An automated peritoneal dialysis system including an enhanced pressure detection function

Abstract

The medical fluid system includes a medical fluid pump actuator, a medical fluid transfer set having a flexible sheet, a temperature sensor positioned and arranged to sense a temperature of medical fluid flowing through the medical fluid transfer set, and a pressure sensor positioned and arranged to contact the flexible sheet when the medical fluid transfer set is loaded for operation by the medical fluid pump actuator, and a control unit configured to (i) precondition the flexible sheet for operation with the pressure sensor by causing the medical fluid pump actuator to apply pressure to the flexible sheet, and use the output from the temperature sensor in a compensation algorithm that modifies the output from the pressure sensor.

Description

Technical Field

[0001] (Priority Claim) This application claims the benefit and priority of U.S. Provisional Patent Application No. 63 / 185,050, filed May 6, 2021, entitled "Automated Peritoneal Dialysis Assembly", the entire content of which is incorporated herein by reference and relied upon.

[0002] The present disclosure generally relates to medical fluid treatment, and more particularly to dialysate treatment.

Background Art

[0003] For various reasons, a person's renal system can cease to function. Renal failure results in several physiological impairments. It is no longer possible to balance water and minerals or excrete the daily metabolic load. Toxic end products of metabolism such as urea, creatinine, and uric acid can accumulate in the patient's blood and tissues.

[0004] Reduced kidney function, particularly renal failure, is treated by dialysis. Dialysis removes excreta, toxins, and excess water from the body that a normally functioning kidney would otherwise remove. Dialysis treatment for renal function replacement is important to many people because the treatment is life-saving.

[0005] One type of renal failure treatment is hemodialysis ("HD"), which generally uses diffusion to remove waste products from the patient's blood. A diffusion gradient occurs across a semipermeable dialyzer between the blood and an electrolyte solution called the dialysate or dialysis fluid, causing diffusion.

[0006] Hemofiltration ("HF") is an alternative renal replacement therapy that relies on the convective transport of toxins from the patient's blood. HF is achieved by adding replacement or substitution fluid to the extracorporeal circuit during the treatment. The replacement fluid and fluid accumulated by the patient between treatments are ultrafiltered over the course of the HF treatment, providing a particularly beneficial convective transport mechanism for removing medium and large molecules.

[0007] Hemodiafiltration (「HDF」) is a treatment method that combines convective clearance and diffusive clearance. HDF provides diffusive clearance using dialysis fluid that flows through a dialyzer, similar to standard hemodialysis. Additionally, replacement solution is supplied directly to the extracorporeal circuit to provide convective clearance.

[0008] Most HD, HF, and HDF treatments are performed in a center. The trend towards home hemodialysis (「HHD」) exists today because HHD can be performed daily and provides therapeutic benefits over in-facility hemodialysis treatments, which are typically performed two or three times a week. Studies have shown that more frequent treatments remove more toxins and waste products and reduce interdialytic fluid overload than patients receiving less frequent, but perhaps longer, treatments. Patients receiving more frequent treatments experience fewer downcycles (fluctuations in body fluids and toxins) than in-facility patients who have accumulated two or three days' worth of toxins prior to treatment. In certain regions, the nearest dialysis center may be miles away from the patient's home, causing door-to-door treatment times to consume most of the day. Treatments at a facility close to the patient's home can also consume most of the patient's day. HHD can be performed overnight or during the day while the patient relaxes, works, or is otherwise productive.

[0009] Another type of kidney failure treatment is peritoneal dialysis (「PD」), which involves injecting a dialysis solution, also called dialysate, into the patient's peritoneal cavity through a catheter. The dialysate is in contact with the peritoneum within the patient's peritoneal cavity. Waste products, toxins, and excess water enter the dialysate from the patient's bloodstream through capillaries in the peritoneal membrane due to diffusion and osmosis (i.e., an osmotic gradient that occurs across the membrane). Osmotic agents in the PD solution provide the osmotic gradient. Used or spent dialysate is drained from the patient, removing waste products, toxins, and excess water from the patient. This cycle is repeated, for example, multiple times.

[0010] There are various types of peritoneal dialysis therapies, including continuous ambulatory peritoneal dialysis ("CAPD"), automated peritoneal dialysis ("APD"), tidal volume dialysis, and continuous flow peritoneal dialysis ("CFPD"). CAPD is a manual dialysis procedure. Here, the patient manually connects the implanted catheter to the drain to enable draining of the used or spent dialysis fluid from the peritoneal cavity. The patient then switches the fluid communication so that the patient catheter communicates with a bag of fresh dialysis fluid and fresh dialysis fluid is injected into the patient through the catheter. The patient disconnects the catheter from the fresh dialysis fluid bag, allowing the dialysis fluid to remain in the peritoneal cavity and enabling the transfer of excreta, toxins, and excess water. After the dwell period, the patient repeats the manual dialysis procedure, for example, four times a day. Manual peritoneal dialysis requires a significant amount of time and effort from the patient and leaves room for improvement.

[0011] Automated peritoneal dialysis ("APD") is similar to CAPD in that the dialysis procedure involves drain, fill, and dwell cycles. However, the APD device typically automatically executes the cycles during the patient's sleep. The APD device liberates the patient from having to manually execute the treatment cycles and from having to make replenishments during the day. The APD device is fluidly connected to the implanted catheter, a source or bag of fresh dialysis fluid, and a fluid drain. The APD device pumps fresh dialysis fluid from the dialysis fluid source through the catheter into the patient's peritoneal cavity. The APD device also enables the dialysis fluid to dwell within the chamber and the transfer of waste, toxins, and excess water. The source may contain several liters of dialysis fluid in several solution bags.

[0012] The APD device pumps the used dialysis fluid or dialysis waste fluid from the patient's peritoneal cavity through the catheter to the drain. Similar to the manual process, several drain, fill, and dwell cycles occur during dialysis. The "last fill" can occur at the end of the APD procedure. The last fill fluid can remain in the patient's peritoneal cavity until the start of the next procedure, or it can be manually emptied at some point during the day.

[0013] Known APD systems include a device or cycler that accepts and operates a pumping cassette, which has a rigid portion and a flexible portion that can deform to perform pumping and valve operations. Sealing a disposable fluid cassette with a pneumatic path through a gasket to provide operation has proven to be a potential in-field problem, which can delay treatment start times and affect the user experience. The pneumatic cassette system also generates acoustic noise, which can be a cause of customer dissatisfaction.

[0014] For each of the above reasons, an improved APD device is needed.

Summary of the Invention

Means for Solving the Problems

[0015] The present disclosure describes a rationalized automated peritoneal dialysis (「APD」) system and an associated cycler that uses a peristaltic pump and a disposable set. The disposable set weaves tubing and performs many functions discussed below. The cycler of the system in one embodiment includes a peristaltic pump actuator that can pump in two directions. Flow in either direction proceeds through a disposable cassette that is part of the entire disposable set.

[0016] The disposable cassette is mounted within the cycler housing and, in one embodiment, is mounted perpendicular to the operating surface of the housing and then enclosed between the operating surface and the hinged door of the housing. A user interface that communicates with a control unit is provided next to the door of the housing, whereby a patient or user typically interacts with one surface of the device to enter commands, receive data, and load the disposable cassette.

[0017] The system in one embodiment also includes a bag shelf enclosure that serves multiple purposes. The bag shelf enclosure is sized such that a cycler can be stored inside the enclosure when not in use. The bag shelf enclosure is also sized such that the bag shelf enclosure can be set on top of the cycler when the cycler is in use. The bag shelf holds a plurality of containers or bags, such as a plurality of supply containers and one or more drain containers. In one example, a plurality of supply containers are placed inside the bag shelf enclosure during treatment, and the drain container and the last fill container are placed outside and on top of the enclosure. The bag shelf enclosure may include color-coded markers provided at positions for loading containers or bags having lines that extend into the cycler through an aperture, and the aperture has similarly color-coded markers. The matching color-coded markers facilitate identification by the patient or caregiver of which bag and line belong to which position on the bag shelf enclosure.

[0018] It is contemplated to use a supply container or bag later as a drain container or bag to reduce the overall disposable cost. For example, assume a patient is full of effluent at the start of treatment. The effluent is first drained from the patient and delivered to an empty drain container. Then, the first patient fill is delivered from the first supply container to the patient and, after a specified dwell period, is delivered to the same or a different drain container depending on the size of the drain container. The drain container is used to receive effluent until the first supply container is empty, after which the first supply container receives effluent after a dwell period using PD fluid supplied from the second supply container. The first supply container is used to receive effluent, perhaps over a plurality of patient fills, dwells, and discharges, until the second supply container is empty. At that point, the patient may receive the last fill of a different prescription of peritoneal dialysis fluid, which remains inside the patient until the next night's treatment, or perhaps until the day exchange.

[0019] At the end of the treatment, the plurality of containers or bags are filled with effluent. To prevent the patient or caregiver from having to transport the drain bag to a house drain, such as a toilet, sink or bathtub, the cycler control unit is programmed to remove the patient line from the patient transfer set and prompt the user to carry the distal end of the patient line to the house drain. It should be understood that "house drain" as used herein means any type of drain provided in any type of building or dwelling place, such as a house, apartment, work building, hospital, clinic, public or private facility. Optionally, a reusable extension line may be connected to the distal end of the patient line to reach the house drain. The patient or caregiver then presses the drain button on the user interface, at which time the cycler withdraws the used dialysate or effluent from each of the drain containers (one or more of which may be a previous supply container) and operates the peristaltic pump actuator in a direction to pump the used dialysate through the patient line (and the extension line if necessary) to the house drain. The cycler detects when each drain container is empty (e.g., via a weigh scale and / or pressure sensor described in detail below) and automatically switches the valve actuator, such as a pinch valve actuator, in sequence between the drain containers until each drain container is empty. The above sequence is repeated for any remaining fresh dialysate in the main supply container or the last fill container. It should be understood that the plurality of drain containers (one or more of which may be a previous supply container) can be drained in parallel or simultaneously, for example to save time. In this way, when the patient disconnects the patient line and presses the drain button, the patient is free to start the day.

[0020] As described above, in one embodiment, the cycler uses peristaltic pumping. The peristaltic pump actuator, under the control of the control unit, is disposed on the working surface of the cycler. The disposable cassette includes a peristaltic pump tube that the user guides over the peristaltic pump actuator when loading the cassette. During operation, the peristaltic pump actuator compresses the peristaltic pump tube against the track at multiple points. The proximity of the track to the peristaltic pump actuator makes it difficult to load the tube. Thus, the cycler includes a movable track that translates in parallel via a link so as not to interfere with the peristaltic pump actuator when the patient or caregiver opens the cycler door to load the cassette. After the cassette is loaded, closing the cycler door translates the movable track via a linkage mechanism to an operable position directly adjacent to the peristaltic pump tube. In an alternative embodiment, a motor and lead screw assembly, or a linear actuator (e.g., a linear stepper motor) is provided to automatically translate the track in parallel so as not to interfere with the peristaltic pump actuator when the patient or caregiver opens the cycler door to load the cassette and to automatically translate the track to an operable position when the door is closed. In a further alternative embodiment, a motor and lead screw assembly, or a linear actuator (e.g., a linear stepper motor) is provided, but the patient or caregiver instead presses one or more buttons on the user interface to translate the track in parallel so as not to interfere or to an operable position.

[0021] In an embodiment, the track is attached to a block or member that is translatable across the working surface towards and away from the peristaltic pump actuator. In addition to the translational movement of the member (and the track), the movable track can also rotate about a pivot axis provided at one end of the track, and the pivot axis is attached to the translatable member. The other end of the track is spring-loaded via a spring, such as a compression spring, confined between the track end and the member. The spring pushes the track into a desired operating position around the peristaltic pump tube about the pivot axis when the member is translated towards the peristaltic pump actuator. The pivoting track can absorb or tolerate variations due to tube tolerances and can also provide a damping effect that helps reduce noise.

[0022] As described above, in one embodiment, the cycler uses a pinch valve actuator, and the disposable cassette provides a valve seat that receives the pinch valve actuator to occlude or close the fluid path provided by the disposable cassette. Here, the cassette is sealed and covered with a flexible sheet, such as flexible plastic, into which the pinch valve actuator is pushed into each valve seat to close each fluid path. The pinch valve actuator retracts to open their respective fluid paths.

[0023] The pinch valves are each driven by a linear actuator, which can be any suitable type of linear actuator such as a linear stepping motor that provides the required amount of movement (e.g., up to 10 mm maximum) and the required amount of pressure cassette seat closing force (e.g., 30 to 60 Newtons ("N") or less). The linear actuator can drive the valve plunger back and forth to press the cassette seat against the cassette valve seat and to allow the seat to be removed from the cassette valve seat. The valve plunger in one embodiment includes a proximal end effector that couples to the linear actuator and a distal end effector that slidably couples to the proximal end effector. A spring, such as a waveform or compression spring, can be provided to the plunger and arranged to bias the distal end effector outwardly relative to the proximal end effector. The variable distance provided by the spring allows the pinch valve to first contact the cassette seat with a smaller closing force that steadily increases as the spring is compressed. In an embodiment, a flexible membrane, such as a silicone membrane, is secured to the working surface to cover the end of the distal end effector such that the flexible membrane contacts the cassette seat. When the spring is fully compressed, the cassette seat experiences the full force of the linear actuator and the spring. Thus, the spring provides a force buffer that helps protect the flexible membrane over multiple treatments and the cassette seat over the course of a single treatment. The spring can help with the tolerances of the disposable cassette and variations due to cassette loading and can further allow for a smaller or less expensive linear actuator.

[0024] As described above, the disposable cassette provides a plurality of valve seats that can include a patient line valve seat, first and second supply line valve seats, a final fill line valve seat, and a drain line valve seat. In one embodiment, the patient line valve seat is fluidly separated from the first peristaltic tube port by an in-line fluid heating path, such as a serpentine path. When the disposable cassette is mounted for operation, the in-line fluid heating path is adjacent to a heater, such as a resistive plate heater.

