Automated dialysis pumping system using stepper motor

• US 7,789,849 B2
• Filed: 12/21/2006
• Issued: 09/07/2010
• Est. Priority Date: 05/24/2002
• Status: Expired due to Term

• Current Assignee: Baxter Healthcare SA (Baxter International Inc.), Baxter International Inc.
• Original Assignee: Baxter Healthcare SA (Baxter International Inc.), Baxter International Inc.
• Inventors: Lundtveil, Loren M., Eu, Bruce Ming-Da, Alvaro, Jose, Din, Shahid, Bowman, Joseph H. Jr., Busby, Don, Lauman, Brian, Shang, Sherwin, Kienman, Rick, Richardson, Ian, Hopping, Peter, Childers, Robert
• Primary Examiner(s): Lucchesi; Nicholas D
• Assistant Examiner(s): STOHR, LEAH C
• Application Number:
  US11/614,850
• Publication Number:
  US 20070213651A1
• Time in Patent Office: 1,356 Days
• Field of Search: 604/29, 604 65- 67, 604/72, 604/113
• US Class Current: 604/29
• CPC Class Codes: A61M 1/1522 the interface being evacuated interfaces to enhance contact
• CPC Class Codes: A61M 1/1524 the interface providing means for actuating on functional elements of the cassette, e.g. plungers
• CPC Class Codes: A61M 1/153 the cassette being adapted for heating or cooling the treating fluid, e.g. the dialysate or the treating gas
• CPC Class Codes: A61M 1/155 with treatment-fluid pumping means or components thereof
• CPC Class Codes: A61M 1/156 Constructional details of the cassette, e.g. specific details on material or shape
• CPC Class Codes: A61M 1/1561 at least one cassette surface or portion thereof being flexible, e.g. the cassette having a rigid base portion with preformed channels and being covered with a foil
• CPC Class Codes: A61M 1/1565 Details of valves
• CPC Class Codes: A61M 1/159 specially adapted for peritoneal dialysis
• CPC Class Codes: A61M 1/166 Heating for sterilisation A61M1/1686
• CPC Class Codes: A61M 1/267 used for pumping
• CPC Class Codes: A61M 1/28 Peritoneal dialysis ; Other peritoneal treatment, e.g. oxygenation
• CPC Class Codes: A61M 1/281 Instillation other than by gravity
• CPC Class Codes: A61M 1/288 Priming priming in extracorporeal blood circuits A61M1/3643
• CPC Class Codes: A61M 2205/127 with provisions for heating or cooling
• CPC Class Codes: A61M 2205/50 with microprocessors or computers
• CPC Class Codes: A61M 2205/581 by audible feedback
• CPC Class Codes: A61M 2205/583 by visual feedback

Abstract

A peritoneal dialysis system includes: (i) an enclosure; (ii) a stepper motor housed by the enclosure; (iii) a pump head in operable communication with the stepper motor; and (iv) a disposable unit including at least one flexible membrane attached to a rigid piece, the enclosure configured to receive the disposable unit such that the stepper motor can move the pump head towards and away from the flexible membrane to cause, (a) the flexible membrane to move outwardly with respect to the rigid piece as the pump head is moved away from the disposable unit, and (b) the flexible membrane to move inwardly with respect to the rigid piece as the pump head is moved away from the disposable unit.

Claims

1. A peritoneal dialysis system comprising:

an enclosure;

a stepper motor housed by the enclosure;

a pump head in operable communication with the stepper motor;

a disposable unit including at least one flexible membrane attached to a rigid piece, the enclosure and the disposable unit configured to allow a negative pressure to exist between the pump head and the flexible membrane and to pull the flexible membrane to a position that extends beyond a relaxed position of the membrane, the enclosure configured to receive the disposable unit such that the stepper motor can move the pump head towards and away from the flexible membrane to cause,

the flexible membrane to move outwardly with respect to the rigid piece as the pump head is moved away from the disposable unit, and

the flexible membrane to move inwardly with respect to the rigid piece as the pump head is moved towards the disposable unit; and

an encoder operable with the stepper motor to indicate a position of the pump head after the pump head has moved towards or away from the flexible membrane, the encoder configured to indicate the pump head position after a power loss.

2. The peritoneal dialysis system of claim 1, which includes a ball screw in operable communication with the stepper motor and the pump head, the ball screw operable to convert a rotational output of the stepper motor to a translational motion of the pump head.

