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

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

There are various types of peritoneal dialysis therapies, including continuous ambulatory peritoneal dialysis ("CAPD"), automated peritoneal dialysis ("APD"), tidal flow dialysis and continuous flow peritoneal dialysis ("CFPD"). CAPD is a manual dialysis treatment. Here, the patient manually connects an implanted catheter to a drain to allow used or spent dialysis fluid to drain from the peritoneal chamber. The patient then switches fluid communication so that the patient catheter communicates with a bag of fresh dialysis fluid to infuse the fresh dialysis fluid through the catheter and into the patient. The patient disconnects the catheter from the fresh dialysis fluid bag and allows the dialysis fluid to dwell within the peritoneal chamber, wherein the transfer of waste, toxins and excess water takes place. After a dwell period, the patient repeats the manual dialysis procedure, for example, four times per day. Manual peritoneal dialysis requires a significant amount of time and effort from the patient, leaving ample room for improvement.

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

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

Known APD systems include a machine or cycler that accepts and actuates a pumping cassette having a hard part and a soft part that is deformable for performing pumping and valving operations. Sealing the fluid disposable cassette with a pneumatic path via a gasket to provide actuation has proven to be a potential field issue, which can delay treatment start time and affect user experience. Pneumatic cassette systems also produce acoustic noise, which may be a source of customer dissatisfaction.

For each of the above reasons, an improved APD machine is needed.

<CIT> discloses a system and method to allow multiple patients to receive peritoneal dialysis treatment at a walk-in facility without having to keep fresh dialysis solution on hand themselves. The walk-in facility is enabled to receive a peritoneal dialysis prescription from a patient, verify the prescription, determine the appropriate treatment for the patient, provide the patient with the appropriate dialysis solution in the appropriate amount, and enable the patient to undergo a dialysis treatment at the facility. The walk-in facility can also be enabled to monitor the patient's home dialysis treatment and to adjust the patient's treatment at the facility accordingly. The facility can be enabled to produce dialysis solution on demand by manufacturing the solution from solution components according to a patient's prescription. Moreover, the facility can use a sorbent system to regenerate effluent dialysis solution into fresh dialysis solution.

The present disclosure sets forth a streamlined automated peritoneal dialysis ("APD") system and associated cycler that uses a peristaltic pump and disposable set that organizes tubing and performs many functions discussed below. The cycler of the system in one embodiment includes a peristaltic pump actuator that is capable of pumping in two directions. Flow in either direction advances through a disposable cassette, which is part of an overall disposable set.

The disposable cassette is mounted within a housing of the cycler and is in one embodiment mounted vertically against an actuation surface of the housing and then enclosed between the actuation surface and a hinged door of the housing. A user interface communicating with a control unit is provided next to the door of the housing so that the patient or user generally interacts with one surface of the machine for inputting commands and receiving data and for loading the disposable cassette.

The system in one embodiment also includes a bag shelf enclosure that serves multiple purposes. The bag shelf enclosure is sized such that when the cycler is not in use, the cycler may be stored inside of the enclosure. The bag shelf enclosure is also sized such that when the cycler is in use, the bag shelf enclosure may be set on the top of the cycler. The bag shelf holds multiple containers or bags, such as multiple supply containers and one or more drain container. In one example, multiple supply containers are located within the bag shelf enclosure during treatment, while a drain container and a last fill container are located outside of and on top of the enclosure. The bag shelf enclosure may include color-coded markers provided at locations for loading containers or bags having lines that extend into the cycler through apertures, wherein the apertures have like color-coded markers. The matching color-coded markers make it easy for the patient or caregiver to identify which bag and line belongs at which location on the bag shelf enclosure.

It is contemplated to use the supply containers or bags later as drain containers or bags to reduce overall disposable cost. For example, assume that the patient is full of effluent at the beginning of treatment. That effluent is initially drained from the patient and delivered to an empty drain container. A first patient fill is then delivered from a first supply container to the patient, and after a specified dwell period, delivered to the same drain container or to a different drain container depending on the sizes of the drain container(s). The drain container(s) is/are used to receive effluent until the first supply container is emptied after which the first supply container receives effluent after a dwell period using PD fluid provided from a second supply container. The first supply container is used to receive effluent, perhaps over multiple patient fills, dwells and drains, until the second supply container is empty. At that point the patient may receive a last fill of a different formulation of peritoneal dialysis fluid, which remains within the patient until the next night treatment or perhaps until a midday exchange.

At the end of treatment, multiple containers or bags are full of effluent. To prevent the patient or caregiver from having to transport the drain bags to a house drain, e.g., toilet, sink or bathtub, the control unit of the cycler is programed to prompt the user to remove the patient line from the patient's transfer set and carry the distal end of the patient line to the house drain. It should be appreciated that "house drain" as used herein means any type of drain provided in any type of building or domicile, such as a home, apartment, work building, hospital, clinic, public or private facility, etc. If needed, 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 a drain button on the user interface, upon which the cycler actuates the peristaltic pump actuator in a direction so as to pull used dialysis fluid or effluent from each of the drain containers (one or more of which may be former supply containers) and pump the used dialysis fluid through the patient line (and extension line if needed) to the house drain. The cycler detects when each drain container is empty (e.g., via a weigh scale and/or pressure sensor discussed in detail below) and automatically switches valve actuators, e.g., pinch valve actuators, to sequence between drain containers until each is emptied. The above sequence is repeated for any residual fresh dialysis fluid in a main supply or last fill container. It should be appreciated that multiple drain containers (one or more of which may be former supply containers) may be drained simultaneously or at the same time, e.g., to save time. In this manner, once the patient disconnects from the patient line and presses the drain button, the patient is free to begin their day.

As mentioned above, the cycler uses peristaltic pumping in one embodiment. A peristaltic pump actuator under control of the control unit is located on the actuation 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. In operation, the peristaltic pump actuator compresses the peristaltic pump tube at multiple points against a raceway. The operational proximity of the raceway to the peristaltic pump actuator would make the loading of the tube difficult. The present cycler accordingly includes a moveable raceway that translates out of the way of the peristaltic pump actuator via a linkage when the patient or caregiver opens the door of the cycler to load the cassette. After the cassette is loaded, the closing of the cycler door causes the moveable raceway to translate via the linkage into 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., linear stepper motor) is provided to automatically translate the raceway out of the way of the peristaltic pump actuator when the patient or caregiver opens the door of the cycler to load the cassette and to automatically translate the raceway into the operable position when the door is closed. In a further alternative embodiment, motor and lead screw assembly, or a linear actuator (e.g., linear stepper motor) is provided, but the patient or caregiver instead presses one or more button on the user interface to translate the raceway out of the way or into the operable position.

In an embodiment, the raceway is mounted to a block or member that is translatable across the actuation surface towards and away from the peristaltic pump actuator. Besides the translatable motion of the member (and the raceway), the moveable raceway is also able to rotate about a pivot provided at one end of the raceway, wherein the pivot is mounted to the translatable member. The other end of the raceway is spring-loaded via a spring, e.g., compression spring, confined between the raceway end and the member. The spring pushes the raceway about the pivot into a desirable operating position around the peristaltic pumping tube when the member has been translated towards the peristaltic pump actuator. The pivoting raceway absorbs or allows for variances due to tubing tolerance and may also provide a dampening effect that aids noise reduction.

As mentioned above, the cycler uses pinch valve actuators in one embodiment, wherein the disposable cassette is provided with valve seats that receive the pinch valve actuators to occlude or close a fluid pathway provided by the disposable cassette. Here, the cassette is sealed to and covered by a flexible sheet, e.g., flexible plastic, that the pinch valve actuators press into respective valve seats to close a respective fluid pathway. The pinch valve actuators retract to open their respective fluid pathways.

