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1. (WO1997018001) HEATED RESPIRATORY CONDUIT
Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters

CLAIMS:

1. A heated gases transportation pathway for use in a ventilation system adapted to supply a gases flow within said gases transportation pathway:
a conduit ofa predetermined length having an internal surface and a longitudinal axis,
a heating means ofa predetermined length adapted to heat said gases flow and/or said conduit wherein said heating means is positioned within said conduit means and in said gases flow wherein said heating means are elastically flexible and are formed into a predetermined shape which circumscribes a volume which is a portion ofthe volume of said conduit.

2. A heated gases transportation pathway as claimed in claim 1 wherein the volume which said heating means circumscribes is substantially circular in cross-section having a longitudinal axis substantially aligned with the axis of said conduit such that impedance to the flow of said gases is minimised while maintaining a high heat transfer to said gases flow.

3. A heated gases transportation pathway as claimed in claim 1 or claim 2 wherein said heating means comprises a single length of electrically insulated resistance wire adapted for connection to a power supply means, wherein said resistance wire is wound into a helix which circumscribes said volume.

4. A heated gases transportation pathway as claimed in claim 3 wherein said resistance wire is wound into a double helix in order that both ends of said resistance wire may be provided at one end of said conduit for connection to said power supply means.

5. A heated gases transportation pathway as claimed in claim 1 or claim 2 wherein said heating means has an electrically insulating coating which assists said heating means in retaining shape wherein when wound into a new shape and heated above a predetermined temperature, said heating means will, upon cooling, tend to elastically retain said new shape.

6. A heated gases transportation pathway as claimed in claim 3 or claim 4 wherein a part of said heating means is adjustably fixed to said conduit in order to adjustably fix the pitch and/or diameter of said helically wound wire, the pitch and/or diameter requiring adjustment in order to minimise condensation occurring between adjacent turns of said helically wound wire.

7. A heated gases transportation pathway as claimed in claim 3 or claim 4 wherein the pitch and/or diameter of said helix varies along said heating means.

8. A heated gases transportation pathway as claimed in claim 7 wherein said ventilation system includes an inspiratory conduit means adapted to supply said gases to a patient from a humidifier end of said inspiratory conduit means to a patient end of said inspiratory conduit means, wherein the pitch of said helix is tighter at said humidifier end.

9. A heated gases transportation pathway as claimed in claim 7 wherein said ventilation system includes an expiratory conduit means adapted to channel said gases from a patient at a patient end of said expiratory conduit means to a discharge end of said expiratory conduit means, wherein the pitch of said helix is tighter at said patient end.

10. A heated gases transportation pathway as claimed in claim 7 wherein the pitch of said helix varies between about 1 to about 20 turns per 50 mm of conduit.

11. A heated gases transportation pathway as claimed in claim 3 or claim 4 wherein an inner sheath is inserted within and co-axial with said conduit, the ends of said inner sheath sealed to said conduit such that an insulating layer of trapped gases is formed between said inner sheath and said conduit.

12. A heated gases transportation pathway as claimed in claim 3 or claim 4 wherein said conduit is inserted into an outer sheath and the ends of said outer sheath is sealed to said conduit such that an insulating space of trapped gases are formed between said outer sheath and said conduit.

13. A heated gases transportation pathway as claimed in claim 4 wherein said resistance wire has two sections, a first double helically wound section and a second simple loop section, said double helically wound section including the two ends of said resistance wire and said simple loop section being furthest from the two ends of said wire.

14. A heated gases transportation pathway as claimed in claim 3 or claim 4 wherein the pitch of said helically wound resistance wire is between about 1 to about 20 turns per

50mm of conduit.

15. A heated gases transportation pathway as claimed in claim 3 or claim 4 wherein the diameter of said helically wound resistance wire is between about 8 mm and about 20 mm.

16. A heated gases transportation pathway for use in a ventilation system which creates a gases flow comprising:
a conduit adapted to channel said gases flow,
a heating means adapted to, upon energisation, supply heat to said gases flow within said conduit, wherein said heating means is provided in said gases flow within said conduit and is preformed such that said gases flow is forced to repeatedly cross said heating means substantially along the full length of said heating means.

17. A heated gases transportation pathway as claimed in claim 16 wherein said heating means comprises a single length of insulated resistance wire wherein said wire is wound into a helix and the diameter of said helix is less than the inner diameter of said conduit.

