DIALYSIS FLUID HEATING SYSTEMS

• US 20080021377A1
• Filed: 07/05/2007
• Published: 01/24/2008
• Est. Priority Date: 11/05/2003
• Status: Active Grant

• Current Assignee: Baxter Healthcare SA (Baxter International Inc.), Baxter International Inc.
• Original Assignee: Baxter Healthcare SA (Baxter International Inc.), Baxter International Inc.
• Inventors: Slepicka, James, Ding, Yuanpang, Twining, Amy, Ozer, Mehmet, Bobart, George, Hecht, Gideon, Yardimci, Atif, Reitz, Douglas, Lauman, Brian, Busby, Donald, Kopychev, Andrey, Chan, William, Kienman, Richard, Roush, Dan, Lindsay, Jennifer, Steck, John
• Granted Patent: US 8,803,044 B2
• Time in Patent Office: Days
• US Class Current: 604/29
• 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 1/1561 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 1/1635 with volume chamber balancing devices between used and fresh dialysis fluid
• CPC Class Codes: A61M 1/1696 with dialysate regeneration
• CPC Class Codes: A61M 1/342 Adding solutions to the blood, e.g. substitution solutions for preventing coagulation A61M1/3672
• CPC Class Codes: A61M 1/3434 with pre-dilution and post-dilution
• CPC Class Codes: A61M 1/3437 downstream of the filter, e.g. post-dilution with filtrate
• CPC Class Codes: A61M 1/3458 having electrolytes not present in the dialysate
• CPC Class Codes: A61M 2205/127 with provisions for heating or cooling
• CPC Class Codes: A61M 5/44 having means for cooling or heating the devices or media

Abstract

A dialysis fluid heating system includes a plurality of conductive tubes; first and second end caps located at first and second ends of the tubes, respectively, the first end cap including a dialysis fluid inlet and a dialysis fluid outlet, the end caps and the tubes configured such that dialysis fluid can flow from the fluid inlet of the first end cap, through at least one first tube to the second end cap, and through at least one second tube back to the first end cap; a conductive wire wound around an outside of the conductive tubes; and electronics configured to supply power to the conductive wire, the wire forming a primary coil of a transformer, the tubes forming a secondary coil of the transformer.

Claims

1. A dialysis fluid heating system comprising:

a housing having a width and a length, the width shorter than the length, the housing defining a fluid inlet and a fluid outlet;

conductive baffle plates located within the housing, the plates defining a winding path for dialysis fluid flowing from the fluid inlet to the fluid outlet;

a conductive wire wound around the width of the housing to form a plurality of windings, the windings forming an axis at least substantially parallel to the length of the housing; and

electronics configured to supply power to the conductive wire, the windings forming a primary coil of a transformer, the conductive baffle plates forming a seconding coil of the transformer, the baffle plates becoming heated due to i²R losses and in turn heating the dialysis fluid flowing.

2. The dialysis fluid heating system of claim 1, wherein the baffle plates are separate from each other.

3. The dialysis fluid heating system of claim 1, wherein the baffle plates are formed from a single sheet of metal.

4. The dialysis fluid heating system of claim 1, wherein the housing is at least one of:

(i) electrically insulating and (ii) configured with electrically insulating plates that are interspersed between the baffle plates.

5. The dialysis fluid heating system of claim 1, wherein the baffle plates and the housing are configured such that the dialysis fluid is directed in a direction of the length of the housing.

6. The dialysis fluid heating system of claim 1, wherein a number of the baffle plates is optimized with a temperature to which the baffle plates are heated and with a size of the baffle plates.

7. The dialysis fluid heating system of claim 1, wherein at least one of the baffle plates is sintered or includes a non-uniform surface to increase heat transfer.

8. The dialysis fluid heating system of claim 1, wherein the baffle plates define an aperture at one end to allow fluid to flow through the plates.

