CN119968217A

CN119968217A - Peritoneal dialysis system using cylinder and optional air pump

Info

Publication number: CN119968217A
Application number: CN202380072588.9A
Authority: CN
Inventors: 珊莎库马尔·莎珊卡·贾殷·贝卢尔
Original assignee: Baxter Healthcare SA; Baxter International Inc
Current assignee: Baxter Healthcare SA; Baxter International Inc
Priority date: 2022-10-14
Filing date: 2023-10-05
Publication date: 2025-05-09
Also published as: WO2024081155A1; EP4577262A1

Abstract

In one example, a control unit (i) causes a second pneumatic valve and a source fluid valve to open and causes a linear actuator to move a piston head into a first cylinder chamber so as to create a negative pressure in the pneumatic pump chamber, thereby pulling the source fluid into the fluid pump chamber, and (ii) causes a first pneumatic valve and a destination fluid valve to open and causes the linear actuator to move the piston head into the first cylinder chamber, thereby pushing the source fluid through the destination fluid valve, the control unit using the pressure sensor reading to control the linear actuator so that a final pressure for (ii) is at least substantially equal to an initial pressure for (ii) so that a volume of a space corresponding to the movement of the piston head within the cylinder during (ii) is equal to a volume of the source fluid delivered from the fluid pump chamber.

Description

Peritoneal dialysis system using a cylinder and optional air pump

Technical Field

The present disclosure relates generally to medical fluid treatment, and in particular to dialysis fluid treatment.

Background

The human renal system may fail for various reasons. Renal failure can produce several physiological disorders. No longer can balance water and minerals or no longer can excrete daily metabolic loads. Toxic end products of metabolism (such as urea, creatinine, uric acid, and other substances) may accumulate in the blood and tissues of patients.

Dialysis is used to treat reduced kidney function, especially kidney failure. Dialysis removes waste, toxins and excess water from the body that would otherwise be removed by a normal functioning kidney. Dialysis treatment for replacing kidney function is critical to many people because such treatment is life-saving.

One type of kidney failure therapy is hemodialysis ("HD"), which generally uses diffusion to remove waste products from the patient's blood. A diffusion gradient occurs across the semipermeable dialyzer between the blood and the electrolyte solution (which is referred to as a dialysate or dialysis fluid) to cause diffusion.

Hemofiltration ("HF") is an alternative renal replacement therapy that relies on convective transport of toxins from the patient's blood. HF is achieved by adding replacement or substitution fluids to the extracorporeal circuit during treatment. During HF treatment, the replacement fluid and the fluid that the patient has accumulated between treatments are ultrafiltered, providing a convective transport mechanism that is particularly advantageous for removing medium and macromolecules.

Hemodiafiltration ("HDF") is a treatment that combines convective clearance and diffusive clearance. Similar to standard hemodialysis, HDF uses a dialysis fluid flowing through a dialyzer to provide diffusion clearance. In addition, the replacement solution is provided directly to the extracorporeal circuit, thereby providing convective clearance.

Most HD, HF and HDF treatments are centrally performed. There is a trend today towards home hemodialysis ("HHD"), in part because HHD can be performed daily, which provides therapeutic benefits over central hemodialysis treatments, which are typically performed every two or three weeks. Studies have shown that more frequent treatments remove more toxins and waste and provide less overload of the dialysis fluid than patients receiving less frequent but possibly longer treatments. Patients receiving more frequent treatment do not experience as much descending circulation (fluctuation of fluid and toxins) as central patients who have accumulated two or three days prior to treatment. In some areas, the nearest dialysis center may be many miles away from the patient's home, which results in a significant portion of the day being taken up for treatment. Treatment at a center near the patient's home may also take up a substantial portion of the patient's day. HHD can be performed during the night or during the day while the patient is relaxed, working or otherwise producing.

Another type of kidney failure therapy is peritoneal dialysis ("PD") which infuses a dialysis solution (also referred to as a dialysis fluid) into the peritoneal chamber of a patient via a catheter. The dialysis fluid is contacted with the peritoneum within the patient's peritoneal cavity. Waste, toxins and excess water pass from the patient's blood stream through capillaries in the peritoneum and enter the dialysis fluid due to diffusion and osmosis, i.e. an osmotic gradient occurs across the peritoneum. The osmotic agent in the PD dialysis fluid provides an osmotic gradient. Spent or depleted dialysis fluid is drained from the patient, thereby removing waste, toxins, and excess water from the patient. This cycle is repeated, for example, a plurality of 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 the implanted catheter to the drain to allow the spent or depleted dialysis fluid to drain from the peritoneal chamber. The patient then switches fluid communication such that the patient conduit communicates with the bag of fresh dialysis fluid to pass fresh dialysis fluid through the conduit and infuse into the patient. The patient disconnects the catheter from the fresh dialysis fluid bag and allows the dialysis fluid to reside within the peritoneal cavity, where transfer of waste, toxins and excess water occurs. After the dwell period, the patient repeats the manual dialysis procedure, for example four times per day. Manual peritoneal dialysis requires a great deal of time and effort from the patient, leaving a great deal of room for improvement.

Automated peritoneal dialysis ("PD") is similar to CAPD in that dialysis treatment includes an evacuation cycle, a fill cycle, and a dwell cycle. However, automated PD machines typically perform these cycles automatically while the patient sleeps. Automated PD machines eliminate the need for the patient to manually perform a treatment cycle, nor to deliver supplies during the day. The automated PD machine is fluidly connected to an implanted catheter, a source or bag of fresh dialysis fluid, and a fluid drain. The automated PD machine pumps fresh dialysis fluid from a dialysis fluid source through the catheter and into the peritoneal cavity of the patient. The automated PD machine also allows dialysis fluid to reside within the peritoneal cavity and allows transfer of waste, toxins and excess water to occur. The source may comprise a multi-liter dialysis fluid comprising a number of solution bags.

APD machines pump spent or depleted dialysate from the peritoneal chamber through a conduit to a drain. As with the manual process, several drain, fill, and dwell cycles occur during dialysis. The "final fill" can occur at the end of APD treatment. The last fill fluid may remain in the patient's peritoneal chamber until the beginning of the next treatment, or may be manually emptied at some point during the day.

In any of the above modalities of using an automated machine, the automated machine typically operates with a disposable set that is discarded after a single use. Depending on the complexity of the disposable set, the cost of using one set per day may become significant. Moreover, daily disposables require space for storage, which can be cumbersome for homeowners and businesses. Furthermore, replacement of the daily disposable requires the daily setup time and effort of the patient or the caretaker at home or in a clinic.

The APD device also needs to be portable so that the patient can take his or her device on vacation or for work travel. Furthermore, APD devices need to have pumping precision so that the device can accurately track how much ultrafiltration ("UF") is removed from the patient during treatment.

For each of the reasons described above, it is desirable to provide a relatively simple, compact dialysis machine, such as an APD machine, that is accurate and simple to operate and cost effective disposable kit.

Disclosure of Invention

The present disclosure relates to a peritoneal dialysis ("PD") machine or circulator driven by a cylinder and an optional air pump. In the first main embodiment, only the cylinder is provided. The cylinder is located between the first and second pneumatic pump chambers. A piston is located within the cylinder, wherein the piston includes a piston head dividing the cylinder into a first cylinder chamber and a second cylinder chamber. A first pneumatic line extends from the first cylinder chamber to the first pneumatic pump chamber. A second pneumatic line extends from the second cylinder chamber to the second pneumatic pump chamber. The first pressure sensor is positioned to read air pressure in the first pneumatic line, the first pneumatic pump chamber, and the first cylinder chamber. The second pressure sensor is positioned to read air pressure in the second pneumatic line, the second pneumatic pump chamber, and the second cylinder chamber.

A first exhaust line and associated first exhaust valve are optionally placed in fluid communication with the first cylinder chamber. A second exhaust line and associated second exhaust valve are optionally placed in fluid communication with the second cylinder chamber. The piston also includes a piston shaft coupled to the linear actuator outside of the cylinder for translating the piston shaft and the piston head within the cylinder.

All valves, motors of linear actuators, PD fluid heaters, and other controllable electrical equipment are under the control of a control unit that includes at least one processor, at least one memory, and a video controller for controlling a user interface. The control unit is also configured to receive signals from all sensors such as pneumatic pressure sensors, fluid pressure sensors (if provided), motor encoders (for linear actuators if provided), and any temperature sensors associated with the heater. The control unit is programmed to run all of the pumping sequences discussed herein.

In one embodiment, the PD machine or cycler operates with a disposable set. The disposable set includes, among other things, first and second fluid pump chambers that operate with the first and second pneumatic pump chambers, respectively. When the piston head moves to create a negative pneumatic pressure within the first cylinder chamber or the second cylinder chamber, a corresponding negative pressure is created in the respective first pneumatic pump chamber or second pneumatic pump chamber. The negative pressure generated in the first or second pneumatic pump chamber in turn pulls the flexible membrane of the corresponding first or second fluid pump chamber into the first or second pneumatic pump chamber such that the fluid pump chamber is filled with fresh or used PD fluid. When the piston head moves to generate positive pneumatic pressure within the first cylinder chamber or the second cylinder chamber, a corresponding positive pressure is generated in the respective first pneumatic pump chamber or second pneumatic pump chamber. The positive pressure generated in the first or second pneumatic pump chamber in turn pushes against the flexible membrane of the corresponding first or second fluid pump chamber, causing the fluid pump chamber to close and expel fresh or used PD fluid.

The control unit in the first main embodiment causes the piston shaft to translate the piston head back and forth within the cylinder such that in one half stroke (i) the first pump chamber is filled with fresh or used PD fluid and the second fluid pump chamber discharges fresh or used PD fluid. In the second half stroke (ii), the second pump chamber is filled with fresh or used PD fluid, while the first fluid pump chamber is drained of fresh or used PD fluid. The control unit translates the piston head back and forth in the manner described above until a desired or prescribed volume of fresh or used PD fluid from a desired PD fluid source is delivered to a desired PD fluid destination. A fluid valve is provided and sequentially actuated by the control unit to access the desired fluid source and the desired fluid destination. The fluid valve may be, for example, a magnetically actuated solenoid valve, an electrically actuated pinch valve, or a pneumatically actuated valve.

In a first main embodiment, and in the event that patient pumping is taking place such that pressure control is important, the control unit monitors the output from the first and second pressure sensors while the piston head translates back and forth. The control unit controls the speed of the back and forth translation so that the desired safe negative or positive fluid pumping pressure is not exceeded.

In a first main embodiment, the amount of fresh or used PD fluid delivered to the destination is determined by maintaining a constant pressure before and after the piston head moves, which counteracts the compressible effect of in-cylinder air. Since the post-movement pressure (P2) is equal to the pre-movement pressure (P1), the volume of air in the cylinder remains constant. Thus, the volume displaced by the piston head is equal to the volume of fluid being delivered.

In a second main embodiment, only the cylinders are provided as before, but wherein the cylinders are dedicated to a single pneumatic pump chamber/fluid pump chamber pair. Two pneumatic pump chamber/fluid pump chamber pairs may be provided, each pair having its own dedicated cylinder. The cylinder is of the same construction as in the first main embodiment, including a piston head and a piston shaft driven by a linear actuator. An optional exhaust line and pneumatic exhaust valve may be in pneumatic communication with the first and second chambers of each cylinder.

In a second main embodiment, the first pneumatic line and the second pneumatic line extend from the first cylinder chamber and the second cylinder chamber, respectively, to the same pneumatic pump chamber. First and second pneumatic valves disposed along the first and second pneumatic lines under the control of the control unit. One or more pressure sensors are provided along a common portion of the first pneumatic line and the second pneumatic line or along each of the first pneumatic line and the second pneumatic line. The fluid pump chamber is again provided as part of the disposable set, wherein the fluid pump chamber pumps fresh or used PD fluid from a desired PD fluid source to a desired destination, as determined by the sequence of one or more fluid valves.

The control unit in the second main embodiment causes the piston shaft to translate the piston head toward one of the first cylinder chamber or the second cylinder chamber (e.g., the first cylinder chamber), thereby generating positive pressure in the first cylinder chamber and negative pressure in the second cylinder chamber. The control unit also opens the source fluid valve and the second pneumatic valve so as to allow negative pressure to reach the pneumatic pump chamber and so that the flexible membrane is pulled into the pneumatic pump chamber and filled with fresh or used PD fluid.