18. A heated gases transportation pathway as claimed in claim 16 wherein said heating means comprises a single length of insulated resistance wire wherein said wire is wound into a double helix with both ends of the wire provided at one end of said conduit.

19. A heated gases transportation pathway as claimed in claim 16 or claim 17 wherein said insulated resistance wire extends substantially between both ends of said conduit with a return cuπent path supplied by a low resistance return wire connected to one end of said insulated resistance wire which also extends substantially between both ends of said conduit.

20. A heated gases transportation pathway as claimed in claim 17 or claim 18 wherein said insulated resistance wire is insulated with a layer of thermoplastic so that said wire may be wound in said helix, heated and then cooled to cause said wire to tend to elastically retain said helical shape.

21. A heated gases transportation pathway as claimed in claim 16 or claim 17 wherein said conduit comprises a corrugated tube, an inner sheath co-axial with said conduit is provided between the heating means and the inner surface of said conduit forming a series of insulating spaces between the corrugations of said conduit and said inner sheath.

22. A heated gases transportation pathway as claimed in claim 16 or claim 17 wherein said conduit comprises a corrugated tube, an outer sheath is provided external to and coaxial with said conduit in order to form an outer insulating space around said conduit.

23. A heated gases transportation pathway as claimed in claim 22 wherein said sheath is a substantially tight fit about said conduit such that said outer insulating space comprises a series of insulating spaces between said corrugations of said conduit and said outer sheath.

24. A heated gases transportation pathway as claimed in claim 17 or claim 18 wherein the pitch and/or diameter of said helically wound insulated resistance wire is adjustable by adjustably fixing a part of said heater wire to said conduit such that adjustment of said pitch and/or diameter may be made by adjusting the position of fixing in order that condensation may be substantially eliminated from the spaces between adjacent turns of said wire on the inner conduit wall.

25. A heated gases transportation pathway as claimed in claim 17 or claim 18 wherein the pitch of said helically wound insulated resistance wire is between about 1 to about 20 turns per 50mm of conduit.

26. A heated gases transportation pathway as claimed in claim 17 or claim 18 wherein the diameter of said helically wound insulated resistance wire is between about 8 and about 20mm.

27. A heated gases transportation pathway as claimed in claim 17 or claim 18 wherein the pitch of said helix varies along said heating means.

28. A heated gases transportation pathway as claimed in claim 27 wherein said ventilation system includes an inspiratory conduit means adapted to supply said gases to a patient from a humidifier end of said inspiratory conduit means to a patient end of said inspiratory conduit means, wherein the pitch of said helix is tighter at said humidifier end.

29. A heated gases transportation pathway as claimed in claim 27 wherein said ventilation system includes an expiratory conduit means adapted to channel said gases from a patient at a patient end of said expiratory conduit means to a discharge end of said expiratory conduit means, wherein the pitch of said helix is tighter at said patient end.

30. A heated gases transportation pathway as claimed in claim 27 wherein the pitch of said helix varies between about 1 to about 20 turns per 50mm of conduit.

31. A method of producing a heated gases transportation pathway for use in a ventilation system comprising the steps of:
i) forming a conduit through which gases may be channelled,
ii) winding a predetermined length of insulated resistance wire into a helix ofa diameter less than the inside diameter of said conduit, and
iii) inserting the thus formed helically wound resistance wire into said conduit.

32. A method of producing a heated gases transportation pathway as claimed in claim 31 wherein said heater wire is wound in a double helix with both ends of said wire provided at one end of said conduit.

33. A method of producing a heated gases transportation pathway as claimed in claim 31 or claim 32 wherein said insulated resistance wire is insulated with a thermoplastic coating and said method includes the steps of heating the helically wound resistance wire to a predetermined temperature at which said insulation is softened and then cooling said resistance wire so that the cooled resistance wire will tend to elastically retain its helically wound shape.

34. A method of producing a heated gases transportation pathway as claimed in claim 33 wherein said step of heating is carried out by connecting the ends of the helically wound heater wire to a source of voltage and causing a cuπent to flow through said resistance wire of a sufficient magnitude for a predetermined time to raise the temperature of said insulating coating above said predetermined temperature.

35. A method of producing a heated gases transportation pathway as claimed in claim 33 wherein said step of heating is carried out by placing the helically wound heater wire in a heating means until said insulating coating has reached said predetermined temperature for a predetermined time.