[0025] In one embodiment, the first and second supply line valve seats, the last fill line valve seat, and the drain line valve seat are each disposed within a common well that is in fluid communication with a second peristaltic tube port. In this way, fresh dialysate can be pumped from either the supply container for the first and second supply line valve seats or the last fill line valve seat, in a first direction, through the common well and in-line fluid heating path where the fresh dialysate is heated, and then to the patient from the patient line valve seat. Used dialysate or effluent can be pumped from the patient, in a second direction, through the patient line valve seat and in-line fluid heating path where the used dialysate is not heated, to the common well, and then to the drain container from the drain line valve seat.

[0026] Any of the valve seats described herein may include a tapered seal surface surrounded by a plurality of displacement ribs, each displacement rib extending from a rigid wall of the disposable cassette, with at least some of the displacement ribs being spaced to prevent or relieve unwanted occlusion of the tapered seal surface by the flexible sheet and to allow fresh or used dialysis flow therethrough. The displacement ribs may be completely separated from each other or may extend from a common cylindrical base. The displacement ribs may be separated from the tapered seal surface or may extend from the outer edge of the tapered seal surface. The displacement ribs prevent entry of the flexible sheet into the tapered seal surface. The displacement ribs may guide respective pinch valve plungers toward the center of the valve seat while providing a certain amount of elasticity or play between the pinch valve plunger and the valve seat. In an embodiment, the tapered seal surface tapers to form a funnel shape leading to an opening that allows fresh or used dialysate to flow into or out of the valve seat. In an embodiment, the opening extends through a port disposed on the other side of the rigid body of the disposable cassette, the port sealably receiving (attaching to) a tube or line such as a patient line, supply line, or drain line. The tapered seal surface may also include or define one or more circular seal rings that push the flexible sheet inward when the flexible sheet is closed by the pinch valve.

[0027] In an embodiment, the first or patient pressure sensing pod is disposed within a disposable cassette directly adjacent to a patient line valve seat. The patient pressure sensing pod when the disposable cassette is loaded is positioned adjacent to a first or patient pressure sensor that outputs to a cycler control unit. The patient pressure sensor output can be used to control the positive and negative pumping pressures received by the patient within safe pressure limits. The second or pumping pressure sensing pod is disposed within the disposable cassette between a common well and a second peristaltic tube port. The pumping pressure sensing pod when the disposable cassette is loaded is positioned adjacent to a second or pumping pressure sensor that outputs to a cycler control unit. The pumping pressure sensor output can be used to detect occlusions in supply and drain lines and / or to supply an empty state.

[0028] The disposable cassette may also include one or more regions adjacent to a thermocouple or other temperature sensor that outputs to a control unit when loaded for operation. The temperature sensing region can be disposed, for example, at the end of an in-line fluid heating path directly adjacent to the patient pressure sensing pod, such that the outlet temperature of fresh dialysate to the patient is monitored and controlled by the control unit via a proportional, integral, derivative ("PID") routine, for example, using feedback from the temperature sensor, to a desired temperature such as body temperature or 37°C. A second temperature sensor can be disposed to detect the temperature at the inlet of the in-line fluid heating path as needed, which can similarly provide useful information for the PID routine.

[0029] When a disposable cassette is loaded for operation, a cassette sheet, which can be polyvinyl chloride ("PVC"), is contacted by a pressure sensor and placed under tension to generate a baseline force measured by the pressure sensor. It is conceivable to mount the pressure sensor on the working surface of the cycler. Fresh or used dialysate pressure further displaces (or attempts to displace) the cassette sheet, thereby increasing or decreasing the fluid force acting on the pressure sensor relative to the baseline force. The difference in force caused by positive or negative fluid pressure is related to the actual fluid pressure value by a control unit, and they can be used for pressure control, displayed by a user interface, and / or stored for delivery to a remote computer for evaluation.

[0030] Pre-tensioning of the cassette sheet by the pressure sensor results in a pressure sensing regime with high sensitivity and resolution, but it can be prone to being temperature-sensitive. Therefore, it is conceivable to compensate for temperature. Here, the voltage output (or current output) from the pressure sensor is modified by adding a component that is a function of the measured temperature multiplied by an empirically determined temperature scaling factor (e.g., using the thermocouple described above) to form a compensated voltage output, and the compensated voltage output is converted or related to the compensated positive or negative pressure.

[0031] As described above, pre-tensioning of the cassette sheet by the pressure sensor results in a pressure sensing regime with high sensitivity and resolution, but mechanical creep sensitivity can also easily occur. To counter creep sensitivity, in one embodiment, the control unit is programmed to pre-condition the cassette sheet, for example during setup, prior to treatment, whereby much of the variation in the pressure signal due to creep is eliminated before the pressure measurement becomes problematic. To do so, after the disposable cassette is primed, the control unit closes all pinch valves and then operates the peristaltic pump actuator to pressurize the interior of the cassette containing the pressure pod to stretch the cassette sheet. The control unit may be programmed to cyclically oscillate the cassette fluid pressure up and down a plurality of times over a specified period of time to the pump actuator, and the upper limit pressure may be, for example, from 100% to 150% of the maximum operating pressure set for the treatment. Pre-conditioning of the cassette sheet helps to make the uncompensated pressure readings more accurate, while temperature compensation helps to make the final pressure readings more accurate.

[0032] The systems and cyclers of the present disclosure, in one embodiment, use a scale having a plurality of load cells to monitor the amount of fresh dialysate delivered to the patient and the amount of used dialysate removed from the patient, enabling the control unit to calculate the amount of ultrafiltration ("UF") removed from the patient therefrom. The scale and load cells are advantageous for several reasons. First, the scale is relatively accurate compared to other volume measurement techniques. Second, the pump actuator can be a relatively simple peristaltic pump actuator, and the disposable portion of the pump can be a simple peristaltic pump tube, so the scale reduces pump costs.

[0033] One drawback of the use of load cells is calibration. Load cells can be inaccurately read over time and thus need to be recalibrated. The cycler and related systems of the present invention provide a weighing scale having a plurality of load cells and an on-board structure and methodology for calibrating the weighing scale. In one embodiment, the weighing scale includes a bag shelf enclosure and a weight plate disposed on top of the cycler that supports the weight of the solution and drain container, and each of the associated fresh and used dialysate. The weight plate and each weighing article on the weight plate are supported by a plurality, e.g., four, load cells that collectively measure the total mass (bag shelf enclosure, containers, and fluids) disposed on the weight plate. The on-board calibration structure in one embodiment includes a fifth load cell and a linear actuator (which can be of the same type used in pinch valves) disposed between the fifth load cell and the weight plate.

[0034] The linear actuator includes an actuating output shaft fixed to the weight plate such that the linear actuator can apply a pulling or downward force to the weight plate. In one implementation, the pulling force is applied to the center of mass of the lower surface of the weight plate. The additional calibration load cell measures the total applied force while the four operational load cells each measure a portion or one quarter of the total force. If each of the operational load cells is operating properly, the sum of their outputs must equal the total force measured by the calibration load cell. In one example, assume a pulling force of 1000 Newtons ("N") is applied by the linear actuator. The calibration load cell then outputs 1000 N and the equidistant operational load cells 102a - 102d each read 250 N and must sum to 1000 N in combination.

[0035] Since the calibration load cell is used rarely, a calibration algorithm is applied assuming that the output of the calibration load cell is more accurate than the collective output of the operational load cells used throughout each procedure. Thus, during calibration, if there is a discrepancy between what the calibration load cell reads and the collective output of the operational load cells, the control unit using the calibration algorithm scales or offsets the collective output of the operational load cells to match the collective output of the calibration load cell. In the above example, assume that the operational load cells actually collectively read 995 N instead of 1000 N. Thus, the reading of the operational load cells is 0.5% lower. Thereby, the control unit is configured to correct the collective output of the operational load cells by a calibration factor of 1000 / 995 or 1.005 during the procedure.

[0036] Since the calibration load cell is used rarely, the calibration algorithm assumes that its output is more accurate than the collective output of the operational load cells used throughout each procedure. Thus, during calibration, if there is a discrepancy between what the calibration load cell reads and the collective output of the operational load cells, the control unit using the calibration algorithm scales or offsets the collective output of the operational load cells to match the collective output of the calibration load cell. In the above example, assume that the operational load cells actually collectively read 605 N instead of 600 N. Thus, the operational load cells detect only 395 N out of the 400 N applied. Thus, the reading of the operational load cells is 1.3% lower. Thereby, the control unit of the cycler is configured to correct the collective output of the operational sensors by a calibration factor of 400 / 395 or 1.01 during the procedure.

[0037] The load cell calibration routine or algorithm is executed at some desired criterion, for example, before the start of each procedure. Since many of the weight values monitored and collected during the procedure are weight differences, it should also be understood that the error in the collective output of the operating load cells tends to cancel out, assuming that the error does not change over the course of the procedure. For example, the mass associated with a 2 liter patient fill volume is monitored and controlled by the collective output of the operating load cells that record the decrease in mass over the course of patient filling. The volume and mass associated with the patient drain can be preset in the control unit and, for example, the fill volume can be multiplied by a factor such as 1.3 to account for the patient UF removed within the drain volume. The volume and mass associated with the patient drain can alternatively be left open-ended and instead controlled by detecting the characteristic increase in negative pressure by the pumping pressure sensing pod and associated pressure sensor, which indicates that the patient is essentially completely drained and that further drain can be uncomfortable for the patient. In either case, the operating load cells detect an increase in weight over the course of patient drain that should tend to cancel out the error of the operating load cells.

[0038] In a first aspect, which is in no way limiting of the disclosure in light of the disclosure described herein, but which may be combined with any other aspect or portion thereof, a peritoneal dialysis system includes a cycler including a pump actuator; a disposable set including a pumping section operable with the pump actuator, a patient line disposed in fluid communication with the pumping section, and a drain container disposed in fluid communication with the pumping section; and a control unit configured to operate the pumping section to cause the pump actuator to (i) perform a peritoneal dialysis procedure in which fresh dialysate is pumped through the patient line to the patient and used dialysate is pumped from the patient to the drain container, and (ii) at the end of the procedure, pump the used dialysate from the drain container through the patient line to the house drain.

[0039] In a second aspect of the disclosure that can be combined with any other aspect or portion thereof, the pump actuator is a peristaltic pump actuator, and the disposable set's pumping section includes a peristaltic pump tube.

[0040] In a third aspect of the disclosure that can be combined with any other aspect or portion thereof, the peritoneal dialysis system includes an extension line configured to be connected to the patient line to reach the home drain as needed.

[0041] In a fourth aspect of the disclosure that can be combined with any other aspect or portion thereof, the extension line is reusable.

[0042] In a fifth aspect of the disclosure that can be combined with any other aspect or portion thereof, the peritoneal dialysis system includes a user interface that communicates with a control unit, and the user interface is configured to prompt the patient to disconnect the patient line and move the patient line towards the home drain at the end of the procedure.

[0043] In a sixth aspect of the disclosure that can be combined with any other aspect or portion thereof, the peritoneal dialysis system includes a user interface that communicates with a control unit, and the user interface is configured to provide or enable a drain button at the end of the procedure to initiate pumping of used dialysate from the drain container to the home drain via the patient line.

[0044] In a seventh aspect of the disclosure that can be combined with any other aspect or portion thereof, the user interface is further configured to require confirmation that the drain line is in fluid communication with the home drain before providing or enabling the drain button.

[0045] In an eighth aspect of the disclosure that can be combined with any other aspect or a part thereof, the cycler includes a patient valve actuator that operates with a patient valve seat provided by a disposable set, and a drain valve actuator that operates with a drain valve seat provided by the disposable set, and the control unit is configured to enable flow through the patient valve seat and the drain valve seat to the patient valve actuator and the drain valve actuator, and to pump used dialysate from the drain container through the patient line to the house drain.

[0046] In a ninth aspect of the disclosure that can be combined with any other aspect or a part thereof, at least one of the patient valve actuator or the drain valve actuator is a pinch valve actuator.

[0047] In a tenth aspect of the disclosure that can be combined with any other aspect or a part thereof, the peritoneal dialysis system includes a supply container arranged to be in fluid communication with a pumping section of a disposable set, and the supply container is used during peritoneal dialysis procedures to pump fresh dialysate to the patient through the patient line.

[0048] In an eleventh aspect of the disclosure that can be combined with any other aspect or a part thereof, the supply container is later used during peritoneal dialysis procedures to receive used dialysate from the patient.

[0049] In a twelfth aspect of the disclosure that can be combined with any other aspect or a part thereof, the cycler includes a sensor that communicates operably with the control unit, and the control unit uses the output from the sensor to determine whether one of the drain container or the supply container that is later used as the drain container is empty or substantially empty after pumping used dialysate to the house drain, and then is configured to switch to the other of the drain container or the supply container that is later used as the drain container for pumping used dialysate to the house drain.

[0050] In a 13th aspect of the disclosure that can be combined with any other aspect or a part thereof, the sensor is a weight sensor or a pressure sensor.

[0051] In a 14th aspect of the disclosure that can be combined with any other aspect or a part thereof, the control unit is further configured to cause the pump actuator to operate the pumping section at the end of the treatment to pump the remaining fresh dialysis fluid from the supply container through the patient line to the house drain.

[0052] In a 15th aspect of the disclosure that can be combined with any other aspect or a part thereof, the drain container is a first drain container and includes a second drain container arranged to be in fluid communication with the pumping section of the disposable set, the cycler includes a sensor operably communicating with the control unit, and the control unit is configured to use the output from the sensor to determine whether the first drain container is empty or substantially empty after pumping the used dialysis fluid to the house drain, and then switch to the second drain container to pump the used dialysis fluid to the house drain.

[0053] In a 16th aspect of the disclosure that can be combined with any other aspect or a part thereof, the sensor of the 15th aspect is a weight sensor or a pressure sensor.