The pinch valves are each driven by a linear actuator, which may be any suitable type of linear actuator, such as a linear stepper motor, which provides a necessary amount of travel (e.g., up to <NUM>) and a needed amount of pressurized cassette sheeting closing force (e.g., <NUM> to <NUM> Newtons ("N") or less). The linear actuator drives a valve plunger back and forth to press the cassette sheeting against, and allow the sheeting 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 is slidingly coupled to the proximal end effector. A spring, such as a wave or compression spring, may be provided with the plunger and positioned so as to bias the distal end effector outwardly relative to the proximal end effector. The variable distance provided by the spring enables the pinch valve to contact the cassette sheeting initially at a lesser closing force, which increases steadily as the spring is compressed. In an embodiment, a flexible membrane, such as a silicone membrane, is fixed to the actuation surface so as to cover the end of distal end effector, such that the flexible membrane contacts the cassette sheeting. When the spring is fully compressed, the cassette sheeting sees the full force of the linear actuator and the spring. The spring accordingly provides a force buffer that helps to protect the flexible membrane over multiple treatments and the cassette sheeting over the course of a single treatment. The spring may also help with variances due to tolerance in the disposable cassette and the loading of the cassette, and may further allow for a smaller or less expensive linear actuator.

As mentioned, the disposable cassette provides multiple valves seats, which may include a patient line valve seat, first and second supply line valve seats, a last fill line valve seat and a drain line valve seat. In one embodiment, the patient line valve seat is separated fluidically from a first peristaltic tube port by an inline fluid heating pathway, e.g., a serpentine pathway. When the disposable cassette is mounted for operation, the inline fluid heating pathway is abutted against a heater, such as a resistive plate heater.

In one embodiment, the first and second supply line valve seats, a last fill line valve seat and a drain line valve seat are each located within a common well, which is in fluid communication with a second peristaltic tube port. In this manner, fresh dialysis fluid may be pumped from any of the supply containers 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 the inline fluid heating pathway, where the fresh dialysis fluid is heated, and then pumped out the patient line valve seat to the patient. Used dialysis fluid or effluent may be pumped from the patient in a second direction through the patient line valve seat and the inline fluid heating pathway, where the used dialysis fluid is not heated, into the common well and out the drain line valve seat to a drain container.

Any of the valve seats described herein may include a tapered sealing surface surrounded by a plurality of displacement ribs, each extending from a rigid wall of the disposable cassette, wherein at least some of the displacement ribs are spaced apart to prevent or mitigate against an unwanted occlusion of the tapered sealing surface by the flexible sheet, and to allow fresh or used dialysis flow therethrough. The displacement ribs may be completely separate from each other or extend from a common cylindrical base. The displacement ribs may be separate from the tapered sealing surface or extend from an outer edge of the tapered sealing surface. The displacement ribs prevent ingress of the flexible sheet into the tapered sealing surface. The displacement ribs may also guide the respective pinch valve plunger towards a center of the valve seat, while also providing an amount of give or play between the pinch valve plunger and the valve seat. The tapered sealing surface in an embodiment 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. In an embodiment, the opening extends through a port located on the other side of a rigid body of the disposable cassette, wherein the port sealingly accepts (attaches to) a tube or line, such as a patient line, supply line or drain line. The tapered sealing surface may also include or define one or more circular sealing ring that presses into the flexible sheet when the flexible sheet is closed by the pinch valve.

In an embodiment, a first or patient pressure sensing pod is located in the disposable cassette directly adjacent to the patient line valve seat. The patient pressure sensing pod when the disposable cassette is loaded is abutted against a first or patient pressure sensor, which outputs to the cycler control unit. The patient pressure sensor output may be used to control positive and negative pumping pressures experienced by the patient to be within safe pressure limits. A second or pumping pressure sensing pod is located in the disposable cassette between the common well and the second peristaltic tube port. The pumping pressure sensing pod when the disposable cassette is loaded is abutted against a second or pumping pressure sensor, which outputs to the cycler control unit. The pumping pressure sensor output may be used to detect supply and drain line occlusions and/or supply empty conditions.

The disposable cassette may also include one or more area, which when loaded for operation abuts against a thermocouple or other temperature sensor outputting to the control unit. A temperature sensing area may for example be placed at the end of the inline fluid heating pathway directly adjacent to the patient pressure sensing pod, so that the outlet temperature of the fresh dialysis fluid to the patient may be monitored and controlled to a desired temperature, e.g., body temperature or <NUM> and e.g., via a proportional, integral, derivative ("PID") routine performed by the control unit using feedback from the temperature sensor. A second temperature sensor may located so as to detect a temperature at the inlet of the inline fluid heating pathway if needed, which may likewise provide useful information for the PID routine.

It is contemplated to mount the pressure sensors in the actuation surface of the cycler such that when the disposable cassette is loaded for operation, the cassette sheeting, which may be polyvinyl chloride ("PVC"), is contacted and placed under tension by the pressure sensor, creating a baseline force measured by the pressure sensor. Fresh or used dialysis fluid pressure displaces (or attempts to displace) the cassette sheeting further and thereby increases or decreases the fluid force acting on the pressure sensor relative to the baseline force. The force differences caused by positive or negative fluid pressure are correlated to actual fluid pressure values by the control unit, which are used for pressure control and which may be displayed by the user interface and/or stored for delivery to a remote computer for evaluation.

The pre-tensioning of the cassette sheeting by the pressure sensor results in a pressure sensing regime having high sensitivity and resolution, but which may be prone to temperature sensitivity. It is accordingly contemplated to compensate for temperature. Here, a voltage output (or current output) from the pressure sensor is modified by adding a component, which is a function of a measured temperature (e.g., using the thermocouple discussed above) multiplied by an empirically determined temperature scaling coefficient, to form a compensated voltage output, which is then converted or correlated to a compensated positive or negative pressure.

As mentioned above, the pre-tensioning of the cassette sheeting by the pressure sensor results in a pressure sensing regime having high sensitivity and resolution, but which may also be prone to mechanical creep sensitivity. To combat creep sensitivity, the control unit is programmed in one embodiment to precondition the cassette sheeting prior to treatment, e.g., during setup, so that much of the variance to the pressure signal due to creep is eliminated before the pressure measurements matter. To do so, the control unit after the disposable cassette is primed causes all pinch valves to close and then actuates the peristaltic pump actuator so as to pressurize the inside of the cassette, including the pressure pods, to stretch the cassette sheeting. The control unit may be programmed to cause the pump actuator to oscillate the cassette fluid pressure up and down cyclically multiple times over a specified duration, wherein the upper pressure may be, for example, from <NUM>% to <NUM>% of a maximum operational pressure set for treatment. The preconditioning of the cassette sheeting helps to make the uncompensated pressure reading more accurate, while the temperature compensation helps to make the final pressure reading more accurate.

The system and cycler of the present disclosure in one embodiment employ a weigh scale having multiple load cells to monitor the amount of fresh dialysis fluid delivered to the patient, the amount of used dialysis fluid removed from the patient, and from there enable the control unit to calculate an amount of ultrafiltration ("UF") removed from the patient. Weigh scales and load cells are advantageous for a number of reasons. First, weigh scales are relatively accurate compared with other volumetric measurement techniques. Second, the weigh scale reduces the pump cost because the pump actuator may be a relatively simple peristaltic pump actuator and the disposable portion of the pump may be a simple peristaltic pump tube.

One drawback of the use of load cells is calibration. Load cells may over time read inaccurately and therefore need to be recalibrated. The present cycler and associated system provide a weigh scale having multiple load cells and an onboard structure and methodology for calibrating the weigh scale. In one embodiment, the weigh scale includes a weigh plate located at the top of the cycler, which supports the weight of the bag shelf enclosure and each of the solution and drain containers and associated fresh and used dialysis fluid. The weigh plate and each of the weighted items on the weigh plate are supported by multiple, e.g., four, load cells that collectively measure the total mass placed on the weigh plate (bag shelf enclosure, containers and fluids). The onboard calibration structure in one embodiment includes a fifth load cell and a linear actuator (may be of the same type as used for the pinch valves) located between the fifth load cell and the weigh plate.

The linear actuator includes an actuation output shaft that is fixed to the weigh plate such that the linear actuator can apply a pulling or downward force to the weigh plate. In one implementation, the pulling force is applied to the center of mass of the underside of the weigh plate. The additional calibration load cell measures the total force applied, while the four operational load cells each measure a fraction or fourth of the total force. If the operational load cells are each performing properly, the sum of their outputs should equal the total force measured by the calibration load cell. In an example, suppose <NUM> Newtons ("N") of pulling force is applied by the linear actuator. The calibration load cell should thereafter output <NUM> N, while the equidistant operational load cells 102a to 102d should each read <NUM> N, totaling <NUM> N in combination.