9. The dialysis fluid heating system of claim 1, wherein the housing is connected to a disposable pumping cassette.

10. The dialysis fluid heating system of claim 9, wherein the disposable pumping cassette includes first and second collar reinforced tubing ports connected via first and second tubes to the fluid inlet and the fluid outlet, respectively.

11. The dialysis fluid heating system of claim 1, wherein at least one of:

(i) the baffle plates are stainless steel;

(ii) the baffle plates have a high magnetic permeability;

(iii) the conductive wire is multi-stranded;

(iv) the conductive wire is wound to form a coil extending past one or both ends of the plurality of conductive baffle plates;

(v) the conductive wire is wound to form a tight coil with at least substantially no space between windings;

(vi) the conductive wire is wound to form a coil with at least one gap between a pair windings;

(vii) a fluid mixing element is placed between the baffle plates;

(viii) the wire is at least partially surrounded by a magnetic core; and

(iv) the electronics arc configured to supply high frequency alternating current power to the conductive wire.

12. A dialysis fluid heating system comprising:

a housing having a width and a length, the width shorter than the length, the housing defining a fluid inlet and a fluid outlet;

conductive baffle plates located within the housing, the plates defining a winding path for a dialysis fluid flowing from the fluid inlet to the fluid outlet;

a conductive wire wound around the width of the housing to form a plurality of windings, the windings forming an axis at least substantially perpendicular to the length of the housing; and

electronics configured to supply power to the conductive wire, the windings forming a primary coil of a transformer, the conductive baffle plates forming a secondary coil of the transformer, the baffle plates heated due to i²R losses and in turn heat the dialysis fluid.

13. The dialysis fluid heating system of claim 12, wherein the baffle plates are formed separately from each other.

14. The dialysis fluid heating system of claim 12, wherein the baffle plates are formed from a single sheet of metal.

15. The dialysis fluid heating system of claim 12, wherein the housing is at least one of:

(i) electrically insulating and (ii) configured with electrically insulating plates that are interspersed between the baffle plates.

16. The dialysis fluid heating system of claim 12, wherein the baffle plates define an aperture at one end to allow fluid to flow through the plates.

17. The dialysis fluid heating system of claim 12, wherein the housing is connected to a disposable pumping cassette.

18. The dialysis fluid heating system of claim 17, wherein the disposable pumping cassette includes first and second collar reinforced tubing ports connected via first and second tubes to the fluid inlet and the fluid outlet, respectively.

19. The dialysis fluid heating system of claim 12, wherein at least one of:

(i) the baffle plates are stainless steel;

(ii) the baffle plates have magnetic susceptibility;

(iii) the conductive wire is multi-stranded (iv) the conductive wire is wound to form a coil extending past one or both ends of the plurality of conductive baffle plates;

(v) the conductive wire is wound to form a tight coil with at least substantially no space between windings;

(vi) the conductive wire is wound to form a coil with at least one gap between a pair windings;

(vii) a fluid mixing element is placed between the baffle plates;

(viii) the wire is at least partially surrounded by a magnetic core; and

(iv) the electronics are configured to supply high frequency alternating current power to the conductive wire.

20. A dialysis fluid heating system comprising:

a housing including an inner cylindrical wall and an outer cylindrical wall defining an annular opening between the inner and outer walls, the walls connected at a first end by an end portion of the housing;

a cap placed on a second end of the housing, the cap including a fluid inlet and a fluid outlet;

a conductive cylinder attached to the cap and extending into the annular opening a distance such that a dialysis fluid can flow from the inlet of the cap on a first side of the conductive cylinder, between a cylinder edge and the end portion of the housing, along a second side of the cylinder, and out the fluid outlet of the cap;

a conductive wire wound around the housing; and

electronics configured to supply power to the conductive wire, the wire forming a primary coil of a transformer, the conductive cylinder forming a secondary coil of the transformer.