[0054] In a 17th aspect of the disclosure that can be combined with any other aspect or a part thereof, the drain container is a first drain container and includes a second drain container arranged to be in fluid communication with the pumping section of the disposable set, and the control unit is configured to drain the first and second drain containers simultaneously.

[0055] In an eighteenth aspect of the disclosure that can be combined with any other aspect or a part thereof, a peritoneal dialysis system includes a cycler including a pump actuator; a disposable set including a pumping unit operable with the pump actuator, a patient line disposed to be in fluid communication with the pumping unit, and a drain line disposed to be in fluid communication with the pumping unit; and a control unit configured to cause the pump actuator to (i) perform a peritoneal dialysis procedure in which fresh dialysis fluid is pumped through the patient line to a patient and used dialysis fluid is pumped from the patient through the drain line, and (ii) at the end of the procedure, cause the pumping unit to pump the used dialysis fluid through the drain line and the patient line to a house drain.

[0056] In a nineteenth aspect of the disclosure that can be combined with any other aspect or a part thereof, the drain line is in fluid communication with a drain container, and the drain container is initially provided as a drain container or supply container filled with fresh dialysis fluid.

[0057] In a twentieth aspect of the disclosure that can be combined with any other aspect or a part thereof, the patient line and the drain line are separated by a disposable cassette of the disposable set, and at the end of the procedure, the used dialysis fluid is pumped through the drain line, through the disposable cassette, through the patient line, and to the house drain.

[0058] In a twenty - first aspect of the disclosure that can be combined with any other aspect or a part thereof, the disposable cassette includes a pressure sensing pod arranged to enable detection of a pressure change indicating that a drain container in fluid communication with the drain line is empty, and then the control unit switches to drain the used dialysis fluid from a different source to the house drain at the end of the procedure.

[0059] In a 22nd aspect that can be combined with any other aspect or part thereof of the present disclosure, the cycler includes a weighing scale, a drain container in fluid communication with a drain line is arranged to be weighed by the weighing scale, and an output from the weighing scale indicating that the drain container is empty is used by a control unit to switch to draining used dialysate from a different source to a house drain at the end of a treatment.

[0060] In a 23rd aspect of the present disclosure that can be combined with any other aspect or part thereof, a peritoneal dialysis system includes a cycler including a pump actuator; a disposable set including a pumping section operable with the pump actuator, a patient line arranged to be in fluid communication with the pumping section, and a drain container arranged to be in fluid communication with the pumping section; and a control unit configured to cause the pumping section to (i) perform a peritoneal dialysis treatment in which fresh dialysate is pumped through the patient line to a patient and used dialysate is pumped from the patient to the drain container, and (ii) at the end of the treatment, pump the used dialysate from the drain container through the patient line to a desired destination.

[0061] In a 24th aspect of the present disclosure that can be combined with any other aspect or part thereof, the desired destination includes a house drain or another container arranged to be in fluid communication with the pumping section.

[0062] In a 25th aspect of the present disclosure that can be combined with any other aspect or part thereof, pumping used dialysate from the drain container through the patient line during (ii) includes operating the pumping section in a first direction to at least partially fill the patient line with the used dialysate and then operating the pumping section in a second direction to remove the used dialysis from the patient line to the desired destination.

[0063] In a 26th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the disposable medical fluid cassette includes a pumping section, a patient line valve seat arranged to be in fluid communication with the pumping section, a rigid body that defines a common well, the common well being in fluid communication with the pumping section, at least one supply line valve seat arranged in the common well, and a drain line valve seat arranged in the common well.

[0064] In a 27th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the patient line valve seat is provided by the rigid body.

[0065] In a 28th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the pumping section includes a peristaltic pump tube attached to the rigid body.

[0066] In a 29th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the pumping section includes a pump chamber defined by the rigid body.

[0067] In a 30th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the rigid body defines an in-line fluid heating path arranged between the patient line valve seat and the pumping section.

[0068] In a 31st aspect of the present disclosure that can be combined with any other aspect or a part thereof, the disposable medical fluid cassette includes a temperature sensing region arranged between the patient line valve seat and the in-line fluid heating path.

[0069] In a 32nd aspect of the present disclosure that can be combined with any other aspect or a part thereof, the in-line fluid heating path is configured to remove air passing through the patient line valve seat as fresh dialysate flows upward during priming.

[0070] In a 33rd aspect of the disclosure that can be combined with any other aspect or a part thereof, the disposable medical fluid cassette includes at least one of a pumping pressure sensing pod disposed between a drain line valve seat and a first end of the in-line fluid heating path, or a patient pressure sensing pod disposed between a patient line valve seat and a second end of the in-line fluid heating path.

[0071] In a 34th aspect of the disclosure that can be combined with any other aspect or a part thereof, the disposable medical fluid cassette includes at least one of a patient line in fluid communication with a patient line valve seat, at least one supply line in fluid communication with at least one supply line valve seat, or a drain line in fluid communication with a drain line valve seat.

[0072] In a 35th aspect of the disclosure that can be combined with any other aspect or a part thereof, the disposable medical fluid cassette includes at least one of a pumping pressure sensing pod disposed adjacent to a patient line valve seat, or a pumping pressure sensing pod disposed adjacent to a common well.

[0073] In a 36th aspect of the disclosure that can be combined with any other aspect or a part thereof, the disposable medical fluid cassette includes a flexible sheet sealed to a rigid body, and the flexible sheet is bent to open and close at least one supply line valve seat and a drain line valve seat.

[0074] In a 37th aspect of the disclosure that can be combined with any other aspect or a part thereof, the rigid body includes a rigid wall defining a common well, and the flexible sheet is sealed to the rigid wall so as to surround the common well.

[0075] In a 38th aspect of the disclosure that can be combined with any other aspect or a part thereof, at least one of a patient line valve seat, at least one supply line valve seat, or a drain line valve seat includes a tapered sealing surface surrounded by a plurality of displacement ribs, and at least some of the displacement ribs are spaced apart to ease the entry of a flexible sheet into the tapered sealing surface.

[0076] In a 39th aspect of the disclosure that can be combined with any other aspect or a part thereof, the common well includes an inclined surface configured to direct air within the common well toward the drain line valve seat.

[0077] In a 40th aspect of the disclosure that can be combined with any other aspect or a part thereof, the drain line valve seat is disposed relative to at least one supply line valve seat within the common well, such that the drain line valve seat is positioned higher than the at least one supply line valve seat to direct air toward the drain line valve seat when a disposable medical fluid cassette is loaded for operation.

[0078] In a 41st aspect of the disclosure that can be combined with any other aspect or a part thereof, a peritoneal dialysis system includes a cycler including a pump actuator, a patient line valve actuator, at least one supply line valve actuator, and a drain line valve actuator; a pumping section configured to operate with the pump actuator; a patient line valve seat configured to operate with the patient line valve actuator; a rigid body defining a common well; at least one supply line valve seat disposed within the common well and configured to operate with the at least one supply line valve actuator; and a disposable medical fluid cassette including a drain line valve seat disposed within the common well and configured to operate with the drain line valve actuator.

[0079] In a 42nd aspect of the present disclosure that can be combined with any other aspect or a part thereof, the cycler is configured to perform a patient drain in which used dialysate enters a common well, followed by a patient fill in which fresh dialysate enters the common well.

[0080] In a 43rd aspect of the present disclosure that can be combined with any other aspect or a part thereof, during patient drain, a drain line valve actuator is actuated so that used dialysate can exit the common well through a drain line valve seat, and during patient fill, one of at least one supply line valve actuators is actuated so that fresh dialysate can enter the common well through one of at least one supply line valve seats.

[0081] In a 44th aspect of the present disclosure that can be combined with any other aspect or a part thereof, during patient drain and patient fill, a patient line valve actuator is actuated so that used dialysate and fresh dialysate can flow through a patient line valve seat, respectively.

[0082] In a 45th aspect of the present disclosure that can be combined with any other aspect or a part thereof, a valve seat for a disposable medical fluid cassette includes a rigid wall and a tapered seal surface extending from the rigid wall, the tapered seal surface surrounding an opening formed in the rigid wall, and a plurality of displacement ribs extending from the rigid wall or from the outer edge of the tapered seal surface so as to surround the tapered seal surface, the displacement ribs being spaced apart to relieve unwanted blockage of the tapered seal surface.

[0083] In a 46th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the displacement ribs are separated from each other or extend from a common cylindrical base.

[0084] In a 47th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the tapered seal surface is cylindrical, and the displacement ribs collectively form a cylindrical shape surrounding the tapered seal surface.

[0085] In a 48th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the tapered seal surface forms a funnel shape leading to an opening.

[0086] In a 49th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the opening extends through a port disposed on the opposite side of the rigid wall from the tapered seal surface and the displacement ribs.

[0087] In a 50th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the tapered seal surface includes at least one circular seal ring for pressing into a mating seal member.

[0088] In a 51st aspect of the present disclosure that can be combined with any other aspect or a part thereof, the pinch valve includes a linear actuator, a proximal end effector coupled to the linear actuator, a distal end effector slidably engaged with the proximal end effector, and a spring positioned and arranged to bias the distal end effector outward relative to the proximal end effector.

[0089] In a 52nd aspect of the present disclosure that can be combined with any other aspect or a part thereof, the linear actuator includes a linear stepping motor.

[0090] In a 53rd aspect of the present disclosure that can be combined with any other aspect or a part thereof, the proximal end effector and the distal end effector form a valve plunger.

[0091] In a 54th aspect of the disclosure that can be combined with any other aspect or a part thereof, the proximal end effector includes a larger diameter portion and a smaller diameter portion, and the distal end effector includes a cylindrical opening that slidably receives the smaller diameter portion of the proximal end effector.

[0092] In a 55th aspect of the disclosure that can be combined with any other aspect or a part thereof, the spring is disposed between a step portion that transitions between the larger diameter portion and the smaller diameter portion and the distal end effector.

[0093] In a 56th aspect of the disclosure that can be combined with any other aspect or a part thereof, the spring is constrained by the smaller diameter portion of the proximal end effector.

[0094] In a 57th aspect of the disclosure that can be combined with any other aspect or a part thereof, the outer diameter of the distal end effector is at least substantially equal to the outer diameter of the larger diameter portion of the proximal end effector.

[0095] In a 58th aspect of the disclosure that can be combined with any other aspect or a part thereof, the spring is a wave spring or a compression spring.

[0096] In a 59th aspect of the disclosure that can be combined with any other aspect or a part thereof, one of the proximal end effector or the distal end effector defines at least one groove, and the other of the proximal end effector or the distal end effector includes at least one spring arm that mechanically fits into the at least one groove.

[0097] In a 60th aspect of the disclosure that can be combined with any other aspect or a part thereof, the at least one groove is sized to provide a movement length of the distal end effector relative to the proximal end effector that is greater than or equal to the uncompressed length of the spring.

[0098] In a 61st aspect of the present disclosure that can be combined with any other aspect or a part thereof, the dialysis device includes an operating surface loaded with a fluid transport member for performing a dialysis treatment; a hole formed in the operating surface; a linear actuator; a proximal end effector coupled to the linear actuator; a distal end effector slidably engaged with the proximal end effector; and a pinch valve including a spring positioned and arranged to bias the distal end effector outward relative to the proximal end effector, and the pinch valve is mounted in the device such that the distal end effector extends through the hole to block a part of the fluid transport member.

[0099] In a 62nd aspect of the present disclosure that can be combined with any other aspect or a part thereof, the hole is covered by a flexible membrane, and the distal end effector bends the flexible membrane to block a part of the fluid transport member.

[0100] In a 63rd aspect of the present disclosure that can be combined with any other aspect or a part thereof, the pinch valve is mounted in the device such that the spring is compressed before a part of the fluid transport member experiences a full closing force applied by the linear actuator.

[0101] In a 64th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the hole is a first hole, the pinch valve is a first pinch valve, the operating surface defines a second hole adjacent to the first hole, and includes a second pinch valve mounted in the device, and the distal end effector of the second pinch valve extends through the second hole to block a second part of the fluid transport member.

[0102] In a 65th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the dialysis device includes a control unit programmed to sequence the first and second pinch valves according to a pre-programmed sequence.

[0103] In a 66th aspect of the present disclosure that can be combined with any other aspect or a part thereof, a dialysis device operable with a disposable set having a peristaltic pump tube includes an operating surface for receiving the disposable set, a peristaltic pump actuator extending from the operating surface, the peristaltic pump actuator being operable with the peristaltic pump tube, a member movable in parallel along the operating surface, a track pivotally connected to the member via a pivot axis at a first end, and a spring biasing the second end of the track outwardly from the member about the pivot axis.

[0104] In a 67th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the dialysis device includes a stopper arranged to limit the distance by which the spring can push the second end of the track outwardly from the member.

[0105] In a 68th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the spring is arranged around the stopper.

[0106] In a 69th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the stopper is connected to the member and moves with the member.

[0107] In a 70th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the stopper extends through an aperture or opening formed in the second end of the member and includes a head larger than at least one dimension of the aperture or opening, and the spring is biased to press the second end of the member against the head.

[0108] In a 71st aspect of the present disclosure that can be combined with any other aspect or a part thereof, the spring is a compression or tension spring.

[0109] In a 72nd aspect of the present disclosure that can be combined with any other aspect or a part thereof, the member includes a base defining an arc having a radius that at least substantially matches the radius of the track.

[0110] In a 73rd aspect of the present disclosure that can be combined with any other aspect or a part thereof, the dialysis device includes a stopper arranged to stop the turning of the orbit caused by the spring when the radius of the orbit reaches at least substantially the radius of the arc.

[0111] In a 74th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the working surface defines a linear rail, the member translates parallel along the linear rail, and the lower surface of the member includes a rail receiver sized to operate with the linear rail.

[0112] In a 75th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the linear rail and the rail receiver are formed such that the linear rail slidably holds the member with respect to the working surface.