Because the calibration load cell is used infrequently, the calibration algorithm is applied assuming that the output of calibration load cell is more accurate than the collective outputs of the operational load cells, which are used throughout each treatment. So if during calibration there is a mismatch between what the calibration load cell reads versus 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 that of the calibration load cell. In the above example, suppose the operational load cells actually collectively read <NUM> N instead of <NUM> N. The operational load cells are accordingly reading low by <NUM>%. The control unit is thereby configured during treatment to modify the collective output of the operational load cells by a calibration factor of <NUM>/<NUM> or <NUM>.

Because the calibration load cell is used infrequently, the calibration algorithm assumes that its output is more accurate than the collective output of the operational load cells, which are used throughout each treatment. So if during calibration there is a mismatch between what the calibration load cell reads versus 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 that of the calibration load cell. In the above example, suppose the operational load cells actually collectively read <NUM> Newtons instead of <NUM> Newtons. The operational load cells therefore only sense <NUM> Newtons of the applied <NUM> Newtons. The operational load cells are accordingly reading low by <NUM>%. The control unit of the cycler is thereby configured during treatment to modify the collective output of the operational sensors by a calibration factor of <NUM>/<NUM> or <NUM>.

The load cell calibration routine or algorithm is performed on some desired basis, e.g., before the start of each treatment. It should also be appreciated that because many of the weight values monitored and collected during treatment are weight differences, error in the collective output of the operational load cells tends to cancel itself out, assuming that the error does not change over the course of treatment. For example, the mass associated with a patient fill volume of two liters is monitored and controlled by the collective output of the operational load cells recording a drop in mass over the course of the patient fill. The volume and mass associated with a patient drain may be preset in the control unit, e.g., be a factor, such as <NUM>, multiplied by the fill volume to account for patient UF removed into the drain volume. The volume and mass associated with a patient drain may alternatively be left open-ended and be controlled instead by the sensing of a characteristic rise in negative pressure by the pumping pressure sensing pod and associated pressure sensor, indicating that the patient is essentially fully drained and that further draining may be uncomfortable for the patient. In either case, the operational load cells sense an increase in weight over the course of the patient drain, which should tend to cancel any error in the operational load cells.

According to the present invention, there is provided a peritoneal dialysis system that comprises a cycler including a pump actuator; a disposable set including a pumping portion operable with the pump actuator, a patient line positioned to fluidly communicate with the pumping portion, and a drain container positioned to fluidly communicate with the pumping portion; and a control unit configured to cause the pump actuator to actuate the pumping portion (i) to run a peritoneal dialysis treatment in which fresh dialysis fluid is pumped through the patient line to a patient and used dialysis fluid is pumped from the patient to the drain container, and (ii) at the end of the peritoneal dialysis treatment, to pump the used dialysis fluid from the drain container, through the patient line, to a house drain.

Embodiments of the peritoneal dialysis system of the present invention are described in the dependent claims. These embodiments may be used alone or in combination.

It is accordingly an advantage of the present disclosure to provide an accurate APD system that uses a relatively simple and cost effective peristaltic pump.

It is another advantage of the present disclosure to provide an APD system that eliminates certain sealing issues present in known APD systems.

It is a further advantage of the present disclosure to provide an APD pump driven system that eliminates bulky pneumatic equipment associated with certain APD systems.

It is yet another advantage of the present disclosure to provide an APD pump driven system that reduces noise relative to pneumatic systems.

It is yet a further advantage of the present disclosure to provide an APD system that manages peritoneal dialysis fluid flow so as to be within safe and comfortable patient pressure limits.

It is still another advantage of the present disclosure to provide an APD system having a simplified disposable set.

It is still a further advantage of the present disclosure to provide an APD system having accurate pressure and weight sensing.

Moreover, it is an advantage of the present disclosure to provide an APD system that simplifies used dialysis fluid removal to house drain for the patient.

Referring now to the drawings and in particular to <FIG>, an embodiment of system <NUM> includes an automated peritoneal dialysis ("APD") cycler <NUM> having a housing <NUM>, which uses peristaltic pumping in one embodiment, and which operates a disposable set <NUM>. All rigid and flexible tubing portions of disposable set <NUM> may be made of one or more plastic, e.g., polyvinylchloride ("PVC") or a non-PVC material, such as polyethylene ("PE"), polyurethane ("PU") or polycarbonate ("PC"). Housing <NUM> of cycler <NUM> may be made of any of the above plastics, and/or of metal, e.g., stainless steel, steel and/or aluminum.

In the illustrated embodiment, housing <NUM> is provided with hinged door <NUM> having a series of holes or slots 26a, 26b, 26c, 26d and 26e for tubing 122a to 122e, respectively, of disposable set <NUM> to extend from the inside of housing <NUM> to the outside of the housing. While illustrated as elongated slots, the apertures 26a to 26e may alternatively be holes. Slots 26a to 26e are advantageous however because they allow door <NUM> to be hinged open without placing tubing 122a to 122e under too much tension. In an embodiment, tubing 122a to 122e is preconnected and sterilized with a disposable pumping cassette illustrated below. The distal ends of tubing 122a to 122e are removed from sterilized caps at treatment setup and spiked to containers or bags 124a to 124d (line 122e is the patient line) of disposable set <NUM>. Container or bag 124a may be a drain container or bag. Containers or bags 124b and 124c may be primary fresh dialysis fluid supply containers or bags. Container 124d may be a last fill container or bag, which holds a different formulation of fresh dialysis fluid, e.g., two to three liters of icodextrin, which is formulated to remain inside the patient's peritoneal cavity after the patient disconnects from disposable set <NUM>.

In the illustrated embodiment, door <NUM> is vertically disposed and thus holds the disposable cassette of set <NUM> vertically within housing <NUM> of cycler <NUM> and against an actuation surface of the housing. Door <NUM> is located adjacent to a user interface portion of cycler <NUM>, which includes a control unit <NUM> having one or more processor <NUM>, one or more memory <NUM> and a video controller <NUM>, which interfaces one or more processor <NUM> and one or more memory <NUM> with a user interface <NUM>. User interface <NUM> may include a touch screen and/or electromechanical buttons, such as membrane switches for inputting user commands and providing instructions, alerts and alarms. Providing user interface <NUM> next to door <NUM> of housing <NUM> enables the patient or other user to generally interact with one surface of machine <NUM> for inputting commands, receiving data and loading/unloading the disposable cassette. User interface <NUM> may alternatively or additionally be a remote user interface, e.g., via a tablet or smartphone. Control unit <NUM> may also include a transceiver and a wired or wireless connection to a network (not illustrated), e.g., the internet, for sending treatment data to and receiving prescription instructions/changes from a doctor's or clinician's server interfacing with a doctor's or clinician's computer. The data sent to the doctor's or clinician's computer may be analyzed and/or converted to, or used to form, other data useful for analysis. Such data conversion is performed alternatively or additionally at control unit <NUM> of cycler <NUM>.

<FIG> illustrates that system <NUM> in one embodiment also includes a bag shelf enclosure <NUM> that serves multiple purposes. Bag shelf enclosure <NUM> is sized such that when cycler <NUM> is not in use, the cycler may be stored inside of the enclosure. In the illustrated embodiment, bag shelf enclosure <NUM> includes a rotatably hinged handle <NUM> that enables the user to transport the enclosure with cycler <NUM> stored therein. As illustrated in <FIG>, bag shelf enclosure <NUM> is also sized such that when cycler <NUM> is in use, the bag shelf enclosure may be set on the top of the cycler (on top of a weigh plate in one embodiment as discussed in detail below). Bag shelf holds multiple containers or bags 124a to 124d, such as multiple supply containers 124b to 124d and one or more drain container 124a. As illustrated, the containers or bags are held within enclosure <NUM> and on the outer, upper surface of the enclosure.