21. The dialysis fluid heating system of claim 20, wherein at least one of:

(i) the conductive wire is wound circumferentially around the outer cylindrical wall of the housing; and

(ii) the electronics are configured to supply high frequency alternating current power to the conductive wire.

22. The dialysis fluid heating system of claim 20, wherein at least one of the inner and outer cylindrical walls of the housing includes a flow divider extending along a length of the cylindrical wall and projecting towards the conductive cylinder.

23. The dialysis fluid heating system of claim 20, wherein a portion of at least one of the inner and outer cylindrical walls of the housing is raised so as to contact a first portion of the conductive cylinder, forcing flow of the dialysis fluid toward a second portion of the cylinder.

24. The dialysis fluid heating system of claim 20, wherein the conductive cylinder has at least one characteristic selected from the group consisting of:

(i) having a surface area that is optimized with a thickness of the conductive cylinder and a temperature to which the conductive cylinder is heated;

(ii) the conductive cylinder is stainless steel;

(iii) the conductive cylinder is magnetically susceptible; and

(iv) the conductive wire is multi-stranded.

25. The dialysis fluid heating system of claim 20, wherein the housing is at least one of:

(i) connected to a disposable pumping cassette; and

(ii) electrically insulating.

26. The dialysis fluid heating system of claim 25, wherein the disposable pumping cassette includes first and second collar reinforced tubing ports connected via first and second tubes to the fluid inlet and the fluid outlet, respectively.

27. A dialysis fluid heating system comprising:

a housing including an inner cylindrical wall and an outer cylindrical wall defining an annular opening between the inner and outer walls, the walls connected at a first end by an end portion of the housing;

a fluid inlet and a fluid outlet;

a conductive cylinder made of porous metal and positioned between the inner cylindrical wall and the outer cylindrical wall such that a dialysis fluid can flow from the inlet on a first side of the conductive cylinder, through the porous metal of the cylinder, along a second side of the cylinder and out the outlet;

a conductive wire wound around the housing; and

electronics configured to supply power to the conductive wire, the wire forming a primary coil of a transformer, the conductive cylinder forming a secondary coil of the transformer.

28. A dialysis fluid heating system comprising:

a housing;

a plurality of conductive tubes connected to a first end of the housing and extending to a second end of the housing, the first end of the housing including a dialysis fluid inlet and a dialysis fluid outlet, the housing and the tubes configured such that dialysis fluid can flow from the fluid inlet, through one of an inside and outside of the tubes at an end of the tubes adjacent to the second end of the housing and back along the other of the inside and outside of the tubes to the fluid outlet;

a conductive wire wound around an outside of the housing; and

electronics configured to supply power to the conductive wire, the wire forming a primary coil of a transformer, the tubes forming a secondary coil of the transformer.

29. The dialysis fluid heating system of claim 28, wherein at least one of the first and second ends of the housing is integral with a sidewall of the housing and the other of the first and second ends of the housing includes a cap that is connected to a body.

30. The dialysis fluid heating system of claim 28, wherein the housing is configured to bend at least partially and individually around diameters of the tubes.

31. The dialysis fluid heating system of claim 28, wherein the conductive wire is at least one of:

(i) wound to form a coil having an axis that is generally parallel with an axis of the tubes;

(ii) wound to form a coil extending past one or both ends of the plurality of conductive tubes;

(iii) wound to form a tight coil with at least substantially no space between windings;

(iv) wound to form a coil with at least one gap between a pair windings; and

(v) at least partially surrounded by a magnetic core.

32. The dialysis fluid heating system of claim 28, wherein at least one of:

(i) the tubes are stainless steel;

(ii) the tubes have magnetic susceptibility;

(iii) the conductive wire is multi-stranded;

(iv) the housing is electrically insulating;

(v) a static mixer is located inside at least one of the tubes; and

(iv) the electronics are configured to supply high frequency alternating current power to the conductive wire.