[0113] In a 76th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the member defines at least one slot to enable the member to be slidably attached to the working surface.

[0114] In a 77th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the dialysis device includes a door configured to open and close with respect to the working surface, and further includes a link mechanism positioned and arranged such that when the door is open, the orbit is translated parallel away from the peristaltic pump actuator, and when the door is closed, the orbit is translated parallel to an operable position with respect to the peristaltic pump actuator.

[0115] In a 78th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the dialysis device includes a door configured to open and close with respect to the working surface, and further includes an electric assembly configured to translate the orbit away from the peristaltic pump actuator and translate the orbit to an operable position with respect to the peristaltic pump actuator at different times.

[0116] In a 79th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the electric mechanism includes a motor operable by a lead screw or a linear actuator.

[0117] In an 80th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the electric mechanism is configured to (i) automatically translate away from the peristaltic pump actuator along the track when the door is opened and automatically translate to a position operable with respect to the peristaltic pump actuator along the track when the door is closed, or (ii) translate away from the peristaltic pump actuator along the track in response to at least one user interface input and / or translate to a position operable with respect to the peristaltic pump actuator along the track at different times.

[0118] In an 81st aspect of the present disclosure that can be combined with any other aspect or a part thereof, a dialysis device operable with a disposable set having a peristaltic pump tube includes an operating surface for receiving the disposable set, a peristaltic pump actuator extending from the operating surface, the peristaltic pump actuator being operable with the peristaltic pump tube, a track movable parallel to the operating surface, a door openable and closable with respect to the operating surface, and a link mechanism or an electric mechanism configured to (i) translate the peristaltic pump tube away from the peristaltic pump actuator to a position against the peristaltic pump actuator and (ii) translate the peristaltic pump tube to a position operable with respect to the peristaltic pump actuator.

[0119] In an 82nd aspect of the present disclosure that can be combined with any other aspect or a part thereof, a link mechanism is provided, and the link mechanism is configured and arranged such that (i) is executed when the door is opened and (ii) is executed when the door is closed.

[0120] In an 83rd aspect of the present disclosure that can be combined with another aspect or a part thereof, an electric mechanism is provided, and the electric mechanism is configured and arranged such that (i) is automatically executed when the door is opened and (ii) is automatically executed when the door is closed.

[0121] In an 84th aspect of the present disclosure that can be combined with any other aspect or a part thereof, an electric mechanism is provided, and the electric mechanism is such that at least one of (i) or (ii) is executed in response to a user interface input.

[0122] In an 85th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the electric mechanism includes a motor operable by a lead screw or a linear actuator.

[0123] In an 86th aspect of the present disclosure that can be combined with any other aspect or a part thereof, a medical fluid system includes a medical fluid pump actuator, a medical fluid delivery set having a flexible sheet, a temperature sensor positioned and arranged to detect the temperature of the medical fluid flowing through the medical fluid delivery set, a pressure sensor positioned and arranged to contact the flexible sheet when the medical fluid delivery set is loaded for operation by the medical fluid pump actuator, and a control unit configured to (i) precondition the flexible sheet for operation with the pressure sensor by causing the medical fluid pump actuator to apply pressure to the flexible sheet and (ii) use the output from the temperature sensor in a compensation algorithm that corrects the output from the pressure sensor.

[0124] In an 87th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the medical fluid pump actuator is a peristaltic pump actuator.

[0125] In an 88th aspect of the disclosure that can be combined with any other aspect or a part thereof, when the medical fluid delivery set is loaded for operation by a medical fluid pump actuator, the pressure sensor is arranged such that the flexible sheet is placed under tension through contact with the pressure sensor.

[0126] In an 89th aspect of the disclosure that can be combined with any other aspect or a part thereof, the pressure sensor is operable with the pressure pod portion of the flexible sheet.

[0127] In a 90th aspect of the disclosure that can be combined with any other aspect or a part thereof, throughout (i), the pressure applied is a fluid pressure.

[0128] In a 91st aspect of the disclosure that can be combined with any other aspect or a part thereof, throughout (i), the pressure applied is a periodic up-and-down pressure.

[0129] In a 92nd aspect of the disclosure that can be combined with any other aspect or a part thereof, throughout (i), the pressure applied is from 100% to 150% of the maximum operating pressure supplied during the treatment.

[0130] In a 93rd aspect of the disclosure that can be combined with any other aspect or a part thereof, the medical fluid system includes a plurality of valves operable by the medical fluid delivery set, and the control unit causes the plurality of valves to be closed throughout (i).

[0131] In a 94th aspect of the disclosure that can be combined with any other aspect or a part thereof, the algorithm is V T = V0 + gT, where V0 is the output from the pressure sensor, V T is the corrected pressure output, g is the temperature scaling factor, and T is the detected temperature.

[0132] In a 95th aspect of the present disclosure that can be combined with other aspects or portions thereof, the control unit is configured to update a temperature compensation algorithm (i) each time the output from the pressure sensor is read by the control unit, or (ii) periodically.

[0133] In a 96th aspect of the present disclosure that can be combined with other aspects or portions thereof, the control unit is configured to use the corrected output from the pressure sensor of (ii) for at least one of (a) controlling a medical fluid pump actuator to pump within the patient's pressure limit, (b) determining a line occlusion state, or (c) determining a container empty state.

[0134] In a 97th aspect of the present disclosure that can be combined with any other aspect or portion thereof, the medical fluid system includes a medical fluid pump actuator, a medical fluid delivery set having a flexible sheet, a pressure sensor arranged such that when the medical fluid delivery set is loaded for operation by the medical fluid pump actuator, the flexible sheet is placed under tension through contact with the pressure sensor, and a control unit configured to precondition the flexible sheet for operation with the pressure sensor by applying pressure to the flexible sheet by the medical fluid pump actuator.

[0135] In a 98th aspect of the present disclosure that can be combined with any other aspect or portion thereof, the pressure applied during preconditioning is a fluid pressure.

[0136] In a 99th aspect of the present disclosure that can be combined with any other aspect or portion thereof, the pressure applied during preconditioning is a periodic up-and-down pressure.

[0137] In a 100th aspect of the present disclosure that can be combined with any other aspect or portion thereof, the pressure applied during preconditioning is from 100% to 150% of the maximum operating pressure supplied during treatment.

[0138] In a 101st aspect of the disclosure that can be combined with any other aspect or a part thereof, a medical fluid system includes a plurality of valves operable with a medical fluid delivery set, and a control unit causes the plurality of valves to be closed during preconditioning.

[0139] In a 102nd aspect of the disclosure that can be combined with any other aspect or a part thereof, a medical fluid system includes a medical fluid pump actuator, a medical fluid delivery set having a flexible sheet, a temperature sensor positioned and arranged to detect the temperature of a medical fluid flowing through the medical fluid delivery set, a pressure sensor arranged such that the flexible sheet is placed under tension via contact with the pressure sensor when the medical fluid delivery set is loaded for operation by the medical fluid pump actuator, and a control unit configured to use the output from the temperature sensor in a compensation algorithm that modifies the output from the pressure sensor.

[0140] In a 103rd aspect of the disclosure that can be combined with any other aspect or a part thereof, the control unit is configured to update a temperature compensation algorithm (i) each time the output from the pressure sensor is read by the control unit or (ii) periodically.

[0141] In a 104th aspect of the disclosure that can be combined with any other aspect or a part thereof, the control unit is configured to use the corrected output from the pressure sensor for at least one of (i) controlling the medical fluid pump actuator to pump within the patient's pressure limits, (ii) determining a line occlusion state, or (iii) determining a container empty state.

[0142] In a 105th aspect of the present disclosure that can be combined with any other aspect or a part thereof, a dialysis device operable with a disposable set having at least one container includes a pump actuator operable to pump dialysis fluid in and / or from at least one container, a weight plate arranged to support the at least one container, a plurality of load cells arranged to support the weight plate, a linear actuator arranged to apply a force to the weight plate, a calibration load cell arranged to measure the force applied by the linear actuator, and a control unit operably communicating with the load cells, the linear actuator, and the calibration load cell, the control unit being configured to cause the linear actuator to apply a force to the weight plate, compare the resulting outputs from the load cells and the calibration load cell, and determine a calibration factor from the comparison to cancel out future outputs from the load cells.

[0143] In a 106th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the load cells are arranged to be at least substantially equidistant from the center of mass of the weight plate.

[0144] In a 107th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the calibration load cell is arranged to be at least substantially at the center of mass of the weight plate.

[0145] In a 108th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the linear actuator includes a motor and a lead screw, or a linear stepper motor.

[0146] In a 109th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the linear actuator is arranged between the calibration load cell and the weight plate.

[0147] In a 110th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the control unit is configured to sum the outputs resulting from the operating load cell in order to compare with the output resulting from the calibration load cell.

[0148] In a 111th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the calibration coefficient for canceling the future output from the operating load cell is applied to the sum of the future outputs from the operating load cell.

[0149] In a 112th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the calibration coefficient includes the output resulting from the calibration load cell divided by the sum of the outputs resulting from the operating load cell.

[0150] In a 113th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the linear actuator is mechanically in communication with the weight plate, and the control unit is configured to cause the linear actuator to apply a tensile force to the weight plate.

[0151] In a 114th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the control unit is configured to cause the linear actuator to apply a force to the weight plate before the container is placed on the weight plate.

[0152] In a 115th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the control unit is configured to cause the linear actuator to apply a force to the weight plate during processing while the container is supported by the weight plate.

[0153] In a 116th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the control unit is operably in communication with the pump actuator, and at least the operating duration of the pump actuator is controlled using the offset output from the operating load cell.

[0154] In a 117th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the control unit is configured not to supply force to the linear actuator during the duration of the operation.

[0155] In a 118th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the control unit is configured to determine the mass or volumetric flow rate during treatment using two or more offset outputs from the operating load cell.

[0156] In a 119th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the dialysis system includes a disposable set including a pumping unit and at least one container, and a dialysis device. The dialysis device includes a pump actuator operable with the pumping unit to pump dialysis fluid in and / or from at least one supply container, a weight plate arranged to support at least one container, a plurality of operating load cells arranged to support the weight plate, a linear actuator arranged to apply a force to the weight plate, a calibration load cell arranged to measure the force applied by the linear actuator, and a control unit operably communicating with the operating load cell, the linear actuator, and the calibration load cell. The control unit is configured to cause the linear actuator to apply a force to the weight plate, compare the resulting outputs from the operating load cell and the calibration load cell, and determine a calibration coefficient from the comparison to cancel out future outputs from the operating load cell.

[0157] In a 120th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the control unit is configured to sum the resulting outputs from the operating load cell for comparison with the resulting output from the calibration load cell.

[0158] In a 121st aspect of the present disclosure that can be combined with any other aspect or a part thereof, a calibration factor for offsetting the output resulting from the operating load cell is applied to the sum of the outputs resulting from the operating load cell.

[0159] In a 122nd aspect of the present disclosure that can be combined with any other aspect or a part thereof, at least one container includes at least one supply container, the pump actuator is operable with a pumping unit to pump fresh dialysate from at least one supply container, and the control unit is configured to determine the amount of fresh dialysate delivered using at least two offset outputs from the operating load cell.

[0160] In a 123rd aspect of the present disclosure that can be combined with any other aspect or a part thereof, at least one container includes at least one drain container, the pump actuator is operable with a pumping unit to pump used dialysate to at least one drain container, and the control unit is configured to determine the amount of used dialysate delivered using at least two offset outputs from the operating load cell.

[0161] In a 124th aspect of the present disclosure that can be combined with any other aspect or a part thereof, the control unit is configured to determine the amount of fresh dialysate delivered to the patient or the amount of used dialysate removed from the patient using at least two offset outputs from the operating load cell.

[0162] In a 125th aspect of the present disclosure, any of the features, functions, and alternatives described in relation to any one or more of FIGS. 1 to 13 can be combined with any of the features, functions, and alternatives described in relation to any other of FIGS. 1 to 13 and / or any of the aspects listed herein.

[0163] Accordingly, an advantage of the present disclosure is to provide an accurate APD system that uses a relatively simple and cost-effective peristaltic pump.

[0164] Another advantage of the present disclosure is to provide an APD system that eliminates certain seal problems present in known APD systems.

[0165] A further advantage of the present disclosure is to provide an APD pump drive system that eliminates bulky pneumatic equipment associated with certain APD systems.

[0166] Yet another advantage of the present disclosure is to provide an APD pump drive system that reduces noise compared to pneumatic systems.

[0167] Yet another advantage of the present disclosure is to provide an APD system that manages the flow of peritoneal dialysis fluid to be within safe and comfortable patient pressure limits.

[0168] Yet another advantage of the present disclosure is to provide an APD system having a simplified disposable set.

[0169] A further advantage of the present disclosure is to provide an APD system having accurate pressure and weight sensing.

[0170] Furthermore, an advantage of the present disclosure is to provide an APD system that simplifies the removal of used dialysis fluid for accommodating the drain for the patient.