Bag shelf enclosure <NUM> may include color-coded markers 44a to 44d provided at locations for loading containers or bags having lines that extend into cycler <NUM> through slots or apertures, 26a to 26d, wherein the slots or apertures have like color-coded markers or borders. The matching color-coded markers 44a to 44d and slot borders make it easy for the patient or caregiver to identify which bag and line belongs at which location on bag shelf enclosure <NUM>. For instance, marker 44a and the border of slot 26a may be green to signify drain line 122a and drain container 124a and the desired location for the drain container. Markers 44b and 44c and the borders of slots 26b and 26c may be blue to signify primary supply lines 122b, 122c and supply containers 124b, 124c and the desired locations of the supply containers. Marker 44d and the border of slot 26d may be red to signify last fill line 122d and last fill container 124d and the desired location for the last fill container.

It is contemplated to use the supply containers or bags, e.g., the primary supply containers or bags 124b and 124c later as drain containers or bags to reduce overall disposable cost. For example, assume that the patient is full of effluent at the beginning of treatment. That effluent is initially drained from the patient and delivered to initially empty drain container 124a. A first patient fill is then delivered from a first primary supply container 124b to the patient, and after a specified dwell period delivered to the same drain container 124a (or perhaps to a different drain container depending on the sizes of the drain container(s)). In an embodiment, drain container 124a and primary supply containers 124b and 124c are larger, six liter, containers for holding multiple cycles' worth of fresh and used dialysis fluid. Drain container(s) 124a is/are used to receive effluent until first supply container 124b is emptied after which the first supply container receives effluent after a dwell period using PD fluid provided from second supply container 124c. First supply container 124b is used to receive patient effluent, perhaps over multiple patient fills, dwells and drains, until second supply container 124c is empty. At that point the patient may receive a last fill of a different formulation of peritoneal dialysis fluid from last fill container 124d, which remains within the patient until the next night treatment or perhaps until a midday exchange. If second supply container 124c is empty at the end of treatment, it may be used as the initial empty drain container at the start of the next treatment, further reducing disposable waste and cost.

In an example, containers 124a to 124d may be used as follows where the patient is initially full:.

In an example, containers 124a to 124d may be used as follows where the patient is initially empty:.

At the end of treatment, multiple containers or bags (e.g., containers 124a, 124b) are full of effluent. Also, a remaining supply container 124c may contain residual fresh dialysis fluid. To prevent the patient or caregiver from having to transport the full drain bags to a house drain, e.g., toilet, sink or bathtub, control unit <NUM> of cycler <NUM> is programed to prompt the user to remove patient line 122e from the patient's transfer set and carry the distal end of patient line 122e to the house drain. If needed, a reusable extension line 122f may be connected to the distal end of patient line 122e to reach the house drain. The patient or caregiver then presses a drain button on user interface <NUM>, upon which cycler <NUM> actuates the pump actuator, e.g., peristaltic pump actuator, in a direction so as to pull used dialysis fluid or effluent from each of the drain containers 124a, 124b (one or more of which may be former supply containers) and pump the used dialysis fluid through patient line 122e (and extension line 122f if needed) to the house drain. Residual fresh dialysis fluid is removed from supply container 124c in the same way. The drain button in an embodiment is only displayed at the end of treatment, e.g., via a touch screen display, when the button is needed. The drain button may alternatively be a membrane switch that is only enabled at the end of treatment when the button is needed. Additionally, regardless of its type, the drain button may only be displayed and/or enabled after the patient presses a confirm button provide by user interface <NUM> in response to a prompt by the user interface for the patient or caregiver to confirm that patient line 122e/122f has been run to the house drain.

Control unit <NUM> of cycler <NUM> detects when each drain container 124a, 124b is empty (e.g., via a weigh scale and/or pressure sensor operating with a pressure pod of the disposable cassette as discussed in detail below) and automatically switches valve actuators, e.g., pinch valve actuators, to sequence between drain containers 124a, 124b (and supply container 124c if needed) until each is emptied. In particular, cycler <NUM> includes a patient valve actuator that operates with a patient valve seat provided by disposable set <NUM>, and a drain valve actuator that operates with a drain valve seat provided by the disposable set, and wherein control unit <NUM> 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 to pump the used dialysis fluid from the drain container, through the patient line, to the house drain. It should be appreciated that multiple drain containers (one or more of which may be former supply containers) may be drained simultaneously, over the same duration or overlapping durations, e.g., to save time.

It is also contemplated for control unit <NUM> to look for leftover fresh dialysis fluid in any remaining supply container, e.g., containers 124c and 124d, and to cause the pump actuator to pump the leftover fresh dialysis fluid to house drain via the patient line. In this manner, once the patient disconnects from patient line 122e and presses the drain button, the patient can assume that all fresh and used dialysis fluid is being pumped to house drain and is thus free to begin his or her day.

It should be appreciated that while system <NUM> is described in this section as pumping effluent or leftover fresh dialysis fluid to a house drain, control unit <NUM> may in an alternative embodiment pump any remaining fluid (fresh or used) from any container 124a to 124d to any other container 124a to 124d. In an embodiment, after treatment when the patient disconnects from patient line 122e, the patient places the distal end of the patient line in a priming holder (not illustrated) located on the housing <NUM> of cycler <NUM> and confirms this action at user interface <NUM>. The distal end of patient line 122e is left open to atmosphere. Control unit <NUM> then runs a sequence in which all fluid currently residing in patient line 122e is pumped to a desired destination container 124a to 124d so that patient line 122e is completely or almost completely filled with air. Control unit <NUM> then causes whatever dialysis fluid (fresh or used) is to be moved from whatever container 124a to 124d to be pumped via peristaltic pump actuator <NUM>, rotating in a patient fill direction for a known number of strokes, to push an amount of the fluid through inline fluid heating pathway <NUM> and into a safe portion of patient line 122e, so that the fluid does not spill out the end of the patient line. Control unit <NUM> then reverses the direction of peristaltic pump actuator <NUM> so as to rotate in a patient drain direction, for a known number of strokes, and changes the valve states of the relevant valve actuators, to push that amount of the fluid through the safe portion of patient line 122e and inline fluid heating pathway <NUM> to a desired destination container 124a to 124d. Control unit <NUM> then repeats the pumping and reverse pumping actions until a desired amount of fresh or used dialysis fluid is moved from a desired source container 124a to 124d to a desired destination container 124a to 124d.

Referring now to <FIG>, one embodiment for actuation surface <NUM> of cycler <NUM> is illustrated. Actuation surface <NUM> in <FIG> is hidden behind door <NUM>. When door <NUM> is opened, actuation surface <NUM> as illustrated in <FIG> is exposed. Labels "top", "bottom", "user interface" and "patient end" are provided in <FIG> to illustrate how actuation surface <NUM> is oriented in <FIG>. Actuation surface <NUM> in the illustrated embodiment includes a heater <NUM>, such as a resistive plate that heats an inline fluid heating pathway provided by the disposable cassette illustrated below. Actuation surface <NUM> also includes a plurality of valve actuators 34a to 34e, including a drain line valve actuator 34a, main supply line valve actuators 34b and 34c, last fill line valve actuator 34d and patient line valve actuator 34e. An embodiment for valve actuators 34a to 34e is illustrated in detail below. Actuation surface <NUM> also includes a plurality of pressure sensors, including a patient pressure sensor 36a and a pumping pressure sensor 36b. An embodiment for pressure sensors 36a and 36b is likewise illustrated in detail below. At least one temperature sensor <NUM>, e.g., thermocouple or thermistor, is also provided. Control unit <NUM> shown figuratively in <FIG> controls heater <NUM> and valve actuators 34a to 34e and receives inputs from pressure sensors 36a, 36b and temperature sensor <NUM>.

<FIG> further illustrates that a peristaltic pump actuator <NUM> under control of control unit <NUM> is located on and extends behind actuation surface <NUM> of cycler <NUM>. Pump actuator <NUM> may include a pump head <NUM> located on actuation surface <NUM> and a driver or motor <NUM> located behind actuation surface <NUM>. The disposable cassette includes a peristaltic pump tube that the user guides over pump head <NUM> of peristaltic pump actuator <NUM> when loading the cassette. In operation, peristaltic pump actuator <NUM> compresses the peristaltic pump tube at multiple points against a raceway <NUM>. The operational proximity of raceway <NUM> to peristaltic pump actuator <NUM> would make the loading of the tube difficult. The present cycler <NUM> accordingly provides a moveable raceway <NUM> that translates out of the way of the peristaltic pump actuator, for example, via a linkage (not illustrated) when the patient or caregiver opens door <NUM> of cycler <NUM> to load the disposable cassette. After the cassette is loaded, the closing of cycler door <NUM> causes moveable raceway <NUM> to translate, for example, via the linkage into 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., linear stepper motor, not illustrated) is provided to automatically translate raceway <NUM> out of the way of peristaltic pump actuator <NUM> when the patient or caregiver opens door <NUM> to load the cassette and to automatically translate raceway <NUM> into an operable position when door <NUM> is closed. In a further alternative embodiment, motor and lead screw assembly, or a linear actuator (e.g., linear stepper motor, not illustrated) is provided, but the patient or caregiver instead presses one or more button on the user interface <NUM> to translate raceway <NUM> out of the way or into the operable position.