Next, the control unit causes the source fluid valve and the second pneumatic valve to close and causes the first pneumatic valve to open so that the pressure sensor can read the positive pressure in the first cylinder chamber. The control unit also moves the piston into the first cylinder chamber such that the positive pressure in the pneumatic pump chamber reads a desired pressure, e.g., 1.5psig, to pump fresh or used PD fluid to a desired destination. At the end of this movement, the piston head is in the initial piston head position.

Next, the control unit maintains the first pneumatic valve in an open state and opens the destination fluid valve. The desired positive pressure established in the pneumatic pump chamber forces the flexible membrane of the fluid pump chamber to collapse and push fresh or used PD fluid to the desired destination. As the positive pressure dissipates, the control unit moves the piston further into the first cylinder chamber so that the pressure sensor continues to read the desired pressure, e.g., 1.5psig.

Eventually, the flexible membrane cannot collapse further, resulting in the pressure sensor reading peaking, at which point the control unit stops the pump-out translation of the piston head and closes the destination fluid valve. Alternatively or additionally, detection that the flexible membrane cannot collapse further may be determined by the control unit detecting that the linear actuator and/or piston head is not moving while maintaining a desired pressure (e.g., 1.5 psig). In any case, after stopping the pump-out translation, the first pneumatic valve remains open to allow the positive pressure that has been maintained at the desired pressure to equilibrate between the first cylinder chamber and the pneumatic pump chamber, and this positive pressure can be read by the pressure sensor. The piston head is now in the final piston head position. The volume difference between the cylinder at the known cross-sectional area between the final piston head position and the initial piston head position is the volume of fresh or used PD fluid pumped to the desired destination due to the same pressure at the initial piston head position and the final piston head position (e.g., 1.5psig, which is the desired pump-to-patient pressure). That is, the volume of the space corresponding to the movement of the piston head within the cylinder varies with the distance the piston head moves within the cylinder and the cross-sectional area of the inner diameter of the cylinder.

Next, with the second cylinder chamber still under negative pressure (which is not critical if pulled from a non-patient source), the control unit opens the source fluid valve and the second pneumatic valve, allowing negative pressure to reach the pneumatic pump chamber and the flexible membrane to be pulled into the pneumatic pump chamber and filled with fresh or used PD fluid.

Next, the control unit closes the source fluid valve but allows the second pneumatic valve to remain open such that the pneumatic pump chamber and the second cylinder chamber remain exposed to the pressure sensor. The control unit translates the piston into the second chamber until the pressure sensor reads zero psig. The pressure in the first cylinder chamber should also be near zero psig.

Next, with the source and destination fluid valves closed, the first pneumatic valve closed, and the second pneumatic valve open so that the pressure sensor can read the positive pressure in the second cylinder chamber, the control unit moves the piston into the second cylinder chamber so that the positive pressure in the pneumatic pump chamber again reads the desired pressure for pumping fresh or used PD fluid to the desired destination, e.g., 1.5psig. At the end of this movement, the piston head is again in the initial piston head position.

Next, the control unit maintains the second pneumatic valve in an open state and opens the destination fluid valve. The desired positive pressure established in the pneumatic pump chamber again forces the flexible membrane of the fluid pump chamber to collapse and push fresh or used PD fluid to the desired destination. As the positive pressure dissipates, the control unit moves the piston further into the second cylinder chamber so that the pressure sensor continues to read the desired pressure, e.g., 1.5psig.

Eventually, the flexible membrane cannot collapse further, resulting in the pressure sensor reading peaking, at which point the control unit stops the pump-out translation of the piston head and closes the destination fluid valve. Alternatively or additionally, detection that the flexible membrane cannot collapse further may again be determined by the control unit detecting that the linear actuator and/or piston head is not moving while maintaining a desired pressure (e.g., 1.5 psig). In any case, after stopping the pump-out translation, the second pneumatic valve remains open to allow the positive pressure that has been maintained at the desired pressure to equilibrate between the first cylinder chamber and the pneumatic pump chamber, and this positive pressure can be read by the pressure sensor. The piston head is now in the final piston head position. The volumetric difference between the cylinder at the final piston head position and the initial piston head position at the known cross-sectional area is again due to the same pressure at the initial piston head position and the final piston head position (e.g., 1.5psig, which is the desired pump-to-patient pressure) to pump the volume of fresh or used PD fluid to the desired destination.

With the first cylinder chamber still under negative pressure (which is not critical if pulled from a non-patient source), the control unit causes the source fluid valve and the first pneumatic valve to open, allowing the negative pressure to reach the pneumatic pump chamber and the flexible membrane to be pulled into the pneumatic pump chamber and filled with fresh or used PD fluid. The above process is repeated until the desired amount of fresh or used PD fluid is delivered to the desired destination. It should be appreciated that the above-described process may be used with any of the fresh or used PD fluid sources and any of the fresh or used PD fluid destinations described herein, and that suction pressure and delivery pressure, as well as delivered PD fluid volume, may be controlled and measured, respectively.

The third main embodiment describes an air pump that operates in cooperation with an air cylinder. The air pump may generally transition more quickly between a positive pumping pressure and a negative pumping pressure and vice versa. Moreover, even a small air pump can generate a wide range of pressure. These two advantages of air pumps are combined with the ability of the air cylinder to meter a known volume of fluid under pressure control as described herein.

The structure of the cylinder in the third main embodiment is substantially the same as that in the first and second main embodiments, and includes a piston head and a piston shaft driven by a linear actuator. An optional exhaust line and pneumatic exhaust valve may be in pneumatic communication with the first and second chambers of each cylinder. In a third main embodiment, only the first pneumatic line extends from the cylinder to the pneumatic pump chamber. A first pneumatic valve is provided along the first pneumatic line under the control of the control unit. A second pneumatic line extends from the air pump and intersects the first pneumatic line. A second pneumatic valve is provided along the second pneumatic line under control of the control unit. The pressure sensor is disposed along a common portion of the first pneumatic line and the second pneumatic line. One or more fluid pump chambers are again provided as part of the disposable set, wherein the fluid pump chambers pump fresh or used PD fluid from a desired PD fluid source to a desired destination, as determined by the sequence of one or more fluid valves.

The control unit in the third main embodiment initially opens the first and second pneumatic valves, opens the source fluid valve, and causes the air pump to create a negative pressure in the pneumatic pump chamber and the cylinder chamber, thereby pulling the flexible membrane of the fluid pump chamber into the pneumatic pump chamber and pulling fresh or used PD fluid into the fluid pump chamber. In an embodiment, the control unit monitors the speed of the air pump during the PD fluid extraction phase. When the speed of the air pump starts to decrease, the control unit determines that the flexible membrane is pulled and inflated completely, so that the fluid pump chamber is filled with fresh or used PD fluid. Once the flexible membrane is fully pulled, the speed of the air pump is reduced. The control unit provides closed loop control to the air pump so that the desired pressure is maintained. A control loop via the control unit ensures that the pressure does not extend beyond the set threshold.

After the fluid pump chamber is completely filled with PD fluid, the control unit causes the source fluid valve to close. The control unit then causes the first pneumatic valve and the second pneumatic valve to open and causes the air pump to generate a desired positive pumping pressure (e.g., 1.5 psig) in the pneumatic pump chamber and the cylinder chamber. Once the desired positive pumping pressure is reached, the control unit causes the second pneumatic valve to close such that the air pump is isolated and blocked. The piston head of the piston is in the initial piston head position.

The control unit then maintains the first pneumatic valve in an open state and causes the destination fluid valve to open. The desired positive pressure established in the pneumatic pump chamber forces the flexible membrane of the fluid pump chamber to collapse and push fresh or used PD fluid to the destination. As the positive pressure dissipates, the control unit moves the piston within the cylinder chamber so that the pressure sensor continues to read the desired pressure, e.g., 1.5psig.

Eventually, the flexible membrane cannot collapse further, resulting in the pressure sensor reading peaking, at which point the control unit stops the pump-out translation of the piston head and closes the destination fluid valve. Alternatively or additionally, detection that the flexible membrane cannot collapse further may again be determined by the control unit detecting that the linear actuator and/or piston head is not moving while maintaining a desired pressure (e.g., 1.5 psig). In any event, after stopping the pump-out translation, the first pneumatic valve remains open to allow the positive pressure that has been maintained at the desired pressure to equilibrate between the cylinder chamber and the pneumatic pump chamber, and this positive pressure can be read by the pressure sensor. The piston head is now in the final piston head position. The volume difference in the cylinder at the known cross-sectional area between the final piston head position and the initial piston head position is the volume of fresh PD fluid pumped to the destination due to the same pressure at the initial piston head position and the final piston head position (e.g., 1.5psig, which is the desired pump-to-patient pressure).

The control unit then opens the first pneumatic valve and the second pneumatic valve, opens the source fluid valve, and moves the piston in the opposite direction within the cylinder to reposition the piston head for the next pump-out stroke. The movement of the piston creates a negative pressure within the cylinder chamber and the pneumatic pump chamber, which may be aided by an air pump to quickly achieve a desired PD fluid extraction pressure. The flexible membrane of the fluid pump chamber is pulled into the pneumatic pump chamber and fresh or used PD fluid is correspondingly pulled into the fluid pump chamber. The above procedure for the third main embodiment is repeated, wherein the control unit accumulates the pump stroke volume until a desired or prescribed amount of fresh or used PD fluid is delivered to the destination.

The fourth main embodiment also uses an air pump that operates in cooperation with the air cylinder. Here, a single air pump and cylinder can drive two fluid pump chambers within two pneumatic pump chambers. The structure of the cylinder in the fourth main embodiment is the same as that in the third main embodiment, and includes a piston head and a piston shaft driven by a linear actuator. An optional exhaust line and pneumatic exhaust valve may be in pneumatic communication with the first and second chambers of each cylinder. In a fourth main embodiment, although only the first pneumatic line extends from the cylinder, the first pneumatic line diverges so as to further include a second pneumatic line, wherein the first pneumatic line and the second pneumatic line extend to the first pneumatic pump chamber and the second pneumatic pump chamber, respectively. The first pneumatic valve and the second pneumatic valve under control of the control unit are disposed along the first pneumatic line and the second pneumatic line, respectively.

A third pneumatic line extends from the air pump and diverges into a fourth pneumatic line. The third pneumatic line intersects the first pneumatic line and the fourth pneumatic line intersects the second pneumatic line. A third pneumatic valve is provided along the third pneumatic line under control of the control unit, and a fourth pneumatic valve is provided along the fourth pneumatic line under control of the control unit. The first pressure sensor is disposed adjacent the first pneumatic pump chamber and the second pressure sensor is disposed adjacent the second pneumatic pump chamber. The first fluid pump chamber and the second fluid pump chamber are provided as part of a disposable set, wherein the first fluid pump chamber and the second fluid pump chamber pump fresh or used PD fluid from a desired PD fluid source to a desired PD fluid destination, as determined by a sequence of a plurality of fluid valves.

In the pumping sequence of the fourth main embodiment, the first and second fluid pumping chambers are typically alternating, wherein when one fluid pumping chamber draws fresh or used PD fluid, the other fluid pumping chamber pushes fresh or used PD fluid out. Each fluid pump chamber has its own set of source and destination valves, however, complete synchronization of the first and second fluid pump chambers is not required.

The control unit in the fourth main embodiment initially causes the third pneumatic valve and the source fluid valve for the first fluid pump chamber to open and causes the air pump to create a negative pressure in the first pneumatic pump chamber, thereby pulling the flexible membrane of the first fluid pump chamber into the first pneumatic pump chamber and pulling fresh or used PD fluid into the first fluid pump chamber. During the PD fluid extraction phase, the control unit may again monitor the speed of the air pump. When the speed of the air pump begins to decrease beyond the set threshold, the control unit determines that the flexible membrane is fully pulled and inflated, and thus the fluid pump chamber is filled with fresh or used PD fluid, at which point the control unit stops the air pump and closes the source fluid valve for the first fluid pump chamber. The control unit then maintains the third pneumatic valve in an open state and causes the air pump to generate a desired positive pumping pressure in the first pneumatic pump chamber (e.g., 1.5psig as read by the first pressure sensor). At this time, the piston head of the piston of the cylinder is in the initial piston head position.