[0171] Additional features and advantages will be described in the following detailed description and the drawings, and will become apparent therefrom. It should be noted that the features and advantages described herein are not all-inclusive, and in particular, many additional features and advantages will be apparent to those skilled in the art upon consideration of the drawings and the description. Also, any particular embodiment need not have all of the advantages listed herein, and it is expressly contemplated that the individual advantageous embodiments will be claimed separately. Further, note that the language used herein has been selected primarily for readability and for purposes of explanation, and is not intended to limit the scope of the subject matter of the present invention. This specification also provides, for example, the following. (Item 1) A medical fluid system (10), wherein the medical fluid system (10) comprises a medical fluid pump actuator (60), a medical fluid conveyance set (120) having a flexible sheet (136), a temperature sensor (38) positioned and arranged to detect the temperature of the medical fluid flowing through the medical fluid conveyance set (120), pressure sensors (36a, 36b) positioned and arranged to contact the flexible sheet (136) when the medical fluid conveyance set (120) is loaded for operation with the medical fluid pump actuator (60), and a control unit (50) and is configured such that the control unit (50) performs: (i) preconditioning the flexible sheet (136) for operation with the pressure sensors (36a, 36b) by causing the medical fluid pump actuator (60) to apply pressure to the flexible sheet (136); and (ii) using the output from the temperature sensor (38) in a compensation algorithm that corrects the output from the pressure sensors (36a, 36b). Medical fluid system (10). (Item 2) The medical fluid pump actuator (60) of the medical fluid system (10) according to Item 1, wherein the medical fluid pump actuator (60) is a peristaltic pump actuator. (Item 3) The medical fluid system (10) according to Item 1, wherein the pressure sensors (36a, 36b) are arranged such that when the medical fluid conveyance set (120) is loaded for operation with the medical fluid pump actuator (60), the flexible sheet (136) is placed under tension through contact with the pressure sensors (36a, 36b). (Item 4) The medical fluid system (10) according to Item 1, wherein the pressure sensors (36a, 36b) are operable with portions of pressure pods (150a, 150b) of the flexible sheet (136). (Item 5) The medical fluid system (10) according to Item 1, wherein the pressure applied during (i) is a fluid pressure. (Item 6) The medical fluid system (10) according to Item 1, wherein the pressure applied during (i) is a periodic up-and-down pressure. (Item 7) The medical fluid system (10) according to item 1, wherein during (i), the pressure applied is from 100% to 150% of the maximum operating pressure supplied during the treatment. (Item 8) The medical fluid system (10) according to item 1, comprising a plurality of valves (34a to 34e) operable with the medical fluid delivery set (120), wherein the control unit (50) causes the plurality of valves (34a to 34e) to be closed during (i). (Item 9) The compensation algorithm is V T =V 0 +gT, where V 0 is the output from the pressure sensors (36a, 36b), V T is the corrected pressure output, g is the temperature scaling factor, T is the detected temperature, The medical fluid system (10) according to item 1. (Item 10) The medical fluid system (10) according to item 1, wherein the control unit (50) is configured to update the compensation algorithm for temperature whenever the output from the pressure sensors (36a, 36b) is read by the control unit (50) or (ii) periodically. (Item 11) The medical fluid system (10) according to item 1, wherein the control unit (50) is configured to use the corrected output from the pressure sensors (36a, 36b) in (ii) for at least one of (a) controlling the medical fluid pump actuator (60) to pump within the patient's pressure limit, (b) determining a line occlusion state, or (c) determining a container empty state. (Item 12) A medical fluid system (10), the medical fluid system (10) comprising a medical fluid pump actuator (60), a medical fluid delivery set (120) having a flexible sheet (136), pressure sensors (36a, 36b), wherein the pressure sensors (36a, 36b) are arranged such that when the medical fluid delivery set (120) is loaded for operation with the medical fluid pump actuator (60), the flexible sheet (136) is placed under tension through contact with the pressure sensors (36a, 36b), a control unit (50) and is provided with The medical fluid system (10) is such that the control unit (50) is configured to precondition the flexible sheet (136) for operation with the pressure sensors (36a, 36b) by causing the medical fluid pump actuator (60) to apply pressure to the flexible sheet (136). (Item 13) The medical fluid system (10) according to item 12, wherein the pressure applied during the preconditioning is a fluid pressure. (Item 14) The medical fluid system according to item 12, wherein the pressure applied during the preconditioning is a periodic up-and-down pressure. (Item 15) The medical fluid system (10) according to item 12, wherein the pressure applied during the preconditioning is from 100% to 150% of the maximum operating pressure supplied during treatment. (Item 16) The medical fluid system (10) according to item 12, including a plurality of valves (34a to 34e) operable with the medical fluid conveyance set (120), wherein the control unit (50) closes the plurality of valves (34a to 34e) during the preconditioning. (Item 17) A medical fluid system (10), comprising: a medical fluid pump actuator (60); a medical fluid conveyance set (120) having a flexible sheet (136); a temperature sensor (38) positioned and arranged to detect the temperature of the medical fluid flowing through the medical fluid conveyance set (120); pressure sensors (36a, 36b) arranged such that when the medical fluid conveyance set (120) is loaded for operation with the medical fluid pump actuator (60), the flexible sheet (136) is placed under tension through contact with the pressure sensors (36a, 36b); a control unit (50); and is characterized in that the control unit (50) is configured to use the output from the temperature sensor (38) in a compensation algorithm for correcting the output from the pressure sensors (36a, 36b). (Item 18) The compensation algorithm is V T =V 0 +gT, where V 0 is the output from the pressure sensors (36a, 36b), V T is the corrected pressure output, g is the temperature scaling factor, T is the detected temperature, The medical fluid system (10) according to item 17. (Item 19) The control unit (50) is configured to update the compensation algorithm for temperature whenever the output from the pressure sensors (36a, 36b) is read by the control unit (50) or (ii) periodically, The medical fluid system (10) according to item 17. (Item 20) The control unit (50) is configured to use the corrected output from the pressure sensors (36a, 36b) for at least one of (i) controlling the medical fluid pump actuator (60) to pump within the patient's pressure limit, (ii) determining a line occlusion state, or (iii) determining a container empty state. The medical fluid system (10) according to item 17.

Brief Description of the Drawings

[0172]

Figure 1

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Figure 2

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Figure 3

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Figure 4

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Figure 5

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Figure 6

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Figure 7

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Figure 8

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Figure 9

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Figure 10

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Figure 11

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Figure 12

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Figure 13

DETAILED DESCRIPTION OF THE INVENTION

[0185] (System Overview) Referring now to the drawings, and in particular to FIG. 1, an embodiment of the system 10 includes an automated peritoneal dialysis (“APD”) cycler 20 having a housing 22. The cycler 20 uses a peristaltic pump in one embodiment, and the peristaltic pump operates a disposable set 120. All of the rigid and flexible tube portions of the disposable set 120 can be made from one or more plastics (e.g., polyvinyl chloride (“PVC”), or non-PVC materials such as polyethylene (“PE”), polyurethane (“PU”) or polycarbonate (“PC”)). The housing 22 of the cycler 20 can be made from any of the plastics described above, and / or metal, such as stainless steel, steel and / or aluminum.

[0186] In the illustrated embodiment, the housing 22 includes a hinged door 24, and the hinged door 24 has a series of holes or slots 26a, 26b, 26c, 26d, and 26e, which are respectively for the tubes (122a to 122e) of the disposable set 120 that extend from the inside of the housing 22 to the outside of the housing. Although shown as elongated slots, the apertures (26a to 26e) can alternatively be holes. However, the slots (26a to 26e) are advantageous for allowing the door 22 to be hingedly opened without placing the tubes (122a to 122e) under excessive tension. In an embodiment, the tubes (122a to 122e) are pre-connected to the disposable pump cassette shown below and sterilized therewith. The distal ends of the tubes (122a to 122e) are removed from the sterile caps during the treatment setup and secured to the containers or bags (124a to 124d) of the disposable set 120 (line 122e is the patient line). The container or bag 124a can be a drain container or bag. The containers or bags 124b and 124c can be primary fresh dialysate supply containers or bags. The container 124d can be the final fill container or bag, which holds a different prescription of fresh dialysate (e.g., 2 to 3 liters of icodextrin), and the fresh dialysate is formulated to remain inside the patient's peritoneal cavity after the patient disconnects from the disposable set 120.

[0187] In the illustrated embodiment, the door 24 is arranged vertically and thus holds the disposable cassette of the set 120 perpendicular to the working surface of the housing within the housing 22 of the cycler 20. The door 24 is arranged adjacent to the user interface portion of the cycler 20, and the cycler includes a control unit 50 having one or more processors 52, one or more memories 54, and a video controller 56, and the video controller interfaces the one or more processors 52 and the one or more memories 54 with the user interface 58. The user interface 58 may include a touch screen and / or electromechanical buttons (such as membrane switches) for inputting user commands and providing instructions, alerts, and alarms. Providing the user interface 58 adjacent to the door 24 of the housing 22 allows a patient or other user to normally interact with one surface of the device 20 for inputting commands, receiving data, and loading / unloading the disposable cassette. The user interface 58 may alternatively or additionally be a remote user interface via, for example, a tablet or smartphone. The control unit 50 may also include a transceiver and a wired or wireless connection to a network (not shown, such as the Internet) for transmitting treatment data to a server of a physician or clinician interfaced with the computer of the physician or clinician and receiving prescription instructions / changes from the server of the physician or clinician. The data transmitted to the computer of the physician or clinician may be analyzed and / or converted into or used to form other data useful for analysis. Such data conversion may alternatively or additionally be performed in the control unit 50 of the cycler 20.

[0188] Figure 1 shows that system 10 in one embodiment also includes a bag shelf enclosure 40 that serves multiple purposes. The bag shelf enclosure 40 is sized such that the cycler 20 can be stored inside the enclosure when not in use. In the illustrated embodiment, the bag shelf enclosure 40 includes a rotatably hinged handle 42 that enables a user to transport the enclosure with the cycler 20 stored inside. As shown in FIG. 1, the bag shelf enclosure 40 is also sized such that the bag shelf enclosure can be set on top of the cycler (in one embodiment, on top of the weight plate, as will be described in detail below) when the cycler 20 is in use. The bag shelf holds a plurality of containers or bags (124a - 124d), such as a plurality of supply containers (124b - 124d) and one or more drain containers 124a. As shown, the containers or bags are held within the enclosure 40 and on the outer upper surface of the enclosure.

[0189] The bag shelf enclosure 40 may include color - coded markers 44a - 44d provided in positions for loading containers or bags having lines that extend into the cycler 20 through slots or apertures 26a - 26d, and the slots or apertures have similarly color - coded markers or boundaries. The matching color - coded markers 44a - 44d and slot boundaries facilitate a patient or caregiver in identifying which bag and line belong to which position on the bag shelf enclosure 40. For example, the boundary of marker 44a and slot 26a may be green to indicate the drain line 122a and drain container 124a, and the desired position of the drain container. The boundaries of markers 44b and 44c and slots 26b and 26c may be blue to indicate the primary supply lines 122b, 122c and supply containers 124b, 124c, and the desired positions of the supply containers. The boundary of marker 44d and slot 26d may be red to indicate the last fill line 122d and last fill container 124d, and the desired position of the last fill container.

[0190] (Drain / Purge) It is conceivable to use the supply container or bag, such as the primary supply containers or bags 124b and 124c, later as a drain container or bag to reduce the overall disposable cost. For example, assume that the patient is full of effluent at the start of the treatment. The effluent is first drained from the patient and delivered to the initially empty drain container 124a. Next, the first patient fill is delivered from the first primary supply container 124b to the patient and, after a specified dwell period, is delivered to the same drain container 124a (or a different drain container depending on the size of the drain container). In an embodiment, the drain container 124a, and the primary supply containers 124b and 124c are larger 6 - liter containers for holding fresh and used dialysate for multiple cycles. The drain container 124a is used to receive the effluent until the first supply container 124b is empty, after which the first supply container receives the effluent after a dwell period using the PD fluid supplied from the second supply container 124c. The first supply container 124b is used to receive the patient effluent until the second supply container 124c is empty, likely over multiple patient fills, dwells, and drains. At that point, the patient may receive the final fill of a different prescription of peritoneal dialysis fluid from the last fill container 124d, which remains within the patient until the next night's treatment or perhaps until the daytime exchange. If the second supply container 124c is empty at the end of the treatment, it can be used as the first empty drain container at the start of the next treatment, further reducing disposable waste and cost.

[0191] In one example, the containers (124a - 124d) can be used as follows if the patient is initially full: Initial drain → Drain container 124a Supply container 124b → First fill → Drain container 124a Supply container 124b → Second fill → Drain container 124a Supply container 124c → Third fill → Supply container 124b Supply container 124c → Fourth fill → Supply container 124b Final filling container 124d - Final filling

[0192] In one example, the containers (124a to 124d) can be used as follows if they are initially empty for a patient: Supply container 124b → First filling → Drain container 124a Supply container 124b → Second filling → Drain container 124a Supply container 124c → Third filling → Supply container 124b Supply container 124c → Fourth filling → Supply container 124b Final filling container 124d - Final filling

[0193] At the end of the treatment, a plurality of containers or bags (e.g., containers 124a, 124b) are filled with the effluent. The remaining supply container 124c can also hold the remaining fresh dialysis fluid. To prevent the patient or caregiver from having to transport a full drain bag to a house drain, such as a toilet, sink, or bathtub, the control unit 50 of the cycler 20 is programmed to remove the patient line 122e from the patient transfer set and prompt the user to carry the distal end of the patient line 122e to the house drain. Optionally, a reusable extension line 122f can be connected to the distal end of the patient line 122e to reach the house drain. The patient or caregiver then presses the drain button on the user interface 58, at which time the cycler 20 actuates a pump actuator, such as a peristaltic pump actuator, in a direction to draw the used dialysis fluid or effluent from each of the drain containers 124a, 124b (one or more of which can be the original supply containers) and pump the used dialysis fluid through the patient line 122e (and optionally the extension line 122f) to the house drain. The remaining fresh dialysis fluid is similarly removed from the supply container 124c. The drain button in an embodiment is displayed only at the end of the treatment when the button is needed, e.g., via a touch screen display. Alternatively, the drain button can be a membrane switch that is enabled only at the end of the treatment when the button is needed. Further, regardless of its type, the drain button can be displayed and / or enabled only after the patient presses a confirmation button provided by the user interface 58 in response to a prompt by the user interface to confirm that the patient line 122e / 122f extends to the house drain.

