MEDICAL FLUID PUMPING SYSTEMS AND RELATED DEVICES AND METHODS

• US 20120271226A1
• Filed: 04/09/2012
• Published: 10/25/2012
• Est. Priority Date: 04/21/2011
• Status: Active Grant

• Current Assignee: Fresenius Medical Care Holdings Incorporated (Fresenius Medical Care AG)
• Original Assignee: Fresenius Medical Care Holdings Incorporated (Fresenius Medical Care AG)
• Inventors: Farrell, Sean, Ly, Tri, Plahey, Kulwinder S., Lindley, DeLoy, Singh, Gurpreet, Serrato, Ignacio, Ghatikar, Venugopal Raghavendra, Young, Michael David
• Granted Patent: US 9,180,240 B2
• Time in Patent Office: Days
• US Class Current: 604/29
• CPC Class Codes: A61M 1/14 Dialysis systems; Artificial kidneys; Blood oxygenators semi-permeable membranes characterised by the material, manufacturing processes therefor B01D71/00; Reciprocating systems for treatment of body fluids, e.g. single needle systems for hemofiltration or pheresis
• 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 1/155 with treatment-fluid pumping means or components thereof
• 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 1/159 specially adapted for peritoneal dialysis
• CPC Class Codes: A61M 1/28 Peritoneal dialysis ; Other peritoneal treatment, e.g. oxygenation
• CPC Class Codes: A61M 2205/121 interface between cassette and base
• CPC Class Codes: A61M 5/14212 Pumping with an aspiration and an expulsion action
• CPC Class Codes: A61M 5/14216 Reciprocating piston type
• CPC Class Codes: A61M 5/1452 pressurised by means of pistons
• CPC Class Codes: A61M 60/113 in other functional devices, e.g. dialysers or heart-lung machines
• CPC Class Codes: A61M 60/258 Piston pumps
• CPC Class Codes: A61M 60/37 Haemodialysis, haemofiltration or diafiltration
• CPC Class Codes: A61M 60/441 generated by an electromotor
• CPC Class Codes: A61M 60/835 of positive displacement blood pumps
• CPC Class Codes: F04B 43/02 having plate-like flexible members, e.g. diaphragms F04B43/14 takes precedence

Abstract

This disclosure relates to medical fluid pumping systems and related devices and methods. In some aspects, a medical fluid pumping system includes a medical fluid pumping machine including a piston head that can be linearly displaced and a medical fluid cassette that can be secured to the medical fluid pumping machine. The medical fluid cassette includes a fastening member attached to a region of a flexible membrane overlying a fluid pump chamber, and the piston head is configured to be mechanically connected to the fastening member of the cassette.

Claims

1. A medical fluid pumping system comprising:

a medical fluid pumping machine comprising a piston head that can be linearly displaced;

a medical fluid cassette that can be secured to the medical fluid pumping machine, the medical fluid cassette comprising

a base,

a flexible membrane attached to the base in a manner such that the flexible membrane and the base cooperate to at least partially define a fluid pump chamber, and

a fastening member attached to the flexible membrane, the fastening member defining a recess configured to receive the piston head of the medical fluid pumping machine, and the fastening member having an engagement surface that engages an engagement surface of the piston head when the piston head is disposed in the recess such that, when the piston head is disposed in the recess and is moved linearly away from the base of the cassette, the engagement surface of the piston head is engaged with the engagement surface of the fastening member and pulls the fastening member and the flexible membrane to which the fastening member is attached away from the base to increase a volume of the fluid pump chamber.

2. The medical fluid pumping system of claim 1, wherein the medical fluid cassette can be secured to the medical fluid pumping machine by disposing the medical fluid cassette within a cassette compartment defined by the medical fluid pumping machine.

3. The medical fluid pumping system of claim 1, wherein the fastening member comprises a substantially dome-shaped member.

4. The medical fluid pumping system of claim 3, wherein the engagement surface of the fastening member is a surface of a radially inwardly extending projection of the substantially dome-shaped member.

5. The medical fluid pumping system of claim 3, wherein the fastening member comprises a peg extending from a surface of the dome-shaped member.

6. The medical fluid pumping system of claim 5, wherein the engagement surface of the fastening member is a surface of an enlarged head of the peg.