36. A method of producing a heated gases transportation pathway as claimed in claim 31 or claim 32 wherein said step of forming said conduit includes the steps of corrugating the inner and outer surfaces of said conduit at substantially regularly spaced intervals.

37. A method of producing a heated gases transportation pathway as claimed in claim 31 or claim 32 wherein said step of winding said resistance wire includes the step of ensuring that the diameter of said helically wound resistance wire is between about 8mm and about 20mm.

38. A method of producing a heated gases transportation pathway as claimed in claim 31 or claim 32 wherein said step of winding said resistance wire includes ensuring that the pitch of said resistance wire is between about 1 and about 20 turns per 50mm of conduit.

39. A method of producing a heated gases transportation pathway as claimed in claim 31 or claim 32 wherein said step of winding said resistance wire includes the step of passing the wire around a substantially cylindrical former having an outer diameter less than the inner diameter of said conduit.

40. A method of producing a heated gases transportation pathway as claimed in claim 31 or claim 32 wherein said method also includes the step of inserting an inner sheath, within and co-axial with said conduit, prior to said step of inserting said helically wound resistance wire into said conduit and sealing the ends of said sheath to said conduit such that an insulating layer of trapped gases are formed between said inner sheath and said conduit.

41. A method of producing a heated gases transportation pathway as claimed in claim 31 or claim 32 wherein said method also includes the step of inserting said conduit into an outer sheath subsequent to said step of inserting said helically wound resistance wire into said conduit and sealing the ends of said outer sheath to said conduit such that an insulating space of trapped gases are formed between said outer sheath and said conduit.

42. A method of producing a heated gases transportation pathway as claimed in claim 31 wherein said step of winding includes the step of connecting a low resistance return wire to one end of said helically wound wire, the two remaining ends ofthe heater wire and low resistance wire combination being provided at one common end of said conduit.

43. A method of producing a heated gases transportation pathway as claimed in claim 31 wherein said step of winding is carried out on a substantially cylindrical former by spinning said former while winding a first layer of wire upon said former in a first direction along said former and then reversing direction along said former and forming a second layer on top of said first layer such that the wound wire will have a constant pitch when stretched.

44. A method of producing a heated gases transportation pathway as claimed in claim 31 wherein the step of winding is carried out on a substantially frusto-conical or tapered former by spinning said former while winding a first layer of wire upon said former in a first direction along said former and then reversing direction along said former and forming a second layer on top of said first layer such that the wound wire will have a variable pitch and/or adapter when stretched.

45. A method of producing a heated gases transportation pathway as claimed in claim 44 wherein the pitch of said wound wire varies between about 1 and about 20 turns per 50 mm of conduit.

46. A method of producing a heated gases transportation pathway as claimed in claim 44 wherein said ventilation system includes an inspiratory conduit means adapted to supply said gases to a patient from a humidifier end of said inspiratory conduit means to a patient end of said inspiratory conduit means, wherein said step of inserting the helically wound resistance wire into said conduit includes the step of aπanging that the pitch and/or diameter of said helically wound wire is tightest at said humidifier end of said inspiratory conduit means.

47. A method of producing a heated gases transportation pathway as claimed in claim 44 wherein said ventilation system includes an expiratory conduit means adapted to channel said gases from a patient at a patient end of said expiratory conduit means to a discharge end of said expiratory conduit means, wherein said step of inserting the helically wound resistance wire into said conduit includes the step of aπanging that the pitch and/or diameter of said helically wound wire is tightest at said patient end of said expiratory conduit means.

48. A method of producing a heated gases transportation pathway substantially as herein described with reference to and as illustrated by the accompanying drawings.

49. A method of producing a heated gases transportation pathway substantially as herein described with reference to and as illustrated by the accompanying drawings.

50. A humidification system substantially as herein described with reference to and as illustrated by the accompanying drawings.

51. A heater wire substantially as herein described with reference to and as illustrated by Figures 1 , 2, 3, 4, 6, 7, 8, 9 and 10 ofthe accompanying drawings.

52. A heater wire substantially as herein described with reference to and as illustrated by Figure 13 ofthe accompanying drawings.

53. A heater wire substantially as herein described with reference to and as illustrated by Figure 15 ofthe accompanying drawings.