[0194] The control unit 50 of the cycler 20 detects when each drain container 124a, 124b is empty (e.g., via a weighing scale and / or pressure sensor operating with the pressure pods of the disposable cassette, as will be described in detail below), and automatically switches a valve actuator, such as a pinch valve actuator, to sequence between the drain containers 124a, 124b (and optionally the supply container 124c) until each is empty. In particular, the cycler 20 includes a patient valve actuator operating with a patient valve seat provided by the disposable set 120 and a drain valve actuator operating with a drain valve seat provided by the disposable set, and the control unit 50 is configured to cause the patient valve actuator and the drain valve actuator to allow flow through the drain valve seat and the patient valve seat and to pump used dialysate from the drain container through the patient line to the house drain. It should be understood that multiple drain containers, one or more of which may have been a previous supply container, can be drained simultaneously over the same period or overlapping periods, for example to save time.

[0195] It is also conceivable for the control unit 50 to search for any remaining fresh dialysate in any remaining supply containers, e.g., containers 124c and 124d, and to pump the remaining fresh dialysate to a pump actuator to accommodate the drain via the patient line. In this way, when the patient disconnects the connection from the patient line 122e and presses the drain button, the patient can assume that all fresh and used dialysate is being pumped to the house drain, and thus can freely start the patient's day.

[0196] System 10 is described in this section as pumping effluent or remaining fresh dialysate to a house drain, but in alternative embodiments, it should be understood that the control unit 50 can pump any remaining fluid (fresh or used) from any container (124a - 124d) to any other container (124a - 124d). In an embodiment, after the patient disconnects from the patient line 122e, the patient places the distal end of the patient line in a priming holder (not shown) disposed in the housing 22 of the cycler 20 and confirms this action at the user interface 58. The distal end of the patient line 122e remains open to the atmosphere. Next, the control unit 50 executes a sequence in which all the fluid currently present in the patient line 122e is pumped to a desired destination container (124a - 124d) and the patient line 122e is filled completely or almost completely with air. Then, the control unit 50 causes any dialysate (fresh or used) delivered to any container (124a - 124d) to be moved through the peristaltic pump actuator 60 that rotates in the patient fill direction by a known number of strokes to push the amount of fluid into a safe portion of the patient line 122e through the in - line fluid heating path 144 so that the fluid does not spill from the end of the patient line. Next, the control unit 50 reverses the direction of the peristaltic pump actuator 60 to rotate in the patient drain direction during a known number of strokes and changes the valve state of the associated valve actuator to extrude that amount of fluid through the safe portion of the patient line 122e and the in - line fluid heating path 144 to the desired destination container (124a - 124d). And the control unit 50 repeats the pumping and reverse - pumping operations until the desired amount of fresh dialysate or used dialysate is moved from a desired source container (124a - 124d) to a desired destination container (124a - 124d).

[0197] (Auto - loader) Referring now to FIG. 2, an embodiment of the working surface 30 of the cycler 32 is shown. The working surface 30 of FIG. 1 is hidden behind the door 24. When the door 24 is opened, the working surface 30 as shown in FIG. 2 is exposed. To show how the working surface 30 is oriented in FIG. 1, the labels “upper,” “lower,” “user interface,” and “patient end” are shown in FIG. 2. The working surface 30 in the illustrated embodiment includes a heater 32 (such as a resistance plate that heats an in-line fluid heating path provided by a disposable cassette shown below). The working surface 30 also includes a plurality of valve actuators (34a through 34e), which include a drain line valve actuator 34a, main supply line valve actuators 34b and 34c, a final fill line valve actuator 34d, and a patient line valve actuator 34e. Embodiments of the valve actuators (34a through 34e) are shown in detail below. The working surface 30 also includes a plurality of pressure sensors (including a patient pressure sensor 36a and a pumping pressure sensor 36b). Embodiments of the pressure sensors 36a and 36b are likewise shown in detail below. At least one temperature sensor 38, such as a thermocouple or a thermistor, is also provided. The control unit 50, shown metaphorically in FIG. 2, controls the heater 32 and the valve actuators (34a through 34e) and receives inputs from the pressure sensors 36a, 36b, and the temperature sensor 38.

[0198] Figure 2 further shows that the peristaltic pump actuator 60 under the control of the control unit 50 is disposed on the working surface 30 of the cycler 20 and extends behind it. The pump actuator 60 may include a pump head 62 disposed on the working surface 30 and a driver or motor 64 disposed behind the working surface 30. The disposable cassette includes a peristaltic pump tube, and when loading the cassette, the user guides the peristaltic pump tube over the pump head 62 of the peristaltic pump actuator 60. During operation, the peristaltic pump actuator 60 compresses the peristaltic pump tube against the track 66 at a plurality of points. The operational proximity of the track 66 to the peristaltic pump actuator 60 makes it difficult to load the tube. Thus, the cycler 20 provides a movable track 66 that translates parallel to avoid interfering with the peristaltic pump actuator, for example via a linkage mechanism (not shown), when the door 24 of the cycler 20 is opened for a patient or caregiver to load the disposable cassette. After the cassette is loaded, closing the cycler door 24 translates the movable track 66 to an operable position that is directly adjacent to the peristaltic pump tube, for example via a linkage mechanism. In an alternative embodiment, a motor and lead screw assembly, or a linear actuator (e.g., a linear stepper motor not shown) is provided to automatically translate the track 66 parallel to avoid interfering with the peristaltic pump actuator 60 when a patient or caregiver opens the door 24 to load the cassette and to automatically translate the track 66 to an operable position when the door 24 is closed. In a further alternative embodiment, a motor and lead screw assembly, or a linear actuator (e.g., a linear stepper motor not shown) is provided, but the patient or caregiver instead presses one or more buttons on the user interface 58 to translate the track 66 parallel to avoid interference or to an operable position.

[0199] In an embodiment, the track 66 is mounted on a block or member 70, and the block or member 70 is movable parallel across the working surface 30 towards and away from the peristaltic pump actuator 60. In addition to the translational movement of the member 70 (and the track 66), the movable track 66 can also rotate about a pivot axis 72 provided at one end 66a of the track 66, and the pivot axis 72 is mounted on the translatable member 70. The other end 66b of the track 66 is spring-biased via a spring 74, such as a compression spring, confined between the track end 66b and the member 70. In the illustrated embodiment, the spring 74 is inserted onto a threaded bolt 76 that extends through the track end 66b and is threaded into the member 70. The threaded bolt 76 includes a head 76h that sets the end of the spring movement for the track 66, and the end of the movement can be adjusted in or out, respectively, by rotating the threaded bolt 76 clockwise or counterclockwise. In the illustrated embodiment, the spring 74 pushes the track 66 around the pivot axis 72 to a desired operating position around the peristaltic pump tube after the member 76 has been translated parallel towards the peristaltic pump actuator 60. The pivoting track 66 can absorb or tolerate variations due to tube tolerances and provide a damping effect that helps reduce noise.

[0200] Figures 2 and 3 show that the member 70 and the track 66 slide along a linear rail 68 formed or provided along the working surface 30. The member 70 includes on its underside a rail receiver (not visible) sized to fit into and operate with the linear rail 68. The rail receiver in the embodiment interacts with the linear rail 68, for example, via a tongue-and-groove fit, to hold the member 70 and the track 66 in which the linear rail 68 is slidably engaged along the working surface 30. Additionally or alternatively, Figure 3 shows that an elongated slot 78 can be formed in the member 70, and the elongated slot 78 receives bolts that can be loosely tightened, whereby the member 70 and the track 66 can slide along the working surface 30 while still being held on the surface.

[0201] Section IIIA of FIG. 3 shows the peristaltic pump tube 126 of the disposable set 120 when it is about to be loaded. The member 70 and the track 66 are in a fully retracted position or a non-obstructing position. Section IIIB of FIG. 3 shows that the peristaltic pump tube 126 is extended or is disposed in an operable position around the pump head 62 of the peristaltic pump actuator 60. The member 70 and the track 66 are again in a fully retracted position or a non-obstructing position. Section IIIC of FIG. 3 shows that the member 70 and the track 66 have been translated to an operable position parallel to the peristaltic pump tube 126 and the pump head 62 of the peristaltic pump actuator 60.

[0202] As described above, a purely mechanical linkage mechanism (not shown) can be provided, which pulls the member 70 and the track 66 to a fully retracted or non-obstructing position in Sections IIIA and IIIB of FIG. 3, for example, the linkage mechanism is actuated by the opening of the door 24. The linkage mechanism pushes the member 70 and the track 66 into an operable position in Section IIIC of FIG. 3, for example, the linkage mechanism is actuated by the closing of the door 24. Alternatively, an electric mechanism such as a linear actuator or a motor and a lead screw is provided to (i) automatically pull the member 70 and the track 66 to a fully retracted or non-obstructing position in Sections IIIA and IIIB of FIG. 3 when the door 24 is opened, and (ii) automatically push the member 70 and the track 66 into an operable position in Section IIIC of FIG. 3 when the door 24 is closed. Further alternatively, if it is desirable to be able to access the working surface 30 when the member 70 and the track 66 are in the operable position, for example, to perform both retracting and extending the member 70 and the track 66, or, in some cases, to extend the member 70 and the track 66 to the operable position only after being automatically pulled to the fully retracted position when the door 24 is opened, a button for actuating the electric mechanism can be provided on the user interface 58. The control unit 50 can be programmed to execute any such sequence.

[0203] As shown in the fully retracted sections IIIA and IIIB of FIG. 3, member 70 includes a base 70b that defines an arc having a radius that at least substantially matches the radius of track 66. The head 76h of bolt 76 is arranged to provide a stopper that stops the rotation of track 66 that occurs via spring 74 (e.g., by screwing bolt 76 outside of member 70) when the radius of track 66 at least substantially reaches and thus matches that of the arc of base 70b. As described above, track 66 is movable primarily to facilitate loading. A secondary advantage of the translational movement is adjustment of the track position to optimize the flexibility of the tube. Rotation via pivot axis 72 and spring 74 helps absorb tube tolerances and provides a damping effect that aids in noise reduction. Spring 74 is shown as a compression spring, but it should be understood that the spring could alternatively be a tension spring or other type of spring.

[0204] (Spring end effector) Referring now to FIGS. 4, 5A and 5B, there are shown any or all embodiments of pinch valve actuators (34a - 34e). A disposable cassette 130 (e.g., injection - molded or blow - molded plastic) provides valve seats (132a - 132e), and the valve seats (132a - 132e) each receive a pinch valve actuator (34a - 34e) for closing or occluding a fluid path 134 provided by the disposable cassette. In FIG. 4, the disposable cassette 130 is sealed (e.g., ultrasonically welded, heat - sealed, and / or solvent - bonded) and covered by a flexible sheet 136, e.g., flexible plastic, and the pinch valve actuators (34a - 34e) close the respective fluid paths 134 by pressing a portion of the flexible plastic against the respective valve seats (132a - 132e). The pinch valve actuators (34a - 34e) open the respective fluid paths 134 by retracting. As shown in FIG. 4, the openings of the valve seats (132a - 132e) extend through a rigid body 138 of the disposable cassette 130 and through ports (140a - 140e), and the ports (140a - 140e) extend in a direction opposite to the valve seats. Each line or tube (122a - 122e) is sealably connected to the respective port (140a - 140e), e.g., by ultrasonic welding, heat - sealing, and / or solvent - bonding. The lines or tubes (122a - 122e) extend from the disposable cassette 130 through the door 24 via respective slots or apertures (26a - 26e) as shown in FIG. 1.

[0205] As shown in FIG. 4, each of the pinch valves (34a through 34e) is driven by a linear actuator 80, which can be any suitable type of linear actuator, such as a linear stepping motor, that provides a required amount of movement (e.g., up to 10 mm) and a required amount of pressure cassette sheet closing force (e.g., 30 to 60 Newtons (“N”) or less) under the control of the control unit 50. In the illustrated embodiment, the linear actuator 80 is mounted on the inner wall 46 or other internal structure within the housing 22 of the cycler 20, so that the valve plunger 84 connected to the output shaft 82 of the linear actuator 80 extends through the hole 30h in the working surface 30 to just meet the flexible valve membrane 48, e.g., flexible silicone, bolted to the working surface 30. The linear actuator 80 drives the valve plunger 84 to press the flexible membrane 48 and a portion of the cassette sheet 136 against their respective cassette valve seats (132a through 132e). The linear actuator 80 allows the sheet to be removed from their respective cassette valve seats (132a through 132e) by retracting the valve plunger 84, e.g., via its own elasticity and positive fluid pressure.

[0206] As shown in FIGS. 5A and 5B, in one embodiment, the valve plunger 84 includes a proximal end effector 86 coupled to the linear actuator 80 and a distal end effector 90 slidably coupled to the proximal end effector 86. As shown in FIG. 5B, the proximal end effector 86 has a larger diameter portion 86a and a smaller diameter portion 86b. The distal end effector 90 includes or defines a cylindrical opening 92 that slidably receives the smaller diameter portion 86b of the proximal end effector 86. In the illustrated embodiment, the spring 98 is disposed between a step 86c that transitions between the larger diameter portion 86a and the smaller diameter portion 86b and a proximal edge 90p of the distal end effector 90. Thus, the spring 98 is constrained by the smaller diameter portion 86b of the proximal end effector 86. FIGS. 5A and 5B show that the outer diameter of the distal end effector 90 can be at least substantially equal to the outer diameter of the larger diameter portion 86a of the proximal end effector 86.

[0207] One of the proximal end effector 86 or the distal end effector 90 defines at least one groove, and the other of the proximal end effector or the distal end effector includes at least one spring arm that mechanically fits (e.g., snap fits) into the at least one groove to slidably attach the end effectors to each other. In the illustrated embodiment, the proximal end effector 86 defines at least one groove 88, and the distal end effector 90 includes or defines a plurality of spring arms 94a, 94b... 94n that mechanically fit (e.g., snap fit) into the at least one groove 88. If it is desirable for the distal end effector 90 not to spin relative to the proximal end effector 86, a separate groove 88 can be defined for each spring arm 94a, 94b... 94n. If it is not a problem, instead a single annular groove 88 can be provided. In either case, the length of the at least one groove 88 is sized to provide the travel length of the distal end effector 90 relative to the proximal end effector 86, which is greater than the uncompressed length of the spring 98.