3. The peritoneal dialysis system of claim 2, which includes a pump piston coupled to the pump head and operable with the ball screw.

4. The peritoneal dialysis system of claim 1, wherein the stepper motor is a linear stepper motor.

5. The peritoneal dialysis system of claim 1, wherein the encoder is an absolute encoder that provides an absolute pump head position after a power loss.

6. The peritoneal dialysis system of claim 5, which includes a home position, the absolute encoder indicating how far from the home position the pump head has traveled.

8. The peritoneal dialysis system of claim 6, wherein the home position is a zero degree position for the encoder.

22. The peritoneal dialysis system of claim 1, further comprising a portable hardware unit.

23. The peritoneal dialysis system of claim 1, the enclosure defining an interior and including a pump shell, a valve actuator and a heater.

24. The peritoneal dialysis system of claim 23, the disposable unit removably and operably positionable with respect to the interior of the enclosure, the disposable unit having a pump portion that forms a pump chamber with the shell of the enclosure, a valve portion that is moved by the valve actuator and a heating portion that is heated by the heater.

25. The peritoneal dialysis system of claim 24, further comprising a pump actuator configured to pneumatically and mechanically move the pump portion of the disposable unit with respect to the pump shell of the enclosure.

26. The peritoneal dialysis system of claim 1, which includes a processor that coordinates operation of a pump actuator, a valve actuator and a heater.

27. The peritoneal dialysis system of claim 26, wherein the processor communicates with a plurality of sensors, wherein the sensors are selected from the group consisting of:

a capacitance fluid volume sensor, a dialysis fluid temperature sensor, a pressure sensor, a vacuum sensor, an air detection sensor and a mechanical positioning sensor.

28. The dialysis system of claim 22, wherein the hardware unit includes a display device that provides dialysis system information.

29. The dialysis system of claim 23, wherein the valve actuator includes a camshaft and a plurality of cams.

30. The dialysis system of claim 23, wherein the heater includes at least one of:

a heating plate, an infrared heating source and a configuration suitable for in-line heating.

31. The dialysis system of claim 1, wherein the disposable unit includes an at least substantially rigid member bonded to a first flexible membrane and a second flexible membrane, the member and membranes defining at least part of a valve portion of the disposable unit, the valve portion being (i) mechanically actuated by a valve actuator including a valve motor and a camshaft or (ii) pneumatically actuated by a vacuum source.

32. The dialysis system of claim 1, the disposable unit further comprising a pump portion, the pump portion formed from a first flexible membrane and a second membrane, and a valve portion including an at least semi-rigid member connected to the first and second membranes, the pump portion being (i) mechanically actuated by a mechanical actuator including a pump motor and a liner pump actuator or (ii) pneumatically actuated by a vacuum source.

33. The dialysis system of claim 1, the disposable unit further comprising a heating portion which includes a fluid heating pathway in fluid communication with a pump portion and a valve portion.

34. The dialysis system of claim 22, wherein the hardware unit is configured to be manually transported to a patient'"'"'s home and opened so that the patient can place the disposable unit therein and closed so that the dialysis system and the disposable unit cooperatively form a pump chamber that enables dialysis fluid to be pumped to and from the patient.

35. The dialysis system of claim 1, wherein the disposable unit is configured so that at least one of:

(i) the disposable unit in operation resides between a first portion and a second portion of a heater; and

(ii) in operation dialysis fluid within the disposable unit expands at least a portion of the unit to contact the first and second portions of the heater.

7. A peritoneal dialysis system comprising:

an enclosure;

a stepper motor housed by the enclosure;

a pump head in operable communication with the stepper motor;

a disposable unit including at least one flexible membrane attached to a rigid piece, the enclosure and the disposable unit configured to allow a negative pressure to exist between the pump head and the flexible membrane and to pull the flexible membrane to a position that extends beyond a relaxed position of the membrane, the enclosure configured to receive the disposable unit such that the stepper motor can move the pump head towards and away from the flexible membrane to cause,

the flexible membrane to move outwardly with respect to the rigid piece as the pump head is moved away from the disposable unit, and

the flexible membrane to move inwardly with respect to the rigid piece as the pump head is moved towards the disposable unit; and

an encoder operable with the stepper motor to indicate a position of the pump head after the pump head has moved towards or away from the flexible member membrane, the absolute encoder configured to indicate how far from a home position the pump head has traveled.