33. The dialysis fluid heating system of claim 28, wherein the housing is connected to a disposable pumping cassette.

34. The dialysis fluid heating system of claim 33, wherein the disposable pumping cassette includes first and second collar reinforced tubing ports connected via first and second tubes to the fluid inlet and the fluid outlet, respectively.

35. A dialysis fluid heating system comprising:

a housing;

a plurality of conductive tubes within the housing and connected to first and second ends of the housing, the first end of the housing including a dialysis fluid inlet and a dialysis fluid outlet, the housing and the tubes configured such that dialysis fluid can flow from the fluid inlet, outside the tubes, to the fluid outlet;

a conductive wire wound around an outside of the housing; and

electronics configured to supply power to the conductive wire, the wire forming a primary coil of a transformer, the tubes forming a secondary coil of the transformer.

36. The dialysis fluid heating system of claim 35, which includes a temperature sensor positioned to measure a temperature of an inside of one of the tubes.

37. The dialysis fluid heating system of claim 35, wherein the housing and the tubes are configured and arranged such that the dialysis fluid can flow from the fluid inlet, outside the tubes along a first side of the housing, back along the outside of the tubes along a second side of the housing, to the fluid outlet.

38. The dialysis fluid heating system of claim 35, wherein the housing is at least one of:

(i) connected to a disposable pumping cassette;

(ii) electrically insulating; and

(iii) at least partially surrounded by a magnetic core.

39. The dialysis fluid heating system of claim 38, wherein the disposable pumping cassette includes first and second collar reinforced tubing ports connected via first and second tubes to the fluid inlet and the fluid outlet, respectively.

40. A dialysis fluid heating system comprising:

a plurality of conductive tubes;

first and second end caps located at first and second ends of the tubes, respectively, the first end cap including a dialysis fluid inlet and a dialysis fluid outlet, the end caps and the tubes configured such that dialysis fluid can flow from the fluid inlet of the first end cap, through at least one first tube to the second end cap, and through at least one second tube back to the first end cap;

a conductive wire wound around an outside of the conductive tubes; and

electronics configured to supply power to the conductive wire, the wire forming a primary coil of a transformer, the tubes forming a secondary coil of the transformer.

41. The dialysis fluid heating system of claim 40, wherein the conductive wire is at least one of:

(i) wound to form a coil having an axis that is generally parallel with an axis of the conductive tubes;

(ii) wound to form a coil extending past one or both ends of the plurality of conductive tubes;

(iii) wound to form a tight coil with at least substantially no space between windings;

(iv) wound to form a coil with at least one gap between a pair windings; and

(v) at least partially surrounded by a magnetic core.

42. The dialysis fluid heating system of claim 40, the first end cap further configured such that the dialysis fluid flows to the fluid outlet after flowing through the at least one second tube to the first cap.

43. The dialysis fluid heating system of claim 40, the first and second end caps further configured such that fluid flows (i) through at least one third tube from the first end cap to the second end cap after flowing through the at least one second tube, and (ii) through at least one fourth tube to the first end cap.

44. The dialysis fluid heating system of claim 43, wherein at least one of the first and second end caps defines at least one of (i) a diagonal path relative to a side of the at least one of the first and second end caps and (ii) a parallel path relative to side of the at least one of the first and second end caps, the at least one path extending within the at least one of the first and second end caps from one of the conductive tubes to another of the conductive tubes.

45. The dialysis fluid heating system of claim 40, which includes at least one of:

(i) a static mixer located inside at least one of the tubes and (ii) a temperature sensor positioned to measure a temperature of an outside of one of the conductive tubes.

46. The dialysis fluid heating system of claim 40, wherein a number of the conductive tubes is optimized with a temperature to which the conductive tubes are heated and with a size of the conductive tubes.

47. The dialysis fluid heating system of claim 40, which includes an insulating jacket placed between the conductive wire and the plurality of conductive tubes.