The control unit then closes the third pneumatic valve, opens the first pneumatic valve, and opens the first destination fluid valve. The desired positive pressure established in the first pneumatic pump chamber forces the flexible membrane of the first fluid pump chamber to collapse and push fresh or used PD fluid to the destination. As the positive pressure dissipates, the control unit moves the piston within the cylinder chamber so that the first pressure sensor continues to read the desired pressure, e.g., 1.5psig. At the same time, the control unit opens the fourth pneumatic valve, opens the second source valve, and causes the air pump to create a negative pressure in the second pneumatic pump chamber, thereby pulling the flexible membrane of the second fluid pump chamber into the second pneumatic pump chamber and pulling fresh or used PD fluid into the second fluid pump chamber.

Eventually, the first flexible membrane cannot collapse further, causing the first pressure sensor reading to peak, at which point the control unit stops the pump-out translation of the piston head and closes the first destination fluid valve. Alternatively or additionally, detection that the flexible membrane cannot collapse further may be determined by the control unit detecting that the linear actuator and/or piston head is not moving while maintaining a desired pressure (e.g., 1.5 psig). In any event, after stopping the pump-out translation, the first pneumatic valve remains open to allow the positive pressure that has been maintained at the desired pressure to equilibrate between the cylinder chamber and the first pneumatic pump chamber, and this positive pressure can be read by the first pressure sensor. The piston head is now in the final piston head position within the cylinder chamber. The volume difference in the cylinder at the known cross-sectional area between the final piston head position and the initial piston head position is the volume of fresh or used PD fluid pumped to the destination due to the same pressure at the initial piston head position and the final piston head position (e.g., 1.5psig, which is the desired pump-to-patient pressure). For fluid extraction from the second fluid pump chamber, the control unit may again monitor the speed of the air pump. When the speed of the air pump begins to decrease beyond the set threshold, the control unit determines that the flexible membrane of the second fluid pump chamber is fully pulled and inflated, and thus the second fluid pump chamber is filled with fresh or used PD fluid, at which point the control unit stops the air pump and closes the second source fluid valve for the second fluid pump chamber.

The control unit then retracts the piston to the initial position and repeats the above procedure, but wherein the first fluid pump chamber is filled with fresh or used PD fluid and the second fluid pump chamber pushes the fresh or used PD fluid to the destination. The control unit accumulates the known stroke volume and continues to perform the alternating pumping sequence just described until a desired or prescribed amount of fresh or used PD fluid is delivered to the destination.

Similar to the fourth main embodiment, the fifth main embodiment also uses an air pump that operates in cooperation with an air cylinder to drive two pneumatic pump chambers and corresponding fluid pump chambers. In a fourth main embodiment, the cylinder is unidirectional with respect to fluid volume metering in that only one side of the piston head within the cylinder is exposed to the first and second pressure sensors. After each fluid pump chamber extraction/fluid pump chamber delivery sequence, the piston needs to be reset accordingly. In a fifth main embodiment, a fifth pneumatic line is added, which extends from the first pneumatic line to the opposite side of the cylinder, such that there is pneumatic access to the cylinder on both sides of the piston head. The fifth pneumatic valve is provided with a fifth pneumatic line. A sixth pneumatic valve is added along the first pneumatic line as a second valve, which allows closing the cylinder on that side of the piston head.

In a pumping sequence using the fifth main embodiment, the control unit may cause the second pneumatic valve and the fifth pneumatic valve to open, cause the second destination fluid valve to open, and cause the piston head of the cylinder to move in the first direction to deliver fresh or used PD fluid from the second fluid pump chamber to the desired destination. At the same time, the control unit opens the third pneumatic valve and the first source fluid valve so that the air pump can apply negative pressure to the flexible membrane of the first fluid pump chamber, thereby pulling fresh or used PD fluid into the first fluid pump chamber.

Eventually, the second flexible membrane cannot collapse further, causing the second pressure sensor reading to peak, at which point the control unit stops the pump-out translation of the piston head and closes the second destination fluid valve. Alternatively or additionally, detection that the flexible membrane cannot collapse further may again be determined by the control unit detecting that the linear actuator and/or piston head is not moving while maintaining a desired pressure (e.g., 1.5 psig). In any event, after stopping the pump-out translation, the second pneumatic valve and the fifth pneumatic valve remain open to allow the positive pressure that has been maintained at the desired pressure to equilibrate between the cylinder chamber and the second pneumatic pump chamber, and this positive pressure can be read by the second pressure sensor. The volume difference in the cylinder at the known cross-sectional area between the initial piston head position and the final piston head position is the volume of fresh or used PD fluid pumped to the destination due to the same pressure at the initial piston head position and the final piston head position (e.g., 1.5psig, which is the desired pump-to-patient pressure). For fluid extraction from the first fluid pump chamber, the control unit may again monitor the speed of the air pump. When the speed of the air pump begins to decrease beyond the set threshold, the control unit determines that the flexible membrane of the first fluid pump chamber is fully pulled and inflated and thus the first fluid pump chamber is filled with fresh or used PD fluid, at which point the control unit stops the air pump and closes the first source fluid valve for the first fluid pump chamber.

Next, the first fluid pump chamber and the second fluid pump chamber are switched in operation such that the second fluid pump chamber draws fresh or used PD fluid while the first fluid pump chamber delivers fresh or used PD fluid. Notably, there is no need to adjust the piston head to prepare the cylinder for the switch. Here, the control unit opens the first pneumatic valve and the sixth pneumatic valve, opens the first destination fluid valve, and moves the piston head of the cylinder in the second direction to deliver fresh or used PD fluid from the first fluid pump chamber to the desired destination. At the same time, the control unit opens the fourth pneumatic valve and the second source fluid valve so that the air pump can apply negative pressure to the flexible membrane of the second fluid pump chamber, thereby pulling fresh or used PD fluid into the second fluid pump chamber.

Eventually, the first flexible membrane cannot collapse further, causing the first pressure sensor reading to peak, at which point the control unit stops the pump-out translation of the piston head and closes the first destination fluid valve. Alternatively or additionally, detection that the flexible membrane cannot collapse further may again be determined by the control unit detecting that the linear actuator and/or piston head is not moving while maintaining a desired pressure (e.g., 1.5 psig). In any case, after stopping the pump-out translation, the first and sixth pneumatic valves remain open to allow the positive pressure that has been maintained at the desired pressure to equilibrate between the cylinder chamber and the first pneumatic pump chamber, and this positive pressure can be read by the first pressure sensor. The volume difference in the cylinder at the known cross-sectional area between the initial piston head position and the final piston head position is the volume of fresh or used PD fluid pumped to the destination due to the same pressure at the initial piston head position and the final piston head position (e.g., 1.5psig, which is the desired pump-to-patient pressure). For fluid extraction from the second fluid pump chamber, the control unit may again monitor the speed of the air pump. When the speed of the air pump begins to decrease beyond the set threshold, the control unit determines that the flexible membrane of the second fluid pump chamber is fully pulled and inflated, and thus the second fluid pump chamber is filled with fresh or used PD fluid, at which point the control unit stops the air pump and closes the second source fluid valve for the second fluid pump chamber.

The control unit accumulates the known stroke volume and continues to perform the alternating pumping sequence just described until a desired or prescribed amount of fresh or used PD fluid is delivered to the destination. For any of the above primary embodiments, it should be appreciated that the delivery pressure may be higher, e.g., up to 8psig, for fresh or used PD fluid destinations (e.g., heater bags or drains) that do not involve the patient. It is also contemplated that for any of the primary embodiments, when the pneumatic cylinder or pump is removing spent PD fluid from the patient, the control unit monitors the associated first or second pressure sensor so that the patient discharge negative pressure limit, e.g., -1.5psig, is not met or exceeded.

It will be appreciated that the drift effects in the pneumatic pressure sensor used in the above embodiments are counteracted in that an important aspect of the cylinder sequence described above is that the initial and final pressures associated with fresh or used PD fluid delivery are equal, rather than the pressures being accurate from an absolute point of view (except for patient pressure limits). Moreover, because the system is pressure controlled, the linear actuator need not be highly accurate.

In accordance with the disclosure set forth herein, and without limiting the disclosure in any way, in a first aspect of the disclosure that may be combined with any other aspect or portion thereof, a peritoneal dialysis system includes a pneumatic pump chamber, a cylinder, a piston including a piston head slidably sealed within the cylinder, the piston head separating a first cylinder chamber from a second cylinder chamber, a linear actuator in mechanical communication with the piston, a first pneumatic line extending between the first cylinder chamber and the pneumatic pump chamber, a second pneumatic line extending between the second cylinder chamber and the pneumatic pump chamber, a first pneumatic valve positioned along the first pneumatic line, a second pneumatic valve positioned along the second pneumatic line, a pressure sensor positioned and arranged to measure pressure in the pneumatic pump chamber, a fluid pump chamber in operable communication with the pneumatic source, a control unit that extends between the first cylinder chamber and the pneumatic pump chamber, a second pneumatic valve positioned and arranged to cause the pneumatic pump chamber to move a pneumatic valve, a pneumatic valve is further configured to move the first pneumatic valve along the first pneumatic line, a second pneumatic valve positioned along the second pneumatic line, a piston head is positioned and arranged to measure pressure in the pneumatic pump chamber, a fluid pump chamber is further opened, the fluid pump chamber is opened, and the pneumatic valve is moved to the pneumatic pump chamber is moved by a control unit, in order to push a source fluid through the destination fluid valve, and wherein the control unit uses the output from the pressure sensor to control the linear actuator such that a final pressure for (ii) is at least substantially equal to an initial pressure for (ii) such that a volume of space corresponding to movement of the piston head within the cylinder during (ii) is equal to a volume of source fluid delivered from the fluid pump chamber during (ii).

In a second aspect of the disclosure, which may be combined with any of the other aspects or portions thereof, the source fluid valve is for a PD fluid supply vessel, a heating vessel, or a patient line.

In a third aspect of the present disclosure, which may be combined with any of the other aspects or portions thereof, the destination fluid valve is used to heat a container, an evacuation container, or a patient line.

In a fourth aspect of the present disclosure, which may be combined with any other aspect or portion thereof, a volume of the space corresponding to movement of the piston head within the cylinder varies with a distance the piston head moves within the cylinder and a cross-sectional area of an inner diameter of the cylinder.

In a fifth aspect of the present disclosure, which may be combined with any other aspect or portion thereof, the control unit is configured to determine a volume of source fluid delivered from the fluid pump chamber during (ii) with both the source fluid valve and the destination fluid valve closed.

In a sixth aspect of the disclosure, which may be combined with any other aspect or portion thereof, the control unit is further configured to, with the first pneumatic valve and the destination fluid valve closed, (iii) cause the second pneumatic valve and the source fluid valve to open to allow a negative pneumatic pressure in the second cylinder chamber generated during at least one of (i) or (ii) to reach the pneumatic pump chamber, thereby pulling a source fluid into the fluid pump chamber.

In a seventh aspect of the disclosure that may be combined with any other aspect or portion thereof, the control unit is further configured to (iv) cause the linear actuator to move the piston head into the second cylinder chamber with the first pneumatic valve, the source fluid valve, and the destination fluid valve closed, and the second pneumatic valve closed, so as to generate at least substantially zero pressure in the first cylinder chamber and the second cylinder chamber.

In an eighth aspect of the disclosure, which may be combined with any other aspect or portion thereof, the control unit is further configured to (v) cause the second pneumatic valve and the destination fluid valve to open and cause the linear actuator to move the piston head into the second cylinder chamber so as to push a source fluid through the destination fluid valve, and wherein the control unit uses the output from the pressure sensor to control the linear actuator such that a final pressure for (v) is at least substantially equal to an initial pressure for (v) such that a volume of a space corresponding to movement of the piston head within the cylinder during (v) is equal to a volume of source fluid delivered from a fluid pump chamber during (v).

In a ninth aspect of the disclosure that may be combined with any other aspect or portion thereof, the control unit is further configured to (vi) with the second pneumatic valve and the destination fluid valve closed, open the first pneumatic valve and the source fluid valve to allow negative pneumatic pressure in the first cylinder chamber generated during (v) to reach the pneumatic pump chamber, thereby pulling a source fluid into the fluid pump chamber.