[0208] Spring 98 can be a wave or compression spring. One acceptable travel length of spring 98 is 2.9 mm. In an embodiment, spring 98 is configured to provide a sealing force of 25 N necessary to properly seal cassette sheet 136 against the valve seats (from 132a to 132e) after a compression travel of about 1.4 mm. Spring 98 can apply a force of up to 51 N at the contact height, and linear actuator 80 is selected to have at least a slightly higher peak force.

[0209] Spring 98 is arranged to bias distal end effector 90 outwardly relative to proximal end effector 86. The variable distance provided by spring 98 allows pinch valves (from 34a to 34e) to first contact cassette sheet 136 with a smaller closing force (via flexible membrane 48), and the closing force steadily increases as spring 98 is compressed. Flexible membrane 48 is fixed to working surface 30 so as to cover the end of distal end effector 90. When spring 98 is fully compressed, cassette sheet 136 and the valve seats (from 132a to 132e) experience the full closing force of linear actuator 80 and spring 98. Thus, spring 198 provides a force buffer that helps protect flexible membrane 48 over multiple treatments and cassette sheet 136 over a single treatment. Spring 98 can also help with tolerances of disposable cassette 130 and variations due to its loading, and can further enable a smaller or less expensive linear actuator 80.

[0210] (Disposable Cassette / Valve Seat) Referring now to FIGS. 6 through 10, the disposable cassette 130 in the illustrated embodiment provides a plurality of valve seats that can include a patient line valve seat 132e, first and second supply line valve seats 132b, 132c, a final fill line valve seat 132d, and a drain line valve seat 132a. In the embodiment shown in FIGS. 6 and 9, the patient line valve seat 132e is fluidly separated from the first peristaltic tube port 142a by an in-line fluid heating path 144, such as a serpentine path. When the disposable cassette 130 is attached for operation, the in-line fluid heating path 144 is positioned adjacent to a heater 32, such as the resistive plate heater shown in FIG. 2. FIG. 9 shows that the flexible sheet 136 is sealed to the rigid body 138 so as to cover the fluid heating path 144, enabling heat to be transferred through the thin sheet to fresh dialysate moving through the path.

[0211] FIGS. 6 and 9 show that in one embodiment, each of the first and second supply line valve seats 132b, 132c, the final fill line valve seat 132d, and the drain line valve seat 132a is disposed within a common well 146 that is in fluid communication with the second peristaltic tube port 142b. The peristaltic pump tube 126 is attached (e.g., ultrasonically welded, heat sealed, and / or solvent bonded) to the tube ports 142a and 142b. Thus, fresh dialysate can be pumped in a first direction from any of the supply containers (124b through 124d) for the first and second supply line valve seats 132b, 132c or the final fill line valve seat 132d, through the common well 146 and the in-line fluid heating path 144, and in the in-line fluid heating path 144, the fresh dialysate is heated and then delivered to the patient from the patient line valve seat 132e. Used dialysate or effluent can be pumped from the patient, in a second direction, through the patient line valve seat 132e and the in-line fluid heating path 144 (where the used dialysate is not heated) into the common well 146 and from the drain line valve seat 132a to the drain container 124a.

[0212] The common well 146 simplifies the fluid path of the cassette 130. The drain line valve seat 132a is disposed closest to the peristaltic tube port 142b, such that spent dialysate travels the minimum distance within the well 146 before reaching the drain line valve seat. FIG. 8 showing the non-operating side of the disposable cassette 130 shows the drain port 140a, the supply container ports 140b, 140c, and the final fill container port 140d extending from the rigid body 138 on the other side from the common well 146. Again, the drain port 140a to which the drain line 122a is ultrasonically welded, heat sealed and / or solvent bonded is disposed directly adjacent to the peristaltic tube port 142b, such that spent dialysate is removed from the common well 146 as quickly as possible to reduce mixing with the fresh dialysate remaining within the well. The supply container lines 122b, 122c, the last fill container line 122d, and the patient line 122e are likewise ultrasonically welded, heat sealed and / or solvent bonded to the ports of the supply container ports 140b, 140c, the last fill container port 140d, and the patient line port 140e, respectively.

[0213] Figures 7 and 10 show that any of the valve seats (132a to 132e) described herein may include a tapered sealing surface 152 surrounded by a plurality of displacement ribs (154a to 154f), the displacement ribs may extend from the rigid body 138 of the disposable cassette 130, and at least some of the displacement ribs (154a to 154f) are shown to be spaced apart by a gap G, the gap G preventing or alleviating unwanted occlusion of the tapered sealing surface 152 by the flexible sheet 136 and allowing fresh or used dialysis fluid to flow through the gap G. The displacement ribs (154a to 154f) may be completely separated from each other (see Examples XC to XE in FIG. 10), or may extend from a common cylindrical base (see Examples XA and XB in FIG. 10). The displacement ribs (154a to 154f) may also be separated from the tapered sealing surface 152 (see Examples XB, XC and XE in FIG. 10), or may extend from or be connected to the outer edge of the tapered sealing surface (see Examples XA and XD in FIG. 10). The displacement ribs (154a to 154f) help guide the pinch valve plunger 84 towards the center of the valve seat (132a to 132e), while providing a certain amount of elasticity or play between the pinch valve plunger and the valve seat. In an embodiment, the tapered sealing surface 152 tapers to form a funnel shape leading to an opening that allows fresh or used dialysis fluid to flow into or out of the valve seat (132a to 132e). In an embodiment, the opening extends through ports (140a to 140e) disposed on the other side of the rigid body 138 of the disposable cassette 130 (FIG. 8). The tapered sealing surface 152 may also include or define one or more circular seal rings 156 that push the flexible sheet 136 in when the flexible sheet is closed by the pinch valves (34a to 34e).

[0214] In an embodiment, the first or patient pressure sensing pod 150a is disposed within the disposable cassette 130 immediately adjacent to the patient line valve seat 132e. When the disposable cassette 130 is loaded, the patient pressure sensing pod 150a is against the first or patient pressure sensor 36a, and the first or patient pressure sensor 36a outputs to the cycler control unit 50. The output of the patient pressure sensor 36a can be used to control the pumping pressures of the positive and negative pressures experienced by the patient such that they are within a safe pressure limit, for example, a positive pressure of 0.21 bar (3 psig) and a negative pressure of -0.10 bar (-1.5 psig). The second or pumping pressure sensing pod 150b is disposed within the disposable cassette 130 between the common well 146 and the second peristaltic tube port 142b. When the disposable cassette 130 is loaded, the pumping pressure sensing pod 150b is placed adjacent to the second or pumping pressure sensor 36b, and the second or pumping pressure sensor 36b outputs to the cycler control unit 50. The output of the pumping pressure sensor 36b can be used to detect blockages in the supply and drain lines and / or empty states of the supply and drain containers. For example, a sudden increase in positive pressure from the pumping pressure sensor 36b can indicate a blockage in the drain line 122a or the patient line 122e. In another example, a sudden increase in negative pressure from the pumping pressure sensor 36b can indicate (i) a blockage in the patient line 122e or the supply line (from 122b to 122d), (ii) an empty state of the supply container 124b, 124c, or the last filling container 124d during treatment, or, (iii) an empty state of the supply container 124b, 124c, the last filling container 124d, or the drain container 124a at the end of treatment when attempting to drain the remaining unused or used treatment fluid.

[0215] The disposable cassette 130 may also include one or more regions 148, and the one or more regions 148 are adjacent to a thermocouple or other type of temperature sensor 38 that outputs to the control unit 50 when mounted for operation. The temperature sensing region 148 may be disposed, for example, at an end of the in-line fluid heating path 144 that is directly adjacent to the patient pressure sensing pod 150a, such that the outlet temperature of the fresh dialysate to the patient is monitored and controlled, for example, to a desired temperature, such as body temperature or 37° C., via a proportional, integral, derivative (“PID”) routine executed by the control unit 50 using feedback from the temperature sensor 38. A second temperature sensor and associated cassette temperature region (not shown) may be disposed to detect the temperature at the inlet of the in-line fluid heating path 144 as needed, which may similarly provide useful information for the PID routine.

[0216] FIG. 6 shows the disposable cassette 130 disposed vertically when loaded for operation against the working surface 30, and the cassette includes a plurality of mechanisms that enhance priming and air handling. Referring further to FIG. 1, it should be understood that an important feature of the overall system 10 to prevent air from reaching the patient is the position of the fresh dialysate supply containers or bags (124b and 124c) relative to the last fill container or bag 124d, and those positions are higher than the position where the disposable cassette 130 is loaded against the working surface behind the door 24. Here, air tends to remain within the containers or bags (124b to 124d) and not be delivered to the disposable cassette 130. Although not shown, it is contemplated to provide a structure within and above the bag shelf enclosure 40 that raises the rear end of each container or bag (124b to 124d) relative to the front discharge end of the container. In this way, air tends to move away from the connection of each bag's respective tube (122b to 122d) and toward the rear of the container (124b to 124d).

[0217] It is also conceivable to arrange an air sensor or detector (not shown), which may be an ultrasonic sensor having emitter and receiver pairs on both sides of the holes or slots (26b to 26d), as shown in FIG. 1. The air sensor or detector outputs their output signals to a control unit 50 that monitors them. When air is detected, the control unit 50 (i) stops the peristaltic pump actuator 60 from pumping further towards the patient, (ii) closes the corresponding supply valve seats (132b to 132d) shown in FIG. 6, (iii) opens the drain valve seat 132a, and (iv) reverses the peristaltic pump actuator 60 to push the dialysis fluid with entrained air into the drain line 122a and the drain container 124a.

[0218] FIG. 6 shows that the drain valve seat 132a is located higher than the supply valve seats (132b to 132d) to help air move towards the drain valve seat. Further, the upper part of the common well 146 is provided with an inclined surface 146r for guiding air upward towards the drain valve seat 132a. FIG. 6 further shows that the pressure sensing pod 150b provides an inlet lower than the top of the inclined surface 146r such that air is urged to float away from the pressure sensing pod 150b towards the drain valve seat 132a. FIG. 6 also shows that the outlets of the patient and the pressure sensing pods 150a and 150b are directed upward and to a relatively high position, whereby air tends to leave the pods and assist in the accuracy of the fresh used dialysis fluid pressure measurement.

[0219] To assist priming, the serpentine fluid heating path 144 is serpentined upward to help air exit the disposable cassette 130 during priming through the patient line valve seat 132e and the patient line 122e to the atmosphere. The patient line valve seat 132e, like the drain line valve seat 132a, is positioned relatively high when the disposable cassette 130 is loaded for operation. During priming, the distal end of the patient line 122e is held within a priming holder (not shown) disposed on the housing 22 of the cycler 20. An additional air detector or sensor (not shown), such as an ultrasonic sensor, that outputs to the control unit 50 can be incorporated into the priming holder to detect when the patient line 122e has been completely primed with fresh dialysate. It is also contemplated to dispose an additional air sensor or detector (not shown) for the patient line, which can be an ultrasonic sensor having a pair of emitter and receiver disposed on either side of the patient line holes or slots 26e shown in FIG. 1. The additional air sensor or detector outputs its output signal to the control unit 50 that monitors it. If air is detected in the patient line 122e, the control unit 50 executes the air purge procedures (i) through (iv) to push the air through the fluid heating path 144 into the drain container or bag 124a.

[0220] (Pressure sensor) Referring now to FIG. 11, in one embodiment, the cycler 20 of the system 10 mounts the pressure sensors 36a, 36 on or associated with the working surface 30 of the cycler such that they are within the holes 30h of the working surface 30. Thereby, when the disposable cassette 130 is loaded for operation, the cassette sheet 136 (which can be either polyvinyl chloride (“PVC”) or any of the other polymers listed herein) is contacted by the pressure sensors 36a, 36b and placed under tension, generating a baseline or preload force Fp measured by the pressure sensors. FIG. 11 shows the possible diameter of the contact heads of the pressure sensors 36a, 36b, i.e., 10 mm, which also provides an indication regarding the size or diameter of the pressure pods 150a, 150b of the disposable cassette 130. The fresh or used dialysate pressure P further displaces (or attempts to displace) the cassette sheet 136, thereby increasing or decreasing the backflow force Fr acting on the pressure sensors 36a, 36b relative to the baseline or preload force Fp. The force difference between Fr and Fp caused by the positive or negative fluid pressure P is related to the actual fluid pressure value by the control unit 50, which is used for the pressure control described herein, which can be displayed by the user interface 58 and / or stored for distribution to a remote server computer for evaluation.

[0221] The pre-tensioning of the cassette sheet 136 by the pressure sensors 36a, 36b results in a pressure sensing area with high sensitivity and resolution, but it may tend to be sensitive to temperature. Therefore, it is conceivable to program the control unit 50 to compensate for the pressure readings of temperature. Here, the voltage output (or it may be a current output) from the pressure sensors 36a, 36b is corrected by adding an offset component, and the offset component is multiplied by an empirically determined temperature scaling coefficient to form a compensated voltage output (for example, using the temperature sensor 38 and the temperature sensing area 148 described above) as a function of the measured temperature, and the compensated voltage output is converted to a compensated positive or negative pressure, or is related to each other. A suitable scaling or offset algorithm stored in the control unit 50 is as follows: V T = V0 + gT, where V0 is the output from the pressure sensors 36a, 36b, V T is the corrected pressure output to be used by the control unit 50 in the future, g is the temperature scaling coefficient, T is the detected temperature.

[0222] FIG. 12 shows a plot used to determine the temperature scaling coefficient g for the scaling or offset algorithm described above. For each of the four plot lines, the baseline or preload Fp of the pressure sensors 36a, 36b was observed during a 30-minute fluid residence period for a fluid maintained at different temperatures (typical dialysate temperatures) in the range of 15°C to 40°C. As shown in FIG. 12, an equation characterizing each line was determined. Each equation takes the form y = mx + b, where (i) y is the above V T here, (ii) b is the above V0, (iii) x is the above measured temperature T, and (iv) m is the above scaling coefficient g. The m values from each trial were averaged to form the scaling coefficient g used in the scaling or offset algorithm stored in the control unit 50.