48. The dialysis fluid heating system of claim 47, wherein the conductive wire and the insulating jacket are part of a dialysis instrument, and the conductive tubes and end caps are part of a dialysis disposable operable with the dialysis instrument.

49. The dialysis fluid heating system of claim 40, wherein the first end cap is connected to a disposable pumping cassette.

50. The dialysis fluid heating system of claim 49, wherein the disposable pumping cassette includes first and second collar reinforced tubing ports connected via first and second tubes to the fluid inlet and the fluid outlet of the first end cap.

51. The dialysis fluid heating system of claim 40, wherein at least one of:

(i) the tubes are stainless steel;

(ii) the tubes have magnetic susceptibility;

(iii) the tubes are chamfered at at least one end;

(iv) the tubes are at least substantially round;

(v) the tubes are at least substantially square;

(vi) the tubes are formed from at least one tube having a divider wall;

(vii) the wire is multi-stranded;

(viii) the end caps are electrically insulating; and

(iv) the electronics are configured to supply high frequency alternating current power to the conductive wire.

52. A dialysis fluid heating system comprising:

a plurality of conductive tubes;

first and second end caps located at first and second ends of the tubes, the first end cap including a dialysis fluid inlet, the second end cap including a dialysis fluid outlet, the end caps and the tubes configured such that the dialysis fluid can flow from the fluid inlet of the first end cap, through at least one first tube to the second end cap, through at least one second tube back to the first end cap, and through at least one third tube back to the second end cap;

a conductive wire wound around an outside of the conductive tubes; and

electronics configured to supply power to the conductive wire, the wire forming a primary coil of a transformer, the tubes forming a secondary coil of the transformer.

53. The dialysis fluid heating system of claim 52, the first end cap further configured such that the dialysis fluid flows to the fluid outlet after flowing through the at least one third tube to the second end cap.

54. The dialysis fluid heating system of claim 52, the first and second end caps further configured such that fluid flows (i) through at least one fourth tube from the second end cap to the first end cap after flowing through the at least one third tube, and (ii) through at least one fifth tube to the second end cap.

55. The dialysis fluid heating system of claim 52, wherein at least one of:

(i) a static mixer is located inside at least one of the tubes;

(ii) the first end cap is connected to a disposable pumping cassette;

(iii) the conductive wire is wound to form a coil extending past one or both ends of the plurality of conductive tubes;

(iv) the conductive wire is wound to form a tight coil with at least substantially no space between windings;

(v) the conductive wire is wound to form a coil with at least one gap between a pair windings;

(vi) the end caps are electrically insulating;

(viii) the wire is at least partially surrounded by a magnetic core; and

(ix) the electronics are configured to supply high frequency alternating current power to the conductive wire.

56. The dialysis fluid heating system of claim 55, wherein the disposable pumping cassette includes first and second collar reinforced tubing ports connected via first and second tubes to the fluid inlet and the fluid outlet, respectively.

57. A dialysis fluid heating system comprising:

a tube;

an end cap located at a first end of the tube, the end cap including a dialysis fluid inlet and a dialysis fluid outlet;

a filler extending into the tube, the filler configured such that the dialysis fluid is urged to flow from the fluid inlet to a second end of the tube and back to the dialysis fluid outlet;

a conductive wire wound around an outside of the tube; and

electronics configured to supply power to the conductive wire, the wire forming a primary coil of a transformer, at least one of the tube and the filler being conductive and forming a secondary coil of the transformer.

58. The dialysis fluid heating system of claim 57, wherein the filler includes one of:

a strip of twisted plastic, a strip of twisted metal and a metal mesh.

59. The dialysis fluid heating system of claim 58, wherein the strip of metal is at least one of:

(i) connected to the end cap;

(ii) stainless steel;

(iii) magnetically susceptible;

(iv) roughened; and

(iv) sintered.