In an embodiment, raceway <NUM> is mounted to a block or member <NUM> that is translatable across actuation surface <NUM> towards and away from peristaltic pump actuator <NUM>. Besides the translatable motion of member <NUM> (and raceway <NUM>), moveable raceway <NUM> is also able to rotate about a pivot <NUM> provided at one end 66a of raceway <NUM>, wherein pivot <NUM> is mounted to translatable member <NUM>. The other end 66b of raceway <NUM> is spring-loaded via a spring <NUM>, e.g., compression spring, confined between raceway end 66b and member <NUM>. In the illustrated embodiment, spring <NUM> is inserted over a threaded bolt <NUM> that extends through raceway end 66b and threads into member <NUM>. Threaded bolt <NUM> incudes a head <NUM> that sets and end of spring travel for raceway <NUM>, wherein the end of travel may be adjusted in or out by turning threaded bolt <NUM> clockwise or counterclockwise, respectively. In the illustrated embodiment, spring <NUM> pushes raceway <NUM> about pivot <NUM> and into a desirable operating position around the peristaltic pumping tube after member <NUM> has been translated towards peristaltic pump actuator <NUM>. Pivoting raceway <NUM> absorbs or allows for variances due to tubing tolerance and may also provide a dampening effect that aids noise reduction.

<FIG> and <FIG> illustrate that member <NUM> and raceway <NUM> slide along a linear rail <NUM> formed or provided along actuation surface <NUM>. Member <NUM> on its underside includes a rail receiver (not viewable) sized to fit and operate with the linear rail <NUM>. The rail receiver in an embodiment interacts with linear rail <NUM>, e.g., via a tongue and groove fit, such that linear rail <NUM> holds member <NUM> and raceway <NUM> slidingly engaged along actuation surface <NUM>. Additionally or alternatively, <FIG> illustrates that elongated slots <NUM> may be formed in member <NUM>, which receive bolts that may be loosely tightened such that member <NUM> and raceway <NUM> may slide along actuation surface <NUM> while still being held to the surface.

Section IIIA of <FIG> illustrates peristaltic pumping tube <NUM> of disposable set <NUM> as it is about to be loaded. Member <NUM> and raceway <NUM> are in a fully retracted or out of the way position. Section IIIB of <FIG> illustrates that peristaltic pumping tube <NUM> has been stretched or placed into operable position about pump head <NUM> of peristaltic pump actuator <NUM>. Member <NUM> and raceway <NUM> are again in a fully retracted or out of the way position. Section IIIC of <FIG> illustrates that member <NUM> and raceway <NUM> have been translated into an operable position relative to peristaltic pumping tube <NUM> and pump head <NUM> of peristaltic pump actuator <NUM>.

As mentioned above, a purely mechanical linkage (not illustrated) may be provided that pulls member <NUM> and raceway <NUM> into the fully retracted or out of the way position of sections IIIA and IIIB of <FIG>, e.g., wherein the linkage is actuated via the opening of door <NUM>. The linkage pushes member <NUM> and raceway <NUM> into the operable position of section IIIC of <FIG>, e.g., wherein the linkage is actuated via the closing of door <NUM>. Alternatively a motorized mechanism, such as a linear actuator or motor and lead screw, are provided to automatically (i) pull member <NUM> and raceway <NUM> into the fully retracted or out of the way position of sections IIIA and IIIB of <FIG> when door <NUM> is opened and (ii) push member <NUM> and raceway <NUM> into the operable position of section IIIC of <FIG> when door <NUM> is closed. Further alternatively, if it is desirable to be able to access actuation surface <NUM> when member <NUM> and raceway <NUM> are in the operable position, a button may be provided on user interface <NUM> to actuate the motorized mechanism, e.g., to both retract and extend member <NUM> and raceway <NUM> or perhaps only to extend member <NUM> and raceway <NUM> into the operable position after they have been pulled into the fully retracted position automatically upon opening door <NUM>. Control unit <NUM> may be programmed to perform any of such sequences.

As illustrated in the fully retracted sections IIIA and IIIB of <FIG>, member <NUM> includes a base 70b that defines an arc having a radius that at least substantially matches a radius of raceway <NUM>. It is contemplated that head <NUM> of bolt <NUM> provides a stop that is positioned (e.g., via threading bolt <NUM> into our out of member <NUM>) to stop a pivoting of raceway <NUM> caused via spring <NUM> when the radius of raceway <NUM> at least substantially reaches and thus matches the radius of the arc of base 70b. As mentioned above, raceway <NUM> is moveable primarily to allow ease of loading. A secondary benefit of the translational motion is the adjustment of the raceway position to optimize for tubing variability. Pivoting via pivot <NUM> and spring <NUM> helps to absorb tubing tolerance and provides a dampening effect which aids noise reduction. It should be appreciated that while spring <NUM> is illustrated as a compression spring, the spring may alternatively be a tension spring or other type of spring.

Referring now to <FIG>, an embodiment for any or all of pinch valve actuators 34a to 34e is illustrated. Disposable cassette <NUM>, e.g., injection or blow molded plastic, is provided with valve seats 132a to 132e that receive pinch valve actuators 34a to 34e, respectively, to occlude or close a fluid pathway <NUM> provided by the disposable cassette. In <FIG>, disposable cassette <NUM> is sealed to, e.g., ultrasonically welded, heat sealed and/or solvent bonded, and covered by a flexible sheet <NUM>, e.g., flexible plastic, portions of which pinch valve actuators 34a to 34e press into respective valve seats 132a to 132e to close a respective fluid pathway <NUM>. Pinch valve actuators 34a to 34e retract to open respective fluid pathways <NUM>. As illustrated in <FIG>, an opening in valve seats 132a to 132e extends through a rigid body <NUM> of disposable cassette <NUM> and through a port 140a to 140e extending in the opposite direction from the valve seats. A respective line or tube 122a to 122e is connected sealingly, e.g., ultrasonically welded, heat sealed and/or solvent bonded, respectively to port 140a to 140e. Line or tube 122a to 122e extends from disposable cassette <NUM> out through door <NUM> via a respective slot or aperture 26a to 26e as illustrated in <FIG>.

As illustrated in <FIG>, pinch valves 34a to 34e are each driven by a linear actuator <NUM>, which may be any suitable type of linear actuator, such as a linear stepper motor, which under control of control unit <NUM> provides a necessary amount of travel (e.g., up to <NUM>) and a needed amount of pressurized cassette sheeting closing force (e.g., <NUM> to <NUM> Newtons ("N") or less). In the illustrated embodiment, linear actuator <NUM> is mounted to an internal wall <NUM> or other internal structure inside housing <NUM> of cycler <NUM>, so that a valve plunger <NUM> connected to an output shaft <NUM> of linear actuator <NUM> extends through a hole <NUM> in actuation surface <NUM> so as to just meet a flexible valve membrane <NUM>, e.g., flexible silicone, which is bolted in place against actuation surface <NUM>. Linear actuator <NUM> drives valve plunger <NUM> to press flexible membrane <NUM> and a portion of cassette sheeting <NUM> against a respective cassette valve seat 132a to 132e. Linear actuator <NUM> retracts valve plunger <NUM> to allow the sheeting to be removed from, e.g., via its own resiliency and positive fluid pressure, a respective cassette valve seat 132a to 132e.