[0223] In an embodiment, the control unit 50 is configured to update a compensation algorithm for adjustment at the measured temperature T each time the output from the pressure sensor is read by the control unit or periodically. The control unit 50 uses the modified output V from the pressure sensors 36a, 36b for at least one of (a) controlling the medical fluid pump actuator to pump within the positive or negative pressure limits of the patient, (b) determining a line occlusion state, and / or (c) determining an empty state of a fresh or used dialysate container during or after a treatment. T is configured to be used.

[0224] As described above, the pre-tensioning of the cassette sheet 136 via the pressure sensors 36a, 36b results in a pressure sensing regime with high sensitivity and resolution, but may also be prone to mechanical creep sensitivity. To counter creep sensitivity, in one embodiment, the control unit 50 is programmed to pre-condition the cassette sheet 136 prior to treatment, e.g., during setup, whereby much of the variation in the pressure signal due to creep is eliminated before the measurements from the pressure sensors 36a, 36b become significant. To do so, after the disposable cassette 130 has been primed for treatment, the control unit 50 closes all pinch valves (34a through 34e), then actuates the peristaltic pump actuator 60 to pressurize the interior of the cassette 130 including the sheets of the pressure pods 150a, 150b to stretch the cassette sheet. The control unit 50 may be programmed to cyclically vibrate the cassette fluid pressure up and down a plurality of times, possibly in different directions, over a specified period of time to the pump actuator 60. The high pressure can be, for example, from 100% to 150% of the maximum operating pressure set for treatment, and the maximum operating pressure can be higher than the patient's pressure limit. For example, the pressure used during the priming or drain purge described above can be higher, e.g., 0.50 bar (7.25 psig) or more. The pre-conditioning of the cassette sheet 136 helps to make the uncompensated pressure readings more accurate, while temperature compensation helps to make the final pressure readings more accurate.

[0225] (Load cell calibration) Referring now to FIG. 13, in one embodiment, the system 10 and cycler 20 of the present disclosure use a scale 100 that includes a plurality of load cells (102a-102d) to monitor the amount of fresh dialysate delivered to a patient and the amount of used dialysate removed from the patient, and to enable the control unit 50 to calculate the amount of ultrafiltration ("UF") removed from the patient. The scale and load cells are advantageous for several reasons. First, the scale 100 is relatively accurate compared to other volume measurement techniques. Second, the pump actuator 60 can be a relatively simple peristaltic pump actuator, and the disposable portion of the pump can be a simple peristaltic pump tube 126, so the scale 100 reduces pump costs.

[0226] One drawback of the use of load cells is calibration. Load cells can be inaccurately read over time and thus need to be recalibrated. The present cycler 20 and related system 10 provide a weighing scale 100 having a plurality of load cells (102a - 102d), and an on - board structure 110 and related methodology for calibrating the weighing scale 100. In one embodiment, the weighing scale 100 includes a weight plate 104 disposed on top of the cycler 20 that supports the bag shelf enclosure 40 and the weights of each of the solution and drain containers (124a - 124d) and the associated fresh and used dialysate. The weight plate 104 and each of the weighed objects on the weight plate are supported by a plurality, e.g., four, load cells (102a - 102d) that collectively measure the total mass (bag shelf enclosure 40, containers (124a - 124d), and fluid) disposed on the weight plate. The on - board calibration structure 110 in one embodiment includes a linear actuator 112 (which can be of the same type used for pinch valves and can include, for example, a motor and lead screw, or a linear stepper motor), and a fifth or calibration load cell 114 disposed below the linear actuator 112, and the linear actuator 112 includes an actuating output shaft 116 fixed to the weight plate 104. The actuating output shaft 116 can extend through a hole formed in the weight plate 104, for example, and can be capped above the upper surface of the weight plate so as to be able to apply a downward force to the plate. Alternatively, the actuating output shaft 116 can be bolted to the underside of the weight plate 104, or slide into a groove formed in the underside of the weight plate 104, or be screwed into the underside of the weight plate 104, or include a flange having some alternative mechanical connection to the weight plate 104.

[0227] In one embodiment, the linear actuator 112 is actuated to apply a force that pulls the weight plate 104 or a downward force. In one implementation, the force is applied to the center of mass CM of the weight plate 104 as shown in FIG. 13. The operational load cells (102a - 102d) in the embodiment are each at least substantially equidistant from the center of mass CM and are spread apart from each other at equal x - coordinate distances (e.g., the distance between the contacts of load cells 102a and 102b is the same as the distance between the contacts of load cells 102d and 102c) and equal y - coordinate distances (e.g., the distance between the contacts of load cells 102a and 102d is the same as the distance between the contacts of load cells 102b and 102c).

[0228] An additional calibration load cell 114 measures the total pulling or downward force applied by the linear actuator 112, and the four operational load cells (102a - 102d) each measure a part or a quarter of the total force. If each of the operational load cells (102a - 102d) is operating properly, the sum of their outputs must equal the total force measured by the calibration load cell 114. In one example, assume a pulling force of 1000 Newtons (「N」) is applied by the linear actuator 112. The calibration load cell 114 should output 1000 N, while the operational load cells (102a - 102d) should each read 250 N and sum to 1000 N.

[0229] Since the calibration load cell 114 is not used very often, a calibration algorithm is applied assuming that the output of the calibration load cell 114 is more accurate than the collective output of the operational load cells (102a to 102d) used throughout each procedure. Thus, during calibration, if there is a discrepancy between what the calibration load cell 114 reads and the collective output of the operational load cells (102a to 102d), the control unit 50 that uses the calibration algorithm scales or offsets the collective output of the operational load cells (102a to 102d) to match the collective output of the calibration load cell 114. In the above example, assume that the operational load cells (102a to 102d) collectively read 995 N instead of 1000 N. Thus, the operational load cells (102a to 102d) are reading 0.5% low. Thereby, the control unit 50 of the cycler 20 is configured to correct the collective output of the operational load cells (102a to 102d) by a calibration factor of 1000 / 995 or 1.005 during the procedure.

[0230] The load cell calibration routine or algorithm of system 10 is executed at some desired criterion, for example, before the start of each procedure. The control unit 50 uses, for example, the offset output pressure from the operating load cells (102a to 102d) to control the duration of the operation of the pump actuator 60 (filling or draining of the patient). The control unit 50 is configured not to supply force to the linear actuator 112 during such an operation duration. The control unit 50 in another example is configured to determine the mass or volumetric flow rate during the procedure using two or more offset outputs from the operating load cells (102a to 102d). In a further example, the control unit 50 is configured to determine the amount of fresh dialysate delivered using at least two offset outputs from the operating load cells (102a to 102d). In yet another example, the control unit 50 is configured to determine the amount of used dialysate delivered using at least two offset outputs from the operating load cells (102a to 102d). In still another example, the control unit 50 is configured to determine the amount of used dialysate delivered to or removed from the patient using at least two offset outputs from the operating load cells (102a to 102d).

[0231] Since many of the weight values monitored and collected during the procedure are weight differences, it should also be understood that assuming the error does not change over the course of the procedure, the errors in the combined output of the operational load cells (102a through 102d) tend to cancel each other out. For example, the mass associated with a patient fill volume of, for example, 2 liters is monitored and controlled by the combined output of the operational load cells (102a through 102d) by recording the decrease in mass over the course of patient filling. The volume and mass associated with patient drain can be pre-set in the control unit 50 and, for example, a coefficient such as 1.3 can be multiplied by the fill volume to account for patient UF removed within the drain volume. The volume and mass associated with patient drain can alternatively be left open-ended and instead be controlled by detecting an increase in negative pressure characteristics by the pressure delivery sensing pod 150b and associated pressure sensor 36b, which indicates that the patient is essentially completely drained and that further drain may be uncomfortable for the patient. In either case, the operational load cells (102a through 102d) detect an increase in weight over the course of patient drain that should tend to cancel out the error of the operational load cells.

[0232] It should be understood that various modifications and changes to the presently preferred embodiments described herein will be apparent to those skilled in the art. Accordingly, such modifications and changes are intended to be covered by the appended claims. For example, although system 10 discloses peristaltic pumping, membrane pumping or volume pumping may alternatively be used. Although system 10 discloses in-line heating, batch heating may alternatively be used. Further, although calibrated load sensing is disclosed in connection with the supply and drain containers, alternatively, calibrated load sensing may be used with a dialysate preparation unit that pumps into one or more weight containers disposed on a weight plate.

Claims

1. A medical fluid system (10), wherein the medical fluid system (10) comprises: A medical fluid pump actuator (60); A medical fluid conveyance set (120) having a flexible sheet (136); A temperature sensor (38) positioned and arranged to detect the temperature of the medical fluid flowing through the medical fluid conveyance set (120); Pressure sensors (36a, 36b) positioned and arranged to contact the flexible sheet (136) when the medical fluid conveyance set (120) is loaded for operation with the medical fluid pump actuator (60); A control unit (50); and The control unit (50) is configured to: (i) precondition the flexible sheet (136) for operation with the pressure sensors (36a, 36b) by causing the medical fluid pump actuator (60) to apply pressure to the flexible sheet (136); (ii) use the output from the temperature sensor (38) in a compensation algorithm that corrects the output from the pressure sensors (36a, 36b). The compensation algorithm is: VT = V0 + gT where V0 is the output from the pressure sensors (36a, 36b); VT is the corrected pressure output; g is a temperature scaling factor; and T is the detected temperature. Medical fluid system (10).

2. The medical fluid pump actuator (60) of claim 1, wherein the medical fluid pump actuator (60) is a peristaltic pump actuator.

3. The pressure sensors (36a, 36b) are arranged such that when the medical fluid delivery set (120) is loaded for operation with the medical fluid pump actuator (60), the flexible sheet (136) is placed under tension through contact with the pressure sensors (36a, 36b). The medical fluid system (10) according to claim 1.

4. The pressure sensors (36a, 36b) are operable with portions of the pressure pods (150a, 150b) of the flexible sheet (136). The medical fluid system (10) according to claim 1.

5. During (i), the applied pressure is a fluid pressure. The medical fluid system (10) according to claim 1.

6. During (i), the applied pressure is a periodic up-and-down pressure. The medical fluid system (10) according to claim 1.

7. During (i), the applied pressure is from 100% to 150% of the maximum operating pressure supplied during the procedure. The medical fluid system (10) according to claim 1.

8. Includes a plurality of valves (34a to 34e) operable with the medical fluid delivery set (120), and the control unit (50) causes the plurality of valves (34a to 34e) to be closed during (i). The medical fluid system (10) according to claim 1.

9. The control unit (50) is configured to update the compensation algorithm for temperature each time the output from the pressure sensors (36a, 36b) is read by the control unit (50) during (i), or (ii) periodically. The medical fluid system (10) according to claim 1.

10. The control unit (50) is configured to use the modified output from the pressure sensors (36a, 36b) in (ii) for at least one of (a) controlling the medical fluid pump actuator (60) to pump within the patient's pressure limit, (b) determining a line occlusion state, or (c) determining a container empty state. The medical fluid system (10) according to claim 1.

11. A medical fluid system (10), wherein the medical fluid system (10) comprises: A medical fluid pump actuator (60); A medical fluid delivery set (120) having a flexible sheet (136); Pressure sensors (36a, 36b) arranged such that when the medical fluid delivery set (120) is loaded for operation with the medical fluid pump actuator (60), the flexible sheet (136) is placed under tension through contact with the pressure sensors (36a, 36b); A plurality of valves (34a to 34e) operable with the medical fluid delivery set (120); A control unit (50); and the control unit (50) is configured to: (i) close the plurality of valves (34a to 34e); (ii) precondition the flexible sheet (136) for operation with the pressure sensors (36a, 36b) by causing the medical fluid pump actuator (60) to apply pressure to the flexible sheet (136) while the plurality of valves (34a to 34e) are closed; A medical fluid system (10).

12. The pressure applied during the preconditioning is a fluid pressure. The medical fluid system (10) according to claim 11.

13. The medical fluid system according to claim 11, wherein the pressure applied during the preconditioning is a periodic up-and-down pressure.

14. The medical fluid system (10) according to claim 11, wherein the pressure applied during the preconditioning is 100% to 150% of the maximum operating pressure supplied during the treatment.

15. A medical fluid system (10), comprising: a medical fluid pump actuator (60); a medical fluid conveyance set (120) having a flexible sheet (136); a temperature sensor (38) positioned and arranged to detect the temperature of the medical fluid flowing through the medical fluid conveyance set (120); pressure sensors (36a, 36b) arranged such that when the medical fluid conveyance set (120) is loaded for operation with the medical fluid pump actuator (60), the flexible sheet (136) is placed under tension through contact with the pressure sensors (36a, 36b); a control unit (50); and the control unit (50) is configured to use the output from the temperature sensor (38) in a compensation algorithm for modifying the output from the pressure sensors (36a, 36b), the compensation algorithm being VT = V0 + gT, where V0 is the output from the pressure sensors (36a, 36b), VT is the corrected pressure output, g is a temperature scaling factor, and T is the detected temperature, for the medical fluid system (10).

16. The control unit (50) of the medical fluid system (10) according to claim 15 is configured to update the compensation algorithm for temperature either (i) each time the output from the pressure sensors (36a, 36b) is read by the control unit (50), or (ii) periodically. **Claim 17** The control unit (50) of the medical fluid system (10) according to claim 15 is configured to use the corrected output from the pressure sensors (36a, 36b) for at least one of (i) controlling the medical fluid pump actuator (60) to pump within the patient's pressure limit, (ii) determining a line occlusion state, or (iii) determining a container empty state.

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