In a tenth aspect of the present disclosure, which may be combined with any other aspect or portion thereof, a peritoneal dialysis system includes a pneumatic pump chamber, a cylinder, a piston including a piston head slidably sealed within the cylinder, a linear actuator in mechanical communication with the piston, an air pump, a first pneumatic line extending between the cylinder and the pneumatic pump chamber, a second pneumatic line extending between the air pump and the pneumatic pump chamber, a first pneumatic valve positioned along the first pneumatic line, a second pneumatic valve positioned along the second pneumatic line, a pressure sensor positioned and arranged to measure the pressure in the pneumatic pump chamber, a fluid pump chamber operatively coupled to the pneumatic pump, a fluid valve, a destination fluid valve, and a control unit configured to (i) cause the second pneumatic valve and the air pump to open and cause the pneumatic pump to open, thereby causing the pneumatic valve to open, and (ii) cause the pneumatic valve to be opened and the pneumatic pump to cause the pneumatic valve to be closed, wherein a pressure sensor is positioned and arranged to measure the pressure in the pneumatic pump chamber, a source fluid pump is operatively coupled to the pump chamber, a destination fluid valve is configured to be provided, and a control unit is configured to (i) cause the second pneumatic valve and the air pump to be opened, thereby causing the pneumatic valve to be opened and the pneumatic pump head to be opened, wherein a pressure sensor is caused to be opened and a pressure sensor is caused to be moved in the pneumatic pump chamber, the control unit uses the output from the pressure sensor to control the linear actuator such that the final pressure for (iii) is at least substantially equal to the initial pressure for (iii) such that the volume of space corresponding to movement of the piston head within the cylinder during (iii) is equal to the volume of source fluid delivered from the fluid pump chamber during (iii).

In an eleventh aspect of the present disclosure, which may be combined with any of the other aspects or portions thereof, the source fluid valve is for a PD fluid supply vessel, a heating vessel, or a patient line.

In a twelfth aspect of the present disclosure, which may be combined with any of the other aspects or portions thereof, the destination fluid valve is used to heat a container, an evacuation container, or a patient line.

In a thirteenth aspect of the present disclosure, which may be combined with any other aspect or portion thereof, a volume of the space corresponding to movement of the piston head within the cylinder varies with a distance the piston head moves within the cylinder and a cross-sectional area of an inner diameter of the cylinder.

In a fourteenth aspect of the present disclosure, which may be combined with any of the other aspects or portions thereof, the first pneumatic valve is opened during (i).

In a fifteenth aspect of the present disclosure, which may be combined with any other aspect or portion thereof, the control unit is further configured to (iv) cause the linear actuator to move the piston head within the cylinder in an opposite direction with the first pneumatic valve and the source fluid valve open, thereby pulling a source fluid into the fluid pump chamber.

In a sixteenth aspect of the present disclosure, which may be combined with any other aspect or portion thereof, during (iv) the first pneumatic valve is opened and the air pump is actuated to assist in pulling a source of fluid into the fluid pump chamber.

In a seventeenth aspect of the present disclosure, which may be combined with any of the other aspects or portions thereof, a peritoneal dialysis system includes a first pneumatic pump chamber; a second pneumatic pump chamber; a cylinder; A piston comprising a piston head slidably sealed within the cylinder, a linear actuator in mechanical communication with the piston, an air pump, a first pneumatic line extending between the cylinder and the first pneumatic pump chamber, a second pneumatic line extending between the cylinder and the second pneumatic pump chamber, a third pneumatic line extending between the air pump and the first pneumatic pump chamber, a fourth pneumatic line extending between the air pump and the second pneumatic pump chamber, a first pneumatic valve positioned along the first pneumatic line, a second pneumatic valve positioned along the second pneumatic line, a third pneumatic valve positioned along the third pneumatic line, a fourth pneumatic valve positioned along the fourth pneumatic line, a first pneumatic valve positioned in the first pneumatic pump chamber and a first pneumatic pump chamber, a first pneumatic valve positioned in the first pneumatic pump, a first pneumatic valve positioned in the first pneumatic pump, and a first pneumatic valve positioned in the first pneumatic valve, and a first pneumatic valve, positioned in the first valve, and a first valve, is positioned, and a first valve, and, is positioned, and, and, the second fluid pump chamber is operably coupled with the first pneumatic pump chamber, a second source fluid valve for the second pump chamber, a second destination fluid valve for the second pump chamber, and a control unit configured to generate negative and positive pneumatic pressures in the first and second pneumatic pump chambers using the air pump and to actuate the linear actuator to move the piston head within the cylinder while equalizing initial and final positive pneumatic pressures to meter determinable volumes of source fluid through the first and second destination fluid valves.

In an eighteenth aspect of the disclosure, which may be combined with any other aspect or portion thereof, the control unit is configured to (i) with the third pneumatic valve and the first source fluid valve open, cause the air pump to generate a negative pneumatic pressure in the first pneumatic pump chamber to pull source fluid into the first fluid pump chamber, (ii) with the third pneumatic valve open and the first source fluid valve closed, cause the air pump to generate a desired positive pneumatic pressure in the first pneumatic pump chamber measured by the first pressure sensor, and (iii) with the first pneumatic valve and the first destination fluid valve open, cause the linear actuator to move the piston head within the cylinder to push source fluid through the first destination fluid valve, and wherein the control unit uses output from the first pressure sensor to control the linear actuator such that a final pressure for (iii) is at least substantially equal to an initial pressure for (iii) during which the second pneumatic pump chamber is to generate a negative pneumatic pressure corresponding to the second source fluid flow in the first pump chamber and the second pneumatic pump chamber.

In a nineteenth aspect of the present disclosure, which may be combined with any other aspect or portion thereof, the control unit is further configured to cause (iv) with the fourth pneumatic valve open and the second source fluid valve closed, the air pump to generate a desired positive pneumatic pressure in the second pneumatic pump chamber measured by the first pressure sensor, and (v) with the second pneumatic valve and the second destination fluid valve open, the linear actuator to move the piston head within the cylinder so as to push a source fluid through the second destination fluid valve, and wherein the control unit uses output from the second pressure sensor to control the linear actuator so that a final pressure for (v) is at least substantially equal to an initial pressure for (v) so that a volume of a space corresponding to movement of the piston head within the cylinder during (v) is equal to a volume of fluid delivered from the second pneumatic valve and the second pneumatic valve during (v) and to generate a negative pneumatic pressure in the pump chamber so as to pull a source fluid through the second pneumatic valve.

In a twentieth aspect of the present disclosure, which may be combined with any of the other aspects or portions thereof, a peritoneal dialysis system includes a first pneumatic pump chamber; a second pneumatic pump chamber; the system includes a cylinder, a piston including a piston head slidably sealed within the cylinder, the piston head separating a first cylinder chamber from a second cylinder chamber, a linear actuator in mechanical communication with the piston, an air pump, a first pneumatic line extending between the second cylinder chamber and the first pneumatic pump chamber, a second pneumatic line extending between the second cylinder chamber and the second pneumatic pump chamber, a third pneumatic line extending between the air pump and the first pneumatic pump chamber, a fourth pneumatic line extending between the air pump and the second pneumatic pump chamber, a fifth pneumatic line extending between the first cylinder chamber and the first pneumatic line, a first pneumatic valve positioned along the first pneumatic line, a second pneumatic valve positioned along the second pneumatic line, a third pneumatic valve positioned along the third pneumatic line, a fourth pneumatic valve positioned along the second pneumatic line, a fifth pneumatic valve positioned along the fourth pneumatic pump chamber, a fifth pneumatic valve positioned along the fourth pneumatic pump chamber, the second pressure sensor is positioned and arranged to measure pressure in the second pneumatic pump chamber, a first fluid pump chamber operatively coupled with the first pneumatic pump chamber, a first source fluid valve for the first pump chamber, a first destination fluid valve for the first pump chamber, a second fluid pump chamber operatively coupled with the first pneumatic pump chamber, a second source fluid valve for the second pump chamber, a second destination fluid valve for the second pump chamber, and a control unit configured to use the air pump to generate negative and positive pneumatic pressures in the first and second pneumatic pump chambers and to actuate the linear actuator to move the piston head within the first and second cylinder chambers while simultaneously enabling final and positive pneumatic pressures to be equal by the first and second destination fluid valves.

In a twenty-first aspect of the disclosure, which may be combined with any other aspect or portion thereof, the control unit is configured such that (i) with the third pneumatic valve and the first source fluid valve open, the air pump generates a negative pneumatic pressure in the first pneumatic pump chamber, pulling a source fluid into the first fluid pump chamber, and with the second pneumatic valve and the fifth pneumatic valve and the second destination fluid valve open, the linear actuator moves the piston head toward the first cylinder chamber to push a source fluid through the second destination fluid valve, and wherein the control unit uses an output from the second pressure sensor to control the linear actuator such that a final pressure for (i) is at least substantially equal to an initial pressure for (i) such that a volume of a space corresponding to movement of the piston head toward the first cylinder chamber during (i) is equal to a volume of the source fluid delivered from the second fluid pump chamber during (i).

In a twenty-second aspect of the disclosure, which may be combined with any other aspect or portion thereof, the control unit is further configured such that (ii) with the fourth pneumatic valve and the second source fluid valve open, the air pump generates a negative pneumatic pressure in the second pneumatic pump chamber, pulling a source fluid into the second fluid pump chamber, and with the first pneumatic valve and the sixth pneumatic valve and the first destination fluid valve open, the linear actuator moves the piston head toward the second cylinder chamber to push a source fluid through the first destination fluid valve, and wherein the control unit uses an output from the first pressure sensor to control the linear actuator such that a final pressure for (ii) is at least substantially equal to an initial pressure for (ii) such that a volume of a space corresponding to movement of the piston head toward the second cylinder chamber during (ii) is equal to a volume of fluid delivered from the second fluid pump chamber during (ii).

In a twenty-third aspect, which may be combined with any other aspect or portion thereof, any features, functions, and alternatives described in connection with any one or more of the figures 1-28 may be combined with any features, functions, and alternatives described in connection with any other of the figures 1-28.

Accordingly, it is an advantage of the present disclosure to provide an automated peritoneal dialysis ("PD") machine that is relatively accurate in volume.

Another advantage of the present disclosure is to provide a PD machine that achieves relatively accurate pressure control.

Another advantage of the present disclosure is to provide a relatively quiet PD machine.

Yet another advantage of the present disclosure is to provide a PD machine that is accurate regardless of how the pressure sensor drifts with time, temperature, humidity, etc.

Yet another advantage of the present disclosure is to provide a PD machine that eliminates the dependence of volumetric accuracy on absolute pressure sensing.

Yet another advantage of the present disclosure is to provide a PD system that uses low cost and simple machinery and low cost and simple disposables.

Additional features and advantages are described in, and will be apparent from, the following detailed description and the accompanying drawings. The features and advantages described herein are not all inclusive and, in particular, many additional features and advantages will be apparent to one of ordinary skill in the art in view of the drawings and description. Moreover, any particular embodiment need not have all of the advantages listed herein, and it is expressly contemplated that each advantageous embodiment is separately claimed. Furthermore, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and may not have been selected to delineate the scope of the presently disclosed subject matter.

Drawings

Fig. 1 is a schematic elevation view of one embodiment of a peritoneal dialysis ("PD") system of the present disclosure.

Fig. 2 and 3 are schematic diagrams of a first main embodiment of the PD system of the present disclosure, which uses a cylinder.

Fig. 4 to 13 are schematic diagrams of a second main embodiment of the PD system of the present disclosure, which uses a cylinder.

Fig. 14 to 20 are schematic diagrams of a third main embodiment of the PD system of the present disclosure, which uses a cylinder and an air pump.

Fig. 21 to 24 are schematic diagrams of a fourth main embodiment of the PD system of the present disclosure, which uses a cylinder and an air pump.

Fig. 25 to 28 are schematic diagrams of a fifth main embodiment of the PD system of the present disclosure, which uses a cylinder and an air pump.

Detailed Description

Referring now to the drawings, and in particular to FIG. 1, an automated peritoneal dialysis ("PD") system 10 includes a PD machine or cycler 20 that operates with a disposable set 110. The disposable set 110 includes or defines at least one fluid pump chamber 112a, 112b, which may include two flexible sheets welded together to form a circular chamber that may be deployed in a spherical fashion, for example. The at least one fluid pump chamber 112a, 112b may alternatively comprise a single flexible sheet welded to a rigid hemispherical pump housing. All welds discussed herein may be achieved by heat sealing, ultrasonic sealing, or solvent bonding.

The disposable set 110 also includes or defines a plurality of fresh and used PD fluid lines, such as a heater line 114a, a drain line 114b, PD fluid supply lines 114c, 114d, 114e, a patient line 114f, and a fluid pump chamber line 114g. Fresh and used PD fluid lines may be formed via tubing, via a welded path between two flexible sheets, or via a molded path in a rigid cassette.