42. The peritoneal dialysis system of claim 7, wherein the home position is a fully opened or fully closed position for the membrane with respect to the rigid piece of the disposable unit.

9. A peritoneal dialysis system comprising:

an enclosure;

a stepper motor housed by the enclosure and powered by an external source or a battery back-up if external source power is lost;

a rotational to translational conversion mechanism in operable communication with the stepper motor;

a pump head in operable communication with the rotational to translational conversion mechanism;

the enclosure configured to receive a disposable unit, the disposable unit having a moveable membrane operable with the pump head, the enclosure and the disposable unit configured to allow a negative pressure to exist between the pump head and the moveable membrane, the stepper motor and the rotational to translational conversion mechanism in operable communication to move the pump head towards and away from the disposable unit, and wherein the moveable membrane of the disposable unit is positioned to follow the pump head as the head is moved towards the disposable unit;

a controller; and

an encoder operable with the controller to track a position of the pump head, the controller programmed to maintain a location of a home position of the pump head when the stepper motor is powered by the battery back-up.

10. The peritoneal dialysis system of claim 9, wherein the moveable membrane of the disposable unit is in contact with the pump head as the head is moved towards the disposable unit.

11. The peritoneal dialysis system of claim 9, the negative pressure causing the moveable membrane to follow the pump head as the head is moved away from the disposable unit.

12. The peritoneal dialysis system of claim 11, wherein the negative pressure is supplied by an air pump motor that is separate from the pump head.

13. The peritoneal dialysis system of claim 9, wherein the rotational to translational conversion mechanism includes a ball screw.

14. A peritoneal dialysis system comprising:

an enclosure;

a door hingedly attached to the enclosure;

a stepper motor housed by the enclosure;

a pump head in operable communication with the stepper motor;

a disposable unit operable with the enclosure and the door, the disposable unit including a moveable membrane operable with the pump head, the enclosure and the disposable unit configured to allow a negative pressure to exist between the pump head and the moveable membrane, the stepper motor configured to move the pump head towards and away from the disposable unit; and

a rotary encoder operably coupled to the stepper motor, the rotary encoder operable with a position detection apparatus located to detect a position of the pump head relative to a reference position.

15. The peritoneal dialysis system of claim 14, which is configured such that the moveable membrane of the disposable unit moves with the pump head as the pump head is moved towards or away from the disposable unit.

16. The peritoneal dialysis system of claim 14, which is operable with the position detection apparatus such that the position of the pumping head is known upon power-up of the system.

17. The peritoneal dialysis system of claim 14, wherein the position detection apparatus is of a type selected from the group consisting of a linear encoder, a proximity sensor, a magnetic pick-up, and combinations thereof.

18. The peritoneal dialysis system of claim 14, wherein the position detection apparatus is operable with a battery back-up.

19. The peritoneal dialysis system of claim 14, wherein the reference position is a fully opened or fully closed position for the moveable membrane of the disposable unit.

20. The peritoneal dialysis system of claim 14, which is configured to move the pump head automatically upon power-up until the reference position is sensed.

21. The peritoneal dialysis system of claim 14, wherein the pump head is moved to the reference position upon power-up.

36. A peritoneal dialysis system comprising:

an enclosure;

a stepper motor housed by the enclosure;

a pump head in operable communication with the stepper motor;

a disposable unit including at least one flexible membrane attached to a rigid piece, the enclosure and the disposable unit configured to allow a negative pressure to exist between the pump head and the flexible membrane and to pull the flexible membrane to a position that extends beyond a relaxed position of the membrane, the enclosure configured to receive the disposable unit such that the stepper motor can move the pump head towards and away from the flexible membrane to cause,

the flexible membrane to move outwardly with respect to the rigid piece as the pump head is moved away from the disposable unit, and

the flexible membrane to move inwardly with respect to the rigid piece as the pump head is moved towards the disposable unit; and

an encoder operable with the stepper motor to indicate a position of the pump head after the pump head has moved towards or away from the flexible membrane,

wherein the encoder is configured to indicate how far from a home position the pump head has traveled, and

wherein the dialysis system is configured to move the stepper motor automatically upon power-up until the home position is sensed.