7. The medical fluid pumping system of claim 1, wherein the piston head comprises a body portion and a contact surface that extends radially beyond a perimeter of the body portion, the contact surface of the piston head being configured to contact a contact surface of the fastening member of the medical fluid cassette when the piston head is inserted into the recess of the fastening member.

8. The medical fluid pumping system of claim 7, wherein the contact surface of the piston head is configured to move radially inwardly when the piston head is inserted into the recess of the fastening member.

9. The medical fluid pumping system of claim 8, wherein the contact surface of the piston head is a surface of a latch that is radially moveable relative to a body portion of the piston head.

10. The medical fluid pumping system of claim 7, wherein the contact surface of the fastening member is configured to deflect radially outwardly when the piston head is inserted into the recess of the fastening member.

11. The medical fluid pumping system of claim 10, wherein the contact surface of the fastening member is a surface of a radially inwardly extending projection of the fastening member.

12. The medical fluid pumping system of claim 1, wherein the piston head comprises a latch secured to a body portion of the piston head, the engagement surface of the piston head is a surface of the latch, and the latch has an extended position in which the surface of the latch is positioned radially outward of a perimeter of the body portion.

13. The medical fluid pumping system of claim 12, wherein the latch has a retracted position in which the surface of the latch is positioned radially inward of the perimeter of the body portion.

14. The medical fluid pumping system of claim 13, wherein the body portion comprises front and rear members, and the latch is positioned in a space defined between the front and rear members.

15. The medical fluid pumping system of claim 14, wherein the piston head further comprises a latch lock having a first angled surface that sits adjacent an associated first angled surface of the latch such that radially inward movement of the latch causes axial movement of the latch lock in a first axial direction.

16. The medical fluid pumping system of claim 15, wherein the piston head further comprises a spring disposed between the latch lock and the front member to resist the axial movement of the latch lock in the first axial direction.

17. The medical fluid pumping system of claim 16, wherein the latch and the latch lock are configured such that when a force applied to the latch to move the latch radially inwardly and to move the latch lock axially is released, the spring expands and moves the latch lock in a second axial direction opposite the first axial direction and causes the latch to move radially outwardly.

18. The medical fluid pumping system of claim 1, wherein the piston head comprises a body portion and a flange that extends at least partially around a perimeter of the body portion, and the engagement surface of the piston head is a surface of the flange of the piston head.

19. The medical fluid pumping system of claim 18, wherein the fastening member has a projection that extends at least partially around a perimeter of the recess, and the engagement surface of the fastening member is a surface of the projection of the fastening member.

20. The medical fluid pumping system of claim 1, wherein the piston head comprises a clamp, the fastening member comprises a peg configured to be releasably engaged by the clamp, and the engagement surfaces of the piston head and the fastening member are surfaces of the clamp and the peg, respectively.

21. The medical fluid pumping system of claim 1, wherein the piston head and the fastening member are constructed to become mechanically connected when the piston head is moved toward the base of the cassette and to become disconnected when the piston head is moved away from the base of the cassette.

22. The medical fluid pumping system of claim 21, wherein the piston head is disposed within the recess of the fastening member and the engagement surfaces contact one another when the piston head and the fastening member are mechanically connected.

23. The medical fluid pumping system of claim 1, wherein the medical fluid pumping machine is a dialysis machine.

24. A medical fluid cassette comprising:

a base,

a flexible membrane attached to the base in a manner such that the flexible membrane and the base cooperate to at least partially define a fluid pump chamber, and

a fastening member attached to the flexible membrane, the fastening member defining a recess configured to receive a piston head of a medical fluid pumping machine and having an engagement surface that engages the piston head when the piston head is disposed in the recess such that, when the piston head is disposed in the recess and is moved linearly away from the base of the cassette, the piston head engages the engagement surface of the fastening member to pull the fastening member and the flexible membrane to which the fastening member is attached away from the base and increase a volume of the fluid pump chamber.

25. The medical fluid cassette of claim 24, wherein the medical fluid cassette can be secured to the medical fluid pumping machine by disposing the medical fluid cassette within a cassette compartment defined by the medical fluid pumping machine.

26. The medical fluid cassette of claim 24, wherein the fastening member comprises a substantially dome-shaped member.

27. The medical fluid cassette of claim 26, wherein the engagement surface of the fastening member is a surface of a radially inwardly extending projection of the substantially dome-shaped member.