The disposable set 110 also includes a plurality of PD fluid receptacles, such as a heating receptacle 116a, a discharge receptacle 116b, and PD fluid supply receptacles 116c, 116d, and 116e. The heating reservoir 116a in the illustrated embodiment is located on a heating tray at the top of the housing 22 of the PD machine or circulator 20. A bulk heater 24, such as a resistive heater, is provided at the top of the PD machine or circulator 20 under the control of the control unit 100. In an alternative embodiment, an initial one of the supply containers 116c, 116d, and 116e is placed on a heating tray and then used as a heating container for the rest of the process once emptied. In another alternative embodiment, the heater 24 is instead an in-line heater that operates with the patient line 114f, for example, so that the heating vessel 116a may be eliminated. In any event, the control unit 100 is programmed to cause the heater 24 to heat fresh PD fluid to the patient temperature, e.g., 37 ℃.

Any desired number and size of PD fluid supply containers 116c, 116d, 116e may be provided, and these PD fluid supply containers may hold PD fluids of the same or different dextrose or glucose levels. One of the PD fluid supply containers 116c, 116d, 116e may be a last filled container and contain a different PD formulation, such as icodextrin. Additionally, the drain line 114b may instead lead to a house drain, such as a toilet or bathtub, in which case the drain reservoir 116b is not required. Any of the containers 116 a-116 a may be formed as flexible containers or bags.

The disposable set 110 in the illustrated embodiment also includes a plurality of fluid valve seats, such as a heater valve seat 118a, a drain valve seat 118b, PD fluid supply valve seats 118c, 118d, 118e, a patient valve seat 118f, and a fluid pump chamber valve seat 118g. The fluid valve seats 118 a-118 g may be tubing locations formed by welding two flexible sheets or by molding in a rigid box. The fluid valve seats 118 a-118 g operate with a valve actuator (not shown in fig. 1), which may be a magnetically actuated solenoid pinch valve actuator, an electric pinch valve, or a pneumatically actuated valve actuator.

In the system 10, and as described in detail below, the supply vessels 116c, 116d, and 116e are fresh PD fluid sources (("FS"), although one supply vessel may be a fresh PD fluid destination if used as a heating vessel. The drain reservoir 116b is a used PD fluid destination ("FD"). Heating vessel 116a is a fresh PD fluid source ("FS") and a fresh PD fluid destination ("FD"). Patient line 114f (patient) is a source of used PD fluid ("FS") and a destination of fresh PD fluid ("FD").

In the system 10, and as described in detail below, the PD fluid supply valve seats 118c, 118d, and 118e are source fluid valves ("SV"), although may be destination fluid valves ("DV") if used as heater valves. The exhaust valve seat 118b is a destination fluid valve ("DV"). The heater valve seat 118a and the patient valve seat are a source fluid valve ("SV") and a destination fluid valve ("DV"). The fluid pump chamber valve seat 118g allows the fluid pump chambers 112a, 112b to alternately draw fresh or used PD fluid or pump fresh or used PD fluid according to a current pumping sequence such that the flow of a desired destination is relatively continuous.

Any rigid component of the disposable set 110 may be made of plastic, such as polyvinyl chloride ("PVC"), polyethylene ("PE"), polyurethane ("PU"), or polycarbonate ("PC"). Any flexible components of the disposable set 110 (such as the membranes or diaphragms, tubing, and containers discussed herein) may be made of medically safe materials, such as one or more plastics, e.g., PVC, PE, PU or other suitable non-PVC polymers. The rigid pump housing 22, the cylinders discussed herein and their associated components, the pneumatic lines discussed herein are reusable in one embodiment and may be made of plastic (such as polyvinyl chloride ("PVC"), polyethylene ("PE"), or polyurethane ("PU")) or metal (such as stainless steel or aluminum), and combinations thereof.

First main embodiment

In a first main embodiment of the system 10 as shown in fig. 2 and 3, a cylinder 30 is provided. The air cylinder 30 is located between the first and second pneumatic pump chambers 70a, 70b, which first and second pneumatic pump chambers 70a, 70b operate with the fluid pump chambers 112a, 112b, respectively, of the disposable set 110. A piston 32 is located within the cylinder 30, wherein the piston 32 includes a piston shaft 34 and a piston head 36 separating the cylinder 30 into a first cylinder chamber 30a and a second cylinder chamber 30 b. The piston shaft 34 and piston head 36 in the illustrated embodiment are driven by a linear actuator 40. The linear actuator 40 may include a motor, such as a stepper motor that drives rotation to a translation conversion device, such as a lead screw or a ball screw. The linear actuator 40 may alternatively be pneumatically driven. In any event, the piston shaft 34 is coupled to a linear actuator 40 external to the cylinder 30 for translating the piston shaft and piston head 36 within the cylinder.

First pneumatic line 42a extends from first cylinder chamber 30a to first pneumatic pump chamber 70a. A second pneumatic line 42b extends from the second cylinder chamber 30b to a second pneumatic pump chamber 70b. First pressure sensor 44a is positioned to read the air pressure in first pneumatic line 42a, first pneumatic pump chamber 70a, and first cylinder chamber 30 a. The second pressure sensor 44b is positioned to read the air pressure in the second pneumatic line 42b, the second pneumatic pump chamber 70b, and the second cylinder chamber 30 b.

First exhaust line 46a and associated first exhaust valve 48a are optionally placed in fluid communication with first cylinder chamber 30 a. A second exhaust line 46b and an associated second exhaust valve 48b are optionally placed in fluid communication with second cylinder chamber 30 b.

All of the fluid valve actuators (driving the fluid valve seats 118 a-118 g), motors or other drivers of the linear actuator 40, the PD fluid heater 24, and other controllable electrical devices are under the control of the control unit 100, the control unit 100 includes at least one processor 102, at least one memory 104, and a video controller 106 for controlling a user interface 108 (which may be coupled to the cycle machine 20 as shown or a wireless user interface). The control unit may also be configured to receive signals from all sensors, such as all pneumatic pressure sensors (e.g., 44a, 44 b), fluid pressure sensors (if provided), motor encoders (or other position determining mechanisms for the linear actuator 40), and any temperature sensors associated with the heater 24. The control unit 100 may also include a transceiver (not shown) and a wired or wireless connection to a network (e.g., the internet) for sending treatment data to and receiving prescription instructions from a doctor or physician's server interacting with the doctor or physician's computer. The user interface 108 may include a display screen that operates with a touch screen and/or one or more electromechanical buttons (such as membrane switches). The user interface 108 may also include one or more speakers for outputting alerts, warnings, and/or voice-guided commands.

To achieve the desired fresh or used PD fluid pumping sequence described herein, the control unit 100 may feed the difference between the commanded pressure and the pressure measured at the associated pressure sensor (e.g., pressure sensor 44a, 44 b) into a control algorithm (e.g., a proportional, integral, derivative ("PID") algorithm) that attempts to reduce the difference between the commanded pressure and the measured pressure to zero, and this produces an output to the electronic motor driver in one example of the linear actuator 40. In each of the main embodiments of the system 10 described herein, the control algorithm analysis is performed at some periodic frequency. The control unit 100 is programmed to run all of the pumping sequences discussed herein, including the sequence of the first main embodiment discussed next.

As shown in fig. 2 and 3, the PD machine or circulator 20 operates a disposable set 110. The disposable set 110 includes, among other things, a first fluid pump chamber 112a and a second fluid pump chamber 112b that operate with the first pneumatic pump chamber 70a and the second pneumatic pump chamber 70b, respectively. When the piston head 36 moves to generate a negative pneumatic pressure within the first or second cylinder chambers 30a, 30b, a corresponding negative pressure is generated in the respective first or second pneumatic pump chambers 70a, 70 b. The negative pressure created in the first or second pneumatic pump chamber 70a, 70b in turn pulls the flexible membrane of the corresponding first or second fluid pump chamber 112a, 112b into the first or second pneumatic pump chamber 70a, 70b, such that the fluid pump chamber is filled with fresh or used PD fluid. When the piston head 36 moves to generate positive pneumatic pressure within the first or second cylinder chambers 30a, 30b, a corresponding positive pressure is generated in the respective first or second pneumatic pump chambers 70a, 70 b. The positive pressure created in the first or second pneumatic pump chambers 70a, 70b in turn pushes against the flexible membrane of the corresponding first or second fluid pump chamber 112a, 112b, causing the fluid pump chambers 112a, 112b to close and expel fresh or used PD fluid.

The control unit 100 in the first main embodiment causes the piston shaft 34 to translate the piston head 36 back and forth within the cylinder 30 such that in one half stroke (i), the first fluid pump chamber 112a is filled with fresh or used PD fluid while the second fluid pump chamber 112b is discharging fresh or used PD fluid. In the second half stroke (ii), the second pump chamber 112b is filled with fresh or used PD fluid while the first fluid pump chamber 112a is discharging fresh or used PD fluid. The control unit 100 translates the piston head 36 back and forth in the manner described above until a desired or prescribed volume of fresh or used PD fluid is delivered from a desired PD fluid source to a desired PD fluid destination. Fluid valves are provided and sequentially actuated by the control unit 100 to access a desired fluid source and a desired fluid destination. The fluid valve again may comprise a magnetically actuated solenoid valve, an electrically actuated pinch valve or a pneumatically actuated valve.

In the first primary embodiment, and in the event that patient pumping is occurring such that pressure control is important, the control unit 100 monitors the output from the first and second pressure sensors 44a, 44b while the piston head 36 translates back and forth. The control unit 100 controls the speed of the back and forth translation so that the desired safe negative or positive fluid pumping pressure (e.g., -1.5 psig (pounds force per square inch), 1.5 psig to 3.0 psig) is not exceeded.

In the first primary embodiment, the amount of fresh or used PD fluid delivered to the destination is determined by maintaining a constant pressure before and after movement of the piston head 36, which counteracts the compressibility effect of the air in the cylinder 30. Since the post-movement pressure (P2) is equal to the pre-movement pressure (P1), the volume of air in the cylinder 30 remains constant. Thus, the volume displaced by the piston head 36 is equal to the volume of fluid being delivered.

Second main embodiment

Fig. 4-13 illustrate a second main embodiment of the system 10, wherein only the air cylinder 30 is provided as previously described, but wherein the air cylinder is dedicated to a single air pump chamber 70a, 70 b/fluid pump chamber 112a, 112b pair. Two pneumatic pump chamber/fluid pump chamber pairs (pairs 70a, 112a are shown by way of example) may be provided, with each pair having its own dedicated cylinder 30. The cylinder 30 is constructed as in the first primary embodiment, including a piston 32 having a piston head 36 and a piston shaft 34 driven by a linear actuator 40. Optional exhaust lines 46a, 46b and pneumatic exhaust valves 48a, 48b may be in pneumatic communication with the first and second chambers 30a, 30b of each cylinder 30.

In the second main embodiment, the first pneumatic line 56a and the second pneumatic line 56b extend from the first cylinder chamber 30a and the second cylinder chamber 30b, respectively, to the same pneumatic pump chamber 70a. First and second pneumatic valves 58a and 58b under the control of the control unit 100 are provided along the first and second pneumatic lines 56a and 56 b. One or more pressure sensors 44a are disposed along a common portion of the first pneumatic line 56a and the second pneumatic line 56b or along each of the first pneumatic line and the second pneumatic line. The fluid pump chambers 112a, 112b are again provided as part of the disposable set 110, wherein the fluid pump chamber 112a pumps fresh or used PD fluid from a desired PD fluid source FS to a desired destination FD, as determined by the sequence of fluid source valves SV and fluid destination valves DV.

Fig. 4 shows that the control unit 100 in the second main embodiment causes the piston shaft 34 to translate the piston head 36 toward the first cylinder chamber 30a, thereby generating positive pressure in the first cylinder chamber 30a and negative pressure in the second cylinder chamber 30 b. The control unit 100 also causes the source fluid valve SV and the second pneumatic valve 58b to open, allowing negative pressure to reach the pneumatic pump chamber 70a, and causes the flexible membrane of the fluid pump chamber 112a to be pulled into the pneumatic pump chamber 70a and filled with fresh or used PD fluid.

Fig. 5 shows that control unit 100 then closes source fluid valve SV and second pneumatic valve 58b and opens first pneumatic valve 58a so that pressure sensor 44a can read the positive pressure in first cylinder chamber 30 a. The control unit 100 also moves the piston 32 into the first cylinder chamber 30a such that the positive pressure in the pneumatic pump chamber 70a reads a desired pressure, e.g., 1.5psig, to pump fresh or used PD fluid to the desired destination FD. At the end of this movement, the piston head 36 is in the initial piston head position.

