount of unused fresh dialysate is greater than the specified volume, determining a second tidal peritoneal dialysis therapy prescription having n+2 cycles that uses more of the unused fresh dialysate than the first tidal peritoneal dialysis therapy prescription; causing an additional option to be displayed for selecting said second tidal peritoneal dialysis therapy prescription having n+2 cycles; 10. The dialysis treatment machine of claim 1 further configured to:

8. 8. The dialysis treatment machine of claim 7, wherein the first or second tidal peritoneal dialysis therapy prescription is set to maintain a total treatment duration.

9. 8. The dialysis treatment machine of claim 7, wherein the first tidal peritoneal dialysis therapy prescription has a prescribed first residual drainage volume and the second tidal peritoneal dialysis therapy prescription has a larger prescribed second residual drainage volume.

10. 8. The dialysis treatment machine of claim 7, wherein the control unit is further configured to ensure that an amount remaining within the patient after each fill of the first or second tidal peritoneal dialysis therapy prescription is at least substantially equal to an amount that would remain within the patient after each fill of the stored peritoneal dialysis therapy prescription.

11. 8. The dialysis treatment machine of claim 7, wherein the control unit is configured to reduce individual drain times of at least some of the drain phases of at least one of the first and second tidal peritoneal dialysis therapy prescriptions to leave a specified amount of residual dialysate in the patient for the at least some of the drain phases.

12. 2. The dialysis treatment device of claim 1, wherein the control unit is configured to convert the stored peritoneal dialysis therapy prescription to the first or second tidal peritoneal dialysis therapy prescription using a maximum intraperitoneal volume of the patient stored for the stored peritoneal dialysis therapy prescription.

13. 10. The dialysis treatment machine of claim 1, wherein the peritoneal dialysis therapy prescription is configured to be entered into the control unit by a clinician or received by the control unit from a remote computer via a network connection.

14. 2. The dialysis treatment machine of claim 1, wherein the control unit is configured to cause the option to be displayed for selecting the tidal peritoneal dialysis therapy prescription having n+1 cycles or the stored peritoneal dialysis therapy prescription, and to provide information indicating which option is more optimal.

15. A dialysis treatment method comprising: storing, by the control unit, a peritoneal dialysis therapy prescription specifying parameters for dialysis treatment of the patient, the parameters including (a) a prescribed total fill volume of fresh dialysate to be delivered and (b) a desired fill volume per cycle, the peritoneal dialysis cycle including at least a fill phase, a dwell phase, and a drain phase; determining, by the control unit, the number of cycles n to be performed by dividing the prescribed total fresh dialysate fill by the desired fill per cycle, the remainder of the division corresponding to an expected amount of unused fresh dialysate that will not be used; determining, by the control unit, an expected volume of unused dialysate based on the remainder determined by dividing the prescribed total fresh dialysate fill by the desired fill volume per cycle; If the expected amount of unused fresh dialysate is greater than a specified amount, determining, by the control unit, a tidal peritoneal dialysis therapy prescription having n+1 cycles that uses at least a portion of the unused fresh dialysate; causing the control unit to display an option for selecting the tidal peritoneal dialysis therapy prescription having n+1 cycles or the stored peritoneal dialysis therapy prescription; operating, by the control unit, at least one dialysate pump according to the tidal peritoneal dialysis therapy prescription having n+1 cycles or the stored peritoneal dialysis therapy prescription based on the selected option; A dialysis treatment method comprising:

16. comparing, by the control unit, the remainder determined by dividing the prescribed total fresh dialysate fill by the desired fill per cycle to a specified threshold; if the remainder is greater than or equal to the specified threshold, rounding up the determined number of cycles to an integer number of cycles by the control unit; The dialysis treatment method of claim 15, further comprising:

17. 17. The dialysis treatment method of claim 16, further comprising determining the tidal peritoneal dialysis therapy prescription to have n+1 cycles if the remainder is less than the specified threshold.

18. the tidal peritoneal dialysis therapy prescription having n+1 cycles is a first tidal peritoneal dialysis therapy prescription, and the method comprises: if the expected amount of unused fresh dialysate is greater than the specified amount, determining, by the control unit, a second tidal peritoneal dialysis therapy prescription having n+2 cycles that uses more of the unused fresh dialysate than the first tidal peritoneal dialysis therapy prescription; causing the control unit to display an additional option for selecting the second tidal peritoneal dialysis therapy prescription having n+2 cycles; The dialysis treatment method of claim 15, further comprising:

19. 16. The dialysis treatment method of claim 15, wherein the peritoneal dialysis therapy prescription is entered by a clinician or received from a remote computer via a network connection.

20. The dialysis treatment method of claim 15, further comprising causing the control unit to display the option to select the tidal peritoneal dialysis therapy prescription having n+1 cycles or the stored peritoneal dialysis therapy prescription, and providing information indicating which option is more optimal.

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