As illustrated in <FIG>, valve plunger <NUM> in one embodiment includes a proximal end effector <NUM> that couples to linear actuator <NUM> and a distal end effector <NUM> that is slidingly coupled to proximal end effector <NUM>. As illustrated in <FIG>, proximal end effector <NUM> includes a larger diameter portion 86a and a smaller diameter portion 86b. Distal end effector <NUM> includes or defines a cylindrical opening <NUM> that slidingly receives smaller diameter portion 86b of proximal end effector <NUM>. In the illustrated embodiment, a spring <NUM> is positioned between a step 86c transitioning between the larger and smaller diameter portions 86a, 86b and a proximal edge 90p of distal end effector <NUM>. Spring <NUM> extends over is accordingly constrained by smaller diameter portion 86b of proximal end effector <NUM>. <FIG> illustrate that an outer diameter of the distal end effector <NUM> may be at least substantially equal to that of larger diameter portion 86a of proximal end effector <NUM>.

One of proximal end effector <NUM> or distal end effector <NUM> 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 slideably attach the end effectors together. In the illustrated embodiment, proximal end effector <NUM> defines at least one groove <NUM>, while distal end effector <NUM> includes or defines a plurality of spring arms 94a, 94b. 94n, that mechanically fit, e.g., snap-fit, into the at least one groove <NUM>. If it is desirable for distal end effector <NUM> not to spin relative to proximal end effector <NUM>, then a separate groove <NUM> may be defined for each spring arm 94a, 94b. If it does not matter, then a single, annular groove <NUM> may be provided instead. In any case, the length of at least one groove <NUM> is sized to provide a length of travel of distal end effector <NUM> relative to proximal end effector <NUM>, which is equal to or greater than an uncompressed length of spring <NUM>.

Spring <NUM> may be a wave or a compression spring. One acceptable length of travel for spring <NUM> is <NUM>. In an embodiment, spring <NUM> is configured to provide a <NUM> N sealing force needed to seal cassette sheeting <NUM> properly against valve seats 132a to 132e after about <NUM> of compression travel. Spring <NUM> may at solid length exert a force up to <NUM> N, wherein linear actuator <NUM> is selected to have an at east slightly higher peak force.

Spring <NUM> is positioned so as to bias distal end effector <NUM> outwardly relative to the proximal end effector <NUM>. The variable distance provided by spring <NUM> enables pinch valve 34a to 34e to contact cassette sheeting <NUM> (via flexible membrane <NUM>) initially at a lesser closing force, which increases steadily as spring <NUM> is compressed. Flexible membrane <NUM> is fixed to actuation surface <NUM> so as to cover the end of distal end effector <NUM>. When spring <NUM> is fully compressed, cassette sheeting <NUM> and valve seat 132a to 132e see the full closing force of linear actuator <NUM> and spring <NUM>. Spring <NUM> accordingly provides a force buffer that helps to protect flexible membrane <NUM> over multiple treatments and cassette sheeting <NUM> over a single treatment. Spring <NUM> may also help with variances due to tolerance in disposable cassette <NUM> and the loading thereof, and may further allow for a smaller or less expensive linear actuator <NUM>.

Referring now to <FIG>, disposable cassette <NUM> in the illustrated embodiment provides multiple valves seats, which may include a patient line valve seat 132e, first and second supply line valve seats 132b, 132c, a last fill line valve seat 132d and a drain line valve seat 132a. In the illustrated embodiment of <FIG> and <FIG>, patient line valve seat 132e is separated fluidically from a first peristaltic tube port 142a by an inline fluid heating pathway <NUM>, e.g., a serpentine pathway. When disposable cassette <NUM> is mounted for operation, inline fluid heating pathway <NUM> is abutted against heater <NUM>, such as a resistive plate heater, illustrated in <FIG>. <FIG> illustrates that flexible sheet <NUM> is sealed to rigid body <NUM> so as to cover fluid heating pathway <NUM>, allowing heat to be transferred through the thin-walled sheeting to fresh dialysis fluid traveling through the pathway.

<FIG> and <FIG> illustrate that in one embodiment, first and second supply line valve seats 132b, 132c, last fill line valve seat 132d and a drain line valve seat 132a are each located within a common well <NUM>, which is in fluid communication with a second peristaltic tube port 142b. Peristaltic pumping tube <NUM> is attached, e.g., ultrasonically welded, heat sealed and/or solvent bonded, to tube ports 142a and 142b. Fresh dialysis fluid may accordingly be pumped from any of the supply containers 124b to 124d for the first and second supply line valve seats 132b, 132c or the last fill line valve seat 132d in a first direction through common well <NUM> and inline fluid heating pathway <NUM>, where the fresh dialysis fluid is heated, and then out the patient line valve seat 132e to the patient. Used dialysis fluid or effluent may be pumped from the patient in a second direction through the patient line valve seat 132e and inline fluid heating pathway <NUM>, where the used dialysis fluid is not heated, into the common well <NUM> and out drain line valve seat 132a to drain container 124a.

Common well <NUM> simplifies the fluid pathways for cassette <NUM>. Drain line valve seat 132a is placed closest to peristaltic tube port 142b so that used dialysis fluid travels a minimum distance within well <NUM> before reaching the drain line valve seat. <FIG>, illustrating the non-operational side of disposable cassette <NUM>, shows drain port 140a, supply container ports 140b, 140c, and last fill container port 140d extending from rigid body <NUM> on the other side from common well <NUM>. Again, drain port 140a, to which drain line 122a is ultrasonically welded, heat sealed and/or solvent bonded, is located directly adjacent to peristaltic tube port 142b, so that used dialysis fluid is removed from common well <NUM> as quickly as possible to mitigate mixing with residual fresh dialysis fluid within the well. Supply container lines 122b, 122c, last fill container line 122d and patient line 122e are likewise ultrasonically welded, heat sealed and/or solvent bonded to supply container ports 140b, 140c, last fill container port 140d port and patient line port 140e, respectively.

<FIG> and <FIG> illustrate that any of valve seats 132a to 132e described herein may include a tapered sealing surface <NUM> surrounded by a plurality of displacement ribs 154a to 154f, wherein the displacement ribs may extend from rigid body <NUM> of disposable cassette <NUM>, and wherein at least some of displacement ribs 154a to 154f are spaced apart by gaps G to prevent or mitigate against an unwanted occlusion of tapered sealing surface <NUM> by flexible sheet <NUM> and to allow fresh or used dialysis fluid to flow therethrough. Displacement ribs 154a to 154f may be completely separate from each other (see examples XC to XE in <FIG>) or extend from a common cylindrical base (see examples XA and XB in <FIG>). Displacement ribs 154a to 154f may also be separate from the tapered sealing surface <NUM> (see examples XB, XC and XE in <FIG>) or extend from or be connected to an outer edge of the tapered sealing surface (see examples XA and XD in <FIG>). Displacement ribs 154a to 154f help to guide pinch valve plunger <NUM> towards a center of the valve seat 132a to 132e, while also providing an amount of give or play between the pinch valve plunger and the valve seat. Tapered sealing surface <NUM> in an embodiment tapers to form a funnel shape leading to an opening that allows fresh or used dialysis fluid to flow into or out of valve seat 132a to 132e. In an embodiment, the opening extends through a port 140a to 140e located on the other side of rigid body <NUM> of disposable cassette <NUM> (<FIG>). Tapered sealing surface <NUM> may also include or define one or more circular sealing ring <NUM> that presses into flexible sheet <NUM> when the flexible sheet is closed by a pinch valve 34a to 34e.

In an embodiment, a first or patient pressure sensing pod 150a is located in disposable cassette <NUM> directly adjacent to patient line valve seat 132e. Patient pressure sensing pod 150a when disposable cassette <NUM> is loaded against a first or patient pressure sensor 36a, which outputs to cycler control unit <NUM>. The output of patient pressure sensor 36a may be used to control positive and negative pumping pressures experienced by the patient so as to be within safe pressure limits, e.g., within <NUM> bar (<NUM> psig) positive pressure and - <NUM> bar (-<NUM> psig) negative pressure. A second or pumping pressure sensing pod 150b is located in disposable cassette <NUM> between common well <NUM> and the second peristaltic tube port 142b. Pumping pressure sensing pod 150b when disposable cassette <NUM> is loaded is abutted against a second or pumping pressure sensor 36b, which outputs to cycler control unit <NUM>. The output of pumping pressure sensor 36b may be used to detect supply and drain line occlusions and/or supply and drain container empty conditions. For example, a jump in positive pressure from pumping pressure sensor 36b may indicate an occlusion in drain line 122a or patient line 122e. In another example, a jump in negative pressure from pumping pressure sensor 36b may indicate (i) an occlusion in patient line 122e or supply lines 122b to 122d, (ii) a supply container 124b, 124c or last fill container 124d empty condition during treatment, or (iii) a supply container 124b, 124c, last fill container 124d or drain container 124a empty condition at the end of treatment while attempting to pump any residual fresh or used treatment fluid to drain.