60. The dialysis fluid heating system of claim 57, wherein the tube is at least one of:

(i) conductive;

(ii) insulating;

(iii) integrally closed at the second end;

(iv) rounded at the second end; and

(v) closed at the second end by a second end cap.

61. The dialysis fluid heating system of claim 57, wherein the tube is conductive, and which includes an insulating jacket between the tube and the conductive wire.

62. The dialysis fluid heating system of claim 61, the wire and jacket are part of a dialysis instrument, and the tube and filler are part of a dialysis disposable operable with the dialysis instrument.

63. The dialysis fluid heating system of claim 57, wherein the end cap is at least one of:

(i) connected to a disposable dialysis pumping cassette; and

(ii) electrically insulating.

64. The dialysis fluid heating system of claim 63, wherein the disposable dialysis pumping cassette includes first and second collar reinforced tubing ports connected via first and second tubes to the dialysis fluid inlet and the dialysis fluid outlet of the end cap.

65. The dialysis fluid heating system of claim 57, wherein the conductive wire is at least one of:

(i) wound to form a coil having an axis that is generally parallel with an axis of the tube;

(ii) wound to form a coil extending past one or both ends of the plurality of tube;

(iii) wound to form a tight coil with at least substantially no space between windings;

(iv) wound to form a coil with at least one gap between a pair windings;

(v) at least partially surrounded by a magnetic core; and

(iv) supplied with high frequency alternating current power from the electronics.

66. A dialysis fluid heating system comprising:

an insulating housing including an inner ring and an outer ring, the outer ring including a dialysis fluid inlet and a dialysis fluid outlet;

first and second conductive washers connected to the inner and outer rings, the rings and washers configured such that dialysis fluid is urged to flow from the dialysis fluid inlet, around the inner ring, to the dialysis fluid outlet;

a primary coil of a transformer positioned adjacent to at least one of the first and second washers; and

electronics configured to supply power to the primary coil, first and second plates forming a secondary coil of the transformer.

67. The dialysis fluid heating system of claim 66, which includes a plurality of baffles connecting the inner and outer rings and configured to disrupt flow of the dialysis fluid while flowing around the inner ring.

68. The dialysis fluid heating system of claim 66, wherein the dialysis fluid inlet and outlet each include a collar reinforced tubing port.

69. The dialysis fluid heating system of claim 66, wherein an internal volume defined by the rings and plates is larger than a volume of the dialysis fluid inlet.

70. The dialysis fluid heating system of claim 66, wherein at least one of:

(i) the primary coil of the transformer includes a cylinder extending into the inner ring;

(ii) the primary coil is at least partially surrounded by a magnetic core; and

(iii) the primary coil is supplied with high frequency alternating current power from the electronics.

71. The dialysis fluid heating system of claim 66, wherein at least one of:

(i) the primary coil of the transformer includes a wire wound around the first and second washers;

(ii) the primary coil is at least partially surrounded by a magnetic core; and

(iii) the primary coil is supplied with high frequency alternating current power from the electronics.

72. The dialysis fluid heating system of claim 66, the primary coil being part of a dialysis instrument, the rings and washers part of a dialysis disposable operable with the dialysis instrument.

73. The dialysis fluid heating system of claim 66, wherein the outer ring is connected to a disposable dialysis pumping cassette.

74. The dialysis fluid heating system of claim 73, wherein the disposable dialysis pumping cassette includes first and second collar reinforced tubing ports connected via first and second tubes to the dialysis fluid inlet and the dialysis fluid outlet of the outer ring.

75. A dialysis fluid heating system comprising:

a primary transformer coil;

a serpentine dialysis fluid flow path defined at least in part by a plurality of twisted metal strips, the strips operable to make flow of dialysis fluid more turbulent; and

electronics configured to supply power to the primary transformer coil, the strips forming a secondary transformer coil.

76. The dialysis fluid heating system of claim 75, wherein the fluid flow path is placed in an electrically insulating housing.