28. The medical fluid cassette of claim 26, wherein the fastening member comprises a peg extending from a surface of the dome-shaped member.

29. The medical fluid cassette of claim 28, wherein the engagement surface of the fastening member is a surface of an enlarged head of the peg.

30. The medical fluid cassette of claim 24, wherein the fastening member is constructed to become mechanically connected to the piston head when the piston head is moved toward the base of the cassette and to become disconnected from the piston head when the piston head is moved away from the base of the cassette.

31. The medical fluid cassette of claim 24, wherein the medical fluid cassette is a dialysis fluid cassette.

32. A medical fluid pumping machine comprising:

a piston head that can be linearly displaced, the piston head being configured to be disposed within a recess defined by a fastening member of a medical fluid cassette, and the piston head having an engagement surface configured to engage an engagement surface of the medical fluid cassette when the piston head is disposed in the recess such that, when the piston head is disposed in the recess and is moved linearly away from a base of the cassette, the engagement surface of the piston head is engaged with the engagement surface of the fastening member and pulls the fastening member and a flexible membrane to which the fastening member is attached away from the base to increase a volume of a fluid pump chamber defined in the cassette between the flexible membrane and the base.

33. The medical fluid pumping machine of claim 32, wherein the piston head comprises a body portion and a contact surface that extends radially beyond a perimeter of the body portion.

34. The medical fluid pumping machine of claim 33, wherein the contact surface of the piston head is configured to move radially inwardly when the piston head is inserted into the recess of the fastening member.

35. The medical fluid pumping machine of claim 34, wherein the contact surface of the piston head is a surface of a latch that is radially moveable relative to a body portion of the piston head.

36. The medical fluid pumping machine of claim 32, wherein the piston head comprises a latch secured to a body portion of the piston head, the engagement surface of the piston head is a surface of the latch, and the latch has an extended position in which the surface of the latch is positioned radially outward of a perimeter of the body portion.

37. The medical fluid pumping machine of claim 36, wherein the latch has a retracted position in which the surface of the latch is positioned radially inward of the perimeter of the body portion.

38. The medical fluid pumping machine of claim 32, wherein the piston head comprises a body portion and a flange that extends at least partially around a perimeter of the body portion, and the engagement surface of the piston head is a surface of the flange of the piston head.

39. The medical fluid pumping machine of claim 32, wherein the piston head comprises a clamp configured to engage a portion of the fastening member of the medical fluid cassette when the piston head is disposed in the recess of the fastening member of the medical fluid cassette.

40. The medical fluid pumping machine of claim 32, wherein the piston head is constructed to become mechanically connected to the fastening member when the piston head is moved toward the base of the cassette and to become disconnected from the fastening member when the piston head is moved away from the base of the cassette.

41. The medical fluid pumping machine of claim 32, wherein the medical fluid pumping machine is a dialysis machine.

42. A medical fluid pumping method comprising:

advancing a piston head into a recessed region of a fastening member of a medical fluid cassette to mechanically connect the piston head to the fastening member; and

then

reciprocating the piston head to cause the fastening member to alternately retract and advance, which causes fluid to alternately be drawn into a fluid pump chamber of the cassette and forced out of the fluid pump chamber of the cassette.

43. The medical fluid pumping method of claim 42, wherein the piston head is advanced into the recessed region of the fastening member with an axial force of about 5 lbf to about 50 lbf.

44. The medical fluid pumping method of claim 42, further comprising, after reciprocating the piston head, retracting the piston head a certain distance to disconnect the piston head from the fastening member of the medical fluid cassette.

45. The medical fluid pumping method of claim 42, wherein the piston head is retracted out of the recessed region of the fastening member with an axial force of at least 50 pounds.

46. The medical fluid pumping method of claim 42, wherein the medical fluid cassette comprises a base, a flexible membrane attached to the base in a manner such that the flexible membrane and the base cooperate to at least partially define the fluid pump chamber, and the fastening member attached to the flexible membrane, the fastening member having an engagement surface that engages an engagement surface of the piston head when the piston head is disposed in the recess such that, when the piston head is disposed in the recess and is moved linearly away from the base of the cassette, the engagement surface of the piston head is engaged with the engagement surface of the fastening member and pulls the fastening member and the flexible membrane to which the fastening member is attached away from the base to increase a volume of the fluid pump chamber and draw fluid into the fluid pump chamber.