Fig. 6 shows that the control unit 100 maintains the first air valve 58a in an open state and opens the destination fluid valve DV. The desired positive pressure built into the pneumatic pump chamber 70a forces the flexible membrane of the fluid pump chamber 112a to collapse and push fresh or used PD fluid to the desired destination FD. As the positive pressure dissipates, control unit 100 moves piston 32 further into first cylinder chamber 30a such that pressure sensor 44a continues to read the desired pressure, e.g., 1.5psig.

Fig. 7 shows that eventually the flexible membrane cannot collapse further, resulting in a peak reading at the pressure sensor 44a, at which point the control unit 100 stops the pump-out translation of the piston head 36 and closes the destination fluid valve DV. Alternatively or additionally, detection that the flexible membrane cannot collapse further may be determined by the control unit 100 detecting that the linear actuator 40 and/or piston head 36 are not moving while maintaining a desired pressure (e.g., 1.5 psig). In any event, after stopping the pump-out translation, first pneumatic valve 58a remains open to allow the positive pressure that has been maintained at the desired pressure to equilibrate between first cylinder chamber 30a and pneumatic pump chamber 70a, and this positive pressure may be read by pressure sensor 44 a. The piston head 36 is now in the final piston head position. The volume difference between the cylinder 30 at the known cross-sectional area between the final piston head position and the initial piston head position is the volume of fresh or used PD fluid pumped to the desired destination FD as determined by the control unit 100 due to the same pressure at the initial piston head position and the final piston head position (e.g., 1.5psig, which is the desired pump-to-patient pressure, for example). That is, the volume of space corresponding to movement of the piston head 36 within the cylinder 30 varies with the distance the piston head moves within the cylinder and the cross-sectional area of the cylinder bore (which is substantially the same as the circular area of the piston head 36).

Fig. 8 shows that, next, with the second cylinder chamber 30b still under negative pressure (which is not critical if pulled from a non-patient source), the control unit 100 opens the source fluid valve SV and the second pneumatic valve 58b, allowing negative pressure to reach the pneumatic pump chamber 70a and causing the flexible membrane of the fluid pump chamber 112a to be pulled into the pneumatic pump chamber 70a and filled with fresh or used PD fluid.

Fig. 9 shows that, next, the control unit 100 closes the source fluid valve SV but allows the second pneumatic valve 58b to remain open so that the pneumatic pump chamber 70a and the second cylinder chamber 30b remain exposed to the pressure sensor 44a. Control unit 100 translates piston 32 into second cylinder chamber 30b until pressure sensor 44a reads zero psig. The pressure in first chamber 30a should also be near zero psig.

Fig. 10 shows that next, with source fluid valve SV and destination fluid valve DV closed, first pneumatic valve 58a closed and second pneumatic valve 58b open so that pressure sensor 44a can read the positive pressure in second cylinder chamber 30b, control unit 100 moves piston 32 into second cylinder chamber 30b so that the positive pressure in pneumatic pump chamber 70a again reads the desired pressure, e.g., 1.5psig, to pump fresh or used PD fluid to the desired destination FD. At the end of this movement, the piston head 36 is again in the initial piston head position.

Fig. 11 shows that, next, the control unit 100 maintains the second air-operated valve 58b in the open state, and opens the destination fluid valve DV. The desired positive pressure built up in the pneumatic pump chamber 70a again forces the flexible membrane of the fluid pump chamber 112a to collapse and push fresh or used PD fluid to the desired destination FD. As the positive pressure dissipates, control unit 100 moves piston 32 further into second cylinder chamber 30b so that pressure sensor 44a continues to read the desired pressure, e.g., 1.5psig.

Fig. 12 shows that eventually the flexible membrane cannot collapse further, resulting in a peak reading at the pressure sensor 44a, at which point the control unit 100 stops the pump-out translation of the piston head 36 and closes the destination fluid valve DV. Alternatively or additionally, detection that the flexible membrane cannot collapse further may again be determined by the control unit 100 detecting that the linear actuator 40 and/or piston head 36 are not moving while maintaining a desired pressure (e.g., 1.5 psig). In any event, after stopping the pump-out translation, second pneumatic valve 58b remains open to allow the positive pressure that has been maintained at the desired pressure to equilibrate between first cylinder chamber 30a and pneumatic pump chamber 70a, and this positive pressure may be read by pressure sensor 44 a. The piston head 36 is now in the final piston head position. The volume difference of cylinder 30 at the known cross-sectional area between the final and initial piston head positions is again the volume of fresh or used PD fluid calculated by control unit 100 to pump to the desired destination DV due to the same pressure at the initial and final piston head positions (e.g., 1.5psig, which is the desired pump-to-patient pressure).

Fig. 13 shows that with the first cylinder chamber 30a still under negative pressure (which is not critical if pulled from a non-patient source), the control unit 100 opens the source fluid valve SV and the first pneumatic valve 58a, allowing negative pressure to reach the pneumatic pump chamber 70a and causing the flexible membrane of the fluid pump chamber 112a to be pulled into the pneumatic pump chamber 70a and filled with fresh or used PD fluid. The above process is repeated until the desired amount of fresh or used PD fluid is delivered to the desired destination FD. It should be appreciated that the above-described process may be used with any fresh or used PD fluid source FS and any fresh or used PD fluid destination FD described herein, and that suction pressure and delivery pressure, as well as delivered PD fluid volume, may be controlled and measured, respectively.

Third main embodiment

Fig. 14-20 illustrate a third main embodiment of the system 10 incorporating an air pump 80 that operates in cooperation with the air cylinder 30. The air pump may generally transition more quickly between a positive pumping pressure and a negative pumping pressure and vice versa. Moreover, even a small air pump can generate a wide range of pressure. These two advantages of the air pump 80 are combined with the ability of the air cylinder 30 to meter a known volume of fluid under pressure control as described herein.

The structure of the cylinder 30 in the third main embodiment is substantially the same as in the first and second main embodiments, and includes a piston head 36 and a piston shaft 34 driven by a linear actuator 40. An optional exhaust line 46a, 46b and a pneumatic exhaust valve 48a, 48b may be in pneumatic communication with the first cylinder chamber 30a and the second cylinder chamber 30b, respectively, of each cylinder 30. In the third main embodiment, only the first pneumatic line 56a extends from the cylinder 30 to the pneumatic pump chamber 70a. A first pneumatic valve 58b under the control of the control unit 100 is provided along the first pneumatic line 56 a. The second pneumatic line 56c extends from the air pump 80 and intersects the first pneumatic line 56 a. A second pneumatic valve 58v under the control of the control unit 100 is provided along the second pneumatic line 58 c. The pressure sensor 44a is disposed along a common portion of the first pneumatic line 56a and the second pneumatic line 56 c. One or more fluid pump chambers 112a, 112b (here, the chamber 112a is shown by way of example only) are again provided as part of the disposable set 10, wherein the fluid pump chamber 112a pumps fresh or used PD fluid from a desired PD fluid source FS to a desired destination FD, as determined by the sequence of one or more fluid valves SV, DV.

Fig. 14 shows that the control unit 100 in the third main embodiment initially opens the first and second pneumatic valves 58a and 58c, opens the source fluid valve SV, and causes the air pump 80 to create a negative pressure in the pneumatic pump chamber 70a and the cylinder chamber 30a, thereby pulling the flexible membrane of the fluid pump chamber 112a into the pneumatic pump chamber 70a and pulling fresh or used PD fluid into the fluid pump chamber 112 a. In an embodiment, the control unit 100 monitors the speed of the air pump 80 during the PD fluid extraction phase. When the speed of the air pump 80 begins to decrease beyond the set threshold, the control unit 100 determines that the flexible membrane is fully pulled and inflated, and thus the fluid pump chamber 112a is filled with fresh or used PD fluid. The speed of the air pump 80 is directly related to the flow rate of the PD fluid (e.g., how fast the PD fluid is loaded into the pump chamber 112 a). Thus, the control unit 100 may be programmed to monitor the speed of the air pump 80 to determine whether the film is fully stretched (e.g., stop the air pump after detecting a threshold speed change). In an embodiment, the control unit 100 also provides closed loop control to the air pump 80 such that the desired pressure is maintained. The control loop via the control unit 100 may be a proportional, integral, derivative ("PID") control loop that ensures that the pressure does not extend beyond a set threshold that may damage the membrane.

Fig. 15 shows that after fluid pump chamber 112a is completely filled with PD fluid, control unit 100 causes source fluid valve SV and first pneumatic valve 58a to close. Fig. 16 shows that control unit 100 then causes first pneumatic valve 58a and second pneumatic valve 58c to open and air pump 80 to generate the desired positive pumping pressure (e.g., 1.5 psig) in pneumatic pump chamber 70a and cylinder chamber 30 a. Fig. 17 shows that once the desired positive pumping pressure is reached, the control unit 100 closes the second pneumatic valve 58c so that the air pump 80 is isolated and blocked. The piston head 36 of the piston 32 is here in the initial piston head position.

Fig. 18 shows that, next, the control unit 100 maintains the first air-operated valve 58a in the open state and opens the destination fluid valve DV. The desired positive pressure built into pneumatic pumping chamber 70a forces the flexible membrane of fluid pumping chamber 112a to collapse and push fresh or used PD fluid to the desired fluid destination FD. As the positive pressure dissipates, control unit 100 moves piston 32 within cylinder chamber 30a such that pressure sensor 44a continues to read the desired pressure, e.g., 1.5psig.

Fig. 19 shows that eventually the flexible membrane of the fluid pump chamber 112a cannot collapse further, resulting in a peak reading at the pressure sensor 44a, at which point the control unit 100 stops the pump-out translation of the piston head 36 and closes the destination fluid valve DV. Alternatively or additionally, detection that the flexible membrane cannot collapse further may again be determined by the control unit 100 detecting that the linear actuator 40 and/or piston head 36 are not moving while maintaining a desired pressure (e.g., 1.5 psig). In any event, after stopping the pump-out translation, first pneumatic valve 58a remains open to allow the positive pressure that has been maintained at the desired pressure to equilibrate between cylinder chamber 30a and pneumatic pump chamber 70a, and this positive pressure may be read by pressure sensor 44 a. The piston head 36 is now in the final piston head position. The volume difference of cylinder 30 at the known cross-sectional area between the final piston head position and the initial piston head position is the volume of fresh PD fluid pumped by control unit 100 to the desired fluid destination FD due to the same pressure at the initial piston head position and the final piston head position (e.g., 1.5psig, which is the desired pump-to-patient pressure).

Fig. 20 shows that control unit 100 then opens first pneumatic valve 58a and second pneumatic valve 58c, opens source fluid valve SV, and moves piston 32 in the opposite direction within cylinder 30 to reposition piston head 36 for the next pump-out stroke. The movement of the piston 32 creates a negative pressure within the cylinder chamber 30a and the pneumatic pump chamber 70a, which may be assisted by the air pump 80 to quickly achieve a desired PD fluid extraction pressure. The flexible membrane of fluid pump chamber 112a is pulled into pneumatic pump chamber 70a and fresh or used PD fluid is correspondingly pulled into the fluid pump chamber. The above process of the third main embodiment is repeated, wherein the control unit 100 accumulates the pump stroke volume until a desired or prescribed amount of fresh or used PD fluid is delivered to the desired fluid destination FD.

Fourth main embodiment

Fig. 21-24 illustrate a fourth main embodiment of the system 10, which also uses an air pump 80, the air pump 80 cooperating with the air cylinder 30. Here, a single air pump 80 and air cylinder can drive two fluid pump chambers 112a, 112b within two pneumatic pump chambers 70a, 70b, respectively. The structure of the cylinder 30 in the fourth main embodiment is the same as that in the third main embodiment, and includes a piston head 36 and a piston shaft 34 driven by a linear actuator 40. An optional exhaust line and a pneumatic exhaust valve (not shown) may be in pneumatic communication with the first and second chambers of each cylinder. In the fourth main embodiment, only the first pneumatic line 56a extends from the cylinder 30, but the first pneumatic line 56 is bifurcated to further include a second pneumatic line 56b, wherein the first pneumatic line 56a and the second pneumatic line 56b extend to the first pneumatic pump chamber 112a and the second pneumatic pump chamber 112b, respectively. First and second pneumatic valves 58a and 58b under the control of the control unit 100 are disposed along the first and second pneumatic lines 56a and 56b, respectively.