37. A peritoneal dialysis system comprising:

an enclosure;

a stepper motor housed by the enclosure and powered by an external source or a battery back-up;

a rotational to translational conversion mechanism in operable communication with the stepper motor;

a pump head in operable communication with the rotational to translational conversion mechanism;

the enclosure configured to receive a disposable unit, the disposable unit having a moveable membrane operable with the pump head, the enclosure and the disposable unit configured to allow a negative pressure to exist between the pump head and the moveable membrane, the stepper motor and the rotational to translational conversion mechanism in operable communication to move the pump head towards and away from the disposable unit, and wherein the moveable membrane of the disposable unit is positioned to follow the pump head as the head is moved towards the disposable unit; and

an encoder configured to indicate a location of a home position of the pump head when the stepper motor is powered by the battery back-up,

the negative pressure causing the moveable membrane to follow the pump head as the head is moved away from the disposable unit, and wherein the negative pressure is supplied by a pneumatic source separate from the pump head.

38. A peritoneal dialysis system comprising:

an enclosure;

a door hingedly attached to the enclosure;

a stepper motor housed by the enclosure;

a pump head in operable communication with the stepper motor;

a disposable unit operable with the enclosure and the door, the disposable unit including a moveable membrane operable with the pump head, the enclosure and the disposable unit configured to allow a negative pressure to exist between the pump head and the moveable membrane, the stepper motor configured to move the pump head towards and away from the disposable unit; and

a position detection apparatus located to detect a position of the pump head relative to a reference position, the pump head located at the reference position upon power-up,

the dialysis system configured to move the pump head automatically upon power-up until the reference position is sensed.

39. A peritoneal dialysis system comprising:

an enclosure defining an interior and including a pump shell, a valve actuator and a heater;

a stepper motor housed by the enclosure;

a pump head in operable communication with the stepper motor;

a disposable unit removably and operably positionable with respect to the interior of the enclosure and including at least one flexible membrane attached to a rigid piece to form (i) a pump portion that forms a pump chamber with the shell of the enclosure and (ii) a valve portion that is moved by the valve actuator, the disposable unit further including a heating portion that is heated by the heater, the enclosure and the disposable unit configured to allow a negative pressure to exist in the pump chamber between the pump head and the flexible membrane and to pull the flexible membrane to a position that extends beyond a relaxed position of the membrane, the enclosure configured to receive the disposable unit such that the stepper motor can move the pump head towards and away from the flexible membrane to cause,

the flexible membrane to move outwardly within the pump chamber and with respect to the rigid piece as the pump head is moved away from the disposable unit, and

the flexible membrane to move inwardly within the pump chamber and with respect to the rigid piece as the pump head is moved towards the disposable unit; and

an encoder operable with the stepper motor to indicate a position of the pump head after the pump head has moved towards or away from the flexible membrane.

40. A peritoneal dialysis system comprising:

an enclosure;

a stepper motor housed by the enclosure;

a pump head in operable communication with the stepper motor;

a disposable unit including flexible membrane bonded to a rigid piece, the rigid piece and the at least one membrane defining at least part of a valve portion of the disposable unit, the enclosure and the disposable unit configured to allow a negative pressure to exist between the pump head and the flexible membrane and to pull the flexible membrane to a position that extends beyond a relaxed position of the membrane, the enclosure configured to receive the disposable unit such that the stepper motor can move the pump head towards and away from the flexible membrane to cause,

the flexible membrane to move outwardly with respect to the rigid piece as the pump head is moved away from the disposable unit, and

the flexible membrane to move inwardly with respect to the rigid piece as the pump head is moved towards the disposable unit; and

an encoder operable with the stepper motor to indicate a position of the pump head after the pump head has moved towards or away from the flexible membrane.

41. A peritoneal dialysis system comprising:

an enclosure;

a stepper motor housed by the enclosure;

a pump head in operable communication with the stepper motor;

a disposable unit including at least one flexible membrane attached to a rigid piece to form a pump portion and a valve portion, the enclosure and the disposable unit configured to allow a negative pressure to exist between the pump head and the flexible membrane and to pull the flexible membrane at the pump portion to a position that extends beyond a relaxed position of the membrane, the enclosure configured to receive the disposable unit such that the stepper motor can move the pump head towards and away from the flexible membrane to cause,

the flexible membrane at the pump portion to move outwardly with respect to the rigid piece as the pump head is moved away from the disposable unit, and

the flexible membrane at the pump portion to move inwardly with respect to the rigid piece as the pump head is moved towards the disposable unit; and

an encoder operable with the stepper motor to indicate a position of the pump head after the pump head has moved towards or away from the flexible membrane.