Disposable cassette <NUM> may also include one or more area <NUM>, which when mounted for operation abuts against a thermocouple or other type of temperature sensor <NUM> outputting to control unit <NUM>. Temperature sensing area <NUM> may for example be placed at the end of inline fluid heating pathway <NUM> directly adjacent to patient pressure sensing pod 150a, so that the outlet temperature of the fresh dialysis fluid to the patient may be monitored and controlled to a desired temperature, e.g., body temperature or <NUM> and e.g., via a proportional, integral, derivative ("PID") routine performed by control unit <NUM> using feedback from temperature sensor <NUM>. A second temperature sensor and associated cassette temperature area (not illustrated) may be located so as to detect a temperature at the inlet of inline fluid heating pathway <NUM> if needed, which may likewise provide useful information for the PID routine.

<FIG> illustrates disposable cassette <NUM> disposed vertically as it is loaded for operation against actuation surface <NUM>, wherein the cassette includes multiple features that enhance priming and air handling. Viewing <FIG> additionally, it should be appreciated that an important feature of overall system <NUM> for preventing air from reaching the patient is the location of fresh dialysis fluid supply containers or bags 124b and 124c and last fill container or bag 124d elevationally above where disposable cassette <NUM> is loaded against the actuation surface, behind door <NUM>. Here, air tends to remain in containers or bags 124b to 124d and not be delivered to disposable cassette <NUM>. Although not illustrated, it is contemplated to provide structure within and on top of bag shelf enclosure <NUM> that raises a back end of each container or bag 124b to 124d relative to a front, discharge end of the containers. In this manner, air tends to migrate towards the back of containers 124b to 124d, away from the connection of the bags to respective tubing 122b to 122d.

It is also contemplated to place air sensors or detectors (not illustrated), which may be ultrasonic sensors having emitter and receiver pairs on either side of holes or slots 26b to 26d as illustrated in <FIG>. The air sensors or detectors output to control unit <NUM>, which monitors their output signals. If air is detected, control unit <NUM> (i) stops peristaltic pump actuator <NUM> from pumping any further towards the patient (ii) closes the corresponding supply valve seat 132b to 132d illustrated in <FIG>, (iii) opens drain valve seat 132a, and (iv) reverses peristaltic pump actuator <NUM> to force the dialysis fluid having entrained air into drain line 122a and drain container 124a.

<FIG> illustrates that drain valve seat 132a is located elevationally above supply valve seat 132b to 132d to aid the air in migrating towards the drain valve seat. Additionally, the top of common well <NUM> is provided with a ramp 146r for guiding the air up towards drain valve seat 132a. <FIG> further illustrates that pumping pressure sensing pod 150b is provided with an inlet that is lower than the top of ramp 146r, such that air is encouraged to buoy away from pumping pressure sensing pod 150b up towards drain valve seat 132a. <FIG> further illustrates that the outlets of patient and pumping pressure sensing pods 150a and 150b are directed upwardly and to a relatively elevationally high location, such that air tends to leave the pods to aid in the accuracy of fresh and used dialysis fluid pressure measurements.

To aid priming, serpentine fluid heating pathway <NUM> winds upwardly to help air leave disposable cassette <NUM> during priming through patient line valve seat 132e and patient line 122e to atmosphere. Patient line valve seat 132e, like drain line valve seat 132a, is located relatively elevationally high when disposable cassette <NUM> is loaded for operation. During priming, the distal end of patient line 122e is held in a priming holder (not illustrated) located on the housing <NUM> of cycler <NUM>. An additional air detector or sensor (not illustrated) outputting to control unit <NUM>, e.g., an ultrasonic sensor, may be incorporated into the priming holder to detect when patient line 122e is fully primed with fresh dialysis fluid. It is also contemplated to place an additional air sensor or detector (not illustrated) for the patient line, which may again be an ultrasonic sensor having an emitter and receiver pair located on either side of patient line hole or slot 26e illustrated in <FIG>. The additional air sensor or detector outputs to control unit <NUM>, which monitors its output signals. If air is detected in patient line 122e, control unit <NUM> runs the air purge procedure (i) to (iv) just described, pushing the air back through fluid heating pathway <NUM> to drain container or bag 124a.

Referring now to <FIG>, cycler <NUM> of system <NUM> in one embodiment mounts pressure sensors 36a, <NUM> to, or in relation to, actuation surface <NUM> of the cycler so as to reside within a hole <NUM> in actuation surface <NUM>, and such that when disposable cassette <NUM> is loaded for operation, cassette sheeting <NUM>, which may be polyvinyl chloride ("PVC") or any of the other polymers listed herein, is contacted and placed under tension by the pressure sensor 36a, 36b, creating a baseline or preload force Fp measured by the pressure sensor. <FIG> illustrates one possible diameter for the contacting head of pressure sensor 36a, 36b, namely, <NUM>, which also provides an indication for the size or diameter of pressure pods 150a, 150b of disposable cassette <NUM>. Fresh or used dialysis fluid pressure P displaces (or attempts to displace) cassette sheeting <NUM> further and thereby increases or decreases a reaction fluid force Fr acting on pressure sensor 36a, 36b relative to baseline or preload force Fp. The force differences between Fr and Fp caused by positive or negative fluid pressure P are correlated to actual fluid pressure values by control unit <NUM>, which are used for pressure control as described herein, and which may be displayed by user interface <NUM> and/or stored for delivery to a remote server computer for evaluation.

The pre-tensioning of cassette sheeting <NUM> by pressure sensor 36a, 36b results in a pressure sensing regime having high sensitivity and resolution, but which may be prone to temperature sensitivity. It is accordingly contemplated to program control unit <NUM> to compensate pressure readings for temperature. Here, a voltage output (could alternatively be a current output) from pressure sensor 36a, 36b is modified by adding an offset component, which is a function of a measured temperature (e.g., using temperature sensor <NUM> and temperature sensing area <NUM> discussed above) multiplied by an empirically determined temperature scaling coefficient, to form a compensated voltage output, which is then converted or correlated to a compensated positive or negative pressure. One suitable scaling or offset algorithm stored in control unit <NUM> is as follows:<MAT> wherein.

<FIG> illustrates a plot used to determine the temperature scaling coefficient g for the above scaling or offset algorithm. For each of the four plot lines, the baseline or preload force Fp of pressure sensor 36a, 36b was observed during a fluid dwell period of thirty minutes for fluids maintained at different temperatures ranging from <NUM> to <NUM> (typical dialysis fluid temperatures). An equation characterizing each line was determined as illustrated in <FIG>. Each equation takes the form of y = mx + b, where (i) y is VT above, (ii) b is V<NUM> above, (iii) x is the measured temperature T above, and (iv) m is the scaling coefficient g above. The m values from each trial were averaged to form the scaling coefficient g used in the scaling or offset algorithm stored in control unit <NUM>.

In an embodiment, control unit <NUM> is configured to update the compensation algorithm for an adjustment in measured temperature T (i) each time the output from the pressure sensor is read by the control unit or (ii) on a periodic basis. Control unit <NUM> is configured to use the modified output VT from pressure sensors 36a, 36b for at least one of (a) controlling the medical fluid pump actuator to pump within a positive or negative patient pressure limit, (b) determining a line occlusion condition, and/or (c) determining a fresh or used dialysis fluid container empty condition during or after treatment.