The third pneumatic line 56c extends from the air pump 80 and diverges into the fourth pneumatic line 56d. The third pneumatic line 56c intersects the first pneumatic line 56a, and the fourth pneumatic line 56d intersects the second pneumatic line 56 b. The third pneumatic valve 58c under the control of the control unit 100 is disposed along the third pneumatic line 56c, and the fourth pneumatic valve 58d under the control of the control unit 100 is disposed along the fourth pneumatic line 56d. The first pressure sensor 44a is disposed adjacent the pneumatic pump chamber 70a, and the second pressure sensor 44b is disposed adjacent the pneumatic pump chamber 70 b. The first fluid pump chamber 112a and the second fluid pump chamber 112b are provided as part of the disposable set 100, wherein the first fluid pump chamber and the second fluid pump chamber pump fresh or used PD fluid from a desired PD fluid source FS to a desired PD fluid destination FD, as determined by the sequence of the plurality of fluid valves SV, DV.

In the pumping sequence of the fourth main embodiment, the first fluid pumping chamber 112a and the second fluid pumping chamber 112b are generally alternating, wherein when one fluid pumping chamber 112a or 112b draws fresh or used PD fluid, the other fluid pumping chamber 112b or 112a pushes fresh or used PD fluid out. Each fluid pump chamber 112a, 112b has its own set of source and destination valves SV, DV, however, complete synchronization of the first and second fluid pump chambers 112a, 112b is not required.

Fig. 21 shows that the control unit 100 in the fourth main embodiment initially opens the third pneumatic valve 58c and the source fluid valve SV for the first fluid pump chamber 112a and causes the air pump 80 to create a negative pressure in the first pneumatic pump chamber 70a, thereby pulling the flexible membrane of the first fluid pump chamber 112a into the first pneumatic pump chamber 70a and pulling fresh or used PD fluid into the first fluid pump chamber. During the PD fluid extraction phase, the control unit 100 may again monitor the speed of the air pump 80. When the speed of the air pump 80 begins to decrease beyond the threshold, the control unit 100 determines that the flexible membrane is fully pulled and inflated, and thus the fluid pump chamber 112a is full of fresh or used PD fluid, at which point the control unit 100 stops the air pump 80 and closes the source fluid valve SV for the first fluid pump chamber 112 a.

Fig. 22 shows that, next, the control unit 100 maintains the third pneumatic valve 58c in an open state and causes the air pump 80 to generate a desired positive pumping pressure (e.g., 1.5psig as read by the first pressure sensor 44 a) in the first pneumatic pump chamber 70 a. At this time, the piston head 36 of the piston 32 of the cylinder 30 is in the initial piston head position.

Fig. 23 shows that, next, the control unit 100 closes the third air-operated valve 58c, opens the first air-operated valve 58a, and opens the first destination fluid valve DV. The desired positive pressure built into the first pneumatic pump chamber 70a forces the flexible membrane of the first fluid pump chamber 112a to collapse and push fresh or used PD fluid to the desired fluid destination FD. As the positive pressure dissipates, control unit 100 moves piston 36 within cylinder chamber 30a such that first pressure sensor 44a continues to read the desired pressure, e.g., 1.5psig. At the same time (or near the same time), the control unit 100 causes the fourth pneumatic valve 58d to open, the second source valve SV to open, and the air pump 80 to create a negative pressure in the second pneumatic pump chamber 70b, thereby pulling the flexible membrane of the second fluid pump chamber 112b into the second pneumatic pump chamber 70b and pulling fresh or used PD fluid into the second fluid pump chamber.

Fig. 24 shows that eventually the first flexible membrane of the first fluid pump chamber 112a cannot collapse further, thereby causing the reading at the first pressure sensor 44a to peak, at which point the control unit 100 stops the pump-out translation of the piston head 36 and closes the first destination fluid valve DV. Alternatively or additionally, detection that the flexible membrane cannot collapse further may again be determined by the control unit 100 detecting that the linear actuator 40 and/or piston head 36 are not moving while maintaining a desired pressure (e.g., 1.5 psig). In any event, after stopping pump-out translation, first pneumatic valve 58a remains open to allow the positive pressure that has been maintained at the desired pressure to equilibrate between cylinder chamber 30a and first pneumatic pump chamber 70a, and this positive pressure may be read by first pressure sensor 44 a. The piston head 36 is now in the final piston head position within the cylinder chamber 30 a. The volume difference of cylinder 30 at the known cross-sectional area between the final piston head position and the initial piston head position is the volume of fresh or used PD fluid calculated by control unit 100 to pump to the desired fluid destination FD due to the same pressure at the initial piston head position and the final piston head position (e.g., 1.5psig, which is the desired pump-to-patient pressure). For fluid extraction from the second fluid pump chamber 112b, the control unit 100 may again monitor the speed of the air pump 80. When the speed of the air pump 80 begins to drop beyond the threshold, the control unit 100 determines that the flexible membrane of the second fluid pump chamber 112b is fully pulled and inflated and, thus, the second fluid pump chamber is filled with fresh or used PD fluid, at which point the control unit stops the air pump 80 and closes the second source fluid valve SV for the second fluid pump chamber 112 b.

The control unit 100 then retracts the piston 32 to the initial position and repeats the above process, but with the first fluid pump chamber 112a filled with fresh or used PD fluid and the second fluid pump chamber 112b pushing the fresh or used PD fluid to the desired fluid destination FD. The control unit 100 accumulates the known stroke volume and continues to perform the alternating pumping sequence just described until a desired or prescribed amount of fresh or used PD fluid is delivered to the desired fluid destination FD.

Fifth main embodiment

Fig. 25-28 illustrate a fifth primary embodiment of the system 10, which, like the fourth primary embodiment, also uses an air pump 80, the air pump 80 operating in cooperation with the air cylinder 30 to drive two pneumatic pump chambers 70a, 70b and their corresponding fluid pump chambers 112a, 112b. In the fourth main embodiment, the cylinder 30 is unidirectional with respect to fluid volume metering because only one side of the piston head 36 (chamber 30 a) within the cylinder is exposed to the first and second pressure sensors 44a, 44b. In the fourth embodiment, after each fluid pump chamber extraction/fluid pump chamber delivery sequence, the piston 32 needs to be reset accordingly. In the fifth primary embodiment, a fifth pneumatic line 56e is added that extends from the first pneumatic line 56a to the opposite side of the cylinder 30 such that there is pneumatic access to the cylinder on both sides of the piston head 36. A fifth pneumatic valve 58e is provided to operate with the fifth pneumatic line 56 e. A sixth pneumatic valve 58f is added along the first pneumatic line 56a as a second valve that allows the cylinder 30 at chamber 30b to be closed.

Fig. 25 shows that in a pumping sequence using the fifth main embodiment of the system 10, the control unit 100 opens the second pneumatic valve 58b and the fifth pneumatic valve 58f, opens the second destination fluid valve DV, and moves the piston head 36 of the cylinder 30 in the first direction to deliver fresh or used PD fluid from the second fluid pump chamber 112b to the desired destination FD. At the same time, the control unit 100 causes the third pneumatic valve 58c and the first source fluid valve SV to open so that the air pump 80 can apply negative pressure to the flexible membrane of the first fluid pump chamber 112a, thereby pulling fresh or used PD fluid into the first fluid pump chamber.

Fig. 26 shows that eventually the second flexible membrane of the second fluid pump chamber 112b cannot collapse further, resulting in a peak reading at the second pressure sensor 44b, at which point the control unit 100 stops the pump-out translation of the piston head 36 and closes the second destination fluid valve DV. Alternatively or additionally, detection that the flexible membrane cannot collapse further may again be determined by the control unit 100 detecting that the linear actuator 40 and/or piston head 36 are not moving while maintaining a desired pressure (e.g., 1.5 psig). In any event, after stopping the pump-out translation, second pneumatic valve 58b and fifth pneumatic valve 58e remain open to allow the positive pressure that has been maintained at the desired pressure to equilibrate between cylinder chamber 30a and second pneumatic pump chamber 70b, and this positive pressure can be read by second pressure sensor 44 b. The volume difference of cylinder 30 at the known cross-sectional area between the initial piston head position and the final piston head position is the volume of fresh or used PD fluid calculated by control unit 100 to pump to the desired fluid destination DV due to the same pressure at the initial piston head position and the final piston head position (e.g., 1.5psig, which is the desired pump-to-patient pressure). For fluid extraction from the first fluid pump chamber 112a, the control unit 100 may again monitor the speed of the air pump 80. When the speed of the air pump 80 begins to drop beyond the threshold, the control unit 100 determines that the flexible membrane of the first fluid pump chamber 112a is fully pulled and inflated and, thus, the first fluid pump chamber is filled with fresh or used PD fluid, at which point the control unit 100 stops the air pump 80 and closes the first source fluid valve SV for the first fluid pump chamber 112 a.

Fig. 27 shows that, next, the first fluid pump chamber 112a and the second fluid pump chamber 112b are switched to operate such that the second fluid pump chamber 112b draws fresh or used PD fluid while the first fluid pump chamber 112a delivers fresh or used PD fluid. Notably, there is no need to adjust the piston head 36 to prepare the cylinder 30 for such switching. Here, the control unit 100 causes the first and sixth pneumatic valves 58a, 58f to open, causes the first destination fluid valve DV to open, and causes the piston head 36 of the cylinder 30 to move in the second direction to deliver fresh or used PD fluid from the first fluid pump chamber 112a to the desired fluid destination FD. At the same time, the control unit 100 causes the fourth pneumatic valve 58d and the second source fluid valve SV to open so that the air pump 80 can apply negative pressure to the flexible membrane of the second fluid pump chamber 112b, thereby drawing fresh or used PD fluid into the second fluid pump chamber.

Fig. 28 shows that eventually the first flexible membrane of the first fluid pump chamber 112a cannot collapse further, resulting in a peak reading at the first pressure sensor 44a, at which point the control unit 100 stops the pump-out translation of the piston head 36 and closes the first destination fluid valve DV. Alternatively or additionally, detection that the flexible membrane cannot collapse further may again be determined by the control unit 100 detecting that the linear actuator 40 and/or piston head 36 are not moving while maintaining a desired pressure (e.g., 1.5 psig). In any event, after stopping the pump-out translation, first pneumatic valve 58a and sixth pneumatic valve 58f remain open to allow the positive pressure that has been maintained at the desired pressure to equilibrate between second cylinder chamber 30b and first pneumatic pump chamber 70a, and this positive pressure can be read by first pressure sensor 44 a. The volume difference of cylinder 30 at the known cross-sectional area between the initial piston head position and the final piston head position is the volume of fresh or used PD fluid calculated by control unit 100 to pump to the desired fluid destination FD due to the same pressure at the initial piston head position and the final piston head position (e.g., 1.5psig, which is the desired pump-to-patient pressure). For fluid extraction from the second fluid pump chamber 112b, the control unit 100 may again monitor the speed of the air pump 80. When the speed of the air pump 80 begins to drop beyond the threshold, the control unit 100 determines that the flexible membrane of the second fluid pump chamber 112b is fully pulled and inflated and thus the second fluid pump chamber is filled with fresh or used PD fluid, at which point the control unit 100 stops the air pump 80 and closes the second source fluid valve SV for the second fluid pump chamber 112 b.

The control unit 100 accumulates the known stroke volume and continues to perform the alternating pumping sequence just described until a desired or prescribed amount of fresh or used PD fluid is delivered to the desired fluid destination FD. It should be appreciated that for any of the first through fifth primary embodiments described above, the delivery pressure may be higher, for example up to 8psig, for fresh or used PD fluid destinations (e.g., heater vessel 116a or drain vessel 116 b) that do not involve the patient. It is also contemplated that for any of the first through fifth primary embodiments, the control unit 100 monitors the associated first pressure sensor 44a or second pressure sensor 44b as the cylinder 30 or air pump 80 removes spent PD fluid from the patient so that the patient discharge negative pressure limit (e.g., -1.5 psig) is not met or exceeded.

It should be appreciated that the drift effects in the pneumatic pressure sensors 44a, 44b used in the above embodiments are offset in that the important aspect of the sequence described above involving the cylinder 30 is that the initial and final pressures associated with fresh or used PD fluid delivery are equal, rather than the pressures being accurate from an absolute point of view (except for the patient pumping pressure limit). Moreover, because the system 10 is pressure controlled, the linear actuator 40 need not be highly accurate.