77. The dialysis fluid heating system of claim 75, wherein the strips are at least one of:

(i) stainless steel;

(ii) roughened;

(iii) sintered;

(iv) magnetically susceptible; and

(v) connected at one end to a housing.

78. The dialysis fluid heating system of claim 75, wherein a first layer is positioned with respect to a second layer to enclose the dialysis fluid flow path.

79. A dialysis fluid heating system comprising:

a housing including a first leg, the first leg separated into multiple zones, a second leg, the second leg separated into multiple zones, the first and second legs bridged together at a first end of the housing, the first and second legs individually enclosed at a second end of the housing;

a fluid inlet and a fluid outlet secured to the first end of the housing;

conductive plates placed into the multiple zones of the first and second legs;

a primary coil of a transformer placed between the first and second legs; and

electronics configured to supply power to the primary coil, the conductive plates forming a secondary coil of the transformer.

80. The dialysis fluid heating system of claim 79, the fluid inlet positioned to input fluid into one of the zones of the first leg, the fluid outlet positioned to receive fluid from one of the zones of the second leg.

81. The dialysis fluid heating system of claim 79, the first and second legs end including baffles separating the zones, the baffles staggered so as to direct the dialysis fluid in a serpentine manner across the zones of the first and second legs.

82. The dialysis fluid heating system of claim 79, wherein at least one of:

(i) the primary coil is a pancake coil;

(ii) the primary coil is at least partially surrounded by a magnetic core; and

(iii) the primary coil is supplied with high frequency alternating current power from the electronics.

83. A dialysis fluid system comprising:

a dialysis instrument including at least one pump actuator and at least one valve actuator;

a disposable cassette including at least one pump chamber and at least one valve chamber operable with the pump and valve actuators, respectively, a flow path leading from one of the pump or valve chambers to a fluid heating pathway, the fluid heating pathway defined at least in part by a plurality of thermally conductive baffles; and

an energy source powered via the instrument and operably coupled to the conductive baffles and configured to cause the baffles to heat and in turn heat dialysis fluid flowing through the heating pathway.

84. The dialysis fluid heating system of claim 83, wherein the baffles are at least one of:

(i) separate from each other;

(ii) formed from a single sheet of metal and (iii) positioned so as to accommodate insulating plates that are interspersed between the baffles;

(iv) formed with a non-uniform surface to increase heat transfer; and

(v) made of a sintered metal.

85. The dialysis fluid heating system of claim 83, wherein the energy source includes one of:

(i) an electrical power source connected physically to the baffles; and

(ii) at least one primary coil of a transformer.

86. The dialysis fluid heating system of claim 85, wherein the primary coil is at least one of:

(i) positioned on one or two sides of the disposable cassette;

(ii) a helically wound wire;

(iii) a multi-stranded wire;

(iv) a pancake coil; and

(v) at least partially surrounded by a magnetic core.

87. The dialysis fluid heating system of claim 83, wherein the disposable cassette includes at least one heat strip extending from the cassette and connected thermally to the baffles, the electrical power source connected to the at least one heat strip.

88. The dialysis fluid heating system of claim 83, wherein the thermally conductive baffles are at least one of:

(i) metallic layers applied to insulating baffles;

(ii) conductive spheres placed between insulating baffles;

(iii) made of powdered metal;

(iv) made of a metal mesh; and

(v) made of an insulating material filled with conductive particles.

89. A dialysis fluid system comprising:

a dialysis instrument including at least one pump actuator and at least one valve actuator;

a disposable cassette including at least one pump chamber and at least one valve chamber operable with the pump and valve actuators, respectively, a flow path leading from one of the pump or valve chambers to a fluid heating pathway, the fluid heating pathway defined at least in part by a plurality of baffles; and

a heating strip positioned to heat dialysis fluid as it flows along the baffles.

90. The dialysis fluid heating system of claim 89, wherein the heating strip extends outside of the disposable cassette.