As mentioned above, the pre-tensioning of cassette sheeting <NUM> via pressure sensors 36a, 36b results in a pressure sensing regime having high sensitivity and resolution, but which may also be prone to mechanical creep sensitivity. To combat creep sensitivity, control unit <NUM> is programmed in one embodiment to precondition cassette sheeting <NUM> prior to treatment, e.g., during setup, so that much of the variance to the pressure signal due to creep is eliminated before the measurements from pressure sensors 36a, 36b matter. To do so, control unit <NUM> after disposable cassette <NUM> is primed for treatment causes all pinch valves 34a to 34e to close and then actuates peristaltic pump actuator <NUM> so as to pressurize the inside of cassette <NUM>, including the sheeting at pressure pods 150a, 150b, to stretch the cassette sheeting. Control unit <NUM> may be programmed to cause pump actuator <NUM> to oscillate the cassette fluid pressure up and down cyclically multiple times, and perhaps in different directions, over a specified duration. An upper pressure may be, for example, from <NUM>% to <NUM>% of a maximum operational pressure set for treatment, wherein the maximum operational pressure may be higher than the patient pressure limits. For example, pressures used for priming or during the drain purge discussed above may be higher, e.g., <NUM> bars (<NUM> psig) or higher. The preconditioning of cassette sheeting <NUM> helps to make the uncompensated pressure reading more accurate, while the temperature compensation helps to make the final pressure reading more accurate.

Referring now to <FIG>, system <NUM> and cycler <NUM> of the present disclosure in one embodiment employ a weigh scale <NUM> including multiple operational load cells 102a to 102d to monitor the amount of fresh dialysis fluid delivered to the patient, the amount of used dialysis fluid removed from the patient, and from there enable control unit <NUM> to calculate an amount of ultrafiltration ("UF") removed from the patient. Weigh scales and load cells are advantageous for a number of reasons. First, weigh scale <NUM> is relatively accurate compared with other volumetric measurement techniques. Second, weigh scale <NUM> reduces the pump cost because pump actuator <NUM> may be a relatively simple peristaltic pump actuator and the disposable portion of the pump may be a simple peristaltic pump tube <NUM>.

One drawback of the use of load cells is calibration. Load cells may over time read inaccurately and therefore need to be recalibrated. Present cycler <NUM> and associated system <NUM> provide a weigh scale <NUM> having multiple load cells 102a to 102d and an onboard structure <NUM> and associated methodology for calibrating weigh scale <NUM>. In one embodiment, weigh scale <NUM> includes a weigh plate <NUM> located at the top of cycler <NUM>, which supports the weight of bag shelf enclosure <NUM> and each of the solution and drain containers 124a to 124d and associated fresh and used dialysis fluid. Weigh plate <NUM> and each of the weighted items on the weigh plate are supported by multiple, e.g., four, load cells 102a to 102d that collectively measure the total mass placed on the weigh plate (bag shelf enclosure <NUM>, containers 124a to 124d and fluids). Onboard calibration structure <NUM> in one embodiment includes a linear actuator <NUM> (may be of the same type as used for the pinch valves, e.g., include a motor and lead screw or a linear stepper motor) and a fifth or calibration load cell <NUM> located beneath linear actuator <NUM>, wherein linear actuator <NUM> includes an actuation output shaft <NUM>, which is fixed to weigh plate <NUM>. Actuation output shaft <NUM> may for example extend through a hole formed in weigh plate <NUM> and be capped above the upper surface of the weigh plate so as to be able to provide a downward force onto the plate. Actuation output shaft <NUM> may alternatively include a flange that is bolted to the underside of weigh plate <NUM> or that slides into a groove formed on the underside of weigh plate <NUM>, be threaded to thread into the underside of weigh plate <NUM>, or have some alternative mechanical connection to weigh plate <NUM>.

Linear actuator <NUM> in one embodiment is actuated so as to apply a pulling or downward force to of weigh plate <NUM>. In one implementation, the force is applied to the center of mass CM of weigh plate <NUM> as illustrated in <FIG>. Operational load cells 102a to 102d in an embodiment are each at least substantially equidistant from the center of mass CM and are spread out from each other in equal x-coordinate distances (e.g., the distance between the contact points of load cells 102a and 102b being the same as the distance between the contact points of load cells 102d and 102c), and in equal y-coordinate distances (e.g., the distance between the contact points of load cells 102a and 102d being the same as the distance between the contact points of load cells 102b and 102c).

Additional calibration load cell <NUM> measures the total pulling or downward force applied by linear actuator <NUM>, while the four operational load cells 102a to 102d each measure a fraction or fourth of the total force. If operational load cells 102a to 102d are each performing properly, the sum of their outputs should equal the total force measured by calibration load cell <NUM>. In an example, suppose <NUM> Newtons ("N") of pulling force is applied by linear actuator <NUM>. Calibration load cell <NUM> should output <NUM> N, while operational load cells 102a to 102d should each read <NUM> Newtons, totaling in combination <NUM> N.

Because calibration load cell <NUM> is used infrequently, the calibration algorithm is applied assuming that the output of calibration load cell <NUM> is more accurate than the collective output of the operational load cells 102a to 102d, which are used throughout each treatment. So if during calibration there is a mismatch between what the calibration load cell <NUM> reads versus the collective output of the operational load cells 102a to 102d, control unit <NUM> using the calibration algorithm scales or offsets the collective output of the operational load cells 102a to 102d to match that of the calibration load cell <NUM>. In the above example, suppose operational load cells 102a to 102d actually collectively read <NUM> N instead of <NUM> N. Operational load cells 102a to 102d are accordingly reading low by <NUM>%. Control unit <NUM> of cycler <NUM> is thereby configured during treatment to modify the collective output of the operational load cells 102a to 102d by a calibration factor of <NUM>/<NUM> or <NUM>.

The load cell calibration routine or algorithm of system <NUM> is performed on some desired basis, e.g., before the start of each treatment. Control unit <NUM>, for example, controls a duration of an operation (patient fill or drain) of pump actuator <NUM> using offsetted output pressures from operational load cells 102a to 102d. Control unit <NUM> is configured to cause linear actuator <NUM> to not supply any force during such duration of operation. Control unit <NUM> in another example is configured to use two or more offsetted outputs from operational load cells 102a to 102d to determine a mass or volumetric flowrate during treatment. In a further example, control unit <NUM> is configured to determine an amount of fresh dialysis fluid delivered using at least two offsetted outputs from the operational load cells 102a to 102d. In yet another example, control unit <NUM> is configured to determine an amount of used dialysis fluid delivered using at least two offsetted outputs from the operational load cells 102a to 102d. In yet a further example, control unit <NUM> is configured to determine an amount of fresh dialysis fluid delivered to or used dialysis fluid removed from a patient using at least two offsetted outputs from the operational load cells 102a to 102d.

It should also be appreciated that because many of the weight values monitored and collected during treatment are weight differences, error in the collective output of operational load cells 102a to 102d tends to cancel itself out, assuming that the error does not change over the course of treatment. For example, the mass associated with a patient fill volume of, e.g., two liters is monitored and controlled by the collective output of the operational load cells 102a to 102d by recording a drop in mass over the course of the patient fill. The volume and mass associated with a patient drain may be preset in control unit <NUM>, e.g., be a factor, such as <NUM>, multiplied by the fill volume to account for patient UF removed into the drain volume. The volume and mass associated with a patient drain may alternatively be left open-ended and be controlled instead by the sensing of a characteristic rise in negative pressure by pumping pressure sensing pod 150b and associated pressure sensor 36b, indicating that the patient is essentially fully drained and that further draining may be uncomfortable for the patient. In either case, operational load cells 102a to 102d sense an increase in weight over the course of the patient drain, which should tend to cancel any error in the operational load cells.

Claim 1:
A peritoneal dialysis system (<NUM>) comprising:
a cycler (<NUM>) including a pump actuator (<NUM>);
a disposable set (<NUM>) including
a pumping portion (<NUM>) operable with the pump actuator (<NUM>),
a patient line (122e) positioned to fluidly communicate with the pumping portion (<NUM>), and
a drain container (124a) positioned to fluidly communicate with the pumping portion (<NUM>); and
a control unit (<NUM>),
characterized in that the control unit is configured to cause the pump actuator (<NUM>) to actuate the pumping portion (i) to run a peritoneal dialysis treatment in which fresh dialysis fluid is pumped through the patient line (122e) to a patient and used dialysis fluid is pumped from the patient to the drain container (124a), and (ii) at the end of the peritoneal dialysis treatment, to pump the used dialysis fluid from the drain container (124a), through the patient line (122e), to a house drain.