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

Claims

1. A peritoneal dialysis system comprising:

a pneumatic pump chamber;

A cylinder;

a piston including a piston head slidably sealed within the cylinder, the piston head separating a first cylinder chamber from a second cylinder chamber;

a linear actuator in mechanical communication with the piston;

A first pneumatic line extending between the first cylinder chamber and the pneumatic pump chamber;

a second pneumatic line extending between the second cylinder chamber and the pneumatic pump chamber;

a first pneumatic valve positioned along the first pneumatic line;

a second pneumatic valve positioned along the second pneumatic line;

a pressure sensor positioned and arranged to measure pressure in the pneumatic pump chamber;

a fluid pump chamber operably coupled with the pneumatic pump chamber;

a source fluid valve;

destination fluid valve, and

A control unit configured to (i) cause the second pneumatic valve and the source fluid valve to open and cause the linear actuator to move the piston head into the first cylinder chamber so as to generate a negative pneumatic pressure in the second cylinder chamber and the pneumatic pump chamber, thereby pulling a source fluid into the fluid pump chamber, and (ii) cause the second pneumatic valve and the source fluid valve to close, cause the first pneumatic valve and the destination fluid valve to open and cause the linear actuator to move the piston head further into the first cylinder chamber so as to push a source fluid through the destination fluid valve, and wherein the control unit uses an output from the pressure sensor to control the linear actuator such that a final pressure for (ii) is at least substantially equal to an initial pressure for (ii) such that a volume of a space corresponding to movement of the piston head within the cylinder during (ii) is equal to a volume of fluid delivered from the pump chamber during (ii).

2. The peritoneal dialysis system of claim 1, wherein the source fluid valve is for a PD fluid supply vessel, a heating vessel, or a patient line.

3. The peritoneal dialysis system of claim 1, wherein the destination fluid valve is used to heat a container, drain container, or patient line.

4. The peritoneal dialysis system of claim 1, wherein the volume of space corresponding to movement of the piston head within the cylinder varies with the distance the piston head moves within the cylinder and the cross-sectional area of the inner diameter of the cylinder.

5. The peritoneal dialysis system of claim 1, wherein the control unit is configured to determine the volume of source fluid delivered from the fluid pump chamber during (ii) with both the source fluid valve and the destination fluid valve closed.

6. The peritoneal dialysis system of claim 1, wherein the control unit is further configured to, with the first pneumatic valve and the destination fluid valve closed, (iii) cause the second pneumatic valve and the source fluid valve to open to allow negative pneumatic pressure in the second cylinder chamber generated during at least one of (i) or (ii) to reach the pneumatic pump chamber, thereby drawing source fluid into the fluid pump chamber.

7. The peritoneal dialysis system of claim 6, wherein the control unit is further configured to (iv) cause the linear actuator to move the piston head into the second cylinder chamber with the first pneumatic valve, the source fluid valve, and the destination fluid valve closed and the second pneumatic valve closed so as to generate at least substantially zero pressure in the first and second cylinder chambers.

8. The peritoneal dialysis system of claim 7, wherein the control unit is further configured (v) to cause the second pneumatic valve and the destination fluid valve to open and cause the linear actuator to move the piston head into the second cylinder chamber so as to push a source fluid through the destination fluid valve, and wherein the control unit uses the output from the pressure sensor to control the linear actuator such that a final pressure for (v) is at least substantially equal to an initial pressure for (v) such that a volume of space corresponding to movement of the piston head within the cylinder during (v) is equal to a volume of source fluid delivered from a fluid pump chamber during (v).

9. The peritoneal dialysis system of claim 8, wherein the control unit is further configured to (vi) cause the first pneumatic valve and the source fluid valve to open with the second pneumatic valve and the destination fluid valve closed to allow negative pneumatic pressure in the first cylinder chamber generated during (v) to reach the pneumatic pump chamber, thereby drawing source fluid into the fluid pump chamber.

10. A peritoneal dialysis system comprising:

a pneumatic pump chamber;

A cylinder;

a piston including a piston head slidably sealed within the cylinder;

a linear actuator in mechanical communication with the piston;

An air pump;

A first pneumatic line extending between the cylinder and the pneumatic pump chamber;

a second pneumatic line extending between the air pump and the pneumatic pump chamber;

a first pneumatic valve positioned along the first pneumatic line;

a second pneumatic valve positioned along the second pneumatic line;

a fluid pump chamber operably coupled with the pneumatic pump chamber;

a source fluid valve;

destination fluid valve, and

A control unit configured to (i) cause the second pneumatic valve and the source fluid valve to open and cause the air pump to generate a negative pneumatic pressure in the pneumatic pump chamber to pull a source fluid into the fluid pump chamber, (ii) cause the source fluid valve to close and, with the second pneumatic valve open, cause the air pump to generate a desired positive pressure in the pneumatic pump chamber measured by the pressure sensor, and (iii) cause the second pneumatic valve to close, cause the first pneumatic valve and the destination fluid valve to open and cause the linear actuator to move the piston head within the cylinder so as to push a source fluid through the destination fluid valve, and wherein the control unit uses an output from the pressure sensor to control the linear actuator such that a final pressure for (iii) is at least substantially equal to an initial pressure for (iii) such that a volume of space corresponding to movement of the piston head within the cylinder during (iii) is equal to a volume of fluid delivered from the source of the pump chamber (iii).

11. The peritoneal dialysis system of claim 10, wherein the source fluid valve is for a PD fluid supply vessel, a heating vessel, or a patient line.

12. The peritoneal dialysis system of claim 10, wherein the destination fluid valve is used to heat a container, drain container, or patient line.

13. The peritoneal dialysis system of claim 10, wherein the volume of space corresponding to movement of the piston head within the cylinder varies with the distance the piston head moves within the cylinder and the cross-sectional area of the inner diameter of the cylinder.

14. The peritoneal dialysis system of claim 10, wherein during (i) the first pneumatic valve is open.

15. The peritoneal dialysis system of claim 10, wherein the control unit is further configured to (iv) cause the linear actuator to move the piston head in an opposite direction within the cylinder with the first pneumatic valve and the source fluid valve open, thereby pulling a source fluid into the fluid pump chamber.

16. The peritoneal dialysis system of claim 15, wherein during (iv) the first pneumatic valve is opened and the air pump is actuated to assist in drawing a source of fluid into the fluid pump chamber.

17. A peritoneal dialysis system comprising:

A first pneumatic pump chamber;

a second pneumatic pump chamber;

A cylinder;

a piston including a piston head slidably sealed within the cylinder;

a linear actuator in mechanical communication with the piston;

An air pump;

a first pneumatic line extending between the cylinder and the first pneumatic pump chamber;

A second pneumatic line extending between the cylinder and the second pneumatic pump chamber;

a third pneumatic line extending between the air pump and the first pneumatic pump chamber;

a fourth pneumatic line extending between the air pump and the second pneumatic pump chamber;

a first pneumatic valve positioned along the first pneumatic line;

a second pneumatic valve positioned along the second pneumatic line;

a third pneumatic valve positioned along a third pneumatic line;

a fourth pneumatic valve is provided, which is provided with a first valve, the fourth pneumatic valve is positioned along the fourth pneumatic line;

a first pressure sensor positioned and arranged to measure pressure in the first pneumatic pump chamber;

a second pressure sensor positioned and arranged to measure pressure in the second pneumatic pump chamber;

A first fluid pump chamber operatively coupled with the first pneumatic pump chamber;

A first source fluid valve for the first pump chamber;

a first destination fluid valve is provided which, the first destination fluid valve is for the first pump chamber;

a second fluid pump chamber operatively coupled with the first pneumatic pump chamber;

a second source fluid valve for the second pump chamber;

A second destination fluid valve for the second pump chamber, and

A control unit configured to generate negative and positive pneumatic pressures in the first and second pneumatic pump chambers using the air pump and actuate the linear actuator to move the piston head within the cylinder while equalizing the initial and final positive pneumatic pressures to meter determinable volumes of source fluid through the first and second destination fluid valves.

18. The peritoneal dialysis system of claim 17, wherein the control unit is configured to:

(i) With the third pneumatic valve and the first source fluid valve open, causing the air pump to generate a negative pneumatic pressure in the first pneumatic pump chamber, thereby drawing a source fluid into the first fluid pump chamber,

(Ii) Causing the air pump to generate a desired positive air pressure in the first air pump chamber, measured by the first pressure sensor, with the third air valve open and the first source fluid valve closed, and

(Iii) Causing the linear actuator to move the piston head within the cylinder with the first pneumatic valve and the first destination fluid valve open so as to push a source fluid through the first destination fluid valve, and wherein the control unit uses output from the first pressure sensor to control the linear actuator such that a final pressure for (iii) is at least substantially equal to an initial pressure for (iii) such that a volume of space corresponding to movement of the piston head within the cylinder during (iii) is equal to a volume of a source fluid delivered from the first fluid pump chamber during (iii), and causing the air pump to generate a negative pneumatic pressure in the second pneumatic pump chamber with the fourth pneumatic valve and the second source fluid valve open so as to pull a source fluid into the second fluid pump chamber.

19. The peritoneal dialysis system of claim 18, wherein the control unit is further configured to, with the piston head moved to the retracted position:

(iv) Causing the air pump to generate a desired positive air pressure in the second air pump chamber, measured by the first pressure sensor, with the fourth air valve open and the second source fluid valve closed, and

(V) Causing the linear actuator to move the piston head within the cylinder with the second pneumatic valve and the second destination fluid valve open so as to push a source fluid through the second destination fluid valve, and wherein the control unit uses output from the second pressure sensor to control the linear actuator such that a final pressure for (v) is at least substantially equal to an initial pressure for (v) such that a volume of space corresponding to movement of the piston head within the cylinder during (v) is equal to a volume of a source fluid delivered from the second fluid pump chamber during (v), and causing the air pump to generate a negative pneumatic pressure in the first pneumatic pump chamber with the third pneumatic valve and the first source fluid valve open so as to pull source fluid into the first fluid pump chamber.

20. A peritoneal dialysis system comprising:

A first pneumatic pump chamber;

a second pneumatic pump chamber;

A cylinder;

a linear actuator in mechanical communication with the piston;

An air pump;

a first pneumatic line extending between the second cylinder chamber and the first pneumatic pump chamber;

a second pneumatic line extending between the second cylinder chamber and the second pneumatic pump chamber;

a fifth pneumatic line extending between the first cylinder chamber and the first pneumatic line;

a first pneumatic valve positioned along the first pneumatic line;

a second pneumatic valve positioned along the second pneumatic line;

a third pneumatic valve positioned along a third pneumatic line;

A fifth pneumatic valve positioned along the fifth pneumatic line;

A sixth pneumatic valve positioned adjacent the second cylinder chamber;

A first source fluid valve for the first pump chamber;

a second source fluid valve for the second pump chamber;

A second destination fluid valve for the second pump chamber, and

A control unit configured to generate negative and positive pneumatic pressures in the first and second pneumatic pump chambers using the air pump and actuate the linear actuator to move the piston head within the first and second cylinder chambers while equalizing the initial and final positive pneumatic pressures to meter determinable volumes of source fluid through the first and second destination fluid valves.

21. The peritoneal dialysis system of claim 20, wherein the control unit is configured to:

(i) With the third pneumatic valve and the first source fluid valve open, causing the air pump to generate a negative pneumatic pressure in the first pneumatic pump chamber, thereby drawing a source fluid into the first fluid pump chamber, and with the second pneumatic valve and the fifth pneumatic valve and the second destination fluid valve open, causing the linear actuator to move the piston head toward the first cylinder chamber so as to push source fluid through the second destination fluid valve, and wherein the control unit uses output from the second pressure sensor to control the linear actuator such that a final pressure for (i) is at least substantially equal to an initial pressure for (i) such that a volume of space corresponding to movement of the piston head toward the first cylinder chamber during (i) is equal to a volume of source fluid delivered from the second fluid pump chamber during (i).

22. The peritoneal dialysis system of claim 21, wherein the control unit is further configured to:

(ii) With the fourth pneumatic valve and the second source fluid valve open, causing the air pump to generate a negative pneumatic pressure in the second pneumatic pump chamber, thereby drawing a source fluid into the second fluid pump chamber, and with the first pneumatic valve and sixth pneumatic valve and the first destination fluid valve open, causing the linear actuator to move the piston head toward the second cylinder chamber so as to push source fluid through the first destination fluid valve, and wherein the control unit uses output from the first pressure sensor to control the linear actuator such that a final pressure for (ii) is at least substantially equal to an initial pressure for (ii) such that a volume of space corresponding to movement of the piston head toward the second cylinder chamber during (ii) is equal to a volume of source fluid delivered from the second fluid pump chamber during (ii).